US3687094A

US3687094A - Incinerator apparatus

Info

Publication number: US3687094A
Application number: US67378A
Authority: US
Inventors: Richard Menigat
Original assignee: Metallgesellschaft AG
Current assignee: GEA Group AG
Priority date: 1969-08-29
Filing date: 1970-08-27
Publication date: 1972-08-29
Anticipated expiration: 1989-08-29
Also published as: AT303246B; GB1293234A; CH526748A; DE1943855A1

Abstract

A system for incinerating municipal waste and refuse wherein a movable grate serves as the sole means for controlling the rate at which the refuse traverses the incinerator. The movable grate preferably comprises a plurality of rotary grate members driven so that their upper surfaces advance the refuse while their lower sides carry the ash away from the burning chamber.

Description

[ Aug. 22, 1972 finite States tent Menigat Kremer........................ Gunson [54] INCINERATOR APPARATUS 3,469,544 9/1969 [72] Inventor: Richard Menigat, Dietzenbach, Ger- 3038421 6/1962 many [73] Assignee: Metallgesellschaft Aktiengesellschaft,

FOREIGN PATENTS OR APPLICATIONS Great 10/35 Frankfurt am Main, Germany Aug. 27, 1970 ABSTRACT [22] Filed:

[21] Appl.No.:67,378

[30] Foreign Application Priority Data Aug. 29, 1969 A system for incinerating municipal waste and refuse wherein a movable grate serves as the sole means for Germany..........P 19 43 855.2

controlling the rate at which the refuse traverses the incinerator. The movable grate preferably comprises a plurality of rotary grate members driven so that their [52] US. Cl. R, 110/40 R [51] Int. 5/00 [58] Field of Search.........................110/8, 18, 35, 40 pp surfaces advance the refuse while ei lower sides carry the ash away from the burning chamber.

9 Claims, 8 Drawing References Cited UNITED STATES PATENTS 3,031,982 5/1962 Gordon et 10/40 V PATENTEmusze m2 3.687; 094

SHEET 1 [IF 5 In ven tor Richarcl Menigaf jqttomey PATENIEDwszs m2 SHEET 2 BF 5 QZQN 9 5 M mc PATENTEDAUBZQ m2 3; e87; 094

SHEET 3 BF 5 Fig.4

l RTYYII R In van (or; Richard Men/gar {RNA Attorney PATENTEDMIS29 1912 3587094 Richard Men/gar PATENTEBwszs 1912 SHEET 5 BF 5 Inventor, Richard, Men/gar BY R Attorney INCINERATOR APPARATUS l. FIELD OF THE INVENTION 2. BACKGROUND OF THE INVENTION Massive incinerator systems have been proposed heretofore for large municipalities and metropolitan areas to burn the refuse and garbage accumulated during refuse collection by truck systems and the like. Such incinerators may have traveling grates or the like carrying the refuse from the input side to the output side of the combustion chamber in which the garbage or refuse is consumed by fire, in part as a result of selfburning and in part by the combustion of fuels which may be introduced into the chamber through burners or can be mixed with the refuse. However, for small cities and municipalities, large-size incinerator systems are not suitable because, on the one hand, insufficient refuse is collected to operate the incinerator efficiently and because, on the other hand, the high capital costs of such systems are prohibitively expensive for small municipalities having a low tax base.

3. OBJECTS OF THE INVENTION It is the principal object of the present invention to provide an improved incinerating method and system, especially intended for small or moderate sized municipalities and institutions which will avoid the disadvantages of large incinerator installations and yet provide efficient and economical destruction of refuse and garbage.

I may also mention the fact-that incinerator systems have been proposed heretofore with both traveling grates and crane-type transfer of the refuse into the combustion chamber, such systems being suitable only for large municipalities and governmental units. It has also been proposed to provide small incinerator units in which an inclined shaft feeds the refuse to the combustion chamber by gravity, combustion taking place at the bottom of the shaft. The latter systems have proved to be ineffective since the movement of the refuse to be incinerated is a function of its composition which may vary within a wide range and because the nature of the packing of the refuse and its tendency to prevent the passage of air at least through lower portions under the weight of a column of refuse thereabove, prevents efficient burning. The small and moderate municipalities, therefore, have been faced with a choice between inefficient and often ineffective incinerators of small size or larger installations which are likewise of low efficiency and high operating cost, but are prohibitively expensive.

It has, moreover, been proposed to treat the refuse, before it is introduced into the smaller incinerators of the character described, by comminution or homogenization to eliminate variations in the packing and overall texture of the refuse and permit the combustion thereof in a more uniform manner. Comminution, shredding and like devices, however, are of high cost, are prone to breakdown and introduce a further step in the refuse-disposal chain which substantially complicates the latter.

It is, therefore, another object of this invention to provide an improved incinerator, especially for smallsize or moderate-size towns, cities or other municipalities and governmental units, which avoids the aforedescribed disadvantages and affords efficient combustion of refuse and garbage of the type conventionally collected from such governmental units and nevertheless permits efficient burning thereof at relatively low capital cost and operating cost.

4. SUMMARY OF THE INVENTION These objects and others which will become apparent hereinafter are attained, in accordance with the present invention, with an incinerator system having a downwardly and forwardly inclined shaft into which the refuse or garbage is fed at the top of the shaft, while the advance of the refuse through the combustion chamber is effected solely by a moving-grate system. The passage of the refuse from its storage pile through the incinerator is, therefore, determined exclusively by the movement of the grate.

According to a more specific feature of this invention, the incinerator installation comprises a collection and storage compartment formed with an upwardly and forwardly inclined conveyor which lifts the refuse to the mouth of the previously mentioned downwardly inclined input shaft or column, the lower end of which overlies or communicates with the movable grate whose operation regulates the advance of the refuse through the furnace. The moving grate of the present invention comprises an array of generally parallel and interleaved roller grates which may have coplanar axes and may be tangent along their upper surfaces to a common horizontal plane, the grates all being driven in the same sense so that their upper surfaces move as a forward direction and carry the refuse from one grate roller or drum to the next. The roller grates are, according to the invention, provided with angularly equispaced arc-segmental ribs which are received between the ribs of the adjoining grate roller or drum and which serve to carry the refuse across the floor of the combustion chamber. Furthermore, the codirectionally moving lower surfaces of the roller grates sweep above the floor of the furnace in the opposite direction to carry away the ash.

It has been found to be advantageous to increase the speed of the rotary grate members at the downstream side of the array, advantageously in a stepped or progressive manner so that each succeeding grate travels at a slightly higher speed than the preceding grate and to constitute the rotary grate members as hollow shafts or with hollow shafts to facilitate cooling.

5. DESCRIPTION OF THE DRAWING The above and other objects, features and advantages of the present invention will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

FIG. 1 is a diagrammatic vertical cross sectional view of an incinerator installation embodying the present invention;

FIG. 2 is a vertical section drawn to an enlarged scale of a detail of the system of FIG. 1;

FIG. 3 is a cross section diagrammatically illustrating the junction between two such drums according to the invention.

FIG. 4 is an axial cross section through one of the drums, portions thereof being omitted;

FIG. 5 is a side-elevational view of one of the members of this grate;

FIG. 6 is a side view thereof;

FIG. 7 is a section taken along the line VII-VII of FIG. 5; and

FIG. 8 is a diagram illustrating the distribution of air to the hollow shaft of a rotary grate member according to the invention.

6. SPECIFIC DESCRIPTION In FIG. 1, I have shown an overall view of an installation for incinerating refuse and garbage and particularly an apparatus for use in small municipalities which cannot economically provide large-scale installations.

The installation comprises a storage bunker or chamber 1 which may be located below grate 1a and can be defined by an upwardly inclined wall lb of concrete which includes an acute angle B with the floor 1c of this bunker. At the upper edge of this wall 1b, there is provided a curb 1d against which a sanitation refuse collection or dump truck 1e may be backed up to unload the refuse 1 f. Along the floor 10, there is provided a conveyor arrangement 2 whose lower or upstream end 2a is located beneath the wall lb while the upper end of the conveyor overhangs at 2b, the shaft or column 20 of the incinerator 4. This column which is inclined downwardly and forwardly, terminates in the combustion chamber 4a of the incinerator which has a floor 411 along which an array 5 of grate rollers 5a 5e extends. These grate rollers are shown in detail in FIG. 2 and FIGS. 5-7.

At the downstream end of this array there is provided an outlet 7a at which noncombustibles are discharged as represented at 7. Ash, falling between the grate rollers 5a 5e, collects on the floor 4b and is scraped to an outlet 8a at which ash is discharged as represented at 8. The furnace 4 is provided with an outlet 40 at the downstream end for conduction of waste gases from the furnace. The outlet 40 communicates with a heat exchanger 9, and a dust-removal and gas-cleaning apparatus 11 16 of conventional type. The gas can, therefore, flow through a washer 12 of the multicyclone type in which nozzles 12a and 12b discharge washwater from a line 13 into the gas, the particles of sludge being collected at 12c and 12d and being led from the system at 13. A blower 14 has its suction side connected to the washer I2 and passes the waste gases to a stack 16 via an electrostatic filter 15, the solids of which are washed and returned to the line 13a as represented at a. The heat exchanger 9 serves to preheat the combustion air as will be apparent hereinafter, the air being fed via a manifold a to the furnace through the roller grates 5a See.

The heart of the apparatus of the present invention is, of course, the improved grate arrangement represented at 5. As can be seen from FIG. 4, each of the grate rollers is journaled in a pair of bearings via

respective shaft portions

19a and 1%, one bearing assembly being represented diagrammatically at 190. The

shaft 1% is, in addition to being journaled in a bearing assembly not shown, provided with a splined or polygonal shaft which can be coupled to the drive motor for rotation of the rollers at adjustable speeds. Any conventional adjustable speed transmission may be used for this purpose. The drives of the various rollers 5a 5e, however, are controlled so that each downstream roller 5b, 50 etc. operates at a faster speed than the preceding upstream roller 5a, 5b etc.

Furthermore, as can be seen from FIG. 2, all of the rollers 5a 5e are rotated in the same sense (counterclockwise as represented by arrows D) to convey the refuse at f from below the column or shaft 2c (FIG. 2) across the floor 4b of the furnace. The first rotary grate drum 50, therefore, is located beneath the pile of refuse in column 2c and serves as the feed means for determining the rate at which the refuse is drawn from the column and carried across the furnace.

FIGS. 4 7 illustrate in somewhat greater detail the grate rollers according to this invention. It will be apparent from FIG. 4, for example, that each roller 50 5e comprises a hollow shaft 19 carrying a plurality of axially offset star-shaped grate disks 18 having teeth 17 angularly equispaced about the periphery of each disk and of circular arc-segmental shape. As can be seen from FIG. 3, the teeth of the disks 1' 6', flanked by end pieces E and F, engage between the teeth of the star-shaped disks I" '7" so that slight clearances G are provided between the rollers to permit ash to fall as flydust to the floor lb (arrows I-l). Hence the upper surfaces of all of the drums move to the left (FIG. 2) to carry the refuse thereacross while the interfitting or interleaved arrangement of the drums intensively agitates the layer L of refuse transported across the grate. Since the upstream drums 5a, 5b rotate at slower speeds than the drums 5c and 5d downstream thereof and the latter drums operate at a slower speed than the drum 5e, the initial drying of the refuse along the drums 5a and 5b is carried out with a relatively long residence time while combustion in the zone of grates 5c and 5a is accompanied by increased agitation of the refuse, and the cooling grate Se is highly efficient as a result of the high speed and separation of the residue of the refuse.

Referring now to FIGS. 5 7, it will be seen that the circular arc segments 17 have a generally trapezoidal configuration in the sense that the arc length S of their inner edges is less than the arc length s of their outer edge so that the teeth 17 include angles a which may range between and 120 at their leading and trailing edges 17a and 17b respectively. The edges 17a, 17b etc. are defined between flanks 2b which include angles 7 of 60 to with one another. The angular extent of each tooth will, of course, depend upon the number of teeth in accordance with the relationship to 360]N where N is the number of teeth employed. Preferably, N ranges between 4 and 12 and, in the embodiment illustrated in FIGS. 5 7 N 8 so that m 45.

The hollow shaft 19 has an outer chamber 19d which communicates with the interior 17c of each of the disks 18. The teeth 17 thereof are provided with openings 17d releasing the combustion air into the furnace. As shown in FIG; 7, each of the teeth 17 has a pair of flanks 17d and 17f spaced inwardly from the lateral faces 17g and l7h of the disk and a cylindrical surface l7i. The flanks 17e, 17f and the surface 171' are all provided with openings 17d as described. Furthermore, the

shoulder

17j and 17k adjoining the flank 17e and 17f, are provided with opening 17d. Internally, each of the disks 17 may be subdivided by partitions 18a extending along radii of the drum so that compartments 1817 between such partitions register with respective chambers 21a of the hollow shaft 19. The latter is subdivided by similar partitions 21b into the compartments 21a and is formed with openings 210 along its circumference to register with the chambers 18b. At its lefthand end (FIGS. 4 and 8), the shaft 19 is surrounded by a fluid-distribution hood 21 into which the combustion air, preheated in heat exchanger 9, is fed at 21d. Along the underside of this hood 21, there is provided a shield 2le with seals 21f preventing the entry of air into the chambers 21a of the lower half of the shaft. The remaining chambers, however, receive the air as represented by the arrows M and distributed to the star-shaped disks 18 as previously described. The combustion air, therefore, serves to cool the hollow shaft and the individual elements 18 and the latter have the dual function of advancing the refuse and distributing the combustion air uniformly to the latter. The air emerging from the teeth of the star-shaped elements 18, moreover, loosens the refuse carried by the rotary grates and facilitates transport thereof.

As indicated, the teeth 17 moving to the right along the lower side of each of the rotary grates 5a 5e entrain the ash to the outlet 8a which may be provided with a water-cooled worm for conveying the ash away from the incinerator. At the downstream end of the array of rotary grates, there is provided a comb 22, the teeth of which fit between the teeth of the last grate 5e to dislodge any uncombusted residue. This residue is generally metal or glass which can be collected separately from the ash where, for example, recovery of valuable components (e. g. metal scrap) is desired. In operation, the combustion air introduced into the rotary grates 5a Se is heated to about 400 C in the heat exchanger 9.

Referring again to FIG. 1, l have shown at 6 nozzles for introducing fresh air into the furnace chamber at an intermediate location along its length to bring the waste gases to the most effective temperature for dust separation. The conveyor 2 may be provided with flight for entraining the refuse as shown at 2d in FIG. 1 and is preferably composed of steel plates. Furthermore, means may be provided at the end of the conveyor as shown at 2e for limiting the height of the layer of refuse carried by this conveyor into the column 2e and, indeed, photoelectric means may be provided as represented at 2f to control the conveyor in response to the height of refuse in the column 20. A suction arrangement maintains a constant reduced pressure within the furnace to prevent the outflow of waste gases through the inlet column or shaft and, when further refuse is not to be supplied to the system, this column may be closed via a vertically moving door 3.

The improvement described and illustrated is believed to admit of many modification within the ability of persons skilled in the art, all such modifications being considered within the spirit and scope of the invention except as limited by the appended claims.

lclaim: 1. A refuse incinerator, comprising housing means forming an incinerator chamber having a downwardly extending inlet column at one side thereof; and a moving grate extending along the bottom of said chamber from said column and exclusively controlling the rate at which refuse is fed to and through said chamber, said moving grate comprising an array of interleaved rotarygrate drums all rotated in the same sense, said drums being driven at progressively higher speeds in the downstream direction.

2. A refuse incinerator comprising housing means forming an incinerator chamber having a downwardly extending inlet column at one side thereof; and a moving grate extending along the bottom of said chamber from said column and exclusively controlling the rate at which refuse is fed to and through said chamber, said moving grate comprising an array of interleaved rotarygrate drums all rotated in the same sense, said drums being formed with axially offset star-shaped disks each provided with a plurality of angularly offset teeth, the teeth of one drum being received between the teeth of a pair of disks of an adjoining drum.

3. The refuse incinerator defined in claim 2 wherein said drums each include a hollow shaft carrying the respective disks, said disks being provided with apertures, said incinerator comprising means for distributing combustion air through said shaft to said disks for discharge through said apertures.

4. The refuse incinerator defined in claim 3 wherein each shaft and the respective disks are provided with generally radial partitions to confine the discharge of combustion air from said disks into said chamber to the upper portions only of each drum.

5. The refuse incinerator defined in claim 4 wherein said drums lie in a horizontal plane.

6. The refuse incinerator defined in claim 5, further comprising an upwardly inclined conveyor leading to the top of said column for discharging refuse into the latter.

7. The refuse incinerator defined in claim 6, further comprising means at the upstream side of said array for collecting ash.

8. The refuse incinerator defined in claim 2 wherein said drums are driven at progressively higher speeds in the downstream direction.

9. The refuse incinerator defined in claim 2 wherein said array of drums includes an inlet drum beneath said column and operated at a speed controlling the rate at which the refuse is fed to and through said chamber.

Claims

1. A refuse incinerator, comprising housing means forming an incinerator chamber having a downwardly extending inlet column at one side thereof; and a moving grate extending along the bottom of said chamber from said column and exclusively controlling the rate at which refuse is fed to and through said chamber, said moving grate comprising an array of interleaved rotary-grate drums all rotated in the same sense, said drums being driven at progressively higher speeds in the downstream direction.

2. A refuse incinerator comprising housing means forming an incinerator chamber having a downwardly extending inlet column at one side thereof; and a moving grate extending along the bottom of said chamber from said column and exclusively controlling the rate at which refuse is fed to and through said chamber, said moving grate comprising an array of interleaved rotary-grate drums all rotated in the same sense, said drums being formed with axially offset star-shaped disks each provided with a plurality of angularly offset teeth, the teeth of one drum being received between the teeth of a pair of disks of an adjoining drum.