WO1981002772A1 - Fluidized bed volume reduction of diverse radwastes - Google Patents

Fluidized bed volume reduction of diverse radwastes Download PDF

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Publication number
WO1981002772A1
WO1981002772A1 PCT/US1981/000395 US8100395W WO8102772A1 WO 1981002772 A1 WO1981002772 A1 WO 1981002772A1 US 8100395 W US8100395 W US 8100395W WO 8102772 A1 WO8102772 A1 WO 8102772A1
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WO
WIPO (PCT)
Prior art keywords
waste
vessel
bed
gas
fluidized bed
Prior art date
Application number
PCT/US1981/000395
Other languages
French (fr)
Inventor
D Drown
D Waddoups
J Mcfee
J Mcconnell
L Harwood
M Gray
N Clayton
Original Assignee
Energy Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Energy Inc filed Critical Energy Inc
Priority to AU70785/81A priority Critical patent/AU7078581A/en
Publication of WO1981002772A1 publication Critical patent/WO1981002772A1/en

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Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23JREMOVAL OR TREATMENT OF COMBUSTION PRODUCTS OR COMBUSTION RESIDUES; FLUES 
    • F23J15/00Arrangements of devices for treating smoke or fumes
    • F23J15/006Layout of treatment plant
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23GCREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/30Incineration of waste; Incinerator constructions; Details, accessories or control therefor having a fluidised bed
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23GCREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/44Details; Accessories
    • F23G5/442Waste feed arrangements
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23GCREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G5/00Incineration of waste; Incinerator constructions; Details, accessories or control therefor
    • F23G5/50Control or safety arrangements
    • GPHYSICS
    • G21NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21FPROTECTION AGAINST X-RADIATION, GAMMA RADIATION, CORPUSCULAR RADIATION OR PARTICLE BOMBARDMENT; TREATING RADIOACTIVELY CONTAMINATED MATERIAL; DECONTAMINATION ARRANGEMENTS THEREFOR
    • G21F9/00Treating radioactively contaminated material; Decontamination arrangements therefor
    • G21F9/04Treating liquids
    • G21F9/06Processing
    • G21F9/14Processing by incineration; by calcination, e.g. desiccation
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23GCREMATION FURNACES; CONSUMING WASTE PRODUCTS BY COMBUSTION
    • F23G2209/00Specific waste
    • F23G2209/18Radioactive materials
    • YGENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02EREDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E20/00Combustion technologies with mitigation potential
    • Y02E20/12Heat utilisation in combustion or incineration of waste

Definitions

  • the present invention relates generally to disposal of waste material and more particularly to a novel system , comprising method and apparatus , for safe and efficient fluidized bed volume reduction of various low level radioactive waste emanating from a nuclear reactor facility .
  • a major concern in disposal is the safety of transporting the treated waste to its final disposal site .
  • Fluidized beds have been separately employed for liquid calcination or combustible waste incineration in industrial plants for several years. For instance, see Richard C. Corey, Principals and Practices of Incineration, Wiley Interscience, New York, 1969, page 239. Moreover, fluidized bed calcination or radioactive wastes was broadly developed during the period of 1952 to 1959 at the Idaho National Engineering Laboratory. Use of calcination for liquid radwaste reduction was broadly employed in an engineering scale facility, the Waste Calcining Facility (WCF) , at the Idaho Chemical Processing Plant in 1963. The WCF results are summarized in a publication by one of the present applicants, T.K.
  • a batch operated fluizied bed calciner was designed and built as part of the Midwest Fuel Recovery Plant (MCRP) at Morris, Illinois for General Electric Company.
  • a batch calcination process was employed on a fully radioactive basis in the WSEP program from about 1966 to about 1970. This process was developed at Oak Ridge National Laboratory for the specific purpose of solidification of high level radioactive liquid waste but did not employ a fluidized bed process.
  • Incineration per se of solid combustible radioactive wastes has been in use as a disposal technique since 1948 when a pilot plant incinerator and off-gas clean-up system was built at Mound Laboratory. The earlier systems were adaptations of standard refuse incinerators and demonstrated that considerable volume reduction in waste handling was possible. Data taken in the early 1960 's at the General Electric Atomic Power Equipment Department in San Jose, California showed that about 99% of the radioactivity of the incinerated wastes remained in the ash. Similar data was reported from an incinerator at Pratt and Witney Aircraft where approximately 99.1 to 99.98% of the radioactivity remained in the ash. For a discussion of various incinerators for radwaste treatment, attention is directed to B.L.
  • Fluidized beds which have been previously employed solely to convert liquid waste streams including radioactive streams to solid particles, were composed of the resulting solid products from previous drying or calcining a liquid waste stream similiar to the one being treated.
  • the difficulty encountered was that the fluidized particles were simultaneously subject to growth, from deposition of new liquid waste on the surface where the water flashed off leaving a layer of resulting solids, and size reduction caused by the "self—grinding" action of the particles colliding with each or with any solid surface to which they were exposed.
  • the simultaneous growth and size reduction processes were very critical to proper operation because fluidizing properties were a function of particle size. While some particle growth could be tolerated, large particles required high fluidizing velocities which were detrimental to the operation of other system components.
  • This particle growth and size reduction phenomena was greatly influenced by the chemical characteristics and composition of the liquid waste stream being converted to the solid. For instance, if the total solids content (dissolved and undissolved) of the waste was less than a certain value (dependent upon the chemical identity of the liquid waste), it was not possible to grow fluidized bed particles. This is due to the size reduction (attrition) rate being greater than the size increase (growth) rate because of the small amount of solid-building material present in the liquid waste stream.
  • the present invention comprises a system, including method and apparatus, for fluidized bed volume reduction of the low level radioactive wastes emanating from a nuclear facility, such as a light water nuclear power reactor.
  • a single fluidized bed vessel is used in any one of three modes of volume reduction upon command, i.e. for (a) incineration of solid combustible radwaste, (b) incineration of ion exchange resins and filter sludges (these two materials are considered the same throughout this document) and (c) calcination of liquid waste.
  • a novel integrated waste influent system injects only one of the mentioned radwastes at any one point in time, while a single improved off-gas system processes and cleans off-gas derived from the fluidized bed treatment of each of the mentioned radwastes.
  • the following features are or may be provided: (a) removal of iodine from the off-gas at an adsorber site before the off-gas is released to the atmosphere; (b) recirculation and/or storage of bed materials respectively used during each mode of operation; (c) abrasive scouring of any crust formation on the bed particles; (d) an off-gas venturi scrubber, providing a variable pressure drop; (e) bed material processing for clinker and tramp removal; (f) additive to increase the melting point of the residue that form during the incineration of ion exchange resins and filter sludges; (g) novel preheating auxiliary heating of the bed; (h) an air cooled corrosion resistant fluidized bed vessel which dramatically increases life expectancy; (i) operation of the vessel at less than atmospheric pressure; (j) a unique automated instrumentation and remote control system to provide operator information, monitor performance characteristics, implement start up and shut down and cause the issuance of alarms (under abnormal conditions) ; (k) a scrub system for effective removal of
  • An additional important object is the provision of an improved system, including method and apparatus having a common fluidized bed vessel by which most low level radioactive wastes from a nuclear facility, including resins and sludges, solid combustibles, and liquids are incinerated or calcined at successive time intervals.
  • An additional dominant object according to the present invention is the provision of an integrated waste storage and handling system for selective displacement of the various radioactive wastes from a reactor facility at different intervals of time for volume reduction in a common fluidized bed vessel throucrh incineration and calcination.
  • Another principal obj ect is the provision for recir culation , cleaning , and storage o f bed material for each o f three modes of radwaste fluidized bed incineration and calcination .
  • An additional paramount obj ect is the provision of a radwaste volume reduction system having a single improved off-gas system by which cooled and cleaned off-gas is released to the atmosphere following processing by which solids are removed from the off-gas , independent of the particular type of radwaste from which the off-gas comingled with solids is originally derived.
  • Figures 1 , 1A , IB , 1C and 1D are diagramatic representations of the various types of waste emanating from different light water power reactors ;
  • Figure 2 is a layout showing the relationship of Figures 3-6 ;
  • Figure 3 is a cross section of a combination incinerator/- calcinator fluidized bed vessel , according to the present invention ;
  • FIG. 4 is a schematic representation of a feed system , according to the present invention.
  • FIG. 5 is a schematic representation of a bed material storage and handling system, according to the present invention.
  • Figure 6 is a schematic representation of an off-gas treatment system, according to the present invention .
  • Figure 7 is an exploded perspective of a venturi scrubbier having a variable throat ;
  • Figure 8 is an enlarged exploded cross section taken along line 8-8 of Figure 7 ;
  • Figure 9 is an enlarged cross section taken along line 9-9 of Figure 7;
  • Figure 10 is a side elevation, with parts broken away for clarity, of the assembled venturi scrubber of Figure 7;
  • FIG 11 is an enlarged side elevation, with parts broken away for clarity, of the variable throat mechanism of the venturi scrubber of Figure 7;
  • Figure 12 is an enlarged cross section of another variable throat mechanism for a venturi scrubber
  • Figure 13 is a perspective of an iodine, adsorber according to the present invention.
  • Figure 14 is an elevation of one of two screen mechanisms used within the iodine adsorber of Figure 13;
  • Figures 15A, 15B, and 16-26 are schematics of a presently preferred instrumentation and control system for use in conjunction with the apparatus of Figures 3-6;
  • Figure 27 is a symbol chart for interlock system of the presently preferred instrumentation and control.
  • Figures 28—39 are schematics of a presently preferred interlock system for use in conjunction with the mentioned instrumentation and control and the apparatus.
  • the present invention can be more fully understood by reading the following description in conjunction with the Figures which illustrate preferred apparatus according to the present invention. Also, the system, including apparatus and method, will be described in terms of treating diverse low level radioactive waste materials (radwastes) emanating from a single nuclear reactor. Although it is understood that multiple reactor stations can be serviced if capacities permit. When desired , any of the radwastes can be pretreated prior to introduction into the feed system . For instance , relatively large non-combustible solids such as tools , piping, and the like must be removed by conventional methods .
  • radwastes radioactive waste materials
  • the overall system generally designated 28 , illustrated in Figures 2-6 broadly comprises (a) a novel single stage/multiple incineration and calcination fluidized bed vessel , generally designated 30 ( Figure 3 ) , (b) an integrated diverse waste feed system, generally designated 32 ( Figure 4) , which receives various radwastes from nuclear reactor plant systems , generally designated 34 , independently stores and to some extent processes the radwastes and selectively delivers any one of the radwastes only to the vessel 30 for a desired interval of time , (c) bed storage and handling systems , generally designated 36 and 38 , respectively ( Figures 3 and 5) , and (d) an off-gas treatment system , generally designated 40 ( Figure 6) .
  • the overall system provides , for the first time , one apparatus whereby the volume of the various radwastes emanating from a nuclear reactor plant is reliably , safely , and efficiently reduced via a single stage fluidized bed reactor using , at separate times , two separate modes of incineration (one for solid combustible radwaste and one for resin and sludge radwaste) , and , at still other times , one mode of calcination (for liquid wastes on the order of 1 to 25% dissolved solid content by weight) .
  • the volume reduction, for example , for sludge is on the order of 5 to 1 and for solid combustible waste is on the order of 80 to 1. Only concentrated and anhydrous solids derived from incineration and calcination and a clean off-gas egress from the overall system. Iodine is removed from the off-gas .
  • Resin radwaste may be spent ion exchange resin beads or powdered resins .
  • Solid dry combustible radwaste may be rags , anti-contamination clothing , paper , wood , mops , lubricating oils , cleaning swipes , plastic gloves , and other dry laboratory waste . This type of waste normally has a much lower specific radioactivity than wet waste .
  • Sludge is derived from reactor liquid waste system filters . Liquid wastes result from reactor water treatment processes , equipment drains and miscellaneous clean-up systems .
  • Figure 1 identifies the various non-gaseous non-fuel wastes emanating from 1000 Mw(e) light water reactors.
  • the types of wastes shown in Figure 1 are generally typical of all commercial power reactors.
  • no single process vessel radwaste system was proposed or provided for incineration and calcination of all of the indicated wastes.
  • the system can be configured to process all of these wastes in a single vessel.
  • the volume reduction system be sized so that by continuously operating no more than 75% of the time all of the amenable radwaste emanating from a single reactor facility will be thoroughly incinerated or calcined in the fashion herein described.
  • the capacity may be varied. By knowing the magnitude of gross radwaste and the quantity of each type emanating from the mentioned reactor facility and the rates at which the in cinerator/calciner is able to selectively dispose of the wastes, the waste—handling system and the fluidized bed incinerator/calciner and the off-gas treatment system may be appropriately sized. Naturally, the greater the capacity, the less operating time required, exclusive of the time required to start the system up and shut it down (assuming less than continuous year around operation).
  • Benefits of the present invention include cost savings associated with: (a) construction of only one waste incineration/calcination facility as opposed to several, (b) fewer waste shipping containers, (c) transportation of less waste to a disposal area, (d) handling of less waste and (e) less waste placed at the disposal site. Increased safety in processing, handling, transporting, and disposing of the various radwastes and reduction in radiation exposure are also attained. All applicable governmental regulations are met or exceeded.
  • the incinerator/calciner 30 comprises an elongated hollow interior 50, defined by an interior metal shell 52.
  • the metallic enclosure or shell 52 comprises a right circular metal cylinder 54, a top 56 integral with and completely enclosing the top of the right circular cylinder 54 and a cone shaped bottom 58 terminating in a central axially disposed downwardly—directed bed material, clinker, and tramp removal opening 60.
  • the opening 60 is defined by a relatively short vertical chute 62.
  • the shell 52 defines a vapor space 64 disposed above a fluidized bed 66, which bed is contained in the lower portion of the interior shell 52.
  • the vertical wall 54 (a right circular cylinder) of the shell 52 is interrupted by an off-gas port 70 and an overfire air introductory port 72 for vapor space combustion.
  • a bed material introductory port 76 accommodates injection of bed material directly into the bed 66 (but which could be placed above the bed for gravity discharge onto the top of the bed).
  • Waste introduction ports 78/80 and 82 also exist in the cylinder 54. While only one port 82 is illustrated, it is to be appreciated that, as hereinafter more fully explained existence and use of several such ports are preferred.
  • the tapered vessel bottom 58 is interrupted by a side port 86 (by which fluidizing air is introduced into the bed 66).
  • the incinerator/calcinator vessel 30 substantially concentrically from the interior radially outwardly comprises seriatim, a cooling space 90, an intermediate metallic shell 92, a layer of relatively low temperature insulation 94 and an outside metal covering shroud or sheath 96.
  • a cooling space 90 substantially concentrically from the interior radially outwardly comprises seriatim, a cooling space 90, an intermediate metallic shell 92, a layer of relatively low temperature insulation 94 and an outside metal covering shroud or sheath 96.
  • Each of the mentioned components accommodates various piping, plumbing and conduits, which service the vessel through the previously mentioned ports in the inner shell 52.
  • a fluidized air duct 122 passes through the port 86 and attaches to fluidizing manifold 116 which contains fluidizing orifices 118.
  • the plenum 116 comprises part of an air delivery system, generally designated 120, which is serviced by a suitable combustion chamber or heater 124 and an air blower 126.
  • Fuel is conducted into the combustion chamber 124 through opening 74 by a fuel pump 154 from a fuel tank 150 through pipe 152.
  • Fuel oil, kerosene or the like contained within tank 150 is available along conduit 152 to variable speed fuel pump 154 and conduit 104 for injection into the combustion chamber 124 during, for example, calcination.
  • the intermediate metal layer 92 merges into a central upwardly-directed cooling air effluent conduit 130 which is axially aligned with the vessel 30.
  • Air from blower 131 (or any other suitable source) is caused to be displaced along conduit 133 and along air space 90 to service the vessel cooling needs.
  • Flow is controlled by valves 132 and 135. This heated air is then exhausted through conduit 134 and through valve 132.
  • An auxiliary blower may be used in conjunction with the conduit 134 to force exhaust cooling air out the stack.
  • air from source 126 may be caused to pass along conduit 102 (when valve 137 is open) for enhancing combustion of volatile matter in vapor space 64 of the vessel 30, which combustion occurs spontaneously, or to increase volume through off-gas duct 100.
  • Valve 137 is closed when combustion in vapor space 64 is not desired or when no increase in volume through duct 100 is desired.
  • Halide (chloride) intergranular corrosion is minimized .
  • Adequate high temperature corrosion resistance overall is provided up to 1400 °F , it being presently preferred to size the air cooling fan 131 and the related air passages and valves so as to limit the temperature of the interior shell 52 to a maximum temperature of 650 ° C during vessel operation .
  • the fluidized bed operates within the range of about 800 °C to 1200 ° C and curing calcination , within the range of about 200 °C to 550 °C .
  • hot off-gas is passed from the vessel 30 at a temperature only slightly below that of the bed temperature .
  • the pressures in the incinerator/calciner 30 , in the waste feed system , and in the off-gas clean-up system are maintained below ambient pressure in all operating modes .
  • pressure ranges from 4—6% psi below ambient at the inlet to the off-gas blower to just under atmospheric pressure in the fluizied bed .
  • Three different vessel operating modes are utilized to process the range of radwastes from a given reactor , i . e . liquid waste calcination , solid dry combustible waste incineration, and ion exchange resin and filter sludge incineration .
  • the incineration modes are separated one from the other .
  • Mode selection instrumentation and control is provided so that only one operating mode can occur at any one interval of time .
  • Each mode of operation is accommodated by the integrated waste feed system , the bed material handling system and the off gas system.
  • all other modes are rendered inoperable . Start up in all three modes requires preheating the bed 66 to the operating temperature by use of the burner 124 and fuel from source 150 .
  • the basic process is one of combustion. Efficient combustion is achieved by provision of adequate air (oxygen) and high temperatures . Almost all of the combustible waste feed is non-radioactive organic material which is intimately mixed with trace quantities of radioactive particles . The organic molecules are broken down into non-radioactive carbon dioxide and water and allowed to pass off as harmless, gases . The bulk of the waste is thus removed , leaving the radioactive material and ash behind.
  • the bulk of the activity in many types of waste are in nuclides of the elements such as strontium, manganese , iron , cesium and cobalt which will form oxides in the hot oxidizing atmosphere of the incinerator/calciner . These oxides form solid particles which are removed in the off-gas system.
  • the efficiency of the present volume reduction process is based upon the attained complete combustion and effective separation of the solids from gases in the effluent . The separation takes place in the off-gas system and is discussed hereinafter .
  • Fluidized-bed combustion is very efficient.
  • the constant agitation of the bed particles with the small pieces or droplets of the waste feed material results in a rapid rise of the waste material temperature .
  • the fluidized air which maintains the bed in its fluid state provides an ample supply of oxygen, and combustion may be enhanced by supplying overfire air above the top of the bed.
  • the thermal inertia of the bed material itself means that the system is relatively insensitive to short term variations in the exact caloric content of the feed.
  • the rubbing action of the bed wears off the brittle oxidized surface which forms on the larger waste particles and virtually insures that the center of these particles do no remain un ⁇ xidized.
  • This bed rubbing action also wears off any liquid coatings which may form on the bed particles . These coatings form because some wastes, such as plastic, may melt before oxidizing.
  • the combustible waste feed, fluidizing air, and overfire air flow rates are automatically controlled to maintain a predetermined bed temperature.
  • the burner is used to establish the desired operating temperature within the vessel prior to introduction of the dry waste. With the initiation of waste feed the burner is turned off and the temperature is maintained by the heat released from the burning waste.
  • Adequate air for incineration of ion exchange resins and filter sludges is also achieved by automatic control of flow rates of the resin/sludge feed and the fluidizing air.
  • the temperature of the fluidized bed is automatically controlled by hot gas input from the burner 124 to assure complete combustion during resin and filter sludge incineration.
  • the dry product (ash) is elutriated out of the fluidized bed and into the off-gas system, where the dry product accumulates in a product container. Any clinkers that form and any tramp material introduced with the combustible waste pass from the vessel bed 66 through the bottom opening 60.
  • the basic process is one of evaporation or drying.
  • Heat is used to drive off water as a vapor, leaving behind an incombustible residue.
  • Spraying the liquid waste into the process vessel creates droplets which are heated rapidly by their contact with the hot bed particles. As the temperature rises the water evaporates leaving dried waste material on the individual bed particles. This dried waste material is ground off the bed particles by the agitation of the bed and is elutriated from the vessel to the off-gas system. Any clinkers pass from the vessel bed through opening 60.
  • the calcination process is continuously endothermic, and heat is supplied by the heater 124 by combustion of fuel oil obtained from tank 150.
  • the fluidized bed temperature is controlled by the fuel burner.
  • the liquid waste and fluidizing air flow rates along with burner input are automatically controlled to maintain bed tempreature. Since there is no waste combustion in the overfire area in this mode, no overfire air is required.
  • the various radwastes emanating from reactor plant 34 are delivered on a segregated basis to the waste feed system 32.
  • Figure 4 illustrates solid combustible waste being communicated from the reactor plant 34 to the waste feed system 32 along conveyor 160, with resin and sludge waste being likewise communicated via conveyor 162 and liquid waste via conveyor 161.
  • conveyors 160, 162 and 161 are illustrated as comprising tubing or conduit, any suitable form of conveyance may be used for delivering the segregated wastes mentioned to the waste feed system 32.
  • the feed system 32 to the incinerator and calciner vessel 30 (shown in Figure 3) is arranged for feeding each of the three spearate types of waste to the vessel 30 at separate times.
  • this feed system is exemplary of the myriad systems which may be employed depending upon the exact wastes being treated.
  • shredding at shredder 166 or otherwise it is desirable to reduce the size of the individual particles of waste, such as by shredding at shredder 166 or otherwise, so that they can be efficiently transported into and thoroughly incinerated in the bed 66.
  • the maximum size of the particles must be smaller than the inside diameter of the transport piping leading to the process vessel and is limited, when a pneumatic feed is employed, by the flow rate of the carrier gas.
  • the presently preferred maximum dimension of pieces emitted from shredder 166 is on the order of about 2".
  • reduction of particle size when desired can be done by way of a shredder located after storage hopper 168, where the solid combustible waste is accumulated pending delivery to vessel 30. It is preferable that shredding and. loading of combustible waste into tank 168 occur simultaneously to minimize handling and personnel exposure to radiation.
  • the storage hopper 168, shredder 166 and conveyor 160 are sealed from the atmosphere to guard against possible radiological contamination of the surrounding area.
  • the hopper is sealed from the shredder when the shredder is not in use by valve 167.
  • the combustible waste is illustrated as being conveyed seriatim to incinerator/calciner 30 through a live bottom 170 in the storage hopper 168 and along a srew conveyor 172 and a pneumatic tubular conveyor 108.
  • Pneumatic conveyor 108 is serviced by blower 174.
  • Other types of conveyance can, of course, be employed.
  • the vessel 30, which may be sized for 150 pounds per hour of combustible waste, is maintained at a pressure lower than ambient pressure and the feed is to a portion of the vessel wherein the pressure is lower than ambient pressure.
  • the screw feeder 172 may be isolated vy valve 173, disposed in conduit 108, which is used to provide a positive air-tight seal when the combustible feed system is not in use.
  • the shredder 166 and the tank 168, as well as accompanying feed conduits, are preferably constructed of carbon steel.
  • Resins and sludge are conducted through conduit 162 and isolation valve 714, introduced into tank 180 and collected therein after which valve 714 is manually closed. It may be desired to collect resin in a separate tank from the sludge.
  • typical resin and sludge feeds include cation and anion exchange resin beads, powdered resin filter precoat materials (e.g., "Powdex”) , nonresinous filter precoat materials (e.g., "Solkafloc", diatamaceous earth and the like) , along with varying amounts of water.
  • the resin and sludge are conveyed via conduit 182 through valve 184 to a mixing and dewatering tank 186.
  • valve 187 a positive displacement, metering pump such as a progressive cavity pump 188, whereafter it is injected by air from compressor 189 into the vessel 30 via conduit 110.
  • a positive displacement, metering pump such as a progressive cavity pump 188
  • the distance between tank 186, valve 187, and pump 188 must be held to an absolute minimum as must the distance from pump 188 to conduit 110.
  • the waste is mechanically agitated which helps prevent bridging, compaction, or adhesion to the tank walls.
  • the slurry desirably includes only as much water as is necessary to maintain a slurry capable of being readily pumped. Feed slurries may contain from 30% to 80% by weight of solids after dewatering in tank 186.
  • Water which is obtained from dewatering can be returned to the slurry pumping system as make—up water or can be pumped to the liquid waste storage tank 192 via conduit 194 by dewatering pump 196.
  • Screen 185 prevents resins from being drawn out of the tank 186 by the pump 196.
  • kaolin clay is desirable to combine with low melting point ashes to increase their melting point and thus prevent slagging.
  • the clay is added to tank 186 through valve 197 and conduit 199 from tank 201.
  • the resin and sludge waste is introduced into vessel 30 at a position in the bed area 66 wherein the pressure is below atmospheric.
  • the equipment for the mixing and dewatering of the resin and sludge waste is preferably constructed of stainless steel.
  • Liquid waste is introduced into liquid waste tank 192 via conduit 161 and/or the recycle conduit 194. Liquid waste is pumped from tank 192 by pump 198 across valve 199, self-cleaning strainer 201 and along conduit 112 to vessel 30. Atomizing air is introduced into the liquid waste as it is conveyed to vessel 30. Compressor 113 is schematically shown as providing the mentioned air. It is preferred that the liquid waste be introduced into the vessel 30 through one or more air atomizing nozzles 114. Nozzles 114 can be remotely cleaned mechanically or with hot water and air. The liquid waste should be at a temperature above the saturation temperature of the dissolved solid wastes at the concentration in the solution. This inhibits subsequent plugging of process piping, valves, nozzles and the like.
  • Typical liquid waste can contain about 75% to about 99% water by weight along with such soluble materials as sodium sulfate, boric acid, and the like.
  • Some specific liquid waste compositions include: (a) Boiling Water Reactor (BWR) waste from a forced recirculation evaporator which normally contains about 75% water, about 22.9% sodium sulfate, about 2% sodium chloride, and 0.1% miscellaneous ingredients, (b) Pressurized Water Reactor (PWR) waste from a forced recirculation evaporator which normally includes about 73.4% water, about 14.9% sodium sulfate, about 9.6% ammonium sulfate, about 2% sodium chloride, and about 0.1% miscellaneous ingredients, and (c) boric acid waste from a forced recirculation evaporator which contains about 87.9% water, about 12% boric acid, and the remainder miscellaneous ingredients. It is desirable that the boric acid and ammonium sulfate in the liquid waste be neutral
  • the present invention employs the same fluidized bed vessel for both calcination and incineration. While it is sometimes appropriate to use a single bed material for incineration and calcination, ordinarily separate bed materials for each mode are preferred. Switching of bed materials comprises part of the present invention.
  • Each fluidized bed material is a fluidizable, granular material which is resistant to oxidation, agglomeration, and attack by chemicals such as acids and bases at temperatures up to 1200°C.
  • the use of such an inert material is advantageous in eliminating problems existent in prior fluidized bed incinerators which required a close observation of the system to assure proper operation. This was due to the fact that the particle growth and size phenomena as discussed hereinabove had to be properly controlled. Bed materials, such as quartz, which do not possess the above properties would not be successful in the present invention.
  • bed materials which can possess all of the above properties include chrysolite , olivine , kyanite , corumdum, mullite and alumina.
  • Manufactured bed materials may consist of particles of alumina or porcelain or similar material that have been pelletized and sintered or formed and crushed to the desired size . Natural material such as orthosilicates or corundum may be used.
  • the particles may be coated with a resistant material priorto charging to the fluidized bed .
  • the coating may be applied in the fluidized bed using the heat of the process vessel itself .
  • the size of the bed particles in accordance with the present invention is not greatly affected by contacts in the bed due to the hardness of the material from which the bed particles are made and the soft friable nature of the dry calcine.
  • the system is also largely independent of the chemical composition of the waste because of the inertness of the bed . This is important in an application such as a commercial electrical generating station radwaste volume reduction system because the chemical composition of the waste could comprise a number of corrosive and otherwise active ingredients .
  • the system also provides a new bed make— up capability to compensate for bed losses through elutriation and occasional clinker formation .
  • the system remotely draws a metered quantity of material from the new bed storage tank and inj ects it into the fluidized bed during operation .
  • Bed media that has been exposed to the chemical environment of the calcination mode cannot be exposed to the high temperatures of the incineration mode without excessive clinker formation. This condition is created because the high temperature of the incineration mode exceeds the melting point of residual salts deposited on the bed media during calcination. A similar situation does not occur when converting from the incineration mode to the calcination mode.
  • the bed handling design include the capability to remove the bed used in calcination and recharge with appropriate bed material prior to start-up in the incineration mode. In some applications it may be economically justifiable to simply dispose of the calcine bed and recharge with fresh bed material. Normally, however, it will be necessary to maintain a separate bed inventory for operation in each mode and to provide the necessary handling capabilities for bed change-outs and storage.
  • bed change-out with minimum interference during the mode transition period is provided.
  • the entire bed may be removed in a relatively short time.
  • a rapid bed dumping capability is provided to withdraw a resin incinerating bed in the event of a loss of fluidizing air.
  • the bed outlet valve 141 is controlled to evacuate the bed from the vessel 30 before any type of permanent harm results. Such an event would otherwise result in a solidification of the bed within a short period of time.
  • the bed handling system is designed to accommodate radioactively contaminated bed material.
  • the handling and storage equipment is totally enclosed and operated at less than atmospheric pressure to preclude the release of airborne contamination .
  • the system is remotely operable so far as practicable .
  • screened bed material be conveyed to its appropriate storage location. Since the same bed material handling system is used to transport both incineration and calcination bed material , it is self-cleaning to preclude mixing residual bed material with that handled in a subsequent mode . The conveyor and its interfaces are totally enclosed , to preclude any release of radioactive contamination . The temperature requirements of the conveyor are considerably relaxed from that of the bed removal system due to the fact that the bed will be allowed to cool in the vessel and enroute . The temperature of the bed during transport does not exceed 300 °C .
  • FIGS. 3 and 5 illustrate the presently preferred bed material storage and handling systems 36 and 38 , respectively .
  • a fresh bed material storage tank 256 into which any desired bed material may be initially placed through the top opening 258 thereof .
  • the selected bed material in tank 256 is introduced through isolation valve 264 , effluent conduit 262 , inclined gravity conveyor 106 into the vessel 30 .
  • the valve 264 is selectively operated to meter additional fresh bed material into the vessel to maintain the desired bed depth notwithstanding loss of bed material through attrition.
  • fresh bed material remaining in tank 256 may be drained therefrom through valve 260 and out spout 266 into a suitable container . No radiation exposure will result since the fresh bed material is not radioactive . Thereafter , another bed material may be introduced into the tank 256 to service the requirements o f the ensuing incineration or calcination cycle .
  • the bed material storage system 36 comprises the previously mentioned inclined gravity conveyor 106 .
  • Separate storage tanks 242 and 244 are illustrated as being provided to receive , store and selectively issue calcination bed material and incineration bed material , respectively .
  • Each of the tanks 242 and 244 are adapted to receive recirculated bed material as hereinafter more fully described .
  • Each tank 242 and 244 is equipped with selectively operated influent and effluent isolation valves 248 and 250 , respectively .
  • Each tank 242 and 244 is intended to preferably store one complete bed and each tank is in selective communication with 'the sloped gravity conveyor 106 across the associated valve 250 and an effluent conduit 252 .
  • Reclaimed bed material is delivered to the tanks 242 and 244 , respectively , across the associated valve 248 and along an influent conduit 254 . Since the used bed hoppers 242 and 244 will store one complete bed each , no metering capabilities are required for the associated isolation/feed valves . The new bed hopper 256 , however , must be able to feed discrete amounts of bed material for make-up during operation and therefore has metering capabilities . It is presently planned to allow the recycled bed material to cool to 300 °C prior to transport for storage . The hoppers 242 and 244 are therefore designed for 300 °C .
  • the bed material handling system 38 is interposed between the bottom discharge conduit 62 of the vessel 30 and four sites , i . e . a tramp material storage tank 280 , emergency bed material drum 281 , and the recycled bed material storage tanks 242 and 244 .
  • the bed material is suspended above the fluidizing manifold 116 by the air coming out the orifices 118 . Obj ects heavier than the particles o f the bed material , such as tramp material , will fall through the manifold and accumulate in the area just below the orifices 118. From time to time conveyor 272 may be operated to remove the accumulation.
  • the bed material is thus conveyed directly over collector 276 where recyclable bed material is caused to fall by gravity through a screen area at the top of the collector with reamining tramp material and clinkers being displaced by the screw conveyor 274 along the conveyor 272 past the collector 276.
  • the screw flights change from solid to a helical wire brush to prevent damaging the screen by jamming clinkers or tramp material between the screen and the screw.
  • the wire brush helps keep the screen section clean.
  • Downstream of the screen section the screw is again in solid flights to convey clinkers and foreign material to the tramp material storage tank 280.
  • the conveyor is inclined to enhance selfcleaning.
  • the clinkers and tramp material accordingly, fall by force of gravity along chute 278 into tramp material storage tank 280.
  • Clinkers accumulated in tank 280 are selectively discharged thereform, after cooling, across valve 282 into a clinker container 284 for solidification and subsequent transportation to a burial or other suitable radwaste disposal site.
  • Reusable bed material accumulated in collector 276 is displaced to the bed material storage system 36 where it may be stored or recycled directly to the fluidized bed vessel 30 . More specifically , the bed material accumulated in collector 276 moves by force of gravity along bed material effluent conduit 288 to the bottom area of a bucket or screw elevator conveyor 292.
  • An endless belt of buckets or vertical screw conveyor 294 in a fashion, well known in the art , delivers the reclaimed bed material upward through the entire length of the elevator conveyor 292 , where the reclaimed bed material is communicated to a screw conveyor 296.
  • Screw conveyor 296 displaced the reclaimed bed material along a conveyor 298 to the appropriate one of the recycled bed material storage tanks 242 and 244 , depending upon the bed material being processed by the bed material handling system 38 .
  • This communication occurs across the associated valve 248 and along the influent conduit 254 associated with the bed material storage tank being used .
  • the remaining valve 248 remains closed.
  • the reclaimed bed material passes from the collector 276 down bed effluent conduit 288 to the bucket conveyor 292. It is moved up to the screw conveyor 296 which displaces it through valve 297 and through the conduit 299 and into the inclined gravity conveyor 106 and from thence into the bed 66.
  • the conveyor 292 may be replaced by a pneumatic conveyor powered by an air blower , if desired .
  • the fluidized bed 66 will increase in depth. In order to maintain the proper bed depth it will be necessary to remove some bed material with the bed removal system as previosuly described and store it in the appropriate storage tank 242 or 244 . This is accomplished by running the system until the bed level is satisfactory with valves 297 and 250 closed and the appropriate valve 248 open . As part of the rapid dump system the diverter valve 141 is normally positioned such that the normally removed bed material moves by gravity along conduit 273 to conveyor 272 and then through the system as previously described.
  • valve 141 In the event of an emergency, such as loss of power while combusting resins, the valve 141 is repositioned so that the bed material flows by gravity through conduit 279 into drum 281 which is sized to hold the total bed.
  • the diverter valve 141 is actuated with loss of power while in the resin combustion mode by a return spring to the emergency position. This feature is also used when disposing of a used bed that is no longer servicable for some reason. Valve 141 is de-energized and the bed is dumped into drum 281 for disposal.
  • Air is blown into the bottom of vessel 30 via blower 126, conduit 122 and plenum 116 to maintain the bed in its fluidized condition. This also supplies the oxygen necessary for combustion. Moreover, during incineration, additional overfire air is injected via conduit 102 above the bed to enhance complete combustion.
  • the volatile particles elutriated from the bed remain above the bed in the vessel for a sufficient amount of time that any necessary afterburning for efficient combustion occurs before the elutriated noncombustible particulate matter is exhausted through hot gas duct 100 into twin dry cyclones 320 of the off-gas treatment system 40 shown in Figure 6.
  • the vessel height and additional air eliminate the need for an afterburner.
  • the static bed height for processing the amounts of materials discussed hereinabove can be from about 13 to about 26 inches.
  • the heat for the calcination and for preheating the bed is provided by heater 124 using liquid hydrocarbon fuel from tank 150.
  • heater 124 using liquid hydrocarbon fuel from tank 150.
  • introduction of waste to be incinerated supplies sufficient fuel to maintain the incineration process. If not, in a given situation additional heat can be supplied from heater 124.
  • the dry cyclones 320 are for removing solid material in the gas effluent and typically remove at least 82% of the solids contained therein.
  • the gas effluent enters the cyclones at site 322 proximate the top and tangential to one side of each cyclone to achieve a circular swirling motion in a conventional manner.
  • the solids which are separated from the gas effluent settle towards the bottom of the dry cyclone 320 and are exited therefrom via conduit 324 and are directed to a storage hopper 329 .
  • This hopper can be isolated by valves 325 and 331. When full , the hopper is emptied along conduit 327 into disposable container 326.
  • the application of externally attached vibrator 333 to the outlet of hopper 329 assures efficient discharge of the collected particulate .
  • the solid particles are then solidified by conventional means for subsequent disposal such as by burial .
  • the swirling motion of the air causes a centrifugal force to act upon the solid particles so that they migrate to the wall .
  • the air velocity is lower close to the wall due to the boundary effect so that the particles slide downward along the wall to the particulate exit 328 .
  • the gas effluent exits upward from the top center of each cyclone 320 via conduit 330 and is thence directed to quench tank 332.
  • the dry cyclones 320 can be constructed of the same types of materials as the incinerator/calciner vessel 30 and cooled in a like manner . Multiple cyclones can be placed in series or parallel thus increasing particle removal efficiency .
  • Off-gas in conduit 330 is communicated to a low side site 334 of the quench tank 332.
  • the off-gas is cooled by a liquid spray of scrub solution which is introduced into the quench tank 332 via conduit 336 and spray nozzles (not shown).
  • the off-gas remains cool throughout the remainder of the off-gas clean-up system.
  • the gas flows counter, current to the water spray which causes intimate contact between the gas and liquid streams. This causes both cooling of the off-gas and wetting of most of the remaining solid particles in the off-gas.
  • the larger liquid droplets fall to the bottom of quench tank 332 and are returned to a scrub solution tank 338 via conduit 340 taking the wetted solid particles along with them. Smaller liquid droplets are swept upwardly out of the quench tank 332 with the off-gas via conduit 342.
  • the quench tank 332 and scrub solution tank 338 are made of corrosion resistant material.
  • the off-gas exits the quench tank 332 via conduit 342 and is thence directed to venturi scrubber 344.
  • Scrub solution from conduit 336 is sprayed into the off-gas at or near the throat 346 of the venturi scrubber in a conventional manner.
  • venturi scrubber 344 it is desirable to achieve saturation and entrainment of water to facilitate wetting of those particles which were not wetted in quench tank 332.
  • the off-gas leaving vessel 30 may contain a great deal of water vapor.
  • water vapor in addition to entrained water, is added.
  • the off-gas is substantially saturated with water vapor.
  • the pressure drops which in turn causes an. increase in the amount of moisture which the gas can maintain in vapor form. Accordingly, evaporation occurs.
  • the velocity decreases and the pressure increases thereby resulting in condensation of water vacor. This condensation in turn causes the existing droplets to become larger along with causing new droplets to form on the unwetted particles which serve as condensation nuclei.
  • the primary purpose of the quench tank 332 and venturi scrubber 344 is to cool the off-gas and wet as many of the solid particles as possible to facilitate removal. It is easier to remove a liquid droplet than it is to remove a much smaller solid particle. The liquid particles are removed subsequently whether the particles are composed of soluble material which have gone into solution in the droplet or the particles are composed of insoluble material which is retained as a wetted solid within the droplet. In either situation, the solid particle moves with the liquid droplet.
  • the venturi scrubber 344 must be constructed from corrosion resistant materials.
  • the off-gas containing liquid particles is removed from the venturi scrubber 344 via conduit 352 and introduced into wet cyclone 350 via conduit 352 tangentially near the bottom in the conventional manner.
  • the wet cyclone 350 functions in a manner substantially similar to dry cyclone 320, but removes liquid droplets instead of solid particles.
  • centrifugal force causes liquid to run down the side of the cyclone to a drain 354 in the bottom thereof.
  • the liquid is then removed from the cyclone via conduit 356 and communicated to scrub solution tank 338.
  • the off-gas is exhausted from the top of the cyclone 350 through conduit 358.
  • Typical operating parameters for the cyclone 350 include a temperature range of about 54 °C to about 63°C, an inlet pressure of about 11.6 psia, a pressure differential of about 1.8 inches H 2 0 and a gas flow rate of about 4.77 to about 1140 CFM.
  • the off-gas passes through an entrainment separator 359 which removes large water droplets.
  • This unit is conventional and is constructed of a wire pad rough which the off-gas must pass. The wire must be corrosion resistant.
  • Off-gas removed from the entrainment separator 359 via conduit 361 is communicated to a condenser 360 for cooling the gas effluent. Cooling liquid is introduced and removed through conduits 362 and 364.
  • the condenser can be a shell and tube type heat exchanger, if desired. In the condenser, the liquid particles grow in size to a point wherein a significant amount of the water in the off-gas is removed by gravitational or momentum effects. In a gravitational removal mechanism, the drops are so large that they fall to the bottom of the vessel.
  • the droplets are not large enough to fall out of the off-gas stream but they are large enough so that as the gas changes direction suddenly the droplets impinge upon the wall or other solid material which has caused the direction change.
  • Off-gas leaves the condenser 360 through conduit 366.
  • Typical operating parameters for the condenser 360 include a gas flow rate of about 480-1180 CFM about 0-8.4 gallons/minute of cooling liquid, inlet temperature of about 54 to 63°C, a temperature differential of about 3-23°C, inlet pressure of about 11.5 psia, and a pressure differential of about 0.5 psi.
  • the off-gas and liquid droplets exiting the condenser 360 via conduit 366 are communicated to a mist eliminator 370.
  • the mist eliminator 370 operates to remove the liquid particles by the momentum removal effect. Off-gas is passed through a filter of woven fibers which causes the gas to undergo rapid and frequent changes in direction.
  • liquid droplets are too large to turn as sharply as the gas particles, they collide with the filter fibers.
  • the liquid droplets then run down the fiber to the wall of mist eliminator 370 and from there to the bottom drain 372 and conduit 374 which returns the liquid droplets to scrub tank 338.
  • a bed of caustic impregnated carbon is located within the SO 2 adsorber tank 377 and is supported by a horizontal screen!
  • the off-gas leaves the SO 2 adsorber 377 near the bottom via conduit 381 and is directed to a heater 378 which heats the off-gas to reduce the relative humidity below 100%. This protects the HEPA filter 380 and iodine adsorber 384 from overloading with moisture condensation.
  • the off-gas is conducted from the heater 378 to the HEPA filter 380 via conduit 376 wherein any residual solid particles which were not removed in the mist eliminator 370 are trapped (after residual moisture is evaporated by the heater 378).
  • the filter comprises a medium with very small pores and the particles are removed by impingement.
  • the off -gas exits the HEPA filter 380 via conduit 382 and enters an iodine adsorber 384 which removes iodine by adsorption .
  • the radio iodine atoms are held on the surface of the material until they decay to the stable atom xenon or are removed with the material .
  • An adsorbing agent comprising silver coated silica gel beads or KI impregnated activated carbon may be used .
  • the temperature of the off-gas through the HEPA filter 380 and iodine adsorber 384 is between about 40 and about 60 °C and the flow rate is between about 540 CFM and about 1180 CFM.
  • the off -gas is directed via conduit 386 to a second HEPA filter 388 .
  • the KEPA filters 380 and 388 are commercially available and need not be disclosed in any greater detail herein .
  • the off-gas leaving the HEPA filter 388 via conduit 390 is sufficiently decontaminated that any amountsor radioactive material which may be present in the gas are well below the levels permitted by the plant operating license and accordingly can then be discharged to the atmosphere by a blower 392 and conduit 394 to the plant stack or a separate and sole use stack. .
  • the NaOH solution is introduced from tank 397 into the scrub solution tank 338 through valve 399 and conduit 396 .
  • Any pH adjusting materials such as sodium hydoxide , are added to the scrub solution tank from time to time as needed as aqueous soltuions via conduit 396 .
  • the scrub solution is removed from the scrub tank via conduit 398 and under force of pump 400 .
  • a device 402 for removing solid particles can be included in line 398 between scrub tank 338 and pump 400. Scrub liquid is then fed to a heat exchanger 404 wherein it is cooled sufficiently so that a portion of it can be used as the spray in quench tank 332 and venturi scrubber 344 via conduit 336 .
  • Some liquid purge from the scrub tank may be returned to liquid waste tank 192 via conduit 164 .
  • the tei ⁇ oerature downstream of the scrub cooler 404 is typically about 30-50 °C .
  • a typical flow rate of the scrub solution to the quench tank 332 and venturi scrubber 344 is about 16. 5 gallons/minute and that of the scrub solution recirculating to the scrub solution tank 338 is about 11 gallons/minute .
  • venturi scrubber 344 is vertically mounted and comprises three primary portions , i . e . an approach or contraction cone , generally designated 420 , a central throat assembly , generally designated 422 , and a re-entry or expansion cone , generally designated 424 .
  • the approach cone comprises a mounting flange 426 equipped with an array of apertures 428 by which the leading end of the as sembly is secured in the offgas system in the position illustrated in Figure 6 .
  • the flange 426 integrally merges by welding, for example , at site 430 with a tunnel 432 which defines a rectangular inwardly tapered rectangular passage 434 comprising part of the flow path for the off-gas in system 40 .
  • the converging passage 434 is formed by integrally welded plates 436 , 438 , 440 and 442 .
  • the tapered proj ection 432 is welded onto the leading opening 444 of the throat assembly 422 so that the interface between the cone 420 and the throat assembly 422 is air tight and smooth .
  • the throat assembly 422 comprises a generally rectangular block 446 , a similarly shaped generally retangular block 448 and opposed , substantially identical though opposite hand side blocks 450 .
  • the blocks are secured together as illustrated in Figure 7 preferably by welding .
  • the off-gas passageway 452 (which comprises influent opening 444 and effluent opening 45.4 ) is configurated as best illustrated in Figures 10 and 11. More specifically , the interior surface 456 of the top block 446 is substantially continuous as illustrated in Figures 10 and 11 (see especially Figure 11) .
  • Surface 456 merges with o ffset surface 458 across a perpendi ⁇ cular shoulder 460 , a recessed face 461 and a second shoulder 463.
  • the stepped surface 458 is flanked on each side by a relatively narrow surface 462 which merges smoothly with surface 454.
  • the distance between the two spaced exterior surfaces 462 is only slightly greater than the width of a generally planar throat adjustment plate 464. Accordingly, the throat adjustment plate 464, when in its "out" position as illustrated in Figure 11, is entirely disposed within the rectangular space between flanges 462, shoulders 460 and 463 and surfaces 458 and 461.
  • the spaced surfaces 462 each contain an aperture 466, which apertures are aligned one with the other.
  • a pivot pin 468 fits tightly through the two apertures 466 and fully spans between the spaced flanges 462 and beyond.
  • An exposed pivot pin head 470 retains the pivot pin 468 in the illustrated position at one end, while a nut 472 tightly secured to the threaded end 474 of the pivot pin 468 secures the other end of the pin in the illustrated position.
  • the pin 468 fits loosely through an eyelet 476 of the venturi throat adjustment plate 464 and secures the adjustment plate 464 in pivotable, cantilevered fashion as illustrated in Figure 11.
  • the cantilevered portion of the adjustment plate 464 comprises a linear portion 478 integral with the eyelet 476 and tangentially disposed in respect thereto together with an angularly disposed distal end extension 480.
  • the juncture 482 between the linear portion 478 and the angular portion 480 constitutes a throat-identifying region in the assembly 422.
  • a threaded bore 484 is centrally disposed in the body 446 and receives a stop bolt 486.
  • the distal end 488 of the stop bolt 486 contiguously engages the outer surface of the venturi adjustment plate portion 478 just upstream of the throat defining portion 482.
  • Lock nut 490 can be loosened an appropriate distance and stop bolt 486 can be adjusted inward to move venturi plate 464. It is presently preferred that the venturi adjustment plate 464 be adjustable through on the order of 36°. Once a desired setting of the bolt stop 486 is obtained, the lock nut 490 is again tightened to retain the selected plate orientation. During each adjustment of the orientation of the plate 464, rotation is accommodated at eye 476 about pivot pin 468, which loosely passes through the eye.
  • a transverse scrub solution passageway 500 is disposed across the entire width of the block 446.
  • the passageway 500 is threaded at each end 502.
  • One end of passage 502 is plugged with a threaded plug having wrenching surfaces for use during installation and removal.
  • the other end of passage 502 is connected to conduit 336 ( Figure 6) for delivery of scrub solution.
  • four aligned threaded ports 504 smaller than passageway 500 span between the passageway 500 and the outer surface 506 of the body 446. Accordingly, there exist four ports 512 in block 446 which align with ports 504 and penetrate to the inside surface of block 448. These ports form nozzles 512.
  • the ports 504 are plugged, preferably with threaded plugs 509 having an exposed wrench-receiving head for placement and removal purposes.
  • Scrub solution delivered in any suitable fashion to passageway 500 is caused to be slowly sprayed under moderate pressure through the nozzle openings 512 (disposed in surface 456 directly opposite threaded ports 504) into the off-gas passageway of the throat assembly 422, whereby residual particles contained within the off-gas are wetted and encapsulated within liquid droplets and removed from the off-gas by the wet cyclone.
  • the interior face of the block 448 comprises a linear surface 520 (disposed beginning at the upstream opening 444 of the off-gas passageway through the throat assembly 422), which merges with a divergently tapered face 522.
  • the divergent face 522 terminates adjacent the effluent opening of the off-gas passage in the throat assembly.
  • the site 524 (at which the surfaces 520 and 522 merge) is disposed opposite the adjustable throat site 482 of the venturi adjustment plate 464.
  • the divergently tapered surface 522 is flanked on each side by a narrow longitudinally directed surface 526, which is contained within a plane also containing the interior surface 454 of the adjacent side block 450.
  • the bottom block 448 comprises a centrally disposed vertical threaded bore 528, which receives a second elongated threaded stop bolt 530.
  • the distal end 532 of the bolt contiguously engages the outer surface of the plate portion 478 in alignment with the previously described threaded stop bolt 486. Accordingly, each reorientation of venturi adjustment throat plate 464 will require manipulation of both threaded stop bolts 486 and 530 through loosening of the lock nuts 490 and 532 (as previously described) , threaded advancement or retraction of the threaded bolt stops by tool engagement with heads 492 and 534 to place the plate 464 as desired,, following which the lock nuts 490 and 532 are again tightened.
  • a transverse scrub solution passageway exists across the full width of the block 448 in alignment with the previously described scrub solution passage 500 in the top block.
  • the block scrub solution passage 550 is identical through the inversion of the previously described passage 500 and is correspondingly numbered. Thus, scrub solution contained under pressure in passageway 550 will be sprayed slowly through the adjacent nozzle opening 512 into the off- gas axial passageway of the throat assembly.
  • the two identical though opposite hand side blocks 450 are exteriorly rectangular. Thus, when the throat assembly 422 is assembled, all of the exterior threaded port leading to the described scrub solution passageways within the four blocks may be plugged, with the exception of two so that solution under pressure sprays into the throat assembly from opposite sides.
  • the re-entry cone 424 comprises a mounting flange 560 equipped with an array of apertures 562 by which the trailing end of the assembly is secured in the position illustrated in Figure 6.
  • the flange 560 integrally merges by welding, for example, at site 564 with a tunnel 566 which defines a rectangular outwardly divergent tapered rectangular passage 568 comprising part of the flow path of the off-gas in system 40.
  • the diverging passage 568 is formed by integrally welded plates 570, 572, 574 and 576.
  • the tapered tunnel 566 is welded to the trailing opening of the throat assembly 422 so that the interface between the re-entry cone 424 and the throat assembly 422 is air tight and smooth.
  • the manually adjustable venturi scrubber embodiment of Figures 7—11 is available to vary the cross sectional area of the throat of the venturi scrubber 344 to correspondingly vary the pressure drop at the throat.
  • the existence of a fixed venturi scrubber throat has presented problems in removing substantially all radioactive particles from the off-gas.
  • This present adjustment capability allows the operator of the overall system to optimize, on a custom basis, the condensation obtained at the venturi scrubber 344 which enhances particle removal through wetting and centrifugal action (obtained in wet cyclone 350).
  • Venturi scrubber 344 ' is substantially similar to the previously described venturi scrubber 344, except modifications exist to provide for automated and remote control of the orientation of adjustment plate 464.
  • the throat assembly 422' comprises block 446', block-448' and blocks 450.
  • the scrub solution passageways and front end portions of the blocks 446', 448' and 450 of the throat assembly 422' are identical to those of throat assembly 422.
  • the block 446' is otherwise identical to block 446, except the previously described threaded bore 484 has been removed and replaced by a smooth bore 590 which is located near the effluent end of the assembly 422' and midway across the width of block 446'.
  • Block 448' is identical to the previously described block 448, except the previously described threaded bore 528 has been eliminated.
  • the blocks 450 are the same.
  • a hydraulic, pneumatic or electric actuator assembly is superimposed over and in alignment with the smooth block bore 590 and is conventionally secured to the block 446' in any suitable way, e.g. via countersunk screws (not shown) or welded.
  • the actuator 592 comprises a two-way device 594 from which a piston rod 596 extends.
  • the rod 596 termintes in a clevis 598 which is pivotally attached at pin 600 to a rotatable link 602.
  • Link 602 is in turn pivotally connected by pivot pin 604 to a second clevis 606, the base of which is welded at site 608 to the top surface of the throat adjustment plate 464 near the distal end thereof.
  • the isolation housing of actuator 592 comprises a block 610, by which the actuator 592 is mounted to the top of the throat assembly 422'.
  • the body 610 comprises a stepped central smooth bore 612, the narrow diameter portion of which comprises a groove 614 in which a sealing O—ring 616 is disposed.
  • the block or body 610 is closed by an end plate 618 held in pos ition by cap screws 620 , which thread into, the body 610 .
  • the throat cross section and configuration may be varied by appropriately advancing and retracting the piston rod 596 through controlled actuation o f actuator 594 , on a remote basis .
  • Adsorber 384 as illustrated in Figures 13 and 14 , comprise at each end a mounting flange 640 , each flange 640 having an appropriate shape and apertures 642 by which the adsorber 384 is mounted in the off- gas system in the position illustrated and earlier described in conjunction with Figure 6 .
  • Each flange 64 0 comprises an off-gas opening 644 .
  • Adjacent to each flange 640 is a generally linear air tight hollow retangular conduit portion 646 , which integrally, by welding or otherwise , merges with an adj acent hollow truncated pyramid section 648 .
  • Each truncated section 648 is fabricated of sheet metal and is air tight and capable of resisting internal and external pressure .
  • Adj acent to each truncated pyramidal section 648 is a generally rectangular hollow sheet metal section 650 , welded or otherwise integrally secured to the adjacent truncated pyramid section 648 .
  • a pressure sensing tap 652 In each rectangular section 650 is mounted a pressure sensing tap 652 , by which the pressure differential across the iodine adsorber 384 is determined on a continuing basis .
  • Each section 650 also includes a removable inspection and access plate 654 , which, when in the assembled position and tightened , is air tight .
  • an adsorber section 656 Interposed snugly by welding or other means between the two sections 650 is an adsorber section 656 .
  • the adsorber section 656 is serviced by an inlet conduit 658 through which the adsorber bed material is introduced into the adsorber section 656 when the valve 662 is ooened and flows by gravity through the conduit 658 into a central hollow portion within the adsorber section 656.
  • Chamber 660 is a reservoir which insures that adsorber 656 remains full during operation.
  • spent adsorber bed material is discharged under force of gravity through conduit 664 when valve 666 is opened.
  • adsorber section 656 is illustrated in Figure .13 as being constructed and located so as to present surfaces aligned with the surfaces of the section 650, that flanges or other suitable mounting structure could be used so that the adsorber section could be independently inserted and removed from its assembled position in the iodine adsorber 384.
  • the interior of the adsorber 656 includes fore and aft screen assemblies 670 with a hollow space therebetween.
  • the screen assemblies 670 are intended to be spaced one from the other a predetermined distance to provide the mentioned space to thereby accommodate insertion of the adsorber bed material in the previously mentioned fashion therebetween.
  • Each screen assembly 670 (as best illustrated in Figure 14) comprises a rectangular peripheral frame 672 secured to the exterior metal shell 674 of the adsorber section 656 by welding.
  • the frame 672 has mounted thereto along the entire interior surface in an air tight fashion an endless rectangular rod 676, the corners of which are mitred.
  • a plurality of spaced rods 678 extend between parallel portions of the rod frame 676 in the perpendicular fashion illustrated.
  • the rods 678 thus form openings 680 therebetween.
  • the openings 680 are illustrated in Figure 14 as being of substantially equal size one in respect to the other.
  • the crossing rods 678 are welded or otherwise secured to each other at the sites 682 where an overlap occurs.
  • the ends of the crossing rods 678 are also secured as by welding or the like to the rod frame member 676.
  • the network of rods 676 and 678 form a strong frame against which a rectangular screen , having substantially the same peripheral dimensions as the peripheral rod 676 , is superimposed in such a fashion that the iodine adsorber beads are retained and off-gas flow is required to pass through the screen 684 without short circuiting around the edges o f the frame .
  • the adsorber bed material is introduced into the adsorber section 656 between the spaced screen 684 with off-gas air being caused, to come into intimate contact with the bed material as the off—gas is displaced through the iodine adsorber 384 .
  • iodine in the off-gas will be substantially entirely adsorbed if the media or bed material is silica gel coated with silver or activated carbon impregnated with potas sium iodide and an amine .
  • the bed material in the adsorber section 556 is depleted , it may be removed as previously described and replaced by an additional supply also introduced as described .
  • the bed material replacement can be accomplished remotely by use of remote control, valves and appropriate piping to and from the adsorber bed .
  • the instrumentation and control system provides input for control over the process , as well as informing of off- normal conditions and detects conditions that may result in excessive radiation levels exiting the off-gas system.
  • the overall system 28 shown in Figures 2- 6 is equipped with instruments designed to sense and activate alarms upon the occurrence of a wide variety of off-normal operational conditions .
  • a part of the instrumentation and control are annunicators which provide identification of the causes o f any alarm. Corrective action is taken either automatically or manually , depending on the potential seriousness of the abnormal occurrence .
  • the system 28 also monitors the off-gas system to insure that releases to the atmosphere are well within prescribed limits .
  • the instrumentation and control system provides the operator with information for process control to maintain the system parameter's within safe and efficient limits and also monitors the performance characteristics of certain components . Monitoring the performance of these components allows the operator to anticipate many problems before a system shutdown becomes necessary . For example , the scrub liquid strainer pressure differential is recorded. The operator is able to observe the effects of plugging and take corrective action before a condition such as loss of scrub liquid flow develops .
  • Another feature which is included in the instrumentation and control system is a two-level alarm and protective action procedure .
  • the first indication is an alarm which notifies the operator of the problem. If corrective action is not taken , a second alarm, set slightly further outside the control band is actuated . This second alarm is accompanied by automatic protective action .
  • Still another feature of the instrumentation and control system which leads to improved relability is the remote control capability of the system. All equipment can be remotely valved in or out and remotely started . This feature minimizes the operator action away from the control room.
  • the safe operation of the system is provided by control sequencing which prevents improper operation and effect automatic system shutdown if system parameters are not maintained within the prescribed limits .
  • FIG 15A schematically depicts one type of shredder which may be used in conjunction with the present invention wherein a manually controlled motor driven shredder mechanism enclosed within a hopper delivers shredded solid combustible waste as sized piieces to a shredder conveyor.
  • the conveyor is likewise motor driven and manually controlled. Dust generated within the shredder hooper is drawn into a manually controlled motor driven dust collector.
  • the collector delivers solids derived from collected dust to the conveyor.
  • signals from the interlock system will shut off, in timed sequence, the shredder motor, the dust collector motor and the shredder conveyor motor and isolation valve 167. It is preferred that upon complete shredder shut down, no dust remain in the dust collector and no shredded waste on the shredder conveyor, which might jam the conveyor at. start up.
  • top and bottom internal, temperatures of the solid waste tank 168 are monitored as is the pressure within the bottom of the tank. Excessive temperature at either location indicates combustion within the tank and causes a signal to issue to the instrumentation system and a fire extinguisher to automatically issue water or other fire retarding liquid through a solenoid valve 700 to the tank 168 and the screw conveyor 172.
  • a hand control may be used to achieve the same result manually. All motors may be started and stopped manually using the associated hand control and each is remotely monitored through an instrumentation system, hereinafter explained in greater detail.
  • the rate at which the bottom augers deliver shredded waste from the tank 168 to the screw conveyor 172 is varied up and down according to the mean temperature of the fluidized bed so that the proper amount of waste reaches the vessel for efficient, continuous incineration.
  • all remote operated valves may be manually controlled by the associated hand control and each is remotely monitored through the instrumentation system.
  • the motor for the bottom augers, the screw conveyor motor and the blower motor, respectively, may be remotely shut offthrough the control system, as may isolation valves 170 and 173 and solenoid valve 702.
  • the screw conveyor 172 exhibits excessive temperature, the operator is informed by the issuance of an alarm. If pressures within the solid waste tank 168 become excessively high, an alarm is issued. This is also the case if the air flow rate and/or air pressure within the pneumatic conveyor 108 becomes unacceptably low. Furthermore, if the amount of waste in the tank 168 becomes excessively low or high an alarm issues.
  • the liquid waste control and instrumentation system as presently preferred, illustrated in Figure 16, specifically monitors and regulates (using the exterior heater) the interior temperature of the liquid waste tank 192, monitors the inlet and outlet pressures of the pump 198 and regulates the rate at which the pump 198 displaces liquid waste into conduit 112. It monitors the pressure differential across the strainer 201, to detect clogging, monitors the flow rate and pressure within liquid waste conduit 112 and monitors and regulates the flow rate of the liquid waste atomizing air in conjunction with the flow rate of liquid waste in conduit 112. The atomizing air is mixed with the liquid waste at or adjacent to the bed 66.
  • the agitator within the tank 192 is operated by a manually controlled motor and the strainer bypass flow control valve 197 is automatically controlled by flow in conduit 203.
  • the motor for strainer 201 is also manually controlled.
  • the interior temperature of the tank 192 is continuously recorded, and it is regulated by use of the exterior heater, which is controlled by the associated temperature indicator controller.
  • An alarm is issued when and if the tank temperature is unacceptably low.
  • the level of liquid waste in the tank is automatically controlled by a level controller and the flow control valve 698 in conduit 164. Alarms are issued if the tank, level becomes too high or too low. If the level in tank 192 continues to drop below the low level alarm point, the low low alarm point will be reached and a second alarm is sounded. At the second alarm corrective action is automatically initiated to open valve 698 and shut off pump 198. If the high level alarm point is exceeded a second alarm is sounded at a slightly higher level in tank 192 and corrective action is initiated by closing valve 698.
  • Alarms are caused when the tank temperature becomes excessively low, when the pressure differential is high across the strainer of valve 201, when the pressure is high in conduit 112 on either side of the isolation valve 708 located downstream of pump 198 and when the flow rate of atomizing air in conduit 115 is low.
  • the rate of liquid displacement caused by pump 198 is stopped at the occurrence of any one of four events, i.e. (a) low pressure at the influent to pump 198, (b) high pressure at the effluent of pump 198, (c) inadequate flow at the flow element contained within conduit 112, and (d) an inadequate flow rate of the air within conduit 115 used to atomize the liquid waste.
  • isolation valve 199 It is preferred upon closure of isolation valve 199 that heated water displaced across isolation valve 706 be used to purge waste from conduits 112 and 203 for a limited time.
  • Figure 17 illustrates the presently preferred instrumentation and control system applicable to the resin and sludge waste feed. From Figure 17, it is apparent that all valves may be manually and remotely controlled. Further, the interlock system provides for the selective and independent control of isolation valve 184, the isolation valve 187 at the effluent of the dewatering tank 186, the isolation valve 718 in conduit 194, the isolation valve 716 in the loop conduit which spans between feed pump 188 and dewatering pump 196, the isolation valve 711 disposed downstream of pump 188 the isolation valve 710 contained in conduit 110 and the isolation valve 717 which controls the input of kaolin clay from tank 719 along conduit 721.
  • the interlock system may signal closure of the valve 187 disposed at the effluent of tank 186, the isolation valve 718 disposed in conduit 194 and the isolation valve 716 disposed in the mentioned feed pump—dewatering pump conduit, and the isolation valve 711 downstream of pump 188.
  • the interlock logic monitors the motor rotation of the agitator of tank 186 and controls the starting and stopping of pumps 188 and 196.
  • the rate of the pump 188 is adjustable to control flow of material into the fluidized bed.
  • the air flow within conduit 110 is monitored continuously and the two level, alarm approach previously mentioned is utilized. More specifically, when the air flow, rate drops below the desired value, an annunciator is sounded to prompt corrective action by the operator. If corrective action is not taken by the operator and air flow drops further, a second alarm is caused to issue and the control system shuts down the mentioned components associated with the resin and sludge waste feed.
  • the interlock system regulates air flow at the solenoid valve in conduit 110.
  • the pressure within conduit 110 is communicated to the operator by a pressure indicator.
  • the level of waste in the dewatering tank 186 is monitored and valve 184 controlled to correct highs and lows.
  • demineralized water is used to purge residual waste from the conduit 194 , and the conduit downstream of the pump 188.
  • Figure 18 depicts presently preferred controls and instrumentation for the fluidized bed vessel. Specifically, the temperature of the effluent off-gas in conduit 100 is monitored and recorded. Similarly, the pressure differential across the depth of the bed is monitored and recorded.
  • the isolation valve 141 at the bottom of the vessel 30 is remotely manually or automatically controlled to regulate the removal of used bed material from the vessel, while the flow control valve 132 at the cooling air effluent may be subjected to remote manual or automatic control to insure adequate cooling thereby maintaining the temperature of the inner shell 50 at about or below 1200°F.
  • the pressure at the top of the vapor space 64 is monitored and used to regulate the amount of ambient air added at the off-gas blower inlet and thereby regulate the vapor space pressure.
  • an alarm is issued to the operator.
  • the temperature is monitored at three separately spaced sites within the vapor space 64 of the vessel 30. Each temperature is recorded. In the event that any two of the three sites monitored indicate an unacceptably high temperature, an alarm is issued. Two out of three sensors are required to read a high temperature to initiate an alarm or shutdown. In this way, malfunctioning of any one temperature sensor does not effect protective action. If for some reason the corrective action taken by the automatic temperature control system (or by the operator) is ineffective and the temperature continues to rise, when a predetermined high temperature is reached a second alarm issues and the control system initiates shutdown of the process.
  • the temperature of the bed 66 within the vessel 30 is likewise monitored at three separate sites. The continuous temperature at each site is recorded. If any two of the three monitoring sites indicate an unacceptably high bed temperature, initial alarm is sounded. Two out of three sensors are required to read a high temperature to initiate an alarm or shutdown. In this way, malfunctioning of any one temperature sensor does not effect protective action. If, for some reason, the corrective action is not taken and the temperature continues to rise, when a predetermined high temperature is reached, a second alarm is issued and the control system shuts off the fuel oil and waste feed systems. The same two level concept is used for the two low temperature alarms and the two low temperature protective actions in the event the bed temperature at two or more of the mentioned sites falls below an acceptable temperature.
  • a temperature indicator controller senses the mean temperature of the bed and causes the magnitude of heat generated by preheat burner 124 ( Figure 19) to be appropriately adjusted up or down by regulating the magnitude of fuel supplied from fuel source 150 to the heater 124. All sensors exposed within the interior of the bed are formed of material which will withstand the high temperature and corrosive atmosphere.
  • FIG. 19 illustrates presently preferred instrumentation and controls for the fluidizing air preheat burner 124 , as currently preferred .
  • the motor powering blower 126 may be manually started and stopped and is also stopped by the control system.
  • Both the fluidizing air blower 126 and the shutoff solenoid valve 720 located within the liquid fuel line 104 are controlled manually by the operator or by command signals from the control system.
  • the flow control valve disposed within the liquid fuel line 104 is regulatedby the bed temperature sensing circuit previously described .
  • the pressure and temperature within the conduit 122 are monitored by pressure and temperature indicators .
  • the pressure within the conduit delivering atomizing air to the preheat burner 124 is continuously monitored and , if unacceptably low, an alarm is issued to the operator .
  • the temperature of the burner fluidizing air effluent is monitored and recorded or displayed on an indicator , depending upon the setting of the associated selector switch . If the effluent temperature of the burner 124 is unacceptably high, an alarm is issued to the operator .
  • the flow of the three branches of conduit 122 (supplying cooling , combustion and overfire air) is monitored .
  • the combustion and cooling flow within said conduit 122 is recorded and is used as a basis for regulating the low control valve disposed downstream in the cooling air conduit. If the flow rate is unacceptably low, an initial alarm is issued. If the related flow control valve (or the operator) does not cause corrective acton to be taken and the flow rate continues to drop , corrective action is taken automatically by the control system to avoid damage or excursion of system paramters outside acceptable levels .
  • the flow in overfire air conduit 102 is monitored and recorded. The results of the monitoring are used to continuously regulate the flow control valve 137. If such flow control valve regulation fails, and the flow rate in conduit 102 becomes unacceptably low, the operator is informed by the issuance of an alarm.
  • a flow rate monitoring and control system is provided for the fuel, combustion air and atomizing air flow rates.
  • the atomizing air and combustion air are supplied to the burner at rates which are proportional to the fuel flow.
  • the fuel and the atomizing air flow rates are continuously recorded.
  • propane or like fuel from a pilot fuel tank be communicated to the burner chamber across a solenoid valve 722, which in turn is controlled by the control system.
  • the liquid fuel from conduit 104 is introduced into the burner chamber.
  • the supply of propane is terminated once the main flame is proved.
  • the burner flame in the burner chamber is continuously monitored.
  • FIG. 2024 illustrate presently preferred instrumentation and control for the off- gas system. More specifically, the temperature of the off- gas effluent from the dry cyclones 320 are monitored at conduit 330, and recorded or visually displayed depending upon the setting of the associated selector switch.
  • the isolation valves 325 and 331 are remotely controlled in such a way that when one set is open the others are closed. Accordingly, solid particles may be delivered to product pots 329 across either valve 325 and contained therein until product pot 329 is full at which time they are placed in container 326 across valves 331, valves 325 being closed during the interval of time required to dispense solid particles to container 326.
  • a vibrator 333 is associated with each pot 329 to aid in discharging solid particles therefrom.
  • Each dry cyclone 320 comprises an annular air space through which cooling air is caused to pass. The magnitude of cooling air so displaced is regulated by interconnected remotely controlled flow control, valves in the cooling air effluent conduits of the dry cyclones 320.
  • the temperature within the off-gas effluent conduit 342 from quench tank 332 ( Figure 21) is monitored and either recorded or visually displayed to the operator depending upon the setting of the associated selector switch.
  • An unacceptably high temperature causes an initial alarm and, if no corrective action is taken by the operator and the temperature continues to increase, a second alarm is issued and corrective action is automatically initiated.
  • the abnormally high temperature condition causes the addition of demineralized water to conduit 336 through valve 734. This is introduced into the quench tank 332 to reduce the temperature thereof. Zn addition, the mentioned valve may be manually controlled by the operator.
  • the pressure within the scrub solution conduit 336 is continuously monitored and visually indicated to the operator- An unacceptably low pressure causes an alarm to issue to the operator.
  • the flow rate within the scrub solution conduit 336 is continuously monitored and recorded. The results of the monitoring are used to regulate the flow control valve in conduit 336 so that appropriate adjustments occur to maintain the desired rate of flow. If abnormally low flow rates occur, an alarm is also issued to the operator. Demineralized water is used across solenoid valve 734 to replace scrub liquid in conduit 336 and tank 332 if flow of scrub liquid fails.
  • an isolation valve 732 is disposed in scrub solution return line 340 and is remotely operated automatically by the control system or manually by the operator to control the level of liquid in the tank 332.
  • Figure 22 illustrates instrumentation and controls presently preferred for the venturi scrubber 344 and the wet cyclone 350 .
  • the pressure differential across the venturi influent conduit 342 and the wet cyclone effluent conduit 358 is continuously monitored and recorded . If the indicated pressure differential is abnormally low , the operator is informed by the issuance of an alarm.
  • the throat 346 of the venturi scrubber 344 is variable , as previously mentioned , and is preferably set from time to time by an associated remote manually controlled motor .
  • the pressure within the scrub solution influent conduit 336 is continuously monitored and the operator is visually informed hereof . If the pressure within conduit 336 falls below an acceptable level , the operator is informed by the issuance of an alarm.
  • the flow rat.e of scrub solution within conduit 336 is continuously monitored and may be recorded if selected by the selector switch. This continuous flow rate information is used to regulate the flow control valve contained within conduit 336 .
  • a two level alarm system is provided . An initial alarm issues if the flow rate within conduit 336 is unacceptably low . If no adequate operator correction or feedback correction occurs and the flow rate continues to drop a second alarm is issued and the control system causes corrective action to be taken by initiating demineralized water addition through solenoid valve 736 .
  • a manual override is provided for controlling the flow control valve disposed in conduit 336 . Upon termination in the flow of scrub liquid , a solenoid valve 736 is caused to be opened by an interlock control solenoid and demineralized water is caused to replace scrub liquid in conduit 336 and scrubber 344 .
  • the temperature at the influent conduit 358 to the entrainment separator 359 is continuously monitored and either , recorded or visually displayed for the operator , depending upon the setting of the associated selector switch .
  • the temperature of the off-gas effluent in conduit 366 issuing from condenser 360 is continuously monitored and recorded.
  • the indicated temperature information is used to regulate the temperature control valve disposed in the cooling water effluent conduit 364 , which will alter the cooling effect occuring in condenser 360 to produce an off-gas effluent therefrom having an acceptable temperature .
  • the off-gas pressure differential across the mist eliminator 370 between conduits 366 and 376 is continuously monitored and the results visually displayed for the operator. An unacceptably high pressure differential causes an alarm to issue to the operator .
  • Water is manually caused to flow across related solenoid controlled valves to purge the entrainment separator and mist eliminator at those points in time when off-gas flow therethrough is terminated.
  • the SO 2 adsorber bed temperature is continuously monitored with visual display and recording if the selector switch is so positioned .
  • the pressure differential across this bed is continuously monitored and displayed for the operator . If the pressure becomes unacceptably high an alarm is issued .
  • the off-gas flow rate in conduit 377 downstream of SO 2 adsorber tank 379 and in advance of heater 378 and the temperature at the effluent of the heater 378 are continuously monitored.
  • the operator is informed of any unacceptably low flow rate by the issuance of an alarm and operator or interlock corrective action is initiated .
  • the indicated temperature is continuously recorded. If the temperature at the effluent of heater 378 becomes unacceptably high , an initial alarm is issued. If no operator correction takes place, and the temperature continues to rise , a second alarm follows and the existence of abnormality is sensed, by the control system which automatically causes an appropriate reduction in the heat generated by the heating element within the heater 378 by shutting it off .
  • a manually controlled valve accommodates drain of accumulated water within the heater 378 .
  • each HEPA filter 380 and 388 The pressure across each HEPA filter 380 and 388 is continuously monitored and the results visually displayed for the system operator . Any abnormally high pressure differential , indicating a partial clogging of the filter is brought to the attention of the operator by the issuaance of an alarm.
  • the pressure differential across the iodine adsorber 384 is likewise monitored with alarm capability .
  • the moisture content within the off-gas displaced through conduit 382 is continuously monitored and visually displayed for the system operator. Any abnormally high moisture content is brought to the attention of the operator by the issuance of an alarm.
  • the aforementioned iodine adsorbent is selectively communicated to the iodine adsorber across a control valve .
  • the iodine adsorber may be manually drained .
  • Temperature of the adsorber is continuously displayed for the operator .
  • the motor driving the off-gas blower 392 may be controlled and regulated either manually or by signals received from the interlock logic .
  • a pressure control valve regulates the magnitude of ambient air added to conduit 394 at the blower 392. This ambient air addition is controlled by pressure sensed at the top of the bed vessel 30, as previously described.
  • the flow rate in conduit 394 is continuously, monitored and recorded. If an unacceptably low flow rate occurs, an alarm is issued and protective action is taken. The remaining motors of the off-gas system cannot be started in this condition. To insure reliability, a second alarm issues if the flow rate continues to drop and interlock logic corrective action is once more initiated.
  • the conduit 394 is provided with a sample tap for periodic analysis, of the off-gas.
  • the radioactive level of the off-gas in conduit 394 is continuously monitored and recorded. The operator is informed of any unacceptably high radioactive levels by the issuance of an alarm and if corrective action is not taken by the operator and the radioactivity level continues to increase, the control system takes corrective action. Specifically, the entire system is shut down.
  • FIG. 25 illustrates further instrumentation and controls, presently preferred for use in conjunction with the scrub solution system.
  • the pH of the scrub solution returned to the solution tank 338 by conduit 337 is continually monitored and used as a basis to control the flow rate of new scrub additive solution introduced into the tank 338 through conduit 396. More specifically, the information obtained with the pH monitoring is used to not only control the flow rate by regulating the solenoid valve 726 contained within conduit 396 but to control the rate at which the motor driven pump 728 in conduit 396 is caused to displace new solution to the tank -338. If the pH of the return scrub solution in conduit 337 is outside the acceptable range, the operator is informed by the issuance of an alarm.
  • the temperature within the tank 338 is continuously monitored and, alternatively, either recorded or visually displayed for the operator.
  • the level of the contents within the tank 338 is continuously monitored and the results visually displayed. If the level is high or low, an alarm issues for the operator to initiate corrective action. If adequate correction does not occur and the level continues to drop, a second alarm issues and the interlock system causes corrective action to be taken.
  • the tank may be manually drained across a drain control valve.
  • the pressure at the effluent of tank 338 in conduit 398 is continually monitored and the results visually displayed for the operator.
  • the pressure differential across the strainer 402. is continuously monitored. The result is visually displayed for the operator and in the event' the pressure differential is unacceptably high, the operator is informed by the issuance of an alarm.
  • the strainer 402 is preferably a motor driven strainer, which motor is manually controlled for self cleaning.
  • the motor driving pump 400 may be either controlled manually or automatically by the control system.
  • the flow control valve in conduit 164 may be regulated so as to continuously deliver a predetermined amount of scrub solution to the liquid waste tank for processing as waste in the manner herein described, thereby preventing excessive accumulation of undesired constituents within the scrub solution.
  • the temperature at the influent of the quench tank in conduit 336 is continually monitored and the results recorded.
  • the results are also used to continuously regulate a temperature control valve disposed in the cooling water conduit servicing the heat exchanger 404. In this way any excessive temperature is immediately reduced.
  • the pressure of the scrub solution delivered to the quench tank and venturi scrubber is continuously monitored in line 337. If unacceptably low, the operator is informed by the issuance of an alarm. The results thereof are utilized to continually correspondingly regulate the pressure control valve disposed in conduit 337.
  • demineralized water is manually caused to purge residual scrub liquid from the conduits downstream of the tank 338.
  • Figures 2740 illustrate a presently preferred interlock logic system used in conjunction with the instrumentation and controls heretofore described.
  • the logic is conventionally supplied with electrical power and the logic components appearing in Figures 28-40 are commercially available and their respective operations are outlined in Figure 27.
  • annunicators and/or light indicators shown in the drawings may be utilized as desired. Whether shown or not, it is desirable to use annunicators in the present system to signal the following events:
  • a fire extinguishing function is automatically caused to occur when an unacceptably high temperature at the top and/or bottom of the bin 168 has been sensed.
  • the fire extinguisher valve 700 is then automatically opened and a fire extinguishing substance is introduced into the bin 168 and into the housing of the screw conveyor 172.
  • the extinguisher manual reset button closes the valve and resets the controls for future operation.
  • the feed screw conveyor 172 In order for solid waste to be fed to the fluidized bed vessel 30, it is necessary that the feed screw conveyor 172 be operating. For feed conveyor 172 to operate, it is necessary that the bin inlet isolation valve 167 be closed and that the bed temperature be within it's operating range (not high or low). Fluidizing air flow must not be low.
  • the manual start solid waste feed button and solid waste mode select button must each be actuated. Also, the temperature within the bin 168 (top and bottom) must not be high.
  • the bin temperature manual override button must be activated if top or bottom bin temperature is high.
  • isolation valve 170 is automatically opened and the screw conveyor 172 begins to rotate to deliver shredded solid waste to pneumatic conveyor 108, provided the screw conveyor power is on, the solenoid valve 702 in conduit 108 is open and the blower 174 is on. Valve 702 is open when valve 170 is open and the pressure within the bin 168 is not high.
  • valve 702 in conduit 108 closes if the pressure in the solid waste bin 168 is high and if the valve 170 closes.
  • the vertical auger within the tank 168 is caused to rotate when the auger power is on, the manual local stop and lock out button has not been actuated, and the screw conveyor 172 and/or the shredder conveyor are on.
  • the live bottom augers rotate at a controllable rate and solid waste is fed to the screw conveyor 172 when the live bottom auger power is on, the vertical auger is turning, the feed screw conveyor 172 is operating and the bottom auger stop and lock out botton has not been actuated.
  • Rotation of the live buttom augers automatically terminates without delay if the live bottom auger local stop and lockout control is actuated, the conveyor 172 stops or any of the previously mentioned conditions for closing valve 170 occur.
  • valve 167 When the shredder conveyor is on, valve 167 is automatically caused to be open. Valve 167 is also automatically opened when all of the following conditions exist: valve 170 is closed, the temperature of bin 168 is satisfactory, the shredder start button has been actuated and the level of solid waste in the solid waste hopper 168 is not high.
  • valve 167 be open, all of the conditions for valve 167 to be open exist, the content of tank 168 not be high, the temperature of the shredder bin (top and bottom) not be high, that the stop shredder hand control not be actuated and the shredder local stop and lockout control not be actuated.
  • the shredder conveyor When the valve 167 closes, the shredder conveyor immediately shuts off.
  • the shredder conveyor also stops without delay when the shredder conveyor local stop and lockout control is actuated.
  • the shredder conveyor stops on a delayed basis when the temperature of the solid waste bin (top or bottom) becomes high, the stop shredder control is actuated or the shredder local stop and lockout control is actuated, or the contents of the tank 168 becomes high. The delay allows the shredder conveyor to discharge all shredded waste thereon.
  • Shredding occurs only when: shredder power is on, the shredder door is closed, the vertical auger in the tank 168 is on, the shredder conveyor is on and the dust collector is on.
  • the dust collector operates only when the dust collector power is on, the dust collector local stop and lockout button has not been actuated and the shredder conveyor is on.
  • the liquid waste vessel delivery system previously described in conjunction with Figures 3, 4 and 16 utilizes one or more nozzles 114 at all times. In some cases it is desirable to have a vessel with two nozzle capacity wherein either one or both vessel nozzles 114 may be utilized at any point in time.
  • a vessel with two nozzle capacity wherein either one or both vessel nozzles 114 may be utilized at any point in time.
  • Such a system is illustrated in Figures 29, 29A and 29B and presumes to independent channels for delivering liquid waste each having a pump, a feedback loop, a strainer and related valves, etc. as previously described.
  • the remaining features of each channel of the dual channel liquid waste delivery system of Figures 29, 29A and 29B will become readily apparent from the following description.
  • a hand operated nozzle selector switch 704 is provided whereby liquid waste may be caused to be delivered to nozzle #1, nozzle #2 or both. Since the steps of operation are identical for each channel or nozzle, only the steps in conjunction with the operation of nozzle #1, will be described, it being understood that the operation of nozzle #2 and nozzles #1 and #2 concurrently occur in the same fashion as described, once the nozzle select switch 704 is properly set.
  • the associate speed controlled feed pump 198 be operating and that the related isolation valve 199 be open.
  • Valve 199 is automatically opened when the nozzle select dial 704 has been set, the mode select actuator has been set in the liqud waste position, the preheat burner 124 is on, the start liquid waste feed control has been manually actuated, the contents of the liquid waste tank 192 are not low or low low, the fluidizing air flow is not low, the vessel bed temperature is not low, low low or high, and the stop liquid waste feed control has not been actuated. Furthermore, the pump influent pressure low low and/or the pump effluent pressure high high conditions cannot exist if valve 199 is to open.
  • Isolation valve 199 closes at once on feed pump inlet pressure low low, feed pump outlet pressure high high, preheat burner not on, liquid waste mode not selected, bed temperature low low, day tank level low low, liquid waste feed stop hand control or nozzle not selected.
  • Valve 199 causes, on a time delay basis, termination of the operation of pump 198, and opens the isolation valve to the heated water causing conduit 112 to be purged for a predetermined interval of time, after which the heated water isolation valve 706 is automatically closed.
  • the valve may also be manually closed by actuation of the stop heated water flush manual control.
  • Pump 198 continues to operate, on a time delay basis during the heated water flush cycle. Alternatively, the heated water flush may be achieved by manual actuation of the start heated water flush control.
  • valve 199 For normal operation of feed pump 198 it is not only necessary that valve 199 be open but further that any of the mentioned conditions for closing valve 199 not exist, that electrical power be supplied to the pump, that the pump local stop and lockout control not be actuated, that the influent pressure of the pump not be low low, and that the effluent pressure of the pump not be high high.
  • the strainer 201 is caused at predetermined time intervals to be wiped to prevent clogging.
  • the feed pump 188 is disabled (and resins-sludge feeding discontinued) if air flow in the conduit 110 becomes low low, or (on a time delay basis) if the bed temperaturebecomes low low, the stop feed control is actuated, the local lockout control is actuated, the agitator in the tank 186 is shut off, the contents of the resin feed tank 180 become low, or the preheater burner 124 is shut off. Any of the mentioned time delay conditions also will cause valve 187 to close.
  • Operation of the pump 188 also requires that the isolation valve 711 adjacent pump 188 be open.
  • the isolation valve 711 is caused to be opened when the mode select switch is set to the resin-sludge feed position, the bed temperature is not high or low, the fluidizing air flow is not low, the start feed button has been actuated, the agitator in tank 186 is operating, the contents of the resin feed tank 186 are not low and the preheat burner is on.
  • the isolation valve 711 is closed by any of the above mentioned events which cause the pump 188 to stop on a time delay basis and by a low low air flow in conduit 110.
  • Resin and sludge waste is transferred from tank 180 to tank 186 when the contents of the resin feed (dewatering) tank 186 are not high, the isolation valve 184 is caused to be open, the open fill valve control has been actuated and the agitator in tank 186 is rotating. Agitator rotation Occurs after the agitator start control has been actuated and electrical power is supplied to the agitator.
  • the agitator is stopped when either the stop agitator control is actuated or the agitator local stop lockout control is actuated.
  • Isolation valve 184 is caused to close when the close fill valve control has been manually actuated or when the content in tank 186 has become high.
  • Dewatering occurs in conduit 194 when the dewatering pump 196 is operating, which requires that agitator in tank
  • Dewatering may occur either during resin feeding to the vessel with isolation valve 187 open or when resin feeding is not occuring with isolation valve 187 closed.
  • the isolation valve 716 in the conduit loop between pump 188 and conduit 194 is caused to be open and isolation valve 718 closed whereby dewatering occurs through the mentioned conduit loop to the pump 196.
  • the isolation valve 718 in conduit 194 is caused to be open with the pump 196 operating so that dewatering occurs directly through conduit 194. In either case, dewatering terminates when pump 196 is stopped, which causes valves 716 and 718 to close.
  • solenoid valve 720 in conduit 104 must be open, a flame must exist in the burner and the pilot fuel solenoid valve 722 must be closed. The normal operation of the burner is terminated when any of the above-mentioned conditions cease to exist.
  • the solenoid valve 720 in conduit 104 is opened when the fuel pump is on.
  • the fuel pump is on when a flame or pilot light is detected by the flame sensor, electrical power is being supplied to the fuel pump and none of the following conditions exist: the vessel vapor temperature is not high high (on the previously described two of three basis), the bed temperature is not high high (on the preveiously described two of three basis), the fluidizing air flow is not low low, the quench tank off-gas temperature is not high high, the venturi scrub liquid flow is not low low, the burner stop control has not been actuated and the pump local stop and lockout control has not been actuated. If any of the described conditions change, the fuel pump is turned off, the solenoid valve 720 in conduit 104 is closed and combustion within the burner 124 stops.
  • Burner start-up requires that the burner start control be manually actuated, and that the venturi scrub flow not be low, the quench tank scrub flow not be low, the fluidizing air flow not. be low, the bed temperature not high (on a two of three basis) and the vessel vapor temperature not high (on a two of three basis). Then, burner start is delayed for a two minute interval of time while an air purge occurs thorugh conduits 102 and 122 as well as the burner itself. Thereafter, the burner pilot ignites and propane or the like is automatically caused to oxidize within the burner 124 for an interval of 12 seconds. At the end of a two minute 12 second delay, the interlock causes the solenoid valve 720 to open, the fuel pump to operate and valve 722 to close whereby normal burner operation occurs.
  • Figure 32 illustrates the presently preferred fluidizing air blower126 interlock logic.
  • the motor driven fluidizing blower 126 For combustion air to be delivered through conduit 122 to the burner 124, the motor driven fluidizing blower 126 must be operating. This operation occurs only when the following conditions exist: electrical power is being supplied to the blower, the stack off-gas flow rate is not low and the fluidizing air blower start control has been actuated.
  • the fluidizing blower 126 is stopped if the hand control blower local stop and lockout control is actuated, the stack gas flow rate becomes low low or the fluidizing air blower stop control is actuated.
  • Figure 33 illustrates the presently preferred interlock logic for the dry cyclones.
  • Th product pots or containers 329 receive solid particles separated from the off-gas in the two dry cyclones 320 when the cyclone discharge valves 325 are opened. This occurs when the hand control for opening the valves 325 is actuated and both cyclone discharge valves are opened and both solid effluent isolation valves 331 are closed. Actuation of the manual control closes the valves 325, which terminates discharge into product pot 329 .
  • the discharge valves 331 are caused to be open when the valves 325 are closed.
  • the valves 325 are closed manually when the hand control is appropriately actuated.
  • a vibrator be utilized in conjunction with the hopper 329 on those occasions when discharge valves 331 are open.
  • the off-gas reheater 378 which is temperature controlled, is caused to operate only when the heater temperature is not high high, the heater off-gas flow rate is not low and electrical power is being supplied to the heater.
  • the heater is shut off when and if the flow therethrough is low or the temperature thereof is high high.
  • off- gas flow is caused to occur through blower 392 when electric power is supplied to the motor thereof, the start control is actuated and the scrub liquid flow in either the venturi scrubber or the quench tank is not low.
  • the blower operation is terminated if the scrub liquid flow in either the quench tank or the venturi scrubber becomes low low, the stop blower control is actuated, the blower local stop and lockout control is actuated or the radiation level of the off-gas to the stack is high high and the diverter valve 724 in conduit 394 has been actuated to deliver the off-gas to the stack.
  • the blower shuts off due to excessive radiation in the off-gas.
  • the pump 400 is caused to operate only if electrical power is delivered to the pump, the start scrub pump hand control has been actuated and the scrub liquid level in the tank 338 is not low.
  • the pump 400 is stopped if any of the following events occur: actuation of the pump local stop and lockout control, actuation of the stop scrub pump control, .the level of liquid in the tank 338 becomes low low or the level of scrub liquid in the quench tank becomes high high.
  • Scrub additive is added to the scrub tank 338 from a suitable source, e.g. a tank, through conduit 396 only when the solenoid valve 726 in conduit 396 is opened.
  • the solenoid valve 726 is caused to be open only when power is being supplied to the adjacent pump 728, the scrub liquid pump 400 is being operated, the scrub liquid being returned to the tank 338 through the conduit 337 has a low pH and there is an ample supply of additive at source thereof.
  • the additive pump is shut off when the pH of the scrub liquid being returned to the tank 338 through conduit 337 has a high pH, if the contents in the source become low, electrical power to pump is discontinued or the scrub liquid pump 400 is stopped.
  • the source of scrub liquid additive is maintained at an elevated temperature through the use of a heater 7,30.
  • the heater 730 is caused to be on only if electrical power is supplied thereto, the temperature of the additive liquid therein is low and not high and the contents thereof not low.
  • the heater 730 is shut off when the temperature of the additive liquid therein becomes high.
  • the presently preferred interlock logic for the scrub li ⁇ uid drain of the quench tank 332 is illustrated in Figure 37.
  • the quench tank isolation valve 732 in conduit 340 must be open to accommodate return of scrub liquid from the quench tank to the tank 338.
  • the mentioned isolation valve opens when either the level of scrub liquid in the quench tank is high or the quench tank drain level control is manually actuated.
  • the isolation valve 732 is closed when either the quench tank scrub liquid level becomes low or the hand control is actuated.
  • the presently preferred interlock logic for the demineralized water purge of the quench tank is illustrated in Figure 38.
  • the solenoid valve 734 is interposed between the source of demineralized water and the conduit 336 is caused to be open and demineralized water is directed into conduit 336, through the quench tank 332 and along the conduit 340.
  • the demineralized water solenoid valve 734 is caused to open either by appropriate actuation of the related hand control or by reason of the fact that the quench tank off—gas temperature goes high high.
  • the solenoid valve 734 is caused to close thereby terminating the demineralized water purge when either the ⁇ uench tank off-gas temperature goes low or the related hand control is actuated.
  • FIG 39 The presently preferred interlock logic for purging the venturi scrubber with demineralized water is illustrated in Figure 39.
  • Demineralized water is introduced into the conduit 336 upstream of the venturi throat 346 when the demineralized water solenoid valve 736 is open. This opening is on a time delay basis and occurs only when the scrub li ⁇ uid pump 400 is on, and the venturi scrub liquid flow is low low.
  • appropriate actuation of the associated hand control for the venturi demineralized water will cause the mentioned flow to occur.
  • Such demineralized water flow is terminated by appropriate manual manipulation of the related hand control or stopping of the scrub liquid pump 400.

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  • Incineration Of Waste (AREA)

Abstract

A fluidized bed radwaste volume reduction system, including method and apparatus. Low level radioactive waste divided into three classes combustible solids, ion exchange resins and filter sludges, and liquids emanating from a reactor facility are respective introduced at separate intervals of time through an integrated waste influent system into a common fluidized bed vessel (30) where volume reduction either through incineration or calcination occurs. Addition of a selected substance to the ion exchange resin before incineration inhibits the formation of low-melting point materials which tend to form clinkers in the bed (66). Solid particles are scrubbed or otherwise removed from the gaseous effluent of the vessel in an off-gas system, before the cooled and cleaned off-gas is released to the atmosphere. Iodine is chemically or physically removed from the off-gas. Otherwise, the only egress materials from the volume reduction system are containerized dry solids and tramp material. The bed material used during each mode may be circulated, cleaned, stored and exchanged from within the bed vessel by use of a bed material handling system. An instrumentation and control system provides operator information, monitors performance characteristics, implements start up and shut down procedures, and initiates alarms and emergency procedures during abnormal conditions.

Description

FLUIDIZED BED VOLUME REDUCTION OF DIVERSE RADWASTES
Background Field of Invention
The present invention relates generally to disposal of waste material and more particularly to a novel system , comprising method and apparatus , for safe and efficient fluidized bed volume reduction of various low level radioactive waste emanating from a nuclear reactor facility .
Prior Art
During the last few years , there has been a significant increase in the use of nuclear energy to generate electricity . This has been accompanied by increased treatment and disposal problems of the radioactive waste (radwaste) materials . One significant problem is that , due to the increase in the number of operating facilities , there is a great demand on available space at license disposal sites . Moreover , it is believed that selection of new commercial disposal sites in the future will involve close government supervision and strict regulation .
In particular , it is believed that government regulatory agencies will hereafter review and monitor low level radwaste disposal installations , Requirements to obtain a license will probably become more stringent .
A major concern in disposal is the safety of transporting the treated waste to its final disposal site . In dealing with this concern , it is desirable to reduce the volume of the waste as much as possible along with increasing the stability of the materials .
Another major problem in the treatment of wastes generated in nuclear plants is that several types of waste are produced which differ significantly in chemical and physical characteristics one from another . Heretofore , several waste treatment facilities have respectively treated the several radwastes emanating from a reactor facility. Incomplete or lack of treatment of some of the reactor facility radwastes has been a long term problem, especially in respect to radioactive ion exchange resin wastes. Current disposal practice for resins and sludges involve drumming and solidification without volume reduction.
Fluidized beds have been separately employed for liquid calcination or combustible waste incineration in industrial plants for several years. For instance, see Richard C. Corey, Principals and Practices of Incineration, Wiley Interscience, New York, 1969, page 239. Moreover, fluidized bed calcination or radioactive wastes was broadly developed during the period of 1952 to 1959 at the Idaho National Engineering Laboratory. Use of calcination for liquid radwaste reduction was broadly employed in an engineering scale facility, the Waste Calcining Facility (WCF) , at the Idaho Chemical Processing Plant in 1963. The WCF results are summarized in a publication by one of the present applicants, T.K. Thompson, entitled "Fluidized Bed Calcination of Radioactive Wastes Using In-bed Combustion Heating" , Nuclear Technology, Volume 16, Nov. 1972, pp. 396405. The WCF effort, as revealed in the publication, was technologically valuable, although certain problems, limitations and deficiencies were conceded or identified. More specifically, the WCF work admitted the state of the art (prior to the present invention) to be independent and separate status for incineration and calcination of various radwaste, with no suggestion or provision for achieving both processes in one radwaste treatment fluidized bed. Further, the WCF admitted lack of application to resin incineration.
A batch operated fluizied bed calciner was designed and built as part of the Midwest Fuel Recovery Plant (MCRP) at Morris, Illinois for General Electric Company.
A batch calcination process was employed on a fully radioactive basis in the WSEP program from about 1966 to about 1970. This process was developed at Oak Ridge National Laboratory for the specific purpose of solidification of high level radioactive liquid waste but did not employ a fluidized bed process.
Incineration per se of solid combustible radioactive wastes has been in use as a disposal technique since 1948 when a pilot plant incinerator and off-gas clean-up system was built at Mound Laboratory. The earlier systems were adaptations of standard refuse incinerators and demonstrated that considerable volume reduction in waste handling was possible. Data taken in the early 1960 's at the General Electric Atomic Power Equipment Department in San Jose, California showed that about 99% of the radioactivity of the incinerated wastes remained in the ash. Similar data was reported from an incinerator at Pratt and Witney Aircraft where approximately 99.1 to 99.98% of the radioactivity remained in the ash. For a discussion of various incinerators for radwaste treatment, attention is directed to B.L. Perkins, "Incineration Facilities for Treatment of Radioactive Wastes: A Review", LA-6252, Los Alamos Scientific Laboratory, Los Alamos, New Mexico, 1976. Prior art incineration of solid combustible radwaste presented serious questions respecting versatility, safety, efficiency and operation on a day to day ongoing basis.
Fluidized beds , which have been previously employed solely to convert liquid waste streams including radioactive streams to solid particles, were composed of the resulting solid products from previous drying or calcining a liquid waste stream similiar to the one being treated. The difficulty encountered was that the fluidized particles were simultaneously subject to growth, from deposition of new liquid waste on the surface where the water flashed off leaving a layer of resulting solids, and size reduction caused by the "self—grinding" action of the particles colliding with each or with any solid surface to which they were exposed. The simultaneous growth and size reduction processes were very critical to proper operation because fluidizing properties were a function of particle size. While some particle growth could be tolerated, large particles required high fluidizing velocities which were detrimental to the operation of other system components. On the other hand, if the bed particles became too small, they would be blown out of the fluidized bed (elutriated) as the fluidizing air superficial velocity approached the terminal velocity of the particles in the vessel or as the fluidizing air rate was reduced, a loss of capacity resulted. Accordingly, in such systems, due to the delicate balance between growth and size reduction, it was necessary to continually monitor the particle size distribution of the fluidized bed media and make adjustments in operating conditions to control the particle size and particle growth phenomena to assure proper particle size.
This particle growth and size reduction phenomena was greatly influenced by the chemical characteristics and composition of the liquid waste stream being converted to the solid. For instance, if the total solids content (dissolved and undissolved) of the waste was less than a certain value (dependent upon the chemical identity of the liquid waste), it was not possible to grow fluidized bed particles. This is due to the size reduction (attrition) rate being greater than the size increase (growth) rate because of the small amount of solid-building material present in the liquid waste stream.
This dependency of such fluidized bed calcination or evaporation processes upon the chemical identify of the liquid waste was a major disadvantage which required extremely close process supervision to assure proper operation.
Moreover, the above—type calcination process could not handle very dilute liquid waste streams in view of the mentioned particle size control problem. In a booklet by the assignees of the present application entitled "RWR—1 Radioactive Waste Reduction" which was available in October. 7-11, 1975, at the Nuclex Exhibition, a trade conference in Switzerland, a system was suggested wherein an afterburner was required after the incinerator/- calciner. According to the present invention, in view of the particular controls on certain process parameters, it is no longer necessary to employ a separate afterburner. Any afterburning needed occurs directly in the incinerator/- calciner rather than after leaving the incinerator/calciner and after a subsequent cyclone treatment. The above booklet did not disclose the necessary detail concerning the fluidized bed which are essential to the present invention.
Brief Summary and Objects of the Invention In brief summary, the present invention comprises a system, including method and apparatus, for fluidized bed volume reduction of the low level radioactive wastes emanating from a nuclear facility, such as a light water nuclear power reactor. A single fluidized bed vessel is used in any one of three modes of volume reduction upon command, i.e. for (a) incineration of solid combustible radwaste, (b) incineration of ion exchange resins and filter sludges (these two materials are considered the same throughout this document) and (c) calcination of liquid waste. Extraordinary safety and efficiency are achieved, with the discharge from the fluidized bed volume reduction system being strictly limited to (a) clean off-gas emissions to the atmosphere, (b) dry granular anhydrous radwaste solids derived from processing the off-gas to capture particulate matter and (c) spent bed media and tramp material segregated from the bed. A novel integrated waste influent system injects only one of the mentioned radwastes at any one point in time, while a single improved off-gas system processes and cleans off-gas derived from the fluidized bed treatment of each of the mentioned radwastes. Uniquely, the following features are or may be provided: (a) removal of iodine from the off-gas at an adsorber site before the off-gas is released to the atmosphere; (b) recirculation and/or storage of bed materials respectively used during each mode of operation; (c) abrasive scouring of any crust formation on the bed particles; (d) an off-gas venturi scrubber, providing a variable pressure drop; (e) bed material processing for clinker and tramp removal; (f) additive to increase the melting point of the residue that form during the incineration of ion exchange resins and filter sludges; (g) novel preheating auxiliary heating of the bed; (h) an air cooled corrosion resistant fluidized bed vessel which dramatically increases life expectancy; (i) operation of the vessel at less than atmospheric pressure; (j) a unique automated instrumentation and remote control system to provide operator information, monitor performance characteristics, implement start up and shut down and cause the issuance of alarms (under abnormal conditions) ; (k) a scrub system for effective removal of particles from the off-gas in a simplified fashion.
With the foregoing in mind, it is a primary object of the present invention to provide a novel fluidized bed system, including method and apparatus, for safe and efficient volume reduction of radwastes.
An additional important object is the provision of an improved system, including method and apparatus having a common fluidized bed vessel by which most low level radioactive wastes from a nuclear facility, including resins and sludges, solid combustibles, and liquids are incinerated or calcined at successive time intervals.
An additional dominant object according to the present invention is the provision of an integrated waste storage and handling system for selective displacement of the various radioactive wastes from a reactor facility at different intervals of time for volume reduction in a common fluidized bed vessel throucrh incineration and calcination. Another principal obj ect is the provision for recir culation , cleaning , and storage o f bed material for each o f three modes of radwaste fluidized bed incineration and calcination .
An additional paramount obj ect is the provision of a radwaste volume reduction system having a single improved off-gas system by which cooled and cleaned off-gas is released to the atmosphere following processing by which solids are removed from the off-gas , independent of the particular type of radwaste from which the off-gas comingled with solids is originally derived.
These and other obj ects and features of the present invention will be apparent from the detailed description taken with reference to the accompanying drawings .
Brief Description o f the Drawings
Figures 1 , 1A , IB , 1C and 1D are diagramatic representations of the various types of waste emanating from different light water power reactors ;
Figure 2 is a layout showing the relationship of Figures 3-6 ;
Figure 3 is a cross section of a combination incinerator/- calcinator fluidized bed vessel , according to the present invention ;
Figure 4 is a schematic representation of a feed system , according to the present invention;
Figure 5 is a schematic representation of a bed material storage and handling system, according to the present invention;
Figure 6 is a schematic representation of an off-gas treatment system, according to the present invention ;
Figure 7 is an exploded perspective of a venturi scrubbier having a variable throat ;
Figure 8 is an enlarged exploded cross section taken along line 8-8 of Figure 7 ; Figure 9 is an enlarged cross section taken along line 9-9 of Figure 7;
Figure 10 is a side elevation, with parts broken away for clarity, of the assembled venturi scrubber of Figure 7;
Figure 11 is an enlarged side elevation, with parts broken away for clarity, of the variable throat mechanism of the venturi scrubber of Figure 7;
Figure 12 is an enlarged cross section of another variable throat mechanism for a venturi scrubber;
Figure 13 is a perspective of an iodine, adsorber according to the present invention;
Figure 14 is an elevation of one of two screen mechanisms used within the iodine adsorber of Figure 13;
Figures 15A, 15B, and 16-26 are schematics of a presently preferred instrumentation and control system for use in conjunction with the apparatus of Figures 3-6;
Figure 27 is a symbol chart for interlock system of the presently preferred instrumentation and control; and
Figures 28—39 are schematics of a presently preferred interlock system for use in conjunction with the mentioned instrumentation and control and the apparatus.
Detailed Description of the Illustrated Embodiments
General
The present invention can be more fully understood by reading the following description in conjunction with the Figures which illustrate preferred apparatus according to the present invention. Also, the system, including apparatus and method, will be described in terms of treating diverse low level radioactive waste materials (radwastes) emanating from a single nuclear reactor. Although it is understood that multiple reactor stations can be serviced if capacities permit. When desired , any of the radwastes can be pretreated prior to introduction into the feed system . For instance , relatively large non-combustible solids such as tools , piping, and the like must be removed by conventional methods .
The overall system , generally designated 28 , illustrated in Figures 2-6 broadly comprises (a) a novel single stage/multiple incineration and calcination fluidized bed vessel , generally designated 30 (Figure 3 ) , (b) an integrated diverse waste feed system, generally designated 32 (Figure 4) , which receives various radwastes from nuclear reactor plant systems , generally designated 34 , independently stores and to some extent processes the radwastes and selectively delivers any one of the radwastes only to the vessel 30 for a desired interval of time , (c) bed storage and handling systems , generally designated 36 and 38 , respectively (Figures 3 and 5) , and (d) an off-gas treatment system , generally designated 40 (Figure 6) .
The overall system provides , for the first time , one apparatus whereby the volume of the various radwastes emanating from a nuclear reactor plant is reliably , safely , and efficiently reduced via a single stage fluidized bed reactor using , at separate times , two separate modes of incineration (one for solid combustible radwaste and one for resin and sludge radwaste) , and , at still other times , one mode of calcination ( for liquid wastes on the order of 1 to 25% dissolved solid content by weight) . The volume reduction, for example , for sludge is on the order of 5 to 1 and for solid combustible waste is on the order of 80 to 1. Only concentrated and anhydrous solids derived from incineration and calcination and a clean off-gas egress from the overall system. Iodine is removed from the off-gas .
Resin radwaste , for example , may be spent ion exchange resin beads or powdered resins . Solid dry combustible radwaste may be rags , anti-contamination clothing , paper , wood , mops , lubricating oils , cleaning swipes , plastic gloves , and other dry laboratory waste . This type of waste normally has a much lower specific radioactivity than wet waste .
Sludge is derived from reactor liquid waste system filters . Liquid wastes result from reactor water treatment processes , equipment drains and miscellaneous clean-up systems .
By way of illustration only, reference is made to Figure 1, which identifies the various non-gaseous non-fuel wastes emanating from 1000 Mw(e) light water reactors. The types of wastes shown in Figure 1 are generally typical of all commercial power reactors. Heretofore, no single process vessel radwaste system was proposed or provided for incineration and calcination of all of the indicated wastes. The system can be configured to process all of these wastes in a single vessel.
Items of hardware, contaminated tools and the like are conventionally removed from the wastes and are not processed by the fluidized bed reactor 30.
It is presently preferred that the volume reduction system be sized so that by continuously operating no more than 75% of the time all of the amenable radwaste emanating from a single reactor facility will be thoroughly incinerated or calcined in the fashion herein described. Of course, the capacity may be varied. By knowing the magnitude of gross radwaste and the quantity of each type emanating from the mentioned reactor facility and the rates at which the in cinerator/calciner is able to selectively dispose of the wastes, the waste—handling system and the fluidized bed incinerator/calciner and the off-gas treatment system may be appropriately sized. Naturally, the greater the capacity, the less operating time required, exclusive of the time required to start the system up and shut it down (assuming less than continuous year around operation).
It has been found to be acceptable to size the overall system to accommodate incineration of 150 pounds per hour of solid combustible diry waste, 200 pounds per hour of a mixture of resins and sludges with transport water and 41 net gallons per hour of liquid waste, realizing that the respective categories of waste are processed through the calcinator/incinerator 30 at separate intervals of time, but that the incinerator/calcinator (after start up) is operated substantially continuously, except for the time required for transition from one form of waste to another.
Benefits of the present invention include cost savings associated with: (a) construction of only one waste incineration/calcination facility as opposed to several, (b) fewer waste shipping containers, (c) transportation of less waste to a disposal area, (d) handling of less waste and (e) less waste placed at the disposal site. Increased safety in processing, handling, transporting, and disposing of the various radwastes and reduction in radiation exposure are also attained. All applicable governmental regulations are met or exceeded.
The Fluidized Bed Vessel
Reference is now made primarily to Figure 3 , which illustrates in cross section the fluidized bed incinerator/- calciner 30, sometimes also referrend to as the process vessel. The incinerator/calciner 30 comprises an elongated hollow interior 50, defined by an interior metal shell 52. The metallic enclosure or shell 52 comprises a right circular metal cylinder 54, a top 56 integral with and completely enclosing the top of the right circular cylinder 54 and a cone shaped bottom 58 terminating in a central axially disposed downwardly—directed bed material, clinker, and tramp removal opening 60. The opening 60 is defined by a relatively short vertical chute 62.
The shell 52 defines a vapor space 64 disposed above a fluidized bed 66, which bed is contained in the lower portion of the interior shell 52. The vertical wall 54 (a right circular cylinder) of the shell 52 is interrupted by an off-gas port 70 and an overfire air introductory port 72 for vapor space combustion. A bed material introductory port 76 accommodates injection of bed material directly into the bed 66 (but which could be placed above the bed for gravity discharge onto the top of the bed). Waste introduction ports 78/80 and 82 also exist in the cylinder 54. While only one port 82 is illustrated, it is to be appreciated that, as hereinafter more fully explained existence and use of several such ports are preferred.
The tapered vessel bottom 58 is interrupted by a side port 86 (by which fluidizing air is introduced into the bed 66).
The incinerator/calcinator vessel 30 substantially concentrically from the interior radially outwardly comprises seriatim, a cooling space 90, an intermediate metallic shell 92, a layer of relatively low temperature insulation 94 and an outside metal covering shroud or sheath 96. Each of the mentioned components accommodates various piping, plumbing and conduits, which service the vessel through the previously mentioned ports in the inner shell 52. These include an off-gas duct 100 (communicating with port 70) , an overfire combustion air conduit 102 (passing through the port 72) , a bed material chute 106 (passing through port 76) , a solid combustible waste conduit 108 (passing through port 78) , a resin and sludge waste conduit 110 (passing through the port 80) and one or more liquid waste conduits 112 (passing through ports 82 and terminating in atomizing nozzles 114).
In addition, a fluidized air duct 122 passes through the port 86 and attaches to fluidizing manifold 116 which contains fluidizing orifices 118. The plenum 116 comprises part of an air delivery system, generally designated 120, which is serviced by a suitable combustion chamber or heater 124 and an air blower 126. Fuel is conducted into the combustion chamber 124 through opening 74 by a fuel pump 154 from a fuel tank 150 through pipe 152. Fuel oil, kerosene or the like contained within tank 150 is available along conduit 152 to variable speed fuel pump 154 and conduit 104 for injection into the combustion chamber 124 during, for example, calcination.
The metal of the shells 92 and 96 as well as the insulation layer 94. fit snugly against the various conduits mentioned above (which conduits pass through the entire composite wall of the vessel 30). These same conduits are joined to the metal shell 52 so as to be air tight, accommodating utilization of a slightly negative operating pressure within the interior 50 of the process vessel.
The intermediate metal layer 92 merges into a central upwardly-directed cooling air effluent conduit 130 which is axially aligned with the vessel 30. Air from blower 131 (or any other suitable source) is caused to be displaced along conduit 133 and along air space 90 to service the vessel cooling needs. Flow is controlled by valves 132 and 135. This heated air is then exhausted through conduit 134 and through valve 132. An auxiliary blower may be used in conjunction with the conduit 134 to force exhaust cooling air out the stack.
Also air from source 126 may be caused to pass along conduit 102 (when valve 137 is open) for enhancing combustion of volatile matter in vapor space 64 of the vessel 30, which combustion occurs spontaneously, or to increase volume through off-gas duct 100. Valve 137 is closed when combustion in vapor space 64 is not desired or when no increase in volume through duct 100 is desired.
While mild sheet steel is adequate for the central layer 92 and the exterior shroud 96, use of mild steel for the interior shell 52 has been found inadequate. It has been discovered that utilization of an alloy of nickel, chromium, molybdenum, niobium and tantalum provides resistance to oxidation at high temperature, protection against crevice and pitting corrosion, prevention of sensitization of the material during welding , and enhancement of the overall corrosion resistance of the interior liner. 52 of the vessel 30 . Commercially available alloy of 50-80% nickel , 15-23% chromium , 2-19% iron , 0-9% molybdenum, 0-6% niobium and tantalum has proven most satisfactory . The selected material does not require precipitation hardening heat treatment. Halide (chloride) intergranular corrosion is minimized . Adequate high temperature corrosion resistance overall is provided up to 1400 °F , it being presently preferred to size the air cooling fan 131 and the related air passages and valves so as to limit the temperature of the interior shell 52 to a maximum temperature of 650 ° C during vessel operation .
During incineration , the fluidized bed operates within the range of about 800 °C to 1200 ° C and curing calcination , within the range of about 200 °C to 550 °C . In calcination hot off-gas is passed from the vessel 30 at a temperature only slightly below that of the bed temperature .
The pressures in the incinerator/calciner 30 , in the waste feed system , and in the off-gas clean-up system are maintained below ambient pressure in all operating modes . For example , pressure ranges from 4—6% psi below ambient at the inlet to the off-gas blower to just under atmospheric pressure in the fluizied bed .
Three different vessel operating modes are utilized to process the range of radwastes from a given reactor , i . e . liquid waste calcination , solid dry combustible waste incineration, and ion exchange resin and filter sludge incineration . The incineration modes are separated one from the other . Mode selection instrumentation and control is provided so that only one operating mode can occur at any one interval of time . Each mode of operation is accommodated by the integrated waste feed system , the bed material handling system and the off gas system. When operating in a given mode , all other modes are rendered inoperable . Start up in all three modes requires preheating the bed 66 to the operating temperature by use of the burner 124 and fuel from source 150 .
In either incineration mode , the basic process is one of combustion. Efficient combustion is achieved by provision of adequate air (oxygen) and high temperatures . Almost all of the combustible waste feed is non-radioactive organic material which is intimately mixed with trace quantities of radioactive particles . The organic molecules are broken down into non-radioactive carbon dioxide and water and allowed to pass off as harmless, gases . The bulk of the waste is thus removed , leaving the radioactive material and ash behind.
The bulk of the activity in many types of waste are in nuclides of the elements such as strontium, manganese , iron , cesium and cobalt which will form oxides in the hot oxidizing atmosphere of the incinerator/calciner . These oxides form solid particles which are removed in the off-gas system. The efficiency of the present volume reduction process is based upon the attained complete combustion and effective separation of the solids from gases in the effluent . The separation takes place in the off-gas system and is discussed hereinafter .
Fluidized-bed combustion is very efficient. The constant agitation of the bed particles with the small pieces or droplets of the waste feed material results in a rapid rise of the waste material temperature . The fluidized air which maintains the bed in its fluid state provides an ample supply of oxygen, and combustion may be enhanced by supplying overfire air above the top of the bed. The thermal inertia of the bed material itself means that the system is relatively insensitive to short term variations in the exact caloric content of the feed.
The rubbing action of the bed wears off the brittle oxidized surface which forms on the larger waste particles and virtually insures that the center of these particles do no remain unαxidized. This bed rubbing action also wears off any liquid coatings which may form on the bed particles . These coatings form because some wastes, such as plastic, may melt before oxidizing.
The combustible waste feed, fluidizing air, and overfire air flow rates are automatically controlled to maintain a predetermined bed temperature. The burner is used to establish the desired operating temperature within the vessel prior to introduction of the dry waste. With the initiation of waste feed the burner is turned off and the temperature is maintained by the heat released from the burning waste.
Adequate air for incineration of ion exchange resins and filter sludges is also achieved by automatic control of flow rates of the resin/sludge feed and the fluidizing air. The temperature of the fluidized bed is automatically controlled by hot gas input from the burner 124 to assure complete combustion during resin and filter sludge incineration. In either mode of incineration, the dry product (ash) is elutriated out of the fluidized bed and into the off-gas system, where the dry product accumulates in a product container. Any clinkers that form and any tramp material introduced with the combustible waste pass from the vessel bed 66 through the bottom opening 60. In the calcination mode, the basic process is one of evaporation or drying. Heat is used to drive off water as a vapor, leaving behind an incombustible residue. Spraying the liquid waste into the process vessel creates droplets which are heated rapidly by their contact with the hot bed particles. As the temperature rises the water evaporates leaving dried waste material on the individual bed particles. This dried waste material is ground off the bed particles by the agitation of the bed and is elutriated from the vessel to the off-gas system. Any clinkers pass from the vessel bed through opening 60.
The calcination process is continuously endothermic, and heat is supplied by the heater 124 by combustion of fuel oil obtained from tank 150. In this mode the fluidized bed temperature is controlled by the fuel burner. The liquid waste and fluidizing air flow rates along with burner input are automatically controlled to maintain bed tempreature. Since there is no waste combustion in the overfire area in this mode, no overfire air is required.
The Waste Feed System
The various radwastes emanating from reactor plant 34 (generally shown in Figure 1} are delivered on a segregated basis to the waste feed system 32. For purposes of simplicity Figure 4 illustrates solid combustible waste being communicated from the reactor plant 34 to the waste feed system 32 along conveyor 160, with resin and sludge waste being likewise communicated via conveyor 162 and liquid waste via conveyor 161. It is to be appreciated that while conveyors 160, 162 and 161 are illustrated as comprising tubing or conduit, any suitable form of conveyance may be used for delivering the segregated wastes mentioned to the waste feed system 32.
The feed system 32 to the incinerator and calciner vessel 30 (shown in Figure 3) is arranged for feeding each of the three spearate types of waste to the vessel 30 at separate times. Of course, this feed system is exemplary of the myriad systems which may be employed depending upon the exact wastes being treated.
In handling the combustible waste, it is desirable to reduce the size of the individual particles of waste, such as by shredding at shredder 166 or otherwise, so that they can be efficiently transported into and thoroughly incinerated in the bed 66. The maximum size of the particles must be smaller than the inside diameter of the transport piping leading to the process vessel and is limited, when a pneumatic feed is employed, by the flow rate of the carrier gas. The presently preferred maximum dimension of pieces emitted from shredder 166 is on the order of about 2". Alternatively, reduction of particle size when desired can be done by way of a shredder located after storage hopper 168, where the solid combustible waste is accumulated pending delivery to vessel 30. It is preferable that shredding and. loading of combustible waste into tank 168 occur simultaneously to minimize handling and personnel exposure to radiation.
The storage hopper 168, shredder 166 and conveyor 160 are sealed from the atmosphere to guard against possible radiological contamination of the surrounding area. The hopper is sealed from the shredder when the shredder is not in use by valve 167.
The combustible waste is illustrated as being conveyed seriatim to incinerator/calciner 30 through a live bottom 170 in the storage hopper 168 and along a srew conveyor 172 and a pneumatic tubular conveyor 108. Pneumatic conveyor 108 is serviced by blower 174. Other types of conveyance can, of course, be employed. As mentioned, in order to insure against the possibility of outleakage of radioactive contamination from the radioactive material in the system, the vessel 30, which may be sized for 150 pounds per hour of combustible waste, is maintained at a pressure lower than ambient pressure and the feed is to a portion of the vessel wherein the pressure is lower than ambient pressure. In addition, the screw feeder 172 may be isolated vy valve 173, disposed in conduit 108, which is used to provide a positive air-tight seal when the combustible feed system is not in use. The shredder 166 and the tank 168, as well as accompanying feed conduits, are preferably constructed of carbon steel.
Resins and sludge are conducted through conduit 162 and isolation valve 714, introduced into tank 180 and collected therein after which valve 714 is manually closed. It may be desired to collect resin in a separate tank from the sludge. As mentioned, typical resin and sludge feeds include cation and anion exchange resin beads, powdered resin filter precoat materials (e.g., "Powdex") , nonresinous filter precoat materials (e.g., "Solkafloc", diatamaceous earth and the like) , along with varying amounts of water. The resin and sludge are conveyed via conduit 182 through valve 184 to a mixing and dewatering tank 186. From tank 186, the material is then conveyed through valve 187 by a positive displacement, metering pump such as a progressive cavity pump 188, whereafter it is injected by air from compressor 189 into the vessel 30 via conduit 110. The distance between tank 186, valve 187, and pump 188 must be held to an absolute minimum as must the distance from pump 188 to conduit 110.
In the dewatering and mixing tank 186, the waste is mechanically agitated which helps prevent bridging, compaction, or adhesion to the tank walls. After dewatering, the slurry desirably includes only as much water as is necessary to maintain a slurry capable of being readily pumped. Feed slurries may contain from 30% to 80% by weight of solids after dewatering in tank 186.
Water which is obtained from dewatering can be returned to the slurry pumping system as make—up water or can be pumped to the liquid waste storage tank 192 via conduit 194 by dewatering pump 196. Screen 185 prevents resins from being drawn out of the tank 186 by the pump 196.
In some situations the addition of kaolin clay is desirable to combine with low melting point ashes to increase their melting point and thus prevent slagging. The clay is added to tank 186 through valve 197 and conduit 199 from tank 201.
The resin and sludge waste is introduced into vessel 30 at a position in the bed area 66 wherein the pressure is below atmospheric. The equipment for the mixing and dewatering of the resin and sludge waste is preferably constructed of stainless steel.
Liquid waste is introduced into liquid waste tank 192 via conduit 161 and/or the recycle conduit 194. Liquid waste is pumped from tank 192 by pump 198 across valve 199, self-cleaning strainer 201 and along conduit 112 to vessel 30. Atomizing air is introduced into the liquid waste as it is conveyed to vessel 30. Compressor 113 is schematically shown as providing the mentioned air. It is preferred that the liquid waste be introduced into the vessel 30 through one or more air atomizing nozzles 114. Nozzles 114 can be remotely cleaned mechanically or with hot water and air. The liquid waste should be at a temperature above the saturation temperature of the dissolved solid wastes at the concentration in the solution. This inhibits subsequent plugging of process piping, valves, nozzles and the like. For this purpose, all tanks, valves, and piping are heat traced to maintain solution temperature.. Flow is controlled to thenozzles by by-passing a portion of the output of pump 198 through conduit 203 by opening or closing valve 197 in conduit 203 or by varying pump 198 rpm. The flow through this valve is directed back into tank 192. Particles that do not pass through strainer 201 are thus recycled and may be redissolved or broken up by pump 198.
Typical liquid waste can contain about 75% to about 99% water by weight along with such soluble materials as sodium sulfate, boric acid, and the like. Some specific liquid waste compositions include: (a) Boiling Water Reactor (BWR) waste from a forced recirculation evaporator which normally contains about 75% water, about 22.9% sodium sulfate, about 2% sodium chloride, and 0.1% miscellaneous ingredients, (b) Pressurized Water Reactor (PWR) waste from a forced recirculation evaporator which normally includes about 73.4% water, about 14.9% sodium sulfate, about 9.6% ammonium sulfate, about 2% sodium chloride, and about 0.1% miscellaneous ingredients, and (c) boric acid waste from a forced recirculation evaporator which contains about 87.9% water, about 12% boric acid, and the remainder miscellaneous ingredients. It is desirable that the boric acid and ammonium sulfate in the liquid waste be neutralized with a base to prevent the formation of stickey or volatile boron compounds after introduction to the process vessel 30. The above percents are all by weight.
Since the different types of feed (combustible, resin/- sludge or liquid waste) require different temperatures of treatment depending on whether calcination or incineration is needed, only one stream is introduced into the vessel 30 at any one time and is treated therein. Accordingly, when one of the streams is being introduced into the vessel 30, the other two waste streams are closed off from the vessel.
Bed Materials
As mentioned, the present invention employs the same fluidized bed vessel for both calcination and incineration. While it is sometimes appropriate to use a single bed material for incineration and calcination, ordinarily separate bed materials for each mode are preferred. Switching of bed materials comprises part of the present invention. Each fluidized bed material is a fluidizable, granular material which is resistant to oxidation, agglomeration, and attack by chemicals such as acids and bases at temperatures up to 1200°C. The use of such an inert material is advantageous in eliminating problems existent in prior fluidized bed incinerators which required a close observation of the system to assure proper operation. This was due to the fact that the particle growth and size phenomena as discussed hereinabove had to be properly controlled. Bed materials, such as quartz, which do not possess the above properties would not be successful in the present invention.
The preferred inert bed materials possess the following characteristics:
Hardness (Moh) 6.0 - 9.0
Specific Gravity 3.2-3.9
Coefficient of Thermal 0.0083 Expansion (in/in/°F) Fusion Point 2300 - 3200°F
(1260 - 1760°C)
Particle size 0 - 5 — 1.5 mm.
Some examples of bed materials which can possess all of the above properties include chrysolite , olivine , kyanite , corumdum, mullite and alumina.
Manufactured bed materials may consist of particles of alumina or porcelain or similar material that have been pelletized and sintered or formed and crushed to the desired size . Natural material such as orthosilicates or corundum may be used.
For special applications requiring an inert surface , the particles may be coated with a resistant material priorto charging to the fluidized bed . In some applications the coating may be applied in the fluidized bed using the heat of the process vessel itself .
The size of the bed particles in accordance with the present invention is not greatly affected by contacts in the bed due to the hardness of the material from which the bed particles are made and the soft friable nature of the dry calcine. The system is also largely independent of the chemical composition of the waste because of the inertness of the bed . This is important in an application such as a commercial electrical generating station radwaste volume reduction system because the chemical composition of the waste could comprise a number of corrosive and otherwise active ingredients .
Bed Material Storage and Handling System
The system also provides a new bed make— up capability to compensate for bed losses through elutriation and occasional clinker formation . The system remotely draws a metered quantity of material from the new bed storage tank and inj ects it into the fluidized bed during operation .
Bed media that has been exposed to the chemical environment of the calcination mode cannot be exposed to the high temperatures of the incineration mode without excessive clinker formation. This condition is created because the high temperature of the incineration mode exceeds the melting point of residual salts deposited on the bed media during calcination. A similar situation does not occur when converting from the incineration mode to the calcination mode. Such a restriction requires, that the bed handling design include the capability to remove the bed used in calcination and recharge with appropriate bed material prior to start-up in the incineration mode. In some applications it may be economically justifiable to simply dispose of the calcine bed and recharge with fresh bed material. Normally, however, it will be necessary to maintain a separate bed inventory for operation in each mode and to provide the necessary handling capabilities for bed change-outs and storage.
If allowed to accumulate within the bed region, clinkers and tramp material will interfere with the fluidization of the bed media. To provide continuous, extended process operation, these materials are removed from the bed region without disrupting the fluid bed operation. This is accomplished by extracting portions of the bed from the region below the fluidizing air distributor, screening and storing or reinjecting the bed material back into the vessel. The equipment is designed to screen the entire operating bed inventory through a predetermined interval, or cycle.
To minimize impact on equipment availability, bed change-out with minimum interference during the mode transition period is provided. The entire bed may be removed in a relatively short time. A rapid bed dumping capability is provided to withdraw a resin incinerating bed in the event of a loss of fluidizing air. The bed outlet valve 141 is controlled to evacuate the bed from the vessel 30 before any type of permanent harm results. Such an event would otherwise result in a solidification of the bed within a short period of time.
The bed handling system is designed to accommodate radioactively contaminated bed material. The handling and storage equipment is totally enclosed and operated at less than atmospheric pressure to preclude the release of airborne contamination . To minimize exposure to operating personnel , the system is remotely operable so far as practicable .
It is preferred, indeed essential on occasion , that screened bed material be conveyed to its appropriate storage location. Since the same bed material handling system is used to transport both incineration and calcination bed material , it is self-cleaning to preclude mixing residual bed material with that handled in a subsequent mode . The conveyor and its interfaces are totally enclosed , to preclude any release of radioactive contamination . The temperature requirements of the conveyor are considerably relaxed from that of the bed removal system due to the fact that the bed will be allowed to cool in the vessel and enroute . The temperature of the bed during transport does not exceed 300 °C .
Reference is now made to Figures 3 and 5 which illustrate the presently preferred bed material storage and handling systems 36 and 38 , respectively . It is presently preferred to provide a fresh bed material storage tank 256 , into which any desired bed material may be initially placed through the top opening 258 thereof . The selected bed material in tank 256 is introduced through isolation valve 264 , effluent conduit 262 , inclined gravity conveyor 106 into the vessel 30 . Once the vessel 30 comprises a bed 66 of satisfactory height , the valve 264 is selectively operated to meter additional fresh bed material into the vessel to maintain the desired bed depth notwithstanding loss of bed material through attrition. At the end of any incineration or calcination cycle, fresh bed material remaining in tank 256 may be drained therefrom through valve 260 and out spout 266 into a suitable container . No radiation exposure will result since the fresh bed material is not radioactive . Thereafter , another bed material may be introduced into the tank 256 to service the requirements o f the ensuing incineration or calcination cycle .
The bed material storage system 36 comprises the previously mentioned inclined gravity conveyor 106 . Separate storage tanks 242 and 244 are illustrated as being provided to receive , store and selectively issue calcination bed material and incineration bed material , respectively . Each of the tanks 242 and 244 are adapted to receive recirculated bed material as hereinafter more fully described . Each tank 242 and 244 is equipped with selectively operated influent and effluent isolation valves 248 and 250 , respectively . Each tank 242 and 244 is intended to preferably store one complete bed and each tank is in selective communication with 'the sloped gravity conveyor 106 across the associated valve 250 and an effluent conduit 252 . Reclaimed bed material is delivered to the tanks 242 and 244 , respectively , across the associated valve 248 and along an influent conduit 254 . Since the used bed hoppers 242 and 244 will store one complete bed each , no metering capabilities are required for the associated isolation/feed valves . The new bed hopper 256 , however , must be able to feed discrete amounts of bed material for make-up during operation and therefore has metering capabilities . It is presently planned to allow the recycled bed material to cool to 300 °C prior to transport for storage . The hoppers 242 and 244 are therefore designed for 300 °C .
As illustrated in Figures 3 and 5 , the bed material handling system 38 is interposed between the bottom discharge conduit 62 of the vessel 30 and four sites , i . e . a tramp material storage tank 280 , emergency bed material drum 281 , and the recycled bed material storage tanks 242 and 244 . In normal operation , the bed material is suspended above the fluidizing manifold 116 by the air coming out the orifices 118 . Obj ects heavier than the particles o f the bed material , such as tramp material , will fall through the manifold and accumulate in the area just below the orifices 118. From time to time conveyor 272 may be operated to remove the accumulation. To cease processing, the injection of feed is terminated and the fuel oil burner is turned off. Fluidizing air continues passing through the bed, keeping the bed suspended and cooling it. When the bed material has cooled to 300 °C , the fluidizing air is shut off and the bed handling system is turned on. Bed material migrates by force of gravity downward in the interior shell 52 of the vessel 30, the bed material (containing tramp material and clinkers) passes from the vessel 30 through the bed material effluent conduits 62 and 273 where normally the bed material is intercepted and displaced along an inclined conveyor 272 under force of a rotating bed material withdrawal auger or screw feed 274. The bed material is thus conveyed directly over collector 276 where recyclable bed material is caused to fall by gravity through a screen area at the top of the collector with reamining tramp material and clinkers being displaced by the screw conveyor 274 along the conveyor 272 past the collector 276.
At the screening section 276 of the conveyor 272, the screw flights change from solid to a helical wire brush to prevent damaging the screen by jamming clinkers or tramp material between the screen and the screw. In addition, the wire brush helps keep the screen section clean. Downstream of the screen section the screw is again in solid flights to convey clinkers and foreign material to the tramp material storage tank 280. The conveyor is inclined to enhance selfcleaning.
The clinkers and tramp material, accordingly, fall by force of gravity along chute 278 into tramp material storage tank 280. Clinkers accumulated in tank 280 are selectively discharged thereform, after cooling, across valve 282 into a clinker container 284 for solidification and subsequent transportation to a burial or other suitable radwaste disposal site. Reusable bed material accumulated in collector 276 is displaced to the bed material storage system 36 where it may be stored or recycled directly to the fluidized bed vessel 30 . More specifically , the bed material accumulated in collector 276 moves by force of gravity along bed material effluent conduit 288 to the bottom area of a bucket or screw elevator conveyor 292. An endless belt of buckets or vertical screw conveyor 294 , in a fashion, well known in the art , delivers the reclaimed bed material upward through the entire length of the elevator conveyor 292 , where the reclaimed bed material is communicated to a screw conveyor 296. Screw conveyor 296 displaced the reclaimed bed material along a conveyor 298 to the appropriate one of the recycled bed material storage tanks 242 and 244 , depending upon the bed material being processed by the bed material handling system 38 . This communication occurs across the associated valve 248 and along the influent conduit 254 associated with the bed material storage tank being used . The remaining valve 248 remains closed.
When it is desired to recycle the bed material directly to the vessel 30 , the reclaimed bed material passes from the collector 276 down bed effluent conduit 288 to the bucket conveyor 292. It is moved up to the screw conveyor 296 which displaces it through valve 297 and through the conduit 299 and into the inclined gravity conveyor 106 and from thence into the bed 66. The conveyor 292 may be replaced by a pneumatic conveyor powered by an air blower , if desired .
During the combustion of some filter sludges the fluidized bed 66 will increase in depth. In order to maintain the proper bed depth it will be necessary to remove some bed material with the bed removal system as previosuly described and store it in the appropriate storage tank 242 or 244 . This is accomplished by running the system until the bed level is satisfactory with valves 297 and 250 closed and the appropriate valve 248 open . As part of the rapid dump system the diverter valve 141 is normally positioned such that the normally removed bed material moves by gravity along conduit 273 to conveyor 272 and then through the system as previously described. In the event of an emergency, such as loss of power while combusting resins, the valve 141 is repositioned so that the bed material flows by gravity through conduit 279 into drum 281 which is sized to hold the total bed. The diverter valve 141 is actuated with loss of power while in the resin combustion mode by a return spring to the emergency position. This feature is also used when disposing of a used bed that is no longer servicable for some reason. Valve 141 is de-energized and the bed is dumped into drum 281 for disposal.
The Off-Gas System
Air is blown into the bottom of vessel 30 via blower 126, conduit 122 and plenum 116 to maintain the bed in its fluidized condition. This also supplies the oxygen necessary for combustion. Moreover, during incineration, additional overfire air is injected via conduit 102 above the bed to enhance complete combustion. In view of the interrelationship between the height of the vessel 30 and the flow rates employed during operation, the volatile particles elutriated from the bed remain above the bed in the vessel for a sufficient amount of time that any necessary afterburning for efficient combustion occurs before the elutriated noncombustible particulate matter is exhausted through hot gas duct 100 into twin dry cyclones 320 of the off-gas treatment system 40 shown in Figure 6. The vessel height and additional air eliminate the need for an afterburner. The static bed height for processing the amounts of materials discussed hereinabove can be from about 13 to about 26 inches.
As mentioned, the heat for the calcination and for preheating the bed is provided by heater 124 using liquid hydrocarbon fuel from tank 150. Ordinarily, with the bed at operating temperature introduction of waste to be incinerated supplies sufficient fuel to maintain the incineration process. If not, in a given situation additional heat can be supplied from heater 124.
The table below sets forth some approximate typical operating conditions for the various operating modes for dry cyclone 320 of the dimensions given.
Inlet duct - .60 ft X .62 ft (long dimension is vertical) Parallel Twin Cyclone I.Ds - 17 inches Calcination of liquid wastes
O2 _ 394 Ib/hr
N2 - 2008 Ib/hr CO2 - 159 Ib/hr
H20 - 499 Ib/hr
Solids - 99 lb/hr
Total - 3159 lb/hr
Temperature - 300°C
Pressure - 13.5 psia
CFM - 1573
Incineration of resins/filter sludges
O2 _ 67 lb/hr
N2 - 979 lb/hr
CO2 - 219 lb/hr
H20 - 211 lb/hr
SO2 - 8 lb/hr
N02 - 3 lb/hr
Solids - 4 lb/hr
Total - 1491 lb/hr
Temperature - 825°C
Pressure - 13.5 psia
CFM - 1409
Incineration of combustible waste
O2 _ 181 lb/hr
N2 - 1710 lb/hr
CO2 - 322 lb/hr
H20 - 151 lb/hr
SO2 - 1 lb/hr Solids - 5 lb/hr
Total - 2370 lb/hr Temperature - 950°C Pressure — 13.5 psia
CFM - 2407
The dry cyclones 320 are for removing solid material in the gas effluent and typically remove at least 82% of the solids contained therein. The gas effluent enters the cyclones at site 322 proximate the top and tangential to one side of each cyclone to achieve a circular swirling motion in a conventional manner. The solids which are separated from the gas effluent settle towards the bottom of the dry cyclone 320 and are exited therefrom via conduit 324 and are directed to a storage hopper 329 . This hopper can be isolated by valves 325 and 331. When full , the hopper is emptied along conduit 327 into disposable container 326. The application of externally attached vibrator 333 to the outlet of hopper 329 assures efficient discharge of the collected particulate . The solid particles are then solidified by conventional means for subsequent disposal such as by burial .
In the dry cyclones 320 , the swirling motion of the air causes a centrifugal force to act upon the solid particles so that they migrate to the wall . The air velocity is lower close to the wall due to the boundary effect so that the particles slide downward along the wall to the particulate exit 328 . The gas effluent exits upward from the top center of each cyclone 320 via conduit 330 and is thence directed to quench tank 332. The dry cyclones 320 can be constructed of the same types of materials as the incinerator/calciner vessel 30 and cooled in a like manner . Multiple cyclones can be placed in series or parallel thus increasing particle removal efficiency . Off-gas in conduit 330 is communicated to a low side site 334 of the quench tank 332. In quench tank 332, the off-gas is cooled by a liquid spray of scrub solution which is introduced into the quench tank 332 via conduit 336 and spray nozzles (not shown). The off-gas remains cool throughout the remainder of the off-gas clean-up system. In quench tank the gas flows counter, current to the water spray which causes intimate contact between the gas and liquid streams. This causes both cooling of the off-gas and wetting of most of the remaining solid particles in the off-gas. The larger liquid droplets fall to the bottom of quench tank 332 and are returned to a scrub solution tank 338 via conduit 340 taking the wetted solid particles along with them. Smaller liquid droplets are swept upwardly out of the quench tank 332 with the off-gas via conduit 342. The quench tank 332 and scrub solution tank 338 are made of corrosion resistant material.
As mentioned, the off-gas exits the quench tank 332 via conduit 342 and is thence directed to venturi scrubber 344. Scrub solution from conduit 336 is sprayed into the off-gas at or near the throat 346 of the venturi scrubber in a conventional manner. In venturi scrubber 344, it is desirable to achieve saturation and entrainment of water to facilitate wetting of those particles which were not wetted in quench tank 332. The off-gas leaving vessel 30 may contain a great deal of water vapor. Moreover, as the off- gas passes through quench tank 332, water vapor, in addition to entrained water, is added. At the venturi scrubber 344, the off-gas is substantially saturated with water vapor. As the off-gas passes through the venturi throat 346, the pressure drops which in turn causes an. increase in the amount of moisture which the gas can maintain in vapor form. Accordingly, evaporation occurs. As the off-gas enters the divergent section of the venturi scrubber, the velocity decreases and the pressure increases thereby resulting in condensation of water vacor. This condensation in turn causes the existing droplets to become larger along with causing new droplets to form on the unwetted particles which serve as condensation nuclei.
As can be seen, the primary purpose of the quench tank 332 and venturi scrubber 344 is to cool the off-gas and wet as many of the solid particles as possible to facilitate removal. It is easier to remove a liquid droplet than it is to remove a much smaller solid particle. The liquid particles are removed subsequently whether the particles are composed of soluble material which have gone into solution in the droplet or the particles are composed of insoluble material which is retained as a wetted solid within the droplet. In either situation, the solid particle moves with the liquid droplet. The venturi scrubber 344 must be constructed from corrosion resistant materials.
Quench Venturi
Tank Scrubber
Gas flow rate (CFM) 1150-1900 552-1070 Inlet temperature (°C) 285-684 69-72 Outlet temperature (°C) 69-72 54-63 Inlet pressure (psia) 13.4 13.4 Pressure differential (psi) negligible 1.8
Scrub solution flow rate (gpm) 5.5 11
Sizing 4 ' dia x 10' 1.7" x 6.6" throat-maximum
The off-gas containing liquid particles is removed from the venturi scrubber 344 via conduit 352 and introduced into wet cyclone 350 via conduit 352 tangentially near the bottom in the conventional manner. The wet cyclone 350 functions in a manner substantially similar to dry cyclone 320, but removes liquid droplets instead of solid particles. In wet cyclone 350, centrifugal force causes liquid to run down the side of the cyclone to a drain 354 in the bottom thereof. The liquid is then removed from the cyclone via conduit 356 and communicated to scrub solution tank 338. The off-gas is exhausted from the top of the cyclone 350 through conduit 358.
Typical operating parameters for the cyclone 350 include a temperature range of about 54 °C to about 63°C, an inlet pressure of about 11.6 psia, a pressure differential of about 1.8 inches H20 and a gas flow rate of about 4.77 to about 1140 CFM.
From the wet cyclone 350 the off-gas passes through an entrainment separator 359 which removes large water droplets. This unit is conventional and is constructed of a wire pad rough which the off-gas must pass. The wire must be corrosion resistant.
Off-gas removed from the entrainment separator 359 via conduit 361 is communicated to a condenser 360 for cooling the gas effluent. Cooling liquid is introduced and removed through conduits 362 and 364. The condenser can be a shell and tube type heat exchanger, if desired. In the condenser, the liquid particles grow in size to a point wherein a significant amount of the water in the off-gas is removed by gravitational or momentum effects. In a gravitational removal mechanism, the drops are so large that they fall to the bottom of the vessel. On the other hand, in a momentum removal mechanism, the droplets are not large enough to fall out of the off-gas stream but they are large enough so that as the gas changes direction suddenly the droplets impinge upon the wall or other solid material which has caused the direction change. Off-gas leaves the condenser 360 through conduit 366.
Typical operating parameters for the condenser 360 include a gas flow rate of about 480-1180 CFM about 0-8.4 gallons/minute of cooling liquid, inlet temperature of about 54 to 63°C, a temperature differential of about 3-23°C, inlet pressure of about 11.5 psia, and a pressure differential of about 0.5 psi. The off-gas and liquid droplets exiting the condenser 360 via conduit 366 are communicated to a mist eliminator 370. The mist eliminator 370 operates to remove the liquid particles by the momentum removal effect. Off-gas is passed through a filter of woven fibers which causes the gas to undergo rapid and frequent changes in direction. However, since the liquid droplets are too large to turn as sharply as the gas particles, they collide with the filter fibers. The liquid droplets then run down the fiber to the wall of mist eliminator 370 and from there to the bottom drain 372 and conduit 374 which returns the liquid droplets to scrub tank 338.
The off-gas exits the mist eliminator near the top and is conducted through duct 376 into the upper part of the SO2 adsorber tank 377. A bed of caustic impregnated carbon is located within the SO2 adsorber tank 377 and is supported by a horizontal screen! The off-gas flows vertically down through the charcoal. In so doing the SO2 component of the off-gas is removed by the charcoal and adsorbed. Any entrained liquid is removed from the gas and drains through the bed to the bottom of the tank then out drain line 379 to the scrub tank.
The off-gas leaves the SO2 adsorber 377 near the bottom via conduit 381 and is directed to a heater 378 which heats the off-gas to reduce the relative humidity below 100%. This protects the HEPA filter 380 and iodine adsorber 384 from overloading with moisture condensation. The off-gas is conducted from the heater 378 to the HEPA filter 380 via conduit 376 wherein any residual solid particles which were not removed in the mist eliminator 370 are trapped (after residual moisture is evaporated by the heater 378). The filter comprises a medium with very small pores and the particles are removed by impingement. The off -gas exits the HEPA filter 380 via conduit 382 and enters an iodine adsorber 384 which removes iodine by adsorption . The radio iodine atoms are held on the surface of the material until they decay to the stable atom xenon or are removed with the material . An adsorbing agent comprising silver coated silica gel beads or KI impregnated activated carbon may be used .
The temperature of the off-gas through the HEPA filter 380 and iodine adsorber 384 is between about 40 and about 60 °C and the flow rate is between about 540 CFM and about 1180 CFM. Following the iodine adsorber , the off -gas is directed via conduit 386 to a second HEPA filter 388 . The KEPA filters 380 and 388 are commercially available and need not be disclosed in any greater detail herein .
The off-gas leaving the HEPA filter 388 via conduit 390 is sufficiently decontaminated that any amountsor radioactive material which may be present in the gas are well below the levels permitted by the plant operating license and accordingly can then be discharged to the atmosphere by a blower 392 and conduit 394 to the plant stack or a separate and sole use stack. .
The NaOH solution is introduced from tank 397 into the scrub solution tank 338 through valve 399 and conduit 396 . Any pH adjusting materials , such as sodium hydoxide , are added to the scrub solution tank from time to time as needed as aqueous soltuions via conduit 396 . The scrub solution is removed from the scrub tank via conduit 398 and under force of pump 400 . In addition , if desired , a device 402 for removing solid particles can be included in line 398 between scrub tank 338 and pump 400. Scrub liquid is then fed to a heat exchanger 404 wherein it is cooled sufficiently so that a portion of it can be used as the spray in quench tank 332 and venturi scrubber 344 via conduit 336 . Some liquid purge from the scrub tank may be returned to liquid waste tank 192 via conduit 164 . The teiαoerature downstream of the scrub cooler 404 is typically about 30-50 °C . A typical flow rate of the scrub solution to the quench tank 332 and venturi scrubber 344 is about 16. 5 gallons/minute and that of the scrub solution recirculating to the scrub solution tank 338 is about 11 gallons/minute .
Reference is now made to Figures 7-11 which illustrate a presently preferred venturi scrubber 344 according to the present invention . The venturi scrubber 344 is vertically mounted and comprises three primary portions , i . e . an approach or contraction cone , generally designated 420 , a central throat assembly , generally designated 422 , and a re-entry or expansion cone , generally designated 424 .
The approach cone comprises a mounting flange 426 equipped with an array of apertures 428 by which the leading end of the as sembly is secured in the offgas system in the position illustrated in Figure 6 . The flange 426 integrally merges by welding, for example , at site 430 with a tunnel 432 which defines a rectangular inwardly tapered rectangular passage 434 comprising part of the flow path for the off-gas in system 40 . The converging passage 434 is formed by integrally welded plates 436 , 438 , 440 and 442 . The tapered proj ection 432 is welded onto the leading opening 444 of the throat assembly 422 so that the interface between the cone 420 and the throat assembly 422 is air tight and smooth .
The throat assembly 422 comprises a generally rectangular block 446 , a similarly shaped generally retangular block 448 and opposed , substantially identical though opposite hand side blocks 450 . The blocks are secured together as illustrated in Figure 7 preferably by welding . The off-gas passageway 452 (which comprises influent opening 444 and effluent opening 45.4 ) is configurated as best illustrated in Figures 10 and 11. More specifically , the interior surface 456 of the top block 446 is substantially continuous as illustrated in Figures 10 and 11 (see especially Figure 11) . Surface 456 merges with o ffset surface 458 across a perpendi¬ cular shoulder 460 , a recessed face 461 and a second shoulder 463. The stepped surface 458 is flanked on each side by a relatively narrow surface 462 which merges smoothly with surface 454.
The distance between the two spaced exterior surfaces 462 is only slightly greater than the width of a generally planar throat adjustment plate 464. Accordingly, the throat adjustment plate 464, when in its "out" position as illustrated in Figure 11, is entirely disposed within the rectangular space between flanges 462, shoulders 460 and 463 and surfaces 458 and 461. The spaced surfaces 462 each contain an aperture 466, which apertures are aligned one with the other.
In the assembled position a pivot pin 468 fits tightly through the two apertures 466 and fully spans between the spaced flanges 462 and beyond. An exposed pivot pin head 470 retains the pivot pin 468 in the illustrated position at one end, while a nut 472 tightly secured to the threaded end 474 of the pivot pin 468 secures the other end of the pin in the illustrated position. The pin 468 fits loosely through an eyelet 476 of the venturi throat adjustment plate 464 and secures the adjustment plate 464 in pivotable, cantilevered fashion as illustrated in Figure 11. The cantilevered portion of the adjustment plate 464 comprises a linear portion 478 integral with the eyelet 476 and tangentially disposed in respect thereto together with an angularly disposed distal end extension 480. The juncture 482 between the linear portion 478 and the angular portion 480 constitutes a throat-identifying region in the assembly 422.
A threaded bore 484 is centrally disposed in the body 446 and receives a stop bolt 486. The distal end 488 of the stop bolt 486 contiguously engages the outer surface of the venturi adjustment plate portion 478 just upstream of the throat defining portion 482. Lock nut 490 can be loosened an appropriate distance and stop bolt 486 can be adjusted inward to move venturi plate 464. It is presently preferred that the venturi adjustment plate 464 be adjustable through on the order of 36°. Once a desired setting of the bolt stop 486 is obtained, the lock nut 490 is again tightened to retain the selected plate orientation. During each adjustment of the orientation of the plate 464, rotation is accommodated at eye 476 about pivot pin 468, which loosely passes through the eye.
A transverse scrub solution passageway 500 is disposed across the entire width of the block 446. The passageway 500 is threaded at each end 502. One end of passage 502 is plugged with a threaded plug having wrenching surfaces for use during installation and removal. The other end of passage 502 is connected to conduit 336 (Figure 6) for delivery of scrub solution. In addition, four aligned threaded ports 504 smaller than passageway 500 span between the passageway 500 and the outer surface 506 of the body 446. Accordingly, there exist four ports 512 in block 446 which align with ports 504 and penetrate to the inside surface of block 448. These ports form nozzles 512. The ports 504 are plugged, preferably with threaded plugs 509 having an exposed wrench-receiving head for placement and removal purposes.
Scrub solution delivered in any suitable fashion to passageway 500 is caused to be slowly sprayed under moderate pressure through the nozzle openings 512 (disposed in surface 456 directly opposite threaded ports 504) into the off-gas passageway of the throat assembly 422, whereby residual particles contained within the off-gas are wetted and encapsulated within liquid droplets and removed from the off-gas by the wet cyclone.
The interior face of the block 448 comprises a linear surface 520 (disposed beginning at the upstream opening 444 of the off-gas passageway through the throat assembly 422), which merges with a divergently tapered face 522. The divergent face 522 terminates adjacent the effluent opening of the off-gas passage in the throat assembly. The site 524 (at which the surfaces 520 and 522 merge) is disposed opposite the adjustable throat site 482 of the venturi adjustment plate 464. Thus, as the orientation of the plate 464 is altered, the alignment between the throat sites 482 and 522 is substantially maintained, although the distance between the two sites is varied in correspondence with the magnitude of angle change in the reorientation of the plate 464. The divergently tapered surface 522 is flanked on each side by a narrow longitudinally directed surface 526, which is contained within a plane also containing the interior surface 454 of the adjacent side block 450.
The bottom block 448 comprises a centrally disposed vertical threaded bore 528, which receives a second elongated threaded stop bolt 530. The distal end 532 of the bolt contiguously engages the outer surface of the plate portion 478 in alignment with the previously described threaded stop bolt 486. Accordingly, each reorientation of venturi adjustment throat plate 464 will require manipulation of both threaded stop bolts 486 and 530 through loosening of the lock nuts 490 and 532 (as previously described) , threaded advancement or retraction of the threaded bolt stops by tool engagement with heads 492 and 534 to place the plate 464 as desired,, following which the lock nuts 490 and 532 are again tightened.
A transverse scrub solution passageway exists across the full width of the block 448 in alignment with the previously described scrub solution passage 500 in the top block. The block scrub solution passage 550 is identical through the inversion of the previously described passage 500 and is correspondingly numbered. Thus, scrub solution contained under pressure in passageway 550 will be sprayed slowly through the adjacent nozzle opening 512 into the off- gas axial passageway of the throat assembly.
The two identical though opposite hand side blocks 450 are exteriorly rectangular. Thus, when the throat assembly 422 is assembled, all of the exterior threaded port leading to the described scrub solution passageways within the four blocks may be plugged, with the exception of two so that solution under pressure sprays into the throat assembly from opposite sides.
The re-entry cone 424 comprises a mounting flange 560 equipped with an array of apertures 562 by which the trailing end of the assembly is secured in the position illustrated in Figure 6. The flange 560 integrally merges by welding, for example, at site 564 with a tunnel 566 which defines a rectangular outwardly divergent tapered rectangular passage 568 comprising part of the flow path of the off-gas in system 40. The diverging passage 568 is formed by integrally welded plates 570, 572, 574 and 576. The tapered tunnel 566 is welded to the trailing opening of the throat assembly 422 so that the interface between the re-entry cone 424 and the throat assembly 422 is air tight and smooth.
Thus, the manually adjustable venturi scrubber embodiment of Figures 7—11 is available to vary the cross sectional area of the throat of the venturi scrubber 344 to correspondingly vary the pressure drop at the throat. Heretofore, the existence of a fixed venturi scrubber throat has presented problems in removing substantially all radioactive particles from the off-gas. This present adjustment capability, to the contrary, allows the operator of the overall system to optimize, on a custom basis, the condensation obtained at the venturi scrubber 344 which enhances particle removal through wetting and centrifugal action (obtained in wet cyclone 350).
Reference is now made to Figure 12 which illustrates a second presently preferred venturi scrubber embodiment 344'. Venturi scrubber 344 ' is substantially similar to the previously described venturi scrubber 344, except modifications exist to provide for automated and remote control of the orientation of adjustment plate 464. More specifically, the throat assembly 422' comprises block 446', block-448' and blocks 450. The scrub solution passageways and front end portions of the blocks 446', 448' and 450 of the throat assembly 422' are identical to those of throat assembly 422. The block 446' is otherwise identical to block 446, except the previously described threaded bore 484 has been removed and replaced by a smooth bore 590 which is located near the effluent end of the assembly 422' and midway across the width of block 446'. Block 448' is identical to the previously described block 448, except the previously described threaded bore 528 has been eliminated. The blocks 450 are the same.
In addition, a hydraulic, pneumatic or electric actuator assembly, generally designated 592, is superimposed over and in alignment with the smooth block bore 590 and is conventionally secured to the block 446' in any suitable way, e.g. via countersunk screws (not shown) or welded.
The actuator 592 comprises a two-way device 594 from which a piston rod 596 extends. The rod 596 termintes in a clevis 598 which is pivotally attached at pin 600 to a rotatable link 602. Link 602 is in turn pivotally connected by pivot pin 604 to a second clevis 606, the base of which is welded at site 608 to the top surface of the throat adjustment plate 464 near the distal end thereof. Thus, as the angle-of inclination of the throat adjustment plate 464 is increased and decreased by actuation of the operator 594, the pivotable or toggle arrangement described above, which is interposed between the end of the rod 596 and the plate 496 is allowed to correspondingly pivot to avoid binding.
The isolation housing of actuator 592, as illustrated in Figure 12, comprises a block 610, by which the actuator 592 is mounted to the top of the throat assembly 422'. The body 610 comprises a stepped central smooth bore 612, the narrow diameter portion of which comprises a groove 614 in which a sealing O—ring 616 is disposed. The block or body 610 is closed by an end plate 618 held in pos ition by cap screws 620 , which thread into, the body 610 . Thus , the throat cross section and configuration may be varied by appropriately advancing and retracting the piston rod 596 through controlled actuation o f actuator 594 , on a remote basis .
Reference is now made to Figures 13 and 14 which illustrate a presently preferred embodiment of the previously mentioned iodine adsorber 384. Adsorber 384 , as illustrated in Figures 13 and 14 , comprise at each end a mounting flange 640 , each flange 640 having an appropriate shape and apertures 642 by which the adsorber 384 is mounted in the off- gas system in the position illustrated and earlier described in conjunction with Figure 6 . Each flange 64 0 comprises an off-gas opening 644 .
Adjacent to each flange 640 is a generally linear air tight hollow retangular conduit portion 646 , which integrally, by welding or otherwise , merges with an adj acent hollow truncated pyramid section 648 . Each truncated section 648 is fabricated of sheet metal and is air tight and capable of resisting internal and external pressure . Adj acent to each truncated pyramidal section 648 is a generally rectangular hollow sheet metal section 650 , welded or otherwise integrally secured to the adjacent truncated pyramid section 648 . In each rectangular section 650 is mounted a pressure sensing tap 652 , by which the pressure differential across the iodine adsorber 384 is determined on a continuing basis . Each section 650 also includes a removable inspection and access plate 654 , which, when in the assembled position and tightened , is air tight .
Interposed snugly by welding or other means between the two sections 650 is an adsorber section 656 . The adsorber section 656 is serviced by an inlet conduit 658 through which the adsorber bed material is introduced into the adsorber section 656 when the valve 662 is ooened and flows by gravity through the conduit 658 into a central hollow portion within the adsorber section 656. Chamber 660 is a reservoir which insures that adsorber 656 remains full during operation.
In like fashion, spent adsorber bed material is discharged under force of gravity through conduit 664 when valve 666 is opened.
It is to be appreciated that while adsorber section 656 is illustrated in Figure .13 as being constructed and located so as to present surfaces aligned with the surfaces of the section 650, that flanges or other suitable mounting structure could be used so that the adsorber section could be independently inserted and removed from its assembled position in the iodine adsorber 384.
The interior of the adsorber 656 includes fore and aft screen assemblies 670 with a hollow space therebetween. The screen assemblies 670 are intended to be spaced one from the other a predetermined distance to provide the mentioned space to thereby accommodate insertion of the adsorber bed material in the previously mentioned fashion therebetween. Each screen assembly 670 (as best illustrated in Figure 14) comprises a rectangular peripheral frame 672 secured to the exterior metal shell 674 of the adsorber section 656 by welding. The frame 672 has mounted thereto along the entire interior surface in an air tight fashion an endless rectangular rod 676, the corners of which are mitred. A plurality of spaced rods 678 extend between parallel portions of the rod frame 676 in the perpendicular fashion illustrated.
The rods 678 thus form openings 680 therebetween. The openings 680 are illustrated in Figure 14 as being of substantially equal size one in respect to the other. Preferably the crossing rods 678 are welded or otherwise secured to each other at the sites 682 where an overlap occurs. The ends of the crossing rods 678 are also secured as by welding or the like to the rod frame member 676. Thus, the network of rods 676 and 678 form a strong frame against which a rectangular screen , having substantially the same peripheral dimensions as the peripheral rod 676 , is superimposed in such a fashion that the iodine adsorber beads are retained and off-gas flow is required to pass through the screen 684 without short circuiting around the edges o f the frame .
Accordingly , the adsorber bed material is introduced into the adsorber section 656 between the spaced screen 684 with off-gas air being caused, to come into intimate contact with the bed material as the off—gas is displaced through the iodine adsorber 384 . It has been discovered that iodine in the off-gas will be substantially entirely adsorbed if the media or bed material is silica gel coated with silver or activated carbon impregnated with potas sium iodide and an amine . As the bed material in the adsorber section 556 is depleted , it may be removed as previously described and replaced by an additional supply also introduced as described . The bed material replacement can be accomplished remotely by use of remote control, valves and appropriate piping to and from the adsorber bed .
Instrumentation and Control
The instrumentation and control system provides input for control over the process , as well as informing of off- normal conditions and detects conditions that may result in excessive radiation levels exiting the off-gas system. The overall system 28 shown in Figures 2- 6 is equipped with instruments designed to sense and activate alarms upon the occurrence of a wide variety of off-normal operational conditions . A part of the instrumentation and control are annunicators which provide identification of the causes o f any alarm. Corrective action is taken either automatically or manually , depending on the potential seriousness of the abnormal occurrence .
The system 28 also monitors the off-gas system to insure that releases to the atmosphere are well within prescribed limits . The instrumentation and control system provides the operator with information for process control to maintain the system parameter's within safe and efficient limits and also monitors the performance characteristics of certain components . Monitoring the performance of these components allows the operator to anticipate many problems before a system shutdown becomes necessary . For example , the scrub liquid strainer pressure differential is recorded. The operator is able to observe the effects of plugging and take corrective action before a condition such as loss of scrub liquid flow develops .
Another feature which is included in the instrumentation and control system is a two-level alarm and protective action procedure . When a selected parameter drifts outside of the normal operating band , the first indication is an alarm which notifies the operator of the problem. If corrective action is not taken , a second alarm, set slightly further outside the control band is actuated . This second alarm is accompanied by automatic protective action . By using this two-level action , many process problems can be and are corrected by the operator before protective action is initiated and poss ible process shutdown results .
Still another feature of the instrumentation and control system which leads to improved relability is the remote control capability of the system. All equipment can be remotely valved in or out and remotely started . This feature minimizes the operator action away from the control room.
The safe operation of the system is provided by control sequencing which prevents improper operation and effect automatic system shutdown if system parameters are not maintained within the prescribed limits .
The following table identifies the instrumentation shown in Figures I5A , 15B and 16- 26 of the drawings :
Figure imgf000048_0001
Figure imgf000049_0001
More specifically, with reference to Figures 15A-25, there is depicted a presently preferred instrumentation and control system. Each of the components of said system are readily identified by reference to the tables hereof. Each of the identified components is commercially available and, therefore, requires no structural or installation disclosure.
The instrumentation and control for the waste feed system is illustrated in Figures 15A, 16 and 17.
Figure 15A schematically depicts one type of shredder which may be used in conjunction with the present invention wherein a manually controlled motor driven shredder mechanism enclosed within a hopper delivers shredded solid combustible waste as sized piieces to a shredder conveyor. The conveyor is likewise motor driven and manually controlled. Dust generated within the shredder hooper is drawn into a manually controlled motor driven dust collector. The collector delivers solids derived from collected dust to the conveyor. Under certain conditions explained hereinafter in greater detail signals from the interlock system will shut off, in timed sequence, the shredder motor, the dust collector motor and the shredder conveyor motor and isolation valve 167. It is preferred that upon complete shredder shut down, no dust remain in the dust collector and no shredded waste on the shredder conveyor, which might jam the conveyor at. start up.
In respect to Figure 15B, it may readily be observed that the top and bottom internal, temperatures of the solid waste tank 168 are monitored as is the pressure within the bottom of the tank. Excessive temperature at either location indicates combustion within the tank and causes a signal to issue to the instrumentation system and a fire extinguisher to automatically issue water or other fire retarding liquid through a solenoid valve 700 to the tank 168 and the screw conveyor 172. A hand control may be used to achieve the same result manually. All motors may be started and stopped manually using the associated hand control and each is remotely monitored through an instrumentation system, hereinafter explained in greater detail. The rate at which the bottom augers deliver shredded waste from the tank 168 to the screw conveyor 172 is varied up and down according to the mean temperature of the fluidized bed so that the proper amount of waste reaches the vessel for efficient, continuous incineration.
Likewise, all remote operated valves may be manually controlled by the associated hand control and each is remotely monitored through the instrumentation system. The motor for the bottom augers, the screw conveyor motor and the blower motor, respectively, may be remotely shut offthrough the control system, as may isolation valves 170 and 173 and solenoid valve 702. In the event the screw conveyor 172 exhibits excessive temperature, the operator is informed by the issuance of an alarm. If pressures within the solid waste tank 168 become excessively high, an alarm is issued. This is also the case if the air flow rate and/or air pressure within the pneumatic conveyor 108 becomes unacceptably low. Furthermore, if the amount of waste in the tank 168 becomes excessively low or high an alarm issues. The 1
The liquid waste control and instrumentation system as presently preferred, illustrated in Figure 16, specifically monitors and regulates (using the exterior heater) the interior temperature of the liquid waste tank 192, monitors the inlet and outlet pressures of the pump 198 and regulates the rate at which the pump 198 displaces liquid waste into conduit 112. It monitors the pressure differential across the strainer 201, to detect clogging, monitors the flow rate and pressure within liquid waste conduit 112 and monitors and regulates the flow rate of the liquid waste atomizing air in conjunction with the flow rate of liquid waste in conduit 112. The atomizing air is mixed with the liquid waste at or adjacent to the bed 66. The agitator within the tank 192 is operated by a manually controlled motor and the strainer bypass flow control valve 197 is automatically controlled by flow in conduit 203. The motor for strainer 201 is also manually controlled.
The interior temperature of the tank 192 is continuously recorded, and it is regulated by use of the exterior heater, which is controlled by the associated temperature indicator controller. An alarm is issued when and if the tank temperature is unacceptably low. The level of liquid waste in the tank is automatically controlled by a level controller and the flow control valve 698 in conduit 164. Alarms are issued if the tank, level becomes too high or too low. If the level in tank 192 continues to drop below the low level alarm point, the low low alarm point will be reached and a second alarm is sounded. At the second alarm corrective action is automatically initiated to open valve 698 and shut off pump 198. If the high level alarm point is exceeded a second alarm is sounded at a slightly higher level in tank 192 and corrective action is initiated by closing valve 698.
An alarm is caused to issue when the influent pressure to pump 198 is low or the effluent pressure of the pump is high. If no corrective action is taken and the condition worsens, a second alarm issues and the interlock logic stops the motor of pump 198, closes the control valve in conduit 164, and closes the isolation valve 199 and the isolation valve 708 downstream of pump 198 within conduit 112.
Alarms (without interrelation with the interlock logic) are caused when the tank temperature becomes excessively low, when the pressure differential is high across the strainer of valve 201, when the pressure is high in conduit 112 on either side of the isolation valve 708 located downstream of pump 198 and when the flow rate of atomizing air in conduit 115 is low. In addition to the foregoing, the rate of liquid displacement caused by pump 198 is stopped at the occurrence of any one of four events, i.e. (a) low pressure at the influent to pump 198, (b) high pressure at the effluent of pump 198, (c) inadequate flow at the flow element contained within conduit 112, and (d) an inadequate flow rate of the air within conduit 115 used to atomize the liquid waste.
It is preferred upon closure of isolation valve 199 that heated water displaced across isolation valve 706 be used to purge waste from conduits 112 and 203 for a limited time.
Figure 17 illustrates the presently preferred instrumentation and control system applicable to the resin and sludge waste feed. From Figure 17, it is apparent that all valves may be manually and remotely controlled. Further, the interlock system provides for the selective and independent control of isolation valve 184, the isolation valve 187 at the effluent of the dewatering tank 186, the isolation valve 718 in conduit 194, the isolation valve 716 in the loop conduit which spans between feed pump 188 and dewatering pump 196, the isolation valve 711 disposed downstream of pump 188 the isolation valve 710 contained in conduit 110 and the isolation valve 717 which controls the input of kaolin clay from tank 719 along conduit 721.
The interlock system may signal closure of the valve 187 disposed at the effluent of tank 186, the isolation valve 718 disposed in conduit 194 and the isolation valve 716 disposed in the mentioned feed pump—dewatering pump conduit, and the isolation valve 711 downstream of pump 188.
The interlock logic monitors the motor rotation of the agitator of tank 186 and controls the starting and stopping of pumps 188 and 196. The rate of the pump 188 is adjustable to control flow of material into the fluidized bed. The air flow within conduit 110 is monitored continuously and the two level, alarm approach previously mentioned is utilized. More specifically, when the air flow, rate drops below the desired value, an annunciator is sounded to prompt corrective action by the operator. If corrective action is not taken by the operator and air flow drops further, a second alarm is caused to issue and the control system shuts down the mentioned components associated with the resin and sludge waste feed. The interlock system regulates air flow at the solenoid valve in conduit 110. The pressure within conduit 110 is communicated to the operator by a pressure indicator.
The level of waste in the dewatering tank 186 is monitored and valve 184 controlled to correct highs and lows.
Upon shutdown, demineralized water is used to purge residual waste from the conduit 194 , and the conduit downstream of the pump 188.
Figure 18 depicts presently preferred controls and instrumentation for the fluidized bed vessel. Specifically, the temperature of the effluent off-gas in conduit 100 is monitored and recorded. Similarly, the pressure differential across the depth of the bed is monitored and recorded. The isolation valve 141 at the bottom of the vessel 30 is remotely manually or automatically controlled to regulate the removal of used bed material from the vessel, while the flow control valve 132 at the cooling air effluent may be subjected to remote manual or automatic control to insure adequate cooling thereby maintaining the temperature of the inner shell 50 at about or below 1200°F.
The pressure at the top of the vapor space 64 is monitored and used to regulate the amount of ambient air added at the off-gas blower inlet and thereby regulate the vapor space pressure. When the indicated pressure is high, an alarm is issued to the operator. The temperature is monitored at three separately spaced sites within the vapor space 64 of the vessel 30. Each temperature is recorded. In the event that any two of the three sites monitored indicate an unacceptably high temperature, an alarm is issued. Two out of three sensors are required to read a high temperature to initiate an alarm or shutdown. In this way, malfunctioning of any one temperature sensor does not effect protective action. If for some reason the corrective action taken by the automatic temperature control system (or by the operator) is ineffective and the temperature continues to rise, when a predetermined high temperature is reached a second alarm issues and the control system initiates shutdown of the process.
The temperature of the bed 66 within the vessel 30 is likewise monitored at three separate sites. The continuous temperature at each site is recorded. If any two of the three monitoring sites indicate an unacceptably high bed temperature, initial alarm is sounded. Two out of three sensors are required to read a high temperature to initiate an alarm or shutdown. In this way, malfunctioning of any one temperature sensor does not effect protective action. If, for some reason, the corrective action is not taken and the temperature continues to rise, when a predetermined high temperature is reached, a second alarm is issued and the control system shuts off the fuel oil and waste feed systems. The same two level concept is used for the two low temperature alarms and the two low temperature protective actions in the event the bed temperature at two or more of the mentioned sites falls below an acceptable temperature.
Furthermore, a temperature indicator controller senses the mean temperature of the bed and causes the magnitude of heat generated by preheat burner 124 (Figure 19) to be appropriately adjusted up or down by regulating the magnitude of fuel supplied from fuel source 150 to the heater 124. All sensors exposed within the interior of the bed are formed of material which will withstand the high temperature and corrosive atmosphere.
Reference is now made to Figure 19 which illustrates presently preferred instrumentation and controls for the fluidizing air preheat burner 124 , as currently preferred . The motor powering blower 126 may be manually started and stopped and is also stopped by the control system. Both the fluidizing air blower 126 and the shutoff solenoid valve 720 located within the liquid fuel line 104 are controlled manually by the operator or by command signals from the control system. Also , as mentioned earlier , the flow control valve disposed within the liquid fuel line 104 is regulatedby the bed temperature sensing circuit previously described . The pressure and temperature within the conduit 122 are monitored by pressure and temperature indicators .
In addition , the pressure within the conduit delivering atomizing air to the preheat burner 124 is continuously monitored and , if unacceptably low, an alarm is issued to the operator .
The temperature of the burner fluidizing air effluent is monitored and recorded or displayed on an indicator , depending upon the setting of the associated selector switch . If the effluent temperature of the burner 124 is unacceptably high, an alarm is issued to the operator . The flow of the three branches of conduit 122 (supplying cooling , combustion and overfire air) is monitored .
The combustion and cooling flow within said conduit 122 is recorded and is used as a basis for regulating the low control valve disposed downstream in the cooling air conduit. If the flow rate is unacceptably low, an initial alarm is issued. If the related flow control valve (or the operator) does not cause corrective acton to be taken and the flow rate continues to drop , corrective action is taken automatically by the control system to avoid damage or excursion of system paramters outside acceptable levels . The flow in overfire air conduit 102 is monitored and recorded. The results of the monitoring are used to continuously regulate the flow control valve 137. If such flow control valve regulation fails, and the flow rate in conduit 102 becomes unacceptably low, the operator is informed by the issuance of an alarm.
A flow rate monitoring and control system is provided for the fuel, combustion air and atomizing air flow rates. The atomizing air and combustion air are supplied to the burner at rates which are proportional to the fuel flow.
The fuel and the atomizing air flow rates are continuously recorded.
At start up it is preferred that propane or like fuel from a pilot fuel tank be communicated to the burner chamber across a solenoid valve 722, which in turn is controlled by the control system. After the propane pilot light has burned in the chamber for a short period of time, the liquid fuel from conduit 104 is introduced into the burner chamber. The supply of propane is terminated once the main flame is proved. The burner flame in the burner chamber is continuously monitored.
Reference is now made to Figures 2024 which illustrate presently preferred instrumentation and control for the off- gas system. More specifically, the temperature of the off- gas effluent from the dry cyclones 320 are monitored at conduit 330, and recorded or visually displayed depending upon the setting of the associated selector switch. The isolation valves 325 and 331 are remotely controlled in such a way that when one set is open the others are closed. Accordingly, solid particles may be delivered to product pots 329 across either valve 325 and contained therein until product pot 329 is full at which time they are placed in container 326 across valves 331, valves 325 being closed during the interval of time required to dispense solid particles to container 326. A vibrator 333 is associated with each pot 329 to aid in discharging solid particles therefrom. Each dry cyclone 320 comprises an annular air space through which cooling air is caused to pass. The magnitude of cooling air so displaced is regulated by interconnected remotely controlled flow control, valves in the cooling air effluent conduits of the dry cyclones 320.
The temperature within the off-gas effluent conduit 342 from quench tank 332 (Figure 21) is monitored and either recorded or visually displayed to the operator depending upon the setting of the associated selector switch. An unacceptably high temperature causes an initial alarm and, if no corrective action is taken by the operator and the temperature continues to increase, a second alarm is issued and corrective action is automatically initiated. The abnormally high temperature condition causes the addition of demineralized water to conduit 336 through valve 734. This is introduced into the quench tank 332 to reduce the temperature thereof. Zn addition, the mentioned valve may be manually controlled by the operator.
The pressure within the scrub solution conduit 336 is continuously monitored and visually indicated to the operator- An unacceptably low pressure causes an alarm to issue to the operator.
In addition, the flow rate within the scrub solution conduit 336 is continuously monitored and recorded. The results of the monitoring are used to regulate the flow control valve in conduit 336 so that appropriate adjustments occur to maintain the desired rate of flow. If abnormally low flow rates occur, an alarm is also issued to the operator. Demineralized water is used across solenoid valve 734 to replace scrub liquid in conduit 336 and tank 332 if flow of scrub liquid fails.
Preferably, an isolation valve 732 is disposed in scrub solution return line 340 and is remotely operated automatically by the control system or manually by the operator to control the level of liquid in the tank 332. Figure 22 illustrates instrumentation and controls presently preferred for the venturi scrubber 344 and the wet cyclone 350 . The pressure differential across the venturi influent conduit 342 and the wet cyclone effluent conduit 358 is continuously monitored and recorded . If the indicated pressure differential is abnormally low , the operator is informed by the issuance of an alarm.
The throat 346 of the venturi scrubber 344 is variable , as previously mentioned , and is preferably set from time to time by an associated remote manually controlled motor .
The pressure within the scrub solution influent conduit 336 is continuously monitored and the operator is visually informed hereof . If the pressure within conduit 336 falls below an acceptable level , the operator is informed by the issuance of an alarm.
In addition , the flow rat.e of scrub solution within conduit 336 is continuously monitored and may be recorded if selected by the selector switch. This continuous flow rate information is used to regulate the flow control valve contained within conduit 336 . A two level alarm system is provided . An initial alarm issues if the flow rate within conduit 336 is unacceptably low . If no adequate operator correction or feedback correction occurs and the flow rate continues to drop a second alarm is issued and the control system causes corrective action to be taken by initiating demineralized water addition through solenoid valve 736 . A manual override is provided for controlling the flow control valve disposed in conduit 336 . Upon termination in the flow of scrub liquid , a solenoid valve 736 is caused to be opened by an interlock control solenoid and demineralized water is caused to replace scrub liquid in conduit 336 and scrubber 344 .
As illustrated in Figure 23 , the pressure differential across the entrainment separator 359 is continuously monitored and the results thereof visually indicated to the operator. An abnormally high pressure differential is brought to the attention of the operator by the issuance of an alarm.
The temperature at the influent conduit 358 to the entrainment separator 359 is continuously monitored and either , recorded or visually displayed for the operator , depending upon the setting of the associated selector switch .
The temperature of the off-gas effluent in conduit 366 issuing from condenser 360 is continuously monitored and recorded. In addition, the indicated temperature information is used to regulate the temperature control valve disposed in the cooling water effluent conduit 364 , which will alter the cooling effect occuring in condenser 360 to produce an off-gas effluent therefrom having an acceptable temperature .
The off-gas pressure differential across the mist eliminator 370 between conduits 366 and 376 is continuously monitored and the results visually displayed for the operator. An unacceptably high pressure differential causes an alarm to issue to the operator .
The pressure of the effluent off-gas issuing from mist eliminator 370 in conduit 376 is continuously monitored and recorded.
Water is manually caused to flow across related solenoid controlled valves to purge the entrainment separator and mist eliminator at those points in time when off-gas flow therethrough is terminated.
With reference to Figure 24 , the SO2 adsorber bed temperature is continuously monitored with visual display and recording if the selector switch is so positioned . The pressure differential across this bed is continuously monitored and displayed for the operator . If the pressure becomes unacceptably high an alarm is issued .
The off-gas flow rate in conduit 377 downstream of SO2 adsorber tank 379 and in advance of heater 378 and the temperature at the effluent of the heater 378 are continuously monitored. The operator is informed of any unacceptably low flow rate by the issuance of an alarm and operator or interlock corrective action is initiated . The indicated temperature is continuously recorded. If the temperature at the effluent of heater 378 becomes unacceptably high , an initial alarm is issued. If no operator correction takes place, and the temperature continues to rise , a second alarm follows and the existence of abnormality is sensed, by the control system which automatically causes an appropriate reduction in the heat generated by the heating element within the heater 378 by shutting it off . A manually controlled valve accommodates drain of accumulated water within the heater 378 .
The pressure across each HEPA filter 380 and 388 is continuously monitored and the results visually displayed for the system operator . Any abnormally high pressure differential , indicating a partial clogging of the filter is brought to the attention of the operator by the issuaance of an alarm. The pressure differential across the iodine adsorber 384 is likewise monitored with alarm capability .
The moisture content within the off-gas displaced through conduit 382 is continuously monitored and visually displayed for the system operator. Any abnormally high moisture content is brought to the attention of the operator by the issuance of an alarm.
The aforementioned iodine adsorbent is selectively communicated to the iodine adsorber across a control valve . Likewise the iodine adsorber may be manually drained . Temperature of the adsorber is continuously displayed for the operator .
With continued reference to Figure 24 , the motor driving the off-gas blower 392 may be controlled and regulated either manually or by signals received from the interlock logic .
A pressure control valve regulates the magnitude of ambient air added to conduit 394 at the blower 392. This ambient air addition is controlled by pressure sensed at the top of the bed vessel 30, as previously described.
The flow rate in conduit 394 is continuously, monitored and recorded. If an unacceptably low flow rate occurs, an alarm is issued and protective action is taken. The remaining motors of the off-gas system cannot be started in this condition. To insure reliability, a second alarm issues if the flow rate continues to drop and interlock logic corrective action is once more initiated.
Preferably, the conduit 394 is provided with a sample tap for periodic analysis, of the off-gas.
Also, the radioactive level of the off-gas in conduit 394 is continuously monitored and recorded. The operator is informed of any unacceptably high radioactive levels by the issuance of an alarm and if corrective action is not taken by the operator and the radioactivity level continues to increase, the control system takes corrective action. Specifically, the entire system is shut down.
Reference is now made to Figure 25 which illustrates further instrumentation and controls, presently preferred for use in conjunction with the scrub solution system. The pH of the scrub solution returned to the solution tank 338 by conduit 337 is continually monitored and used as a basis to control the flow rate of new scrub additive solution introduced into the tank 338 through conduit 396. More specifically, the information obtained with the pH monitoring is used to not only control the flow rate by regulating the solenoid valve 726 contained within conduit 396 but to control the rate at which the motor driven pump 728 in conduit 396 is caused to displace new solution to the tank -338. If the pH of the return scrub solution in conduit 337 is outside the acceptable range, the operator is informed by the issuance of an alarm.
The temperature within the tank 338 is continuously monitored and, alternatively, either recorded or visually displayed for the operator. The level of the contents within the tank 338 is continuously monitored and the results visually displayed. If the level is high or low, an alarm issues for the operator to initiate corrective action. If adequate correction does not occur and the level continues to drop, a second alarm issues and the interlock system causes corrective action to be taken. The tank may be manually drained across a drain control valve.
The pressure at the effluent of tank 338 in conduit 398 is continually monitored and the results visually displayed for the operator. In addition, the pressure differential across the strainer 402. is continuously monitored. The result is visually displayed for the operator and in the event' the pressure differential is unacceptably high, the operator is informed by the issuance of an alarm. The strainer 402 is preferably a motor driven strainer, which motor is manually controlled for self cleaning.
The motor driving pump 400 may be either controlled manually or automatically by the control system.
The flow control valve in conduit 164 may be regulated so as to continuously deliver a predetermined amount of scrub solution to the liquid waste tank for processing as waste in the manner herein described, thereby preventing excessive accumulation of undesired constituents within the scrub solution.
The temperature at the influent of the quench tank in conduit 336 is continually monitored and the results recorded. The results are also used to continuously regulate a temperature control valve disposed in the cooling water conduit servicing the heat exchanger 404. In this way any excessive temperature is immediately reduced.
The pressure of the scrub solution delivered to the quench tank and venturi scrubber is continuously monitored in line 337. If unacceptably low, the operator is informed by the issuance of an alarm. The results thereof are utilized to continually correspondingly regulate the pressure control valve disposed in conduit 337.
When the flow from tank 338 is terminated, demineralized water is manually caused to purge residual scrub liquid from the conduits downstream of the tank 338.
The Interlock Logic
Reference is now made generally to Figures 2740 which illustrate a presently preferred interlock logic system used in conjunction with the instrumentation and controls heretofore described. The logic is conventionally supplied with electrical power and the logic components appearing in Figures 28-40 are commercially available and their respective operations are outlined in Figure 27. The events describedin respect to Figures 15-26, trigger or in part cause the logic to function as hereinafter explained.
It is to be appreciated that more or less than the annunicators and/or light indicators shown in the drawings may be utilized as desired. Whether shown or not, it is desirable to use annunicators in the present system to signal the following events:
Vessel Bed Temperature High Bed Temperature High High Bed Temperature Low Bed Temperature Low Low Vapor Space Temperature High Vapor Space Temperature High High Vessel Pressure High Solid Waste Feed Dust Collector Off Feed Conveyor Off Feed Conveyor Temperature High Fire Extinguisher On Live Bottom Augers Off Shredder Conveyor Off Shredder Off Vertical Auger Off Injection Air Flow Low Bin Level Low Bin Level High Injection Air Pressure Low Bin Pressure High
Resin Feed Feed Pump Off Agitator Off Injection Air Flow Low Injection Air Flow Low Low
Liquid Waste Feed Feed Pump Off Tank Level Low Tank Level Low Low Tank Level High Tank Level High High Tank Temperature Low Recycle Flow Low Nozzle Air Flow Low
Strainer Differential Pressure High Feed Pump Inlet Pressure Low Feed Pump Inlet Pressure Low Low Feed Pump Outlet Pressure High Feed Pump Outlet Presure High High Liquid Waste Nozzle Pressure High Off-Gas System Off-Gas Flow Low Off-Gas Flow Low Low Dry Cyclone Discharge Valve Closed Product Pot Level High Quench Tank Scrub Liquid Flow Low Quench Tank Scrub Liquid Flow Low Low Venturi Scrub Liquid Flow Low Venturi Scrub Liquid Flow Low Low Mist. El. Differential Pressure High Moisture Level High Radiation Level High Radiation Level High High Heater Temperature High Heater Temperature High High
Entrainment Separator Differential Pressure High S02 Adsorber Differential Pressure High HEPA Filter Differential Pressure High Iodine Adsorber Differential Pressure High Venturi Differential Pressure Low Quench Tank Scrub Liquid Pressure Low Venturi Scrub Liquid Pressure Low Quench Tank Off-Gas Temperature High Qunech Tank Off-Gas Temperature High High
Pre-Heat Burner Burner Off
Atomizing Air Pressure Low Fuel Filter Differential Pressure High Fluidizing Air Flow Low Fluidizing Air Flow Low Low Overfire Air Flow Low Fluidizing Air Temperature High Scrub Liquid Venturi DW Valve Open Scrub Liquid Tank Level Low Scrub Liquid Tank Level Low Low Scrub Liquid Tank Level High Scrub Liquid Tank Level High High
Scrub Liquid Strainer Differential Pressure High pH Level Low
Scrub Liquid Pressure Low Scrub Liquid Additive Tank Level Low
The subscripts used in conjunction with the logic gates or valves shown in Figures 28-40 have the following meanings: FA-fails as is; FC-fails closed; and FO-fails open.
Since the mentioned and illustrated annunicators and light indicators function in a fashion which is readily apparent from an inspection of the tabular information of Figure 27 and the logic depicted in Figures 28-40, no further explanation of these two items is necessary and none will be made.
In respect to Figures 28, 28A and 28B, a fire extinguishing function is automatically caused to occur when an unacceptably high temperature at the top and/or bottom of the bin 168 has been sensed. The fire extinguisher valve 700 is then automatically opened and a fire extinguishing substance is introduced into the bin 168 and into the housing of the screw conveyor 172. The extinguisher manual reset button closes the valve and resets the controls for future operation.
In order for solid waste to be fed to the fluidized bed vessel 30, it is necessary that the feed screw conveyor 172 be operating. For feed conveyor 172 to operate, it is necessary that the bin inlet isolation valve 167 be closed and that the bed temperature be within it's operating range (not high or low). Fluidizing air flow must not be low. The manual start solid waste feed button and solid waste mode select button must each be actuated. Also, the temperature within the bin 168 (top and bottom) must not be high. The bin temperature manual override button must be activated if top or bottom bin temperature is high. Once the foregoing requirements have been met, isolation valve 170 is automatically opened and the screw conveyor 172 begins to rotate to deliver shredded solid waste to pneumatic conveyor 108, provided the screw conveyor power is on, the solenoid valve 702 in conduit 108 is open and the blower 174 is on. Valve 702 is open when valve 170 is open and the pressure within the bin 168 is not high.
It is apparent from observation of Figures 28A that a time delay in the closing of valve 170 and the shutting off of the screw conveyor 172 and the valve 170 (adequate to free the conveyor 172 of any residual waste) is caused to occur when the conveyor 172 is shut off for any of the following reasons: high bin temperature, change in the position of the mode select switch away from solid waste feeding positions, the high high or low low bed temperature, low low fluidizing air flow, actuation of the stop feed button, high high vessel vapor temperature, or high high quench tank off—gas temperature. Conveyor 172 stops after time delay if blower 174 stops. Feed from the solid waste bin into conveyor 172 stops immediately, thus allowing the conveyor to run itself empty.
The valve 702 in conduit 108 closes if the pressure in the solid waste bin 168 is high and if the valve 170 closes.
The vertical auger within the tank 168 is caused to rotate when the auger power is on, the manual local stop and lock out button has not been actuated, and the screw conveyor 172 and/or the shredder conveyor are on.
The live bottom augers rotate at a controllable rate and solid waste is fed to the screw conveyor 172 when the live bottom auger power is on, the vertical auger is turning, the feed screw conveyor 172 is operating and the bottom auger stop and lock out botton has not been actuated.
Rotation of the live buttom augers automatically terminates without delay if the live bottom auger local stop and lockout control is actuated, the conveyor 172 stops or any of the previously mentioned conditions for closing valve 170 occur.
When the shredder conveyor is on, valve 167 is automatically caused to be open. Valve 167 is also automatically opened when all of the following conditions exist: valve 170 is closed, the temperature of bin 168 is satisfactory, the shredder start button has been actuated and the level of solid waste in the solid waste hopper 168 is not high.
For the shredder conveyor to operate it is necessary that: electrical power to the shredder conveyor be provided, that the shredder conveyor local stop and lockout button not be actuated, valve 167 be open, all of the conditions for valve 167 to be open exist, the content of tank 168 not be high, the temperature of the shredder bin (top and bottom) not be high, that the stop shredder hand control not be actuated and the shredder local stop and lockout control not be actuated.
When the valve 167 closes, the shredder conveyor immediately shuts off. The shredder conveyor also stops without delay when the shredder conveyor local stop and lockout control is actuated. The shredder conveyor stops on a delayed basis when the temperature of the solid waste bin (top or bottom) becomes high, the stop shredder control is actuated or the shredder local stop and lockout control is actuated, or the contents of the tank 168 becomes high. The delay allows the shredder conveyor to discharge all shredded waste thereon.
Shredding occurs only when: shredder power is on, the shredder door is closed, the vertical auger in the tank 168 is on, the shredder conveyor is on and the dust collector is on.
Shredding stops if any of the following conditions occur: discontinuation of operation of the dust collector or the shredder conveyor, the shredder door is not closed, the contents of tank 168 becomes high, the stop shredder control is actuated or the shredder local stop and lockout control is actuated.
The dust collector operates only when the dust collector power is on, the dust collector local stop and lockout button has not been actuated and the shredder conveyor is on.
Reference is now made to Figures 29, 29A and 29B which illustrate the presently preferred liquid waste feed interlock logic.
The liquid waste vessel delivery system previously described in conjunction with Figures 3, 4 and 16 utilizes one or more nozzles 114 at all times. In some cases it is desirable to have a vessel with two nozzle capacity wherein either one or both vessel nozzles 114 may be utilized at any point in time. Such a system is illustrated in Figures 29, 29A and 29B and presumes to independent channels for delivering liquid waste each having a pump, a feedback loop, a strainer and related valves, etc. as previously described. The remaining features of each channel of the dual channel liquid waste delivery system of Figures 29, 29A and 29B will become readily apparent from the following description.
A hand operated nozzle selector switch 704 is provided whereby liquid waste may be caused to be delivered to nozzle #1, nozzle #2 or both. Since the steps of operation are identical for each channel or nozzle, only the steps in conjunction with the operation of nozzle #1, will be described, it being understood that the operation of nozzle #2 and nozzles #1 and #2 concurrently occur in the same fashion as described, once the nozzle select switch 704 is properly set. For liquid waste to be fed into the vessel through the selected nozzle 114, it is necessary inter alia, that the associate speed controlled feed pump 198 be operating and that the related isolation valve 199 be open.
Valve 199 is automatically opened when the nozzle select dial 704 has been set, the mode select actuator has been set in the liqud waste position, the preheat burner 124 is on, the start liquid waste feed control has been manually actuated, the contents of the liquid waste tank 192 are not low or low low, the fluidizing air flow is not low, the vessel bed temperature is not low, low low or high, and the stop liquid waste feed control has not been actuated. Furthermore, the pump influent pressure low low and/or the pump effluent pressure high high conditions cannot exist if valve 199 is to open.
Isolation valve 199 closes at once on feed pump inlet pressure low low, feed pump outlet pressure high high, preheat burner not on, liquid waste mode not selected, bed temperature low low, day tank level low low, liquid waste feed stop hand control or nozzle not selected.
Closing of Valve 199 causes, on a time delay basis, termination of the operation of pump 198, and opens the isolation valve to the heated water causing conduit 112 to be purged for a predetermined interval of time, after which the heated water isolation valve 706 is automatically closed. The valve may also be manually closed by actuation of the stop heated water flush manual control. Pump 198 continues to operate, on a time delay basis during the heated water flush cycle. Alternatively, the heated water flush may be achieved by manual actuation of the start heated water flush control.
For normal operation of feed pump 198 it is not only necessary that valve 199 be open but further that any of the mentioned conditions for closing valve 199 not exist, that electrical power be supplied to the pump, that the pump local stop and lockout control not be actuated, that the influent pressure of the pump not be low low, and that the effluent pressure of the pump not be high high.
In order for liquid waste to be dispensed from the operating nozzle 114 into the fluidized bed, it is not only necessary that the associated pump 198 be operating but further that the isolation valve 708 in conduit 112 downstream of the strainer 201 be manually opened.
Closure of the isolation valve 708 in conduit 112 downstream of strainer 201 or stoppage of. pump 198 will terminate delivery of liquid waste to the nozzle 114.
When the pump 198 is operating, the strainer 201 is caused at predetermined time intervals to be wiped to prevent clogging.
Reference is now made to Figures 30, 30A and 30B which depict the presently preferred interlock logic for the resin-sludge feed system.
For delivery of resin and sludge waste to the fluidized bed for incineration, it is necessary that the associated isolation valve 187 be open and the variable speed motor driven feed pump 188 be operating. For pump 188 to operate, electrical power must be supplied to the pump, the solenoid valve 710 in the pneumatic conduit 110 must be open and the air flow in conduit 110 caused by blower 189 must not be low low.
The feed pump 188 is disabled (and resins-sludge feeding discontinued) if air flow in the conduit 110 becomes low low, or (on a time delay basis) if the bed temperaturebecomes low low, the stop feed control is actuated, the local lockout control is actuated, the agitator in the tank 186 is shut off, the contents of the resin feed tank 180 become low, or the preheater burner 124 is shut off. Any of the mentioned time delay conditions also will cause valve 187 to close.
Operation of the pump 188 also requires that the isolation valve 711 adjacent pump 188 be open. The isolation valve 711 is caused to be opened when the mode select switch is set to the resin-sludge feed position, the bed temperature is not high or low, the fluidizing air flow is not low, the start feed button has been actuated, the agitator in tank 186 is operating, the contents of the resin feed tank 186 are not low and the preheat burner is on.
The isolation valve 711 is closed by any of the above mentioned events which cause the pump 188 to stop on a time delay basis and by a low low air flow in conduit 110.
Resin and sludge waste is transferred from tank 180 to tank 186 when the contents of the resin feed (dewatering) tank 186 are not high, the isolation valve 184 is caused to be open, the open fill valve control has been actuated and the agitator in tank 186 is rotating. Agitator rotation Occurs after the agitator start control has been actuated and electrical power is supplied to the agitator.
The agitator is stopped when either the stop agitator control is actuated or the agitator local stop lockout control is actuated.
Isolation valve 184 is caused to close when the close fill valve control has been manually actuated or when the content in tank 186 has become high.
Dewatering occurs in conduit 194 when the dewatering pump 196 is operating, which requires that agitator in tank
186 be rotating, that electrical power be supplied to the pump 196 and that the local stop and lockout control for pump 196 not have been actuated.
Operation of the dewatering pump 196 is terminated if the agitator in tank 186 stops rotating, power to the pump
196 is no longer supplied or the pump local stop and lockout control is actuated.
Dewatering may occur either during resin feeding to the vessel with isolation valve 187 open or when resin feeding is not occuring with isolation valve 187 closed. During resin feeding with the pump 188 and 196 operating, the isolation valve 716 in the conduit loop between pump 188 and conduit 194 is caused to be open and isolation valve 718 closed whereby dewatering occurs through the mentioned conduit loop to the pump 196. When resin feeding is not occuring and, accordingly, isolation valve 187 is closed, the isolation valve 718 in conduit 194 is caused to be open with the pump 196 operating so that dewatering occurs directly through conduit 194. In either case, dewatering terminates when pump 196 is stopped, which causes valves 716 and 718 to close.
Reference is now made to Figure 31 which illustrates the presently preferred preheat burner interlock logic.
For the burner 124 to operate (after the start-up phase), solenoid valve 720 in conduit 104 must be open, a flame must exist in the burner and the pilot fuel solenoid valve 722 must be closed. The normal operation of the burner is terminated when any of the above-mentioned conditions cease to exist.
The solenoid valve 720 in conduit 104 is opened when the fuel pump is on. The fuel pump is on when a flame or pilot light is detected by the flame sensor, electrical power is being supplied to the fuel pump and none of the following conditions exist: the vessel vapor temperature is not high high (on the previously described two of three basis), the bed temperature is not high high (on the preveiously described two of three basis), the fluidizing air flow is not low low, the quench tank off-gas temperature is not high high, the venturi scrub liquid flow is not low low, the burner stop control has not been actuated and the pump local stop and lockout control has not been actuated. If any of the described conditions change, the fuel pump is turned off, the solenoid valve 720 in conduit 104 is closed and combustion within the burner 124 stops.
Burner start-up requires that the burner start control be manually actuated, and that the venturi scrub flow not be low, the quench tank scrub flow not be low, the fluidizing air flow not. be low, the bed temperature not high (on a two of three basis) and the vessel vapor temperature not high (on a two of three basis). Then, burner start is delayed for a two minute interval of time while an air purge occurs thorugh conduits 102 and 122 as well as the burner itself. Thereafter, the burner pilot ignites and propane or the like is automatically caused to oxidize within the burner 124 for an interval of 12 seconds. At the end of a two minute 12 second delay, the interlock causes the solenoid valve 720 to open, the fuel pump to operate and valve 722 to close whereby normal burner operation occurs.
Reference is now specifically made to Figure 32 which illustrates the presently preferred fluidizing air blower126 interlock logic. For combustion air to be delivered through conduit 122 to the burner 124, the motor driven fluidizing blower 126 must be operating. This operation occurs only when the following conditions exist: electrical power is being supplied to the blower, the stack off-gas flow rate is not low and the fluidizing air blower start control has been actuated.
The fluidizing blower 126 is stopped if the hand control blower local stop and lockout control is actuated, the stack gas flow rate becomes low low or the fluidizing air blower stop control is actuated.
Figure 33 illustrates the presently preferred interlock logic for the dry cyclones. Th product pots or containers 329 receive solid particles separated from the off-gas in the two dry cyclones 320 when the cyclone discharge valves 325 are opened. This occurs when the hand control for opening the valves 325 is actuated and both cyclone discharge valves are opened and both solid effluent isolation valves 331 are closed. Actuation of the manual control closes the valves 325, which terminates discharge into product pot 329 . The discharge valves 331 are caused to be open when the valves 325 are closed. The valves 325 are closed manually when the hand control is appropriately actuated. Although not shown, it is preferred that a vibrator be utilized in conjunction with the hopper 329 on those occasions when discharge valves 331 are open.
From the interlock logic depicted in Figure 34 it is apparent that the off-gas reheater 378, which is temperature controlled, is caused to operate only when the heater temperature is not high high, the heater off-gas flow rate is not low and electrical power is being supplied to the heater. The heater is shut off when and if the flow therethrough is low or the temperature thereof is high high.
In reference to the interlock logic of Figure 35, off- gas flow is caused to occur through blower 392 when electric power is supplied to the motor thereof, the start control is actuated and the scrub liquid flow in either the venturi scrubber or the quench tank is not low.
The blower operation is terminated if the scrub liquid flow in either the quench tank or the venturi scrubber becomes low low, the stop blower control is actuated, the blower local stop and lockout control is actuated or the radiation level of the off-gas to the stack is high high and the diverter valve 724 in conduit 394 has been actuated to deliver the off-gas to the stack. The blower shuts off due to excessive radiation in the off-gas.
The presently preferred interlock logic for the scrub liquid system is illustrated in Figure 36 to which reference is now made. For scrub liquid to flow from the tank 338 through the conduit 398, the pump 400 must be operating. Operation of the pump 400 and the presence of electrical power at the strainer 402 cause a cyclic timer to periodically turn the wiper of the strainer to alleviate clogging.
The pump 400 is caused to operate only if electrical power is delivered to the pump, the start scrub pump hand control has been actuated and the scrub liquid level in the tank 338 is not low. The pump 400 is stopped if any of the following events occur: actuation of the pump local stop and lockout control, actuation of the stop scrub pump control, .the level of liquid in the tank 338 becomes low low or the level of scrub liquid in the quench tank becomes high high.
Scrub additive is added to the scrub tank 338 from a suitable source, e.g. a tank, through conduit 396 only when the solenoid valve 726 in conduit 396 is opened. The solenoid valve 726 is caused to be open only when power is being supplied to the adjacent pump 728, the scrub liquid pump 400 is being operated, the scrub liquid being returned to the tank 338 through the conduit 337 has a low pH and there is an ample supply of additive at source thereof. The additive pump is shut off when the pH of the scrub liquid being returned to the tank 338 through conduit 337 has a high pH, if the contents in the source become low, electrical power to pump is discontinued or the scrub liquid pump 400 is stopped.
Preferably, the source of scrub liquid additive is maintained at an elevated temperature through the use of a heater 7,30. The heater 730 is caused to be on only if electrical power is supplied thereto, the temperature of the additive liquid therein is low and not high and the contents thereof not low. The heater 730 is shut off when the temperature of the additive liquid therein becomes high.
The presently preferred interlock logic for the scrub liσuid drain of the quench tank 332 is illustrated in Figure 37. The quench tank isolation valve 732 in conduit 340 must be open to accommodate return of scrub liquid from the quench tank to the tank 338. The mentioned isolation valve opens when either the level of scrub liquid in the quench tank is high or the quench tank drain level control is manually actuated. The isolation valve 732 is closed when either the quench tank scrub liquid level becomes low or the hand control is actuated. The presently preferred interlock logic for the demineralized water purge of the quench tank is illustrated in Figure 38. Specifically, the solenoid valve 734 is interposed between the source of demineralized water and the conduit 336 is caused to be open and demineralized water is directed into conduit 336, through the quench tank 332 and along the conduit 340. The demineralized water solenoid valve 734 is caused to open either by appropriate actuation of the related hand control or by reason of the fact that the quench tank off—gas temperature goes high high. The solenoid valve 734 is caused to close thereby terminating the demineralized water purge when either the σuench tank off-gas temperature goes low or the related hand control is actuated.
The presently preferred interlock logic for purging the venturi scrubber with demineralized water is illustrated in Figure 39. Demineralized water is introduced into the conduit 336 upstream of the venturi throat 346 when the demineralized water solenoid valve 736 is open. This opening is on a time delay basis and occurs only when the scrub liσuid pump 400 is on, and the venturi scrub liquid flow is low low. Alternatively, appropriate actuation of the associated hand control for the venturi demineralized water will cause the mentioned flow to occur. Such demineralized water flow is terminated by appropriate manual manipulation of the related hand control or stopping of the scrub liquid pump 400.
The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims

CLAIMS WHAT IS CLAIMED IS:
1. A fluidized bed system for incinerating and calcining in a single vessel substantially all low level radioactive waste emanating from a commercial nuclear power generation facility including solid combustible waste, liσuid waste, and resin and sludge waste, the system comprising: a single vessel containing a fluidized bed in the lower portion thereof and a vapor space in the upper portion thereof; a first segregated hopper means source of solid combustible radioactive waste obtained from a nuclear facility; first path means disposed between the hopper means and the vessel; first selectively operable isolation means disposed along the first path means; first selectively operable waste displacement power means for displacing solid waste along the first path means; a second segregated tank means source of liquid radioactive waste obtained from the nuclear facility; second path means interposed between the tank means and the vessel; second selectively operable isolation means disposed along the second path means ; second selectively operable waste displacement power means for displacing liσuid waste along the second path means; a third segregated source comprising mixing tank means of ion exchange resin and filter sludge radioactive waste obtained from the nuclear facility; third path means interposed between the third mixing tank means and the vessel; third, selectively operable isolation means disposed along the third path ; third selectively operable waste displacement power means for displacing resin and sludge waste along the third path means ; control means for causing, at any point in time , any two of the sources to be entirely isolated and locked out against waste displacement therefrom and any one of the sources to be in waste communication with the interior of the vessel via the related path means ; heater means for selectively elevating the temperature level of the fluidized bed to incinerate or calcine the waste being communicated to the vessel ; means for delivering fluidizing air to the bed material ; exhaust means by which off-gas leaves the vessel .
2. A fluidized bed system according to Claim 1 wherein the exhaust means communicate off-gas to gas cleaning means .
3. A system according to Claim 1 comprising means for regulating the temperature of the fluidized bed to be within the range of on the order of 200°C to 550°C during calcination and 800 °C to 1200°C during incineration .
4. A system according to Claim 1 comprising means for creating and maintaining a pressure slightly below ambient in the vessel .
5. A system according to Claim 1 comprising means to deliver overfire air to the vessel above the bed to enhance combustion.
6. A system according to Claim 1 comprising means for causing the heater means to continue to supply heat to the bed after the temperature thereof is raised to an operable level during resin waste incineration and during liquid waste calcination.
7. A scrub liquid system for removing radioactive particles from off-gas comprising: storage means in which a supply of recirculatable scrub liquid is located; conduit means in which scrub liquid is displaced to and from at least one off-gas site; means causing said displacement of scrub liquid; means at the off-gas site for causing scrub liquid to be sprayed into the off-gas and means accommodating return of the sprayed scrub liquid to the conduit means; means selectively delivering a scrub liquid to the scrub tank; means determining the pH of the recirculated scrub liquid and means adding to the scrub liquid from a source to adjust the pH to a satisfactory level.
8. A fluidized bed system for incinerating and calcining in a single vessel substantially all low level radioactive wastes emanating from a commercial
6. A system according to Claim 1 comprising means for causing the heater means to continue to supply heat to the bed after the temperature thereof is raised to an operable level during resin waste incineration and during liquid waste calcination.
7. A scrub liquid system for removing radioactive particles from off-gas comprising: storage means in which a supply of recirculatable scrub liquid is located; conduit means in which scrub liquid is displaced to and from at least one off-gas site; means causing said displacement of scrub liquid; means at the off-gas site for causing scrub liσuid to be sprayed into the off-gas and means accommodating return of the sprayed scrub liquid to the conduit means; means selectively delivering a scrub liquid to the scrub tank; means determining the pH of the recirculated scrub liquid and means adding to the scrub liσuid from a source to adjust the pH to a satisfactory level.
8. A fluidized bed system for incinerating and calcining in a single vessel substantially all low level radioactive wastes emanating from a commercial nuclear power generation facility including solid combustible waste, liσuid waste, and resin and sludge waste, the system comprising: a single vessel containing a fluidized bed in the lower portion thereof and a vapor space in the upper portion thereof; a first segregated hopper means source of solid combustible radioactive waste obtained from a nuclear facility; first path means disposed between the hopper means and the vessel; first selectively operable isolation means disposed along the first path means; first selectively operable waste displacement power means for displacing solid waste along the first path means; a second segregated tank means source of liquid radioactive waste obtained from the nuclear facility; second path means interposed between the tank means and the vessel; second selectively operable isolation means disposed along the second path means; second selectively operable waste displacement power means for displacing liquid waste along the second path means; a third segregated source comprising mixing tank means of ion exchange resin and filter sludge radioactive waste obtained from the nuclear facility; third path means interposed between the third mixing tank means and the vessel; third selectively operable isolation means disposed along the third path; third selectively operable waste displacement power means for displacing resin and sludge waste along the third path means; control means for causing, at any point in time, any two of the sources to be entirely isolated and locked out against waste displacement therefrom and any one of the sources to be in waste communication with the interior of the vessel via the related path means; heater means for selectively elevating the temperature level of the fluidized bed to incinerate or calcine the waste being communicated to the vessel; means for delivering fluidizing air to the bed material; exhaust means be which off-gas leaves the vessel; means associated with the bottom of the vessel for removal of bed material and means above the bottom of the vessel for adding bed material.
9. A fluidized bed system according to Claim 8 wherein the associated means comprise means for continuously removing a metered quantity of bed material and further comprising means by which clinkers and tramp material are segregated from removed usable bed material and means to return the segregated bed material etiher continuously to the vessel or to place the segregated bed material in storage.
10. A fluidized bed system according to Claim 9 wherein the associated means comprise means for rapid removal and storage of hot bed material.
11. An apparatus for dramatically reducing the volume of low level radioactive wastes emanating from a nuclear facility comprising: means separately storing resin and sludge radioactive waste, and at least one other radioactive waste; means independently delivering said wastes respectively at separate intervals of time to a single incinerating calcining fluidized bed vessel; means selectively varying and controlling the temperature of the fluidized bed to cause substantially complete incineration of the resin and sludge wastes and substantially complete incineration or calcination of the other waste respectively during said intervals of time; means supplying further material to comprise the fluidized bed from time to time to enhance the incineration or calcination above mentioned; means cleansing the off-gas and releasing the off- gas to the atmosphere.
12. A fluidized bed system comprising: a vessel; a fluidized bed in the low portion of the vessel; a vapor space in the vessel above the bed; a plurality of means for sensing the temperature of the bed at several sites within the bed; alarm means which are activated when said bed temperature sensing means detect that the bed temperature has exceeded a predetermined level; a plurality of means for sensing the temperature of the vapor space at several sites within the vessel above the bed; further alarm means which are activated when at least some of said vapor space temperature sensing means detect that the vapor space temperature has exceeded a preselected level; means by which used bed material is selectively removed from the bed and means controlling said removed means.
13. A system according to Claim 12 comprising means for placing material comprising the bed within and means for removing material comprising the bed from the vessel.
14. A system according to Claim 13 further comprising influent means and effluent control means, the influent means comprising means for sizing solid waste delivered to the storage source and control means for regulating operation of the sizing means, the effluent control means comprising means fqr regulating delivery of sized solid waste to the vessel along the path defining means.
15. A system according to Claim 14 wherein: the influent means comprise shredding means, shredder bin means having door means, shredder conveyor means, dust collector means and source influent valve means, the storage source further comprises waste mixing means, and wherein the control means for the influent means comprise means for causing and continuing the operation of the shredding means, the shredder conveyor means and the dust collector means so long as selected ones of the following conditions exist: the source influent means are open, the mixing means are operating, the door means are closed, each of the above—mentioned means are in fact operating and none have stopped or been caused to stop, the contents of the storage source are not high, the temperature of the bin is not high.
16. A system according to Claim 14 further comprising a storage source comprises bin means, waste mixing means, means dispensing solid waste to path defining means, bin contents measuring means, bin temperature sensing means, bin pressure sensing means and means controlling the dispensing means, further comprising power means by which solid waste is displaced, the power means comprising seriatim screw conveyor means adjacent to the dispensing means and pneumatic conveyor means adjacent to the vessel, and further comprising path—defining means between the storage source and the vessel comprising flow control means and means causing and continuing the operation of the storage means and the power means so long as selected ones of the following conditions exist: solid waste is prevented from entering the bin means, the fluidized bed temperature is normal, delivery of fluidizing air to the bed is normal, start of solid waste to the path defining means has been manually initiated, displacement of any other type of waste to the vessel is locked out, the temp erature of solid waste is not high, the flow control means along the path defining means are open, the power means are operating.
17. A system according to Claim 16 comprising means causing the screw and pneumatic conveyor means to continue to operate after stoppage of the dispensing means for a time sufficient to allow all solid waste to be removed therefrom and delivered to the vessel.
18. A fluidized bed system for incinerating and calcining in a single vessel substantially all low level radioactive wastes emanating from a commercial nuclear power generation facility including solid combustible waste, liquid waste, and resin and sludge waste, the system comprising: a single vessel containing a fluidized bed in the lower portion thereof and a vapor space in the upper portion thereof; a first segregated hopper means source of solid combustible radioactive waste obtained from a nuclear facility; first path means disposed between the hopper means and the vessel; first selectively operable isolation means disposed allong the first path means; first selectively operable waste displacement power means for displacing solid waste along the first path means; a second segregated tank means source of liquid radioactive waste obtained from the nuclear facility; second path means interposed between the tank means and the vessel; second selectively operable isolation means disposed along the second path means; second selectively operable waste displacement power means for displacing liquid waste along the second path means ; a third segregated source comprising mixing tank meeans of ion exchange resin and filter sludge radioactive waste obtained from the nuclear facility ; third path means interposed between the third mixing tank means and the vessel ; third selectively operable isolation means disposed along the third path ; third selectively operable waste displacement power means for displacing resin and sludge waste along the third path means ; control means for caus ing , at any point in time , any two of the sources to be entirely isolated and locked out against waste displacement therefrom and any one of the soourcεs to be in waste communication with the interior of the vessel via the related path means ; heater means for selectively elevating the temperature level of the fluidized bed to incinerate or calcine the waste being communicated to the vessel ; means for delivering fluidizing air to the bed material ; exhaust means by which off-gas leaves the vessel ; means causing the fluidizing air to pass through the heater means enroute to the vessel .
19 . A fluidized bed system comprising : a vessel ; a fluidized bed in the low portion of the vessel; a vapor space in the vessel above the bed; a plurality of means for sensing the temperature of the bed at several sites within the bed; alarm means which are activated when said bed temperature sensing means detect that the bed temperature has exceeded a predetermined level; a plurality of means for sensing the temperature of the vapor space at several sites within the vessel above the bed; further alarm means which are activated when at least some of said vapor space temperature sensing means detect that the vapor space temperature has exceeded a preselected level .
20 . A system according to Claim 19 further comprising : logic means interposed between the sensing means and the alarm and further alarm means , the logic means comprising means disregarding any erroneous temperature sensed at at least one of said bed sites and one of said vapor space sites .
21. A system according to Claim 19 comprising off-gas processing means comprising off-gas blower means and means by which ambient air is added to the off -gas prior to stack discharge, and further comprising means sensing off-gas pressure within the vessel vapor space and control means interposed between the pressure sensing means and the ambient air adding means controlling the amount of ambient air added to the off-gas .
22. A system according to Claim 19 comprising off-gas treatment means receiving and processing off-gas egressing from the vapor space , the off-gas treatment means comprising at least selected ones of the following sites : dry solid removal , wet solid removal , scrub liquid addition , filter, condensation , adsorber, humidity reduction , blower , valve and water purge.
23 . A system according to Claim 22 comprising at least selected ones of the following sensors at or adjacent said sites : off-gas flow, off-gas temperature , scrub liquid flow, off-gas pressure , scrub liquid pressure and radiation .
24 . A system according to Claim 23 comprising alarm means activated when one of the following events occur: off-gas pressure drop is high, scrub liquid pressure is low, off-gas flow is low, scrub liquid flow is low, off-gas temperature is high, off-gas radiation level is high .
25. A system according to Claim 23 comprising means causing and continuing operation of the off-gas treatment means so long as selected ones of the following conditions exist: off-gas and scrub liquid valve sites remain open , manual shut down has not occurred , scrub liquid pressures are normal , off—gas and scrub liquid flow rates are normal , off-gas and scrub liquid temperatures are normal , blower off-gas discharge is occurring, execessive radiation has not occurred , the pH of the scrub liquid is normal .
26. A system according to Claim 19 further comprising waste influent means selectively delivering waste to the vessel , fluidized bed burner means , fluidizing air means , off-gas treatment means , bed material discharge means , first alarm means and second alarm means , the first alarm means being activated by at least one of the following events and the second alarm means being activated if the event worsens after activation of the first alarm means and passage of a predetermined interval of time: the amount of waste available is low or high, pressure in the waste influent means is low or high, air pressure is low, the bed temperature is low or high, the vapor space temperature is high , scrub liquid flow is low, off—gas temperature is low or high , off-gas pressure is low, radiation is high, available scrub liquid is low.
27. A method for treating of low level radioactive waste eminating from a commercial nuclear power plant which comprises: providing a single fluidized bed incinerator calcmer wherein the bed material is resistant to oxidization, agglomeration, and attack by chemicals at temperatures up to at least about 1200 °C; providing combustion conditions in the fluidized bed incinerator calciner; feeding into the fluidized bed region of the fluidized bed incinerator calciner at different intervals oftime (a) liσuid waste to be calcined, and (b) resin and sludge waste to be incinerated, and (c) combustible solid waste to be incinerated, fed in above the bed; supplying and controlling fuel and oxygen containing gas to the incinerator calciner to maintain combustion conditions therein for the waste treatment mode being pursued; introducing gas into the fluidized bed region of the incinerator calciner at a velocity sufficient to maintain the bed particles in a fluidized state; incinerating or calcining the waste being fed; passing a gas effluent from said incinerator calciner to dry cyclone means wherein particles are separated from the effluent; removing solid particles from said dry cyclone means and passing them to a storage container; removing a gaseous effluent from the dry cyclone means and passing it to a quench tank; introducing liquid into said quench tank for cooling and wetting particles contained in the gaseous effluent; removing liquid particles from said quench tank and passing them to a scrub solution tank; removing a gaseous effluent from the quench tank and passing it to a venturi scrubber; introducing liquid into the venturi scrubber to wet particles remaining in the gaseous effluent and cause condensation of water vapor; removing a gaseous effluent and wetted particles from the venturi scrubber and passing them to a wet cyclone; removing liquid particles from the wet cyclone and passing the liquid so removed to a scrub solution tank; removing a gaseous effluent from the wet cyclone and passing it to an entrainment separator; removing liquid from the entrainment separator and passing it to a scrub solution tank; removing a wetted, gaseous effluent from the entrainment separator and passing it to a condenser for condensing liquid vapor; removing a gaseous effluent and condensed liquid particles from the condenser and passing them to a mist eliminator; removing liquid particles from the mist eliminator and passing them to a scrub solution tank; removing a gaseous effluent from the mist eliminator and passing it to a heater for raising the temperature of the effluent to reduce the relative humidity; passing the heater effluent through a filter for removal of remaining solid particles and through an adsorber to remove iodine therefrom.
28. The method of Claim 27 wherein said calcining is carried out at about 200-550°C.
29. The method of Claim 27 wherein said incinerating is carried out at about 800-1200°C.
30. The method of Claim 27 wherein liquid introduced into said quench tank is from said scrub solution tank.
31. The method of Claim 27 wherein liquid introduced into said venturi scrubber is from said scrub solution tank .
32. A system according to Claim 27 wherein a base is added to liquid wastes containing boric acid allowing it to be calcined in a fluidized bed .
33. A method for treating of low level radioactive waste eminating from a commercial nuclear power plant which comprises : providing a single fluidized bed incinerator calciner wherein the bed material is resistant to oxidation, agglomeration , and attack by chemicals at temperatures up to at least about 1200 °C ; providing combustion conditions in the fluidized bed incinerator calciner; feeding into the fluidized bed region of the fluidized bed incinerator calciner at different intervals of time (a) liquid waste to be calcined , and (b) resin and sludge waste to be incinerated , and (c) combustible solid waste to be incinerated , fed in above the bed ; supplying and controlling fuel and oxygen containing gas to the incinerator calciner to maintain combustion conditions therein for the waste treatment mode being pursued ; introducing gas into the fluidized bed region of the incinerator calciner at a velocity sufficient to maintain the bed particles in a fluidized state ; incinerating or calcining the waste being fed ; passing a gas effluent from said incinerator calciner to dry cyclone means wherein particles are separated from the effluent ; removing solid particles from said dry cyclone means and passing them to a storage container ; removing a gaseous effluent from the dry cyclone means and passing it to a quench tank; introducing liquid into said quench tank for cooling and wetting particles contained in the gaseous effluent; removing liquid particles from said quench tank and passing them to a scrub solution tank; removing a gaseous effluent from the quench tank and passing it to a venturi scrubber; introducing liquid into the venturi scrubber to wet particles remaining in the gaseous effluent and cause condensation of water vapor; removing a gaseous effluent and wetted particles from the venturi scrubber and passing them to a wet cyclone; removing liquid particles from the wet cyclone and passing the liquid so removed to a scrub solution tank; removing a gaseous effluent from the wet cyclone and passing it to an entrainment separator; removing liquid from the entrainment separator and passing it to a scrub solution tank; removing a wetted gaseous effluent from the entrainment separator and passing it to a condenser for condensing liquid vapor; removing a gaseous effluent and condensed liquid particles from the condenser and passing them to a mist eliminator; removing liquid particles from the mist eliminator and passing them to a scrub solution tank; removing a gaseous effluent from the mist eliminator and passing it to a heater for raising the temperature of the effluent to reduce the relative humidity; passing the heater effluent through a filter for removal of remaining solid particles and through an adsorber to remove iodine thereform; adjusting the size of the throat of the venturi scrubber to substantially maintain a constant pressure drop notwithstanding variations in flow rate through the throat.
34. A radioactive off-gas cleansing system comprising a venturi scrubber, the improvements comprising a variable throat and means for remotely adjusting the size of the throat to substantially maintain a constant pressure drop across the venturi scrubber notwithstanding variations in the flow rate therethrough.
35. A cleansing system according to Claim 34 wherein the venturi scrubber comprises a hollow entry cone and a hollow discharge cone respectively disposed fore and aft of the throat.
36. A cleansing system according to Claim 34 wherein the throat comprises a flap, the angle of which is changed from time to time by said remote adjusting means to vary the size of the throat.
37. An off-gas cleansing system according to Claims 34 wherein the remote adjusting means comprise opposed threaded roads.
38. An off-gas cleansing system according to Claim 34 wherein the remote adjusting means comprise reciprocable power means.
39. An off-gas cleansing system according to Claims 34 comprising means for receiving scrub liquid and means for discharging the scrub liquid as a spray into the venturi scrubber.
40. An off-gas cleansing system according to Claim 34 comprising means placing at least part of the off-gas system at a slightly negative pressure.
41. A radioactive waste feed system comprising: segregated sources of solid combustible radioactive waste, liquid radioactive waste, and resin and sludge radioactive waste; segregated path means spanning between the respective sources in the vessel; flow control means accommodating displacement of any one waste and preventing displacement of the other two wastes along the associated path means to the vessel at any point in time; power means by which the selected waste is displaced to the vessel; means for controlling and varying the temperature of the fluidized bed to incinerate either the combustible waste or the resin and sludge waste and to calcine the liquid waste; means for changing bed materials, at least after incineration of resin waste.
42. A radioactive waste feed system according to Claim 41 further comprising resin waste dewatering means and means interposed between the dewatering means and the liquid waste source along which the dewatered substance is displaced.
43. A heating system for elevating the temperature of and fluidizing a fluidized bed comprising an external enclosed burner; cooling effluent annulus means downstream of, adjacent to and in pneumatic cσmmunciation with the burner; a fluidizing air conduit in pneumatic communication with the annulus means and adapted to communicate fluidizing air to an incinerating or calcining fluidized bed; the annulus means comprising port means through which cooling air introduced and circuitous channel means within the annulus means defining a cooling air flow path which joins with and becomes part of the fluidizing air; combustion fuel influent means to the burner; fuel atomizing air influent means to the burner; combustion air influent means to the burner; start up fuel influent means and control means causing utilization of the respective start up fuel influent and combustion fuel influent solely at separate points in time.
44 . A system according to Claim 43 further comprising a fluidized bed vessel, temperature sensing means in the vessel and means responsive to the temperature means regulating the amount of combustion fuel introduced into the burner to thereby derive an amount of heat in the fluidizing air sufficient to produce a desired bed temperature.
45. A system according to Claim 44 further comprising means responsive to the flow rate of combustion fuel in the combustion fuel influent means and changes therein and control means in communication with the responsive means to correspondingly regulate the flow of air in the atomizing air influent means and the combustion air influent means.
46. A system according to Claim 43 further comprising means selectively regulating the rate of air flow through the port means.
47. A fluidized bed system comprising: a vessel; a fluidized bed in the low portion of the vessel; a vapor space in the vessel above the bed; a plurality of means for sensing the temperature of the bed at several sites within the bed; alarm means which are activated when said bed temperature sensing means detect that the bed temperature has exceeded a predetermined level; a plurality of means for sensing the temperature of the vapor space at several sites within the vessel above the bed; further alarm means which are activated when at least some of said vapor space temperature sensing means detect that the vapor space temperature has exceeded a preselected level. burner means associated with the fluidized bed and control means interposed between the bed temperature sensing means and the burner means to control the amount of heat delivered to the bed by the burner means.
48. A system according to Claim 47 comprising means by which waste is selectively delivered to the fluidized bed within the vessel for incineration or calcination.
49. A system according to Claim 48 wherein said selective delivery means comprise a storage source for solid combustible waste and path defining means between the storage source and the vessel along which the solid combustible waste is displaced by power means.
50. A system according to Claim 48 wherein said selective delivery means comprise a storage source for wet resin waste and path-defining means between the storage source and the vessel along which the resin waste is displaced by power means.
51. A system according to Claim 50 comprising influent control means and effluent control means, the influent control means comprising influent valve means selectively allowing resin waste to be delivered to the storage means, the effluent control means comprising effluent valve means, and pneumatic conveyor means, the power means comprising effluent pump means and blower means together accommodating and regulating flow of resin waste along the path-defining means.
52. A system according to Claim 51 further comprising dewatering means associated with. the storage means whereby liquid is removed from the resin waste before the resin waste is caused to be displaced along the path defining means.
53. A system according to Claim 51 wherein the storage means comprise contents-sensing means and further comprising regulating means interposed between the contents sensing means and the influent valve means whereby the contents of the resin waste storage source controls the amount of resin waste ingressing to the storage means.
54. A system according to Claim 51 wherein the effluent control means comprise a means of regulating displacement of resin waste by the pump means, means controlling the state of the effluent valve means and a means controlling the air flow created by the blower means and further comprising alarm means activated when the flow of air caused by the blower is unacceptably low.
55. A system according to Claim 52 wherein said dewatering flow path means are bifurcated at least in part accommodating dewatering when resin waste is and is not being displaced along the path-defining means, respectively.
56. A system according to Claim 51 comprising means causing and continuing the operation of the resin waste effluent control means and the pump means so long as selected ones of the following conditions exist: adequate pump and pneumatic pressures on the effluent resin waste exist, the operation is not manually stopped, all valve sites along the path-defining means and along the pnuematic conveyor means are open, the fluidized bed temperature is acceptable, the contents of the resin waste storage source are being mixed, a fluidized bed burner is operative, fluidizing air is adequately supplied, the contents of the resin waste storage source are adequate.
57. A system according to Claim 56 further comprising burner means exterior of the vessel and fuel influent means to the burner means comprising valve means and regulating means interposed between, the fuel influent valve means and bed temperature sensing whereby the temperature of the bed controls the amount of fuel delivered to the burner.
58. A system according to Claim 57 wherein the air influent means comprise atomizing air influent means, combustion air influent means, cooling air influent means and further comprising means regulating in coordination the flow of at least atomizing air, combustion air and cooling air to the burner.
59. A system according to Claim 58 further comprising sensing means detecting the fuel rate and each air flow rate and alarm means activated when at least one selected flow rate is unacceptably low.
60. A system according to Claim 57 comprising temperature sensing means detecting the discharge of the burner and alarm means activated if the discharge temperature is unacceptably low.
61. A system according to Claim 58 comprising means for causing and continuing the operation of the burner means so long as selected ones of the following conditions, exist: a burner flame, air and fuel to the burner exist, the temperature of the vessel vapor space is not high, the temperature of the fluidized bed is not high, the fluidizing air flow is not low, the off-gas temperature and scrub liquid flow conditions are normal and manual cessation has not occurred.
62. A radioactive waste feed system according to Claim 41 wherein the power means comprise:
(a) an auger associated with the source of solid combustible waste and a pneumatic conveyor interposed between the discharge end of the auger and the vessel,
(b) a pump associated with the source of resin waste and a second pneumatic conveyor interposed between the pump discharge and the vessel, and
(c) A second pump associated with the source of liσuid waste and a liquid conveyor interposed between the second pump and the vessel.
63. A system according to Claim 48 wherein said selective delivery means comprise a storage source for liσuid waste and path-defining means between the storage source and the vessel along which the liquid waste is displaced by power means.
64. A system according to Claim 63 further comprising influent control means and effluent control means, the influent control means comprising influent valve means selectively allowing liquid waste to be delivered to the storage source, the effluent control means comprising effluent valve means, and strainer means, the power means comprising effluent pump means accommodating and regulating flow of liquid waste to the vessel along the path defining means and return flow means between the strainer and the storage source
65. A system according to Claim 64 wherein the storage source comprises contents sensing means and further comprising regulating means interposed between the contents sensing means and the influent valve means whereby the contents of the liquid waste storage source controls the amount of liquid waste ingressing to the storage source.
66. A system according to Claim 64 wherein the effluent control means comprise liquid waste flow and pressure sensing means, atomizing air means and alarm means whereby the flow and pressure sensing means concurrently regulate in coordination the pump means and the atomizing air means, the alarm means being by unacceptabley high and unacceptably low pressure and unacceptably low liquid flow and unacceptably low atomizing air flow.
67. A system according to Claim 64 further comprising water purge means for selectively flushing the path-defining means.
68. A system according to Claim 66 comprising means causing and continuing the operation of the effluent control means and the pump means so long as selected ones of the following conditions exist: liquid waste atomizing air into the fluidized bed is occurring, adequate pressure on the effluent liquid waste exists, the operation is not manually stopped, all valve sites along the path-defining means are open, a fluidized bed burner is operative, the contents of the storage source are not unacceptably low, fluidizing air is adequately supplied and the temperature of the bed is adequate.
69. A fluidized bed material handling system comprising: a fluidized bed vessel; means by which bed material is introduced into the vessel; means by which used bed material is removed from the vessel; means by which clinkers and other tramp material are segregated from removed bed material; first path defining means along which segregated bed material is thereafter selectively displaced to the vessel introduction site; second path defining means along which segregated bed material is thereafter selectively displaced to a bed material storage site; power means for so displacing the segregated bed material to either of said two sites; control means by which the segregated bed material is caused to be displaced by the power means to either of said sites.
70. A fluidized bed material handling system according to Claim 69 further comprising storage means for new bed material and means by which new bed material is selectively metered from said new bed material storage site to the vessel.
71. A fluidized bed material handling system according to Claim 69 wherein the segregated bed material storage site comprises a plurality of separate storage facilities and further control means for placing different bed material in separate storage facilities respectively at different times.
72. A fluidized bed material handling system according to Claim 69 further comprising rapid bed material discharge means and storage means whereby the hot fluidized bed within the vessel may be caused to be rapidly discharged, stored and cooled remote from the vessel.
73. A method according to Claim 69 wherein the discharge is restricted solely to clean off-gas and solid radioactive materials.
74. A fluidized bed material handling system comprising: a vessel; at least two sites where different bed materials are respectively stored, each in a quantity sufficient to substantially form an operable fluidized bed when placed within the vessel; control means by which either storage site is selected as a source for forming a fluidized bed within the vessel; means for causing the selected bed material to be displaced from its storage site to the interior of the vessel; means for replenishing, in the vessel, bed material lost due to attrition.
75. A fluidized bed material handling system according to Claim 74 further comprising means for removing used bed material from the vessel, segregating tramp material therefrom and optionally placing the segregated bed material in storage or returning it to its initial storage vessel.
76. An incineration fluidized bed vessel comprising seriatim an interior metal layer, an air space and another layer adjacent the air space and further comprising means by which air is caused to be displaced along the air space during incineration whereby the temperature of the interior metal layer is cooled so as not to exceed 650°C.
77. A vessel for fluidized bed incineration and calcination comprising a dry cyclone receiving off-gas from the vessel, the vessel and the dry cyclone respectively comprising an inner metal alloy layer comprising on the order of by weight: 50-80% nickel, 15-23% chromium, 2-19% iron, 0-9% molybdenum and 0-6% niobium and tantalum.
78. A heating system for elevating the temperature of and fluidizing a fluidized bed comprising an external enclosed burner; cooling effluent annulus means downstream of, adjacent to and in pneumatic communication with the burner; a fluidizing air conduit in pneumatic communication with the annulus means and adapted to communicate fluidizing air to an incinerating or calcining fluidized bed; the annulus means comprising port means through which cooling air introduced and circuitous channel means within the annulus means defining a cooling air flow path which joins with and becomes part of the fluidizing air; combustion fuel influent means to the burner; fuel atomizing air influent means to the burner; combustion air influent means to the burner.
79. A system according to claim 78 further comprising overfire air conduit means adapted to selectively deliver air to one or more sites above the fluidized bed.
80. A system according to Claim 78 further comprising fluidized bed burner means, exterior of the vessel for delivering heat to the bed, the burner means comprising a burner, burner effluent means, fuel influent means and air influent means.
81. A radioactive off-gas cleansing system, the improvement comprising an iodine adsorber comprising housing means through which off-gas is passed, the off-gas influent of which contains radioactive iodine, and filter means contained within the housing means, the filter means comprising fore and aft porous retainers, silver loaded silica gel beads or activated carbon loaded with potassium iodide and an amino disposed between the porous retainers, and transverse inlet and outlet port means for introducing and removing the beads under remote control, radioactive iodine being adsorbed as the off-gas passes therethrough, which radioactive iodine thereafter decays to xenon, thereby eliminating the use of a cartridge and the seals used with a cartridge which eliminates the possibility of bypass leakage.
82. A method according to Claim 81 further comprising means for introducing kaolin clay into the vessel during resin incineration whereby the formation of low melting point materials is avoided during incineration and the resulting coating of parts within the process vessel.
83. A method of reducing the volume of at least two wastes to be disposed of in a single fluidized bed comprising the steps of: introducing a quantity of first bed material to a fluizied bed vessel; elevating the temperature of fluidized bed in the vessel;
72. A fluidized bed material handling system according to Claim 69 further comprising rapid bed material discharge means and storage means whereby the hot fluidized bed within the vessel may be caused to be rapidly discharged, stored and cooled remote from the vessel.
73. A method according to Claim 69 wherein the discharge is restricted solely to clean off-gas and solid radioactive materials.
74. A fluidized bed material handling system comprising: a vessel; at least two sites where different bed materials are respectively stored , each in a quantity sufficient to substantially form an operable fluidized bed when placed within the vessel ; control means by which either storage site is selected as a source for forming a fluidized bed within the vessel ; means for causing the selected bed material to be displaced from its storage site to the interior of the vessel ; means for replenishing, in the vessel , bed material lost due to attrition .
75 . A fluidized bed material handling system according to Claim 74 further comprising means for removing used bed material from the vessel , segregating tramp material therefrom and optionally placing the segregated bed material in storage or returning it to its initial storage vessel . fluidizing the bed; introducing a first waste into the bed whereby the first waste is substantially incinerated or calcined; removing the first bed material from the vessel and replacing it with a second bed material the quantity of which is sufficient to create another fluidized bed in the vessel; elevating the temperature of the second fluidized bed in the vessel; fluidizing the second bed; introducing a second different waste into the second bed whereby the second waste is substantially incinerated or calcined.
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