US1640158A - Furnace - Google Patents

Description

J. F. O. STRATTON FURNACE Aug. 23, 1927. ,158

Filed Aug. 28. 1925 4 Sheets-Sheet 1 #5200225? Lfoizrzffl 5222222571.

1927' J. F. o. STRATTO'N FURNACE Filed Aug. 28. 1925v 4 Sheets-Sheet 2 Aug. 2

J. F. O. STRATTON FURNACE Filed Aug. 28. 1925 4 Sheets-Sheet 3 1927' J. F. o. STRATTON FURNACE Filed Aug. 28

1925 4 Sheets-Sheet 4 Patented Aug. 23, 1927.

PATENT OFFICE.

JOHN F. O. STBA'ITON, 01 CHICAGO, ILLINOIS.

runner.

Application filed August 28, 1925. Serial No. 52,998.

The present invention relates to improvements in. furnaces, and has particular reference to furnaces of the type disclosed in my Patent No. 1,505,505, issued August 19,

That patent discloses a vertical jetfurnace in which a blast or jet of air is directed upwardly through the throat into the combustion chamber. The blast of air agitates the fuel which is fed in at the top of the furnace, raises or holds it in suspension to secure complete combustion, and separates the combustible from the non-combustible portions. To create this blast, air under 5 pressure is admitted to the ash pit which serves as a pressure chamber, and from there passes through a long narrow space defined by a pair of parallel intercepting members preferably consisting of grate bar construction and directly underlying the throat. In entering the ash pit, the air passes over the outside surfaces of the walls of the throat and through and over the intercepting members, thereby cooling the same. The intercepting members are continuously reciprocated in unison to shift the region of the blast back and forth across the throat, thereby reaching all portions of the fuel and keeping them in mobile condition. The

non-combustible portion of the fuel falls through the space between the intercepting members into the ash pit.

I have found that slag falling at the sides of the throat onto the intercepting members tends to adhere thereto, thereby preventing proper agitation of the fuel bed, and preventing air from passing through the grates in said members to clean and cool the latter. An important object of the present invention therefore resides in the provision of means for automatically cleaning the intercepting members.

A more specific object is to provide for one or each of the intercepting members, a cleaning or slicing member reciprocable thereon and oppositely thereto to clean the associated intercepting member and inci-' dentlv to stir and agitate the material in the throat.

When the furnace is in operation, molten slag runs down the inclined walls into the throat and onto the slicing members and intercepting members where it solidifies due to the chilling from the comparatively lowtemperature of the intercepting members and the low-temperature air passing through these. If the region of the blast is shifted to the sides of the throat, the relatively cold air will chill the slag and cause it to solidify before reaching the bottom of the throat, and usually at or just above the upper edges of the throat. Upon solidifying the sla tends to adhere to the inclined walls, an

gradually a. ma of solid slag will collect at opposite sides of the throat, thereby lowering the efliciency of the furnace and necessitating frequent cleaning. An important object of the present invention therefore is to provide a furnace of the above character in which the intercepting members are given a stroke substantially less in length than the width of the throat and in a central range spaced from the sides of the throat; and in which each slicing member is moved a substantial distance into the throat to the adjacent edge of the space as the latter is shifted in the opposite direction into its extreme position at that side of the throat, thereby slowly shoving the cooled matter on the underlying intercepting member into the blast to causea separation of the combustible and non-combustible portions.

Further objects are to provide means for scraping the slicing members. as they are being withdrawn from the throat, and to provide means for varying the movements of the parts. a

Still another object is to provide scraping members for the slicing members, and serving also to ash pit outwardly over the slicing members. A general object is to provide a new and improved furnace which is simple and sturdfiy in construction, and. which is highly e cient in operation.

Further objectsand advantages will be come apparent as'the description proceeds.

In the accompanying drawings, Figure 1 is a vertical sectional view of a furnace embodying the features of my invention.

Fig. 2 is a fragmentary enlarged section- 211 view taken along line 2-2 of Fig. 6.

Fig. 3 is a horizontal sectional view of the throat taken along line 33 of Fig. 1.

Fig. 4 is a plan view of the throat.

Fig. 5 is a horizontal sectional view'taken along line 5-5 of Fig. 1 and showing the operating mechanism.

direct the air entering the Fig. 6 is a sectional view taken along line 6-6 of Fig. 4.

Fig. 7 is a fragmentary front View of a part of the operating mechanism.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiment, but it is to be understood that I do not thereby intend to limit the invention to the specific form disclosed but aim to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed in the appended claims.

Referring more particularly to the drawings, while the main body of the furnace may conform to any suitable construction, it preferably comprises a front wall 10, a rear or bridge wall 11, and inclined front and rear bottom walls 12 and 13, respectively. The space bounded by these walls constitutes a combustion chamber 14. Fuel, such as coal 15, may be continuously fed from a hopper 16 having a feed screw 17 through a spout 18 in a set oil of the front wall 10 into the upper part of the combustion chamber 14. The front wall 10 is provided with an opening 19 having a closure 20, and through which fuel may be thrown into the furnace by hand at any time. The inclined walls 12 and 13 are lined with suitable refractory material, such as bricks or blocks and converge to the upper edges of a long narrow throat 21. The inclined walls serve to direct coal and slag falling thereon into the throat.

Located at the lower portion of the furnace and bounded by four walls 22, 23, 24 and 25 is an ash pit 26 which also serves as an air pressure chamber. Ashes may be removed from the pit 26 through an opening 27 in the wall 22 normally closed by the door 28.

The throat 21 is constructed of a plurality of sections which fit closely together. and which preferably consist of blocks 29 shaped to form straight parallel side walls. and blocks 30 shaped to form curved end walls. The upper edges of the blocks 29 and 30 are curved or inclined, as indicated at 31, to

form short continuations of the inclined walls 12 and 13, and the sides thereof extend vertically below said edges preferably for av distance of about six inches. This depth is preferred to a shorter depth since it substantially equals that which a suitable banked coal fire would have. As a result, the banked fire bed would have straight vertical sides, and if congealed could still. be easily removed. By increasing the depth of the throat, the inclined walls 12 and 13 are also brought nearer to the expanding blast of air and to the area of combustion, thereby maintaining the fuel and slag on the walls at a higher temperature, and preventing fuel from passing along the walls beyond the range of the blast into the throat.

The blocks 29 and 30 are hollow metal castings capable of withstanding extremely high temperatures. Each side block 29 is formed with an air passage 32 having a downwardly extending nozzle 33 opening into the ash pit 26 at the lower end of the throat. The outer wall of the nozzle 33 terminates a short distance above the inner wall to permit lateral deflection of the discharged air. Surrounding the blocks 29 and 30 constituting the throat 21 is an air chamber 34 which communicates with the air passages 32. The air chamber 34 includes passages 35 around the end blocks 30 to connect, the side spaces. In the present instance, each passage 35 is con structed of an upper wall .36, a lower wall 37 and an end wall 38, the upper and lower walls extending up to the end blocks 30. Preferablythe inner edge of the lower wall 37 is spaced a small distance from the end blocks 30 to provide a narrow opening 39 adapted to permit the escape of a small amount of air for cooling purposes. One side of the air chamber 34 is connected to an intake conduit 40 of any suitable shape adapted to receive compressed air from a suitable source (not shown). The inner walls of the blocks 29 and 30 are corrugated as shown to provide extensive outer cooling surfaces over which the incoming air must pass, and to compersate for any variations due to expansion or contraction. Air entering the chamber 34 will be discharged through the nozzles in to the ash pit 26 to maintain a predetermined pressure therein. 15y constructing the throat 2-1 of a plurality of hollow castings, of which the side castings have independent air passages and discharge nozzles, the discharge is uniformly distributed in fixed jets about the throat, thereby producing a uniform cooling effect. The air chamber 34 thus constitutes a form of heat exchange serving to cool the wallsof the throat 21 and to preheat the air to be used in combustion. The air cooled throat herein described is fully disclosed and claimed in my copend-ing application Ser. No. 52,999, filed August 28, 1925.

The air chamber 34 and throat 21 may be supported in any suitable manner, and in the present instance are mounted at opposite ends on four channel shaped columns 41, the walls 36, 37 and 38 being rigidly secured thereto. These columns extend up from masonry columns 42 built in from the side walls 24 and 25 of the ash pit 26.

Mounted on each of the columns 41. is one of a plurality of inwardly extending brackets 43 supporting a pair of parallel spaced tracks 44 and 45. Each track preferably comprises two closely spaced parallel inverted T-shaped beams or bars. Movtracks are a plurality of anti-friction members, each of which consists of a pair of peripherally grooved sheaves 46 riding on the edges of the T- sha ed beams and rigidly connected by a shaft 47. In the present instance, four antifriction members, one on each end of each track are provided. Mounted for bodily reciprocation on the friction members is a pair of tracks 48 and 49 each of which comprises two parallel bars connected together by means of spacers 50, and engaging the peripheral grooves in the sheaves 46. The front ends of the bars of each of the tracks 48 and 49 are bent toward each other,"and are connected by a pin 51 to which the rear end of an operating link 52 is pivotally secured.

Mounted on the tracks 48 and 49 for re-' ciprocation therewith across the front portion of the throat is an intercepting member 53 which comprises a rectangular frame 54 having end brackets 55 rigidly secured to the tracks. A second intercepting member 58 having a similar frame 59 is mounted for reciprocation across the rear portion of the throat 21. The frame 59 however is not rigidly secured to the tracks 48 and 49, but is provided with end brackets 60 in which rollers or sheaves 61 are mounted. The sheaves 61 engage the inner bars of the tracks 48 and 49 for adjustment toward and from the first mentioned frame. A plurality of grate bars 62 are mounted in the frames 54 and 59, and are formed with side lugs 68 to provide the usual spacing. The intercepting members 53 and 58 are spaced apartto define a long narrow space or passage 64 serving as a nozzle for directing a blast of air from the ash pit 26 into the combustion chamber 14. To provide means for adjusting the width of the space 64, and for reciprocating the frame 59 with the tracks 48 and 49, the brackets 60 are formed with upstanding lugs 65 to which the rear ends of two spaced adjusting links 66 are pivotally secured.

Two cleaning or slicing members 67 and 68 are provided for dislodging slag and other material adhering to or collecting on the intercepting members 53 and 58 respectively. The members 67 and 68 comprise a plurality of slicing grates 69, the free inner ends of which are respectively reciprocable in the front and rear sides of the throat and on the underlying grates 62 to and from the front and rear edges of thespace 64, and the outer ends of which are formed with hooks 70 fitting respectively over two horizontal shafts 71 and 72 extending along opposite sides of the throat. The front shaft 71 is mounted in the free upper ends of two spaced arms 73 pivotally mounted at their lower ends on the front brackets 43 at opposite sides of the ash pit 26. The arms 73 ably mounted on the are pivotally connected near their upper ends by means of studs 74 to the rear ends of two operating links 7 5. The rear shaft 72 is similarly mounted on arms 76 sup ported by rear brackets 43 and pivotally connected by means of studs 77 to two operating links 78. The slicing grates 69 are formed with side lugs 79 to provide the usual spacing and are dimensioned to extend be-' yond the sides of the-throat 21 in all positions of reciprocation. The ends of the intercepting members and slicing members also extend beyond the ends of the throat 21. The grates 62 and 69 permit small amounts of cold air to percolate through the intereepting members and slicing members to cool the latter and to cause the slag falling thereon to harden. While grates preferably are employed, it is to be understood that any other suitable means having small openmgs for the passage of air may be employed.

To prevent fuel orslag from being carried on the grates 69 out of the throat 21, a plurality of scraper members 80 are provided. In the present instance, four scraper members are provided, and each member comprises a bar 81 extending along one half of one side and curved partially around one end of the throat 21, and a pair of spaced arms 82 pivotally secured in brackets 83 on the under side of the air chamber 34. The bars 81 rest on the grates 69 directly beneath the nozzles 33, and each bar is formed with an upstanding flange 84 for deflecting part of the air from the nozzle overhead outwardly over the surfaces of the grates 69. Air thus passes over and through the grates 69 to cool the latter.

The front ends ofthe links 52, 66, 75 and 78 are pivotally connected to four pairs of levers 85, 86, 87 and 88 mounted on four shafts 89, 90, 91 and 92 respectively. These shafts extend transversely in the front of the ash pit 26, and through air tight bearings 93 in' the side wall 25 into a chamber 94 open at the top to the atmosphere, and are journaled in spaced bearing brackets 95. and 96 in opposite sides of the ash pit and in a bearing bracket 97 in the chamber 94. The levers extend upwardly from the shafts so as to have a horizontal throw. and are subject to adjustment as will be hereinafter described. Secured to the ends of the shafts 89, 90, 91 and 92 in the chamber 94 are four substantially horizontally disposed lever- S 98, 99, 100 and 101 respectively which are pivotally connected to the lower ends of four links 102, 103, 104 and 105 respectively, extending vertically through a hole 106 in the floor 107 at the front of the furnace. The levers 98 and 101 extend forwardly. and the levers 99 and 100 extend rearwardly so that upon movement of the links 102. 103, 104 and 105 in like directions, the intercepting members and the slicing members will be reciprocated in opposite directions.

At their upper ends, the links 102, 103, 104 and 105 are adjustably attached vrespectively to four horizontally extending sector plates 108 formed in )arallel spaced relation on a plate 109 pivota ly mounted in a supporting standard 110. Each sector plate 108 is formed with an arcuate slot 111 in which a bolt 112 is adjustably mounted. One end of the bolt 112 is pivotally secured to one of the links 102, 103. 104 and 105. and the other end is provided with a hand wheel nut 113 for clamping the bolt in ad justed position in the slot 111. The bolt is also provided with a hand lever 114 whereby it may be moved in the slot 111 when the nut 113 is loosened either to effect an adjustment or to manually operate the associated link. It will be evident that by adjusting the vertical links, the levers on the horizontal shafts in the ash pit 26 will be adjusted angularly, thereby changing their position and also changing the horizontal or effective component of their throw for a given angular movement. The plate 109 is formed with a downwardly extending arm 115 which is connected through a link 116 to a crank arm 117 of a reduction gearing 118 driven by any suitable means (not shown). The operating mechanism herein described for the tracks and the grates is fully disclosed and claimed in my copending application Ser. No. 53,000, filed August 28, 1925.

The adjustment is such that the frame 59 is .reciprocated through substantially the same distance as the tracks 48 and 49 to maintain the space 64 at a fixed Width throughout the operation. The space 64 is shifted only across the central area of the throat, and the slicing members are periodically projected a substantial distance into the throat to meet the space at a substantial distance from the sides. The throat is constructed of a width permitting however a substantial movement of the space 64.

In operation of the furnace, crushed fuel 15 is charged into the furnace from the spout 18 in the form of a falling stream.

The fuel may be initially ignited in any well known manner as by the use of gas jets or other equivalent devices.

Air enters through the conduit 40 into the .air chamber 34. a portion of the air passing downwardly through the adjacent nozzles 33 in the side blocks 29, and the remaining portion passing around the end blocks 30 to the nozzles 33 on the remote side of the throat 21. A small amount of air also passes through the end openings 39 into the ash pit. In passing around the outer surfaces of the corrugated walls of the end blocks 29 and 30 and through the nozzles 33 and openings 39, the air cools the walls of the throat, thereby preventing overheating. Part of the air discharged from the nozzles 33 passes through the spaces between the grates 62 and 69, and part is laterally deflccted by the scraping members 80 to pass over the surfaces of the grates 69, into the ash pit 26, thereby cleaning and cooling the grates. From the ash pit, the air is forcibly discharged in the form of a blast through the space 64 between the intercepting members 53 and 58 into the combustion chamber 14. The blast of air expands and tends to hold the fuel in suspension. The course of the air is indicated in the drawings by arrows.

The fuel is consumed while in suspension. Parts of the fuel fall on the inclined Walls 12 and 13, and are directed thereby into the throat 21. -Molten slag runs down the inclined walls into the throat and onto the grates 62 and 69. The slag there is caused to solidify by the relatively cold air percolating up through the spaces between and cooling the grates. The non-combustible material has a greater specific gravity than the incandescent and partially volatilized combustible material. A pressure is maintained in the ash pit such that the force of the blast of air will allow the non-combustible material to fall through the space 64 into the ash pit, and will retain.the combustible material in suspension. The width of the space 64 between the intercepting Incinbers can be adjusted by adjusting the connection between the link 103 and the associated sector plate 108, and the range of-reciprocation can likewise be adjusted by adjusting the links 102 and 103 relative to the sector plates.

The intercepting members 53 and 58 are reciprocated to shift the region of the blast of air slowly back and forth across the throat, but not to the very sides of the throat. By shifting the region of the blast of air all parts of the fuel in the furnaces are reached. The slag and fuel on the grates 62 are dislodged and moved into the blast of air by the slicing grates 69 which are reciprocated oppositely to the members 53 and 58, thereby cleaning the grates and also agitating the material to permit efficient separation. Thescraping members 80 serve to clean the slicing grates 69. By cleaning the grates 62 and 69 efiicientcooling is permitted. The range and extent of reciprocation of the slicing grates can be adjusted through the links 104 and 105.

Upon loosening-the nuts 113, the above parts can be selectively operated manually by means of the hand levers 114.

It will be evident that I have provided an efiicient vertical jet combustion furnace capable of fine adjustments to suit different operating conditions, and not likely to get out of order.

Lil]

I claim as my invention:

1. A furnace having, in combination, a combustion chamber, a throat formed in'the bottom of said combustion chamber, an air pressure chamber below said throat, movable intercepting means directly beneath said throat, said interceptingmeans consisting of a plurality of independently movable sections spaced apart to define a space for directing a blast of air from said pressure chamber into said combustion chamber, means for moving said sections in unison to shift said space back and forth across said throat, and means movable oppositely to said sections and overlying the same to dislodge matter collecting thereon.

2. A furnace having, in combination. a combustion chamber, a throat formed in the bottom of said combustion chamber, an air pressure chamber below said throat, movable intercepting means directly beneath said throat, said intercepting means consisting of a plurality of independently movable sections spaced apart to define a space for directing a blast of air from said pressure chamber into said combustion chamber, means for moving said sections in unison to shift said space back and forth across the throat, the range of said movement being substantially less than the width of said throat, and means automatically operable to .clean said sections.

3. A furnace having, in combination, a combustion chamber, a throat below said combustion chamber, an air pressure chamber below said throat, movable intercepting means directly beneath said throat, said intercepting means consisting of a plurality of independently movable sections spaced apart to define a space for directing a blast of air from said pressure chamber into said combustion chamber, means for moving said sections in unison to shift said space back and forth across said throat, including a pair of slicing members positioned on said sections, and means for moving said slicing members oppositely to said sections to dislodge matter collecting on the latter.

4. A furnace having, in combination, a combustion chamber, a throat formed in said combustion chamber, an air pressure chamber below said throat, movable intercepting means directly beneath said throat, said intercepting means consisting of a plurality of independently movable sections spaced apart to define an opening for directing a blast of air from said pressure chamber into said combustion chamber, means for moving said sections to shift said opening transversely of said throat, a slicing member on one of said sections, and means for moving said slicing member over said last mentioned section to remove material therefrom.

5. A furnace having, in combination, a combustion chamber, having a throat, an air pressure chamber below said throat, movable intercepting means directly beneath said throat,-said intercepting means consisting of a plurality of independently movable sections spaced apart to define a space for directing a bla t of air from said pressure chamber into said combustion chamber, means for reciprocating said sections to shift said space transversely of said throat, a slicing member on one of said sections. and means for reciprocating said slicing member continually and oppositely to said last mentioned section to remove material on the latter.

6. A furnace having. in combination, a combustion chamber, having a throat, an air pressure chamber below said throat, movable intercepting means directh beneath said throat, said intercepting means consisting of a plurality of inde 'iendcntlv movable sections spaced apart to define a nozzle for directing a blast of air from said pressure chamber into said combustion chamber, means for reciprocating said sections in unison to shift said nozzle baclc and forth transversely of said throat, a pair of slicing members movable on said sections and oppositely thereto, and means for reciprocating said slicing members. i

7.. A furnace having. in combination. a

combustion chamber having an opening in the bottom thereof. an air pressure chamber below said opening. movable intercepting means interposed between said chamber and said opening. said means consisting of a plurality of independent spaced sections, means for moving said sections to change the position of the space thcrcbetween under said opening, slicing members interposed between said sections and said opening, means for moving said slicing members over said sections to clean the latter. and means positioned to clean said slicing members. 8. A furnace having, in combination, a combustion chamber having an opening in the bottom thereof, an air pressure chamber below said opening, movable intercepting means interposed between said chamber and said opening, said means consisting of a. plurality of independent spaced sections. means for moving said sections to change the position of the space thcrehetwecn, a pair of slicing mt-mbers interposed between said sections and said opening, and means for mov ing said slicing members over said sections to clean the latter.

9. A furnace having, in combination, a combustion chamber having an opening in the bottom thereof, an air pressure chamber below said opening, a plurality ot spaced apart intercepting members interposed between said chamber and said opening. the space between said members serving as noz- Zle means for directing a blast of air of predetermined size and force through said opening into said comlmstiou chamber,

means for adjusting said members relative to each other to change the size of said space and for moving said members in unison to change the position of said space beneath said opening, and means automatically operable to clean said members.

10. A furnace having,'in combination, a combustion chamber havin a throat opening, an air pressure cham er communicating with said opening, a pair of spaced apart members disposed across said opening and serving to direct a blast of air from said pressure chamber into said combustion chamber, a pair of cleaning members (lisposed at opposite sides of said throat and interposed between said first mentioned members and said opening, and means for moving said first mentioned members and said cleaning members relative to each other, and for moving said first mentioned members across said opening, whereby said blast is shifted into different positions and said first mentioned members are cleaned.

11. A furnace having, in combination, a combustion chamber having a throat opening, an air pressure chamber communicating with said opening, a pair of spaced apart members disposed across said opening and serving to direct a blast of air from said pressure chamber into said combustion chamber, a pair of slicing members interposed between said first mentioned members and said opening, and means for reciprocating'said first mentioned members under said opening to shift the blast and for reciprocating said first mentioned members and said slicingmembers relatively to each other to clean theformer.

12. A furnace having, in combination, a combustion chamber having a throat opening, an air pressure chamber communicating with said opening, a pair of spaced apart members disposed across said opening and serving to direct a blast of air from said pressure chamber into said combustion chamber, a pair of cleaning members interposed between said first mentioned members and said opening, means for reciprocating said first mentioned members under said opening to shift the blast and for reciprocating said first mentioned members and said cleaning members relatively to each other to clean the former, and means for independently adjusting the movements of said members.

13. A furnace having, combustion chamber having a throat opening, an air pressure chamber con'ununicating with said opening, a pair of spaced apart members disposed across said opening and serving to direct a blast of air from said pressure chamber into said combustion chamber, a pair of cleaning members on said first mentioned members, means for reciprocating said first mentioned members under intercepting means to shift in combination, a

said opening to shift the blast and for reciprocating said first mentioned members and said cleaning members relatively to each other to clean the former, and scraping members disposed at opposite sides of said opening and resting on said cleaning members for cleaning the latter.

1%. A furnace having, in combination, a combustion chamber having a narrow opening in the bottom thereof, an air pressure chamber below said opening, intercepting means directly below said opening and defining a narrow longitudinal space for admitting air in the form of a blast from said pressure chamber into said combustion chamber, means on said intercepting means for cleaning the latter, and means for moving said intercepting means to shift said space and for moving said intercepting means and said cleaning means relatively to each other to clean said intercepting means.

15. A furnace having, in combination, a combustion chamber having a narrow opening in the bottom thereof, an air pressure chamber below said opening, intercepting means directly below said opening and defining a narrow longitudinal space for admitting air in the form of a blast from said pressure chamber into said combustion chamber, means on said intercepting means for cleaning the latter, means for moving said a said space and for moving said intercepting means and said cleaning means relatively to each other to clean said intercepting means, and means resting on said cleaning means for dislodging matter collecting on the latter.

16. A furnace having, in combination, a combustion chamber having an opening, an air pressure chamber communicating with said opening, intercepting means disposed across said opening, said intercepting means defining a space constituting a nozzle for admitting air from said pressure chamber into said combustion chamber, means for reciprocating said intercepting means, and means resting on said intercepting means for cleaning the latter at each end of its reciprocation.

17. A furnace having, in combination, a combustion chamber having a throat opening in the bottom thereof, a pressure chamber below said opening, intercepting means disposed across said opening and controlling the passage of air from said pressure chamber into said combustion chamber, and a pair of slicing members disposed at opposite sides of said opening and reciprocable over said intercepting means to clean the latter.

18. A furnace having, in combination, a combustion chamber having a throat opening in the bottom thereof, a pressure chamber below said opening, intercepting means reciprocable acros said opening, said intercepting means defining a space for directing air from said pressure chamber in the form of a blast through said opening into said combustion chamber, means for reciprocating sa-id intercepting means to shift said blast back and ,forth across said opening, the range of said reciprocation being substantially less than the Width of said opening in the direction of said reciprocation, a pair of slicing members disposed at opposite sides of said opening and reciprocable on said intercepting means, and means for reciprocatin said slicing members oppositely to said intercepting means, said last mentioned reciprocation causing said slicing members to be alternately moved laterally into said throat opening to the side edges of said space for the purpose of cleaning said intercepting means.

19. A furnacehavmg, in combination, a-

combustion chamber, a throat in the bottom thereof, a pressure chamber communicating With said throat, intercepting means disposed across the throat opening, said intercepting means defining a space for admitting air from said pressure chamber into said combustion chamber and having a plurality of small restricted openings, means for admitting air to said pressure chamber, cleaning members disposed at opposite sides of said throat and having a plurality of small openings, said members resting on said intercepting means for removing ma terial collecting on the latter, and means associated with said last mentioned means and operative to direct part of the lncoming an over the surface of said mterceptmg means and said members and part of the inv coming air through said openings into said pressure chamber to cool said intercepting means and said members.

20. A furnace having, in combination, a combustion chamber having a throat, intercepting means positioned across said throat, and defining a space opening into said throat, a pressure chamber communicating through said space with said throat, means for reciprocating said intercepting means to shift said space back and forth across said throat but through a range substantially less than the width of said throat in the line of reciprocation, a slicing member at one side of said throat and resting on said intercepting means, and means for reciprocating said slicing member oppositely to said intercepting means and in a range such that it is projected periodically into said throat to the edge of said space.

21. A furnace having, in combination, a combustion chamberhaving a throat opening in the bottom thereof, means for 'creating an upwardly directed blast of suflicient force to erupt fuel falling to the bottom of said combustion chamber into said throat, means for confining said blast to a predetermined area less than the cross sectional areaofsaid throat, means for moving said last mentioned means transversely of said throat to shift the region of said blast, said blastconfining means being positioned substantially below said throat, and means automatically operable to clean said blast confining means.

In testimony whereof, I have hereunto affixed my signature.

JOHN F. o. STRATTION.

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