US3887336A

US3887336A - Incineration systems and methods

Info

Publication number: US3887336A
Application number: US354167A
Authority: US
Inventors: Bruce R Hutchinson; Bruce H Hunter; Robert H Brooks
Original assignee: Bruce R Hutchinson; Bruce H Hunter; Robert H Brooks
Current assignee: HARFORD SYSTEMS Inc ABERDEEN MD A CORP OF
Priority date: 1971-03-18
Filing date: 1973-04-25
Publication date: 1975-06-03
Anticipated expiration: 1992-06-03

Abstract

Apparatus and control techniques for coupling afterburnercentrifugal separator devices to existing incinerators. By means of exercising control over incinerator exhaust stack draft and afterburner temperature, complete oxidation and particulate separation can be achieved in an afterburner unit which may be coupled to an existing incinerator. The invention further encompasses automatic safety features including provision of a bypass for incinerator effluents in the case of any failures in the afterburner system.

Description

United States Patent Hutchinson et al. June 3, 1975 [54] INCINERATION SYSTEMS AND METHODS 3,472,498 10/1969 Price (it ill 23/277 C X 3 67,399 3 1971 Alt t l. [76] Inventors Bruce numbing)", 25 Creswiew 3 258 482 4i1972 new??? 23 277 c Dr., Bloomfield, Conn. 06804; Bruce H. Hunter, 53 Oak Rd., Longmeadow, Mass. 01 106; Robert Primary Examiner-Morris O. Wolk H. Brooks, 239 Auburn Rd. West Assistant Examiner-Michael S. Marcus Hartford, Conn. 06l 19 [22] Filed: Apr. 25, 1973 [57] ABSTRACT [21] Appl. No.: 354,167

Related Us. Application Data Apparatus and control techniques for coupl ng H afterburner-centrifugal separator devices to existing [62] DlVlSlOn of Ser. No. 125,752, Mar 1971- incinerators. By means of exercising control over incinerator exhaust stack draft and afterburner tempera- [52] Cl 23/277 C; 23/2773; 110/8 A ture, complete oxidation and particulate separation hit. can be achieved in an afterburner i which y be [58] Flew of Search 23/277 277 coupled to an existing incinerator. The invention fur- 1 10/8 A:l1O A; 431/5, 8, 9, 12 ther encompasses automatic safety features including provision of a bypass for incinerator cffluents in the [56} References C'ted case of any failures in the afterburner system.

UNITED STATES PATENTS 3,456,603 7/1969 Studler 23/277 C X 8 Claims, 8 Drawing Figures PATENTEU 3 SHEET INCINERATION SYSTEMS AND METHODS This is a division of application Ser. No. 125.752, filed Mar. 18. 1971.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to air pollution control. More specifically, this invention is directed to apparatus for insuring complete combustion of waste materials which are to be eliminated through burning and to the removal of all particulate material entrained in gases exhausted from a combustion chamber. Accordingly, the general objects of the present invention are to provide novel and improved methods and apparatus of such character.

2. Description of the Prior Art While not limited thereto in its utility, the present invention has been found to be particularly well suited for use as an accessory to existing, substandard incineration devices. Considering, for example, the existing situation in many urban areas, one of the major causes of air pollution is the existence and use of conventional incinerators which are employed to burn trash. garbage and the like, within a building. These existing incineration devices are manufactured and installed prior to the recent enactment of municipal ordinances regulating the emission of particulate matter and combustion gases into the atmosphere. Thus, in many populated areas, ordinances have been enacted to prohibit the discharge of odor-bearing fumes, smoke, soot and the like and such ordinances, when effectively enforced, render the use of existing incinerators unlawful.

It has long been known that the efflux from an incinerator can be controlled to a safe and acceptable level by insuring complete oxidation of the efflux and removal of all particulate matter therefrom. To this end, it has often been suggested that existing incinerators should be upgraded through the addition of afterburner structure thereto. Space limitations have, however, often prevented the requisite modification. In addition, presently available afterburners have one or more serious deficiencies from both an operational and a safety standpoint. With regard to these deficiencies, it should be sufficient to state that the operational characteris tics of both the incinerator and afterburner, particularly cyclonic reactor type afterburners, requires that pressures and temperatures within both the existing exhaust stack and the afterburner structure be maintained within well-defined limits. Failure to observe these criteria may result in a fire hazard and/or sucking of air into or discharge of smoke through the charging doors in the incinerator stack as well as incomplete combustion and failure to remove all particulate matter at the afterburner.

To summarize the state of the art, the performance of existing incinerators cannot be upgraded to meet present air quality standards merely by the addition of the prior art afterburner systems at some point downstream of the main incinerator chamber.

SUMMARY OF THE INVENTION The present invention overcomes the above discussed and numerous other disadvantages and deficiencies of the prior art by providing novel and improved afterburner systems and control techniques. These improvements enable use of the invention in the upgrading ofexisting incineration devices so that these devices exceed the air quality standards set by anti-pollution legislation.

In achieving the above general objects, the present invention provides a combination afterburner and centrifugal separator which is designed and controlled in such a manner that complete oxidation of the effluents from an incinerator will occur and substantially all entrained particulate matter will be separated out of an incinerator exhaust gas stream. The afterburner system of the present invention includes control means for maintaining the requisite draft in the incinerator exhaust stack. The present invention also provides for maintenance of the temperature in the afterburner at a sufficiently high level to insure complete combustion.

An additional feature of this invention is the provision of bypass control means whereby incinerator effluents will be vented to the atmosphere in the event of any failure in the afterburner system and wherein afterburning action may be effected manually or instituted automatically upon ignition of a charge in the incinerator. The present invention further provides an afterburner system which may be installed either adjacent the existing incinerator, in the typical basement location, or on a building roof and coupled into the existing incinerator exhaust stack.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention may be better understood and its numerous objects and advantages will become apparent to those skilled in the art by reference to the accompanying drawing wherein like reference numerals refer to like elements in the several figures and in which:

FIG. 1 is a schematic representation of a first embodiment of the present invention, the embodiment of FIG. 1 depicting a roof top of FIG. 2 is a cross-sectional, side elevation view of a preferred afterburner design in accordance with the present invention;

FIG. 3 is a cross-sectional top view, taken along line 3-3, of the afterburner of FIG. 2;

FIG. 4 is a schematic representation of the control circuitry for the afterburner system of FIG. 1;

FIG. 5 is a cross-sectional, side elevation view of a modification which may be employed with the embodiment of FIG. 1; 4

FIG. 6 is a schematic representation of a second embodiment of the present invention. FIG. 6 representing installation of the afterburner adjacent the existing incinerator;

FIG. 7 is a cross-sectional view of an embodiment of an afterburner exhaust stack for use with the invention; and

FIG. 8 is a view, taken along line 8-8, of the stack of FIG. 7.

DESCRIPTION OF THE PREFERRED EMBODIMENTS As previously noted, while not limited in its utility thereto, the present invention is particularly well suited for use in the upgrading of existing incineration equipment. FIG. 1 depicts a first embodiment of the invention in the environment of a rooftop installation. As is often the case, space limitations may prohibit the installation of afterburner structure adjacent to the existing incinerator. In such cases, the invention may be installed on the roof of the building housing the existing incinerator. In FIG. 1, the building roof is indicated at 10, the existing incinerator at 12 and the incinerator exhaust stack at 14. Stack 14 will typically have one or more bin-type charging doors, such as door 16, positioned along its length and the building occupants will deposit material to be incinerated directly onto the hearth or grate of the main combustion chamber of incinerator 12 via charging doors 16 and stack 14. Doors 16 may be provided with thermally or electrically energized interlocks whereby the charging of additional material into incinerator 12 will be prevented when combustion is taking place.

Installation of the present invention at the rooftop level requires that certain modifications be made to stack 14. The first of these modifications is the breaching of the stack as indicated at 18. A second modification comprises the capping of the stack 14. In FIG. 1 this is accomplished by use of a heat-fused door 20 installed at the top of stack 14. Door 20 is normally held in the closed position as shown via a suitable latching mechanism. An increase in the temperature within stack 14 above a predetermined level will result in the melting of a fuze link 22 thereby permitting the door 20 to open. Thus, melting of link 22 due to an overtemperature condition in stack 14 will cause the door 20 to open under the influence of spring 26.

Stack 14 is also modified to the extent that a pair of

sensors

28 and 30 are installed therein. Sensor 28 monitors the temperature within stack 14 for the purposes to be described below. Sensor 30 is pressure responsive and monitors the pressure in stack 14. Pressure sensor 30 will typically be installed in the vicinity of or above the uppermost of the charging doors 16. The function of sensor 30 will also be described below.

The afterburner device is indicated generally at 32 mounted above roof 10 on a supporting platform 34. A preferred embodiment of afterburner 32 is shown in FIGS. 2 and 3 and will be described in detail below. Combustion is promoted in the afterburner 32 by burner 36 which has fuel supplied thereto from a pressurized fuel source, not shown, via a fuel supply system which includes a modulating control valve 38. Air is supplied to burner 36 by a blower 40 and the existence of a supply of pressurized air from blower 40 is monitored by a pressure responsive sensor 42 mounted in the conduit 44 which connects blower 40 with burner 36. A flame monitor 46 is provided for insuring that the pilot in burner 36 does not become extinguished. The function of sensors 42 and 46 will be described in greater detail below in connection with the description of FIG. 4.

Exhaust gases from afterburner 32 are delivered to the atmosphere via an exhaust stack 48 A temperature responsive sensor 50 is mounted in stack 48 for the purpose to be described below.

Communication between afterburner 32 and the breach 18 in the wall of stack 14 is via conduit 52, blower 54 and conduit 56. A damper mechanism 58 is disposed in conduit 56 for controlling the draft in stack 14. The position of damper 58 is controlled via a motor 60 and suitable linkages 61 in response to the pressure monitored by sensor 30 mounted in stack 14; the control circuitry being shown in detail in FIG. 4.

An emergency bypass flue 62 communicates with conduit 52. A damper mechanism 64 is disposed in flue 52. When afterburner 32 is operating, damper 64 will be maintained in the closed position as shown through the action of a control mechanism 66. Mechanism 66 may be a spring return damper motor actuator such as, for example, Type MA-l8 availabe from Penn Controls, Inc. of Goshen, Ind. The damper 64 is biased in the open direction by the spring in mechanism 66 and, should there be a power or mechanical failure which would prevent the operation of blower 54, damper 64 will be automatically opened by unwinding of the spring. The control of damper 64, which is partly under the influence of a pressure sensor 68 mounted in conduit 56 downstream of blower 54, will be described in greater detail in the course of the discussion of FIG. 4.

Before describing operation of the system of FIG. 1, the afterburner 32 as shown in FIGS. 2 and 3 will be described. In the interest of facilitating understanding of the invention, the various sensors and the burner system have been omitted from FIGS. 2 and 3. The afterburner includes a combustion chamber 70 which is defined in part by a lining of refractory material 72 disposed within but separated from a metal housing or vessel 74. In cross-section, chamber 70 is of circular shape as shown. The space between lining 72 and vessel 74 defines a collection chamber 76 for the purposes to be described below. Communication between chamber 70 and burner 36 is via opening 78 which extends through the refractory lining and the wall of vessel 74; the walls of opening 78 being lined with refractory material. The burner 36 fits into opening 78 and injects a flame jet into chamber 70 and partly tangentially to the wall of the chamber. This flame jet intersects and turbulently mixes with the incoming incinerator effluent stream; the burner 36 being provided with a divergent discharge nozzle whereby the flame envelopes the incinerator exhaust products to insure complete oxidation.

Communication between combustion chamber 70 and inlet conduit 56 is via an opening 80 which is also lined with refractory material. As may best be seen from FIG. 3, the opening 80 is tapered so as to define a two-dimensional convergent nozzle 82 which discharges tangentially into chamber 70 at the bottom of the chamber. The nozzle 82 is designed, taking into consideration the capacity of blower 54 and the dimensions of chamber 70, such that the gas discharge into chamber 70 will reach sufficient velocity so as to make at least three complete swirls about the chamber as the gas passes from the bottom of the top thereof.

Considering again FIG. 2, it is to be noted that the afterburner combustion chamber 70 is sized to achieve the requisite residence time. That is, the afterburner must have sufficient volumetric capacity to maintain the incinerator efflux in the flame provided by burner 36 an adequate time to insure complete combustion. The determination of sufficient volumetric capacity is, in part, related to the amounts of material to be burned in the incinerator 12 over a preselected period of time. The size of the orifice 84 through which the combustion products exit from chamber 70 into stack 48 is an additional critical afterburner design parameter. From FIG. 2 it may be seen that orifice 84 has a reduced diameter when compared to the diameter of chamber 70. Tests have shown that the diameter of orifice 84 should be in the range of 50-60% of the diameter of chamber 70 with a 1:2 ratio being preferred in the interest of separating out the maximum percentage of particu- Iates. In the interest of enhancing separation efficiency,

the orifice 84 is in part defined by a downwardly and inwardly sloped portion 88 of the top wall of the afterburner. Wall portion 88 aids in directing the comparatively heavy particulate matter entrained in the swirling gases, and remaining after the combustion in chamber 70, outwardly through an annular discharge port 90 and into the collection chamber 76 between the refractory lining 72 and vessel 74. Discharge port 90 is thus defined by the top of the lining 72 and top wall portion 88. The angle defined by wall portion 88 at the entrance to annular discharge port 90 is preferably approximately 45.

It is also to be noted that the inner walls of stack 48 downstream of orifice 84 define a divergent nozzle 85. Incorporation of a divergent nozzle within stack 48 is in the interest of reducing the velocity of the gases exiting from the afterburner thereby reducing the noise level associated with afterburner operation.

Returning to a consideration of collection chamber 76, a plurality of swirl break-up vanes 92 are provided in the chamber in the interest of causing settling of the particulate matter to the bottom of the collection chamber. The comparatively heavy particles will be swirling when they enter chamber 76 through port 90 and, upon impinging upon a vane 92, the fly ash will fall to the bottom of chamber 76 from which it may be automatically or manually removed via one or more clean'out doors such as door 94.

With reference now to FIG. 4, an electrical schematic ofthe control circuitry portion of the present invention is shown. It is believed that the control embodiment of FIG. 4 may best be understood from an operational description thereof. First, it is to be noted that the afterburner controls will be synchronized with the incinerator controls and such features as manual start switches, fuse panels and warning lights will be located at or near the control panel for the incinerator 12. Operation of the afterburner system will typically be instituted manually either separately from or simultaneously with the start of the ignition sequence for the incinerator. However, the afterburner control system is provided with an automatic start feature which will institute afterburner action automatically after firing of v the incinerator. It is also to to be noted that preheating of the afterburner is to be desired since the afterburner performs more efficiently when hot and thus will function better when preheated prior to the delivery of exhaust gases thereto from incinerator 12.

As noted, operation of the afterburner system may be instituted either manually or automatically. Afterburner start is accomplished by a pair of parallel connected, normally open switches. The first or primary one of these switches is a timer switch 100 which will be manually closed to initiate a sequence which starts with the preheating of the afterburner. Switch 100 will typically have multiple contacts whereby it may also be used to control ignition of the incinerator a predetermined period after the start of the afterburner. Switch 100 is typically preset so as to automatically open after a preselected time period of, for example, 15 minutes. The temperature sensor 28 may include a conventional bimetallic switch. The bimetallic switch in sensor 28 will be closed in response to an increase in temperature within stack 14 commensurate with ignition ofa charge in incinerator 12. Accordingly, after the manual ignition sequence is started with the closing of timer switch 100, if there has been a firing in incinerator 12 sensorswitch 28 will keep the afterburner in the on condition. In the manner to be described in more detail below, closing of either timer switch or the bimetallic temperature sensor-switch 28 will cause the start up of the afterburner.

To briefly recapitulate, a circuit is completed between a power source, indicated at 106, and the controls for the afterburner with the closing of either manually activated timer switch 100 or through the action of the temperature sensor 28. The closing of either of the parallel connected switch contacts will cause the delivery of power to the drive motor 40M for blower 40. The closing of the contacts of either of devices 100 or 28 also effectively connects a first terminal of source 106 to a flame safety control circuit, indicated generally at 108, via conductor 110. Additional inputs to flame safety control 108 are provided by a burner air switch, comprising pressure sensor 42, and the flame scanner 46. Pressure sensor 42 may include a diaphragm type pressure responsive switch which monitors the pressure differential between atmosphere and the interior of duct 44. Sensor 46 may be a conventional ultraviolet flame detector of the type well known in the art.

It is to be understood that control 108 has been shown schematically and that in practice the control will be a commercially available unit such as, for example, a model UVM-lD Flame Safeguard Control available from Electronics Corporation of America, Cambridge, Mass. Control 108 provides, via a plurality of output terminals, for the delivery of power to control circuitry for burner 38. That is, output terminals of control 108 are connected to the pilot solenoid 112 and, via an internal delay circuit 114, to the ignition control solenoid 116 of burner 36. An additional output terminal of control 108 is connected to the solenoid 118 of the main fuel shut-off valve for burner 36. It is to be noted that the main fuel valve, which has not been shown in FIG. 1 in the interest of facilitating understanding of the invention, will be located downstream of modulating valve 38. A further output terminal of control 108 is connected to the drive motor 54M for the main blower 54 located in the duct between stack 14 and the afterburner 32.

Continuing with the operational description, energization of blower motor 40M will, except in cases where there has been a mechanical failure at blower 40, deliver pressurized air to burner 36. Air flow is monitored by the normally open switch of burner air pressure sensor 42 and the availability of pressurized air for the burner will result in the closing of the switch. When the sensor-switch 42 closes the pilot fuel valve solenoid 112 will be energized thereby opening the pilot valve and resulting in the delivery of fuel to the pilot for burner 36. The closing of sensor-switch 42 will also result in the energization of the igniter solenoid 116 via time delay 114. In practice, the ignition will usually be via a spark and there will typically be a 5 second delay on the first start attempt in each ignition sequence with succeeding start ups being instantaneous. When ignition is achieved, flame scanner 46 will provide an output signal which operates, via detector circuitry 120, to close the contacts of a further solenoid operated switch 122. The flame scanner detector circuitry and associated relays are known in the art and form a portion of the commercially available control 108. The closing of switch 122 results in the delivery of power to the solenoid 118 of the main fuel shut-off valve and the burner 38 will thus be rendered operative. The closing of switch 122 also results in the completion of the circuit between power source 106 and drive motor 54M of blower 54.

Further control over the operation of burner 36 is achieved via modulation of valve 38. The purpose of valve 38 is to maintain the afterburner operating tem perature within predetermined limits commensurate with complete oxidation of the effluent from incinerator 12. The control of the valve 38 is achieved via temperature sensor 50 which, as noted above, has a temperature responsive element positioned in the afterburner exhaust stack 48. In one embodiment of the invention, temperature sensor 50 comprised a bimetallic actuator rod and a pair of'single pole, double throw switches. Of these two switches, a first or low temperature limit switch is normally closed while the second or upper temperature limit switch is normally open. The switches control the application of power to a reversible gear motor 124 which is mechanically coupled to the throttling mechanism in valve 38. When the afterburner temperature is within the proper range, both switches will be open thus establishing a dead-band for actuator-motor 124. In the aforementioned embodiment, sensor 50 comprised a model F2C control available from Burling Instrument Company, Chatham, NJ.

The automatic draft control circuitry for operating damper 58 is also connected across source 106 and in parallel with the control for burner fuel supply modulating valve 38. The automatic draft control comprises the pressure sensor 30 mounted in stack 14 and the drive means 60 for damper 58. Pressure sensor 30 will include normally open switch means; which may for example be of the double pole, double throw diaphragm actuated type; which senses the pressure differential between atmosphere and the interior of stack 14 in the vicinity of the uppermost charging door. For proper operation of the incineration system; that is, to insure sufficient draft so that the tire in the incinerator is not choked and to prevent smoke from being forced out through the charging doors or air sucked in therethrough; it is essential that a neutral or slightly negative pressure be maintained in stack 14 in the vicinity of the uppermost of doors 16. Pressure sensor 30 monitors stack pressure and causes the energization of the drive means for damper 58, which may comprise a gear motor 60, in the proper direction to increase ordecrease the draft as necessary to maintain the proper stack pressure. Thus, the damper 58 will throttle the flow to the afterburner under low fire conditions at the incinerator. However, if the damper 58 closes too much, the stack pressure will increase and sensor 30 will operate to cause motor 60 to be driven in the opposite direction to open the damper.

The control for the emergency bypass flue damper 64 comprises a normally closed, solenoid operated switch 126 and the pressure sensor 68. Since the contacts of switch 126 are normally closed, the actuator motor 66 for damper 64 is normally connected across source 106 and the damper will be maintained in the closed position by the normally energized motor 66. As noted above, the motor 66 will be a spring return damper motor actuator which will unwind" should. the delivcry of power to the motor be interrupted. The unwinding of damper motor 66 will result in the opening of damper 64.

The solenoid of normally closed switch 126 will be energized, thus opening its contacts, by the closing of either of parallel connected timer switch 100 or switch contacts controlled by temperature sensor 28. Thus, the contacts of switch 126 will be closed and the bypass damper 64 accordingly held closed by motor 66, under the control of switch 126, until the afterburner has been ordered into operation by v the closing of the contacts of either of switch means 100 or 28. When the afterburner ignition sequence is started, and the solenoid of switch 126 energized thereby interrupting power to motor 55, the damper 64 will begin to open. As the afterburner ignition sequence proceeds, blower 54 will begin operation thereby causing the closing of the normally open contacts of pressure sensor 68. The closing of the switch associated with sensor 68 will reenergize motor 66 thus returning damper 64 to the full closed position. The cracking of damper 64 with each afterburner start is a safety measure incorporated in the interest of insuring against a bearing freeze or other mechanical failure in either motor 66 or damper 64.

Should there be a failure of any kind during afterburner operation, the pressure responsive switch 68 will open thereby deenergizing motor 66 and permit ting the bypass damper 64 to go to the full open position. Restated, should there be an electrical power failure, any type of mechanical failure at either of blowers 54 and 40 or a flame out in the afterburner 32, blower 54 will cease operation causing the opening of pressure sensor switch 68 and the unwinding of motor 66. A deliberate shut down of the afterburner, however, will deenergize the solenoid of switch 126 thereby permitting the switch contacts to return to the normally closed position and maintaining motor 66 in the energized condition even though pressure responsive sensor-switch 68 will open.

To summarize the embodiment of the present invention as depicted in FIGS. l-4, mechanically the system consists of an afterburner which functions as both a combustion chamber and centrifugal separator. Ignition in the afterburner chamber 70 is promoted by burner 36 and separation of fly ash and other particulate matter occurs by spinning the burning effluents and centrifugally separating particulates into the chamber 76 while the clean exhaust gases exit through the orifice 84 and stack 48. The effluents are drawn from the source, comprising incinerator 12 and stack 14, through the breaching 18 by blower 54. An emergency bypass flue 62 is provided for the escape of effluent gases in the event of any operational failure in the afterburner system.

From the standpoint of control, the blower 40 for the fuel fired burner 36 of afterburner 32 will be started either manually, through the initiation of a start sequence, or automatically upon the sensing of heat in stack 14. In response to the start up of blower 40, the burner 36 is turned on and, in response to the sensing of flame, the main blower 54 is started. Simultaneously with the start of the afterburner ignition sequence, the damper 64 in the bypass flue 62 is opened slightly and thereafter returned to the full closed position. In the event of flame failure at the afterburner. electrical failure anywhere in the system or a mechanical failure at either of blowers 40 and 54, the system is automatically closed down and the bypass duct damper 64 opened.

During normal operation, proper pressure is maintained in the stack 14 by the draft control damper 58 via its associated stack mounted pressure sensor 30 and control 60. The effluent cleansing action of the afterburner is enhanced by maintaining afterburner temperatures within a predetermined range through the use of the fuel modulating valve 38. The control over valve 38 is effected through monitoring the temperature in afterburner exhaust stack 48 with sensor 50 and the afterburner operating temperature is held at a sufficiently high level to insure complete oxidation of all combustible incinerator effluents.

FIG. depicts a modification of the present invention which may be employed in cases where there is an air infiltration problem with respect to stack 14. With respect to air infiltration, in cases where the stack 14 is quite high the operation of blower 54 may result in the drawing of air through the stack walls and charging doors rather than drawing flue gas from the incinerator. To overcome this problem, a conduit 200, which is typically comprised of aluminized steel, will be inserted in stack 14 in order to divide the stack into a chargin portion 201 and an exhaust portion 202; portion 202 being internally of conduit 200. With the afterburner installed on the building roof, the conduit 200 is capped off at the level of the top of breaching 18 thus defining a flow path 202 extending from adjacent the incinerator exit orifice to the rooftop mounted conduit 52.

In accordance with the embodiment of FIG. 5, the stack 14 is further modified, at a position adjacent the bottom termination of conduit 200, for the installation of a damper 204. The damper 204, when in the closed position shown, provides a substantially airtight seal which prevents incinerator effluents from entering the charging portion 201 of stack 14. Suitable control circuitry is provided to insure that damper 204 will be closed prior to ignition of a charge in incinerator 12 whereby all of the effluents from the incinerator will pass up passage 202 to the afterburner. The damper 204 is operated through a suitable device train by a motor 206.

The

sensors

28 and 30 will, in the FIG. 5 embodiment be installed in the vicinity of breach l8 and will be exposed to the pressure and temperature within passage 202.

It is to be noted that the heat fused door will usually be maintained in the system when the embodiment of FIG. 5 is employed. Retention of door 20 provides protection in the case of a jam and flare up in charging portion 201 of the flue.

Fl. 6 depicts the present invention installed adjacent the exiting incinerator 12 rather than at the rooftop level. Structurally and operationally the embodiment as shown in FIG. 6 is similar to that of FIG. 1. That is. basement installation of the afterburner requires modification of stack 14, to prevent direct venting of effluent from incinerator 12, coupled with a breaching which enables the effluents to be drawn off and directed to the afterburner. As shown in FIG. 6, the breaching is accomplished directly into the wall of the incinerator 12. However, the transfer duct 52 could be connected into stack 14 just above the incinerator. In the embodiment of FIG. 6, the stack 14 is employed to exhaust the clean gases exiting from afterburner 32. This requires that the incinerator exhaust stack 48 be coupled back into stack 14 at a position above the breaching and, or course, that the heat fused door 20 which caps stack 14 in the rooftop installation be omitted.

In order to normally isolate the incinerator exit orifree from the afterburner discharge stack, a damper mechanism 220 will be installed in stack 14 at a convenient location between the top of incinerator 12 and the connection between afterburner stack 48 and stack 14. The mechanism 220 may take the form of a guillotine door which, in the manner to be described below, serves the dual functions of capping the incinerator and providing an emergency bypass flue.

As noted, operation of the embodiment of FIG. 6 is similar to that of FIG. 1 with initiation of afterburning action being commanded by either timer switch or temperature sensor 28. The proper draft is maintained in duct 52 by means of damper 58 and its associated control mechanism with the pressure sensor operating to insure enough draft so that the fire in the incinerator is not choked. It is to be noted that, as shown in FIG. 6, the damper 58 is located on the incinerator side of blower 54. This upstream location of the damper is actually preferred in both basement and rooftop installations although either position may be employed depending upon space and other considerations. The control over motor 60 of damper 58 is identical to that described above in connection with the discussion of FIG. 4 and pressure sensor 30 will typically be mounted in conduit 52 adjacent breach 18. g

The incineration system of both of the above discussed embodiments is disclosed as being a flue fed device wherein the waste material to be burned is deposited onto the hearth or grate of incinerator 12 through charging doors 16 in stack 14. The damper mechanism 220, which will be in the closed position shown when combustion is taking place in incinerator 12, comprises an angled sliding blade 222 which is moved mechanically by actuator 224 via arm 226. The blade 222 passes through the wall of stack 14 as shown and provides a substantially airtight seal for closing off stack 14. As noted, the damper mechanism 220 will be in the closed position when burning is taking place. When the damper is controlled to be closed only when incineration is occurring, it is considered desirable to provide for interlocks on the charging doors 16 which prevents the deposit of refuse during times when the damper mechanism 220 is closed. Installation of such interlocks would be in the interest of preventing damage to the damper mechanism 220 by impingement thereof of unusually heavy pieces of refuse and also in the interest of safety since the exhaust from the afterburner will be hotter than the normal exhaust from incinerator 12. Alternatively. interlocks may be provided which will prevent the use of the charging doors only when incineration is taking place and the damper may be then be normally closed. In the normally closed damper installation, the charge for the incineration may be stacked up on top of the blade 222 with suitable sensors being installed in stack 14 to indicate when the damper should be withdrawn to the open position and the charge deposited on the incinerator hearth.

The control of the actuator 224 for the damper 220 may include the bypass damper control as discussed above. The control may, however. be modified so that the damper 220 will be retracted except when the afterburner is in operation.

FIGS. 7 and 8 disclose a further embodiment of the present invention which is in the nature of a modification to the afterburner exhaust stack 48. The embodiment of FIGS. 7 and 8 may be used with the systems of either of FIGS. 1 or 6 but would more typically be associated with the FIG. 6 system. In accordance with the stack modification, an outer jacket 230, typically a steel cylinder, is provided. Jacket 230 will be coaxial with the refractory lining 232 in exhaust stack 48 whereby an air passage of chamber 233 is defined between the refractory lining and the jacket. The refractory lining is provided with openings at a plurality of levels; these openings providing communication be tween the passage 233 and the interior of the exhaust stack. These rows of openings are indicated at 234, 236 and 238 and define jets or nozzles which discharge air into the exhaust stack. As may be seen from FIG. 8, the jets discharge into the interior of the afterburner exhaust stack in a direction tangential to the stack wall. It is particularly to be noted that the jets discharge in opposite directions at successive levels the enhancing the turbulent mixing. As can be seen from FIG. 7, the size of the jets in the rows increases in the direction of gas flow through the exhaust stack.

The addition of auxiliary air in exhaust stack 48 is in the interest of both promoting combustion and cooling the exhaust gases. The graduation in size of the jets insures against quenching the flame emanating from the afterburner at the lower end of the stack.

As shown in FIG. 7, the air for the rows of

auxiliary jets

234, 236 and 238 is supplied by an auxiliary blower 240 which would typically be operated in tandem by the controls for the main blower 54. Alternatively, the air supplied for the auxiliary jets can be furnished by the main blower. As will be obvious to those skilled in the art, the number of rows of auxiliary air jets may be varied with three rows ofjets being shown in FIG. 7 for purposes of illustration only.

While preferred embodiments have been shown and described, various modifications may be made thereto without departing from the spirit and scope of the present invention. Thus, while the present invention has been described in the environment of an accessary for existing incinerator devices, it will be noted that the invention has utility in the control of the pollutants emanating from many sources. By way of examples, the gaseous effluents from smoke houses, paint shops, printing shops and the like may be directed to the present invention for purposes of complete combustion and particulate removal. Accordingly it is to be understood that the present invention has been described by way of illustration and not limitation.

What is claimed is:

1. An afterburner device comprising:

a combustion chamber having a generally cylindrically shaped wall, said combustion chamber being open at its upper end;

a particulate collection chamber disposed about the exterior of said combustion chamber;

means for tangentially injecting a gaseous effluent into said combustion chamber adjacent the bottom thereof; means for injecting a flame into the path of the gaseous effluent in said combustion chamber;

temperature responsive means for controlling said flame injecting means whereby a temperature sufficiently high to insure complete combustion of the effluent is maintained in the said combustion chamber; and

afterburner exhaust stack means supported concentrically of and generally above the open upper end of said combustion chamber, said exhaust stack means having a lower end, said lower end of said exhaust stack means defining an outlet orifice for gases from said combustion chamber, the lower end of said exhaust stack means which defines said outlet orifice bein of smaller diameter than said combustion chamber, the wall of said combustion chamber cooperating with said lower end of said exhaust stack means to define an annular discharge port adjacent the open upper end of said combustion chamber, said annular discharge port providing communication between said combustion chamber and said collection chamber.

2. The apparatus of claim 1, wherein said effluent injecting means comprises a convergent nozzle.

3. The apparatus of claim 2 wherein the diameter of said orifice defined by the lower end of said exhaust stack means is in the range of 50-60% of the diameter of said combustion chamber.

4. The apparatus of claim 1 wherein said exhaust stack means comprises:

an exhaust stack having a circular cross-section;

a plurality of rows of air injection jets passing through the wall of said exhaust stack; and

means for delivering pressurized air to said jets.

5. The apparatus of claim 4 wherein said jets discharge into said stack in a direction tangential to the stack internal wall.

6. The apparatus of claim 5 wherein said jets in each of said plurality of rows increase in size in the direction of exhaust gas flow through said stack.

7. The apparatus of claim 6 wherein said effluent injecting means comprises a convergent nozzle.

8. The apparatus of claim 7 wherein the diameter of said orifice defined by the lower end of said exhaust stack means is in the range of 50-60% of the diameter of said combustion chamber.

Claims

1. AN AFTERBURNER DEVICE COMPRISING: A COMBUSTION CHAMBER HAVING A GENERALLY CYLINDRICALLY SHAPED WALL, SAID COMBUSTION CHAMBER BEING OPEN AT ITS UPPER END; A PARTICULATE COLLECTION CHAMBER DISPOSED ABOUT THE EXTERIOR OF SAID COMBUSTION CHAMBER; MEANS FOR TANGENTIALLY INJECTING A GASEOUS EFFLUENT INTO SAID COMBUSTION CHAMBER ADJACENT THE BOTTOM THEREOF; MEANS FOR INJECTING A FLAME INTO THE PATH OF THE GASEOUS EFFLUENT IN SAID COMBUSTION CHAMBER; TEMPERATURE RESPONSIVE MEANS FOR CONTROLLING SAID FLAME INJECTING MEANS WHEREBY A TEMPERATURE SUFFICIENTLY HIGH TO INSURE COMPLETE COMBUSTION OF THE EFFLUENT IS MAINTAINED IN SAID COMBUSTION CHAMBER; AND AFTERBURN EXHAUST STACK MEANS SUPPORTED CONCENTRICALLY OF AND GENERALLY ABOVE THE OPEN UPPER END OF SAID COMBUSTION CHAMBER, SAID EXHAUST STACK MEANS HAVING A LOWER END, SAID LOWER END OF SAID EXHAUST STACK MEANS DEFINING AN OUTLET ORIFICE FOR GASES FROM SAID COMBUSTION CHAMBER, THE LOWER END OF SAID EXHAUST STACK MEANS WHICH DEFINES SAID OUTLET ORIFICE BEIN OF SMALLER DIAMETER THAN SAID COMBUSTION CHAMBER, THE WALL OF SAID COMBUSTION CHAMBER COOPERATING WITH SAID LOWER END OF SAID EXHAUST STACK MEANS TO DEFINE AN ANNULAR DISCHARGE PORT ADJACENT TO OPEN UPPER END OF SAID COMBUSTION CHAMBER, SAID ANNULAR DISCHARGE PORT PROVIDING COMMUNICATION BETWEEN SAID COMBUSTION CHAMBER AND SAID COLLECTION CHAMBER.

1. An afterburner device comprising: a combustion chamber having a generally cylindrically shaped wall, said combustion chamber being open at its upper end; a particulate collection chamber disposed about the exterior of said combustion chamber; means for tangentially injecting a gaseous effluent into said combustion chamber adjacent the bottom thereof; means for injecting a flame into the path of the gaseous effluent in said combustion chamber; temperature responsive means for controlling said flame injecting means whereby a temperature sufficiently high to insure complete combustion of the effluent is maintained in the said combustion chamber; and afterburner exhaust stack means supported concentrically of and generally above the open upper end of said combustion chamber, said exhaust stack means having a lower end, said lower end of said exhaust stack means defining an outlet orifice for gases from said combustion chamber, the lower end of said exhaust stack means which defines said outlet orifice bein of smaller diameter than said combustion chamber, the wall of said combustion chamber cooperating with said lower end of said exhaust stack means to define an annular discharge port adjacent the open upper end of said combustion chamber, said annular discharge port providing communication between said combustion chamber and said collection chamber.

4. The apparatus of claim 1 wherein said exhaust stack means comprises: an exhaust stack having a circular cross-section; a plurality of rows of air injection jets passing through the wall of said exhaust stack; and means for delivering pressurized air to said jets.