United States Patent: 3566809

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United States Patent	3,566,809
Carry , et al.	March 2, 1971

INCINERATOR FOR WASTE MATERIAL

Abstract

An incinerator of industrial and commercial type comprising a vertical combustion chamber arranged to receive processed waste material of combustible nature, including trash and garbage, and discharge the same upwardly through the bottom of the chamber for initial combustion by a primary burner surrounding the inlet to the chamber, the exhaust for products of combustion being positioned adjacent the top of the chamber and a horizontal separator being positioned in spaced relationship to the inlet to the exhaust means operable to cool the gases of combustion and also deflect solid material back to the combustion zone, and ash discharge means located in the bottom of the combustion chamber for discharge into a quenching pool having conveyor means to remove the quenched ash upwardly for discharge to suitable disposal means.

Inventors:	Carry; Robert W. (Oradell, NJ), Flemming; Francis J. (Plainfield, NJ), Hindenlang; Arthur W. (Edison, NJ)
Assignee:	Ecology Industries, Inc. (South Plainfield, NJ)
Appl. No.:	04/841,262
Filed:	July 14, 1969

Current U.S. Class: 110/187 ; 110/190; 110/212; 110/216; 110/259

Current International Class: F23G 5/08 (20060101); F23G 5/12 (20060101); F23g 005/12 ()

Field of Search: 110/7,8,16,15,18

References Cited [Referenced By]

U.S. Patent Documents


2242653	May 1941	Maxwell
3163133	December 1964	Montgomery
3200777	August 1965	McIntire
3472185	October 1969	Burden, Jr.
3482533	December 1969	Ankersen

Primary Examiner: Sprague; Kenneth W.

Claims

We claim:

1. An incinerator for completely burning all ignitable portions of waste material delivered thereto and comprising in combination, a vertical circular combustion chamber, waste inlet means positioned substantially centrally of the bottom thereof and directed vertically upward into said chamber, means to direct a primary combustion air stream under pressure to said waste inlet means and also entrain and propel waste material through said inlet means, a primary burner surrounding said inlet means, means to deliver carbonaceous fuel to said primary burner, exhaust means at the top of said chamber to discharge products of complete combustion, a horizontal heat-resistant separator member spaced below said exhaust means and substantially coaxial therewith and the periphery thereof being spaced from the inner surface of said chamber to define an annular passage for products of combustion to said exhaust means, said separator being operable to cause solid particles to be deflected to said annular passage and intensify the combustion thereof, means to induce a flame vortex in the combustion chamber to enhance combustion, ash-receiving means paced radially outward from and arranged around said primary burner and comprising a series of funnel-shaped openings depending downwardly from the bottom of said chamber, and means adapted to feed waste material to said air stream for delivery thereof to said waste inlet means and said burner.

2. The incinerator according to claim 1 further including inlet means intermediately between the top and bottom of said combustion chamber and operable to be connected to a supply of air under pressure to deliver secondary air to said combustion chamber to enhance complete combustion of waste material within said chamber.

3. The incinerator according to claim 2 in which said inlet for secondary air is disposed tangentially with respect to the walls of said combustion chamber and thereby being operable to produce a swirling movement of combustion gases within the combustion zone of said chamber to render the combustion of waste material efficient by retarding the upward movement thereof and provide a vortex which also effects efficiency in the separator.

4. The incinerator according to claim 1 further including an additional burner adjacent the upper portion of said combustion zone and operable to effect secondary combustion in the upper portion of said combustion zone when substantially complete combustion of the consumable ingredients of the waste material introduced into such combustion zone has not been effected by said primary burner.

5. The incinerator according to claim 4 further including a smoke detector adjacent and said exhaust means in the upper portion of said combustion chamber and operable to ignite said secondary burner in response to smoke existing in the upper portion of said combustion zone.

6. The incinerator according to claim 1 further including a heat exchanger in said exhaust means of said chamber, air supply means connected thereto, and a conduit extending from said heat exchanger and communicating with said waste inlet means and operable to introduce warm air thereto to facilitate the combustion of said waste material by said primary burner.

7. The incinerator according to claim 1 further including a quenching pool positioned beneath the bottom of said combustion chamber and operable to receive ash material received from said ash-receiving means and operable to quench the same and provide a seal against the escape of products of combustion.

8. The incinerator according to claim 7 further including conveyor means operable to receive quenched ash material and move the same upwardly from said quenching pool for discharge to disposal means.

9. The incinerator according to claim 8 further including control means operable to regulate the water level in said pool, said control means being adjacent the discharge end of said conveyor means for ready access to regulation thereof.

10. The incinerator according to claim 7 in which said ash-receiving means comprises a plurality of discharge ports arranged in circular pattern around the bottom of said combustion hopper and further including a central hopper device operable commonly to receive discharge from all of said discharge ports, said hopper being positioned within said quenching pool.

11. The incinerator according to claim 10 in which said hopper communicates with the lower end of said ash conveyor means.

Description

BACKGROUND OF THE INVENTION

Disposal of waste material from business establishments, hotels, apartment houses, hospitals, municipalities, and various kinds of industrial plants poses a continual problem in view of what appears to be an ever increasing amount of waste material requiring disposal. Such waste material includes not only trash of multitude of types but also garbage of both wet and dry types. The vast majority of incinerators now in use to dispose of waste material by incineration are very largely inefficient and in the operation thereof, very substantial quantities of contaminants of both gaseous and solid nature are discharged into the atmosphere with resulting pollution of atmospheric air which results in very substantial pulmonary ailments and other irritations to people in the surrounding vicinity as well as the consternation of public officials who have to deal with the problems.

Many attempts have been made to provide efficient types of incinerators which will be relatively free from odor as well as the discharge of gaseous and solid contaminants to the atmosphere. A number of these are relatively complex and require constant attention with the result that the lack of the required attention results in inefficient operation of the systems.

Certain of the prior attempts to produce effective incineration are represented by the following U.S. Pat. Nos. 1,531,766 Trimborn et al. Mar. 31, 1925; 2,242,653 Maxwell May 20, 1941; 3,408,167 Burden, Jr. Oct. 29, 1968

SUMMARY OF THE INVENTION

It is the principal object of the present invention to provide a relatively simple, compact and highly efficient incinerator incorporating certain safeguards and control mechanism which will insure substantially complete combustion of all types of consumable components of waste material by providing a vertical combustion chamber to receive waste material, which has been previously processed to render it capable of being introduced in the form of a stream, which preferably is airborne, to the lower portion of the combustion chamber for initial contact by a primary burner surrounding the waste inlet, said chamber having a separate or in the upper portion thereof in spaced relationship to the discharge means for purposes of cooling the combustion gases prior to discharge and deflecting solid material back to the discharge zone or to ash discharge means in the bottom of the combustion chamber, secondary combustion means also being provided, if needed, in the upper portion of the combustion chamber and regulated by control means responsive to a predetermined temperature and operable to ignite the secondary combustion means to insure complete combustion of all waste material prior to discharge of the products of combustion from the upper portion of the combustion chamber.

It is another object of the invention to provide said separator with water cooling means, preferably around the periphery while moving to the discharge therefor at the upper portion of the incinerator.

It is a further object of the invention to provide ash quenching means preferably comprising a water pool immediately below the bottom of the combustion chamber and operable to receive hot ash material from the combustion chamber and quench the same prior to removal by conveyor means which is directed upwardly and outwardly from the quenching pool, the level of the water in the quenching pool being regulated by suitable control means and also serving as a seal against internal pressure which otherwise might cause escape of noxious gases.

Details of the foregoing objects and of the invention, as well as other objects thereof, are set forth in the following specification and illustrated in the accompanying drawings comprising a part thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical sectional elevation of an exemplary incinerator embodying the principles of the invention as seen on the line 1-1 of FIG. 2;

FIG. 2 is an enlarged transverse sectional view of the lower portion of the combustion chamber of the incinerator as seen on the line 2-2 of FIG. 1;

FIG. 3 is a fragmentary horizontal sectional view of a detail of the secondary air inlet for the combustion chamber as seen on the line 3-3 of FIG. 1;

FIG. 4 is an enlarged vertical sectional view of the primary burner construction and the discharge end of the refuse inlet means which is concentric therewith;

FIG. 5 is a fragmentary horizontal sectional view of a portion of the primary burner as seen on the line 5-5 of FIG. 4; and

FIG. 6 is a diagram illustrating the path of movement of water-cooling means for a separator in the combustion chamber shown in FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

In conjunction with the operation of the incinerator comprising the present invention, it is contemplated that the waste material will have been subjected to appropriate pretreatment for introduction in stream form through a conduit of appropriate diameter in proportion to the size of the combustion zone within the incinerator. For best results, the waste material therefore preferably should be comminuted to acceptable, predetermined maximum size to render the same capable of being introduced by an air current by mechanism described in detail hereinafter.

Referring to FIG. 1, the incinerator unit 10 preferably is supported upon a suitable foundation 12. The foundation is formed from concrete or steel and shaped to contain a pool of water 14 for purposes of quenching the ashes discharged thereto from the combustion chamber of unit 10. Further, such pool provides a seal against internal pressure.

Extending through one wall of the supporting foundation 12 is a refuse inlet conduit 16. Said conduit may comprise conventional industrial pipe or tubing of appropriate diameter. By way of example rather than limitation, if the incinerator has a burning capacity of approximately 1 ton of refuse per hour, it has been found that an inlet conduit having an inner diameter of 8 inches is suitable. As seen from FIG. 1, at a location outside of the foundation 12, the inlet conduit 16 preferably has a preheated air inlet conduit 18 communicating therewith, preferably at an acute angle in a direction to facilitate the passage of refuse through said inlet. Such arrangement enhances the efficiency of combustion of the waste material and preheated air may be obtained effectively from heat transfer means located in the combustion exhaust means in the upper part of the incinerator unit as described in detail hereinafter.

The incinerator unit 10 preferably is circular in cross-sectional configuration and the walls thereof are of a composite nature. They consist of an external metal shell 20, a layer of suitable heat-resistant insulation material 22 immediately within the shell 20, and an inner wall 24 of appropriate refractory material capable of withstanding the relatively high temperatures generated within the incinerator.

The bottom of the incinerator unit 10 has a horizontal metal plate 26 having a preferably central opening therein through which the preferably vertical discharge end 28 of refuse inlet conduit 16 extends. The bottom plate 26 is suitably welded to the lower end of shell 20 and appropriate heavy brackets 30 extend vertically and radially outward from the exterior of the shell 20 and are connected thereto as well as to the radially extending periphery of bottom plate 26. Appropriate holes are formed therein to receive anchor bolts 32 which are set into the concrete foundation 12. Bottom plate 26 also supports a relatively thick, horizontal refractory liner 34 which has an appropriate central opening therein to accommodate the discharge end 28 of conduit 16, the opening being sufficiently large to also accommodate the consuming flame 36 which surrounds the discharge end 28 of the refuse conduit as shown in greater detail in FIG. 4.

Bottom plate 26 also is provided with a circular arrangement of ash-discharge ports 38 and communicating, funnel-shaped openings 40 extend upwardly therefrom through the bottom refractory liner 34 around the periphery thereof and communicate with the discharge ports 38. Particularly from FIG. 1, wherein one of the openings 40 is shown in vertical sectional elevation, it will be seen that the shape of the incinerator unit 10 is frustoconical, having its larger diameter near the top thereof, whereby the inner surface of the refractory liner 24 is at least slightly funnel-shaped and actually forms an effective surface to guide ash material into the various openings 40, by gravity, From there, the material falls through the discharge ports 38 and into ash chutes 42 which extend downward and inwardly from ports 38 for discharge into a common, central hopper 44.

The chutes 42 and hopper 44 are immersed normally within the pool of quenching water 14. The hopper 44 communicates with the lower end of ash conveyor 46 comprising an appropriate watertight casing which extends at an angle through the foundation wall 14 and in watertight communication therewith. An endless conveyor 48 is supported suitably by conventional sprockets adjacent opposite ends of the conveyor casing 46, said conveyor having buckets 50 thereon which, at the upper end of the conveyor discharge into a suitable receptacle 52 which preferably is of substantial capacity and may be of the type arranged to be lifted to the bed of a truck for transportation to a suitable disposal site.

In view of the fact that the top of the hopper 44 is in open communication with the water pool 14, the conveyor casing 46 likewise is filled with water from said pool. Gas pressures within the combustion chamber circulate through chutes 42 and place the liquid under pressure and thereby provide a seal against internal pressure which otherwise might escape to atmosphere. The upper end of the casing 46 communicates with a small laterally extending tank 54 which is open at the side thereof communicating with the adjacent wall of conveyor casing 46. A water level controlling float valve 56 communicates with the municipal water supply or otherwise and a float 58 controls the water level within the tank 54 as well as the pool 14, as indicated by the line 60 therein.

The primary incinerating flame 36 may be fed by any suitable fluid carbonaceous fuel such as gas or oil. In the specific illustration shown in FIGS. 1 and 4, the type of burner illustrated therein is intended for the consumption of gas but it is to be understood that this is primarily illustrative rather than restrictive.

Regardless of the type of fuel utilized for the primary combustion flame 36, it is preferred that the burner be of the type that produces a conical flame front which intersects the spray cone of refuse particles discharging from discharge end 28 of conduit 16 into the combustion zone 62. Such preferred type of burner arrangement is illustrated in detail in FIG. 4 which specifically comprises a gas-fired burner 64 that is shown for illustrative rather than restrictive purposes.

Referring to FIG. 4, it will be seen that the burner is unitary with the discharge end 28 of conduit 16 and includes an annular flangelike connecting plate 66 fixed by welding to discharge end 28. A circular row of gas ports 68 formed therein around the terminal upper end of discharge member 28, said row of gas ports being surrounded by a short circular collar 70. A gas supply manifold chamber 72 is formed by a short cylindrical wall 74 which is welded at opposite ends respectively to the undersurface of the connecting plate 66 and a circular bottom plate 76. Bottom plate 76 has an inlet port 78 therein which communicates with a fitting 80 that is connected to a fuel supply conduit 82 shown in FIG. 1. A baffle 83 is fixed to end 28 of conduit 16 to diffuse the fuel discharge within chamber 72.

Primary combustion air is introduced to the combustion zone 62 by being included with the refuse material fed to the incinerator through the inlet conduit 16. Hence, the refuse is preferably airborne. An appropriate material handling fan 90 of suitable capacity for example, is utilized to blow the comminuted refuse material through the conduit 16, whereby substantially each particle of refuse is surrounded by air, whereby highly efficient, high temperature combustion occurs as soon as the fuel which issues upwardly through the burner ports 68 is carbureted with said primary combustion air.

Initial ignition of the flame is effected by a suitable igniter 84 which, as indicated diagrammatically in FIG. 1 may be of an electrical type although, if desired, an appropriate pilot gas flame of suitable type may be employed. The nature of the flame may be inspected at any time by a flame viewing tube 86 which extends through the bottom refractory liner 34, for example, as well as the adjacent sidewall of the unit 10. Conventional exemplary blue glass lens may be included in the outer end of said tube to close the same and also facilitate viewing the flame.

A suitable conventional thermocouple 88 extends through the wall of the unit 10, as shown in exemplary manner in FIG. 1, at an appropriate level and location so as to control the delivery of fuel to the primary burner 64. By such arrangement, a minimum operable temperature is maintained within the combustion zone by providing such automatic regulation of the intensity of the primary incinerating flame 36. The intensity of the flame and the corresponding temperature produced in the combustion zone will vary in accordance with the type of refuse being disposed of by the incinerator. For example, without limitation thereto, it has been found that a suitable temperature for the disposal of general hospital refuse will vary between 1,400 and 1,600.degree. F.

In accordance with the preferred method of operating the incinerator unit, as referred to above, comminuted waste material is entrained within an appropriate air current by suitable industrial material-handling fan 90 which is illustrated in FIG. 1 in exemplary manner. The fan is operated by appropriate power at a desired rate of speed adequate to develop not only desired incinerating temperatures but also to eliminate the need for any induced draft fan such as is frequently required in existing incinerators to insure adequate withdrawal of products of combustion to a stack or other discharge means. Thus, by using adequate air pressure within the conduit 16, any need for an exhaust fan in association with exhaust conductor 92 is completely eliminated. It also will be understood that the exemplary section of the exhaust conductor 92, as shown in FIG. 1, is representative of means to convey products of combustion either to a stack, vent, or other means communicating with the atmosphere.

In accordance with the desired operation of the incinerator unit 10, the products of combustion thus discharged to atmosphere should be completely free of smoke or any other solid particles of material, odor, gases in any appreciable amount other than CO.sub.2 and N.sub.2 or similar odorless gases, or other form of atmosphere-contaminating material. Because of the intimate and thorough mixing of the refuse with the delivering air stream, less excess air is required for complete combustion than in conventional incinerators, with resulting minimum formation of objectionable oxides of nitrogen and corresponding odor.

Primarily for purposes of preventing the escape of any type of solid material, such as ash or otherwise from the combustion zone, the unit 10 includes a material separator 94, shown in FIG. 1, which preferably is coaxial with the interior of the combustion zone 62. Said separator preferably is formed from high heat resistant ceramic material. A composite fluid conductor 96, 96' extends around the periphery thereof for transmission of cooling water therethrough. A similar composite conductor 98, 98' extends around the periphery of discharge throat 100 at the lower end of discharge member 102 which also preferably is coaxial with the combustion zone 62. Accordingly, the path of exhausting products of combustion is generally in the direction of the exemplary arrows 104.

The conductor 96, 96' on separator 94 is partially supported in spaced relationship below the upper conductor 98, 98' by a plurality of supporting tubes 112 and 114 which are evenly spaced circumferentially respectively between the conductor segments 96, 98 and segments 96', 98', said composite conductors being approximately of the same diameter and construction. Accordingly, the circular conductors 96, 96' and 98, 98' and the tubes 112 and 114 somewhat resemble a cage construction through which the exhausting products of combustion pass into discharge member 102 for transmission to exhaust conductor 92.

Cooling water is passed through the segments of the composite conductors 96, 96' and 98, 98' in a somewhat circuiteous path illustrated diagrammatically in FIG. 6. Referring to FIG. 1 and especially FIG. 6, it will be seen that cooling water is introduced through a plurality of inlet tubes 108 to several locations in conductor segment 98. The conductor segments of each set are separated from each other by suitable walls 110 shown in the diagram of FIG. 6. A plurality of evenly spaced conducting tubes 112 extend between the conductor segments 96 and 98 and a similar number of tubes 114 extend between segments 96' and 98', said tubes respectively being on opposite sides of the dividing walls 110. In FIG. 1, tubes 112 are shown due to the sectional nature of the FIG. but is will be understood that a similar number of tubes 114 extend between segments 96' and 98'. Also, in diagrammatic FIG. 6, only several of each of tubes 112 and 114 are illustrated so as not to crowd the FIG. but serve to illustrate the flow pattern with the arrows.

Additional conducting tubes 116 extend through separator 94 between corresponding conductor segments 96 and 96', as shown in FIG. 6, whereby the circulating path of the cooling water is from inlet tubes 108 to the segment 98, as shown in FIG. 6, down to the lower conductor segment 96, through tubes 116 to conductor segment 96', up tubes 114 to conductor segment 98', and then discharging therefrom through a plurality of discharge tubes 118. Tubes 108, 112, 114, 116 and 118 are also shown in FIG. 1. It also is to be understood that other similar or equivalent circulating arrangements may be utilized in lieu of that specifically illustrated.

The principal function of the separator 94 is to facilitate maximum combustion of the waste material. This is achieved by forming the lower surface of separator 94 in the shape of a very flat cone with the apex extending downward. Such a surface serves effectively to deflect solid material which may tend to rise with the upsurging incinerating flame and discharging products of combustion and cause the same to be deflected into the confined annular passage around the periphery of separator 19 where combustion is intensified. The cagelike formation of tubes 112 and 114 through which the products of combustion pass functions somewhat as a centrifugal separator of solid ash material and cause it to fall to the ash-receiving equipment, due to a swirling effect described hereinafter.

An additional function of the cooling arrangement, afforded by conductor 96 in particular, is to minimize the effect of the intense incinerating heat against the separator 94 and thereby extend the life thereof as much as possible. To further enhance this, if desired, said separator may have additional conductors extending transversely or otherwise therethrough, in communication with conductor 96 for example, and thereby additionally circulate cooling water through the separator 94. Such cooling absorbs heat from the separator 94 as well as the products of combustion which engage the conductors 96 and 98 and thereby lower the temperature of the exhausting products of combustion below that at which they otherwise would enter discharge member 102 for example. Under some circumstances, it has been found that such reduction in temperature is as much as approximately 300 or 350.degree. F. where, for example, the combustion zone 62 has a temperature of between 1,400 and 1,600.degree. F., depending upon the temperature and rate of flow of the cooling water.

Especially where the incinerator is employed in establishments which as an office building, apartment house, hotel, hospital, or the like, there usually is need for hot water. By circulating the cooling water which enters the inlet tube 108 to effect cooling of the separator 94 and associated elements as described above, it is obvious that the temperature of the cooling water is substantially increased by the time it discharges through tube 118. Accordingly, discharge tube 118 may be connected to the hot water supply system of the establishments referred to above and thus effect economy in furnishing such hot water.

Additional economies also may be effected by including heat exchange tubes 120 or the like, of suitable design which extend between headers 120', or otherwise, though which air may be forced by blower 121, for example. This further cools the discharging gases as well as furnishing heated air for delivery through conduit 121' to warm-up air inlet 18. Thus, inexpensive preheating of the inlet stream of waste material is provided. A highly advantageous result of cooling the discharging products of combustion is that in the event there is need, for any reason whatever, to scrub the discharging products of combustion to insure absolute purging thereof of any air-contaminating constituents, the volume of the gases to be handled by such scrubbing apparatus will be less than if said gas is discharged at a higher temperature. Thus, such scrubbing apparatus may be of smaller size than otherwise, coupled with lower costs of operating the same.

Further to insure complete combustion of all consumable waste material within the combustion zone 62, the incinerator unit 10 is additionally provided, if desired, with an inlet 126 for secondary combustion air which may be obtained from a suitable source and introduced under pressure within a desired range. As best seen from FIG. 3, the inlet 126 is directed tangentially through the wall of the incinerator unit, preferably at a level below the separator 94 as shown in FIG. 1. Such arrangement also induces swirling in the combustion zone and thereby produces a vortex which retards the rate of discharge of products of combustion. Thus, the products of combustion are retained in the combustion zone for a longer period than otherwise, which insures maximum efficiency in incineration of combustible waste material by the consuming flame in zone 62 and also produces maximum efficiency in the separator section.

Still another auxiliary means is provided for additionally insuring complete combustion of waste material, the same being in the form of a secondary burner 128 which preferably extends through the upper portion of the wall of the incinerator unit, such as in the vicinity of the cagelike arrangements which support the separator 94, as is clearly shown in FIG. 1. Said illustrated location, however, is exemplary rather than restrictive. Also, said secondary burner may be provided with fluid fuel, either gas or oil, and as illustrated, the burner is a gun type. Such illustration, however, also is illustrative rather than restrictive. The ignition of the secondary burner 128 is controlled by thermocouple 130 which, for example, extends into the discharge member 102 as shown in exemplary manner in FIG. 1. The thermocouple also may be provided with suitable temperature indicating gauge 132, if desired.

Normally the temperature induced by the secondary burner will insure the prevention of smoke from occuring but smoke occurrence depends also upon the types of waste being burned. Accordingly, to further insure against smoke from occurring, a smoke-detecting device 133 is provided which also preferably is connected buy suitable circuitry, not shown, to the igniter for secondary burner 128. Thus, when smoke occurs from incomplete combustion, for example, in the event the temperature is not adequate to activate thermocouple 130, it will be detected by the device 133 and said device will ignite secondary burner 128 so as to increase the combustion temperature and thereby eliminate smoke or noxious gases from passing into the atmosphere. The smoke-detecting device may be of any industrial type such as one using a photoelectric cell capable of being adjusted or "tuned" to a desired degree of smoke density capable of activating the same.

For convenience of inspection in particular, the incinerator unit 10 may be provided with other ports 134 for location of suitable sampling or testing couples, if desired. Suitable observation ports 136 of conventional construction also preferably are located at appropriate locations within the shell of unit 10. The location of the ports 134 and observation ports 136 usually are not on the exemplary center lines on which they are shown in FIG. 1. The same also pertains to igniter 84, viewing tube 86, thermocouple 88, secondary burner 128 and pyrometer 130. For additional exemplary disposition of some of said elements, see FIG. 2. Also, the viewing ports 136 have conventional closures, such as blue glass lenses, or otherwise, and the thermocouple and other ports which are not used are suitably plugged until needed.

* * * * *

Current U.S. Class:	110/187 ; 110/190; 110/212; 110/216; 110/259
Current International Class:	F23G 5/08 (20060101); F23G 5/12 (20060101); F23g 005/12 ()
Field of Search:	110/7,8,16,15,18