WO2000004983A1 - Procede et appareil de recuperation de gaz acides de gaz de fumee - Google Patents

Procede et appareil de recuperation de gaz acides de gaz de fumee Download PDF

Info

Publication number
WO2000004983A1
WO2000004983A1 PCT/US1999/016518 US9916518W WO0004983A1 WO 2000004983 A1 WO2000004983 A1 WO 2000004983A1 US 9916518 W US9916518 W US 9916518W WO 0004983 A1 WO0004983 A1 WO 0004983A1
Authority
WO
WIPO (PCT)
Prior art keywords
flue gas
temperature
alkaline reagent
solids
selecting
Prior art date
Application number
PCT/US1999/016518
Other languages
English (en)
Inventor
Ronald W. Bayliss
Original Assignee
Spray Drying Systems, 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 Spray Drying Systems, Inc. filed Critical Spray Drying Systems, Inc.
Priority to AU52215/99A priority Critical patent/AU5221599A/en
Publication of WO2000004983A1 publication Critical patent/WO2000004983A1/fr

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/34—Chemical or biological purification of waste gases
    • B01D53/46—Removing components of defined structure
    • B01D53/48—Sulfur compounds
    • B01D53/50—Sulfur oxides
    • B01D53/501—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound
    • B01D53/504—Sulfur oxides by treating the gases with a solution or a suspension of an alkali or earth-alkali or ammonium compound characterised by a specific device
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
    • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
    • B01D53/1456—Removing acid components

Definitions

  • the present invention is directed to a process and an apparatus for treating flue gases. More particularly, the present invention is directed to a process and an apparatus for the reduction and/or removal of one or more acid gas pollutants such as SO 2 , HCl, HF, HBr, NOx, and/or solids including particulate matter from flue gases typically generated by the combustion of sulfur containing coal including high sulfur coal, incineration of hazardous medical and municipal wastes, glass and metal thermal treating processes, and the like.
  • acid gas pollutants such as SO 2 , HCl, HF, HBr, NOx, and/or solids including particulate matter from flue gases typically generated by the combustion of sulfur containing coal including high sulfur coal, incineration of hazardous medical and municipal wastes, glass and metal thermal treating processes, and the like.
  • wet scrubbers are the most efficient of all known systems because the gases are fully water saturated at the wet bulb temperature. This wet bulb temperature condition is one of the best known for absorption and subsequent reaction of the acid gases with an alkaline reagent.
  • Wet scrubbers suffer from disadvantages which include, but are not limited to, the following: (1) the wet scrubber vessels that "contain" the process are designed based on low internal flue gas velocities of 200 to 500 feet per minute which requires the use of high cross-sectional area equipment which, in turn, contributes to high equipment costs; (2) large quantities of wet slurries are produced which require expensive pumping and disposal systems; (3) careful pH control is necessary to effect difficult recovery of the acid gases; (4) because the system is wet, expensive corrosion resistant parts (e.g., stainless steel, fiber glass and other alloy parts) must be used; and (5) periodic cleaning is required to combat the effects of solids buildup including scaling, plugging, fouling and/or corrosion of equipment.
  • Spray drying systems are a combination of wet and dry processes in which an alkaline reagent is injected as a wet water slurry (sometimes as an overly wet slurry) that is dried as part of the process, resulting in a dry solid for disposal. Therefore, spray drying is classified as a semi-dry process.
  • Spray dryers generally use a water slurry of hydrated lime as a feed reactant stream.
  • the spray drying process cools the flue gas from its initial temperature (e.g., boiler flue gas outlet temperature) to a controlled outlet temperature (i.e., temperature of the gas entering a solids recovery filter) typically about 50 degrees F above the flue gas saturation temperature.
  • the saturation temperature is the flue gas temperature at which it contains the maximum amount of water vapor i.e., the wet bulb temperature.
  • the fixed amount of water limits the concentration of hydrated lime that can be pumped and atomized.
  • the effluent stream to disposal is a dry solid.
  • the efficiency of a spray drying system may vary from about 70% up to as high as 90%.
  • Spray dryers are designed to use low internal flue gas velocities, 75 to 250 feet per minute, which results in the use of high cross-sectional area vessels contributing to increased capital costs. Further, as with all systems, to obtain higher cleaning efficiencies, it is necessary to operate spray drying systems close to the saturation temperature. To increase the acid removal efficiency, the flue gas temperature is lowered to approach the saturation temperature. The closer the temperature of the flue gas to the saturation temperature (especially below the saturation temperature when water condenses out of the flue gas), the higher the water content of the flue gas together with that of the alkaline reagent. As a consequence of the increased water content, the solids buildup problems including scaling, plugging, fouling and/or corrosion on the inner walls of the spray drying apparatus become exacerbated.
  • Dry injection systems are promoted as the newest technique for recovery of acid gases from flue gases.
  • dry reagent is injected directly into the boiler combustion zone, ducts or into a special vessel to react with the flue gases.
  • the known dry injection systems require a high excess of dry reagent and are, therefore, inefficient and expensive to operate.
  • an object of the present invention to provide a process (together with an apparatus for implementing the process) for cleaning flue gases that reduces one or more of the aforementioned problems associated with wet scrubbers, semi-dry scrubbers and/or dry injection systems.
  • the flue gas is traveling at a high flue gas velocity (e.g., from about 2500 to about 4500 feet per minute) and the pulverizing, contacting and mixing step is carried out within the mill and optionally completed within the ductwork leading to a solids recovery filter used in the separating step.
  • a high flue gas velocity e.g., from about 2500 to about 4500 feet per minute
  • the apparatus for cleaning a flue gas containing an amount of one or more acid gas pollutants including particulate matter comprises:
  • Figure 1 is a schematic of a preferred apparatus according to one embodiment of the invention.
  • flue gas may encompass one or more flue gases and solids that may be present.
  • flue gas is a combination of one or more gases and entrained solids such as fly ash which is produced by the combustion of, for example, high sulfur coal in a boiler steam generator, or the like, normally associated with the generation of electricity.
  • High sulfur coal refers to coal containing more than about 3-4% sulfur, by weight (measured as elemental sulfur).
  • a typical "flue gas" leaving a boiler contains from about 1 ,200 parts per million (ppm) to about 2,500 ppm SO 2 , from about 0.01 to about 0.08 grains/standard cubic foot (scf) particulate matter, and from about 200 ppm to about 400 ppm of NO .
  • Typical values may be 2,000 ppm SO 2 , 0.05 grains/scf particulate matter and 300 ppm NO .
  • the flue gas typically leaves a boiler at a temperature T, from about 320 °F to about 700 °F, more typically at a temperature T, from about 325 °F to about 375 °F.
  • Alkaline reagent refers to a source of lime, a source of hydrated lime, mixtures thereof or equivalents thereof which have been wetted with an appropriate amount of a fluid, typically liquid water, to permit further cooling of and reaction with a partially cooled and humidified flue gas when the alkaline reagent is pulverized, contacted and mixed with the flue gas.
  • the further cooling of the partially cooled and humidified flue gas is from a set point temperature of T 2 down to a lower temperature T 4 which is above the wet bulb temperature T 3 of the flue gas.
  • the amount of fluid added to prepare the alkaline reagent is sufficient to maintain T 4 above the wet bulb temperature T 3 of the flue gas and which amount of fluid substantially avoids solids buildup including scaling, plugging, fouling, and/or corrosion of the process equipment.
  • the process of the present invention comprises four broadly categorized operations: (1) preliminary gas conditioning, i.e., partial gas cooling and humidification; (2) alkaline reagent preparation; (3) contacting the conditioned flue gases with the alkaline reagent; and (4) separating particulate matter from the treated flue gas.
  • preliminary gas conditioning i.e., partial gas cooling and humidification
  • alkaline reagent preparation i.e., contacting the conditioned flue gases with the alkaline reagent
  • (4) separating particulate matter from the treated flue gas i.e., partial gas cooling and humidification
  • An initial step in the inventive process involves preliminary conditioning of the flue gas.
  • the flue gas is partially cooled and humidified, preferably by spraying a fluid into the, typically hot, flue gas. In a preferred embodiment, this may be accomplished, for example, by spraying water into the flue gas. Other methods for introducing water droplets including atomized water into the flue gas may be used. Such methods are well known to those of ordinary skill.
  • the flue gas is cooled to a temperature above the saturation temperature with an amount of water that avoids solids buildup including scaling, plugging, fouling and/or corrosion of the inventive apparatus. Avoidance of corrosion is especially critical during preliminary conditioning (i.e., partial cooling and humidifying) of the flue gas because of the high acid content entrained therein.
  • This preliminary conditioning is accomplished by introducing a minimum amount of water that is necessary to cool the flue gas to the desired temperature while maintaining essentially dry the internal surfaces of the inventive apparatus. While the cooling and humidifying fluid is discussed in terms of water, water in combination with other liquids and/or solids may be used. However, water is generally preferred.
  • Atomization of water into the flue gas for cooling and humidifying the flue gas is preferably accomplished by the use of one or more pressure nozzles connected to one or more pumps including positive displacement pumps.
  • This atomization method is preferred because (1) the energy consumption per unit weight of water sprayed, for a given droplet size, is the lowest possible; (2) a high mechanical mixing efficiency is achieved; and (3) the water spray pattern is easily and reliably controlled.
  • other atomization methods may be used. These include, but are not limited to utilizing one or more "two fluid" nozzles using steam or compressed air as the energy source for atomization.
  • an exemplary flue gas volume of 1,074,000 actual cubic feet per minute (acfm) from an exemplary coal fired 300 megawatt boiler three water pumps may be provided for spraying water from about 50 spray nozzles. Typically, two water pumps are operating, while one is on standby. Flow control is preferably accomplished by the use of variable speed drives.
  • the flue gas typically is cooled from an exemplary initial temperature Ti of about 325 °F down to an exemplary cooled temperature T 2 of about 170°F, a preferred set point for this process step.
  • the T 2 set point is a primary variable that is preferably fixed based on the system water (or other fluid) saturation temperature T 3 which typically varies with the ambient combustion conditions including water content of solids combusted, hydrogen content of the solids combusted, and ambient temperature and humidity. This T 3 temperature is continuously monitored with feed back control to set or reset T 2 to maintain T 2 above T 3 .
  • a sufficient amount of alkaline reagent e.g., fresh alkaline reagent plus any recovered/recycled alkaline reagent and any recovered/recycled particulate matter together with their respective water content
  • T 4 is added to lower the flue gas temperature from T 2 to a temperature T 4 which approaches T 3 preferably as close as practically and economically possible with the proviso that T 4 ⁇ T 3 .
  • T 3 is denoted as the wet bulb temperature.
  • T 4 is selected by the value of T 3 subject to the aforementioned proviso that T 4 > T 3 .
  • the temperature differential between T 4 and T 3 is, typically from about 5 to about 20 °F above T 3 .
  • the initial flue gas acid content and T 3 are quantified. Based on these quantified values, a desired T 4 is selected that will permit the acid removal efficiency desired as described below.
  • the flue gas volume, its composition and selected T 4 will dictate the T 2 value necessary to achieve the desired acid removal efficiency. Subject to the aforementioned criteria and conditions, T 2 is appropriately preselected. Once T 2 is selected, the differential temperature T 2 - T 4 is readily calculated. The differential temperature dictates the quantity of water necessary to lower T 2 to T 4 .
  • the aforementioned quantity of water necessary to lower T 2 to T 4 is combined with the source of lime (or hydrated lime) to yield an alkaline reagent.
  • the necessary quantity of the source of lime is dictated by the initial flue gas acid content.
  • the water content (e.g., % by weight water based on the total weight of the water and the source of lime) of the alkaline reagent shall not exceed the point at which solids buildup including scaling, plugging, fouling and/or corrosion of equipment becomes problematic (i.e., the alkaline reagent does not exhibit substantially free-flowing properties) with regard to the inventive apparatus.
  • all % values are by weight based on the total weight of the alkaline reagent.
  • the cooled and humidified flue gas temperature T 2 is maintained from about 10 to about 45 degrees above T 4 .
  • the water added during the cooling and humidifying step should be limited by the preferred requirement of maintaining T 2 from about 10 to about 45 degrees F above T 4 .
  • the water content of the alkaline reagent be limited typically from about 1% to about 15%, more typically from about 2% to about 12%, preferably from about 3% to about 1 1%, and more preferably from about 5% to about 10%.
  • water is preferred, other liquids and/or solids may be used to lower T 2 to T 4 at varying levels of fluid content sufficient to permit substantial free-flow of the alkaline reagent and the flue gas together with its particulate matter throughout the inventive apparatus.
  • the total quantity of the alkaline reagent (having the appropriate water/fluid content) may be varied as necessary during the pulverizing, contacting and mixing step of the inventive process (see section (3) below).
  • T 2 i.e., set
  • T 4 i.e., smaller temperature differential of (T 2 - T 4 )
  • T 2 may be raised (i.e., set) closer to T, (i.e., larger temperature differential of (T 2 - T 4 )) when it is preferred to increase the water content of the alkaline reagent while maintaining the free flowing properties (i.e., absence of solids dropout) of the flue gases and other material flowing within the apparatus of this invention.
  • the function of the water is to wet the surface of the alkaline solids to enhance reaction with the acid gas or gases. Ultimately, as the water evaporates, the flue gases are further cooled towards T 4
  • T the required amount of heat transfer (for 1,074,000 acfm of flue gas) is about 1 19,149,000 British thermal units per hour (Btu/hr), which requires about 108,195 pounds of water per hour (lb/hr) or about 222.6 gallons per minute (GPM).
  • This volume of water requires the use of about 50 spray nozzles to achieve effective atomization of the water as well as for proper mixing with the gas to achieve sufficient cooling and humidification of the gas.
  • the number of nozzles, the flow rate of the water, and/or the number of pumps used can be readily adjusted, upwards or downwards, depending on the quantity of the flue gas to be cleaned, its acid gas content, and the volume of water to be sprayed to obtain the desired cooling and humidity prior to mixing the flue gas with the alkaline reagent and any recovered/recycled solids. While the above noted calculations are discussed in terms of the number of spray nozzles, one or more spray nozzles, pressure or "two-fluid" nozzles or the like may be used.
  • the initial temperature T, of the flue gas is a function of, for example, the boiler outlet temperature set point.
  • the T 2 set point is selected as a function of the flue gas water saturation temperature T 3 and the desired acid gas pollutant removal efficiency.
  • the saturation temperature T 3 is a function of the total combustion air used, ambient temperature and humidity, and the hydrogen and water content of the coal.
  • the saturation temperature T 3 is also a function of the combustion air used, ambient humidity and, in this case, the hydrogen content of the waste(s) and the free water content.
  • the transport ducts from the boiler, generator, incinerator or the like should preferably be large enough to permit direct spraying of a fluid, preferably water, into the flue gas without substantially reducing the flue gas velocity or without having to rely upon any special mixing techniques. Additionally, it is preferred that the flue gas velocity should be sufficiently high to prevent solids dropout, e.g., from about 2500 to about 4500 feet per minute. For the aforementioned flue gas volume, a vessel and/or duct having a diameter of about 20 feet and a length of about 90 feet is sufficient.
  • vessel and/or duct diameters and lengths may be used in combination which are sufficient to permit cooling and humidifying of the flue gas while maintaining a flue gas velocity sufficient to prevent substantial solids buildup or solids dropout.
  • the above-noted diameters and lengths should be of sufficient size to permit substantially total evaporation of the water content (or other fluid content) to occur.
  • one or more of the acid gas pollutants in the flue gas are reduced to an acceptable level by intimately contacting and mixing the flue gas with the alkaline reagent, preferably pulverized alkaline reagent.
  • the flue gas temperature immediately prior to this contacting and mixing step is at the set point T 2 .
  • a suitable alkaline reagent preferably lime or hydrated lime together with or without recovered/recycled solids
  • a suitable alkaline reagent is pulverized and, preferably essentially simultaneously, intimately contacted and mixed with the partially cooled and humidified flue gas.
  • high levels of acid gas removal can be achieved.
  • the alkaline reagent and any recovered/recycled solids come in contact with the flue gas at a high velocity for a period of time sufficient to react with and reduce the acid gas pollutants (including SO 2 ) in the flue gas to acceptable levels.
  • a reduction in sulfur pollutants by 85% or more is acceptable.
  • a reduction of 90% or more is preferred, a reduction of 90-94% is even more preferred, and a reduction of 95 to 99-100% is most preferred.
  • reductions of 95-100% are readily achievable. While a reduction of 95- 100% might appear negligibly larger than a 90% reduction, it is to be understood that as reduction efficiencies approach 100%, the incrementally better efficiencies are both increasingly more difficult and more expensive to achieve. However, reaching such removal efficiencies are well within the scope of the claimed invention at a cost that is not prohibitively expensive.
  • a suitable alkaline reagent e.g., desulfurizing agent to which an appropriate amount of water or other suitable fluid has been added in accordance with section (2) above
  • a calcium alkali (optionally together with a calcium-reactive silica or alumina) in amounts sufficient to allow for reaction (e.g., chemical reaction, absorption and/or adsorption) with one or more of the acid gases present in the flue gas; (2) virtually any composition which includes a calcium alkali (CaO or Ca(OH) 2 ) and which does not interfere with one or more objects of the present invention; (3) calcium alkali in the form of ( ) lime, ( / ' ) slaked lime, (Hi) hydrated lime, (iv) calcidic lime, (v) dolomitic lime, (vi) calcium hydroxide, (vii) calcium oxide, and/or ( iii) fly ash. Items (/) and (/ ' ) slaked lime, (Hi) hydrated lime, (iv
  • Fly ash is a natural-by-product of coal combustion.
  • the amount of the alkaline content of the fly ash inherently and naturally present in the flue gas reduces the amount of the alkaline reagent (e.g., made from wetting lime or hydrated lime) required to achieve an acceptable reduction of one or more acid gas pollutants (e.g., SO 2 ) from the flue gas.
  • the alkaline reagent e.g., made from wetting lime or hydrated lime
  • SO 2 acid gas pollutants
  • flue gas 10 from a boiler, generator, incinerator, or the like of a power plant is directed via conduit 20 past spray nozzles 30 spraying water 40 which partially cools and humidifies the flue gas 10 from an initial temperature T, to a set point temperature T 2 .
  • a mill 50 suitable for use with the present invention includes, but is not limited to a cage mill, a mixing mill, a rotary mill, a non-rotary mixer, or a high velocity mixer (e.g., Venturi mixer). Two or more mills appropriately connected to conduits 20a, 20b and 59b in a series or parallel configuration may be optionally used.
  • An exemplary, preferred mill suitable for use in conjunction with this invention is a rotary cage mill. See, for example, U.S. Patent No. 4,378,911, incorporated herein by reference in its entirety, for a description of a suitable rotary mill. While a rotary mill may be used, any rotating machine or component that adequately pulverizes the alkaline reagent and provides the intimate mixing and contact between the flue gas 10a and the pulverized alkaline reagent together with any recovered/recycled solids (in the presence of the cooled and humidified flue gas 10a) may be used.
  • a cage mill that contains a rotating cage in a suitable housing which mixes, deagglomerates and/or optionally pulverizes or optionally further pulverizes the alkaline reagent together with any recovered/recycled solids in the presence of the cooled and humidified flue gas 10a may be used.
  • Mill 50 is connected to (1) wetting unit 70, (2) one or more supply containers 60, 60a and 60b containing, for example, dry lime or dry hydrated lime, and (3) recovery solids filter 80 via tubes (e.g., pipes) 25, 25a and screw conveyors 28.
  • the dry reagent can be shipped in via exemplary rail cars 60b which are connected to a silo 60a via pipe 62 and blower fan 62a. In turn, the reagent is conveyed to silo 60 via pipe 61 and blower fan 61a.
  • the dry solid reagent is transported via conduit 59a to wetting unit 70 supplied with spray nozzles 30a for spraying, for example, water 40 (1) to wet the dry solid reagent (e.g., the source of lime or an equivalent thereof) yielding the alkaline reagent and (2) optionally, to wet any recovered/recycled solids.
  • wetting unit 70 supplied with spray nozzles 30a for spraying, for example, water 40 (1) to wet the dry solid reagent (e.g., the source of lime or an equivalent thereof) yielding the alkaline reagent and (2) optionally, to wet any recovered/recycled solids.
  • conduit 59b directs the alkaline reagent together with any recovered/recycled solids to mill 50.
  • the alkaline reagent and any recovered/recycled solids are pulverized and intimately contacted and mixed with the partially cooled and humidified flue gas 10a introduced into/to the mill through conduit 20a.
  • the mill 50 provides a means for the intimate, preferably turbulent, mixing and contact between the flue gas 10a and the pulverized alkaline reagent produced therein and any recovered/recycled solids.
  • This turbulent mixing and contact together with alkaline reagent pulverization substantially increases the surface area of the alkaline reagent and that of any recovered/recycled solids to further facilitate their reaction with the acid gases entrained in flue gas 10a substantially simultaneously delivered (i.e., to the mill 50) via conduit 20a.
  • the flue gas 10a is cooled from T 2 to T 4 between mill 50 and solids recovery filter 80.
  • Mixing of the cooled and humidified flue gas 10a with the pulverized and/or deagglomerated reactants e.g., alkaline reagent, any recovered/recycled solids, other flue gas components and/or other particulate matter
  • the pulverized and/or deagglomerated reactants e.g., alkaline reagent, any recovered/recycled solids, other flue gas components and/or other particulate matter
  • Turbulent contact and mixing contributed to by mill 50 together with the high flue gas velocity is critical to achieving high removal efficiency at a high flue gas velocity and minimum residence time within mill 50 itself and conveyor duct 20b.
  • the mixing is accomplished by the input of mechanical energy from the exemplary rotating mill 50 which not only provides intimate contact but also creates increased solids surface area for achieving increased reaction rates (e.g., between the alkaline reagent and the acid gases) and improved removal efficiencies (e.g., 95-100%).
  • the residence time from mill 50 to solids recovery filter 80 is sufficient to reduce the one or more acid gas pollutant (including sulfur) levels by about 85% or more, more preferably, by at least 90-95%, and, even more preferably, by about 96-100% based on the total weight of the acid gases contained in the flue gas 10a.
  • An exemplary residence time is from about 0.1 second to about 3 seconds, preferably, from about 0.5 second to about 2.5 seconds, more preferably, from about 0.75 second to about 2.25 seconds, and, even more preferably, from about 1 to about 1.5 - 2 seconds. These aforementioned residence times can be adjusted upwards or downwards based upon the velocity of the flue gas, the volume of the flue gas to be processed, the level of acid gases contained in the flue gas, the surface area of the alkaline reagent and any recovered/recycled solids and the removal efficiency desired or required.
  • the alkaline reagent and any recovered/recycled solids should be deagglomerated to a particle size sufficient to permit an acid removal efficiency of at least 85%, 90%, 91%, 92%, 93%, 94%, 95%, 96%, 97%, 98%, 99% or 100%, respectively.
  • the average particle size of lime or hydrated lime in mill 50 is typically less than about 150 micrometers, preferably less than about 100 micrometers, more preferably less than about 80 micrometers, and most preferably less than about 74- 75 micrometers.
  • Other preferred particle size ranges include, but are not limited to, less than or equal to 10, 20, 30, 40, 50, 60, 60, 70, 80 and 90 micrometers, respectively.
  • the acid gas pollutant(s) entrained in the cooled and humidified flue gas 10a reacts with the exemplary alkaline reagent (e.g., lime or hydrated lime) and any recovered/recycled solids to yield a treated flue gas 10b mixed with solids.
  • the exemplary alkaline reagent e.g., lime or hydrated lime
  • the chemical reactions between the SO 2 and the hydrated lime are exemplified by reactions (I) and (II) previously noted herein.
  • the SO 2 forms reaction products including CaSO 3 together with CaSO 4 and H 2 O. Thereby, the amount of SO 2 pollutants can be reduced to acceptable levels.
  • fly ash is produced.
  • the fly ash which is a natural-by-product of coal combustion, may also react with the SO 2 entrained in the flue gas.
  • the greater the amount of reactive alkaline fly ash present (e.g., inherently and naturally produced by coal combustion) in the flue gas the smaller the amount of the alkaline reagent and any recovered/recycled solids (e.g., desulfurizing agent) that needs to be added to mill 50 to reduce the SO 2 concentration in the flue gas 10a to acceptable levels.
  • Table I indicates that for desulfurizing a flue gas volume of 1,079,914 acfm, an exemplary 135,044/hr of water (275.2 GPM) sprayed from about 50 pressure nozzles over a time of about 2.1 seconds into conduit 20 having a straight length of about 100 feet and a diameter of about 20 feet will result in lowering the flue gas temperature from 325 °F (T,) to 170°F (T 2 ).
  • T, 325 °F
  • T 2 170°F
  • the SO 2 concentration in the flue gas can be reduced from 2,798 ppm to 56 ppm, a 98% desulfurization efficiency (i.e., removal efficiency).
  • the amount of hydrated lime that should be used according to Table I is 0.00033 lb per acfm of flue gas to be processed when the inlet load of SO 2 is 2800 ppm from combustion of 4.5 weight % S coal at 40 % excess air.
  • the weight of the alkaline reagent will range from 5 % of the total solids including recovered/recycled solids to 100 % of the total solids with no recovered/recycled solids, depending upon the weight of recovered/recycled solids used to satisfy the water/mass/chemical balance.
  • reaction products e.g., Ca SO 4 « H 2 O
  • fly ash unreacted alkaline reagent (e.g., lime, hydrated lime and/or any recovered/recycled solids) and any other pollutants and particulate matter entrained therein
  • unreacted alkaline reagent e.g., lime, hydrated lime and/or any recovered/recycled solids
  • any other pollutants and particulate matter entrained therein are induced via a blower 100 via conduit 20 b into an exemplary optional solids recovery .filter 80. See Figure 1.
  • the solids recovery filter 80 is utilized to separate cleaned flue gas entrained in mixture 10b to remove solids including any particulate matter present therein such as fly ash, solid reaction products, excess solid alkaline reagent and any other particulate matter that may be entrained therein.
  • Solids recovery filter 80 is optionally equipped with one or more bag filters 90, which are well known.
  • solids recovery filter 80 is equipped with rotary air locks 80a and 80b.
  • Other solids recovery filters suitable for use with the invention include but are not limited to one or more of a cyclone, an electrostatic precipitator, or other solids filtering equipment or means.
  • the particulate matter entrained in mixture 10b is separated by one or more filters 90.
  • the bag filter material 90 is equipped with pores small enough to permit cleaned flue gas to pass therethrough into conduit 20c towards blower 100, while preventing substantially all the solids including particulate matter entrained in the mixture 10b from passing into conduit 20c.
  • the cleaned flue gas mixture passes through the solids recovery filter 80 to yield filtered and cleaned flue gas 10c which is directed into conduit 20c by blower 100 and ultimately to stack 110.
  • the cleaned and filtered flue gas 10c is released via stack 110 typically into the ambient atmosphere.
  • the particulate matter trapped by solids recovery filter 80 is directed down screw conveyors 28, conduits 25a and 25 and optionally recycled and combined with dry alkaline reagent from silo 60.
  • separation between solids including any particulate matter intended to be recycled to mill 50 and particulate matter to be collected and disposed of as waste 120 can be accomplished by the use of a diverter 25b connected to lines 25a and 26. With regard to any unwanted solids collected by solids recovery filter 80, these solids are preferably directed by diverter 25b down conduit 26 to an exemplary optional spraydeduster 27. Therein, additional water or other suitable fluid is sprayed via spray nozzles 30b onto the unwanted solids to yield waste ready for disposal. Waste 120 for disposal is collected in a suitable container and properly disposed.
  • each temperature T,, T 2 , T 3 , and T 4 is measured by one or more temperature sensors appropriately positioned (not shown) together with the apparatus of Figure 1.
  • the measured temperatures are preferably indicated and recorded.
  • Temperature sensors for T 2 and T 4 are set point controlled via PID feedback loops connected to the system control.
  • the exemplary apparatus of Figure 1 is preferably also equipped with weight monitors 200 and 210 which are preferably also feedback loop controlled.
  • one or more humidity sensors, acid gas sensors, mass flow sensors and the like well known to those of ordinary skill can be appropriately placed to maximize automation and/or acid gas removal efficiency.

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Analytical Chemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Biomedical Technology (AREA)
  • Environmental & Geological Engineering (AREA)
  • Treating Waste Gases (AREA)

Abstract

L'invention concerne un procédé et un appareil d'élimination d'un ou de plusieurs polluants contenus dans les gaz de fumée. Le procédé consiste à refroidir et à humidifier partiellement les gaz de fumée simultanément à une pulvérisation, un contact et un mélange de réactif alcalin avec ceux-ci, suivis d'une étape de filtration afin d'éliminer les solides contenant de la matière particulaire entraînée dans les gaz de fumée, avant la libération des gaz de fumée épurés et filtrés dans l'air ambiant. L'appareil comprend (1) un constituant destiné à refroidir et à humidifier partiellement les gaz de fumée relié à (2) un constituant destiné à pulvériser un réactif alcalin et à mettre en contact, à mélanger et à faire réagir le réactif alcalin pulvérisé avec les gaz de fumée partiellement refroidis et humidifiés, pour réduire le niveau des polluants gazeux acides contenus dans ceux-ci, et relié à la fois (3) à un constituant destiné à préparer le réactif alcalin et (4) à un constituant destiné à séparer les solides contenant de la matière particulaire des gaz de fumée ayant préalablement réagi avec le réactif alcalin. Dans un mode de réalisation préféré, au moins une partie des solides séparés contenant la matière particulaire est récupérée ou recyclée avec le réactif alcalin. Les solides non recyclés sont rejetés en tant que déchets et les gaz de fumée traités/épurés essentiellement sans solides sont libérés dans l'air ambiant.
PCT/US1999/016518 1998-07-24 1999-07-22 Procede et appareil de recuperation de gaz acides de gaz de fumee WO2000004983A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU52215/99A AU5221599A (en) 1998-07-24 1999-07-22 Process and apparatus for recovery of acid gases from flue gas

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US12207798A 1998-07-24 1998-07-24
US09/122,077 1998-07-24

Publications (1)

Publication Number Publication Date
WO2000004983A1 true WO2000004983A1 (fr) 2000-02-03

Family

ID=22400460

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1999/016518 WO2000004983A1 (fr) 1998-07-24 1999-07-22 Procede et appareil de recuperation de gaz acides de gaz de fumee

Country Status (2)

Country Link
AU (1) AU5221599A (fr)
WO (1) WO2000004983A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2883772A1 (fr) * 2005-03-30 2006-10-06 Lab Sa Sa Procede et installation d'epuration de fumees contenant des polluants acides
EP2011558A1 (fr) * 2007-05-16 2009-01-07 Babcock Noell GmbH Installation et procédé de retrait de substances toxiques de gaz d'échappement

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2910537A1 (de) * 1979-03-17 1980-09-18 Steinmueller Gmbh L & C Verfahren zur regenerierung von trockenen und feinkoernigen rueckstaenden aus abgasreinigungssystemen
DE3311100A1 (de) * 1983-03-26 1984-09-27 Wolf Dr.-Ing. 7573 Sinzheim Schulteß Neues verfahren zur gasreinigung - akitvierungssorption
JPS6456122A (en) * 1987-08-24 1989-03-03 Kubota Ltd Treatment of waste incineration furnace gas
DE4338928A1 (de) * 1993-11-15 1995-05-18 Kloeckner Humboldt Deutz Ag Verfahren und Vorrichtung zur Entfernung von Schadstoffen aus einem Gasstrom
WO1997048652A1 (fr) * 1996-06-18 1997-12-24 Fls Miljø A/S Systeme de regulation de la temperature des fumees et de la tension d'alimentation du precipitateur electrostatique dans une cimenterie

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2910537A1 (de) * 1979-03-17 1980-09-18 Steinmueller Gmbh L & C Verfahren zur regenerierung von trockenen und feinkoernigen rueckstaenden aus abgasreinigungssystemen
DE3311100A1 (de) * 1983-03-26 1984-09-27 Wolf Dr.-Ing. 7573 Sinzheim Schulteß Neues verfahren zur gasreinigung - akitvierungssorption
JPS6456122A (en) * 1987-08-24 1989-03-03 Kubota Ltd Treatment of waste incineration furnace gas
DE4338928A1 (de) * 1993-11-15 1995-05-18 Kloeckner Humboldt Deutz Ag Verfahren und Vorrichtung zur Entfernung von Schadstoffen aus einem Gasstrom
WO1997048652A1 (fr) * 1996-06-18 1997-12-24 Fls Miljø A/S Systeme de regulation de la temperature des fumees et de la tension d'alimentation du precipitateur electrostatique dans une cimenterie

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 13, no. 249 9 June 1989 (1989-06-09) *

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2883772A1 (fr) * 2005-03-30 2006-10-06 Lab Sa Sa Procede et installation d'epuration de fumees contenant des polluants acides
EP1716910A2 (fr) * 2005-03-30 2006-11-02 Lab Sa Procédé et installation d'épuration de fumées contenant des polluants acides
EP1716910A3 (fr) * 2005-03-30 2007-12-19 Lab Sa Procédé et installation d'épuration de fumées contenant des polluants acides
EP2011558A1 (fr) * 2007-05-16 2009-01-07 Babcock Noell GmbH Installation et procédé de retrait de substances toxiques de gaz d'échappement

Also Published As

Publication number Publication date
AU5221599A (en) 2000-02-14

Similar Documents

Publication Publication Date Title
US5595713A (en) Hydrogen peroxide for flue gas desulfurization
KR101929558B1 (ko) 폐수를 증발시키고 산성 가스 배출물을 감소시키는 장치 및 방법
EP2295128B1 (fr) Mélangeur pour humidifier une poussière de particules
KR0143304B1 (ko) 건조 흡수제/시약 주입 및 습식 스크러빙에 의한 so2와 so3의 조절 방법 및 조절 시스템
EP0828550B1 (fr) Lavage de gaz d'echappement et systeme de recuperation de chaleur perdue
EP0518606A1 (fr) Procédé et appareillage pour la minimalisation de libération de composés toxiques à l'environnement lors de l'incinération de déchets
CA1217033A (fr) Depollution des gaz de cheminee
KR20170124106A (ko) 폐수를 증발시키고 산성 가스 배출을 감소시키기 위한 장치 및 방법
US4795619A (en) Removal of acid gases in dry scrubbing of hot gases
US8383073B2 (en) Method and apparatus for controlling acid gas emissions from cement plants
EP0446295B1 (fr) Procede et appareil pour eliminer a sec des matieres polluantes se trouvant dans des courants gazeux
US4324770A (en) Process for dry scrubbing of flue gas
KR20160062707A (ko) 습식 연도 가스 탈황 폐수로부터 가스 배출을 감소시키기 위한 시스템 및 방법
RU2698835C2 (ru) Способ и устройство для частичного удаления загрязнений из технологического газового потока
US6749820B2 (en) Chloride/sulfate removal system
EP0862939B1 (fr) Procédé pour le traitement de gaz de fumée
EP0605041B1 (fr) Dispositif et procédé de destruction thermique de substances acides dans les gaz de fumées
WO2000004983A1 (fr) Procede et appareil de recuperation de gaz acides de gaz de fumee
Kroll et al. Application of dry flue gas scrubbing to hazardous waste incineration
CA1168026A (fr) Methode et dispositif de captage a sec des cendres volantes de cheminees
EP0095459A1 (fr) Procede et systeme d'epuration a sec de gaz de fumee.
AU545580B2 (en) Process and system for dry scrubbing of flue gas
PL141220B1 (en) Method of removing gaseous and aerosolic impurities from a stream of gases
Doğu et al. Removal of SO 2 with Lime Slurry in a Spray Dryer
MXPA98001386A (en) Procedure and system to treat hum gas

Legal Events

Date Code Title Description
AK Designated states

Kind code of ref document: A1

Designated state(s): AE AL AM AT AU AZ BA BB BG BR BY CA CH CN CU CZ DE DK EE ES FI GB GD GE GH GM HR HU ID IL IN IS JP KE KG KP KR KZ LC LK LR LS LT LU LV MD MG MK MN MW MX NO NZ PL PT RO RU SD SE SG SI SK SL TJ TM TR TT UA UG US UZ VN YU ZA ZW

AL Designated countries for regional patents

Kind code of ref document: A1

Designated state(s): GH GM KE LS MW SD SL SZ UG ZW AM AZ BY KG KZ MD RU TJ TM AT BE CH CY DE DK ES FI FR GB GR IE IT LU MC NL PT SE BF BJ CF CG CI CM GA GN GW ML MR NE SN TD TG

121 Ep: the epo has been informed by wipo that ep was designated in this application
REG Reference to national code

Ref country code: DE

Ref legal event code: 8642

122 Ep: pct application non-entry in european phase