US3664278A

US3664278A - Method and apparatus for incinerating solid materials

Info

Publication number: US3664278A
Application number: US70086A
Authority: US
Inventors: Gerhard Steen
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-09-08
Filing date: 1970-09-08
Publication date: 1972-05-23
Anticipated expiration: 1989-05-23

Abstract

Combustible material is incinerated by piling about a horizontal overhead girder until the material closes the space between the ground and the girder on both sides of the girder, leaving an empty space below the girder that serves as a combustion chamber whose two side walls are the material to be incinerated. Oxygencontaining gas is preheated and fed to the combustion chamber lengthwise of the girder and out through downwardly and laterally outwardly inclined openings through the underside of the girder. The combustion chamber is maintained at subatmospheric pressure by discharging the flue gas through a chimney.

Description

United States Patent Steen [54] METHOD AND APPARATUS FOR INCINERATING SOLID MATERIALS [72] Inventor: Gerhard Steen, Lappenbergsallee 8c, 2

Hamburg 19, Germany 221 Filed: Sept. 8, 1970 21 Appl.No.: 70,086

[52] U.S,Cl ..110/8R,l10/18R,110/72R [51] Int. Cl. ..F23g 5/00 [58] FieldofSearch ..110/7,7A,8R, 18 R, 72, 110/l6,17, 19

[56] References Cited UNITED STATES PATENTS 1,339,729 5/1920 Walsh ..110/18 1,566,608 12/1925 Kruse..... 110/18 X 633,300 9/1899 Wegener ..110/8 [451 May23', 1972 969,158 9/1-910 Diplock ..ll0/l8 Primary Examinerl(enneth W. Sprague AttorneyYoung & Thompson ABSTRACT Combustible material is incinerated by piling about a horizontal overhead girder until the material closes the space between the ground and the girder on both sides of the girder, leaving an empty space below the girder that serves as a combustion chamber whose two side walls are the material to be incinerated. Oxygen-containing gas is preheated and fed to the combustion chamber lengthwise of the girder and out through downwardly and laterally outwardly inclined openings through the underside of the girder. The combustion chamber is maintained at subatmospheric pressure by discharging the flue gas through a chimney.

21 Claims, 5 Drawing figures Stefanyk ..110/17 x' PATENTEnmAYza I972 3.664.278

Fig. 2

OaN

METHOD AND APPARATUS FOR INCINERATING SOLID MATERIALS The present invention relates to methods and apparatus for the incineration of predominantly solid combustible and waste materials, such as refuse, wherein the materials are introduced into a combustion chamber having side walls formed by the materials themselves, and are burned therein with preheated oxygen-containing gas such as air, and the flue gas and molten solids are continuously discharged.

It is already known to provide methods and apparatus for the combustion of solid materials, with simultaneous melting of the combustion residues. Thus, as in the conventional pulverized coal-firing processes, it is possible to burn the finely divided combustible materials in a suspended condition or on the other hand to conduct the combustion in a furnace with fixed or movable grates as well as a liquid or slag discharge. Such methods and apparatus, however, are unsuitable for the incineration of refuse, as the latter has a composition which varies greatly as to particle size, the nature of the material, and its heating value, and since a preliminary comminution is not only technically difficult but also too expensive.

For the incineration of refuse, grateless pit furnaces are known in which the refuse is introduced by mechanical metering devices from above into a circular pit in which it is predried and carbonized and then incinerated in a combustion chamber which is bounded laterally by the refuse itself. This chamber is upwardly closed by the central part of the pit furnace, and the incineration in the chamber is conducted by means of preheated air blown into the chamber. The flue gas is withdrawn, together with the liquid slag, at the bottom of the combustion chamber and is subjected to a secondary combustion in an annular chamber in the furnace mantle, this second combustion being conducted in the presence of additional air. This conventional pit furnace, although capable of burning waste materials of various types, requires complicated conveying and metering devices which easily get out of order, and also requires external and internal furnace walls equipped with flue gas channels and air preheating channels. Furthermore, it is necessary in known apparatus of this type to preliminarily comminute the supplied refuse to a certain minimum size by means of crushing devices. Also, the settling of the refuse in the annular pit presents difficulties which can result in undesired flame breakthroughs in the upward direction.

Accordingly, it is an object of the present invention to provide methods and apparatus for the incineration of solid materials, which avoid the above disadvantages and which make it possible to effect combustion without any special crushing and metering devices, in as simple and inexpensive manner as possible, the combustion being independent of the particle size, the composition and the heating value of the substances to be incinerated.

According to the present invention, predominantly solid combustible and waste materials such as refuse are introduced into a combustion chamber whose side walls are formed by the material itself and are incinerated therein with preheated oxygen-containing gas such as air. The flue gas and the liquid residue are discharged. To form the combustion chamber, a fireproof or refractory deck in the form of a horizontal girder is disposed a distance above the ground at a height sufficient to define the roof of a combustion chamber whose side walls are defined by the material itself which feeds to the combustion chamber by gravity. The combustion chamber is maintained at subatmospheric pressure.

Also according to the invention in its more particular forms, the oxygen-containing gas is preheated by heat exchange with the flue gas. The feed of the material to the combustion chamber is augmented by horizontally pushing the material at a distance from the side walls of the combustion chamber. During start-up, the oxygen-containing gas is preheated directly or indirectly by externally supplied heat. Alternatively, pure oxygen or oxygen-enriched air can also be supplied to the combustion chamber.

The invention also comprises apparatus for the incineration of predominantly solid combustibles and waste materials such as refuse in a combustion chamber formed between the underside of a fireproof overhead wall in the form of a girder, the chamber being defined laterally by the material to be incinerated. Means are provided for the introduction of preheated oxygen-containing gas such as air into the combustion chamber, as well as means for withdrawing the slag and the flue gas. The material is fed from above about the girder and feeds to the combustion chamber by gravity. Means are also provided for maintaining a small subatmospheric pressure in the combustion chamber.

The overhead girder of the present invention is preferably provided with one or more internal feed duets with outlet openings disposed on the under side of the girder, these openings being directeddownwardly and diagonally laterally outwardly of the girder, through which at least part of the oxygen-containing gas is fed to the combustion chamber. To avoid overheating, the girder can also contain cooling pipes.

The flue gases withdrawn from the combustion chamber are discharged through a chimney which can be provided with preheating conduits for the oxygen-containing gas. Between the combustion chamber and the chimney, conventional devices for dust separation can be interposed. The combustion chamber communicates at one of its ends beneath one of the ends of the girder with the lower end of the chimney. By introducing the flue gas tangentially into the chimney, a cyclone effect can be obtained. 1

The floor of the combustion chamber can be inclined downwardly from both sides toward the vertical longitudinal midplane of the girder, and one or more discharge openings for the slag can be provided along the floor. The floor can be lined witl-l a refractory material or not, it being possible also to use the natural soil as the floor of the combustion chamber. -In this latter case, a more or less deep or softened zone is formed on the surface, depending on the temperature of the combustion chamber, wherein the less readily fusible substances accumulate during operation of the incinerator. An undesirably great lateral expansion of the melting zone can be prevented by the installation of heating pipes at a suitable depth beneath the combustion chamber in the soil. The discharge opening for the slag can be in the form of an overflow or siphon.

In accordance with a preferred embodiment of the inven' tion, the overhead girder has a substantially triangular cross section with an underside that is planar or concave. It is through this underside that the exit openings for the oxygencontaining gas extend. At the ends of the overhead girder, transverse walls can be provided having at least a scalable aperture therethrough for inspecting the combustion chamber. For the introduction of liquid and/or gaseous combustibles or waste materials, as well as for blowing in pure oxygen or oxygenenriched air, special nozzle devices are pro vided that discharge into the girder and/or the combustion chamber.

When the material to be incinerated does not suitably feed by gravity to the combustion chamber, mechanical agitators in the form of horizontally reciprocable members can be arranged at a distance laterally of the combustion chamber, these agitating members having stationary covers on their upper sides so that they do not support the material. The material to be incinerated may be confined between walls that slope downwardly toward each other and that extend lengthwise substantially parallel to the girder, and these walls can be provided with a low friction surface.

The material to be incinerated is simply piled up about the overhead girder. For this purpose, a ramp can be provided on one or both sides of the apparatus for the direct discharge of vehicles, and/or conventional endless conveying devices such as conveyor belts can be used for this purpose.

For incineration systems having a large capacity, several overhead girders can be disposed side by side at suitable distances apart, and these can be separated from each other or not by partition walls so as to provide one or a plurality of bunkers open at their top.

By thus providing one or more of the features of the present invention as enumerated above, the incineration operation can be improved and made less expensive, relative to the prior art, because the previously needed comminution and metering devices, as well as some of the furnace walls, can be eliminated, and even bulky refuse can be burned without difficulty. In the case of variations of heating value of the material, the floor beneath the combustion chamber has the effect of a compensatory heat accumulator. As the pressure in the combustion chamber is subatmospheric, fire breakthroughs at the top are substantially eliminated. The preheating of the oxygen-containing gas can be suitably effected by heat exchange with the flue gases in the chimney. Moreover, as the combustion in the combustion chamber takes place spontaneously at the temperatures involved, an after-burner chamber is unnecessary. The apparatus according to the present invention can be shielded at the top from the elements by a separate roof; but from a standpoint of the technical feasibility of the method and apparatus, no roof is necessary.

Moreover, as the apparatus of the present invention contains no moving parts, other than the optional agitating members, the wear on the apparatus which is experienced with conventional apparatus is avoided. The liquid slag produced during incineration can if desired be directly cast into cinder block or the like or can be granulated by immersing it in water or can be removed and utilized in any other desired manner. Heat produced during incineration which is not required for preheating the oxygen-containing gas can be recovered in conventional manners, for example by installation of boiler pipes in the chimney for the production of steam.

Other objects, features and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawings, in which:

FIG. I is a somewhat schematic side cross-sectional view taken on the line I-I of FIG. 3, through a refuse incinerator according to the present invention;

FIG. 2 is a cross-sectional view taken on the line IIII of FIG. 1 and ofFIG. 3;

FIG. 3 is a cross-sectional view taken on the line III-III of FIG. land ofFIG. 2;

FIG. 4 is an enlarged fragmentary view of a portion of FIG. 3; and

FIG. 5 is an enlarged fragmentary view of a portion of FIG. 1.

Referring now to the drawings in greater detail, there is shownincinerator apparatus according to the invention, comprising a floor 1 above which are disposed two parallel horizontal overhead girders 2 which are spaced from each other and each of which defines a combustion chamber 7 therebeneath. A chimney 6 communicates with the end of each combustion chamber 7 at 11, and external preheating ducts 12 for the oxygen-containing gas are provided in surrounding relationship about each chimney 6.

The preheated oxygen-containing gas is fed to a feed duct 8 within each girder 2 and thence enters combustion chamber 7 through outlet openings 9 that are inclined downwardly laterally outwardly through the underside of each girder 2.

At its end adjacent chimney 6, each girder 2 is supported fixedly by a transverse wall 22. At its opposite or free end, the girder rests freely in a horizontally displaceable manner in a recess in the wall 27 of the incinerator which is opposite wall 22, on antifriction members thereby to accommodate thermal expansion and contraction of girder 2.

Floor 1 can be lined with refractory brick as shown, or can be bare ground. As shown in FIG. 3, floor 1 is inclined beneath each combustion chamber 7 downwardly on opposite sides of the vertical longitudinal midplane of symmetry of the girder 2, and also downwardly inclined toward the wall 22, so that molten slag can exit through suitable discharge openings 18 as shown at 19 and be conveyed to any desired use.

As is shown in FIGS. 4 and 5, each girder 2 contains conduits 10 for cooling water to prevent overheating, these conduits being in communication with a suitable external cooler 32. If desired, the heat transmitted to the cooling liquid can be utilized in a conventional manner for steam generation.

Liquid or gaseous combustible materials or waste materials can be introduced into combustion chamber 7 by

conduits

25 and 34 seen in FIGS. 1 and 5. Also, additional oxygen in the form of pure oxygen or oxygen-enriched gas can be introduced into feed duct 8 through a nozzle 26 having a cooling jacket 33 thereabout, as seen in FIG. 5.

Between the overhead girders 2, cover girders 21 are disposed parallel thereto and spaced therebetween, with slide members 20 disposed between girders 21 and floor 1. These slide members 20 are reciprocating pusher conveyors having the shape shown in FIG. 2 and are reciprocable in the direction shown by the arrows in FIGS. 3 and 4, by any suitable means (not shown), in order to urge the material 5 laterally into the combustion chamber 7.

Oxygen-containing gas is fed from a blower 30 through preheating ducts 12, the blower 30 imposing on the oxygen-containing gas only enough pressure to overcome the flow resistance of the

ducts

12 and 8. The effect of chimney 6 exerted on combustion chamber 7, however, is sufficient to produce in combustion chamber 7 a subatmospheric pressure despite the continued feed of oxygencontaining gas from duct 8. If desired, an air inlet 31 in chimney 6 can be opened by a controlled amount so as to regulate the temperature of the supplied oxygen-containing gas as required. Inlet 31 can be provided with blower means or the like (not shown).

The entire incinerator is surrounded on three sides by walls 27. A ramp 3 serves for dumping refuse, the refuse trucks backing out on the ramp as shown in FIG. 1 to empty their loads directly on top of the heap of refuse piled above and about the overhead girders 2. Also, refuse can be supplied to the heap by means of a conveyor belt 4 which is preferably bodily reciprocable horizontally above the heap.

From a consideration of the foregoing disclosure, therefore, it will be evident that all of the initially recited objects of the present invention have been achieved.

Although the present invention has been described and illustrated in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invention as defined by the appended claims.

Having described my invention, I claim:

1. A method for the incineration of solid combustible material, comprising piling said material about a horizontal girder spaced above the ground until the material encloses the space between the girder and the ground on both sides of the girder with an empty space beneath the girder that serves as a combustion chamber, burning the material in the combustion chamber at subatmospheric pressure while supplying to the combustion chamber preheated oxygen-containing gas, and removing from the combustion chamber flue gas and a liquid residue.

2. A method as claimed in claim 1, and preheating said oxygen-containing gas by heat exchange with said flue gas.

3. A method as claimed in claim 1, and pushing said materia] horizontally toward the combustion chamber to replenish the material that burns in the combustion chamber.

4. A method as claimed in claim 1, and preheating said oxygen-containing gas by heat from an external heat source during a start-up period.

5. A method as claimed in claim 1, in which said oxygencontaining gas has a higher oxygen content than air.

6. A method as claimed in claim 1, and directing at least a portion of said oxygen-containing gas into said combustion chamber through said girder.

7. A method as claimed in claim 1, and directing at least a portion of said oxygen-containing gas into said combustion chamber through said girder in directions that are inclined downwardly and laterally outwardly toward both sides of said girder.

8. Grateless apparatus for incinerating predominantly solid combustible and waste materials, especially refuse, comprising a substantially horizontal fireproof girder spaced above the ground, means to heap up the combustible material against said girder so as to form a closed empty combustion chamber therebeneath which on at least one side is defined by the combustible material itself, means for feeding preheated oxygencontaining gas into said combustion chamber, means for maintaining said combustion chamber at a pressure below the pres sure above the piled combustible material, and means for withdrawing flue gases and molten combustion residue from said combustion chamber.

9. Apparatus as claimed in claim 8, said means for feeding oxygen-containing gas to the combustion chamber including means for conducting said oxygen-containing gas lengthwise through said girder and laterally outward out through the underside of said girder.

10. Apparatus as claimed in claim 9, said girder having openings through the underside thereof for the discharge into said combustion chamber of said oxygen-containing gas, said openings being directed downwardly and laterally outwardly toward both sides of said girder.

11. Apparatus as claimed in claim 8, and cooling conduits disposed in the girder and means to pass a cooling liquid through said cooling conduits.

12. Apparatus as claimed in claim 8, and a chimney communicating with one end of said combustion chamber adjacent one end of said girder for the removal of flue gases from the combustion chamber.

13. Apparatus as claimed in claim 12, said chimneybeing in heat exchange relationship with said oxygen-containing gas thereby to preheat the last-named gas.

14. Apparatus as claimed in claim 8, the ground beneath said girder sloping downwardly toward one end of the girder, there being a discharge opening for said molten residue at the lower end of the ground beneath said girder.

15. Apparatus as claimed in claim 8, said girder having a substantially triangular cross section with the apex of the triangle directed upwardly.

16. Apparatus as claimed in claim 8, and means for discharging material by gravity about the girder from above the girder.

17. Apparatus as claimed in claim 8, and horizontally reciprocating pusher means spaced laterally from the girder for pushing material laterally into said combustion chamber.

18. Apparatus as claimed in claim 17, and means covering said pusher means from above so as to prevent said material 7 from resting onjsaid pusher means.

19. Apparatus as claimed in claim 8, and nozzle means for directly injecting combustibles into the combustion chamber.

20. Apparatus as claimed in claim 8, and downwardly converging side walls on opposite sides of said girder and extending from the ground a substantial distance upward to define a hopper that extends upwardly beyond the girder.

21. Apparatus as claimed in claim 8, there being a plurality of said girders disposed in parallel laterally spaced relationship.

Claims

3. A method as claimed in claim 1, and pushing said material horizontally toward the combustion chamber to replenish the material that burns in the combustion chamber.

5. A method as claimed in claim 1, in which said oxygen-containing gas has a higher oxygen content than air.

8. Grateless apparatus for incinerating predominantly solid combustible and waste materials, especially refuse, comprising a substantially horizontal fireproof girder spaced above the ground, means to heap up the combustible material against said girder so as to form a closed empty combustion chamber therebeneath which on at least one side is defined by the combustible material itself, means for feeding preheated oxygen-containing gas into said combustion chamber, means for maintaining said combustion chamber at a pressure below the pressure above the piled combustible material, and means for withdrawing flue gases and molten combustion residue from said combustion chamber.

13. Apparatus as claimed in claim 12, said chimney being in heat exchange relationship with said oxygen-containing gas thereby to preheat the last-named gas.

18. Apparatus as claimed in claim 17, and means covering said pusher means from above so as to prevent said material from resting on said pusher means.