US3905312A

US3905312A - Process and apparatus for incinerating waste materials

Info

Publication number: US3905312A
Application number: US468028A
Authority: US
Inventors: Howard H Nichols
Original assignee: Individual
Current assignee: Individual
Priority date: 1974-05-08
Filing date: 1974-05-08
Publication date: 1975-09-16
Anticipated expiration: 1992-09-16

Abstract

Waste materials to be incinerated are charged at a controlled rate through movable hinged doors that open into the upper end portion of a cyclone-type furnace. The furnace has a conical configuration and a refractory lining enclosed within a heat resistant casing to thereby form an interior incinerating chamber. The upper end portion of the furnace chamber includes an inlet opening that communicates with a combustion chamber from which preheated combustion air is tangentially introduced into the furnace chamber through the inlet opening to establish intimate admixing of the waste materials and combustion gases. An oxygen analyzer having a sensor located in the furnace chamber continuously monitors the oxygen content of the furnace atmosphere. An air valve that controls the flow of air to the combustion chamber is operatively associated with the oxygen analyzer and responds to variations in the furnace oxygen content by supplying the proper amount of air to the furnace chamber to insure complete combustion of the waste materials. Complete combustion of the waste materials in the furnace produces a gaseous effluent stream that is conveyed through an outlet opening in the lower end portion of the furnace chamber to an outlet duct where the effluent stream is cooled and particulate matter removed prior to discharge to the atmosphere.

Description

United States Patent 1191 Nichols 1451 Sept. 16, 1975 PROCESS AND APPARATUS FOR INCINERATING WASTE MATERIALS [76] Inventor: Howard H. Nichols, 100 Bryn Mawr Ct., Apt. 8-419, Pittsburgh, Pa. 15221 22 Filed: May 8, 1974 21 Appl. No.: 468,028

[52] US. Cl. 110/8 R; 110/8 A; 110/28 F; 110/ 175 [51] Im. (:l. F236 5/12; F23M 7/00 58 Field of Search 110 7 R, 8 R, 8 C, 8 A, 110/18 R, 18 C, 28 F, 173, 175; 236/15 E [56] References Cited UNITED STATES PATENTS 3,074,644 1/1963 Geniesse 236/15 3,173,389 3/1965 Catcs, Jr. 6t al. 110/173 3,396,681 8/1968 Hubbard 110 28 3,597,345 8 1971 Hickam et a]. 236/15 x 3,604,375 9 1971 Bruns et al 110/7 3,640,233 2/1972 Reiner et 31.. 110/173 3,716,001 2/1973 Potasek 110/8 3,722,433 3 1973 Kramer 110/7 3,792,670 2/1974 DlNOZZl.... 110 8 3,805,714 4 1974 Sharpe... 110/7 3,818,846 6/1974 Reese 110/8 Primary ExaminerKenneth W. Sprague Attorney, Agent, or Firm-Stanley J. Price, Jr.

[ 57 ABSTRACT Waste materials to be incinerated are charged at a controlled rate through movable hinged doors that open into the upper end portion of a cyclone-type furnace. The furnace has a conical configuration and a refractory lining enclosed within a heat resistant casing to thereby form an interior incinerating chamber. The upper end portion of the furnace chamber includes an inlet opening that communicates with a combustion chamber from which preheated combustion air is tangentially introduced into the furnace chamber through the inlet opening to establish intimate admixing of the waste materials and combustion gases. An oxygen analyzer having a sensor located in the furnace chamber continuously monitors the oxygen content of the furnace atmosphere. An air valve that controls the flow of air to the combustion chamber is operatively associated with the oxygen analyzer and responds to variations in the furnace oxygen content by supplying the proper amount of air to the furnace chamber to insure complete combustion of the waste materials. Complete combustion of the waste materials in the furnace produces a gaseous effluent stream that is conveyed through an outlet opening in the lower end portion of the furnace chamber to an outlet duct where the effluent stream is cooled and particulate matter removed prior to discharge to the atmosphere.

11 Claims, 3 Drawing Figures PATENTH: w 1v 6 ma 3,905,131 2 SHEET 1 [IF 2 PROCESS AND APPARATUS FOR INCINERATING WASTE MATERIALS BACKGROUND OF THE INVENTION l. Field of the Invention This invention relates to a process and apparatus for incinerating waste materials, and more particularly to the incineration of waste materials in a furnace in which the waste materials and preheated combustion air are intimately admixed at controlled rates and in the proper proportion to insure complete combustion of the waste materials.

2. Description of the Prior Art Apparatus and process for disposing of municipal and industrial waste materials in a manner which is not detrimental to the atmosphere as required by pollution control laws are well known in the art. For example, US. Pat. No. 3,604,375 illustrates and describes an incineration process which employs two furnaces for the combustion of waste materials. The first furnace incompletely burns the refuse to produce a combustible gaseous exhaust stream that is intimately admixed in an unfired afterbumer with a. noncombustible gaseous stream produced by complete combustion in the second furnace. The heat produced by the noncombustible stream is then utilized for the spontaneous ignition and complete combustion of the unburned materials in the combustible stream. The afterbumer output is then processed to protect against the discharge of pollutants to the atmosphere.

US. Pat. No. 3,602,161 discloses a smokeless trash incinerator that includes a lower trash-receiving chamber communicating with an upper smoke-incinerating chamber. Air is selectively supplied to regions of both chambers in accordance with the temperatures maintained therein for incinerating the trash charged through a door in the lower chamber. A burner located in the upper chamber and supplied with an air duct incinerates incompletely burned gases exhausted from the lower chamber.

An apparatus for feeding rubbish from a receiving hopper into an incinerator is described in US. Pat. No. 3,680,719. The charging end of the incinerator is pro vided with a pivotally mounted door sealing the charging passageway into the incinerator. A fluid actuated piston cylinder assembly operates the door between an open and closed position to control the feeding of the rubbish from a storage bin into the incinerator.

The primary factors to consider in the incineration of municipal and industrial wastes are burning the waste materials at an elevated temperature and admixing the waste materials and combustion air in the proper proportions to insure complete combustion of the combustible materials and oxidation of the noncombustibles to a final oxide state. Preferably, the burning takes place at temperatures in excess of 2,500F. With temperatures in this range substantially all of the materials are transformed to a gaseous effluent stream with entrained particulate matter and fume. Only a small percentage of the materials, such as certain metals, chemically combine with oxygen to produce slag which is suitably withdrawn from the furnace or metallic oxide particles which are removed in a scrubber section. To reach the above elevated temperature in the furnace, preheated combustion air is supplied to the furnace by violently introducing the preheated combustion air into the furnace. A turbulent cyclonic action is established,

and the waste materials and gases are intimately admixed to insure complete combustion of the unburned materials. Also, the waste materials and gases must be i in the proper proportion to provide sufficient oxygen in the furnace atmosphere for complete combustion.

There is need to provide a process and apparatus for disposing of waste materials by incineration in a high temperature furnace into which the waste materials are charged at a controlled rate and in proportion to the flow of combustion air to thereby insure complete combustion and oxidation of all materials charged and the melting of the noncombustibles to form slag.

SUMMARY OF THE INVENTION In accordance with the present invention there is provided a process and apparatus for incinerating waste materials that includes a furnace having an internal incinerating chamber. The furnace chamber includes an inlet opening provided in the upper end portion of the chamber for receiving preheated combustion air from a source. The furnace chamber has an outlet opening in the lower end portion thereof for discharging a gaseous effluent stream from the furnace chamber produced by the complete combustion of the waste materials and preheated combustion air in the furnace. A plurality of charging doors seal the upper end portion of the furnace chamber. An actuating mechanism opens and closes the doors to permit charging of the waste materials into the chamber at a preselected rate. A first control device monitors the oxygen content of the preheated combustion air supplied to the furnace chamber. A second control device regulates the flow of preheated combustion air through the inlet opening to the furnace chamber in response to the oxygen requirements in the chamber as monitored by the first control device to thereby ensure complete combustion of the waste materials.

The combustion air is preheated in a combustion chamber by a fluid fuel burner to a temperature of approximately 600F. An air-fuel control device maintains the proper admixing of fluid fuel and air in the burner to insure complete combustion of the fuel. The air for heating is fed through a first air duct to the combustion chamber by an air blower. In the preferred embodiment of the invention the second control device includes an air valve which regulates the flow of air from the air blower through a second air duct communicating with the combustion chamber. In this manner the flow of preheated air to the furance chamber is se lectively controlled. The first control device, such as an oxygen analyzer, monitors the oxygen content in the furnace chamber. If the input of waste materials into the furnace chamber exceeds the required input for a predetermined flowrate of preheated air to insure complete combustion of the waste materials, then the oxygen analyzer actuates the air valve to increase the supply of preheated air to the furnace.

An additional feature of this invention includes operation of the actuating mechanism to reduce the input of waste materials charged to the furnace when a maximum supply of preheated air is fed to the furnace. The condition of maximum feed of preheated air to the furnace occurs when the air valve is in position to provide maximum flow of air through the second air duct into the combustion chamber. Accordingly, the oxygen analyzer will indicate that the furnace atmosphere contains the minimum oxygen content to sustain complete combustion of the waste materials at the prevailing charge rate and at the maximum flow of preheated air to the furnace. To retard the charge rate into the furnace and thereby maintain complete combustion of the waste materials, the actuating mechanism reduces the input area into the'furnace by moving the doors to a preselected position from the maximum open position. In this fashion, the amount of waste materials fed into the furnace is reduced so that sufficient air can be supplied to provide complete combustion of the waste materials.

Accordingly, the principal object of the present invention is to provide a process and apparatus for incinerating waste materials that includes a furnace into which waste materials and preheated combustion air are fed at controlled rates resulting in intimate admix ing of the waste materials and combustion air to completely incinerate the combustible materials and oxidize the noncombustible materials producing a relatively pollution-free effluent stream, slag and usable production of combustion.

Another object of the present invention is to provide a process and apparatus for incinerating waste materials in which the oxygen in air content of the furnace atmosphere is continuously monitored to provide the op timum commingling of waste materials and combustion air and thereby ensure complete combustion of the wastes with substantially no emission of pollutants detrimental to the atmosphere.

A further object of the present invention is to provide a process and apparatus for incinerating waste materials in a cyclone-type furnace having charging doors operable to control the input rate of waste materials charged into the furnace.

Still another object of the present invention is to provide a process and apparatus for incinerating waste materials in a furnace in which the waste materials are fed at a predetermined rate into the furnace for a predetermined flow of combustion air thereto to completely destroy the waste materials.

These and other objects and advantages of this invention will be more completely disclosed and described in the following specification, the accompanying drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a pictorial representation of the apparatus for incinerating waste materials.

FIG. 2 is a vertical sectional view of the furnace for burning the waste materials, illustrating the turbulent action of the preheated combustion air introduced into the furnace.

FIG. 3 is a schematic representation of the control apparatus for monitoring and regulating the combustion of the waste materials in the furnace.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, and particularly FIGS. 1 and 2, there is illustrated apparatus for incinerating waste materials that is generally designated by the numeral 10. The term waste materials is used herein to designate both municipal and industrial wastes having no recyclable value in liquid, semi-liquid and solid combustible form. The waste materials vary in heat value, and the liquid waste materials may have a high or low viscosity. The waste disposal and incineration apparatus includes a furnace 12, preferably a cyclonetype furnace, capable of burning waste materials at elevated temperatures up to 2,900F.

The furnace 12 receives the waste materials from a waste collecting and transporting vehicle 14 that charges the materials through a plurality of movable hinged doors 16 that open into the chamber of the furnace. An air preheater unit generally designated by the numeral 18 supplies air heated to a preferred temperature of about 600F. through an inlet conduit 20 into the furnace 12. The preheater unit 18 includes a combustion chamber 22 that is suitably connected to the inlet conduit 20. The air fed to the combustion chamber 22 is heated by a fluid fuel burner 24 having a fuel feed line 26 for the passage of either liquid fuel or natural gas into the fuel burner 24. Air duct 30 supplies air to the burner 24 as required for combustion of the fuel therein.

Control valves

32 and 34 provided in

conduits

28 and 30 control the flow of air to the combustion chamber 22 and the burner 24 respectively. An air blower 36 operated by a motor forces air under pressure through the primary air duct 38 into the

secondary air ducts

28 and 30.

A control panel 40 is positioned adjacent the air preheater unit 18 for monitoring the temperature in the furnace 12, the air-fuel ratio in the burner 24 and the oxygen content in the furnace 12, in a manner hereinafter described. Positioned at an elevation below the control deck and connected to the rear end portion in the furnace 12 is a horizontal outlet duct 42 that conveys the exhaust gases from the furnace 12 to a vertical stack 44 open to the atmosphere. A damper 46 provided in the outlet duct 42 is operated by a motor 48 to maintain a slightly negative pressure at the furnace charge doors l6 and thereby control the flow of cold air into the furnace 12.

To accommodate the combustion of liquid waste materials, suitable storage tanks (not shown) may be located in the immediate vicinity of the furnace 12. The liquid waste materials will be stored after analysis according to viscosity and heat value to insure the proper setting of the combustion controls for the complete combustion and oxidation of all the liquid materials. Once the liquid wastes have been classified and separated according to viscosity and heat value, the liquid may be introduced by piping into the furnace 12. The liquid wastes having a heating value in excess of 100,000 B.t.u,/gal. are acceptable for use as fuel in heating the combustion air in the combustion chamber 22, whereas, liquid wastes having a heating value as low as 7,500 B.t.u./gal. may be charged directly into the furnace 12 for combustion. Furthermore, the heat value of liquids are also adaptable for controlling the temperature of the furnace 12 to insure the complete combustion of the solid waste material input to the furnace 12.

The furnace 12 for incinerating the waste materials, as illustrated in detail in FIG. 2, has the configuration of a frustrum of a right circular cone and in a specific embodiment has an inside diameter of approximately 40 feet at the upper end portion and 10 feet at the lower end portion. The conical furnace 12 is supported at an angle inclined from the vertical adjacent to and below the unloading dock 50 from where the disposal vehicles 14 unload the waste materials onto the charging doors 16. The furnace 12 includes a high temperature resistant, refractory lining 52 that is encased within an outer heat resistant metal casing 54 to thereby define an interior incineration chamber 56. The chamber 56 includes a circular upper end portion 58 having an air inlet 60 that is connected to the air inlet conduit of the preheater unit 18. The air inlet 60 is positioned tangentially relative to the inner surface of the chamber wall. In this manner, a cyclonic flow is established within the chamber56 for turbulently admixing the waste materials with the combustion gases introduced through the air inlet 60. The furnace 12 also includes a lower end portion 62 having an aperture 64 leading to the outlet duct 42. The outlet duct 42 also is lined with a refractory material that is encased by a heat resistant metal.

The open upper portion of the furnace 12 is sealed by the plurality of movable hinged doors 16. A hydraulic actuating device generally designated by the numeral 66 is operable upon actuation to move the doors 16 from a closed position to an open position, as illustrated in FIG. 2, to thereby control the charge rate of the waste materials into the chamber 56. Each of the doors 16 includes a lower section 17 hinged to an upper section 19 that is integrally connected at its upper end portion to the circular portion of the furnace 12. The lower end portion of the upper section 19 includes a transverse pivot connection 68 that is, in turn, linked by a bracket 21 to the upper end portion of the lower section 17. With this arrangement, the lower section 17 is capable of moving angularly relative to the upper section 19 and open the furnace 12 to receive the waste materials discharged from the dump truck 14.

The actuating device 66 includes a hydraulic motor 67, shown in FIG. 1, that is secured to the upper section 19 and has a drive shaft 69 connected to one end of the actuator rod 71. The opposite end of the actuator rod 71 is suitably linked to the intermediate portion of the lower door section 17. Operation of the motor 67 longitudinally moves the rod 71 to angularly move the lower door section 17 relative to the upper door section 19 about the pivot connection 68. Thus, the furnace operator can regulate the charge rate of the waste materials into the chamber 56 by moving the lower end portion of the lower door section 17 a preselected distance away from the vertical wall 73 of furnace 12. The waste materials are deposited from the dump truck 14 onto the surface of the lower door section 17 and are charged into the furnace chamber 56 as the door section 17 pivots downwardly away from the wall 73 into the chamber 56. In addition, the pivot connection 68 includes an internal chamber 75 through which coolant circulates to protect the door sections 17 and 19 and the connection 68 from the damaging effects of the elevated temperatures produced in the furnace 12.

The preheated air for initiating the combustion of the waste materials is introduced tangentially at high velocity into the chamber 56. Consequently, a cyclonic action is generated within the chamber 56 and picks up the lighter components of the waste materials, such as paper, and suspends these materials in the gaseous atmosphere of the chamber 56. The intimate mixing of the light waste materials and preheated combustion air promotes instantaneous combustion of these materials to thereby provide a high rate of heat liberation and substantial increase in the temperature in upper end portion 58 of the furnace 12. In this manner, temperatures in the range between about 2,800and 2,900F. are produced in the furnace 12. In addition, the temperature in the furnace 12 is also controlled by the amount of fuel and preheated combustion air introduced through the air inlet 60. Preferably, a 15 percent excess of air based on the stoichiometric amount is needed for the complete combustion of the waste materials in the chamber 56.

The tangential injection of preheated air into the chamber 56 produces a centrifugal force which moves the heavier materials outwardly from the center of the chamber toward the wall thereof. In this manner, the heavier solid waste particles experience a longer residence time in the furnace chamber 56 than do the lighter particles to thereby assure complete combustion of the heavier combustible particles.

Generally, metals, glass, ceramics and like materials which constitute the heavier materials in the composition of the refuse processed in accordance with the present invention are noncombustibles. The ferrous metals are removed from the refuse by magnetic separation prior to the charging of the refuse into the furnace chamber 56 so that substantially all the remaining metallic materials present in the charge are nonferrous metals. An analysis of a representative sample of municipal waste indicates only a small percentage amount of nonferrous metals. Since the temperature of the combustion products in the furnace 56 is in the range from about 2,800to about 2,900F. the remaining nonmetallic metals are vaporized.

The following Table I is an analysis of the composition of a representative sample of municipal refuse after magnetic separation of the ferrous metals.

If some magnetic metals should remain in the furnace charge, a great portion thereof will be vaporized and the remaining metals, magnetic and nonmagnetic, together with the other noncombustibles chemically combine with oxygen and are reduced to a stable oxide state in the form of particulate matter or fume which becomes entrained in the gaseous effluent stream. These contaminates are subsequently removed from the effluent stream before the stream passes to the stack 44.

A further product of the oxidation of the noncombustible waste materials includes molten slag and water vapor. The centrifugal action created by the turbulent flow in chamber 56 forces the molten slag into contact with the chamber walls which are at a sufficiently high temperature to maintain the slag in a fluid state. The molten slag isthus confined to the chamber walls and is directed downwardly along the sloping walls of the furnace 12 to the lower end portion 62. From there the slag passes through the aperture 64 and is withdrawn from the refractory lined duct 42 through outlet into a tap that communicates with a conventional slag granulating drum 72, as illustrated in FIG. 3. The slag granulating drum 72 provides rapid cooling of the molten slag and substantially removes the hydrogen sulfide gas from the effluent that is conveyed through the outlet duct 42 to the stack 44. With the above described arrangement, the cyclonic rotation of the combustion air around the circumference of the chamber 56 intimately ing in the scrubber exit effluent is less than 1 gram per cubic foot or 0.2 pounds per 1,000 pounds of exit effluent. Thus, the gaseous effluent stream is emitted from the stack 44 with substantially all the particulate matter admixes the combustion air with the waste materials to removed therefrom. The treated effluent stream disthereby completely burn all the combustible materials charged to the atmosphere then includes relatively and oxidize the noncombustible materials forming pure and uncontaminated products of combustion. The clean products of combustion, water vapor and slag. emissions treated in the above described manner are The noncombustible materials which are not reduced odor-free and contain no pollutants which are detrito slag in the furnace 12 leave the furnace as particul0 mental to the atmosphere. Furthermore, the damper 46 late matter and fume entrained in the gaseous effluent operated by the motor 48 in the outlet duct 42 pro stream. The following Table I1 is a theoretical analysis duces negative pressure in the furnace chamber 56 to of the proportional quantities of the particulate matter insure a constant flow of gaseous effluent from the and fume that pass from the furnace 12 with the effluchamber 56 through the duct 42 to the stack 44. Also, ent, based on percent noncombustible material in 15 by operation of the damper 46 to the flowrate of the the refuse charged. gaseous effluent to the duct 42 is controlled in response TABLE 11 Clay Ceramics, Glass Calcium Alumina Ceramic And (ALQOH) Other Compound Solids Silica Dusts Ash Metals Totals 7: refuse charged 4.63 3.70 5.77 .33 .57 15.0 7r refuse to slag 4.38 .52 3.10 8.0 7: refuse to particulate .13 2.12 1.60 3.85 7r refuse m fume .12 1.06 1.07 .33 57 3.15

The gaseous effluent stream that is emitted from the to the rate or waste materials charged into the furnace furnace 12 through the aperture 64 and the duct 42 is chamber 56. estimated to have the following composition. Referring to FIG. 3, there is schematically illustrated the instrumentation for monitoring and controlling the TABLE [I] combustion of the waste materials in the furnace 12. A thermocouple 74 located in the upper end portion 58 Gas permL percent Dry of the furnace chamber 56 measures the temperature therein and is connected by conduit 76 to a temperagjgggg 3:2; 5;}, 4O ture recorder 78 mounted on the control panel 40. The Carbon Dioxide 2M0 2440 recorder 78 is actuated by the thermocouple 74 to give Sulphur Dimdde an instantaneous reading of the temperature in the fur- Water Vapor 12.39

Totals 10000 00.00 nace 12. The recorder 78 is connected by condu1t 80 to a fuel control valve 82 provided in the fuel feed line 26 that supplies fluid fuel to the burner 24. With this Prior to treating the effluent stream fOI' removal Of arrangement the temperature recorder also fun the Pamculate material and fume, t Stream S Cooled tions as a fuel controller which is responsive to the temby 21 Conven ional he abso g device perature sensed by the thermocouple 74 in the furnace such as a steam generating boiler. The products of 12, combustion may also be cooled by introducing a liquid The recorder 78 compares the furnace temperature spray formed by nozzles positioned in the outlet duct as measured by the thermocouple 74 with a predeter- 42. The temperature of the effluent stream is reduced mined temperature at which the recorder 78 has been by either of these two methods to a temperature of programmed. If the measured furnace temperature about 500F. In addition, the coolant may also have a should vary from the programmed temperature, the composition suitable for neutralizing some of the acids temperature recorder-controller 78 will open or close in the effluent stream. the valve 82, accordingly, to thereby regulate the sup- Following cooling, the effluent stream is introduced ply of fuel fed through the fuel line 26 to the burner 24. into a high energy scrubber (not shown) which re- Thus, the temperature to which the combustion air is moves the particulates and fume by dissolving or enheated in the combustion chamber 22 and fed through training them in water. The scrubber may be selected the inlet duct 20 to the furnace chamber 56 is selecfrom any of the conventionally known scrubbers, such tively controlled. By increasing or decreasing the temas a venturi scrubber, for treating an effluent stream perature of the combustion air, the temperature in the and removing entrained particulate material therefrom. furnace 12 is maintained at a predetermined level be The liquid and agglomerated particulates are thus retween a maximum temperature for periods of maximoved from the effluent stream and discharged to a cooling pond where the particulate material settles and is easily removed for land fill purposes.

Preferably, the amount of particulate matter remainrnum refuse charge and at a minimum temperature for periods of minimum refuse charge.

As the supply of fuel to the burner 24 is controlled for the preheating of the combustion air, the supply of air to the burner 24 required for combustion of the fuel therein is regulated by the fuel-air controller generally designated by the numeral 84. The controller 84 may be selected from any of the commercially available fuel-air controllers, such as a Bailey. The controller 84 includes a measuring device 86 for monitoring the flowrate of the air delivered from blower 36 to the duct 30. The device 86 is connected to a flowrate meter 88 which provides a continuous reading of the flowrate of the air from the blower 36. In response to the amount of fluid fuel supplied to the burner 24, the valve 34 is controlled by a regulator 90. Thus, the air flowrate to the burner 24, as indicated by the meter 88, is automatically controlled by the position of the valve 34 in the duct 30. The regulator 90, in turn, controls the position of the valve 34 to supply the required amount of air for the fuel supplied to the burner 24 and thereby preheat the combustion air to preferably 600F. Depending on the combustion conditions in the furnace 12, the air may be heated to a temperature less than 600F., and certain conditions may require no preheating at all.

In addition to controlling the preheating of the combustion air by the above described arrangement, the heat produced by the furnace 12 is also controlled by the amount of preheated air fed to the furnace 12 from the combustion chamber 22. As stated above, a 15 percent excess of air above the stoichiometric amount for combustion of the waste materials in the furnace 12 is preferred. Accordingly, the amount of air for complete combustion of the refuse charge is dependent upon the rate of feed of the refuse into the furnace 12.

To provide an instantaneous indication of the oxygen content in the furnace atmosphere a conventional oxygen analyzer 92 is connected by conduit 94 to a sensor 93 located in the furnace chamber 56. The readout of the oxygen analyzer 92 provides an indication of the oxygen content of the furnace atmosphere. Any deviation from the oxygen content in the furnace atmosphere required to maintain complete combustion of a given refuse input will be detected by the analyzer 92. An oxygen analyzer suitable for use in the present invention is sold by Thermo-Lab Instruments, Inc. of Pittsburgh, Pa. 15206.

The oxygen requirements in the furnace chamber 56 increase as the oxygen content decreases with an increase in the refuse input. Accordingly, as the oxygen requirements increase with an increase in the refuse input, the analyzer will transmit an electrical impulse through conduit 95 to regulate the position of the control valve 32 in air duct 28. In this manner, the quantity of air supplied from the blower 36 through conduit 28 to the combustion chamber 22 for heating and delivering to furnace 12 is selectively controlled.

The analyzer 92 actuates the control valve 32 to supply a predetermined quantity of air to the combustion chamber 22 for a given refuse input. Preferably, the amount of air fed to the furnace chamber 56 through the air inlet 60 is about 15 percent above the stoichiometric amount for combustion of the refuse input. For a preferred refuse input of 50 tons per hour having a lower heating value of 5,502 B.t.u./lb., 4.74 thousand lbs./hr. of combustion air heated to 600F. is required for complete combustion of the refuse in the furnace 12 at a temperature of about 2,900F. Thus, approximately 4.53 pounds of air is required toincinerate one pound of refuse. For this refuse input and air delivery into the furnace 12, an effluent stream is produced having a heat content of about 554 million B.t.u./hr.

As waste material is continuously charged into the chamber 56, the rate of oxygen in air consumption increases proportionally, requiring the air valve 32 to open wider and permit increased air flow to the combustion chamber 22 and furnace chamber 56. When the analyzer 92 has positioned the valve 32 in a maximum open position, a light will illuminate on the control panel 40 alerting the operator to the condition of maximum air into the furnace 12. Consequently, the

operator must maintain the charge rate constant and monitor the analyzer 92 to insure that the oxygen content of the furnace atmosphere is sufficient to promote complete combustion of the refuse. If the charge rate should reach the level beyond which sufficient combustion air can be delivered to the furnace 12 for complete combustion, the percentage of fume and particulate matter in the effluent stream will increase.

In the event insufficient combustion air is supplied to the furnace chamber 56 for completely burning a given refuse input, the operator can reduce the input rate to the furnace. The charge rate is controlled by decreasing the area of the input opening into the chamber 56 by moving the lower door sections 17 to an intermediate position between the maximum open position, as illustrated in dashed lines in FIG 2, and the closed position. As hereinabove stated, this is accomplished by operation of the hydraulic actuating device 66.

Further in accordance with the invention, an automatic control device may be provided to operatively coordinate the setting of the control valve 32 with the input area to the chamber 56. To this end, the actuating device 66 is responsively connected to the control valve 32 so that the charge rate does not exceed the corresponding combustion air flowrate into the chamber 56 to sustain complete combustion. Thus, when maximum combustion air is supplied to the chamber 56, the actuating device 66 automatically closes the doors 16 to decrease the charge input. The control valve 32 may then maintain maximum flowrate or decrease the flowrate to the combustion chamber 22. If a deficiency in the oxygen content in the furnace atmosphere still exists, the oxygen analyzer 92 will emit a signal to thereby initiate a reduction in the charge input to insure complete combustion of the refuse for the given supply of preheated combustion air.

In addition to the preheated combustion air supplied to the furance chamber 56, cold air enters the chamber with the charge input through the open charge doors 16. The damper 46 located in the outlet duct 42 maintains a negative pressure in the chamber 56. A negative pressure in the chamber 56 insures constant flow of cold air throughthe open charge doors 16 into the chamber 56. Also, a negative furnace pressure serves to keep the dust, odor and spillage generated outside the chamber 56, as a result of the depositing of the waste material onto the doors 16, at a minimum level.

A furnace pressure control device 96 located on the control panel 40 provides the furnace operator with a continuous reading of the air pressure in the furnace chamber 56. The pressure control device 96 receives electrical impulses from a pressure sensor 98 located in the furnace chamber 56. The pressure meter on the control device 96 instantaneously indicates the furnace pressure as measured by the sensor 98. The control device 96 is programmed for a predetermined pressure to be maintained in the chamber 56. Should the actual pressure in the chamber 56 vary from the predetermined pressure, the control device 96 will transmit an electrical signal through conduit 100 to actuate the motor 48 of the damper 46. Thus, the motor 48 will move the damper 46 to a position which will restore the furnace pressure to the predetermined level.

According to the provisions of the patent statutes, 1 have explained the principle, preferred construction and mode of operation of my invention and have illustrated and described what I now consider to represent its best embodiments. However, it should be understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim: 1. Apparatus for incinerating waste materials comprising,

a furnace having an internal incinerating chamber, said furnace chamber includes an inlet opening in the upper end portion thereof for receiving preheated combustion air from a source and an outlet opening in the lower end portion thereof for discharging a gaseous effluent stream from said furnace chamber, a plurality of charging doors sealing the upper end portion of said furnace chamber, actuating means for opening and closing said charging doors to permit the charging of the waste materials into said furnace chamber at a preselected rate, first control means for monitoring the oxygen content of the combustion air in said furnace chamber, and second control means for regulating the flow of the preheated combustion air through said inlet opening to said furnace chamber in response to the oxygen requirements in said furnace chamber as monitored by said first control means to insure complete combustion of the waste materials in said furnace chamber, means for recording the temperature in said furnace chamber, and means for preheating the combustion air introduced into said furnace chamber to a preselected temperature. 2. Apparatus for incinerating waste materials as set forth in claim 1 which includes,

said actuating means operable to maintain a predetermined charge rate of the waste materials into said furnace chamber when the flow of the pre heated combustion air through said second control means reaches a predetermined level. 3. Apparatus for incinerating waste materials as set forth in claim 1 which includes,

a combustion chamber for preheating the combustion air fed to said furnace chamber, conduit means for connecting said combustion chamber to said furnace chamber, valve means for supplying air at a preselected rate to said combustion chamber for preheating, means for heating the air in said combustion chamber to a predetermined temperature, and third control means for actuating said heating means to heat the combustion air in said combustion chamber to a predetermined temperature responsive to the temperature in said furnace chamber to maintain the temperature therein at a predetermined level between a maximum temperature for periods of maximum waste material charge and a minimum temperature for periods of minimum waste material charge in said furnace chamber.

4. Apparatus for incinerating waste materials as set forth in claim 3 which includes,

means for supplying air to said heating means at a controlled rate responsive to the amount of fuel supplied to said heating means to insure the proper mixing of the air and fluid fuel for complete combustion of the fuel to heat the air in said combustion chamber to a preselected temperature.

5. Apparatus for incinerating waste materials as set forth in claim 1 which includes,

means for measuring the atmospheric pressure in said furnace chamber,

an outlet duct communicating with said furnace chamber outlet opening, said outlet duct arranged to convey the gaseous effluent stream from said furnace chamber for particle removal, and I a power operated damper positioned in said outlet duct, said damper actuated by said pressure measuring means to assume a preselected position in said outlet duct for maintaining a predetermined pressure in said furnace chamber.

6. Apparatus for incinerating waste materials as set forth in claim 1 which includes,

said charging doors each having an upper section rigidly secured to said furnace and a lower section pivotally hinged to said upper section,

said actuating means operable to angularly move said lower section about its hinged connection to said upper section to a preselected position between a first position closing the upper end portion of said furnace chamber and a second position opening the upper end portion of said furnace chamber and thereby control the charge rate of the waste materials into said furnace chamber to insure complete combustion of the waste materials therein.

7. Apparatus for incinerating waste materials as set forth in claim 1 in which said first control means includes,

an oxygen analyzer operably connected to said second control means,

said oxygen analyzer having a sensor located in said furnace chamber for measuring the oxygen content therein,

said oxygen analyzer operable to actuate said second control means to supply a predetermined quantity of the preheated combustion air to said furnace chamber to insure complete combustion of a predetermined amount of waste materials charged thereto.

8. Apparatus for incinerating waste materials as set forth in claim 1 in which said second control means includes,

an air valve communicating with said inlet opening and arranged to control the supply of preheated combustion air fed to said furnace chamber at a predetermined flowrate.

9. A process for incinerating waste materials which comprises, I

charging waste materials at a preselected rate into the chamber of a furnace,

10. A process for incinerating waste materials as set forth in claim 9 which includes,

maintaining a predetermined charge rate of waste materials into said furnace chamber in response to a predetermined flowrate of preheated combustion air into said furnace chamber to sustain complete combustion of the waste materials. 11. A process for incinerating waste materials as set forth in claim 9 which includes,

reducing the charge rate of waste materials into said furnace chamber when the oxygen content of the combustion air in said furnace chamber reaches the minimum level to thereby insure complete combustion of the waste materials therein.

Claims

1. Apparatus for incinerating waste materials comprising, a furnace having an internal incinerating chamber, said furnace chamber includes an inlet opening in the upper end portion thereof for receiving preheated combustion air from a source and an outlet opening in the lower end portion thereof for discharging a gaseous effluent stream from said furnace chamber, a plurality of charging doors sealing the upper end portion of said furnace chamber, actuating means for opening and closing said charging doors to permit the charging of the waste materials into said furnace chamber at a preselected rate, first control means for monitoring the oxygen content of the combustion air in said furnace chamber, and second control means for regulating the flow of the preheated combustion air through said inlet opening to said furnace chamber in response to the oxygen requirements in said furnace chamber as monitored by said first control means to insure complete combustion of the waste materials in said furnace chamber, means for recording the temperature in said furnace chamber, and means for preheating the combustion air introduced into said furnace chamber to a preselected temperature.

2. Apparatus for incinerating waste materials as set forth in claim 1 which includes, said actuating means operable to maintain a predetermined charge rate of the waste materials into said furnace chamber when the flow of the preheated combustion air through said second control means reaches a predetermined level.

3. Apparatus for incinerating waste materials as set forth in claim 1 which includes, a combustion chamber for preheating the combustion air fed to said furnace chamber, conduit means for connecting said combustion chamber to said furnace chamber, valve means for supplying air at a preselected rate to said combustion chamber for preheating, means for heating the air in said combustion chamber to a predetermined temperature, and third control means for actuating said heating means to heat the combustion air in said combustion chamber to a predetermined temperature responsive to the temperature in said furnace chamber to maintain the temperature therein at a predetermined level between a maximum temperature for periods of maximum waste material charge and a minimum temperature for periods of minimum waste material charge in said furnace chamber.

4. Apparatus for incinerating waste materials as set forth in claim 3 which includes, means for supplying air to said heating means at a controlled rate responsive to the amount of fuel supplied to said heating means to insure the proper mixing of the air and fluid fuel for complete combustion of the fuel to heat the air in said combustion chamber to a preselected temperature.

5. Apparatus for incinerating waste materials as set forth in claim 1 which includes, means for measuring the atmospheric pressure in said furnace chamber, an outlet duct communicating with said furnace chamber outlet opening, said outlet duct arranged to convey the gaseous effluent stream from said furnace chamber for particle removal, and a power operated damper positioned in said outlet duct, said damper actuated by said pressure measuring means to assume a preselected position in said outlet duct for maintaining a predetermined pressure in said furnace chamber.

6. Apparatus for incinerating waste materials as set forth in claim 1 which includes, said charging doors each having an upper section rigidly secured to said furnace and a lower section pivotally hinged to said upper section, said actuating means operable to angulArly move said lower section about its hinged connection to said upper section to a preselected position between a first position closing the upper end portion of said furnace chamber and a second position opening the upper end portion of said furnace chamber and thereby control the charge rate of the waste materials into said furnace chamber to insure complete combustion of the waste materials therein.

7. Apparatus for incinerating waste materials as set forth in claim 1 in which said first control means includes, an oxygen analyzer operably connected to said second control means, said oxygen analyzer having a sensor located in said furnace chamber for measuring the oxygen content therein, said oxygen analyzer operable to actuate said second control means to supply a predetermined quantity of the preheated combustion air to said furnace chamber to insure complete combustion of a predetermined amount of waste materials charged thereto.

8. Apparatus for incinerating waste materials as set forth in claim 1 in which said second control means includes, an air valve communicating with said inlet opening and arranged to control the supply of preheated combustion air fed to said furnace chamber at a predetermined flowrate.

9. A process for incinerating waste materials which comprises, charging waste materials at a preselected rate into the chamber of a furnace, introducing preheated combustion air from a source into said furnace chamber at a preselected rate of flow, admixing the waste materials and preheated combustion air in said furnace chamber to produce a gaseous effluent stream, monitoring the oxygen content of the combustion air in said furnace chamber, controlling the flow of preheated combustion air to said furnace chamber in response to the oxygen requirements in said furnace chamber to insure complete combustion of the waste materials in said furnace chamber, and withdrawing the gaseous effluent stream from said furnace chamber.

10. A process for incinerating waste materials as set forth in claim 9 which includes, maintaining a predetermined charge rate of waste materials into said furnace chamber in response to a predetermined flowrate of preheated combustion air into said furnace chamber to sustain complete combustion of the waste materials.

11. A process for incinerating waste materials as set forth in claim 9 which includes, reducing the charge rate of waste materials into said furnace chamber when the oxygen content of the combustion air in said furnace chamber reaches the minimum level to thereby insure complete combustion of the waste materials therein.