US2866627A - Space heaters and driers - Google Patents

Description

Dec. 30, 1958 R. M. SHERMAN SPACE HEATERS AND DRIERS 5 Sheets-Sheet 1 Filed Jan. 8, 1957 liweazi'or lllllllll llllll Dec. 30, 1958 R. M. SHERMAN 2,355,627

SPACE HEATERS AND DRIERS Filed Jan. 8, 1957' 5 Sheets-Sheet 2 122042231302 RaZZci'ow MSW by Qua /5 W VWLLZW v- Dec. 30, 1958 R. M. SHERMAN 2,866,627

SPACE HEATERS AND DRIERS I Filed Jan. 8, 1957 5 Sheets-Sheet 5 Dec. 30, 1958 R. MTSHERMAN 2,866,627

SPACE HEATERS AND DRIERS Filed Jan. 8, 1957 I 5 Sheets-Sheet 4 Dec. 30, 1958 R. M. SHERMAN SPACE HEATERS AND DRIERS 5 Sheets-Sheet 5 Filed Jan. 8, 1957 vSPACE HEATERS AND DRIERS Rallston M. Sherman, Glastonbury, Conn., assignor to The Silent Glow Oil Burner Corporation, Hartford, Conn., a corporation of Connecticut Application January 8, 1957, Serial No. 633,070 1 12 Claims. (Cl. 263-19) My invention relates to fluid fuel burning apparatus, for example, space heaters and driers employing fluid fuel such as oil.

The invention has among its objects an improved way of burning the fuel.

Another object of the invention is a space heater and drier having provision for burning the fuel under pressure in a drum-like combustion chamber the walls of which are provided with relatively closely spaced, small perforations for escape of the combustion products which when they so escape mix with a blast of air in contact with the walls of such chamber for producing a hot gaseous medium which is projected into the space to be heated or against a surface of the like to be dried.

The above and other objects of the invention, however,

will be best understood from the following description when read in the light of the accompanying drawings of an embodiment of the. invention selected for illustrative purposes, while the scope of the invention will be more particularly pointed out in the appended claims.

In the drawings:

Fig. 1 is a side elevation of a portable space heater and drier according to the invention;

Fig. 2 is a side elevation of the space heater and drier according to Fig. 1 as viewed fro-m its side opposite that shown by Fig. 1;

Fig. 3 is a section on the line 33 of Fig. 5, parts in elevation and parts omitted;

Fig. 4 is a section on the line 4-4 of Fig. 1;

Fig. 5 is an end elevation of the space heater and drier according to Fig. 1 as viewed from the left;

Fig. 6 is a section on the line 6-6 of Fig. 1;

Figs. 7 and 8 are sections on the lines 7-7 and 8-8, respectively, of Fig. 6 on an enlarged scale; and

Fig. 9 is a section on the line 9-9 of Fig. 3 on an enlarged scale.

Referring to the drawings, the space heater and drier illustrated comprises an elongated cylindrical oil tank 1 which adjacent one of its ends is provided with opposite wheels 3 and adjacent its other end with opposite legs 5. These wheels and legs are adapted to rest upon the floor F. As shown, the end of the tank adjacent the legs is provided with a handle 7 so that the legs may be raised from the floor while the wheels still rest upon it, thus enabling the apparatus readily to be wheeled about by use of the handle.

Above the oil tank 1 in spaced parallel relation thereto is shown an open ended, cylindrical, sheet metal shell with or casing 9. As illustrated, the shell is permanentlysupported on and secured to the tank by pairs of posts 11 at opposite ends, respectively, of the shell, which parts are welded at one of their ends to the shell and at their opposite ends to the tank.

As illustrated, within the shell 9 adjacent one end thereof and coaxially therewith is positioned a cylindrical drum 13 forming a combustion chamber in which the heating fuel is burned. The drum, which is formed of relatively thin, heat refractory, sheet metal, for example States Patent 0 F 2,866,627 Patented Dec. 30, 1958 stainless steel about 0.03 inch thick, has the lateral wall 15 and opposite end walls 17 and 19. As shown, the end wall 17 has an outturned peripheral flange 21, while the end wall 19 is provided with an inturned peripheral flange 23, these flanges being welded to the lateral wall 15 of the drum.

In accordance with the invention the wall of the drum 13 is provided with an area or areas of relatively closely spaced small perforations 25. The perforated area or areas may be confined to the lateral wall of the drum or to the end wall 17 thereof or may be included as part or parts of the extent of both of said walls. In all of these cases, although the perforated area may be coextensive with the wall, it need not necesarily be so. For example, particularly when a high pressureis to be maintained in the drum as hereinafter more fully explained, the lateral wall may have one or more bands constituting the perforated area or areas thereof, say a single band at about the center portion of the length of the drum, or say two bands about equally spaced from each other and the ends of the drum, while the end wall 17 may have one or more ring-like bands of perforations concentric with thedrum axis or have a single centrally positioned perforated area, in all of these cases the remainder of the wall in respect .toits perforated area or areas being imperforate.

As shown, the drum 13 is supported adjacent its opposite ends on brackets 29 (Figs. 3 and 9) carried interiorly of the shell 9. Each of these brackets, as illustrated, has an arcuate portion 31 which at opposite ends has legs 33 terminating in feet 35, the latter being welded to the shell. At its left hand end, as viewed in Fig. 3, the drum carries an angle clip having a vertical leg'37 welded to the outer side of its end wall 19 and a horizontal leg 39 which hooks under the arcuate portion 31 of the adjacent bracket 29. At the opposite end of the drum the arcuate portion 31 of the adjacent bracket 29 has welded to its under side the horizontal leg 41 of an angle clip provided with a downwardly projecting leg 43. Removably secured to this vertical leg by a bolt 45 is the vertical leg 47 of a second angle clip having a horizontal leg 49 which hooks over the flange 21 of the adjacent end Wall 17 of the drum. In an obvious manner by this construction the drum is removably secured within the shell.

Co-axially with the opening 27 in the end wall 19 of the drum at the outer side of said wall is positioned an open ended blast tube 51. This tube, as shown, is secured to said end wall by angle clips 53 welded to said wall and said tube.

As illustrated, within the blast tube adjacent the opening 27 in the end Wall 19 of the drum and coaxially with said opening is positioned an oil atomizing nozzle 55 carried at the end of an oil supply pipe 57, which latter projects from the opposite end of the blast tube, this pipe beingcarried by a bracket 59 positioned internally of the blast tube and secured thereto by bolts 61. Positioned adjacent the nozzle 55 are a pair of ignition electrodes 63 extending through insulating bushings 65 secured to the end terminals 69 adjacent the rearward end of the blast tube. Also carried by the pipe 57 is a plate formedto present an annular series of inclined vanes 70 which act to cause whirling of the combustionjair discharged by the blast tube into the drum so as to pro-mote admixture of such air with the oil sprayed from the nozzle 55. For causing an ignition spark between the electrodes their terminals 69 are shown as connected to leads '71 (Figs. 3 and 6) from the secondary of a transformer 73', which latter is mounted'upon a plate 75 (Fig. 2) carried adjacent one of its ends by one of the posts 11 and adja I cent its opposite end by a like auxiliary post 76.

,Asturther illustrated, the shell 9 istp'rovided at its member; 1

upperuportiouwitha rearward extensions, ofarcuate transverse cross-section, removably secured to the shell by screws 79 (Fig. 2), the" arcuate cross-section of the extcminn pmviding it with :an openrbottom. 7:.

Extending xupwardly. from the oil tank: and carried thcrebyjs shown .a-post. 8.1 which .at its upper end. carries a platiormfiSmponrwhich rests and to which is :secured the: basc.;.of:.an electric motor 85 thegshaft of which is positioned coaxially of the shell 9. Projecting-laterally from :the post ;81 i$ an arm 87 having at its outer end a sleeve 89 through which extends and -to which is emovablyysecurcdthe extension 91 of the casing '93 of anoil pump .95 The shaft 97of theelectric motor-85is shown i tlflrryingla beltpulley 99 about whicha belt pulley-101 carried by, the drivingshaft 103-ofthe pump. passes a belt 105 for driving the pump. As indicated, :the pump haste suction pipe 107. (Fig. 1). extending into the .oil tank, inwhich pipe ;is insertedlanoil filter 108. The pump has a dischargqpipe 109 1(Fig.. 4) leading ,to an oilfilter .111. tFromthe filter .111 the oil is forced through a pipe 113, connected to therearwardend of thepipe 57, which latter at its forward end carries theoil atomizing nozzle 55. Thelputnn;v which is of known construction, is providedatits outlet with a relief valve (not shown) connected byga pipe 1-15.(Fig. 1) .for by passing part ;of.the Q Ldischarged from the pump back to the oil tank, this relieftvalve being manually adjustable for regulating the amount of oilsoby-passed so as automatically to control and maintain constant selected .pressures of the oil supplied the nozzle.

As shown, the shaft 97 of the electric motor 85 carries a fan 117 having the four fan blades 119. Within the 'shellin thespace between. the fan andthe entrance end of the blast tube 51 is positioned a sheet metal partition 121 the peripheral edge of which fits and is welded to the shell. ,Thispartition is providedwith a central opening123 coaxial. with the blast tube and drum, givingthe partition an annular shape. The fan blades 119are-of common construction, having portions wider adjacent the periphery of the fan than adjacent its hub, so that the bulk of theair dischaged from the fan is from these wider portionsof-the fan blades. In an operativesense this causes the bulk of the air to be discharged from the fan in the form of an annular blast of air:directed toward the partition 121.. The fan is of such diameter relative to the shell9 that this operatively annular blast of air lies adjacent the interior surface of the shell. partition-121 h of'such radial width that this annular blast. of air is directed againstit.

At the side of the partition 121 adjacent the fan are shown four radial vanes or battles 125 arranged in quartering relation and each extending from the axis of the shell outwardly, to its interior surface, these baffies being :Welded at their outer edges to the-shell, andto each other, at the axis; of ,theshell. The, operatively, annular blast .of :air from thefan which strikes the partitionis turnedtinwardly by ,it towardthe-axis of theshell and flows .towardaaid The annular axisin .thespaces between adjacent battles, 125, which its. entrance .endufor passage therethrough into the combustion chamber, with the result of increasing the pressure. within the combustion chamber overthat which would exist if the fan or any part thereof .dischargcddirectlytinto the blast tube. The air leaving the fan. tends stronglysto whirl about theaxial line 'of the fan, and the vanes orsbames prevent such whirling" of.the1 air flowing between them, which acts by converting the velocity head of the whirling to pressure head also to increase the pressure of theb last of air discharged into the blast tube 51.

As illustrated, the partition 121 is provided with an annular series of circular. openings 127, and between the partition and entrance end of the blast tube is positioned a ring-shaped plate .129 of the same radial width as the partition. The plate 129, as shown, is provided with an annular seriesof circular'opcnings 131,.and is rotatably mounted for moving these openings thereof more orless into registry with'the openings 127 of the partition. In otherwords, the plate 129 is adapted to .act as a damper for controlling the etfective cross-sectional discharge area of the openings 127 of 'thepartition.

The rotatable annular plate is held loosely against the partition by bolts 133 having heads 135 (Fig. 8) welded torthepartition. Theshanks of the boltsextend through arcuate slots 137 .inthe partition so that the plate may be rotated relative to it, the nuts 138 on the shanksof the bolts being prevented from turning by welding them to said shanks. As shown, adjacent its QuterJ eriphery the plate carriesan angle bracket 1'39. (Figs. 6 and 7) one leg ofwhich-liesagainst-the plate and is welded thereto and the 'otherleg of which lies adjacent the interiorsurfaceof the shell 9. Througha perforation; inlthe last mentioned legsand a short arcuateslot 141 extendingcircumferentially ofthe-shell (Figs. 1 and 71) projects the screw-threaded shankof a bolt 143 the head 145 of which is welded to that leg. Exteriorly of the shell the shank of the bolt carries a washer 1'47 and a thumb nut 149. in an obvious manner by-,loosening the thumb nut the plate 129 may berotated into adjustcdpositions-and held in such positions by again tightening the thumb nut.

Thebopenings 127 in the partition 121 are shown as aligned: with the annular .space 151 betweenthe lateral wall of the-drum .13 and the shell 9 so that a fraction of the operatively annular blast of air discharged from the fan passing. through said openings will be projected into and through that space. In passing. through such space the airsis heated by contact'rwith and heat radiated from the lateral wall of thedrum; Alsoif the lateral wall is provided with perforations 25 such air will mix with the gaseous products of combustion discharged through'such perforations and, if the end wall 17 of the-drum has per forations 25, will as it leaves the shell mix with the gaseous products discharged through them, whereby to form a hot gaseous medium which is projected beyond the shell. The strength of the blast passing through the openings .of the partition is augmentedby reason of the vanes or bafiles associated withthe partition preventing whirling. of the air'in theispaces betwcenrthe bafiles so that a strong-blast of hot gaseous medium is projected from the shell. By angular adjustment of the damper-plate 129 the fraction ,Q theoperatively annular blast of air projected by the fanlinto the spacelSl may be "adjusted relative to the fraction of said :blast which discharges through the central opening ,of the partition 121 into the drum, in that way selectively to vary the-degrec of pressure. within thedrum.

Mostofthe air which is projected through the central opening 123 of the partition 121 will be projected into the entrance end of the blast tube which is positioned close tothe partition. Any air passing through this opening which .doesnot enter the blasttube will be discharged intoand pass. through; the annular space 151 about the drum. Likewise air whichis projected by the central portions of the .fan bladeswill admix with theair flowin radially inward betweentthe, vanes -or bafiles .125 and be discharged through the central opening of thepartition.

In theabove construction by reason. of the fuel being burnedwithin the drum-like'combustion chamber under increased pressure it has been :found that the amount of fuehxburhed in Ta giventime in a given size combustion chamber may. be much -.i ncreased;: :Prefenablpthe iperforations 25' are as small as possible, about 0.08 inch diameter, for practical reasons in producing them economically, being their minimum size. To prevent the formation and discharge through them of smoke and dangerous amounts of carbon monoxide they should not be too large, transverse cross-sectional areas of about 0.018 square inch being their maximum permissible size. Also, to prevent the formation and discharge through them of smoke and dangerous amounts of carbon monoxide, it has been found that they should be distributed over the wall surface of the drum in such number as to present approximately from 0.05 to 0.14 square inch of total transverse cross-sectional area per square inch of perforated surface, such perforated surface, as above explained, not necessarily being confined to any one wall of the drum, or when confined to a single wall not necessarily being a continuous surface. Further, to prevent the formation and discharge through them of smoke and dangerous amounts of carbon monoxide, it has been found that provision must be made for securing a flame pattern within the drum such that the flame is in such proximity to the perforated portion or portions of the walls of the drum to heat at least those portions to incandescence but in out-of-contacting relation with such portion or portions so as to be separated from said portions by gaseous combustion products. Conveniently this flame pattern may be secured by proper design of the nozzle, and alternately, as explained in my co-pending application Serial Number 439,653, filed June 28, 1954, may be secured by use of a suitable shield adjacent the wall of the drum Where the fuel oil nozzle is positioned. Under these conditions by properly proportioning the amounts of air and fuel supplied the combustion chamber and the total cross-sectional area of the perforations to the cubic contents of the drum it has been found that complete combustion of the fuel will be secured and therefore with full assurance of total absence of discharge of smoke and carbon monoxide from the device.

In respect to the effect of pressure within the drum increasing the fuel burning capacity of the device it has been found that by having the total area of the perforated portion or portions of the walls of the drum so proportioned to the cubic contents of the drum that such area in square inches is arithmetically approximately from to 35 percent of the arithmetical value of the cubic contents of the drum expressed in cubic inches, and having the air, of the oil-air mixture being discharged into the drum, in amount sufficient to maintain in the drum, while combustion proceeds, a pressure of approximately from 0.025 to 0.2 inch of water above normal atmospheric pressure at sea level, fuel oil can be burned Within the drum under the above conditions at the high rate of one gallon per hour per 550 to 1600 cubic inches of the cubic contents of the drum, provided this pressure varies approximately directly and linearly with the amount of fuel oil within the range of fuel oil just specified. For example, a drum 9.5 inches in diameter and 12 inches long, having perforations about 0.08 inch in diameter uniformly spaced on inch centers and forming a perforated band at the center of the length of the drum presenting a total cross-sectional area of perforations about 18 percent of the arithmetical value of the cubic contents of the drum, will completely burn commercial No. 2 fuel oil at the high rate of one gallon per hour per 850 cubic inches of the cubic contents of the drum by supplying the air to the mixture in such amount as to maintain the pressure in the drum at about 0.13 inch of water above normal atmospheric pressure, all the walls of the drum being heated to incandescence throughout their entire extent. Other fuels such as commercial No. 3 fuel oil, kerosene, gasoline, and the like may be completely burned in the above way by observing the preEautions herein specified, the temperature secured be ing commensurate with the B. t. u. value of the particular fuel oil burned. It .will be understood in these con- 6 nections that increasing the amount of fuel oil burned within the drum results in its walls being heatedto a correspondingly higher temperature. However, it has been found that with pressures within the drum of less than approximately the 0.025 inch of water no substantial increase in the amount of fuel oil that can be burned is effected by varying the pressure, while with pressures above the 0.2 inch of Water the amount of air that must be supplied the mixture to maintain the pressure presents so much excess air in respect to the amount thereof necessary to support combustion that the temperatures secured are not commensurate from an economic standpoint with the concomitant increased amount of fuel oil that then can be'burned.

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

I claim:

1. A heater having, in combination, a drum combustion chamber having end and lateral walls, the lateral wall being formed witha multitude of relatively closely spaced small diameter perforations for discharge of gaseous combustion products, a casing extending about said lateral wall in spaced relation thereto for receiving said products, an open ended combustion air blast tube of lesser transverse cross-section area than that of said chamber opening into said chamber adjacent its axial line through one of its end walls, a fluid fuel nozzle associated with said blast tube for discharging fuel that mixes with such combustion air, a partition in said casing extending transversely thereof adjacent the entrance end of said blast tube, which partition is provided with an opening adjacent said axial line for discharging air into said blast tube; means for directing, against a portion of said partition that surrounds said opening thereof at that side thereof which is remote from said chamber, an operatively annular blast of air surrounding said opening;

bafiies associated with said partition operatively forming passages extending from said portion of said partition to said opening, which passages are of progressively decreasing transverse cross-section area as they approach said opening and are adapted to direct arcuate fractions of said annular air blast striking said portion of said partition to said opening for discharge therethrough into said blast tube and by reason of such progressively decreasing cross-sectional areas to increase the pressure of the air discharged from them into said opening, and means for projecting a blast of air through the space be tween said casing and the lateral wall of said chamber for admixture with the combustion products discharged into said space through the perforations of said lateral wall. a

2. A heater according to claim 1 in which the means for projecting a blast of air through the space between the casing and the lateral wall of the combustion chamber comprises openings, formed in that portion of the partition against which the annular blast of air impinges, for passage into said space of a portion of such annular blast. I

3. A heater according to claim 1 in which the means for projecting a blast of air through the space between the casing and the lateral wall of the combustion chamber comprises openings, in that portion of the partition against which the annular blast of air impinges, formed for passage into said space of a portion of such annular blast, and means for regulating the amounts of air discharged into said space and into said blast tube for regulating the pressure in said chamber.

4. A heater according .to claim 1 in which the means for projecting a blast of air through the space between the casing and the lateral wall of the combustion chamber comprises openings, formed in that portion of the partition against which the annular blast of air impinges, for passage into said space of a portion of such annular 7 blast, 'and mcans'operative'ly forming dampersassociated with said openings for regulating" the relative amounts of "air discharged therethrough andthrough thepassages formed by the bafiies, whereby to regulate the pressure in said chamber.

5. A heater according toclaiml in which' the means for projecting a blastof air through the space'between the casing and-the lateral 'wall of the combustion chamber comprises openings,-formed in that portion of the partition against whichthe annular blast of air impinges, for passagc 'into'said'space of'a portion of such annular blast, and a rotatably'adjusta'ble plateoperatively associated with said phrtitionand formedwith openings adapted by such adjustment to be placedmore or less inregistry with said openings'in"said-partition for regulating the amounts ofair dischargedthroughsaid openings in the partition anclthrough-thepassages formed by the batiles, whereby to regulate the pressure in said chamber.

6. A heater having, in combination, an open ended cylindrical outer shell, '21 cylin'drical drum'of less diameter and-shorter length 'than-said'shell positioned therein coaxially therewith, the lateral wall of said 'drum being formed with a multitudeof relatively closely spaced small diameterperforations for discharge of gaseous combustion products from said drum-into the annular space between said lateral wall and said shell for discharge through one of the ends of said shell, an open endedair blast tube within said shellopening at one of its ends into'the interior-of 'said drum adjacent its axial line through that end wall of said drum which is remote from such dis charge end of-said shell, a fuel oil atomizing nozzle adjacent the discharge end of said blast tube, means for supplying said nozzle with fuel oil under pressure, a fan positioned coaxially of said shell in spaced relation to the entrance end of said blast tube, said fan being of such diameter relative to the diameter of said shell that it discharges the bullc of the air'projected by'it asan annular air-streamadjacen't the interior wall surface of said shell toward said drum, a partition in-said shell extending transversely thereof in the space between said fan and entrance end of said blast tube, which partition is formed with an air discharge opening opposed to the entrance end of said blast tube for discharge of combustion air into said tube for admixture with the atomized fuel oil discharged from said nozzle, battles in the space between said fan andpartition'associated with the latter and extending radially of said'shell toward the opening of said partition, the spacings between said baffles decreasing as theysoextend operatively to formpassages which are ofprogressively decreasing cross-sectional areas as theyapproach the axis of said shell, which passages direct toward said opening arcuate fractions of said annular air stream projected by saidfan against said partition and by reason of said progressively decreasing crosssectional areas of "said passages progressively increase the pressure of the air flowing throughthem toward said openingsoas to cause the combustible mixture discharged intosaid drum'tobe under relatively high pressure, said partition adjacent'the wall of said shell having openings for discharge of part of said annular air stream'from said fan into the annularspace between said drum and shell for admixture with thecombustion products discharged into said space through theperforations of said drum, and adjustable damper means associated with the last mentioned openings of said partition for regulating the relative amounts of air discharged through such openings and the first mentioned opening of said partition for regulating the pressure in said drum.

7. The methodof burning-fuel oil to secure substantially its complete combustion without formation of carbon' monoxide, utilizinga combustion chamber consisting of a drum of thin heatrefractory metal exteriorly definedby lateral and end walls, at least one of which walls," excluding one of said endwalls, is formed with perforations not exceeding approximately 0.018 square inch'intransverse cross-section and distributed in spaced relation in suchnumber as to present approximately from 0.05'to 0.14 square inch of total transverse cross-section per 'squareinch of perforated surface, with the total area of such surface in square inches being arithmetically approximately from 15 to 35 percent of the arithmetical value'of the cubic contents of the drum expressed in cubic inches, which method comprises discharging the fuel oil into said drum'at said excluded end wall thereof toward its opposite end in atomized state mixed with combustion air at the rate of approximately one gallon of such oil per hour for each 550 to 1600 cubic inches of the cubic contents of thedrum and burning within the drum the mixture in the form of a flame that is of such pattern that it is in such proximity to at least the perforated wall portion or portions so as to beat them to incandescence but in out-of-contacting relation to such portion or portions so as to be separated from them by gaseous combustion products, the amount of combustion air mixed with said atomized fuel oil so discharged into the drum being suflicient to maintain in the drum a pressure of approximately from 0.025 to0.2 inch of water above normal atmospheric pressure varying approximately directly and linearly with the amount of fuel oil so discharged into the drum, such air being substantially the only air admitted to said drum; and discharging the combustion products from said drum substantially solely through said perforations.

8. The method according to claim 7 in which the perforations are confined to the lateral wall of the drum.

9. The method according to claim 7 in which the perforations are confined to that end wall of the drum which is opposite its end wall at which the mixture is discharged thereinto.

10. The method according to claim 7 in which the perforations are in both the lateral wall of the drum and that end wall of the drum which is opposite its end wall at which the mixture is discharged thereinto.

11. A heater having, in combination, a drum combustion chamber having end and lateral walls, at least one of said walls, excluding one of said end walls, being formed with a multitude of relatively closely spaced small perforations for discharge of gaseous combustion products from said chamber, .a casing having a portion surrounding said lateral wall in spaced relation thereto, a combustion air blast tube of lesser transverse crosssectional area than that of saidchamber opening at one of itsends into said chamber adjacent the axial line of the latter through said excluded end Wall and opening at its opposite end into said casing in spaced relation to that end wall, a fluid fuel nozzle associated with said blast tube for discharging fuel into said chamber; means for supplying combustion air to said blast tube through its said opposite end for admixture with such fuel so discharged, and air to .the space within said casing about said lateral wall for flow therethrough in contact with said lateral wall and for admixture with the products of combustion discharged through said perforations, which means comprises a blower for directing an operatively annular blast of air surrounding the axial line of said blast tube toward the said opposite end to said tube, means including bafiies between said blower and the said opposite end .of saidtube in the path of said annular air blast for directing part of said blast inwardly toward said axial line, which last mentioned means forms passages for conducting such air so directed that extend toward said axial line and are of progressively decreasing. transverse cross-sectional area as they so extend for compressing such part and causing it to be projected at'high velocity into said blast tube through its said opposite end, the last mentioned means having provision for causing another part of saidannular air blast to be directed toward and into the space surrounding said lateral wall.

12. A heater according to claim 11 having adjustable damper means, associated with the means which includes the batfles, for regulating the amounts of air constituting the part of the annular air blast directed inwardly toward the axial line of the'blast tube and the part of said blast directed toward the space surrounding the lateral wall of the combustion chamber, whereby to regulate the pressure within said chamber.

References Cited in the file of this patent UNITED STATES PATENTS Garrett Dec. 24, 1940 Homing -2 May 15, 1951 .Sherman Sept. 8, 1953 Sherman Feb. 11, 1954

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