US2535923A

US2535923A - Vaporizing oil burner

Info

Publication number: US2535923A
Application number: US2623A
Authority: US
Inventors: Vaughn H Hill
Original assignee: Motor Wheel Corp
Current assignee: Motor Wheel Corp
Priority date: 1948-01-16
Filing date: 1948-01-16
Publication date: 1950-12-26
Anticipated expiration: 1967-12-26

Description

Dec. 26, 1950 v. H. HlLL 2,535,923

VAPORIZING OIL BURNER Filed Jan. 16, 1948 3 Sheets-Sheet 1 Mvsmoa BY VaughnH. H/'// ATTORNEYS Dec. 26, 1950 v. H. HILL 2,535,923

VAPORIZING OIL BURNER Filed Jan. 16, 1948 5 Sheets-Sheet 2 IN V EN TOR. Vuuyhn/f. H/Y/ ATTORNEY-5 Dec..26, 1950 v. H. HILL 2,535,923

VAPORIZING OIL BURNER Filed Jan. 16, 1948 3 Sheets-Sheet 3 n o a a A o I, n u n n n n n 2 0 u u --5 o 0 o o c o o o 0 o 0 o "-6 o o o o o o o o o o o D f -33 I2 0 o o o o o o o o o o o o E O O 0 O 0 v0 O O c F IN V EN TOR.

ATTORNEYS vary widely in their chemical structure.

Patented Dec. 26, 1950 VAPORIZING OIL BURNER Vaughn H. Hill, Lansing, Mich., assignor to Motor Wheel Corporation, Lansing, Mich., a

corporation of Michigan Application January 16, 1948, Serial No. 2,623

24 Claims.

This invention relates to a vaporizing type oil burner.

vaporizing oil burners are old and well known in the art, see, for example, the Valjean patent 2,073,270 and the Miller et a1. Patent 2,374,693.

It is an object of this invention to improve upon this general type of vaporizing oil burner so that it will burn cleanly, that is, without smoking, at all stages of operation of the burner and particularly at the low fire and pilot fire stages of operation of the burner.

This invention also contemplates a vaporizing oil burner which will burn cleanly and efficiently with any type of fuel oil on the market today, such, e. g., straight run distillate fuel oils, catalytically cracked distillate fuel oils.

The fuel oils that are on the market today T e mechanism of combustion of fuel oils is not known and many theories have been advanced on the mechanism of combustion, but it is known that some fuel oils are much more diflicult to burn efficiently in a vaporizing oil burner than others and are more prone to produce excessive carbon and soot deposits. These carbon and soot deposits are indicative of inefiicient or incomplete burning and they often foul up and stop the operation of the burner.

This invention contemplates a vaporizing type oil burner which will burn all types of fuel oil cleanly and emciently not only at high fire but also at low or intermediate and pilot fires.

These objects are accomplished by a vaporizing oil burner which has the following characteristics: (l) The burner will operate on natural draft or with mechanical or forced draft. (2) The oil inlet is conveniently located at the side of the vaporizing chamber. (3) The vaporizing chamber is shielded from the direct rays or radiation of the flame. (4) The vaporizing chamber is shallow and extends completely (360) around the burner. (5) The primary air is admitted close to the oil being vaporized so that it will form the air-oil vapor mixture substantially the instant the oil is vaporized and at as low a temperature as possible. (6) Bafiles are provided in the vaporization zone to prevent circumferential movement of the air-oil vapor mixture.

In the drawings:

Fig. l is a vertical section along the line 1-4 of Fig. 2 through the burner which is the subject of this invention.

Fig. 1A is a detail showing the relation of the lower row of primaryair holes and vaporizing chamber.

Fig. 6 is a section along the line 6-6 of Fig. 5 portion Fig. 7 is a vertical section of the lower of a third modified form of oil burner.

Fig. 8 is a section along the line 8-8 of Fig. 7.

.Fig. 9 is a vertical section through a. fourth modified form of vaporizing oil burner.

Fig. 10 is a bottom plan view of the burner shown in Fig. 9.

Fig. 11 is a top plan view showing one-half of; V

the burner shown in Fig. 9.

Referring more particularly to the drawings,

the side wall of the burner is designated I2 and the skirt of the combustion chamber in which the burner l2 ismounted is designated l3.

The upper portion of the burner is identical with the upper portion of the burner shown in the Miller et a1. Patent 2,374,693 and comprises in general a top wall l4 having an outlet ii, an anti-explosion bafiie 16 with a horizontal ring of secondary air inlet holes ll between baflie l6 and the lower edge of top 14 and another horizontal row of secondary air holes I 8 having their axes inclined upwardly and inwardly of the burner side wall. horizontal.

The improvement in the burner here under consideration is in. the lower or vaporizing portion of the burner which comprises a bottom portion having a flat circular or disk-like cen- The axes of openings I! are terportion l9 surrounded by a circular ring portion 20 which tapers inwardly and downwardly toward the center of the bottom and a bottom side wall 2| which is telescoped over the lower: edge portion of the burner side wall as at 22. If

desired, the overlapping portions 22 of the burn er bottom and side wall can be welded together.

An annular, bailie 23, which takes the form of a.

frustum of a cone, is supported above the center portion 19 of the bottom by a plurality of vertical bafiies 24 which are positioned in vertical planes radially of the center 26 of the bottom a of the burner and spaced circumferentially,

around (360) the burner bottom. .Bafiles 24 are spaced one fromthe other and extend bew tween conical bafile 23 and the side wall l2 of the burner. Bafiles 24 preferably are spaced symmetrically with respect to oil inlet 29. Each baiiie 24 is provided with a triangular slot 2'! in which the bafiles 24 interengage and support the conical baffle 23 above the center I9 of the bottom. An annular ring 28 is fixed to the bottom of the burner entirely around the circumference of the bottom center 89 in oil-tight relation therewith and serves as a wall to prevent the oil from flowing from the vaporizing portion of the burner on to the center portion l9 of the burner bottom.

The oil inlet is designated 29 and the bottom wall portion is is provided witha depression 30 adjacent the inlet 29 which serves as a sump in which a small body of oil collects,.particularly I at pilot flame.

A generally horizontal baffle 3| having a central opening 32 is positioned upon the upper edges of bafiles 2G and divides the burner into an upper chamber 33 and a lower chamber 34. Baffle 3E is slightly conical.

The side wall 12 of the burner is provided with seven horizontal vertically spaced rows of air inlet holes 35. The upper edge 38 of the conical bafile 23 is positioned just below the second from the bottom row of holes 35. The bottom row I (Fig. 1) of air inlet holes 38 is formed in the lower wall of an annular bead 31 and thus have their axes directed downwardly and inwardly (Fig. 1A) so that the jets of air flowing through the lowermost row of holes will be directed downwardly toward the bottom 28 between annular wall 23 and side wall 2! of the bottom. Thus, the; air flowing through the lowermost row of holes 33 will be directed to the surface of the liquid oil in the vaporizing chamber. The inwardly inclined bottom ring portion 20 forms a circular sump about which the oil from inlet 29 flows around to form a ring of oil, particularly at high fire. At low fire, and particularly at pilot re, the oil will not flow from inlet 29 360 about sump 20,

For purposes of description and not by way of limitation, the following may be set forth with respect to the number and size of air holes in l4 inches and an overall height of about 10 inches: In all forms of the burner shown in this application there is one row A of twenty-six secondary air holes it each having a diameter of .144 inch and one row'Bv of fifty secondary air holes ii -each having a. diameter of .1285 inch, and five horizontal rows of primary air holes: twenty-six air holes 35 in the top row 0 of primary air holes each having a diameter of .098 inch and twenty-six air holes in the second, third, fourth and fifth from the top rows (D, E, F, G) of primary air holes each hole having a diameter of .089 inch. In the burner shown in Fig. 1, the lower two rows H, I of air holes each contain twenty-six holes 33 each having a diameter of .086 inch.

InJthe operation of the burner the oil flows from inlet 29 upon and around the inclined bottom wall portion 26 and is vaporized adjacent the floor 20. In normal operation theoil level never reaches the top of ring 28. When the burner is burning at high fire flame will occur above outlet 15 in the top it of the burner and at low or intermediate fire the flame will occur principally in compartment 33 and at or above opening 32. Thus,- at low and high fire baths 4 3i and 23 cooperate to shield the oil in sump 26! from the direct heat rays of the flame. Thus, the oil in sump it is vaporized at a temperature much lower than the temperature of the heat rays from the burner flame. The air from the lowest row of inlet openings 38 is directed downwardly upon the oil in sump 2t and this air intel-mixes with the oil vapor the instant the vapor is formed and the air flowing on to the oil from the lowest row of air inlet openings keeps the oil at substantially the lowest temperature at which it will vaporize. It is highly important in the operation of a burner which will operate universally with any. type of fuel oil that the oil should be vaporized'at the lowest possible temperature and intermix with air the instant that it is vaporized. This mode of operation is highly important from the standpoint of eflicient operation of the burner to avoid soot and carbon deposits regardless of whether the burner is burning at pilot fire or high fire or at an intermediate stage. The vertical bafiles 2e are positioned in the vaporizing zone of the burner and prevent any circumferential movement of the air-oil mixture which movement is highly undesirable, particularly at intermediate and pilot fires.

Since heat/rays travel in a straight line, it should be noted that no straight line passing through baflie opening 32 can reach the liquid oil upon bottom 20 because every such straight line is intercepted by conical baffle 23. Thus, the

oil to be vaporized in sump 29 cannot be subjected to direct radiation from the flame at any stage of operation excepting the pilot flame. The pilot flame usually hovers fairly close to oil inlet 29.

The burner shown in Fig. 4 is identical with that shown in Fig. 1 except that the circurn ferential portion as of the burner bottom be tween wall '25 and the outer wall iii of the burner is inclinedupwardly from the outside of the burner toward the center of the burner.

The modified form of burner shown in Fig. 5 differs from the form shown in l only in the structure of the sidewall vof the burner bottom. The side wall of-theburner bottom'is designated 4| (Fig. 5) and is provided-with ancutwardly turned:circumferential flange The side wall 12 of the burner is provided at its lower edge with a circumferential flange which rests upon, and is welded to, flange An annular ring 5'5 of arcuate cross-section is welded along itslower and upper edges-to the inside face of side wall 4|. A horizontal row of non-nietering air inlet openings or slots 85 is positioned in the side wall M adjacent the top of ring 5. 3 and they discharge air into the annular chamber is formed by ring M and sidewall 41. There are twenty-six. slots '15 each one-sixteenth inch by one-quarter inch. Another horizontal row of holes 6? -s' located the lower inclined wall of ring openings ll are inclined downwardly and in wardly so that the air streams flowing through inlets (17 are directed upon the surface of the oil resting upon'incli'n'ed wall These openings t? are adjacent, or in close proximity to, the sur- The axes of The form of burner shown in Fig. 7 is identical with that shown in Fig. 4 except that the side wall 50 of the burner bottom is telescoped over the lower end of the burner side wall 2' and is welded or otherwise secured thereto as at 5|. The side wall 55 has an offset portion 52 forming a circumferential space 53 with the lower portion of the burner side wall [2. There are five horizontal rows of air inlet openings 35 each containing twenty-six holes as above described and one lower horizontal row. of air inlet holes 55 containing twenty-six holes each having a diameter of .113 inch. I Thus, in this form of the burner there are a total number of six horizontal rows of primary air inlet holes. It should be noted that the lower row of holes 55 is positioned close to the inclined bottom portion 43- and thus will admit air into the vaporizing chamber in close proximity to the surface of the oil so that this air will intermix with the oil vapor as soon as formed. Holes 55 have their axes horizontal rather than tilted as in the burners above described.

Fig. 9 shows another modified burner bottom construction. The upper portion of the burner is identical with that shown in Fig, 1. Bafile or partition 60 which divides the burner into upper and lower compartments 33 and 3 1, respectively, is the same as that shown in the Miller et a1. Patent 2,334,117. The burner bottom is preferably a single metal stamping consisting of an outer side wall 5!, a vapprizing channel wall 52 inclined downwardly and outwardly from the center of the bottom, an inner channel wall 53 and a conical top wall 64. ing an opening fifi at its apex is welded around its circumference to bottom wall 52 as at 67. Top wall 64 of the burner bottom is provided with a circumferential flange in the form of an annular ring 68 welded to the top 6d as at '52 and overhanging the vaporizing channel formed by walls 6|, 62 and 63. A horizontal row of air inlet openlugs 69 having horizontal axes are located in vertical wall 63. As in the form of burner shown in Fig. 1, there are five horizontal rows of air inlet openings 35 in the side wall l2 of the burner beneath top I aeach consisting of twenty-six holes and one additional lowermost horizontal row of holes 69 having twenty-six openings therein, each hole 69 having a diameter of .113 inch. Thus, this burner also has six horizontal rows of primary air holes. Air is supplied to holes 39 through opening 66 and the air jets or streams flowing from holes 69, which are positioned adjacent the bottom 62 of the vaporizing chamber, direct the air into the oil vapor as soon as it is formed. The air entering through opening 56 flows in contact with the wall fi l and thus is foreheated before passing through the holes 53 and this preheating of the air improves the operation of the burner.

In all forms of the burner the oil is supplied to inlet opening 29 through a conventional fuel oil control H which both meters the fuel and maintains the fuel oil at a constant level.

In a vaporizing oil burner safety requires that the bottom row of primary airholes be located in such position that the oil level in the burner un- A conical ring 35 hav vaporizing chamber.

6. the burner may be controlled or regulated. In the burners shown in Figs. 1 and 4, the lowest row of primary air openings 35 is substantially above this safety level and the air flowing through these holes is directed downwardly upon the oil in the vaporizing chamber.

In the form shown in Fig. 5, openings ll are below the required safety level but should the oil level in the burner rise above openings 47 it cannot escape from the burner bottom until it reaches the level of openings '15 which are above the required safety level. a

In the form shown in Fig. 7, openings 55 are below the required safety level but due to offset wall 52 this oil cannot escape from the burner until it reaches the upper edge of wall 52 which is positioned above the safety level.

In Fig. 9 if the oil level reaches holes 69, this oil cannot escape from the burner until it reaches the level of opening 66 which is above the required safety level.

In the burner shown in Fig. 9 the oil flowing into the annular vaporizing channel 61,-62, 63

from fuel supply opening 29 is protectedfromdirect radiation of the flame at low and high fires by baflle 68 which intercepts any rays passing through the Opening '13 in bafile 63. Further, the primary air entering the burners 69 is mixed with the oil vapor as soon as it forms in the vaporizing chamber or channel ring ii I, 52, 63.

In all forms of the burner the inclination of the lowermost walls of the vaporizing chamber; namely, walls 20, ii and 62, causes the oil from inlet 29 to form a ring completely around the 1, 63, 6|, Fig. 9) tends to cause the oil from,

inlet 29 to form a ring about the burner bottom and a ring of oil is formed even at intermediate fires when the rate of flow is less than at high fire. For example, ifthe oil is fed into the burner at a low rate, such as occurs at low fire, the oil will tend to form a narrow and shallow ring in the lowermost portion ill of the 5 burner bottom which is the line of junction of the lowermost edge of the inclined bottom wall 23 or 40 with the adjacent vertical side wall of the As the rate of feed of oil increases, the ring of oil will increase in depth and width and rise up along the inclined bottom wall of the vaporizing chamber. Thus, the inclining of the lower wall of the vaporizing chamber causes the oil from inlet 29 to form a ring and spread out around the circumference of the burner bottom rather than form a pool or pond close to inlet 29 as in the burners of the prior art and this feature also contributes to the burners ability to efficiently burn all types of fuel oil sold on the market today for vaporizing oil burners.

The vertical baffles 24 cooperate to form small mixing chambers in which the oil vapor is thoroughly mixed with air flowing through the lower row or rows of holes before the vapor can circulate and be subjected to direct heat radiation from the burner flame.

In the operation of the burner, such as shown in Fig. 1, the baflle 23 cooperates with the side wall 2| and the bottom wall 28 of the burner to form av circular vaporizing chamber for the liquid fuel and the oil vapor in this chamber Will mix with the primary air flowing into the vaporizing chamber through the lower row of air inlet openings. In normal operation the oil level will not reach the upper edge of annular ring 23. Hence, the mixture of oil vapor and air which occurs in the vaporizing chamber will be an oilrich mixture and particularly at the surface of the oil.

In the form of burner shown in Fig. 9, the vaporizing chamber will also take the form of an annular channel bounded by the side walls s! and t3 and the bottom wall 62. Here again the vapor and liquid fuel in the vaporizing chamber will be protected against direct radiation from the burner flame by baffie (it.

I claim:

1. Combustion apparatus of the vaporizing type comprising an open topped burner pot having a peripheral channel in the lower part of said burner pot, said channel having upright side walls and a bottom wall, a liquid fuel inlet for supplying fuel to said peripheral channel, a baffle 2. The combination claimed in claim 1 wherein the floor of said channel is inclined radially from the horizontal.

3. The combination claimed in claim 2 wherein the baffle takes the form of a conical ring.

4. Combustion apparatus of the vaporizing type comprising an open topped burner pot having a peripheral channel in the lower part of said burner pot, said channel having upright side walls and a bottom wall, a liquid fuel inlet for supply ing fuel to said peripheral channel, a baiile above said peripheral channel which shields the liquid fuelin said channel against direct radiation from the burner flame in all stages of operation above pilot flame, the side wall of .saidburner pot having a plurality of horizontal rows of spaced air inlet holes and an inwardly extending annular bead, each row of spaced holes extending completely around the periphery of the burner pot side wall and the lower wall of said annular bead having one of the lower rows of air inlet holes with the axes of the holes inclined downwardly so as to direct the streams of air flowing through said holes downwardly into the fuel vapor in said channel.

5. Combustion apparatus of the vaporizing type comprising a burner pct, name means positioned within the burner pot and substantially removed from both the top and bottom of the burner pot to form upper and lower compartments, baflle means being constructed and arranged to provide a substantially central opening affording communication between said compartments, the side wall of the burner but having a plurality of spaced primary air inlet openings arranged above and below the said bafile means, .a peripheral fuel channel in the lower part-of said burner pot below said bafiie means, said peripheral fuel channel being formed in part by the burner pot and extending around the lower part of said burnerpot, said channel having upright side walls 2'5 and, the side wall of the burner whereby the and a bottom wall, fuel supply means for delivering liquid fuel to said channel, and a baffle spaced from the sidewall of said burner pot and posi tioned in said lower compartment and beneath said aforesaid baffle means, the said .baflle intersecting any straight line drawn between the opening in said baflle means and the bottom of, said peripheral fuel channel.

6.. The combination as claimed in claim 5 wherein the bottom wall of said fuel channel is inclined inwardly from the periphery of the bottom of said burner pot whereby th liquid fuel flowing into .said channel tends to flow completely around the periphery of the lower part, of the said burner.

7. The combination as claimed in claim 61 wherein the said baffle .is positioned above and spaced from the bottom of said burner.

8. The combination as claimed in claim 7; wherein the bottom of the fuel channel is 'in-the form of a truncated cone and the battle is a, ring in the form of a truncated cone which flares outwardly and upwardly toward the first men-- tioned baflle means.

9. Combustion apparatus comprising a burner pot, a centrally apertured partition extending across the burner pot at a position substantially removed from both the top .and the bottom of the;

burner pot to form upper and lower communicating compartments within the burner pot, the

side wall of the burner pot having a pluralityzof;

spaced primary air inlet openings above and be low said partition, an open topped fuel channel formed in part by the burner pot and extending peripherally around the bottom of said burner pot and having a fuel inlet opening therein, said peripheral fuel channel having an upwardly extending inner side wall constructed and arranged to intersect any straight line between the bottom of said fuel channel and the central aperture in said partition whereby the liquid fuel insaid fuel channel is protected from direct radiation from any flame occurring at or above said aperture in the partition, some of the primary air inletopenings in the side wall of said burner pot be: ing located below the upper edge of the inner wall of said-fuel channel.

10. Combustion apparatus comprising a burner,

pot, a centrally apertured partition extending across the burner pot at a position substantially removed from .both the top and the bottom of the burner pot to form upper and lower communicating compartments within the burner pot,

the side wall of the burner pot having a plurality of spaced primary air inlet openings above and below said partition, the bottom of said burner pot having a peripheral valley, means for delivering liquid fuel to said valley preparatory to vaporizing and mixing of the same with air delivered through said air inlet openings, and a baffie positioned between the aperture in :said par-l tition and said valley .for protecting the liquid fuel in said valley against direct radiation from the flame of the burner occurringat or above said central aperture.

11. The combination .claimed in claim 10 wherein some of the primary air inlet openings are positioned adjacent said valley .so that theliquid fuel vapor intermixes with .air substantially as soon as it is formed.

12. The combination claimed in claim 11 in. cluding a plurality of vertical *baflles positioned in spaced relation about said valley beneath :said partition and between the aforementioned .baflle 14. In a vaporizing liquid fuel burner com prising an open top burner pot having a bottom wall and a side wall having a plurality of air inlet openings, aliquid fuel inlet near the bottom wall of said burner, a valley positioned adjacent to, and around the periphery of, the bottom wall, the bottom wall of said valley bein inclined inwardly from the periphery, some of the air inlet openings being positioned adjacent the said valley whereby air is supplied to the fuel vapor substantially at the surface of the liquid fuel in said valley.

15. The combination as claimed in claim 14 including a baffle positioned within the burner pot adjacent the bottom of said burner pot and extending completely around the inner periphcry of said valley for shieldin the liquid fuel in said valley against direct radiation from the flame of said burner.

16. The combination as claimed in claim 15 including a centrally apertured generally hori zontal partition extending across the burner above said bafiie and dividing the burner into upper and lower communicating compartments, the said baffle shielding the liquid fuel in said valley from direct radiation from any flame occurring adjacent or above said aperture in the partition.

17. The combination as claimed in claim 16 including a plurality of vertical baffles beneath said partition and between the aforementioned baffle and the side wall of the burner for dividing the lower portion of the burner into a plurality of vaporizing compartments.

18. Combustion apparatus of the vaporizing type comprising an open topped burner pot havin a peripheral channel in the lower part of said burner pot, said channel having upright side walls and a bottom wall, a liquid fuel inlet for supplying fuel to said peripheral channel, a bafiie in the form of a continuous ring positioned above said peripheral channel which shields the liquid fuel in said channel against direct radiation from the burner flame in all stages of operation above pilot flame, the side Wall of said burner pot having spaced air inlet holes including a plurality of holes in the lower part of the side wall for supplying air to the fuel vapor substantially as soon as the liquid fuel in said channel vaporizes, and a plurality of vertical baffles spaced peripherally around said channel between the aforesaid baflie and the side wall of the burner pot for dividing the lower portion of the burner into a plurality of compartments, said vertical bafiies having a clearance with the floor of said channel so that the liquid. fuel is free to flow along said channel.

19. Combustion apparatus comprising a burner pot comprising a bottom and a side wall, a centrally apertured partition extending across the burner pot at a position substantially removed from both the top and the bottom of the burner to form upper and lower communicating compartments within the burner, the side Wall of the burner pot havin a plurality of spaced primary air inlet openings above and below said partition. an open topped fuel channel formed in part by the burner pot and extending peripherally around the bottom of said burner pot and having a fuel inlet opening therein, an upwardly of said fuel channel and the central aperture in said partion whereby the liquid fuel in said fuel channel is protected from direct radiation from any flame occurring at or above said aperture in the partition, some of the primary air inlet openings in the side wall of said burner pot being located below the upper edge of the inner wall of said fuel channel, and a plurality of vertical baiiies positioned in said lower compartment and between the side wall of the burner pot and said baffle and spaced one from the other whereby the portion of the lower compartment between said baffle and the side wall of the burner pot is divided into a plurality of compartments.

20. Combustion apparatus of the vaporizing type comprising an open topped burner pot having a peripheral channel in the lower part of said burner pot, said channel having upright side walls and a bottom Wall, a liquid fuel inlet for supplying fuel to said peripheral channel, a bafiie for closing the opening defined by the inside wall of said channel and having an overhanging portion which shields the liquid fuel in said channel against direct radiation from the burner flame at intermediate and high fire, spaced air inlet holes in the side wall of said burner pot, a bottom wall for closing the opening defined by the lower edge of the inside wall of said channel and spaced from the above said baffle, an opening in said lower wall, and a plurality of openings in the inside wall of said channel for supplying air to the fuel vapor immediately as the liquid fuel in said channel vaporizes, said air being supplied to said last mentioned openings through the opening in said lower wall whereby the air in passing along the underside of said bafiie is preheated before passing through the openings in said channel wall for mixing with the fuel vapors.

21. Combustion apparatus of the vaporizing type comprising an open topped burner pot having a peripheral channel in the lower part of said burner pot, said channel having upright side walls and a bottom wall, a fuel inlet for said channel, means for supplying fuel in regulatable quantities through said fuel inlet to said peripheral channel, a baffle above said peripheral channel which shields the liquid fuel in said channel against direct radiation from the burner flame in all stages of operation above pilot flame, the side wall of said burner pot having spaced air inlet holes and a side wall of said channel having a plurality of holes for supplying air to the fuel vapor immediately as the liquid fuel in said channel vaporizes.

22. The combination claimed in claim 21 wherein the floor of said channel is inclined inwardly from the horizontal.

23. The combination claimed in claim 22 wherein the baffle takes the form of a conical ring.

24. Combustion apparatus of the vaporizing type comprising an open topped burner pot having a peripheral channel in the lower part of said burner, a fuel inlet for said peripheral channel, means for supplying fuel in regulatable quantities through said fuel inlet to said periph- 'burner flame in all stages of operation above UNITED STA'L'ES PATENTS 'pilot flame, and spaced air inlet holes in the Number Name Date -s1de Wall pf seed kmrn er pet including a plurahts 623,012 Grimm Apr. 11 1899 of holes 111 the mwez pan; of the slde wall fOl 2225 467 Breese Dec 17 .1940 supplying air to the fuel vapor immediately as 5 1 v 2,263,737 Mlller et a1. Nov. 25, 1941 the hquld fuel m saxd channel vaponzes. 302 287 Y I VAUGHN H HILL Behrendt ei; a]. Nov. 17, 1942 2,361,912 Breese Nov. '7, 1944 REFERENCES CITED 2,3 1, 67 Hager D60. 25, 1945 2,409,677 Grotenhouse Oct. 22, 1946 The followmg references are of record 1n the 10 V file of this patent: