US2208851A - Liquid fuel burner - Google Patents

Description

July 23,1940. J. H. MclLVAlNE Er AL LIQUID FUEL BURNER Filed Sept.v 23, 1937 2 Sheets-Sheet 1 July 23, 1940. J. H. MclLvAlNE `r-:T AL 2,208,851

LIQUID FUEL BURNER Filed Sept. 23. 1937 2 Sheets-Sheet 2 Patented July 23, 1940 .i

Unirse sTArss PATENT OFFICE delphia, Pa.,

Illinois assignors to Mcllvaine Burner Corporation, Chicago,

Ill., a corporation of Application September 23, 1937, Serial No. 165,262

12 Claims.

` bustion head.

In our application Serial No. 74,952, led April 17, 1936, we disclosed a combustion head of builtup sectional construction consisting of a metallic overow pan or base, a metallic burner tray thereon, a metallic enclosing ring surrounding the tray and supported on the pan, and a top of refractory material supported `on the ring and having a central flame opening therein. It is the principal object of our present invention to 'mplify and improve said construction by combning the ring and top in one piece of refractoryA material, whereby to reduce the number of partsv from four to three, and to provide, as an integral part of the tray, the hood cooperating with the fuel vaporization groove therein, instead of having this hood provided as a part vof the enclosing ring, whereby to further simply the construction and insure correct alignment between the hood'4 and groove, important for good combustion.

Another object is to improvethe operation off the combustion head by providing an oil retaili-Vv ing wall near the front wall of the vaporizingn groove and reaching to the flame pockets at the? opposite ends of the groove where wicks arefpro-f vided behind'the retaining wall to absorb *oil and distribute the flame equally to the two pocketspg'' while at the same time making certain thatv lthe flame on a low setting ofthe burnerwill stay' close to the front wall and thereby prevent ex` tinguishment of the flame while also keeping the'v groove hotter. The wicks arealso of advantagel for quicker starting of the burner.

A further object with a view toimproved peri' ormance is to provide a vertical side wall 'onthe tray alongside the vaporizing groove to confine the flame and keep it from reaching off the edge of the tray and under it and damaging thefover-" flow pan therebeneath, and also providing for'. the admission of air from the airV conduit directly beneath the tray to flow across the bottom of the tray and up aroundthe back or far. sideV ci the tray and into the flame, so as to confine the heat to the tray itself so much as'possible while keeping the overflow panas coolas .posgsible, and at the same time supply ample-sec-L ondary air to the flame for good combustion.:ifI

The invention is hereinafter described'byaref-; erence to the accompanying drawings, in which-:g

Figure 1 is a fragmentary view partly in sideJ elevation and partly in central `vertical-.secti fn1.

(Ci. 15s-,491)

of a combustion head or fire-pot made in accordance with our invention;

Fig. 2 is a horizontal section approximately on the line 2-2 of Fig. 1;v

Fig. 3 is a vertical section on the broken line 3-3 of Fig. 2, and

Fig. 4 is a cross-section on the line 4-4 of Fig. 3, but showing most of the tray and enclosing ring in front elevation.

The same reference numerals are applied to corresponding parts throughout the views.

The present invention being concerned primarily with the combustion head or fire-pot, the rest of the oil burner has been omitted from the general view, Fig.' l. At any rate, the rest of the burner is disclosed in the copending application Vpreviously mentioned, and it will therefore suffice to state that the air tube or conduit 5 for delivering air to,the combustion head 6 has air supplied thereto under pressure by a centrifug-al fan in a blower housing communicating with the other end of the air conduit. The pipe 'l for delivering oil to the combustion head extends lengthwise inside the air conduit and communicates at its other end with a control valve arranged to be adjusted to regulate the oil feed according to the heat demand, the oil flowing gravity through the pipe 1 to the combustion head where it is vaporized and mixed with air and burned in the novel manner described in the copending application, and also briefly desc-ribed hereinafter.v The oil feed is regulated simultaneously with the adjustment of an air shutter on, the blower housing as described in Mcllvaine lPatent 1,797,293 sothat there will be the correct amount of air supplied to the com-` bustion head in proportion to the oil supplied, the oil and air being proportioned correctly as the control valve'is opened wider and wder'in each step in the progressive opening of the shutter plate, whereby to obtain good combustion in the low llame, which serves as a pilot, and'in the various intermediate sized flames and in the high flame. In the event the flame in the combustion head is accidentally extinguished, oil overflows the tray 8 into the Aoverflow pan 9 and runs out through an outlet l and is conducted through la' return pipe ll' to a trip bucket forming part of a trip mechanism, whereby the oil flow to the combustionhead is shutoff.

The combustion head B is made of three separate parts:

i (l) The overflow gral Vwith the end of the air conduit pan 9 cast preferably inte.

(2) The burner tray 8 supported in the pan 9, and

(3) The enclosing ring or cover I2 notched, as at I2', to fit over the end of the air conduit 5 and supported on the pan 9 and surrounding the tray 8.

The pan 9 and ring I2 together constitute a casing wherein the tray S is enclosed and into which air from the conduit 5 is adapted to be delivered for mixture with the vapors rising from the tray 8 so as to supply a ame projecting` from the casing. This built-up sectional construction is of advantage because it allows each part to expand and contract freely relative to the other parts, whereas a fire-pot cast in one piece would be apt to crack, due to uneven heating. In this way we can use ordinary cast iron for the metal parts, instead of special heat resisting metals, and thereby effect a saving in cost. Furthermore, the sectional construction makes fo-r simpler and less expensive individual castings and it permits making the cover I2, which is subjected to the most intense heat, of refractory or other heat resisting material. The sectional construction also enables replacement of any part in case it gets cracked or .burns out, and obviously such replacement means very little expense as compared to the necessity for replacing the entire combustion head, and, since the parts are loosely assembled on one another, it takes very little time to assemble and disassemble the head, there being no bolts or screws to loosen, which invariably become dil'lcult to loosen after they have been subjected to the heat of the furnace for any length of time.` In this connection, we would call attention to the fact that the most expensive part of the assembly, namely, the combined overflow pan .CJl and air conduit 5, is safeguarded against likelihood of cracking, due to heating, by the fact that the thick tray 8 shields the overow pan from the heat; otherwise the casting of the overflow pan integral with the air conduit would not be feasible. While the cover i2 is made in one piece of ceramic material, it will be noticed that a deep vertical groove I3 is provided therein extending continuously from the bottom of the side wall I4 on the inside up to the top wall I5 and alc-ng the bottom thereof and up through one side of the ame opening I5 and along the top wall and down the side wall again to the bottom, whereby to define a plane of fracture where the cover will be sure to crack when expanded by the heat of the flame. This fracture thereafter permits free expansion and contraction and avoids danger of the cover cracking elsewhere and possibly requiring re` placement, although before the cracking along this predetermined line, the cover is one continuous piece and will have the requisite strength for shipment and handling prior to its installation. In that way, this otherwise fragile part issafeguarded against breakage before installation.

The overflow pan 9 is downwardly offset in relation to the discharge end of the air conduit 5, so that the burner tray 8 which rests on the pan Sis supported in a plane with its top surface about level with the bottom of the air conduit. There is a rim Il on the pan 2 and an upwardly projecting bead I8 on the bottoml of the pan `inwardly spaced from the rim. The cover I2 is supported on the pan between the rim Il' and bead I8 on a plurality of downwardly projecting bosses or feet I9 molded integral with the cover. The cover is suitably cemented in place, as indicated at 28. The bead I8 forms the rim of a drain cavity 2| communicating with the outlet I0, as at 22, Fig. 4. The cavity 2I has the same general shape as the burner tray 8 which appears in plan View in Fig. 2. The tray has three feet 23 serving to support the same in elevated relation to the bottom of the pan S in the cavity 2E so that any oil overowing the tray will be free to flow across the bottom of the pan to the drain opening 22. This spaced relationship also permits air circulation under the tray for cooling purposes, as will presently appear. The fact that the tray has contact with` the pan only at three points, minimizes heat transfer from the tray to the pan. The tray has a hood 25 cast integral therewith extending lengthwise relative to the oil vaporizing` groove 25 in the tray and spaced vertically from the bottom of said groove to the extent best illustrated in Fig. 3. The straight front edge 25 of the hood 25 has abutment with the end of the air conduit 5 along the upper wall thereof, whereby to locate the tray 8 squarely in relation to theend of the air conduit but with the front wall 2l spaced from the end of the air conduit to define a vertical air inlet passage 28 for the delivery of air directly from the air conduit down and between the tray 8 and pan 9, as indicated by the arrows a, Fig. 3. This air flowing between the parts 8 and 9 keeps the pan 9 cool and it also is used as secondary air to support combustion in the head 6, it being condncted upwardly at the far side of the tray 8 from the conduit 5 between the tray and the cover I2, as indicated by the arrows b, Fig. 3. The fact that the hood 24 is integral with the tray 8 is of advantage because it insures accurate relationship between `the hood 24 and groove 25 and at the same time proper relationship between the hood 25 and air conduit 5, while locating the tray as a whole in the proper relationship to the air conduit. and providing for the air circulation just described.

As described in our copending application, the front wall 21 of the tray has a notch 29 therein to receive and locate the downwardly bent end of the oil pipe 'I so as to have the oil discharged into the groove 25 at about the middle. Now, obviously with the air entering the combustion head from the conduit 5 between the top of the wall 'I and the bottom of the hood 24, it follows that the incoming air` will be deflected downwardly by the curved portion 38 of the hood toward the groove 25, and since the wall 21 forms a transverse balile withv respect tothe air current, a whirling motion of some of the air on substantially horizontal axes will be set up in a clockwise direction, as indicated by the arrows c, Fig. 3. These may be termed eddy currents'. The groove 25 is somewhat wider than the discharge end of the air conduit, as indicated in Fig. 2, and there are, moreover, two obstructions or baies 3l and 32 on thegfront wall 27 on opposite sides of the oil pipe locating notch 29 so that the two ends of the groove 25 are shielded from the direct play of the air current thereon. This results in a whirling motion of air on vertical axes in the name pockets 33 and 34 defined behind these baiiles at opposite ends of the groove 25, the air whirling in a clockwise'direction in pocket .33, as indicated by the arrow d,.Fig. 2, andin a counterclockwise direction in the pocket 34, as indicated by the arrow e, Fig. 2; Now, since the top of the wall 2l is appreciablyfbelow the bottom ofthe curved portion-3010i the hood=24, it follows that some air .-ows. nearly/:straight through and into the combustion head fromthe air conduit 5 over the.

CTI

groove 25, as indicated by the large gently curved arrow ,f in Fig. 3. This air owing nearly straight through, carries with it the eddy currents c, d and e, as represented in Fig. 2, wherein it will be noticed how the clockwise and counter'clockwise currents d and e gradually reduce in radius as they get farther and farther down stream. In other words, these eddy currents d and e whirling on vertical axes come in contact with the eddy currents c whirling on horizontal axes and the horizontally flowing air current f, and are thereby gradually turned toward horizontal axes. This churning of the air at c, d and e, it should be remembered, occurs in the groove 25 into which oil is being delivered from the pipe 1. The tray 8 which, upon starting the burner, has been preheated by a gas torch, or in some other suitable manner, and which thereafter remains heated by the flames of the burning combustible mixture of oil vapors and air is hot enough at the groove 25 to vaporize the raw oil upon contact thereof with the groove. The cil .vapors in the groove are picked up bythe whirling air currents c, d and e in what may be termed pre-mixing; then these rich mixtures coming in contact with the main air current f, form a leaner mixture that will burn with a clean, hot flame. The flame is visible through the opening I6 on low, as two distinct tongues issuing from the vicinity of the pockets 33 and 34 onto the spirally formed bottom 35 of the tray 8. This indicates how great an effect these pockets have upon the operation of the Combustion head; Without these pockets there would be danger of the flame being blown out, but since these pockets are protected by the baffles 3| and 32, respectively, the flames originating therein will not be extinguished. The ballles 3l and 32 are closer together thanthe walls 36 and 31 defining the sides of the spiral bottom 35, thereby leaving the side portions of the spiral surface somewhat protected from the direct play of the air flowing up the middle of this surface. The two tongues referred to as being visible on low are seen as made up of numerous small whirling flames, indicating how the. eddy currents d and e originating in the pockets 33 and 34 are carried forward with the main air current f over the spiral bottom 35 of the tray. Of course, when the burner is turned up to a medium or a high flame, there are no longer two distinct tongues of flame as just described, but one large flame forms from these two flames, which, as it builds up, gradually reaches farther and farther over the spiral bottom 35 of the tray and finally issues from the combustion head through the opening I6 with a spinning motion, as indicated by the arrows g in Figs. 2 and 3. The cover l2 confines the air delivered to the combustion head and causes it to mix into the flame to support combustion, the secondary air b, previously referred to as flowing up around the sides of the.

tray 8 on the far side thereof remote from the air conduit 5, being delivered into the ame to support combustion and avoid carbon deposits. It is obvious that the tray 8 relies upon the cover l2 for its proper functioning. The flame on high is best described as an inverted cone, having a counterclockwise spinning motion. This direction-of spinning motion results from the way the air is delivered into the combusion head at one side of the cover I2, between the vertical walls 36 and 3l of the tray. The side wall 36 is substantially semi-circular surrounding the spiral surface 35. The latter has a gradual rise from the grooveY 25 through approximately 1809- and then, as indicated atl 38, has an abrupt rise to deflect the llame upwardly and out through the opening I6. 'I'he spinning motion given the flame accounts for its spreading out in the form of an inverted cone after it leaves the combustion head. The llame does not describe a true inverted cone, but rather an inverted cone of oval shape, due to the oblong shape of the opening I6. This tends to flatten out the vflame and give it greater width so as to make for better heat transfer to the side walls of the furnace. Y

It will now be noticed that the tray 8 has a series of steps 39-43 formed on the spiral bottom 35 resembling a spiral staircase. The first step 39 which is parallel with the groove 25 and with the first step 40 of the spiral steps, represents an appreciable rise from the level of the groove 25, but the spiral steps 40-43 which radiate from the center 44 of the tray have small risers. This formation is to prevent surging of oil when the burner -is suddenly turned from low to high. AUnder those conditions, the tray 8 is not heated to a high enough temperature because of the low flame and therefore does not have sufcient residual heat to vaporize the suddenly increased inflow of oil. If it were not foi` these steps 39-43, a deep pool of oil would form in the groove 25 and flood a large portion of the spiral bottom 35, and the air current impinging upon the edge of this pool would wash some oil up on to the hotter part of the tray and cause Vaporization there, with the result that the combustion head would burn with an uneven flame until the tray would reach a higher temperature, due to the radiant heat of the larger flame, and the level of the oil would subside to the edge of the groove 25, or some other point of stability. Then too, if the oil were allowed to run too far forward on the surface 35, the products of combustion passing over the surface of the oil would contaminate the vapo-rs rising therefrom and the flame would become hazy. With the present construction, when the burner is set for a low llame, the oil is vaporized in the groove 25 just as soon as it comes in contact with the hot surface thereof, and then when the burner is turned up for a higher llame the oil spreads over the bottom of the groove, which confines the oil as much as possible close to the air intake so as to produce an intimate mixture of air and vapor, but when the oil enters faster. than it is vaporized, upon sudden turn-up from low to high, oil will fill the groove and finally run out over the surface 45 to the step 39. The step 39 having an appreciable riser, connes the oil again as close as possibleto the air intake to continue producing an intimate mixture o-f air and vapors and avoid the` Acondition previously referred to of having products of combustion passing over the surface of the oil and contaminating the vapors. 'Ihe flame will ordinarily build up fast enough to stem the tide so that the oil will not pass the step 39 at its highest level, but, if the oil should rise above the step 39, it is confined by the step 40, and so on with regard to steps 4|, 42 and 43. In any event, it is apparent that whichever step is confining the -oil pool, there is a sharply defined boundary for the pool; the oil cannot surge forward and result in an uneven flame and the hazy condition previously described. As the tray heats up, the level of the oil subsides until finally the oil is vaporized mostly in the groove 25. y l

In case the flame is accidentally extinguished and-oil continues to 4ilow into thegroove 25, it 75?' will fill the tray and then run over the edgeinto the overflow pan 9 and findits way tothe tri-p, bucket previously mentioned,`so as to shut off the oil supply. y

An important novel featurey of the, present combustion head is the provision of the vertical side wall 46 alongside the pocket 33 cast integrally with the tray 3 and joined to the adjacent end of the hood 24. This wall prevents the flame from reaching out under the tray and coming into contact with the pan 9 therebeneath; the flame is compelled to remain onthe spiral surface 35. Still another important feature of the present combustion head is ,the provision ofthe projections ll'l and i8 on the inside of the cover l2 adjacent the grooved portion 25 of the tray 8 closing up the space that would otherwise be left between the wall L16 of the tray and the adjacent wall of the cover {2whereby to prevent secondary air from fiowing alongside the trayv and insure its flowing down through the passage 28. The projection d8 serves mostly as an extension of the wall fili to keep the flame from reaching off the tray down between the tray and the side wall of the cover I2 and coming in contact with the pan 9. Another projection @8 is formed on the opposite inside wall of the cover l2 to fit closely against the top edge of the tray for a similar purpose as the projection l'i. In that way, all of the secondary air is admitted through passage 28 and caused to flow in the direction of the arrows a, Fig. 3, under the tray from the air conduit 5 to the opposite side of the tray where it is delivered, as indicated at b, Fig. 3, into the flame by following upwardly around the tray 8 at that side thereof. In other words; with the present construction, the flame is properly confined to travel in a spiral path, asv above described, and is conned strictly to the top of the tray, and the secondary air is caused to travel under the tray for cooling it and the pan therebeneath and is thereafter delivered into the flame to support combustion.

Another important feature of novelty in the present construction is the oil retaining wall or rib Ell provided in the groove 25 near the front wall 21. This forms a small narrow raw fuel trough 5l alongside the wall 21 into which the oil from the pipe l is discharged. The trough localzes the oil in the region of the asbestos wicks 52 inserted in the ends of the trough. Very little vaporization takes place in this trough 5I. These wicks distribute the flame-equally tothe pockets 33 and 34, the wicks being of equal size. Furthermore, they tend to anchor the flame close to the wall 2l' softhat there is less danger of the flame on low being extinguished.v A further advantage of this arrangement, wherein all of the oil on low is retained in the raw fuel trough 5l and two small names reach out from wicks 52 over the bare bottom surface of groove 25, is that this bare surface heated by these flames is kept hotter than if it were covered more or less by a thin layer of oil, such as would be present there if the wall Eil were not provided to retain the oil in the trough 5l. Sudden turnup is therefore not nearly so apt to result in the flame being extinguished, because the rst oil overowing the wall 59 is promptly vaporized by contact with the hot bottom surface of groove 25 and the flame therefore builds up easily from low to highf We have also found that with these wicks the burner can be started more quickly than otherwise.

It is believed thel foregoing description conveys versely relative to and in the path of the air discharged from said conduit, means defining a flame pocket as an extension of one end of said groove out of the path of the air entering said casing, the fuel vaporization groove including a raw fuel trough next to and extending transversely relative to the discharge end of said air conduit, one end of said raw fuel trough reaching into the flame pocket, a fuel absorbing wick of incombustible material in said raw fuel trough at the flame pocket end thereof, an air deflector El" over said groove extending transversely relative to the discharge end of the conduit and arranged to direct air downwardly into said groove, and a baffle shielding said pocket from the incoming air.

2. In a liquid fuel burner, a casing having a top flame outlet opening, a substantially horiaantal air conduit communicating with the side oi said casing, means in the bottom of said casing providing. a liquid fuel vaporization depression below and in juxtaposition to the discharge end 5r" of the air conduit, means providing a raw liquid fuel trough in transverse relation to said air conduit and between the discharge end thereof and said fuel vaporization depression and arranged to have liquid fuel overflow the side thereof into said depression to be vaporized by Contact with the hot bottom of said depression so as to supply vapors to mix with the air from the conduit to form a combustible mixture, a fuel supply pipe communicating with said trough to deliver raw liquid fuel thereto, means providing a flame pocket enclosing the end of the trough and depression so as to be alongside and out of the path of the air entering said casing, said pocket being adapted in the operation of the burner to contain air whirling about a substantially vertical axis alongside the main current of air flowing into the casing substantially horizontally over the fuel vaporization depression, and a fuel absorbing wick of incombustible material in the flame pocket end of said trough.

3. In a liquid fuel burner, a casing having a flame outlet opening, an air conduit communicating with said casing, a burner tray in said casing having a fuel vaporization groove provided tlierein behind a front wall extending transversely relative to the discharge end of said air conduit, said wall rising to a predetermined elevation above a spiral surface on the tray extending from the other side of the groove, whereby air iiowing substantially horizontally over said wall and ovei1 said groove will entrain vapors rising from the groove and carry the burning mixture over said spiral surface, said fuel vaporization groove including a raw liquid fuel trough next to the front wall and having an oil retaining wall spaced from the front wall rising from the bottom of the groove to a predetermined elevation below the top of the front Wall, means for delivering raw liquid fuel to said trough, and a pair of fuel absorbing wicks of incombustible material in said trough adjacent opposite sides of the discharge end of the air conduit out of the direct path of air flow into said casing.

4. Ina liquid fuel burner, a casing having a llame outlet opening, an air conduit communicating with said casing, a burner tray in said casing having a fuel vaporization groove provided therein behind a front wall extendingtransversely relative to the discharge end of Vsaid air conduit, said wall rising to a predetermined .elevation above a spiral surface on the tray extending from the other side of the groove, whereby air flowing substantially horizontally over said walle and over said groove will entrain vapors rising from the groove and carry the burning mixture over said spiral surface, said fuel vaporization groove in'- cluding a raw liquid fuel trough next to the front wall and having an oil retaining wall spaced from the front wall rising from the bottom of the groove to a predetermined elevation below the top of the front wall, means for delivering raw liquid fuel to said trough, a pair of fuel absorbing wicks of incombustible material in said trough adjacent opposite sides of the discharge' end of the air conduit, yand a pair of vbaffles rising from charge end of said air conduit, said wall rising f to a predetermined elevation above a surface extending from the other side of the depression, whereby air flowing substantially horizontally over said wall and over said depression will entrain vapors rising from the depression and carry v the burning mixture over said surface, said fuel vaporization depression including a raw liquid fuel trough next to the wall, means for delivering raw liquid fuel to said trough, a pair of fuel absorbing wicks of incombustible material in said trough adjacent opposite sides of the discharge end of the air conduit, a pair of baffles rising from the top of said wall in laterally spaced relation on opposite sides of the discharge end of the air conduit and shielding the wicks from the incoming air, and an air deilector over said depression extending transversely relative to the discharge end of the air conduit and arranged to direct air downwardly into said depression.

6. In a liquid fuel burner, a casing having a flame outlet opening, an air conduit communicating with said casing, means in said casing providing a fuel vaporization depression behind a wall extending transversely relative to the discharge end of said air conduit, said wall rising to a predetermined elevation above a surface extending from the other side of the depression, whereby air flowing substantially horizontally over said wall and over said depression will entrain vapors rising from the depression and carry the burning mixture over said surface, said fuel vaporization depression including a raw liquid fuel trough next to the wall, means for delivering raw liquid fuel to said trough, a pair of fuel absorbing wicks of incombustible material in said trough adjacent opposite sides of the discharge end of the air conduit, and an air deflector over said depression extending transversely relative to the discharge end of the air conduit and arranged to direct air downwardly into said depression.

'7. In a liquid fuel burner, the combination of an overflow pan, an air conduit extending horizontally to one side thereof, a burner tray 0n which liquid fuel 'is adapted to be vaporized 1in the presence of air and burned,`said tray being supported on the overflow pan with an air space left'between the bottom of the tray and the pan, said tray having an' upright front wall adjacent the end of the air conduit reaching to a height above the'-'bottom thereof, means for delivering liquid fuel to said tray at a pointv next to said wall, an air deflecting hood on the tray reaching from 'the end ofthe air conduit at the top thereof over a portion of the tray adjacent said front wall and formed so as to deilectsome of the incoming air downwardly for mixture with fuel vapors in the tray, said hood serving by-engagement with the end of the air conduit to space the front wall of the tray-from the end of theair conduit so as to provide an air passage from the air conduit ,directly to the space under the tray at thatside of the tray adjacent the air conduit, andan enclosing cover for said tray resting 'on said overflow pan around the tray, the cover closely surrounding a fraction of thetray adjacent the end of the air conduit but being spaced annularly with relation tothe rest of the tray remote from the air conduit, said cover'having flame outletopening above the tray.

8. In a liquid fuel burner, a casing having a flame outlet opening, an air conduit communicating with said casing, means in said casing providing a fuel Lvaporization groove extending transversely'relative to and in the path of the'air'dis- .charged from said conduit, means defining a ame 'pocket as an extension of one end of said groove over said groove extending transversely relativeA to the discharge end of the conduit and arranged to direct air downwardly into said groove.

9. In a liquid fuel burner, lthe combination of an overflow pan, an air conduit extending horizontally to one side thereof, a burner tray on `the presence of air and burned, said tray being supported on the overflow pan with an air space left between the bottom of the tray and the pan, said tray having van upright front wall adjacent the end of the air conduit reaching to a height above the bottom thereof, means for delivering liquid fuel to said tray at a point next to said wall, an air deflecting hood reaching from the end of the air conduit over a portion of the tray adjacent said front wall and formed so as to deflect some of the incoming air downwardly for mixture with fuel vapors in the tray, means serving to space the front wall of the tray from the end of the air conduit so as to provide an air passage from the air `conduit directly yto the space under the tray at that side of the tray adjacent the air conduit, and an enclosing cover for said tray resting on said overflow pan around the tray, the cover closely surrounding a fraction enlarged to form a projecting right angular corner portion, said corner portion being grooved parallel to one side of said corner `portion to provide a longitudinally extending vertical outer wall rising to a certain elevation above a longitudinally extending vertical shoulder in spaced parallel relation thereto defining the other side of the groove, said tray being adapted to have air delivered thereto substantially horizontally over said outer wall toward the shoulder to entrain vapors rising from the bottom of the groove and carry the burning mixture over the remaining circular portion of said tray, said circular portion having a spiral top formation starting from the top of the aforesaid shoulder and gradually rising therefrom, said corner portion being further formed'to provide in the groove a partition wall in parallel spaced relation to the outer wall and rising to an elevation well below the elevation of the outer wallso as to form therebetween a shallow raw liquid fuel trough into which raw liquid fuel is adapted to be delivered from a liquid fuel supply pipe, and fuel absorbing wick means of incombustible material in at least one end of said trough.

1l. In a liquid fuel burner, a casing having a flame outlet opening, an air conduit communicating with said casing, means in said casing providing a fuel vaporization groove extending trans- Versely relative to and in the path of the air discharged from said conduit, means dening two flame pockets as extensions of both ends of said groove out of the path of the air entering said casing, the fuel vaporization groove. including a raw fuel trough next to and `transversely relative to the discharge end of said air conduit, the ends of said trough reaching into the ame pockets, fuel absorbing wicks of incombustible material in said trough at the flame pocket ends thereof, anair deflector over said groove extending transversely relativeA to the discharge end of the conduit and arranged to direct air downwardly into said groove, and bales shielding said flame pockets from the incoming air.

12. In a liquid fuel burner, a casing having a top flameoutlet opening, a substantially horizontal air conduit communicating with the side of said casing, means in the bottom of said casing providing a' liquid fuel vaporization depression below and in juxtaposition to the discharge end of the air conduit, means providing a raw liquid fuel trough in transverse relation to said air conduit and between the discharge end thereof and said fuel vaporization depression and arranged to have liquid fuel overflow the side thereof into said depression to be vaporized by Contact with the hot bottom of said depression 'so as to supply vapors to mix with the air from the conduit to for ma combustible mixture, a fuel supply pipe communicating with said trough to deliver raw liquid vfuel thereto, means providing two flame pockets enclosing the opposite ends of the trough l and depression so` as to vbe alongside and out of the path of air entering said casing, said pockets being adapted in the operation of the burner to contain air whirling about substantially vertical axles alongside the main current of air flowing JOHN H. MCILVAINE. PETER I. HOLLMAN.

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