US2994367A

US2994367A - Combustion methods and apparatus

Info

Publication number: US2994367A
Application number: US439654A
Authority: US
Inventors: Rallston M Sherman
Original assignee: Silent Glow Oil Burner Corp
Current assignee: Silent Glow Oil Burner Corp
Priority date: 1954-06-28
Filing date: 1954-06-28
Publication date: 1961-08-01
Anticipated expiration: 1978-08-01

Description

Aug. 1, 1961 R. M. SHERMAN COMBUSTION METHODS AND APPARATUS 5 Sheets-Sheet 1 Filed June 28, 1954 INVENTOR RALLS ro/v M SHERMAN M M Arrrs.

Aug. 1, 1961 R. M. SHERMAN COMBUSTION METHODS AND APPARATUS 5 Sheets-Sheet 2 Filed June 28, 1954 /N l E N TOR RALLSTO/V M SHERMAN BY 1 7 040 M W "W Arr'rs Aug. 1, 1961 R. M. SHERMAN 2,994,367

COMBUSTION METHODS AND APPARATUS Filed June 28, 1954 5 SheetsSheet 3 7 1 23/ In H /64 L. 6 t 259 we /0 H In l |/67 49.9

lNVENTOR RALLS TON M SHERMAN y (7W Wwmar/111% Aug. 1, 1961 R. M. SHERMAN 2,994,357

COMBUSTION METHODS AND APPARATUS Filed June 28, 195 5 Sheets-Sheet 4 Aug, 1961 R. M. SHERMAN 2,994,367

COMBUSTION METHODS AND APPARATUS Filed June 28, 1954 5 Sheets-Sheet 5 lNl/EN TOR RAL LS ro/v MLSHERMAQI i 4rr'rs.

tates Patented Aug. 1, 1961 2,994,367 COMBUSTION METHODS AND APPARATUS Rallston M. Sherman, Glastonbury, Conn., assignor to The Silent Glow Oil Burner Corporation, Hartford, Conn., a corporation of Connecticut Filed June 28, 1954, Ser. No. 439,654 13 Claims. (Cl. 1581) My invention relates to combustion methods and apparatus. It has, among its objects, projecting a mixture of fuel and combustion air into a chamber in which it is burned to produce a flame and hot combustion products, and, to secure better and more complete combustion of the fuel, guiding said products through a looped path which causes them to travel through the path of said flame for contact therewith for burning the residual fuel values of such products. It further comprehends, among other things, burning a secondary fuel by the heat produced by a primary fuel and mixing the products of combustion of the secondary fuel with those of the primary fuel and passing the mixture through the path of the flame produced by the primary fuel for burning the residual fuel values of the mixture. A fluid fuel such as gas or oil is preferably employed as the primary fuel. The secondary fuel may be fluid or solid fuel. Such solid fuel may be, for example, anthracite or bituminous coal, coke, or waste material to be disposed of by incineration, in which latter case incineration, or the same together with production of hot gaseous combustion products, may constitute the primary purpose of the apparatus and method.

The invention and its above and other objects will however be best understood from the following description when read in the light of the accompanying draw-- ings, while the scope of the invention will be more particularly pointed out in the appended claims.

In the drawings:

FIG. 1 is a section on the line 11 of FIG. 2, with parts in elevation, of a form of apparatus according to the invention;

FIG. 2 is a section on the line 22 of FIG. 1;

FIG. 3 is a fragmentary section on the line 33 of FIG. 2;

FIG. 4 is a section on the line 44 of FIG. 5 showing a modified form of apparatus according to the invention;

FIGS. 5 and 6 are, respectively, sections on the lines 5-5 and 6-6 of FIG. 4;

FIG. 7 is an elevation of another modified form of apparatus according to the invention;

FIG. 8 is a section on the line 8-8 of FIG. 7, with parts omitted, this section line for convenience in following the drawings also being applied to FIG. 12;

FIG. 9 is a plan of the apparatus, according to FIG. 7, with the cover removed;

FIGS. 10 and 11 are, respectively, sections on the lines 1010 and 11-11 of FIG. 7, these section lines for convenience in following the drawings also being applied to FIG. 12;

FIG. 12 is a section on the line 1212 of FIG. 13, with parts in elevation, this section line for convenience in following the drawings also being applied to FIGS. 8, 9 and 10; and

FIG. 13 is a section on the line 1313 of FIG. 12, this section line for convenience in following the drawings also being applied to FIGS. 8, 9 and 10.

The apparatus illustrated by FIGS. 1, 2 and 3 comprises a casing 1 lined with walls built up of the slab 2, bars 3, and

slabs

5, 7, 9, 11 and 13 to form a box-like combustion chamber 15, the bars 3 internally of the combustion chamber having inclined bafile surfaces 16 which converge upwardly toward each other at the upper transverse corners of the combustion chamber.

Interiorly of the combustion chamber is shown a block 17 which rests upon the bottom wall of the chamber and laterally conforms to the end and side walls thereof. This block is shown as formed with a slot 19 which opens on the upper and lower surfaces of the block and is closed at said lower surface by the bottom wall slab 9 of the combustion chamber so that the slot forms a trough-like recess or passage opening upwardly into the body of the combustion chamber. The slot is shown as extending from the extreme left hand end surface of the block as viewed in FIG. 1 to a portion of the block forming a baifle surface 21 and a vertical surface 23, both of which surfaces are positioned transversely of the slot and extend from one side thereof to the other, the baffle surface as shown extending downwardly to the left as viewed in FIG. 1 from adjacent the right hand end of the upper surface of the block to a portion of the block intermediate its length where it intersects the vertical surface 23, the latter extending downwardly to the lower surface of the block. As shown, the side wall surfaces 25 of the slot convergingly incline downwardly from the upper surface of the block to the upper edges of the lower vertical surfaces 27 of the slot.

As further shown, the lower surface of the block is provided with a groove 29 of rectangular transverse cross-section positioned beneath the baffle surface 21, the side of the groove where it opens on the lower surface of the block being closed by the bottom wall slab 9 of the combustion chamber so as to provide a discharge opening which, as shown, communicates with a discharge conduit 31 for conducting the hot combustion products to the place where they are utilized. The groove 29, if desired, may be of the same horizontal width throughout its extent as that portion of the slot 19 which lies between the vertical surfaces 27 of the slot. As illustrated, however, this groove at its end adjacent the slot is of substantially such horizontal width, but its opposite side Walls converge as shown at 33 (FIGS. 1 and 3) as they extend to the vertical side walls 35 of the remaining and narrower portion of the groove. With the portion of the groove between the vertical side walls 35 of narrower width than that portion of the slot which lies between the vertical walls 27, the products of combustion discharge from the groove at a greater velocity than if the groove were of substantially the same width as such portion of the slot, which higher velocity may be desirable in certain instances of application of the apparatus.

Interiorly of the combustion chamber is shown a baflle member 37 positioned above the block 17 and comprising an approximately rectangular bar-like part 39 supported at opposite ends by the opposite combustion chamber side wall slabs 11. This bar-like part presents the converging, downwardly facing baffle surfaces 43 and the converging, upwardly facing baffle surfaces 45.

The above described parts contained within the casing 1 of the apparatus may be formed of heat refractory material such as silicon carbide, alumina, and like refractories, in finely divided form mixed with a binder, molded to shape and baked, in the usual manner of forming bricks, slabs, blocks, and the like for furnace construction.

As shown, the vertical wall slab 7 of the combustion chamber of FIGS. 1 to 3 is provided with an opening 49 which receives the discharge end portion of a conduit 51 through the open end 53 of which an atomized oil-air mixture may be projected into the combustion chamber. As illustrated, this conduit forms the blast tube of a conventional gun type oil burner, this burner comprising a casing 55 containing an electric motor driven fan for forcing air from the atmosphere through the conduit into the combustion chamber, the amount of air being regulated in the usual manner by adjustable shutters (not shown) on an end of the casing, which shutters control the size of the air intake to the fan. As in the conventional gun type oil burner, a pump 57 driven by the same motor as the fan draws oil through a pipe 59 from an oil tank (not shown) and discharges it under pressure into a pipe 61 in communication with a pipe 63 positioned axially of the conduit 51, the pipe 63 having at its end adjacent the combustion chamber a spray nozzle 65 for atomizing the oil. As in the usual gun type oil burner, the pump is provided with manually adjustable means (not shown) for controlling the amount of oil supplied the nozzle. Preferably, and as is common practice, positioned in the conduit 51 is a circumferential series of vanes 67 for causing a whirling of the air discharged from the conduit so as thoroughly to mix the air with the atomized oil. The burner, as shown, is provided with an ignition spark electrode or electrodes 69 for igniting the mixture projected into the combustion chamber.

In operation the burning mixture projected by the oil burner gun travels horizontally through that portion of the trough which is formed by the inclined Walls 25 of the slot 19 in the block 17 toward the inclined baffle surface 21, which latter deflects such mixture and the flame upwardly out of the trough into the space between the bar-like part 39 and the end wall slab 5 of the combustion chamber. The top wall and adjacent end wall of the combustion chamber aided by the adjacent baffle surfaces 16 and 45 turn the products of combustion toward the left as viewed in FIG. 1 at the upper portion of the combustion chamber, the top and left hand end walls aided by the adjacent baffle surfaces 16 and 45 then turning such products downwardly into the trough where they pass into contact with the flame into the discharge passage formed by the groove 29 for discharge from the combustion chamber, thus to cause the flame and products of combustion produced by it, considered as a whole, to follow the general path indicated by the arrows in FIG. 1, that is to say, in a closed loop for causing the products of combustion produced by the flame again to be acted upon by the flame prior to their discharge from the combustion chamber. The bar-like part 39 and its baffle surfaces 45, and the bafile surfaces 16, may be omitted if desired, but their presence insures satisfactory operation under untoward conditions. The downwardly converging, longitudinally extending surfaces 25 of the trough-like member act to permit ready upward deflection of the expanding flame when it strikes the inclined baffle surface 21. At the same time these surfaces 25 act to guide the downwardly traveling combustion products into the trough and into contact with the flame being projected horizontally through the trough. In the trough these combustion products play over the burning oil-air mixture and pass around it and, to some extent, pass through the outer tenuous confines of the flame. Further, the walls of the trough are heated to high incandescence by the flame, the latter and the downcoming combustion products contacting such walls as they are guided by them and as such products pass about the flame to the bottom portion of the trough, and such contact acts further to promote combustion particularly as such products, as they pass about the flame, are acted upon by both the flame and said walls. The burning mixture forming the flame being of greater density, particularly at its longitudinally extending center portion, than the combustion products descending to the trough, and being projected horizontally with considerable velocity, is not materially deflected downwardly by such combustion products. The oil and air mixture, particularly the portion thereof adjacent the discharge end of the air blast conduit, acts ejector-like, by reason of its high velocity, materially to augment and enforce the downward flow of the combustion products to and into the trough. Also this blast of burning mixture, by such ejector action and by its contact with the products of combustion as they pass around it, acts to sweep such products over the hot walls of the trough when in contact with such walls. A finger of the primary flame may be deflected downwardly and pass into the discharge conduit from the trough, and some of the downwardly traveling combustion products may be caught by the burning mixture and recirculated one or more times through the looped path in the combustion chamber, but in such case without deleteriously affecting the efliciency of the operations and in fact acting to insure complete combustion. It will be noted that the air blast supplied the combustion chamber, and the voluminous amount of combustion products produced therein, create a positive pressure in the combustion chamber which acts to cause a rapid discharge of such products from said chamber.

In practice, the amount of air supplied by the oil burner is preferably, but not necessarily, so adjusted with relation to the amount of oil supplied by it as to secure the maximum primary flame temperature, and maximum degree of combustion of the oil prior to the combustion products being looped back into contact with the primary flame. Under these conditions a bright orange primary flame, indicating the maximum flame temperature and degree of combustion possible, will be produced, and, when the oil is the so-called No. 2. oil usually used in domestic gun type oil burners, the amount of such air will be that which will supply to the oil an amount of oxygen which is about 10 to *12 percent in excess of that stoichiometrically necessary to secure complete combustion of the oil. Adjusting the air in this preferred way it has been found secures best results in respect to securing maximum completeness of combustion by looping the combustion products back to the flame. However the air may be adjusted to secure other colors of flame, in which case the amount of excess oxygen may be anywhere from 6 to 15 percent depending on such color and the particular quality of fuel oil employed. Depending upon the quality of the oil and air adjustment the temperature of the primary flame may be from about 2000 to 30 00 F., and the temperature of the combustion products discharged from the apparatus from about -0 to 2400 F. Where conditions warrant, secondary air may be supplied the combustion products, for example, in the way hereinafter described in connection with FIGS. 4, 5 and 6, for securing maximum efliciency.

The gaseous products of combustion of the primary flame will consist mostly of nitrogen admixed with much smaller amounts of carbon dioxide and carbon monoxide, and commonly will contain small amounts of illuminants, hydrogen, ethane and methane, together with the excess oxygen. These gaseous products ordinarily will also contain finely divided soot forming carbon particles and usually particles of the heavy end fractions of the oil. The carbon monoxide, illuminants, hydrogen, ethane, methane, carbon particles, and said heavy end fractions constitute residual fuel values of the oil, and the amount of such residual values is a measure of the incompleteness of the combustion of the oil. In the usual case of a gun type oil burner operated in the conventional manner this residual fuel value may amount to as much as 25 percent of the total fuel value of the oil. On the other hand, the amount of carbon dioxide present indicates the degree of completeness of combustion of the oil. It has been found from flue gas analysis that passing the flame and products of combustion, considered as a whole, in the above described looped path results in many cases in increasing the combustion of the oil 20 or more percent over that which can be secured under most favorable conditions when using a gun type oil burner in the conventional way, and with a corresponding increase in the temperature and volume of the combustion products being discharged from the apparatus.

When the combustion products produced by the primary flame are looped back and brought into contact with that flame in the way above described the intense heat of the flame and walls of the trough raises the temperature of the combustion products sufficiently to cause the residual oxygen in the downcoming combustion products to burn the residual fuel values of those products. The products of combustion discharged from the combustion chamber are substantially free from soot forming particles, and are entirely odorless. In practice, when burning oil with a bright orange flame, commonly the flame deflected upward by the baffle surface 21 will disappear at a position about midway the height of the barlike part 39, and through the remainder of the path of travel of the combustion products no flame indicating burning of those products will reappear until said products contact the primary flame produced by the gun burner in the trough and the adjacent walls of the trough. In the trough at and beneath the primary flame the secondary flame will reappear and commonly will fill the bottom portion of the trough between its vertical surfaces 27 and also the discharge passage formed by the groove 29 in the bottom of the block 17.

Instead of the apparatus burning oil, it may burn a fuel gas, which may be done by disconnecting the pipe 61 from the pipe 63 and connecting to the latter a pipe leading from a source of fuel gas under pressure, provision being made for regulating the amount of gas so supplied the burner for regulating the amount thereof supplied the combustion chamber by the nozzle 65 and in any of the ways commonly employed in connection with gas burners for supplying furnaces with fuel gas. Also, instead of utilizing a fluid fuel, the burner may utilize a pulverulent solid fuel, for example sawdust or pulverized coal, in such case the pulverulent fuel being projected through and from the blast tube into the trough admixed with a blast of combustion air to form the flame, burners of the gun type for so projecting a blast of pulverulent solid fuel and combustion air being well known. In such case the ash resulting from the fuel will fall to and tend to collect in the bottom portion of the trough beneath the flame, and will be continuously blown from the trough by and with the products of combustion discharging therefrom through the hereinbefore described discharge conduit from the trough.

The apparatus shown by FIGS. 4, 5 and 6 is substantially identical with that shown by FIGS. 1, 2 and 3, except that provision is made for supplying secondary fuel and secondary air to the combustion chamber, while the block 17 of FIGS. 1, 2 and 3 is omitted and a metallic part functioning in a substantially identical way substituted for it. In FIGS. 4, 5 and 6 the same reference numerals are applied to the parts which are common to them and FIGS. 1, 2 and 3.

In the apparatus according to FIGS. 4, 5 and 6 a member 71 is substituted for the block 17 of FIGS. 1 to 3. This member 71, which is formed of heat refractory heat conductive metal such as stainless steel, may be built up of sheet material to form a welded structure having a top wall 73 provided at each of opposite longitudinally extending sides with upstanding flanges 75 which bear against the inner sides of the side wall slabs 11 of the combustion chamber, and having at one end thereof an upstanding flange 77 which bears against the adjacent end wall slab 5 of the combustion chamber. As further shown, the top wall 73 is provided with an opening 79 extending from the edge 81 of said wall, which edge bears against the inner side of the combustion chamber end wall slab 7, to the upper edge of a flat inclined wall 83. Said upper edge of this wall 83 is shown as positioned close to the end wall slab 5 of the combustion chamber, the wall 83 extending inwardly and downwardly of the combustion chamber to a lower edge thereof positioned intermediate the length of the combustion chamber and above its bottom. Also, as shown, from the longitudinally extending horizontal edges of the opening 79 extend downwardly inclined walls 85 which at their lower edges terminate in the same horizontal plane as the lower edge of the in-= clined wall 83. From the lower edges of the walls downwardly extend vertical walls 87, and, from the right hand vertical end edge of one of these walls 87 as viewed in FIG. 4, a transverse vertical wall 89 extends to the corresponding end edge of the opposite wall 87, the upper edge of the wall 89 extending along and being joined to the lower edge of the inclined wall 83. At their lower edges the walls 8'7 and 89 are connected by a bottom wall 91 resting on the upper surface of the bottom slab 9 of the combustion chamber. As shown, the left hand edges of the

walls

85, 87 and 91, as viewed in FIG. 4, abut the inner side of the combustion chamber end wall slab 7. As further shown, the wall 89 is provided with an opening 93 with which communicates one end of a conduit 94 integral with said wall and connected at its opposite end to the discharge conduit 95 for conducting the combustion products to a place where they are utilized, the discharge conduit 95 being fitted into an opening 97 in the combustion chamber end wall slab 5.

In the above described construction according to FIGS. 4, 5 and 6 the inner surface 99 of the inclined wall 83 of the member 71 forms a baflie surface which acts in identically the same way in respect to the burning mixture of oil and air as the baflle surface 21 of FIGS. 1 and 2, while the inner surfaces of the inclined walls 85 of the member and vertical walls 87 thereof form a trough extending from the left hand end of the member, as viewed in FIG. 4, to the walls 83 and 89. This trough functions in identically the same way as the corresponding trough of the apparatus according to FIGS. 1 and 2.

As shown in FIGS. 4 and 5, there is provided a spray or like nozzle 101 for injecting into the upper portion of the combustion chamber a secondary fuel supplied the nozzle by a valve controlled pipe 103. Also, as shown, is provided a conduit 105 which opens through the combustion chamber end wall slab 7 into the chamber formed by the member 71 and the portions of the combustion chamber walls which surround it. This conduit is provided for supplying secondary combustion air to the body of the combustion chamber into which it discharges in an upward direction through openings 107 formed in the top wall 73 of the member 71 to miX with the upwardly traveling products of combustion, thus to provide additional air for burning the secondary fuel injected into the combustion chamber from the nozzle 101. This secondary air in its travel from the conduit 105 to the openings 107 is preheated by contact with and radiation from the hot walls of the metallic member 71.

The secondary fuel injected into the combustion chamber of FIGS. 4, 5 and 6 may be gaseous or liquid fuel. It, for example, may be an oil too heavy to be satisfactorily burned by use of the usual gun burner. Such oil may be supplied the nozzle 101, in which case the nozzle will be a spray nozzle, and the secondary combustion air supplied the conduit 105, by a motor driven pump and fan, respectively, identical with those of the gun burner hereinbefore described, except that the oil discharge pipe 61 from the pump of such gun burner will be connected to the nozzle supply pipe 103 of FIG. 4.

The oil discharged from the nozzle 101 will be ignited by the hot products of combustion of the primary fuel and will burn by reason of the excess amount of primary air, and the secondary air supplied by the conduit 105, the amount of air supplied by this conduit being so regulated that sufficient oxygen will be contained in the products of combustion when they are brought into contact with the primary flame to burn the residual fuel values of the primary and secondary fuels in the way hereinbefore explained.

The nozzle 101 and oil supply pipe 103, instead of being positioned to spray the oil generally horizontally into the combustion chamber, may be positioned as shown at 101A and 103A, respectively, to spray or drip the oil downwardly onto the upper surfaces of the hot bafiie bar 37,

On such surfaces the oil will spread out in a fihn and volatilize to form oil vapors which mix with the combustion products flowing above the bar and burn. The apparatus may be equipped with both the

nozzles

101 and 101A, in which case they may be used either selectively or simultaneously by use of the manually operated valves 103B in the pipes 1413 and 103A, these valves if desired being also adjusted for regulating the amounts of oil supplied the nozzles.

It will be understood that after the secondary fuel is ignited by the heat of the primary flame such secondary fuel will continue to burn even if the primary flame is extinguished. Hence, after the combustion chamber and trough are heated by the primary flame to a high temperature the primary oil supply and secondary air supply may be interrupted while continuing the supply of primary air and secondary oil. The primary air upon such interruptions will continue to flow in the hereinbefore described looped path, while the products of combustion of the secondary fuel will continue to travel as before. Contact of these products of combustion with the hot walls of the trough, and any recycling of such products through the looped path that may occur, will promote complete combustion of the fuel, and combustion will tend to keep the walls of the trough at high temperature. In the event the walls of the trough fall to an undesired low temperature, as may happen when the fuel value or the amount of secondary fuel is inadequate to maintain the desired high temperature and as would commonly be the case, the supplies of primary fuel and secondary air may be reestablished and such fuel ignited by the automatic ignition means (not shown) associated with the primary fuel nozzle 65 or by the secondary flame, and upon the trough again being heated to the desired temperature the supplies of primary fuel and secondary air may again be interrupted.

When both fuels are being burned the trough and the products of combustion passing through the discharge conduit 94 will be at a higher temperature than if but the primary fuel only were being burned. This may be taken A advantage of for automatically interrupting and reestablishing the supply of secondary air and primary fuel in response to the temperature of the walls of the trough or such conduit. For example, a thermocouple schematically indicated at 1% (FIG. 4) may be welded to the conduit so as to impress on the leads 103A connected to the thermocouple elements an electric potential which varies with the temperature of the conduit, the leads extending through a conduit 108B from the thermocouple to suitable control mechanism for effecting such automatic operations. To secure best results this control mechanism should be such as to interrupt the supplies of primary fuel and secondary air when the temperature of those walls of the trough which the downcorning combustion products contact is well within the range that will promote combustion of the residual fuel values of the secondary fuel conatined in such products, and reestablish such supplies when and if such temperature drops to the lower limit of such range. This range may be about 1409 to 2400 F. The temperature of the thermocouple if welded to the conduit 94 may be somewhat diflerent from that of these walls of the trough, but by flue analysis of the combustion products discharging from the conduit when secondary fuel only is burned the control mechanism actuated in response to the temperature of the thermocouple may be set to secure optimum results in respect to completeness of combustion of the secondary fuel without knowing what such temperature actually is.

As will be obvious, the supply of primary fuel may be interrupted and reestablished by closing and opening, respectively, a stop valve placed in the suction pipe of the oil pump supplying the spray nozzle for the primary fuel, and the supply of secondary air may be interrupted and reestablished by closing and opening, respectively, a damper in the conduit 105 supplying such secondary air to the combustion chamber. This valve and damper, as will be understood by those skilled in the art, may be operated by electromagnetic mechanisms, say solenoids, which are energized for opening the valve and damper and deenergized for closing them, or vice versa, such mechanisms being controlled by use of electric relays operated in response to the potential variations impressed by the thermocouple elements on the leads 108A. As such mechanisms and the controlling circuits for them are well known they need not be further described.

It will be understood that the supply of secondary air need not necessarily be interrupted when the supply of primary fuel is interrupted as a high degree of completeness of combustion of the secondary fuel will still be effected but with some sacrifice in the temperature of the products of combustion discharging from the apparatus, which sacrifice in some applications need not be objectionable. However, in such case ordinarily the supply of primary fuel must be reestablished at more frequent intervals because of the greater cooling effect of the excess air on the trough and discharge conduit. Also, in this case of not interrupting the supply of secondary air, it is possible to so control the supply of primary air as somewhat to diminish the amount thereof forming the air blast upon the supply of primary fuel being interrupted, which may obviously be done by use of a damper in the primary air supply connection to the blast tube, which damper the control mechanism governed by the thermocouple will partly close when the supply of primary fuel is interrupted, such partial closure of the damper therefore acting to reduce the total amount of air supplied the combustion chamber and thus acting to keep the combustion products discharging from the apparatus at a higher temperature.

FIGS. 7 to 13 show apparatus according to the invention for burning a solid secondary fuel as well as a fluid primary fuel, the apparatus being useful when desired as an incinerator for waste products to be disposed of.

The apparatus illustrated by FIGS. 7 to 13 comprises a base portion 164 and a removable upper portion 165. The base portion, as shown, comprises a closed circular bottom wall 167 from the periphery of which, and welded thereto at its lower edge, rises a cylindrical wall 163. Interiorly of the base portion is positioned a trough-like member 169 having the opposite

vertical end walls

171 and 173 and the opposite inclined lateral walls 175. This trough-like member, as best shown in FIG. 13, is in transverse cross-section substantially V-shaped, the apex 177 of which rests upon the bottom wall 167 of the base portion of the apparatus. The upper open top of this troughlike member is shown in FIG. 8 as of substantially square cross-section, and communicates with an opening 179 of the same shape and size formed in a horizontal plate 181. The upper peripheral edge of the trough-like member, as best shown in FIGS. 12 and 13, contacts the under side of the plate 181 about the periphery of the opening 179 therein, and is welded to the plate. At its outer edge the plate 181 has a down-turned peripheral flange 183 which is welded to the upper edge portion of the cylindrical outer wall 168 of the apparatus. In this way is formed a chamber 185 interiorly of the base portion and surrounding the trough-like member.

Positioned in the trough-like member is shown an inclined baflle plate 187 which extends from the end wall 173 of said member downwardly to a position intermediate the height and length of the member. As illustrated, the baffle plate at its opposite longitudinal edges has downturned flanges 189 resting upon the inclined walls 175 of the trough-like member. These flanges 189, as shown in FIG. 12, are provided adjacent their lower ends with notches 191 which receive pins 193 fixedly carried by said inclined walls, for assisting in holding the baffle plate in the position shown by the drawings. Also, as shown, the entire portion of the end wall 173 of the trough-like member below the horizontal plane 195 (FIGS. 12 and 13) is cut away to form a substantially triangular opening 197 at the bottom of said end wall. Registering with this triangular opening and welded to the wall 173 about the periphery of said opening is a conduit 199 which is of cross-section like that of the opening and extends through and fits an opening 201 in the wall 168, to the periphery of which last mentioned opening it is also welded.

As shown, the cylindrical wall 168 and the end wall 171 of the trough-like member 169 are formed with aligned

openings

203 and 205 respectively, which openings removably receive the end portion of the air blast tube 207 of an oil or gas burner. This burner may be identical with that described in connection with the apparatus according to FIGS. 1 and 2, except that as shown in FIGS. 10 and 12 the portion of the air blast tube extending through the chamber 185 is provided with perforations 209 for admitting secondary air into said chamber, so as to cause the blast tube to supply secondary air, as well as to discharge a supply of primary air from the free end of the tube into the trough-like member 169, the fan of the burner being of suflicient capacity to furnish both supplies of air. As further shown, the plate 181 defining the top of the chamber 185 is formed with perforations 210' at the opposite sides of said chamber from the blast tube. In the operation of the device the air from the perforations 209 is preheated by the heat of the walls of the trough-like member, and discharges from the chamber through the perforations 210 into the upper portion of the apparatus for providing secondary air for burning a secondary fuel introduced into said upper portion.

As shown, the removable upper portion 165 of the apparatus according to FIGS. 7 to 13 comprises an outer cylindrical wall 211 which is removably telescoped into the cylindrical wall 168 of the base portion, and, at its lower edge, removably rests on the upper side of the plate 181. concentrically positioned with relation to the wall 211 is a cylindrical wall 213, the space between the two receiving a mass 215 of heat insulating material. As shown, the wall 213 at its lower edge removably rests on the upper edge of a cylindrical stiffening flange 214 rising from the plate 181 and welded thereto. At the lower portion of the space between the two walls is shown an annular spacing and connecting member 217 of channelshaped cross-section which is welded to said walls and on which the mass of heat insulating material rests.

At its upper end the wall 213 is shown as provided withan annular peripheral inwardly extending flange 219 on which, and on the top edge of the wall 211, rests a plate 221 having a downturned annular flange 223 resting against the outer side of the wall 211 and welded thereto.

The plate 221, as shown (see FIGS. 9, 12 and 13), is provided with a rectangular opening 225. Resting on the plate and welded thereto at its periphery is a circumferentially disposed angle-iron 227. Removably carried by the upstanding flange 229 of this angle-iron is shown a cover 231 for the opening 225, the cover having the downturned peripheral flange 233 which fits over said flange 229. This cover when removed provides access to the combustion chamber formed by the interior space 235 of the upper portion of the device and the communicating interior space 237 of the trough-like member.

As shown, removably received in the inner space of the upper part of the combustion chamber is a foraminous basket 239. This basket, as shown, is of rectangular cross-section at its top, and comprises, the angle-irons 241 which extend around its top periphery and provide outwardly projecting flanges 243 adapted to rest upon the upper surface of the plate 221 for removably supporting the basket when the latter is inserted through the rectangular opening 225 in said plate. As shown, at the four corners of the basket are downwardly extending angle-irons 245 which are welded to the vertical flanges 247 of the angle-irons 241. At their lower portions the angle-irons 245 at each end of the basket are bent toward each other to form portions 247 thereof which are joined at 249 so as to give the basket in vertical cross-section a pointed bottom. Also, as shown, for reinforcing the frame it is provided, adjacent the portion of the angleirons 245 where bent to form the inclined portions 247 thereof, with flat longitudinally and transversely extending side and end cross-bars 251, while the angle-irons at each end of the frame are connected by an angle-iron 253 extending from the pointed lower end of the frame at one end of the frame to the corresponding pointed end at its opposite end, the cross-bars 251 and angle-iron 253 being welded at their ends to the angle-irons 245. To the frame thus formed are welded the edges of a coarse wire mesh screen 255 for forming the foraminous walls of the basket. As shown, the basket at each end of its top is provided with handles 257 or the like for use in inserting and removing the basket when the cover 231 is removed.

In operation of the apparatus according to FIGS. 7 to 13 the burning oil-air mixture projected into the combustion chamber strikes the baffle plate 187 so that such mixture and the products of combustion are deflected upward. This upwardly deflected flame and products of combustion divide, as indicated by the arrows in FIG. 13, and pass upward into the space at either side of the basket at its end above the baffle plate, the products of combustion in these spaces turning downward at the opposite ends of said spaces and reuniting in the troughlike member and traveling downward through the path of the mixture projected by the oil burner through the trough-like member and hence beneath the baflie plate into the discharge conduit 199.

The basket may be charged with secondary fuel such as bituminous coal, anthracite coal, coke and various combustible waste materials, which form a secondary fuel, the preheated air admitted to the upper portion of the combustion chamber through the perforations 210 providing the secondary air for combustion of the secondary fuel. Preferably, but without limitation thereto, when the coal or coke is employed it is in large lumps, say about the size of a mans fist, so as to provide ready passage through and discharge from the mass of coal of flame and products of combustion. The products of combustion of the primary flame formed by the gas or oil burner 'are at a sufficiently high temperature to ignite the contents of the basket. If the basket is not charged all the way to its top, and when the top level of the charge descends due to consumption of the contents of the basket, the products of combustion of the primary fuel will freely pass through the portion of the basket above the charge.

It will be observed in the above respects that the apparatus according to FIGS. 7 to 13 operates in a way substantially identical with that in which the apparatus according to FIGS. 4 and 5 operates, except that the latter employs two fluid fuels, instead of a fluid fuel and a solid fuel. In both cases the residual fuel values of the products of combustion descending to the lower portion of the combustion chamber are burned by reason of contact of such products with the highly heated walls of the trough and with the primary flame created by the oil or gas burner.

The apparatus according to FIGS. 7 to 13 is so designed as to adapt it for use as an incinerator. For example, the basket may be charged with garbage and other wastes to be disposed of by incineration. It also is very well suited for use in connection with the operation of commercial chicken ranches and brooders for incinerating dead, diseased, or spoiled chickens and the wastes resulting from dressing chickens for the market. All these substances, being mainly organic, are in the nature of a fuel which burns upon the heat of the primary flame suflicien-tly dehydrating such substances and thus supplies a large volume of hot combustion products which mix with the combustion products of the primary fuel supplied by the gas or oil burner, the residual fuel values of the mixture being burned by reason of contact of that mixture with the primary flame and high temperature walls of the trough. When the apparatus is employed as an incinerator the gaseous products discharged are entirely odorless even when the apparatus is initially started up in the cold condition. Odor producing contents of such products are mostly hydrocarbon derivatives such as aldehydes, and the high temperature of the primary flame which such products contact is effective entirely to consume such contents and thus eliminate all odor.

The ash from the material charged to the basket, whether the apparatus is used as an incinerator or otherwise, falls from the basket to the bottom of the troughlike member and is blown from the latter and into and through the conduit 13 9 by the gaseous products of combustion discharging through the bottom of the trough. The bottom portion of this trough-like member at levels below that horizontal plane which includes the lower edge of the baffle plate 187 may be rectangular in crosssection like the corresponding part of the trough shown in FIGS. 4 and 5. However, the triangular shape of this bottom portion provides for a large upper surface area of the ash with relation to the volume of ash tending to collect in said portion, and that facilitates the blowing of the ash therefrom. The hot gaseous products containing the ash may be discharged by the conduit into a separator 259 (FIG. 7) for separating the ash from them, from which separator the hot gaseous products may discharge through the discharge conduit 261 thereof and be conducted to the place where such products are to be utilized or disposed of, while the ash separated from the gaseous products may be removed from the separator through a normally closed door Q63 provided for that purpose. Separators of this character are well known, and as the details of the same form form no part of the present invention the separator need not be further described.

When the apparatus according to FIGS. 7 to 13 is used for incinerating materials that tend to produce products of com busion that are objectionably odorous, for exam ple, materials such as garbage, chicken and other animal flesh, animal wastes, and many industrial wastes, the blast of primary fuel and air mixture may be burned continuously or at least until such odorous products cease to be contained in the combustion gases descending to the trough. In most cases of incinerating such materials only by continuously burning this blast of primary fuel and air mixture will the combustion gases discharged from the apparatus be entirely odorless and initially be so when the apparatus is put in operation in the cold condition.

On the other hand, when the substances being incinerated are such that they form a secondary fuel that gives off non-odorous combustion gases after incineration is continued for a while, or when the secondary fuel is a substance such as coal, coke or other material that gives off non-odorous or substantially non-odorous combustion gases, the apparatus may be operated in a way hereinbefore described in connection with the apparatus according to FIGS. 4, and 6, namely, by interrupting the supply of primary fuel while continuing the blast of primary air upon the trough being heated to a temperature well within such range that despite absence of the primary flame the hot walls of the trough will act on the combustion products of the secondary fuel to cause combustion of the residual fuel values of such combustion products, and upon the temperature of the trough walls falling to the lower limit of such range, as it commonly will after a period of continued operation, reestablishing the supply of primary fuel to again heat the trough walls to within the desired range of temperatures.

This operation of interrupting and reestablishing the supply of primary fuel may be done automatically in the way hereinbefore described in connection with the apparatus according to FIGS. 4, 5 and 6, the control thermocouple 108 in FIG. 12 being welded to the discharge conduit from the trough as in FIG. 4. In the particular form of apparatus shown by FIGS. 7 to 13, however, the only operation necessary to be performed by the mechanism controlled by the thermocouple 108 is that of interrupting and establishing the supply of primary fuel, which may be done for example by use of a solenoid valve in the suction pipe of the oil pump supplying such fuel to the burner nozzle 65 as hereinbefore explained in connection with the apparatus according to FIGS. 4, 5 and 6. It will be observed, however, that in the particular form of apparatus according to FIGS 7 to 13 the secondary air will be supplied to the combustion chamber for so long as the primary air is supplied thereto. Should it be desired to interrupt and reestablish the supply of secondary air to the combustion chamber when the supply of primary fuel is interrupted and reestablished the same may be done by omitting the perforations 209 in the blast tube and providing the combustion chamber with the conduit of FIG. 4, which conduit as hereinbefore explained in connection with FIG. 4 leads from an electric motor driven air fan or blower for supplying the combustion chamber through said conduit with secondary air. When secondary air is so supplied the combustion chamber of FIGS. 12 and 13 such supply may be interrupted and reestablished by interrupting and reestablishing, respectively, operation of the electric motor driving the air fan supplying such conduit, which, as will be understood by those skilled in the art, may be readily done automatically by operation of a switch for connecting and disconnecting such motor to and from the power line 'which energizes it, such switch being opened and closed automatically by an electromagnetic instrumentality actuated by the circuit under the control of the thermocouple.

It will be understood, that within the scope of the appended claims, wide deviations may be made from the forms of the invention herein described without departing from the spirit of the invention.

I claim:

1. The method of simultaneously burning primary fuel in a trough-like space defined by two coextensive walls, and a secondary fuel, which comprises projecting a blast of burning mixture of primary fuel with combustion air along in said trough-like space defined by and between said walls and longitudinally thereof in close proximity thereto so as to be heated thereby to incandescence, laterally deflecting said blast from between said walls after it has traveled a distance between said walls, and, while the temperature of the products of combustion of the deflected blast is above the ignition point of the secondary fuel, bringing said products of combustion and the secondary fuel into contact and introducing secondary combustion air into said products of combustion, all for burning the secondary fuel and causing the products of combustion of the secondary fuel to mix with those of the primary fuel; and burning residual fuel values of such mixed products by guiding such products to such space between said walls at one side of the undeflected portion of the blast for causing such mixed products to contact said walls and said undeflected portion, and discharging such mixed products from between said walls at the opposite side of said undeflected portion at a place spaced, in the direction of travel of said undeflected portion, from the entry of said undeflected portion into the space between said walls for forcing such mixed products so entering the space between said walls 'to flow from the first mentioned side of said undeflected portion to its opposite side in contact therewith and said walls.

2. The method according to claim 1 in which the 13 primary fuel is a fluid fuel and the secondary fuel is presented by a body of substantially solid fuel, the secondary combustion air being introduced into the products of combustion of the deflected burning mixture of primary fuel and combustion air prior to contact of said products of combustion with said body.

3. The method of burning a substantially solid fuel, and a fluid fuel in a space defined by two coextensive upwardly extending walls, which comprises projecting a blast of burning mixture of fluid fuel with combustion air in said space between said upwardly extending walls and longitudinally thereof in close proximity thereto so as to be heated thereby to incandescence, laterally deflecting said blast upwardly after it has traveled a distance between said walls, and, while the temperature of the products of combustion of the deflected blast is above the ignition point of the solid fuel, bringing said products into contact with a body of said solid fuel positioned at a level above that of the undeflected portion of the blast and introducing secondary combustion air into such products, all for burning the solid fuel and causing the products of combustion of the solid fuel to mix with those of the deflected blast; and burning residual fuel values of such mixed products by guiding such products downward into the space between said walls at the upper side of the undeflected portion of the blast for causing such mixed products to contact said walls and said undeflected portion, and discharging such mixed products from between said walls at the under side of the level of said undeflected portion at a place spaced, in the direction of travel of said undeflected portion, from the entrance of said undeflected portion into the space between said walls for forcing such mixed products so entering said space to flow from the upper to the lower side of said undeflected portion in contact therewith and said walls.

4. Apparatus for burning a substantially solid fuel, said apparatus having means forming a combustion chamber, means for supporting in a portion of said chamber that is elevated above the bottom level thereof a bod} of such fuel, means in said chamber at a level below said solid-fuel-supporting portion forming a passage having a pair of opposite walls extending longitudinally of said passage, means for projecting through said passage longitudinally thereof and between said walls a blast of burning mixture of fuel and combustion air in proximity to said walls so as to heat them; means comprising a baflle and an opening from such passage communicating with said solid-fuel-supporting portion of said chamber for laterally deflecting said blast from said passage into said chamber portion for contact of the products of combustion of said blast with said body and further comprising means for introducing auxiliary air into said chamber portion, whereby to ignite and burn said solid fuel and cause the products of combustion of such burning to mix with the products of combustion of the deflected blast; means for discharging products of combustion from said passage at a level adapted to be below the blast to be projected therethrough and at a location spaced at distance adapted to be removed from the entry of the blast into the passage in the direction in which the blast is projected, and means for conducting such mixed products of combustion from said solid-fuel-supporting portion of said chamber to said passage at an area thereof adapted to be adjacent the undeflected portion of said blast for causing flow of such mixed products into said passage for contact with said Walls thereof and for causing part of said products to travel with the blast to said baflie and such part to be recirculated through said portion of said combustion chamber and also to enforce flow of combustion products including said recirculated part of such mixed products from the side of said blast nearer said chamber portion to the side more remote thereto in contact with said walls and said blast whence to be discharged through said discharge means.

5. Apparatus according to claim 4 in which the passage 14 through which the blast is projected has an open top, through which top the blast is deflected for travel through the portion of the combustion chamber in which the body of solid fuel is supported and through which top the mixed products of combustion of the deflected blast and solid fuel enter the passage.

6. Apparatus according to claim 4 in which the passage through which the blast is projected has an open top, through which top the blast is deflected for travel through the portion of the combustion chamber in which the body of solid fuel is supported and through which top the mixed products of combustion of the deflected blast and solid fuel enter the passage, the walls of said passage flaring away from each-other as they extend upwardly to said open top from adjacent the portion of said passage adapted to be occupied by the blast, whereby to spread the blast as it is being deflected from said passage and to contract the mixed products when theyenter said passage and flow toward the undeflected portion of said blast.

7. Apparatus according to claim 4 in which the passage through which the blast is projected has an open top, through which top the blast is deflected for travel through the portion of the combustion chamber in which the body of solid fuel is supported and through which top the mixed products of combustion of the deflected blast and solid fuel enter the passage, the walls of said passage flaring away from each other as they extend upwardly to said open top from adjacent the portion of said passage adapted to be occupied by the blast, whereby to spread the blast as it is being deflected from said passage and to contact the mixed products when they enter said passage and flow toward the undeflected portion of said blast, the baffle being operatively positioned at that end of said passage which is adapted to receive the blast and the discharge means from said passage being so constructed and positioned as to discharge combustion products from the passage in the direction in which the blast is projected through the passage.

8. Apparatus according to claim 4 in which the passage through which the blast is projected has an open top, through which top the blast is deflected for travel through the portion of the combustion chamber in which the body of solid fuel is supported and through which top the mixed products of combustion of the deflected blast and solid fuel enter the passage, the body of solid fuel being supported at a position directly above said open top, the walls of said passage flaring away from each other as they extend upwardly to said open top from adjacent the portion of said passage adapted to be occupied by the blast, the baflle being operatively positioned at that end of said passage which is adapted to receive the blast, the passage having a bottom Wall portion extending longitudinally thereof below and adjacent the space adapted to be occupied by the undeflected portion of the blast, the means for discharging combustion products from said passage being positioned adjacent said bottom wall portion and being so constructed and positioned as to discharge such combustion products from said passage in the direction in which the blast is projected through said passage, whereby ash falling from the solid fuel will enter said passage through its open top and tend to collect at said bottom wall portion of said passage, and whereby the mixed products of combustion which flow from the upper side to the lower side of the undeflected portion of the blast and move with that portion of the blast act to sweep such ash from said bottom Wall portion into said discharge means.

9. Apparatus according to claim 4 in which the passage through which the blast is projected has an open top, through which top the blast is deflected for travel through the portion of the combustion chamber in which the body of solid fuel is supported and through which top the mixed products of combustion of the deflected blast and solid fuel enter the passage, the body of solid fuel being positioned in a forarninous receptacle positioned directly above said open top, the walls of said passage flaring away from each other as they extend upwardly to said open top from adjacent the portion of said passage adapted to be occupied by the blast, the baffle being operatively positioned at that end of said passage which is adapted to receive the blast, the passage having a bottom wall portion extending longitudinally thereof below and adjacent the space adapted to be occupied by the undeflected portion of the blast, the means for discharging combustion products from said passage being positioned adjacent said bottom wall portion and being so constructed and positioned as to discharge such combustion products from said passage in the direction in which the blast is projected through said passage, whereby ash falling from said receptacle will enter said passage through its open top and tend to deposit at said bottom wall portion of said passage, and whereby the mixed products of combustion which flow from the upper side to the lower side of the undefiected portion of the blast and move with that portion of the blast act to sweep such ash from said bottom wall portion into said discharge means.

10. Apparatus according to claim 4 in which the passage through which the blast is projected has an open top, through which top the blast is deflected for travel through the portion of the combustion chamber in which the body of solid fuel is supported and through which top the mixed products of combustion of the deflected blast and solid fuel enter the passage, the body of solid fuel being supported at a position directly above said open top, the walls of said passage flaring away from each other as they extend upwardly to said open top from adjacent the portion of said passage adapted to be occupied by the blast, the bafiie being operatively positioned at that end of said passage which is adapted to receive the blast, the passage having a bottom wall portion extending longitudinally thereof below and adjacent the space adapted to be occupied by the undeflected portion of the blast, the means for discharging combustion products from said passage being positioned adjacent said bottom wall portion and being so constructed and positioned as to discharge such combustion products from said passage in the direction in which the blast is projected through said passage, whereby ash falling from the solid fuel will enter said passage through its open top and tend to collect at said bottom wall portion of said passage, and whereby the mixed products of combustion which flow from the upper side to the lower side of the undeflected portion of the blast and move with that portion of the blast act to sweep such ash from said bottom wall portion into said discharge means, said bottom wall portion of said passage being substantially V- shaped in transverse cross-section for facilitating such sweeping of the ash.

11. Apparatus according to claim 4 in which the passage thro'ugh which the blast is projected has an open top, through which top the blast is deflected for travel through the portion of the combustion chamber in which the body of solid fuel is supported and through which top the mixed products of combustion of the deflected blast and solid fuel enter the passage, the body of solid fuel being supported at a position directly above said open top, the walls of said passage flaring away from each other as they extend upwardly to said open top from adjacent the portion of said passage adapted to be occupied by the blast, the bafiie being operatively positioned at that end of said passage which is adapted to receive the blast, the passage having a bottom wall portion extending longitudinally thereof below and adjacent the space adapted to be occupied by the undeflected portion of the blast, the means for discharging combustion products from said passage being positioned adjacent said bottom wall portion and being so constructed and positioned as to discharge such combustion products from said passage in the direction in which the blast is projected through said passage, whereby ash falling from the solid fuel will enter said passage through its open top and tend to collect at said bottom wall portion of said passage, and whereby the mixed products of combustion which flow from the upper side to the lower side of the undeflected portion of the blast and move with that portion of the blast act to sweep such ash from said bottom wall portion into said discharge means, said means for discharging combustion products from said passage also being positioned adjacent the lower edge of the bafile so that a small part of the blast adjacent its under side will miss the battle and be projected into said discharge means to act to force ash entering said discharge means through that means.

12. Apparatus of the character described having means forming a combustion chamber comprising as an internal part thereof a chamber body, heat refractory incandescible wall means presenting wall surfaces in said combustion chamber forming a trough-like passage which opens transversely thereof at a first portion and at a second portion along one longitudinally extending margin thereof into the body of the combustion chamber, means for projecting through said passage longitudinally there of a blast of burning mixture of fuel and combustion air in close proximity to said wall surfaces so as to heat them to incandescence; baflle means in said second portion of the passage for laterally deflecting said blast from said passage into the body of the combustion chamber through said second transversely open longitudinal marginal portion of the passage after the blast has travelled a distance through said passage; said combustion chamber including means adapted for presenting in the path of the deflected blast a secondary fuel, means including the flow opening from the chamber body to said first passage portion for causing products of combustion of the deflected blast to flow through said body to and past said means adapted for presenting secondary fuel and back into said passage through said first transversely open longitudinal marginal portion of the passage and laterally of the undeflected portion of the blast at the side of said blast portion facing said last-mentioned open passage portion, whereby to cause products of combustion so reentering said passage to be guided by said walls into contact with said undeflected blast portion and part of said reentering products to travel with such blast portion in contact therewith and along and in contact with said walls to said baffle means whence to cause said part to be recirculated through said body of the combustion chamber; and means opening from said first passage portion for discharging products of combustion including said recirculated part thereof from said passage, said discharging means being generally parallel to and at that side of the path of travel of said undeflected portion of the blast which is opposite to said open passage portions and at a location along said path spaced from the blast projecting means for thereby forcing such products of combustion to flow from that side of the undeflected portion which faces said transversely open passage portions to the opposite side of said undeflected blast portion and over and in contact with said \walls and in contact with said blast portion and so as to be discharged in parallelism therewith.

13. Apparatus of the character described having means forming a combustion chamber comprising a base chamber portion and an upper chamber portion with top closure, heat-refractory inoandescible wall means presenting wall surfaces in said base chamber portion and forming an upwardly flaring trough-like passage which at a first longitudinal portion and at a second longitudinal portion opens upwardly toward and into the upper chamber portion of the combustion chamber, means for projecting through said trough-like passage longitudinally thereof a blast of burning mixture of fuel and combustion air in close proximity to said wall surfaces so as to heat them to incandescence; baffle means in said second portion of the pas- 17 sage for upwardly deflecting said blast into the upper combustion chamber portion through said second portion of the passage after the blast has travelled a distance through said passage; said upper chamber portion having at the central region thereof flow directing and combustion promoting means including upwardly and outwardly inclined lower wall elements located and arranged below and relative to the top closure of the upper chamber portion to aflord lateral passage for the deflected blast and combustion products at the upper end of said upper chamber portion so as to traverse the latter and thence to flow downward back toward the first portion of the trough-like passage in a closed vertical loop past said flow directing means, means including the flow opening between the chamber body and said first portion of the trough-like passage for causing products of combustion of the deflected blast so to flow across and from said upper chamber portion back into said trough-like passage through said open first portion thereof and laterally of the undeflected portion of the blast whereby to cause products of combustion so re-entering said passage to be guided by said wall surfaces into contact with said undeflected blast portion and part of said reentering products to travel with such blast portion in contact therewith and along and in contact with said wall surfaces to said upwardly deflecting baffle means whence to cause said part to be recirculated through said upper combustion chamber portion; and elongate passage means opening from said first longitudinal portion of the trough-like passage for discharging products of combustion including said recirculated part thereof from said passage, said discharging means being generally parallel to and below the trough-like passage and at a location therealong spaced from the blast projecting means for thereby forcing such products of combustion to flow from the upper to the lower side of the undeflected blast portion in the first longitudinal portion of said trough-like passage and over and in contact with said wall surfaces and in contact with the blast portion in said first passage portion and so as to be subject to ejector discharge at the base chamber portion below and in general parallelism with said trough-like passage.

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