US3017925A

US3017925A - Burner units and methods

Info

Publication number: US3017925A
Application number: US838818A
Authority: US
Inventors: Richard F Van Tubergen; Iii James L Breese; Milton D Huston
Original assignee: Controls Company of America
Current assignee: Controls Company of America
Priority date: 1959-08-28
Filing date: 1959-08-28
Publication date: 1962-01-23
Anticipated expiration: 1979-01-23
Also published as: FR1248222A

Description

Jan. 23, 1962 Filed Aug. 28, 1959 J. L. BREESE ETAL 7 Sheets-Sheet l F191 f mm |00 v 0 /0 u a o o o o 16a N 76d M nooo' oooooo o 0 ooooaooooooaonn SMSOODOOQSQOSGQ I GQOIQGQGQOOOO0 3 i ,-0 o o 24 `27a ol `\s fa Il 72 torre @ys Jan. 23, 1962 J. BREEsE ETAL 3,017,925

BURNER UNITS AND METHODS Filed Aug. 2s, 1959 v sheets-sheet 2 Jan. 23, 1962 J, BREESE ETAL 3,017,925

BURNER UNITS AND METHODS Filed Aug. 28, 1959 7 Sheets-Sheet 3 [53 l Ill 32 0'/ f 5/ l 52 75 f f 48 l 77 4f if t '32 f x F40 39 50 /I' i 'I :f 4/ llg.

f 33% v4 72W ff I6 i 72 i 73 L `-nu I 38 5 7/ l if, 7o H u /d/ 4 3 2 I wl Jan. 23, 1962 J. BREEsE ETAL BURNER UNITS AND METHODS '7 Sheets-Sheet 4 Filed Aug. 28, 1959 e n e Q Leo goeoseeo@ @@@QQQ MQMQZJ R wn lq Jan. 23, 1962 J. L. BREL-:SE ETAL 3,017,925

BURNER UNITS AND METHODS Filed Aug. 28, 1959 tsg/ Jan. 23, 1962 J. L. BRI-:ESE ETAL BURNER uNTs AND METHODS 7 Sheets-Sheet 6 Filed Aug. 28, 1959 2 2 w w |r v L1 1J a I i M JQ l i 1 l 1 1 l l l l l 1 IJ "t Z V|||\||\\J1||- 1/ l MA 7 0 l||| j l w /o M lll J 7N Jan- 23, 1962 J. BREEsE ETAL v3,017,925

BURNER UNITS AND` METHODS '7 Sheets-Sheet 7 Filed Aug. 28, 1959 United States Patent Oflce BURNER UNITS AND METHDS James L. Bresse, deceased, late of Santa Fe, N. Mex., by

Richard F'. VanTuhergen and .lames L. Brees@ III, executors, and Mil/ton D. Huston, all of Santa Fe, N. Mex., assignors to Controls Company of America,

Milwaukee, Wis., a corporation of Delaware Filed Aug. 28, 1959, Ser. No. 838,818

11 Claims. (Cl. 158-91) The present invention is directed to vaporizing pot type liquid fuel burners. One purpose of the invention is the provision of a vaporizing burner pot for liquid hydrocarbon fuels which operates with maximum efficiency.

Another purpose is the provision of an improved burner pot which is quieter and more stable in operation than conventional burner pots.

Another purpose is the provision of an improved burner pot which operates efficiently with catalytic ble-nds of hydrocarbon fuels and which lessens the tendency of these fuels to crack and produce large amounts of free carbon. i

Another purpose is the provision of an improved burner pot which operates over a large range of capacities without producing large amounts of free carbon.

Another purpose is to provide an improved method for burning liquid hydrocarbons in a pot type burner.

Another purpose is to provide an improved means of and method for heating a rich mixture of vaporized hydroearbon and air prior to the combustion of the iinal mixture.

Another purpose is to provide improved means for vaporizing the liquid hydrocarbon in a pot type burner without cracking.

Another purpose is to provide an improved pot bottom for pot type liquid hydrocarbon burners.

Another purpose is to provide improved air diffuser means for a pot type liquid hydrocarbon burner.

Another purpose is to provide improved baffling means for a pot type liquid hydrocarbon burner.

Another purpose is to provide improved ignition and air supply means for the initiation of combustion in a liquid fuel pot type burner.

Another purpose is to provide a burner producing a flame having a relatively small vertical extension as compared to llames of existing pot type burners of like size, whereby a heater or stove element of a substantially lower vertical clearance may be employe-d.

Another purpose is to provide an improved air diffuser for pot type burners.

Another purpose is Vto provide improved means for supplying secondary air to pot type burners.

Another purpose is to provide acomposite pot having a relatively small amount of heat resistant material employed only Where heat conditions make its use advantageous.

Other purposes will appear from time to time in the course of the ensuing specification and claims.

The present application is a continuation-in-part Aof application Serial No. 545,594, led on November 8, 1955, for Pot Type Burner with Spiralling Combustion and Central Air Tube, now abandoned.

The invention is illustrated more or less diagrammatically in the accompanying drawings wherein:

FIGURE l is an assembly view, in section, of the improved burner pot forming the present invention;

FIGURE 2 is a sectional view of the assembly shown in FIGURE l looking in the Adirection of the arrows 2-2 of FIGURE 1;

FIGURE 3 is a vertical axial section through a variant form of burner, with parts in elevation, the section being taken on the line 3--3` of FIGURE 4;

3,017,925y Patented Jan. 23 196,2.

FIGURE 4 is a partial plan view of the structure of FIGURE 3;

FIGURE 5 is a vertical axial section, on an enlarged scale, of the pot shown in FIGURE 3;

FIGURE 6 is a partial top plan View of the lower part of the structure of FIGURE 5;

FIGURE 7 is a section on the line 7-7 of FIGURE 6,;

FIGURE 8 is a side elevation of the structure of FIG? URE 6, with parts removed;

FIGURE 9 is a section on the line 9-9 of FIGURE 6;

FIGURE l0 is a vertical axial section, with parts in side elevation, of a variant form of burner;

FIGURE 1l is a partial vertical radial section of a vari ant pot detail;

FIGURE 12 is a diagrammatic illustration of the cornbustion taking place about the below described air diffuser structure;

FIGURE 13 is a partial radial vertical section of a variant form of pot;

FIGURE 14 is an axial section through an air diffuser structure as used in the pot of FIGURE 13; and

FIGURE 15 is a partial vertical axial section illustrating the variant formation of the.. pot side wall.

Likeelements are designated by like characters throughout the specification and drawings.

Referring generally now to the drawings, and in the first instance to FIGURE 1, there is illustrated a heater casing 1 within which is supported a burner pot 2. The burner pot 2 may rest, at its upper end, on a partition ring 3. The upper portion of the casing is subjected to a draft. Under some circumstances, a fan unit or other source of air pressure may be employed to force air into the interior of the casing. is fitted to the lower portion of the pot. It should be understood that suitable fuel control means (not shown) will be employed in conjunction with the fuel inlet 4 for delivering a liquid hydrocarbon fuel to the interior of the pot.

The side wall of the burner pot 2 is provided with several rows or levels of

air inlet apertures

5, 6, 7, 8, 9 and 10 which are adapted to admit primary and secondary air to the interior of the burner pot. The row of air inlet apertures 9 which is next below the uppermost row may be inwardly and upwardly directed as appears in FIGURE 1. The lowermost row of air inlet apertures 5 is preferably directed downwardly and more or less 4tangentially The lowermost row 5v is so directed that air delivered through these apertures is directed downwardly toward the bottom of the pot and is also directed on tangential lines with respect to the vertical axis of the pot. At high lire the

apertures

5, 6, 7 and 8 supply primary air, and 9 and 10 secondary air.

It should be noted that in FIGURE -1 the bottom of the pot 11 is illustrated as domed upwardly so that liquid fuel delivered through the inlet 4 initially flows around the outer edge of the pot bottom as at 12. In the embodiment shown the outer portion of the pot bottom is relatively flat, whereas the medial portion of the bottom is domed upwardly. In effect, a fuel receiving trough is provided which extends circumferentially around the pot and which is located adjacent the pot side wall. Thus fuel admitted to the trough is, to a substantial degree, heated by heat conducted downwardly by the pot side wall 2 when combustion is taking place at and above the top of the pot. The below described air diffuser structure also conducts heat to the trough.

According to the invention, an air diffusing tube assembly, designated generallyat 13, is supported in the center of the pot. This assembly includes an inner air supply tube 14 which is inserted in the pot bottom and is in communication with the air space beneath the bottom of the pot. The tube 14 makes a snug lit with a down- A fuel inlet pipe 4 wardly turned rim 14a which surrounds a central aperture in the upwardly domed portion of the pot. It may be welded to the rim 14a. A primary purpose of the air diffuser, as will later appear, is to heat the rich incombustible mixture which rises in the pot.

The assembly 13 includes an outer tube or air diffuser housing 15 which is spaced from the wall of the inner tube 14 to define an air chamber therebetween. The outer tube 15 may be supported in the position shown by being affixed to an upper partition member 16 which has a shoulder 15a resting on the upper edge of the tube 14 at a level adjacent the upper portion of the burner pot. The member 16 is provided with a plurality of apertures 16a to allow air to pass to the space between 14 and 15. The apertures 16a are proportioned to maintain the air within the diffuser housing 15 at a relatively low pressure. A lower member 17, in the form of a bafe, may be affixed to the lower portion of the tube 15. The member 17 may include an upwardly directed outer portion 18 and an inner portion 19 which forms a partition between the inner tube 14 and outer tube 15, thus closing off the space between the tube 14 and tube 15 to the bottom of the pot.

The partition 16 includes a portion 1Gb extending up wardly from shoulder 15a. Portion 16h has a plurality of circumferentially spaced openings 20' so that air passing upwardly through the tube 14 may pass outwardly into the space between the portion 16b and the tube 15. A cap 21 is fitted over the upper end of the portion 16h and includes an outer edge portion that is upwardly inclined as at 22 and which overlies the upper edge of the tube 15. It should be noted that the upper edge of the tube 15 is similarly inclined and spaced from the edge 22 so as to define a circumferentially extending, and upwardly and outwardly directed air passage 23.

The diffuser housing 15 is provided with a plurality of vertically spaced rows of apertures 24 which are adapted to deliver air, from the space within the housing 15, and below the partition 16, to the interior of the pot, at a relatively low pressure. The upper portion of the housing 15, above the partition 16, is provided with a plurality of closely spaced rows of air apertures 25. During use air Hows upwardly through the central air tube 14 and flows outwardly at relatively high pressure through the apertures 25. Part of this air flows downwardly into the expansion chamber defined between the inner tube 14 and outer tube 15 where it passes outwardly at a relatively lower pressure through the apertures 24. In practice, the parts and apertures are so proportioned that the air admitted through the pot side Wall, at high pressure through the

air inlets

5, 6, 7, 8 and 9, and the air admitted outwardly through the air apertures 25, is at the same pressure.

In practice, high pressure air through the

apertures

5, 6, 7 and 8 mixes with the vaporized hydrocarbon to produce a primary mixture. As will later be described, low pressure air from the apertures 24 maintains localized combustion which serves to heat the rising mixture. High pressure air through the apertures 9 and 10 provides the secondary air for producing the finally combustible mixture. And high pressure air from the diffuser housing above the partition 16 serves to complete and clean the combustion. In practice, the low pressure jets thus admitted provide a supply of air for a strictly localized combustion diagrammatically shown in FIGURE l2, and below described in greater detail. Thus, whereas the primary air admitted through

apertures

5, 6, 7 and 8 enters and forms part of a rich and incombustible mixture of air and vaporized fuel, the low pressure jets admitted through the apertures 24 support localized pinpoints of ame which are scattered across the surface of the outer air diffuser sleeve 15, and serve to heat the rich incombustible mixture as it rises in the pot, this heating having, in practice, a catalytic action.

An inverted conic baflie 26 is shown as supported on rivets 27 affixed to the pot wall. The baille 26 has a central opening 28 through which the air diffuser assembly extends. The balle 26 is shown with its lower rim generally aligned with the third row of air inlet apertures 7. Rivets 27a may be used to support a lower pilot ring, if one is desired.

Another relatively small bafiie member 29 may be affixed to the outer tube 15 at a level above the bafe 26 and at a level below the row of apertures 9. In effect, the

bales

17, 26 and 29 are interposed between the combustion taking place at and above the secondary air inlets 9 and the liquid f uel admitted to the circumferential trough 12. This liquid fuel is thus shielded from direct radiation of heat from the flame by the baffling shown in FIGURE l, or by other suitable bafliing, such as is shown, for example, in FIGURES 3 and 5. The liquid hydrocarbon in the trough 12 does not see the flame. The baffling can, of course, be varied, and the design of baffling shown is not critical.

FIGURES 3 and following illustrate a variant form of burner and pot which, however, has the same general function and mode of operation as that of FIGURES l and 2. Considering first FIGURES 3, 4 and 5, the burner includes an outer jacket 30 within which is suitably supported a burner pot having a side wall 32 and a bottom section 33 with an upwardly domed inner portion 34 which is upwardly continued at its center by the axial air tube 35. It will be clear that, as in the form of FIGURES 1 and 2, the pot structure defines a circumferential trough 36 which is adjacent the pot side wall. The fuel inlet pipe 37 delivers fuel to the trough 36, being aligned with a sump, generally indicated at 38, which constitutes a local deepening of the circumferential trough 36. Aligned above the sump 38 is a starting air inlet pipe 39 which is in communication with the space between the outer housing or jacket 30 and the pot side Wall 32. 40 indicates, generally, a starter assembly which is shown as including an inclined tube 41 which extends through a suitable aperture in the pot side wall and which has an inner end 41a which overlies the sump 38 or a lateral extension thereof, as will later be described in detail. 41b is an air inlet. With reference, for example, to the structure as shown in FIGURES 5 to 9, inclusive, the fuel inlet fitting 37 is aligned with the deepest sump portion 38a. Thus the fitting actually extends below the normal bottom level or surface 36 of the circumferential trough. This, in connection with the contour of the trough itself and the upwardly domed bottom, insures that a minimum volume of liquid fuel can enter the pot bottom if, for example, the fire is extinguished. The normal controls employed will halt the delivery of liquid fuel if the level of fuel within the pot rises as high as the top of the inlet fitting 37. This provides a relatively small maximum possible volume of liquid fuel in the pot bottom. The starting pipe or air supply means 39 is located immediately above the sump portion 38. The air inlet passage thus provided is positioned and sized to work automatically, with no closure needed and no control means. It provides an air jet of starting air directly over the sump portion into which the liquid fuel flows through the fitting 37. At the starting stage combustion takes place immediately above the surface of the oil in the sump, causing a rapid initial vaporization. The ratio between the infiow of air and the vaporized hydrocarbon becomes favorable for a noncombustion stage, as the volume of vaporized liquid fuel increases. In other Words, at the immediate starting period the air supply through the inlet 39 is secondary air, the primary air being suitably supplied through the starter assembly 40, which overlies the lateral shallower sump extension 38h. The details of this supply of primary air for the starting assembly are not shown, since that assembly does not form part of the present invention. Following the rapid vaporization of an increasing volume of the hydrocarbon, the air delivered through the tube 39 then becomes primary air and merely mixes with the rich mixture. At high fire it is just a small fraction 0f the primary air supply, and combustion no longer takes place near or immediately above the sump 38. On the contrary, the rich mixture rises in the pot and does not become combustible, at the high re stage, until it receives its secondary air through such inlets as, for example, 47 or 47a.

In the pot proper, as shown on a somewhat larger scale in FIGURE 5, it will be noted that the pot side wall 32 is provided with a lower row of primary air inlet apertures 42 which may advantageously be downwardly turned, and somewhat inclined from the radial, in order to impart a swirling movement to the air admitted therethrough. 43 indicates additional rows of primary air inlets which are spaced circumferentially about the pot side wall at Various distances from the ends of the pot. The pot side wall 32 is shown as terminating with a circumferential lip 32a. An upper pot section, generally indicated as 44, may be welded or otherwise secured to it as at 45. This separation is advantageous, since the strip or ring 44, which is subjected to maximum heat, may be made of stainless steel or other suitable heat resisting metal. Air is admitted through apertures 46 to the space about the pot side wall 32 and below the lip 32a. This results in the generally vertical direction of a stream or screen of air.

Referring, for example, to FIGURE 5, the pot side wall 32 is secured to the bottom 33 and constitutes, so far as heat conduction is concerned, a homogeneous unit. The pot is completed by the outer member or ring 44 which is welded or otherwise firmly secured to the pot side wall as at 45. The apertures 46 deliver air inwardly against the upper outer part of the pot side wall section 32. In effect an expansion chamber is provided and the jets of air impinge on the pot wall, and the result is the upward delivery below the secondary air inlets 47 of low velocity air. This low velocity air is delivered at the base of the jets owing from the inlets 47 or 47a. It will be understood that these secondary air inlets may be upset or upwardly inclined by distortion of the metal, as shown at 47, or they may constitute merely punching of the metal, as at 47a. It will be understood that, normally, the secondary air inlets of a particular pot will all be inclined, as at 47, or will all be straight punched, as at 47a. The point of importance is that, no matter how the secondary air jets are delivered, the upward delivery at relatively slow velocity of the air whichenters through the inlets 46 stabilizes the flame and prevents any vibration or utter. A slow speed supply of air, at all times well below the speed of flame propagation, is thus provided, and the flame from the secondary air jets burns right back to the surface of the member 44. The flame front is thus stationary and is located at the pot side wall, at the slot defined between the lip 32a and the upper outer pot member 44.

Mounted about the diffuser pipe 35 is the diffuser sleeve or housing proper 48. It is spaced outwardly from the sleeve 35, for example, by a bottom closure element 49. It is provided with a plurality of air outlets 50 through which air flows outwardly into the interior of the pot and into the mixture of primary air and vaporized fuel. The top supporting partition 51 centers and supports the upper end of the diffuser sleeve 48, and rests removably on the upper edge of the pipe 35. It is suitably apertured, as at 52, to permit air to tiow upwardly and outwardly from the upper end of the tube 35. The diuser sleeve 48 has a top closure 53 which defines a plenum chamber above the support or partition 51, this plenum chamber being indicated at X. The aperture 52 is of such size that the air within the plenum chamber will be generally at the same pressure as the air delivered to the space within the outer housing 30 of FIGURE 3 and the pot side wall 32. The partition Si, however, is provided with apertures, as at 54, which maintain the air in the space between the pipe 35 and the sleeve 48, and below the partition 51, at a somewhat lower pressure. Thus the air which escapes through the outlets 5t) is at lower pressure than the air delivered through the

primary air inlets

42 and 43, and is at a lower pressure than the air delivered outwardly through the closure cap 53 through such apertures as those shown at 55 and 56. Thus, as in the corresponding structure of FIGURE l, air at relatively high pressure is delivered from the plenum chamber X upwardly and outwardly into the rising mixture or into the combustion already taking place, whereas air at low pressure is admitted through the diffuser wall or sleeve 48. This low pressure air supports the localized pinpoints of flame illustrated diagrammatically in FIGURE l2, and heats and has a catalytic effect on the rising mixture.

With reference to the supply of air for combustion, there is illustrated in FIGURE 3 a motor 60 rotating the axially located fan 61. The fan assembly may be mounted i-u any suitable base 62 removably secured, as by securing means 63, to ythe bottom member 64 of the outer housing 30. 65 indicates a circumferential baiiie against which air isy delivered by the fan 61. The baie may be mounted, for example, on suitable brackets 66 which leave a bottom space 67 through which the air, after its speed has been broken by the circumferential baffle 65, is allowed to flo-w into the space between the ouiter sleeve or housing 30 and the pot side wall 32. To the extent that this air is spiralled by the fast action, it increases the ytendency to an inclined delivery through the inlets 42, which wil-l cause a spiralling rotation of the air def livered into `the Ilower part of the plot. The apertures 42 are shown, for example, in FIGURE 5. Positioned above the fan is a generally plane, horizt-onail bathe 70 which may be supported upon -a plurality of generally radial supports '71 which space the bafiie 70 from the upper plate 72 with its axial air inlet 73. Thus some of the air delivered by the fan is directed inwardly by the supports 7l and passes upwardly through the air inlet 73 for delivery through the tube 35. However, the supports '71 break up the spiralling of the ai-r, and the baiiies or plates 78 and 72 prevent 'any direct impingement on the bottom dome 34 or against the bottom wall of the pot, which might otherwise cause undesired cooling of the pot botto-m. The upper plate 72 is shown with an upper tubular extension 72a, so no air Wipes the pot bottom.

It will be realized that a wide variety ot" baiiiing within the pot may be practical. In the yform of FIGURES l and 2 two baiiies are employed, extending outwardly from the diffuser sleeve 15, and la single Ibaiiie is employed, as at 26, extending inwardly from the pot side wall, these baffles being in staggered relationship. In the form of FIGURE 5 only two baffles are employed, an upwardly and outwardly inclined baffle 75 on the diffuser wall 48 and a downwardly and inwardly extending conic baffle 7 6, shown as mounted on pins 77 on the pot side wall. The baffle 76, for strength and stability, is circumferentially channeled or beaded, as at 78. In FIGURE 13 `a bafiie 76a is shown, with two beads 78a. The ring 76 may be made solid, or may be divided for an overlap. If desired, as in larger burners, two or more of the beads or concavo-convex strengthening ribs 78 may be employed. In the form of FIGURE 5 the

baffles

75 and 76 are art the same level as an indication of the Wide variety of shape `and location of battle which is acceptable. They perform, however, generally the same function .as the baffles of FIGURE l, in that they partially or largely shield the fuel in the trough 36 and the sump 38 from seeing the combustion of the fuel. Thus the liquid fuel is vaporized not soy much by radiant heat as by heat conducted downwardly along the pot side wall or by the air diffuser assembly. This is not to say that no radiant heat is permitted to reach directly the liquid fuel. It is, however, of substantial advantage to limit, if not to prevent, the subjection of the liquid `fuel to radiant heat, thus preventing cracking of the fuel.

Referring to FIGURE 10, a somewhat different pot structure is illustrated, in which an `outer sleeve 100, with its lower wall 101, defines a space within which a circumferential, generally cylindrical, intermediate baflle 102 is positioned. Spaced inwardly from the baille 102 is the burner pot, generally indicated at 103, and having a central air Iduot 104. Since the details of pot and duct and diffuser structure have been shown, for example, in FIGURES 3, 4 and 5, they are not repeated in FIGURE 10, it being understood that the pot 103 and the duct 104 are preferably provided with air inlet and air diffuser means, generally as shown in FIGURE 5. The side wall or housing 100 is apertured to receive a duct 105. A fan assembly, including a motor and its fan, not shown, directs air inwardly against one side of `the circumferential baille 102. The air moves downwardly, in the direction of the arrows about the baille 102, and it all eventually passes upwardly through the axial air inlet 107 of the bottom baille 106. Some of this air moves directly upwardly into the diffuser duct or passage 104, and some of the air passes upwardly about the pot 103. Direct impingement against the pot bottom is prevented by the transversely extending intermediate baille 110 with its central aperture 111. Since the baille 110 terminates at its outer edge somewhat within the cylindrical baille 102 air can thus ilow upwardly about the outer edge of the baflle 110 and upwardly through its central aperture 111. If desired, radial supports 112 may be employed `between the bottom plate 101 and the horizontal baille 106. Thus, in FIGURE l0, air, instead of being fandirected upwardly along the axis of the pot, is directed laterally, but is so bailled that no local cooling of pot side wall or bottom takes place, Iand no pressure differentiation between the air delivered upwardly about the pot side wall 103, or upwardly through the diffuser duct 104. As will be clear from FIGURE l0, the horizontal baille 110 is downwardly spaced below the bottom, and the air delivered by the fan does not cause such cooling of the pot bottom as would cause puddling or prevention of adequate and uniform vaporization of the liquid fuel. Means such as the circumferential bead 110a prevent `any escape of lair between baille and pot bottom.

It will be realized that many changes may be made in size, shape, number and disposition of parts. Whereas there is shown and described several operative forms of the invention, it should be understood that these showings and descriptions should be taken yas primarily illustrative or diagrammatic. For example, the details of Ithe admission of both primary and secondary air may be widely varied. The, shape of the pot or the method of making the pot may be widely varied. For example, FIGURE 11 illustrates a variation in the formation of the upper edge of the pot. In FIGURE 5, for example, the pot side wall 32 terminates in a top circumferential upper lip 32a, and a supplemental separate member 44, which may be of heat resistant metal, -is secured to the pot side wall 32 somewhat below the lip 32a. In FIGURE ll, on the contrary, the pot side wall 132 is outwardly offset, as at 133, and inwardly offset, as at 134, terminating in `an upper cylindrical portion 135 and an outwardly extending ilange 136. A ring, generally indicated as 137, is fitted in and supported upon the unitarily formed ledge 133a of the pot side wall. It includes an upper sleeve 137a aligned with air inlets 133]). Thus air is directed upwardly toward the inward offset 134. The upper wall of the offset 134 is provided with a plurality of secondary air inlets 134g. The ring 137 also includes a lower portion 137b with an inwardly extending lip 137C upon which any suitable baille ring 137:1 may be supported.

In the pot of FIGURE 13 the formation of the bottom will be understood to be substantially the same as in the structure of FIGURE 5. It includes, for example, the domed bottom portion 200 which is shaped to define a circumferential trough 201 having a localized sump 202 in line with the fuel inlet fitting 203. Upwardly extending from the center of the domed bottom 200 is the air distributor pipe 205. In order to deliver starting air downwardly toward the sump there is shown a sheet metal guiding or directing element 206 aligned with an aperture 207 in the pot side wall and welded as at 208 to the inner surface of the pot side wall. Likewise, in the place of the supporting pins 77 of FIGURE 5 it is preferred to roll a circumferentially inwardly extending ilange 209 which may be formed when the sheet for the pot side Wall is rolled. It is also found to be advantageous to employ an upper pot component 210 suitably apertured for the admission of secondary air, as at 211, which, as shown in FIGURE 13, may be rolled into interlocking relation with the upper extension 212 of the pot side wall.

In the form of FIGURES 13 to 15, inclusive, the air diffuser unit is removably mounted on the tube 205, and is shown as including an outer, generally cylindrical wall 220 which may be rolled into interlocking relationship with a bottom member 221 and a partition 222. It will be observed that the lower outer ilange 221a of the bottom 221 is rolled into place and gripped between a bead 220a and a bottom ilange 220b. The outer ilange 222a of the partition 222 is held between beads 220e` and 220d of the side walls 220. The structure is completed by a perforated top closure 23 which may be rolled into the closed position in which it is shown in FIG- URE 14. Similarly, the baille 224 may be rolled into and received in the circumferential cavity 220e of the wall 220. The entire unit is thereby firmly held together in proper assembled position and may be applied to and removed as a unit from the air pipe 205. The aperturing of the pot of FIGURE 13 and of the diiluser may be, in general, the same as that shown in FIGURE 5. However, it is preferable to have a plurality of small apertures 225 in the top plate 223 which direct air directly upwardly. It will be understood that the details of perforation may be widely varied. In this structure, as in the structure of FIGURE 5, the partition 222 passes air at high pressure into the plenum chamber XX between the

members

222 and 223. Air is allowed through the partition 222 by apertures 222b into the space within the wall 220 and about the air pipe 205 under conditions which maintain the air within the air diffuser structure thus formed at a substantially lower pressure than the air which is delivered into the vaporized liquid fuel through the primary and secondary air inlets of the pot side wall. This is important in connection with the maintenance of the widely scattered small heating llames or pinpoints of combustion earlier described.

Referring to FIGURE 15, we illustrate a variation in the formation of the upper edge of the pot. The pot side wall 232 is inwardly rolled, as at 233, and outwardly offset, 4as at 234, and further offset, as at 235. Near the upper edge 232a the wall is outwardly rolled, as at 236. Fastened to the upper portion 232er, as by welding, is an angular ilange 237 for mounting the pot in the outer wall of the burner. Seated upon the out-turned portion 234:1 is a circumferential ring 238 which corresponds to the upper extension 212 of FIGURE 13.

The use and operation of the invention are as follows:

In burning liquid hydrocarbon fuels and, in particular, catalytic blends of hydrocarbon fuels, there is always a risk, for example, in pot type burners, of cracking the fuel and of producing free carbon which eventually soots up the burner, and either makes it unusable, or provides a difficult maintenance and cleaning problem. Disclosed herein is an improved structure and an improved method of liquid hydrocarbon combustion which substantially eliminates cracking. Considering, for example, the pot structure of FIGURE 5, liquid fuel is admitted to a trough 36 which extends circumfercntially about the pot bottom, and which is so near to the pot side wall 32 and its downward extension 33 that the heat of combustion taking place at or above the top of the pot is eventually conducted to the outer edge of the pot bottom, and is effective in connection with the vaporization of the liquid fuel. The axial diffuser assembly also conducts heat to the trough. In burners of the type herein shown the fuel is vaporized, during normal pot operation, by combustion taking place at or above the upper portion of the pot. In `considering the pot of FIGURE 5, or the pot of FIGURE 3, in full operation, air is delivered at uniform pressure upwardly about the pot side wall and upwardly through the air diffuser duct 35. The air which enters the pot through the

apertures

42, and 43 is what is commonly called primary air. It mixes with the fuel vaporized by combustion taking place above and produces a more or less homogeneous mixture of air and of vaporized hydrocarbon. The parts are so proportioned, however, that insufficient air is admitted through the primary air inlets to provide a fully combustible mixture. This `so-called rich mixture rises in the pot, and when it passes above the baiiles 7S and 76 it reaches the level where it receives secondary air in substantial volume. The details of admission of the secondary air, as such, may be widely varied, but secondary -air may be supplied, for example, through the inlets 47 or 47a of FIGURE 5 and is delivered into the rich mixture in sulcient volume and at sufficient pressure to provide a substantially homogeneous mixture of air and vaporized hydrocarbon in which the air lproportion is sufficient to support full combustion. In the structure of FIGURE the final and completed mixture will burn at or somewhat above the level of the lip 32a. Additional air may be supplied to the final mixture or to the llame, for example, through the apertures in the closure cap 53, to make sure that all the fuel is burned.

In carrying on this method of combustion, and especially with some of the modern fuels, the problem of preventing cracking is difficult. In accordance with the present invention it has proved advantageous to protect the liquid fuel largely, or substantially, from subjection to direct radiation from the burning fuel. This protection may be provided by the baffling shown, for example, in FIGURES l, 3 and 5. The baffles keep the liquid fuel from seeing the combustion taking place. However, it is important, in order to vaporize the fuel, that heat be available for adequate vaporization. Some heat is supplied by conduction downwardly through the pot Wall and through the air diffuser structure. However, this heat might prove insufficient if the fan-delivered air is permitted to wipe the pot bottom and to abstract heat from it. This theft of heat from the pot bottom would tend to cause puddling or accumulation of liquid fuel, and would substantially disturb the operation of the burner. It is found that adequate baffling is effective in preventing the fan-driven air from wiping heat directly from the pot bottom. One solution, in connection with the axially located fan, is shown in FIGURE 3, with the use of the circumferential cylindrical baffle 65 on the one hand and with the use of the baffling system 70 and 72 on the other, to insure that adequate air, at a substantially even pressure, flows upwardly about the pot side wall and upwardly into the air diffuser duct, without, at the same time, wiping heat from the pot bottom. Another solution, in connection with a side located fan, is shown in FIGURE l0. In both instances a supply of air is provided both for the exterior of the pot and for the 4interior of the pot at uniform pressure, and without the heat loss which would be caused by a direct wiping of high velocity air across the pot bottom.

An important phase of the invention is also the heating of the rising mixture. This heating, as earlier alluded to, is obtained by the use of an air diffuser formed to maintain pinpoints of flame over a widely scattered area. These pinpoints are maintained, as diagrammatically shown in FIGURE l2, by delivery of air at relativell lor-w pressure through the apertures 50 of the diffusing wall. In practice, these low pressure jets of air Zones of localized combustion.

pick up the rich mixture and convert it, but only locally, into a fully combustible mixture. Each such low pressure jet, as shown at B in FIGURE l2, draws a certain amount of the rich mixture from the localized space, indicated at C in FIGURE l2. The low pressure at which the air is delivered provides isolated and widely scattered With the diffuser wall 48 covered by these widely scattered flame pinpoints it becomes an effective heating means for heating the rising rich mixture, and actually has a catalytic effect. On the other hand, the high velocity high pressure jets of air delivered inwardly through the

primary air inlets

42 and 43 merely add air to produce a rich mixture, without localized combustion. This rich mixture is heated as it rises, by the pinpoint jets above discussed. The heat speeds up the chemical changes elsewhere mentioned. It does not burn as a whole until it receives enough secondary air, for example through the apertures 47, to be converted into a thinner and fully combustible mixture.

It is also found that in maintaining the method of combustion herein discussed it is highly advantageous to direct the lowest row of air inlet jets, as at 42 in FIG- URE 5, somewhat downwardly toward the bottom. These inlets may also be turned somewhat from the radial so that the jets cause the mixture to spiral or to rotate. To some degree the same effect may be obtained by causing the air to spiral within the space surrounded by the outer housing or sleeve 30. However, it is practical and advantageous locally to deform the pot side wall in such fashion as to cause the jets 42 to be directed at an inclination to the radial.

A further advantage of the present structure is to insure that there will be a minimum amount of fuel in the pot bottom in cases where the flame becomes extinguished and the burner is flooded. The upward doming of the bottom of the pot, and the location of the inlet or fitting 37 in line with the sump 3g, insures that if combustion ceases only enough liquid fuel can enter the pot to fill the trough 36 to a relatively low level. The controls currently used operate to cut off fuel flow when the fuel gets as high in the pot as the top of the fuel inlet.

A further advantage of the structure herein described is to prevent any difliculty with downdraft and eddy currents which tend to cause poor combustion and carbon build-up. The air diffuser structure herein shown, including, for example, its outwardly extending baffles, blocks out the `central space of the pot and positively prevents any axial or near axial downdraft. 'Ihe local combustion taking place at the outer surface of the diffuser sleeve 48 also promotes an upward movement of the mixture. The products of this limited combustion tend to rise and to carry with them the unburned mixture. The slight upward flow of air along the diffuser counteracts the weak eddy currents along the under side of the secondary air jets and thus prevents downward flow and carbon build-up. Thus the air diffuser or flame propagator helps the action of the pot in several different ways.

It should be kept in mind that when air is rotating rapidly in a cylinder centrifugal force tends to make it hug the outside wall, and there is little air movement or pressure at the center. According to the method and structure herein shown, the lowest row of primary air inlets 42 cause a rapid rotation of the mixture in the lower part of the pot. Hence, the importance of applying air at uniform pressure both about the exterior of the pot and upwardly through the interior of the pot, this -result being obtained by the baflling structures described in connection with FIGURES 3 and 10. The baffling can, of course, be widely varied.

A further advantage of the burner structure shown herein, for example, as shown in FIGURE 5, is that it produces a flame of relatively small vertical extension. In practice, it is from ten to twelve inches lower in Vertical clearance than the llame of existing pot type burners of the same size or capacity. This is, in practice, very important, since it permits the heater or stove designer to employ a heating structure of substantially lower vertical clearance. In the past, the height of the flame has been a critical limiting fatcor, for example in oor furnaces, since, of course, it is not, in general, practical to employ heaters or stove structures in which the flame regularly impinges on the upper 'wall of the stove. The ame of lower height permits the heater designer considerable latitude, and enables him to design heater or stove units which can be tted into more restricted spaces, particularly as regards vertical clearance. This is very important, for example in Hoor furnaces.

To summarize, liquid fuel is supplied to a circumferential trough preferably adjacent the side wall of the pot. The fuel is vaporized largely by conduction of the heat of combustion downwardly through the pot side wall or through the diffuser structure. Cracking is prevented by the baiing which shields the liquid hydrocarbon from seeing the flame. This loss of radiant heat otherwise available for vaporization is kept from being damaging by a careful shielding of the pot bottom from the direct effect of rapidly moving air. The rich mixture formed by the addition of air to the vaporized hydrocarbon is heated as it rises in the pot, and, at the same time, downdrafts and downward eddy currents are prevented. The rich mixture is converted rst into an alcohol and then into an aldehyde, as it rises in the pot, and finally reoeives adequate secondary air for full combustion. These chemical changes are speeded up by the heat of the diffuser, which has practically a catalytic effect.

We claim:

l. A method of controllably Vaporizing and burning liquid hydrocarbon fuels in a confined chamber which includes the steps of admitting liquid hydrocarbon fuel to a lower portion of the chamber, vaporizing and oxidizing the liquid fuel without cracking, at a temperature substantially below the final combustion temperature, by admitting primary air to the chamber in volume insufficient to form a fully combustible mixture, while protecting the rich primary mixture of air and vaporized fuel thus formed from direct subjection to the radiant heat of combustion taking place elsewhere in the burner, Simultaneously heating the rising rich mixture of vaporized fuel and air by maintaining limited localized combustion jets along the path of ow of the rising mixture, the air for said combustion jets being delivered at a pressure substantially below the pressure of :the primary air and inducing final combustion of the now homogeneous and heated mixture of air and fuel by the admission of secondary air to the rising mixture adjacent the upper portion of the burner.

2. The method of controllably vaporizing and burning liquid hydrocarbon fuels in a conned chamber which includes the steps of admitting liquid hydrocarbon fuel to a circumferentially extending zone in the lower portion of the chamber, such zone being radially spaced about the center of the chamber, subjecting the liquid fuel in such circumferential zone to a temperature suicient to vaporize the liquid fuel without cracking it, supplying air to t-he initially vaporized hydrocarbon in a quantity less than that required for combustion, while imparting a rotary motion to said mixture of vaporized fuel and air as it moves in and upwardly from the zone of initial vaporizetion, thereafter continuously directing air into the mixture as it rises upwardly in the chamber, heating the rising mixture by localized areas of combustion in its path, and converting it first to an alcohol compound mixed with vaporized hydrocarbons and, thereafter, during the subjection to further air and heat to an aldehyde compound, the air used for maintaining the localized yareas of combustion being delivered at substantially lower pressure than the air added to the mixture in the course of its conversion to an alcohol compound and thereafter to an aldehyde compound and supplying secondary air to the final aldehyde compound in volume sucient to render it fully combustible and burning the mixture thus formed at and above the level of admission of such secondary air, while preventing central downdraft through the chamber and while substantially shielding the hydrocarbon in the initial circumferential zone of vaporization from seeing the combustion of the nal mixture.

3. An hydroxylating pot type liquid fuel burner which includes a burner pot having a pot side wall with apertures circumferentially and vertically spaced therein for the admission of primary air to the interior of the pot, and means for delivering secondary air into the pot at a level above the uppermost row of such apertures, means for admitting liquid fuel to a depression extending circumferentially about the bottom of the pot and adjacent the pot side wall, whereby liquid fuel in such depression is subjected to heat conducted downwardly by the pot side wall, an air delivery and mixture heating assembly positioned generally along the axis of the pot and formedl and adapted substantially to prevent downdraft in the pot and to conduct heat to the pot bottom, said assembly including an air admission tube and a surrounding perforated air diffuser, means for delivering air through the apertures of said diffuser and into the mixture of air and vaporized hydrocarbon rising in the pot at a pressure lower than the air pressure at which primary and secondary air is added to the mixture through the pot side wall, the air coming through the apertures in the difuser combining with the fuel and `air mixture to maintain localized combustion on the surface of the diffuser which is effective to heat the rising mixture, and baffling means for substantially shielding the liquid fuel in Said circumferential zone from seeing the combustion of the nal mixture taking place at and above the level of admission of air through said secondary air inlet apertures.

4. The structure of claim 3 characterized in that the air admission tube of the mixture heating assembly is in communication with the space below and about the burner pot.

5. The structure of claim 3 characterized in that the air delivery vand mixture heating assembly includes means located above the level of the secondary air inlet apertures for delivering air to the mixture at substantially the same pressure as that of the primary and secondary air.

6. The structure of claim 3 characterized in that the air ldiffuser includes means for dening a chamber having one or more air inlet apertures in communication with the air outlet apertures through which air may pass to the interior of the pot, the area of the air outlet apertures substantially exceeding the area of the air inlet aperture or apertures.

7. The structure of claim 3 further characterized by means for delivering air to the space about the pot side wall and to the air admission tube with a minimum cooling of the pot bottom including a fan located below the pot bottom and means for rotating it, a generally horizontal baffle plate overlying the fan and located between it and the pot bottom, a circumferential air defiector in the line of delivery of the fan, passage means for permitting a flow of air about said deector to the space about said pot wall, a second generally horizontal plate positioned between the pot bottom and the horizontal b-aie plate, said plate being axially lapertured in communication with said air admission tube, the space be tween said plates being in communication with the space within said circumferential air deflector, whereby the fan delivers air simultaneously to the space about the pot side wall and to the air admission tube.

8. The structure of claim 3 further characterized in that said baffling means includes a bafe in the form of a somewhat concavo-convex frustrum, said bafe having one or more circumferential beads extending thereabout, and means for supporting said bale including a circumferential bead formed in the pot side wall.

9. 1n a pot type burner having a circumferential pot side wall .apertured to permit the entry of air for combustion, a bottom element defining a circumferential trough, a sump in said trough, a fuel inlet fitting in the pot side wall at said sump extending below the normal level of the trough, an ignition assembly extending inwardly through the pot side wall and having a lower end terminating above .the sump, the portion of the sump underlying the ignition assembly being somewhat shallower than the portion of the sump in radial alignment with the fuel inlet fitting, the pot bottom surrounded by the t-rough being upwardly domed to an elevation substantially above the plane in which the fuel inlet fitting lies, whereby a minimum volume of liquid fuel is present in the trough and pot bottom when the level of fuel in the pot bottom reaches the level of the top of the fuel inlet aperture through said fitting, and means for directing starting air downwardly toward said sump.

10. The structure of claim 9 characterized in that the means for directing starting air downwardly toward the sump is constituted by a tubular member within the pot side wall, the interior of which is in communication, through the pot side wall, with outside air, said tubular member having a lower end spaced somewhat above the level of fuel in the sump.

l1. The method of controllably vaporizing and burning liquid hydrocarbon fuels in a confined chamber which includes the steps of admitting liquid hydrocarbon fuel to a circumferentially extending zone in the lower portion of the chamber, such zone being radially spaced about the center of the chamber, subjecting the liquid fuel in such circumferential zone to a temperature sufficient to vaporize the liquid fuel Without cracking it, supplying air to the initially vaporized hydrocarbon in a quantity less than that required for combustion, while moving such vaporized fuel and air in and upwardly from the zone of initial vaporization, thereafter continuously directing air into the mixture as it rises upwardly in the chamber, heating the `rising mixture by localized areas of combustion in its path, and converting it lirst to an alcohol compound mixed with vaporized hydrocarbons and, thereafter, during the subjection to further air and heat to an aldehyde compound, the air for the localized areas of combustion being delivered at a pressure substantially below the pressure of the air supplied to the initially vaporized hydrocarbon, and supplying secondary air to the iinal aldehyde compound in volume suicient to render it fully combustible yand burning the mixture thus formed at and yabove the level of admission of such secondary air.

References Cited in the file of this patent UNITED STATES PATENTS 2,240,861 Sabins May 6, 1941 2,262,922 Castle et al Nov. 18, 1941 2,290,544 De Lancey July 21, 1942 2,295,799 Focke et al. Sept. 15, 1942 2,369,999 Behrendt et al. Feb. 20, 1945 2,373,814 De Lancey Apr. 17, 1945 2,382,419 Huston Aug. 14, 1945 2,535,923 Hill Dec. 26, 1950 2,581,238 Cauley Jan. 1, 1952 2,625,214 St. John et al. Ian. 13, 1953 2,646,110 Horne July 21, 1953 2,855,031 Miller et al Oct. 7, 1958 FOREIGN PATENTS 202,133 Australia Dec. 22, 1955 216,523 Germany Nov. 23, 1909 293,289 Switzerland Dec. 1, 1953