US2606546A - Smoke generator - Google Patents

Description

Aug- 12, 1952 c. s. MCMULLEN 2,606,546

SMOKE GENERATOR Filed Deo. 25. 194'? 5 sheet-sneet 1 f ATTORNEY Aug 12, 1952 c. s. MGMULLEN SMOKE GENERATOR 3 Sheets-Sheet 2 Filed Deo. 25, 1947 lNvENToR CzadS/llwalkn/ ATTORNEY 5 Sheets-Sheet 5 INVNTOR awMCH/mm BY y ATTORNEY c. s.' MCMULLEN SMOKE GENERATOR Aug. 12,1952

Filed Dec. 25 1947 Patented Aug. 12, 1952 UNITED STATES PATENT OFFICE SMOKE GENERATOR Claud S. McMullen, New York, N. Y., assignor to National Smokehouse Equipment, Inc., Clifton, N. J., a corporation of New Jersey Application December 23, 1947, Serial No. 793,502

(Cl. 12S-59.5)

6 Claims. 1

This invention relates to a'srnoke generator for use in producing smoke for the smoke curing and preserving of comestibles such as meat or fish.

Smoke generators heretofore available have operated on the principle of supplying to a relatively deep bed of sawdust an amount of air insuicient to support combustion of the sawdust and causing the sawdust to smolder to generate the smoke which, after washing, if desired, is fed to the smoke houses. These generators produce smoke of varying density with consequent variation in the color or other properties of the comestibles cured or preserved by treatment therewith. Furthermore, such generators require frequent attention and convert only a minor portion of the sawdust to smoke, the remainder ci the sawdust being required for combustionpurposes. Moreover, such generators are relatively inflexible, i. e., they can be operated at full capacity or not at al1. In those cases in which a smoke generator is employed to supply smoke for a plurality of smoke houses and for some reason it is desired to supply smoke to only some of the houses, the iniexibility of the smoke generator presents a serious problem. Usually the smoke generator is run at its full capacity and the smoke supplied to the smaller number of smoke houses; under these conditions comestibles are subjected to a correspondingly greater volume of smoke with consequent deleterious effect on the product and uneconomic utilization of the sawdust employed to produce the smoke.

It is an object of this invention to provide a smoke generator for producing smoke for treatment of comestibles which generator produces a uniform volume of substantially constant density smoke, can readily be adjusted to produce any desired volume of such smoke or to produce smoke of different density, if desired, requires a minimum of attention by the operator, is compact and simple in design and efficient in operation.

Other objects and advantages of this invention will be apparent from the following detailed description thereof.

In accordance with this invention, a controlled miount of relatively cool moist sawdust is fed on to a grate or other support to form a relatively thin layer of sawdust thereon and a blast of air or other oxygen containing gas is introduced into contact with this thin layer of sawdust to consume the sawdust substantially at the same rate as it is fed on to the support, thus continuously generating a uniform volume of smoke per unit weight of sawdust fed on to the support. The amount of oxygen containing gas thus contacted with the sawdust is in excess of the stoichiometric amount required to support combustion thereof.

In accordance with a preferred embodiment of the invention, the smoke generator comprises an oblong housing. At one end of this housing disposed in side'by si'de relationship are a sawdust receiving compartment and a smoke generator compartment. These compartments extend almost the full length of the oblong housing and occupy the major portion of the volume of the housing, the sawdust receiving compartment being the larger of the two to provide a substantial s-torage of sawdust. The sawdust receiving compartment is suitably insulated so that the sawdust therein is not heated by the heat generated within the smoke generating compartment but is maintained in cooled moist condition in which condition it is fed continuously at a controlled rate to the smoke generating compartment. The smoke generating compartment contains a grate on to which sawdust is fed from the sawdust receiving compartment. A ilue extends the full length of the smoke generating compartment near its top for receiving the smoke generated.

At the other end of the oblong housing are disposed in side by side relationship a smoke receiving passage communicating with the flue and a settling out and cooling passage communicating with the smoke receiving passage. A fan is provided for exhausting smoke from the smoke receiving passage and introducing it into the settling out and cooling passage. provides the forced draft which causes atmospheric air to flow under relatively high velocity into contact with the sawdust to generatesmoke as hereinabove described, which smoke iiows through the flue, the smoke receiving passage and the fan, and is pumped by the fan into and through the settling out and cooling passage into the smoke discharge port at the exitend of the latter passage. A spray of water is fed to the fan and serves to keep the fan shaft and bearings cool and to quench any sparks which may be carried off by the smoke into the fan. This water is broken up into ne particles by the fan, which particles are dispersed in the stream of smoke to cool the smoke stream. The fan also communicates with a channel leading into the atmosphere. This channel and that connecting the fan with the smoke Yreceiving passage are each provided with a damper which may be controlled manually or automatically to regulate the amount of air mixed with the smoke to produce a smoke This fan also stream of any desired density. The stream thus produced is introduced into the settling out and cooling passage. In its fiow through the settling out and cooling passage tarry material and other suspended material are removed from the smoke stream, settle into a body of water maintained at the base of this passage, and are flushedV out of the smoke generator.

In the accompanying drawingsforming a part of this specification and sh-owing for purposes of exemplication a preferred form of this invention without limiting the claimed invention to such illustrative instance:

Figure 1 is a perspective viewof a smoke generator embodying this invention;

Figure 2 is a plan view of the generator shown in Figure l;

Figure 3 is a vertical section taken in a plane passing through line 3-3 on Figure 2;

Figure 4 is a vertical'section, partly in elevation, taken in a plane passing through line 4-4 on Figure 2;

Figure 5 is a horizontal section taken inrplanes passing through line 5-5on Figure 3;

Figure 6 is a vertical section taken in a plane passing through line 6-6 on Figure 3; and

Figure 7 is a fragmentary vertical section taken in a plane passing through line 'I-'I on Figure 4.

In the drawing I indicates an oblong housing f consisting of a front wall II, back wall I2, and end walls I3 and-I4, desirably of cast iron or steel or other suitable material. This housing is supported on suitable legs I desirably positioned at each of the corners thereof. The front and rear pairs of legs, viewing Figure 1, rest on and desirably are bolted or otherwise secured to channel irons I6 and I1, respectively, which impart rigidity to the leg support for the housing and carry the entire Weight of the generator.

Disposed at one end of the housing in side by side relationship are a sawdust receiving compartment I8 and a smoke generating compartment I9 (Figure 3). Both of these compartments, as shown in Figure 5, extend from end Wall I4 of the housing to an intermediate wall and occupy a major portion of the volume of the housing. The top of the sawdust receiving compartment I8 extends across the full width of the housing I0, is provided with a charging opening 22 normally closed by cover 23 equipped with a handle 24 through which opening 22 sawdust may be supplied to compartment I8.

The base of the sawdust receiving compartment I8 is defined by an inclined shelf 25 and a semicylindrical section 26. Wall 21 separates the sawdust receiving compartment I9 from the smoke generating compartment I9 and is made of suitable high temperature heat insulating material such as asbestos cement. A longitudinally extending narrow slot or opening `29 places the sawdust receiving compartment I8 in communication with the smoke generating compartment I9.

Feed of the sawdust through feed slot 29 is acomplished by a cylindrical drum 30 mounted on a shaft 3l. Drum 30 has approximately 180 of its peripheral surface removed to form an opening 32 which when in the position shown in Figure 3, permits the sawdust to enter the drum. A flange or extension 33 extends above the periphery of the drum the full length thereof. This flange, when the drum is rotated, serves to agitate the cool moist sawdust in compartment IB insuring -iiow of thev sawdust into the interior of 4 drum 30 through opening 32. As the rotation of the drum is continued in the direction indicated by the full line arrow on Figure 3, ange 33 moves through semi-cylindrical section 26 with very little clearance between it and the wall of section 25, forcing a layer of sawdust through feed opening 29. In the operation of this feeder a constant amount of sawdust is fed through opening 29 per revolution of drum 30. If it is desired to change the amount of sawdust fed to the smoke generating compartment I9, it is only necessary to change the rate of rotation of drum 30.

Shaft 3l of drum 30 is mounted for rotation in suitable bearings in walls I4 and 20 defining the opposite end walls of the sawdust receiving and smoke generating compartments. Rotation of this drum may be effected by any suitable driving mechanism, for, example that shown in Figure 2 involving a bevel gear 34 keyed to shaft 3| and meshing with a bevel gear 35 on a shaft extending from reducing gear box 36. A motor 31 drives this shaft through suitable reduction gears disposed in box 36.

The smoke generating compartment I9 desirably has a rebrick top wall 38, a rebrick lined side wall 39 and a firebrick portion 40 in alignment with heat insulating wall 2l as shown in Figure 3. A grate 4I is suitably supported on rebrick supports in the base portion of compartment I9 just below opening 29 as shown in Figure 3. This grate may consist of a flat metal plate provided with a number of elongated slots 42 which as shown in Figure 5 are arranged in three parallel rows, the slots of one row being staggered with respect to those of a contiguous row. The number and size of such elongated slots should be such as to provide a high velocity of air therethrough in contact with the relatively thin layer of sawdust supplied to grate 4I by the hereinabove described sawdust feed. A smoke receiving flue 43, desirably metal lines, is positioned at the top of the smoke generating compartment I6 and has an opening 44 running the full length thereof through which smoke generated in compartment I6 enters the flue 43. This flue conducts the smoke generated in compartment I6 to a smoke receiving passage 49 hereinafter more fully described and also provides a confined path which communicates with the smoke generating compartment through opening 44. Fan 6I hereinafter described exerts a suction through this path causing air to enter through slots 42 to support combustion of the sawdust fed on to grate 4I.

Disposed in the front wall II just above grate 4I is a cleanout door 45 which when removed gives access to the top of the grate and the feed opening 29. Suitable supports 46, desirably angle irons, are fastened to the base 47 of the housing and are arranged to removably receive an ash pan 48 into which fall the ashes from grate 4I. This ash pan is readily removable so that the ashes may be dumped and the pan replaced, when desired, on the supports 46.

Flue 43 communicates with a smoke receiving passage 49 desirably positioned at the opposite end of housing I0 from that containing the compartments I3 and I9 as shown in Figure 5. A bale 50 (Figures 4 and 6) extends downwardly from near the top of passage 49 across the inlet port 5I with which flue 43 communicates. This baille deiiects the smoke in a downward direction and` causes it to flow rst toward the base of passage 49 and then upwardly therethrough.

A cleanout opening 52, normally closed by a door 53, is provided just above the oor or base of passage 49. Suspended material carried by the smoke stream and settling out therefrom due to change in direction of flow caused by baffle 50 may be removed from time to time, as desired, through opening 52.

A bearing standard 5d is bolted 'or otherwise secured to the top of housing Il! as at 55. Fan shaft 56 is rotatably mounted in bearing 5T carried by this standard. This fan shaft may be driven through a belt or chain and sprocket drive 58 disposed in a removable housing or guard 59 and actuated by the drive mechanism hereinabove described. This fan is disposed within a housing 62 provided with one passageway 53 (Figure 6) connecting the fan with passage 49, a second passageway 6d communicating with the atmosphere, and a third passageway 65 (Figure 4) leading from the base porh of desired density. For any given adjustment cf dampers Si and tu, a smoke of constant deiinite density is produced, as will be pointed out more fully hereinafter. If it is desired to change the density for any reason, this is accomplished by changing the setting of dampers fil and 68.

A water spray or jet ill is positioned to discharge water onto the fan bearings as shown in Figure 6. The water thus serves to cool the ian bearings and is dispersed in fine drops by the fan blades into the smoke stream flowing through the fan housing functioning to partially cool this smoke stream. Jet 'Eil is supplied by water from a line l! (Figure l) having a valve l2 therein, provided with a threaded coupling i3 for connection to any suitable water line, a second valve i4 controlling flow throughl a branch 'l5 leading into a water sump 16 (Figure 4) disposed at the base oi the settling out and cooling passage 55.

A steam jet i is disposed in the passageway 3 and may be turned on when the temperature of the smoke is too low, say below 120 F., to introduce steam to raise the temperature to the desired value. Desirably steam jet i5 and water by well known throttling type thermostat controls lld and iilb (Figures l and e) located at the top of passage 65. If the temperature of the smoke entering passage 5S is too high, the water and steam iet valves are operated to control the ilow of these media so that the temperature of the smoke entering passage 55 is maintained at the desired constant value. Thus, for example, should the temperature of the smoke rise, more cooling water is admitted through jet i and should the temperature fall below the desired value, steam. is turned on, or more steam admitted through jet lu'. Since the controls 10a and 'mh may be of any well known type, further description thereof is considered unnecessary.

A baule 'il is disposed in passage 65 vsubstantially parallel to wall 'i8 separating the smoke receiving passage il@ from the settling out and cooling passage 55. A second baffle 'I9 extends at right angles to barile il from wall l2 dening a 6 side wall of passage 5B. Baies 11 and lg Cause the smoke stream to flow through a tortuous path in its passage through 66, the smoke stream rst flowing vertically downwardly, then horizontally at right angles to its initial direction under baiile 17, then vertically through the space between baiiles 'I1 and 19 into the port 8B leading from the exit end of the settling out and cooling passage 66. As the smoke stream changes its direction of flow, contacts baille '19, and is caused to pass through the restricted passageway 8l between baffles Tl and 19, tarry material, sui.- pended liquid and solid particles are removed therefrom, the material thus removed gravitating into the sump 16.

Water is continuously supplied to sump 'i5 by branch line 15 to provide a stream of water flowing over the partitions 82 (Figures 4 and 5) in the corner of the passage 65. Partitions S2, with the corner of housing ill, form a drain box 83 over the top of which water containing tarry and other suspended material continuously flows. Near the base of the drain box, in the base of side wall i3, is an opening 84 (Figure 7) through which the water flows into a drain box 85 provided with an overflow 8S. Box 85 is dimensioned such that a column of water is maintained therein of a height to provide a liquid seal for opening 3d, which lseal adequately prevents escape of smoke through opening 8.

It will be noted from Figure 5 that the sawdust containing compartment I8 and the smoke generating compartment are disposed in side by side relationship at one end of housing lil and extend from this end the major portion of thel length of the housing. The smoke receiving passage i9 and the smoke settling out passage E56 are disposed in side by side relation at the other end of housing Iii occupying the remaining minor portion of the volume of the housing. Passage @9, as clearly shown in Figure 5, is disposed in longitudinal alignment with compartments El and 65 in longitudinal alignment With compartment i8; the top of compartment i9 through.

port 5l communicates with passage 4Q; the top of passage 4! through fan 5i communicates with passage E6; and smoke discharge Dort 86 is disposed at the exit end of passage 65. Hence a compact and simple smoke generator is provided having a long tortuous path of travel for the generated smoke to effect cooling thereof and removal therefrom of suspended material, including water added for cooling purposes. Further, the fan (a) furnishes the draft for providing a blast of air to support combustion of the sawdust, (b) draws the resultant smoke through the iiue i3 and smoke receiving passage 49, (c) effects mixing of the smoke with air in proportions to produce a smoke of desired density depending upon setting of dampers 6l and 58, (d) disperses cooling water into the smoke stream, and (e) forces the resultant smoke stream through settling and cooling chamber 66 into and through discharge port Se which communicates with one or more smoke houses.

In operation, cool moist sawdust is charged into compartment i8. The moisture content of the sawdust will depend on the nature of the so dry that the individual particles readily-sepa-` rate when pressed, water should be added thereto acoge-4e 7. and' the sawdust and water mixed to produce a moist mass, i. e., one from which water will not drainoif but isV suiciently moist so that the particles when pressed between the fingers tend to lump or agglomerate. Motor 31 is then energized to feed the sawdust in regulated amounts onto grate. 4|, thev sawdust on this grate having previously been ignited. Motor 6B: is energized at the same time to actuate fan 6| to cause a blast of air to pass through. slots 42, the slot arrangement. giving effective distribution of air into contact with the thin layer of sawdust. on grate 4|. The rate of air blast and sawdust fed is such that the sawdust is transformed into smoke at substantially the same rate as. it is fed by drums. through slot 29. The smoke thus generated flows through ue 43, first down and then. up through passage 49 into passageway 63 where it mixes with air drawn into passageway 63 through passageway 64 by fanr 6I to produce a smoke stream of desireddensity. The resultant smoke stream, if too hot, is cooled by water dispersed therein by the fanY 6l and if too cool, is warmed by steam admitted through 'lil'. and then flows through the. tortuous path in passage 66 exiting through discharge port Bd after tarry material, moistureY and other suspended material has been removed therefrom. The above described operation. is continuous, sawdust in chamber I8 being replenished when necessary.

If it is desired to reduce the amountof smoke generated, this is accomplished by` reducing the speed of rotationof drum Sil'and, if desired, of fan 6l, the motors driving these units being variable speed motors so that they can drive the drum and fan, respectively, at any selected speed. Thesev two motors, the drum 39 and fan 6l are designed so that for a given. speed of the motor driving drum 30A and a correlated speed of the motor driving fan 6|, a blast of air providing oxygen inexcess of the stoichiometric amount required. to support combustion of the thin layer of sawdust maintained-'on grate 4! is supplied to this grate. Once combustion of this thin layer is initiated, theblastof air initially contacting the sawdust particles, due tothe arrangement of slots 42V in grate 4l, causesa minor portion of the sawdust to burn, generating high temperatures instantaneously which effect liberation of the volatile constituents of the sawdust, producing a maximumy amount'of smoke per unit vweight of. sawdust consumed.

It will be noted the. processof this invention results in the production of 1a uniform volume of smoke per unit weight ofv sawdustv consumed, which smoke is of. constant density, and that the density of the smokeV can be changed, if desired. It will be further noted. the smoke generator embodying this invention is unusually flexible inthat the volume of smoke generated canreadily be changed by manipulating thecontrols. for the motors driving the sawdust feed and the fan, requires-.a minimum of attention by the operator, and is compact andV simple in design and eicient in operation.

The term sawdust is used herein in a broad sensefand is intended to include woodchips and chips or dust of' other cellulose material suitable for use in generating smokeY for heating comestibles.

Since certain changes in carrying out the above process and in the smoke generator, which embody the invention, may be made without departing from its scope, it is intended that al1 matter contained in the above description or shownv in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

Whatfis claimed is:

1. A smoke generator comprising a sawdust receiving compartment, a smoke generating compartment disposed contiguous to the sawdust receiving compartment, a grate in the smoke generating compartment, means in the sawdust receiving compartment for feeding sawdust therefrom in controlled amounts on to said grate, a flue in the topv of the smoke generating compartment extending substantially the full length thereof and communicating therewith, a smoke receiving passage communicating with said flue, a settling out and cooling passage disposed adjacent the smoke receiving lp-assage, a fan communicating with both of said passages for exhausting smoke from the smoke receiving passage and for introducing the smoke into the settling out and cooling passage, and a smoke discharge port at the exit end of the settling out and cooling passage.

2. A smoke generator comprising a sawdust receiving compartment, a smoke generating compartment disposed contiguous to the sawdust receiving compartment, a grate in the smoke generating compartment, means in the sawdust receiving compartment for feeding sawdust therefrom in controlled amounts on to the grate in the smoke-generating compartment, a flue in the top of the smoke generating compartment extending substantially the full length thereof and communicating therewith', a smoke receiving passage having an inlet port, said flue leading into said inlet port of said smoke receiving passage, a baie in said smoke receiving passage disposed in front of and extending below said inlet port to causethe'smoke to flow rst downwardly in said smoke receiving-passage and then upwardly therethrough, a settling out and cooling passage disposed adjacent the smoke'receiving passage, a fan communicating with both of said passages for exhausting smoke from the smoke receiving passage and for introducing the smoke into the settling out and cooling passage, and a smoke discharge .port at the exit end of the settling out and cooling passage.

3. A smoke generator for producing smoke for treatment of comestibles comp-rising an oblong housing, a sawdust receiving compartment, a smoke generating compartment, said compartments being disposed in side by side relationship at one end of said housing and occupying a major portion of the volume of said housing, said compartments being in communication with each other through a narrow elongated slot disposed in a wall separating said compartments, a grate in the smoke generating compartment disposed beneath said narrow elongated slot, means in the sawdust receiving compartment for feeding a regulated amount of sawdust from said compartment through said slot on to said grate, av

smoke receiving passage having an inlet port, and a settlingout and cooling passage disposed in side by side relationship therewith at the other end of said housing and occupying the remainder of the volume of said housing, a flue in the top of and extending the length of the smoke generating compartment and communicating therewith and also with said inlet port to the smoke receiving passage, a lbaiiie in the smoke receiving passage disposed in front of and extending below said in- `let portto cause the smoke to ow first downwardly in said smoke receiving passage and then upwardly therethrough, a Vfan communicating with both of said passages for exhausting smoke from the smoke receiving passage and or introducing the smoke into the settling out and cooling passage, and a smoke discharge port at the exit end of the settling out and cooling passage.

4. A smoke generator for producing smoke for treatment of comestibles comprising an oblong housing, a sawdust receiving compartment, a smoke generating compartment, said compartments being disposed in side by side relationship at one end of said housing and occupying a major portion of the volume of said housing,

said compartments being in communication with each other through a narrow elongated slot disposed in a wall separating said compartments, a grate in the smoke generating compartment disposed beneath said narrow elongated slot, means in the sawdust receiving compartment for feeding a regulated amount of sawdust from said compartment through said slot on to said grate, a smoke receiving passage having an inlet port, and a settling out and cooling passage disposed in side by side relationship therewith at the other end of said housing and occupying the remainder of the volume of said housing, a nue in the top of and extending the length of the smoke generating compartment and communicating therewith and also with said inlet port, a baliie in the smoke receiving passage disposed in front of and extending below said inlet port for causing the smoke to flow first downwardly into said smoke receiving passage and then upwardly therethrough, a fan communicating with both of said passages for creating a draft through the grate and for exhausting smoke from the smoke receiving passage and introducing said smoke into the settling out and cooling passage, and a smoke discharge port at the exit end of the settling out and cooling passage.

5. A smoke'generator for generating smoke for treatment of comestibles, which comprises an oblong housing, a sawdust receiving compartment and a smoke generating compartment disposed in side by side relationship and extending from one end of said housing to near the opposite end thereof across the full width thereof, high temperature heat insulation on the inner walls of said smoke generator compartment to minimize the transfer of heat therefrom to the sawdust in the sawdust receiving compartment, the side wall separating the sawdust receiving compartment from the smoke generating compartment having an elongated slot 'therein through which the two compartments are in communication with each other, said slot being disposed near the base of the sawdust receiving compartment, a grate in the smoke generating compartment disposed below said slot, a cylinder having a substantial area of its periphery open rotatably mounted in the lower portion of said sawdust receiving compartment arranged to receive sawdust, means for rotating said cylinder to cause sawdust to be fed in regulated amounts through said slot on to said grate to form a thin layer of sawdust on said grate, a nue extending the full length of said smoke generating compartment at the top thereof and communicating therewith, a smoke receiving passage having an inlet port, and a settling out and cooling passage disposed in side by side relationship therewith at the other end of said housing, the exit end or" said flue leading into said inlet port, a baiile in said smoke receiving 'passage disposed in front .of and extending below said inletV port tofcausesmoke nowing from-said flue to flow rst in a downward direction then .in an upward direction about said baie through said smoke receiving passage, a fan communicating with both of said passages for creating a draftl of air through 4Said grate to support combustion of the sawdust supplied thereto and forV exhausting the resulting smoke through said flue and into and through said smoke receiving passage and introducing the smoke into the settling out and cooling passage, means for supplying water to the fan bearing and fan Ablades to cool the fan bearings, the rotating fan blades dispersing said water into said smoke, awater sump for collecting tarry material and suspended particles removed from the smoke disposed at the base of the settling out and cooling passage, and a smoke discharge port at the exit end of the settling out and cooling passage.

6. A smoke generator for generating smoke for treatment of comestibles, which comprises an oblong housing, a sawdust receiving compartment and a smoke generating compartment disposed in side by side relationship and extending from one end of said housing to near the opposite end thereof across the full width thereof, high temperature heat insulation on the inner walls of said smoke generator compartment to minimize the transfer heat therefrom to the sawdust in the sawdust receiving compartment, the side wall separating the sawdust receiving compartment from the smoke generating compartment having an elongated slot therein through which the two compartments are in communication with each other, said slot being disposed near the base of the sawdust receiving compartment, a grate in the `smoke generating compartment disposed below said slot, a cylinder having a substantial area of its periphery open, said cylinder being rotatably mounted in the lower portion of said sawdust receiving compartment, an extending portion on said cylinder running substantially the full length thereof, means for rotating said cylinder to cause sawdust to be fed in regulated amounts through said slot on to said grate to form a thin layer of sawdust on said grate, a nue extending the full length of said smoke generating compartment at the top thereof and communicating therewith, a smoke receiving passage having an inlet port, and a settling out and cooling passage disposed in side by side relationship therewith at the other end of said housing, the exit end of said ue leading into said inlet port, a baie in said smoke receiving passage disposed in front of said inlet port and extending therebelow to cause smoke flowing from said nue to iiow first in a downward direction then in an upward direction about said bae through said smoke receiving passage, a fan, a channel connecting said fan with said smoke receiving passage, said fan being also connected with said settling out and cooling passage for creating a draft of air through said grate to support combustion of the sawdust supplied thereto, for exhausting the resultant smoke from said flue and said smoke receiving passage and introducing the smoke into said settling out and cooling passage, a second channel connecting said fan with the atmosphere, a damper in each of said channels to regulate the relative proportions of air and Vsmoke suppliedby .said 1fan to .-said settling'out Handcoolingmassage, means rfor supplying Water 4vtothefzam bearings and fan fbladesto 'cool 'the tan bearings; the rotating fan blades .dispersng 'said :waterinto vsaid smoke, 1a Water sump for collecting tai-ry material fand suspended par- `izioles removed from saidfsmoke disposed at the ibase .of the .settling out and cooling passage, and a: smoke discharge port at the exit 'end lof `the ysettling out and--coo1ing passage.

CLAUD JS. .MCMULLEN.

12 REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 207,268 Goodin Aug. 20, 1878 '1,644,693 Robertson. Oct. 11, 1927 2,072,364 Gray et a1. Mar. 2, 1937 10 2,2233597 Brewster Dec. 3, .1940

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