US2537966A - Pot type oil burner with pilot chamber - Google Patents

Description

Jan. 16, 1951 N. H. CARGILE ET AL 2,537,966

POT TYPE OIL BURNER WITH PILOT CHAMBER Filed Feb. 28, 1942 2 Sheets-$heet 1 INVENTORS 33 Ncu. H. CARGILE Ccmusuus B. CLEMzrson MARCUSv L ELSON E 5 mug 22M;

'iTORNEY I Jan. 16, 1951 N. H. CARGILE ET AL 2,537,966

POT TYPE OIL BURNER WITH PILOT CHAMBER Filed Feb. 28, 1942 2 Sheets-$heet 2 o o u u o o canal 4 0000000 0 a o o oo o 0on0 cocoa INVENTORS El N51". H. CAnmu:

Conucuus B. cLelinersou Manna/gill: i 4 IE TORNEY Patented Jan. 16, 1951 UNITED STATES PATENT OFFICE POT TYPE OIL BURNER WITH PILOT CHAMBER of Tennessee Application February 28, 1942, Serial No. 432,812

Claims. 1

The present invention relates ot fuel burners, and more particularly to a liquid fuel or oil burner of the type employing a combustion pot.

It is desirable to maintain a pilot flame in the pot and heretofore it was the usual practice to interpose a baffle, in the form of a ring, intermediate the top and bottom of the pot. This baffle extended inwardly from the side walls of the pot and a flame of low heat value was maintained immediately adjacent the inner edge of this ring. However, it has been found in actual practice that, under certain circumstances, this heat, although of low value, was excessive.

It is also desirable to maintain, in addition to a high flame and a pilot flame, a flame or flames of intermediate heat value. The present invention is directed to a type of oil burner which produces the aforementioned desirable characteristics.

In the present invention a mixing chamber is disposed adjacent the closed bottom of the combustion pot and is so arranged as to function as a pilot and it also maintains the bottom wall of the combustion not at fuel vaporizing temperature. One of the objects of the present invention is to so construct and fashion a bathe, in that type of fuel burner employing a pilot flame mixing chamber at the bottom thereof, that a clean, steady, and efflcient flame can be maintained adjacent the inner edge of the baffle,

Another object of the present invention is to provide a baffle which extends only partially about the inner circumference of the burner whereby a relatively large area of the bottom part of the burner is exposed directly to the radiant heat of the flame when combustion takes place above the baffle.

Another object of the present invention is to provide for the steady and uniform flow of sec ondary air when the flame is burning at or adjacent the upper part of the burner. In carrying out this object, it is a further object of the present invention to utilize a large number of small holes in the upper part of the pot for supplying and metering secondary air added to the In the drawings:

Fig. l is a fragmentary view, partly in. section, of a space heater employing the present inven tion;

Fig. 2 is a view, in section, and on a larger scale, of the fuel burner shown in Fig. l, the view being taken on line 2-2 of Fig. 3;

Fig. 3 is a view, in section, taken on line 3-3 of Fig. 2;

Fig. 4 is a fragmentary, sectional view of a side wall of the combustion pot of the fuel burner showing one of the primary air inlet openings which leads into the pilot flame mixing chamber; and,

Fig. 5 is a sectional view taken on line 5-5 of Fig.2.

Referring to the drawings, for the purpose of illustrating one form of the invention, there is shown a space heater indicated generally at 20'. In this particular embodiment of the invention; the space heater is shown as comprising a cylin drical sheet metal casin 2i mounted on a ringlike base 22, having openings 23 for admitting air underneath the heater. The casing 2| is closed at the top by a wall 24 and at the bottom there is provided a wall 25 having a central opening 26. A flue pipe 2! is provided at the rear of the cas ing and a door 28 is provided at the front through which door access may be had to the interior of the casing. A fuel burner 30 is disposed within the casing.

The burner 30 comprises a combustion pot 3| having cylindrical side walls 32 and a slightly.

concaved bottom wall 33. This pot can be formed of either sheet metal or metal casting. The combustion pot is supported in the casing by a laterally extending flange 34 formed about the top of the combustion pot, which flange rests upon the top surface of a ring 35 which is secured to the side walls 2| of the casing.

An inwardly extending bead 31 is formed adjacent the top of the side walls 32 and this head is formed by rolling the side walls inwardly when the sidewalls are formed of sheet material. The bead 31 removably supports a ring-like lower burner plate 38. The outer edge of the burner plate is preferably arcuate in shape and slopes downwardly and inwardly so that the outer edge of the plate rests upon the upper part of the bead 31. The curvature of the bead and the outer edge of the plate 38 are such that contact is made between the edge of the plate and the upper surface of the bead throughout the entire circumference of the plate, although the circumference of the bead and plate may change because of rela- 3 tive differences of expansion between the materials of the side walls and the plate. Thus, an effective seal is maintained under all conditions at the joint between the plate 33 and the bead 35. The plate 33 is provided with a central opening 39. tral opening M5 in a ring-like upper burner plate 42. the side walls 32 and is provided with a bead or projection at on the under side thereof, which is utilized for locating the plate 42 and for main taining the same in position.

It will be noted from Fig. 2 that the plates 33 and 42 are spaced from one another. The top surface of the plate 33 slopes downwardly and outwardly from the opening 39 while the bottom surface of the plate 48 slopesupwardly and out wardly from the opening it. Thus, the plates provide an annular chamber t5 which is enlarged or spread adjacent the outer peripheral edges and restricted at the exit or mouth it of the chamber. The side walls S2 of the pot are provided with a plurality of air inlet openings 4'! which lead directly into the chamber 35, and air from the space 43 surrounding the burner to enters the chamber through these openings ll. Air is supplied to the space Q3 through a passage formed by the openings 23 in the base 22 and the opening 26 in the bottom wall 25. Preferably, two rows of holes are provided leading to the chamber 45 and these holes are of such size and number as to meter the quantity of air to be delivered through the mouth so. The air entering the chamber is permitted to spread in the'spreading chamber 45, and since the mouth 46 is restricted and disposed relatively remote from the openings all, the air passing through the mouth 46 flows steadil at a uniform pressure value throughout the entire mouth; in other words, the streams of air entering the side walls are dissipated since they are spread in the spreading chamber and then the air is confined as it passes through the mouth i i. Due to the slope of the underside of the plate 612 and the slope of the upper side of plate 38, the air will be directed in a generally horizontal direction and since the burner is cylindrical in shape, the air will flow inwardly in a generally horizontal direction.

The burner plates 38 and 42 merely rest, respectively, on the bead 3? and flange 3 1 and therefore, they can be removed readily from the burner and through the door 23 when it is desirable to have access to the interior of the burner. II" desirable, the plates 38 and 22 may be formed in sections to facilitate the handling thereof.

Although the burner plates 38 and 42 are referred to as ring-like in shape and the chamber is referred to as annular in shape, it will be understood, by those skilled in the art, that if the pot is rectangular or oblong in horizontal cross section, the ring-like burner plates and the annular chamber would also be rectangular or oblong.

Fuel oil is supplied to the bottom wall as of the combustion pot through a pipe Q9; this pipe extends through an opening in the side wall of the pot and adjacent the bottom thereof. A portion 58 of the bottom wall or" the pot, adjacent the outlet of the pipe 49, is depressed to form a spreading area for the oil; this depression is shown at 5!. Oil, upon entering the pot,

spreads over this area in a thin layer. The flow of fuel to the combustion pot is controlled by a This central opening is aligned with a cen- Burner plate 52 rests upon the flange 34 of valve mechanism indicated generally at 52 and which is shown diagrammatically, but it is to be of any construction which will meter the flow of oil flowing from a source of fuel through a pipe 53 to the pot.

It is desirable to maintain a pilot flame within the combustion pot 3E! so that when the heater is to be rendered effective as such, it is necessary only to increase the flow of oil to the burner. If desirable, this increase in flow may be accomplished by controlling the valve mechanism 52 by any well known device responsive to the temperature in the space to be heated.

The pilot burner for maintaining a pilot flame at the bottom of the pot is substantially the same as that shown in the application of Neil H. Cargile et al., Serial No. a20,698, filed November 27, 1941. The pilot burner 54 comprises a housing 55 which cooperates with the side 32 and bottom wall 33 of the combustion pot to form a mixing chamber 55. Preferably, the housing 55 is formed of cast metal and includes two vertically extending side walls 58 and a top wall 59 interconnecting the two side walls. The side walls 58 converge and top wall 59 slopes toward one end of the chamber 55 and the inner edges of the side and top walls form an outlet 6%. The opposite or outer end of the top wall 59 of the housing 55 is arcuate, the arcuate end having substantially the same curvature as the side walls of the combustion pot. The rear center of the top wall 59 is provided with an upwardly extending boss 62 which abuts the side walls 32, and the rear upper corners of the housing are provided with flanges 53 in the form of open bottom hooks which are forced over pins 64 fastened to the side walls 32. The boss 62, flanges 63, and pins 54 are provided for locating and holding the housing in position. The lower edges of the side walls 53 of the housing 55 rest upon the bottom wall of the combustion pot and the pins 6d are so disposed for holding the housing that the chamber 53 overlies substantially the entire depression El in the bottom wall 33 so that substantially all oil within this depression is confined within the mixing chamber while the burner is operating on pilot flame. Preferably, the housing 55 extends toward the center of the bottom wall of the pot. Thus, the mixing chamber 56 is formed by the walls of the housing 55, a portion of the side wall of the combustion pot and the bottom wall of the pot, and, since the side walls converge and the top wall 58 slopes downwardly, the cross sectional area of the chamber 55 gradually diminishes toward the outlet thereof.

The side wall 32 is provided with a plurality of air inlet ports 53 immediately below the junction of the top wall 59 of the housing and the side wall of the pot. These holes 66 are arranged in a horizontal row throughout substantially the entire width of the outer end of chamber 56. These ports 56 have their axes inclined downwardly, as is clearly shown in Fig. 4, for directing streams of air downwardly toward the outlet Si] and in paths converging toward said outlet. Since the streams of air entering the chamber are directed inwardly and downwardly and since the side walls and top and bottom walls converge, eddy currents cannot be created as would be the case if the air streams were to strike the walls of the housing obliquely. Also, the housing 55 is formed so that the longitudinal junctions of the walls thereof are rounded for preventing eddies of air in the chamber.

A horizontal row of ports 68 is formed in the eide wall 32 of the pot immediately above the edge of the top wall 59 of the mixing chamber. A horizontal row of ports 55 is disposed in substantially the same horizontal plane as the row of ports 56 and extends about the pot substan tially from one side wall 58 to the other side Wall 58 of the mixing chamber 55. Four horizontal rows of ports 15, spaced vertically with respect to one another, are provided in the side walls 32 intermediate the ports 58 and the head 31.

A baffle 12 is interposed in aplane intermediate the horizontal plane of the ports 68 and 69. This bailie is substantially c-shaped or arcuate and it is supported by legs 15 and 14. burner, in the embodiment illustrated, is cylindrical in shape, the baifie is formed arcuate to conform substantially to the side walls 32 of the combustion pot. The ends of this baffle 72 terminate adjacent the mixing chamber 55 so that the baffle will not shield any of the top wall of the chamber 55 from radiant heat of the flames. Thus, the mixing chamber .56 lies between the vertical planes of the ends of the baffle 72 so that the top wall thereof will be heated by radiant heat from the flames in the pot or at the top of the pot.

In operation, when the burner is first started, fuel is admitted to the bottom wall of the combustion not through the pipe 49 and there it is ignited by dropping a match or other flaming object into the pot through the door opening in the casing 2|. At first the fuel burns on the bottom wall of the combustion pot and as the temperature of the bottom wall increases, vaporization y of the fuel increases and the flame will then burn at the inner edge of the bafiie 12. If desirable, the flame can be maintained at or slightly above the inner edge of the bafile by restricting the flow of fuel to the pot to the proper amount. At this time, primary air is supplied to the fuel vapors through the ports 59 and secondary air is supplied through the upper ports 10. Under certain conditions, visible combustion will take place immediately above these ports 69. It will be apparent that the entire sloping top wall 59 of the mixing chamber will be subjected to the radiant heat of these flames, which heat is transmitted to the fuel and air inside the mixing chamber.

If it is desirable to slightly increase the heat value of the flame, it is necessary only to increase the supply of fuel oil to the burner and the flame will burn at varying levels within the pot above the baffle 12, the levels of the burning depending upon the quantity of fuel delivered to the pot. It will be understood that the radiant heat from these higher flames, together with the other heat, vaporizes the fuel on the bottom wall 33 and also heats the housing 55.

When a predetermined amount of fuel is delivered to the pot, all visible combustion will take place at or above the burner rings 38 and 42. Under this condition, primary air is supplied through the ports 69, 68, and Ill, and a steady, uniform flow of secondary air is supplied through the mouth formed by the plates 35 and 42. When the burner is thus operating at high flame, the lower plate prevents the secondary air from flowing downwardly into the pot and a clean, steady flame is maintained at or above the burner plates.

Likewise, the .baiile 12 prevents the air currents entering through the ports Ill from passing downwardly, and thus prevents disturbing air currents below the baffle 12 during the period of time that Since the oil the center of the bottom of the pot.

the burner is being started or while the flame is maintained at or above the inner peripheral edge of the baffle 12.

When .it is desirable to reduce the heating or high flame to a pilot flame, the valve mechanism 52 is adjusted to reduce the flow of fuel to the burner to two or three cubic centimeters per minute. This reduction in fuel supply causes the flame to descend in the combustion pot and it is then maintained at the outlet of the mixing chamber 56. This flame will be relatively small and steady. Combustion of fuel starts underneath the housing 55 and the flame projects slightly from the outlet and slightly over the bottom wall 33 of the combustion pot. It has no tendency to lick back into the mixing chamber or over the top of the housing 55. This extreme-. 1y clean and steady flame is assured by forming the mixing chamber and directing the air into the same so that the velocity of the air and gases are gradually increased as they approach the outlet 60. The bottom of the depression 5| in the bottom wall 33 is preferably horizontal and is tapered toward the center of the pot. Oil entering the pot is spread in a thin layer and flows within the depression toward the center of the pot. Thus, the oil presents a relative large surface subjected to heat and air and therefore is vaporized readily. The secondary air for completing combustion of the fuel, at the time that the pilot flame is maintained, is supplied partially by ports 63 and partially by ports 59. Thus, ample air is provided at the outlet 55 to complete combustion and maintain the flame spread over In actual practice, if any carbon is deposited in the burner while the burner is operating on pilot flame, such carbon is dissipated on the succeeding higher flame operation.

By the improved mixing chamber, a small steady flame can be maintained, and it can be directed where it is most useful; namely, onto the bottom wall of the pot. Since the bottom of the pot can be maintained above oil vaporizing a temperature, all oil delivered into the pot, including the increased quantity delivered thereto upon increased demand for heat, is quickly vaporized.

In this manner, the transition period between pilot flame and higher flames takes place quickly without the puddling of the oil on the bottom of the burner, which puddling usually causes an objectionable smoky flame.

It is highly desirable to subject the fuel on the bottom of the pot to a large amount of radiant heat when the burner is operating on higher flame so that heavier fuel is vaporized quickly. By fashioning the baffle 12 as herein shown, the entire top of the housing 55 is exposed to radiant heat at all times and in this manner heat is readily transferred from the top of the housing to the oil therebelow for assisting materially in vaporizing the fuel. In a larger type burner, for example, one in which the diameter in the combustion pot is twelve or thirteen inches, it has been found advantageous to extend metallic fins or vanes 16 from the top wall 55 of the housing for assisting in conducting heat from the top wall to the air, gas, and fuel within the chamber 56.

In addition to fashioning the baffle 12 so that it does not shield the housing 55 forming the mixing chamber 55 from the radiant heat, it has been found, in actual practice, that there is a relatively rapid transition period between pilot flame and complete combustion at the edge of or above the baflle 72 and in actual practice it has been found that by the arrangement as herein shown, the transition period between the pilot flame and higher flame is materially reduced over that in burners heretofore in use in which a baflle was employed within the combustion pot for producing a low flame. It will be observed that the volumetric capacity of the lower part of the burner in a plane below the baffle 12 has been materially reduced by the inclusion in the pot of the housing 55 and the chambe 56 formed thereby. Thus, when an increased quantity of fuel is delivered to the bottom wall of the pot, when changing from pilot flame to higher flame, the fuel mixture is brought quickly to a completely combustible state because the flame size has been materially increased whereas the volume of the space for mixing the fuel is rela tively small when compared with the usual type of pot burners. Hence, the transition period is not only reduced by maintaining the bottom of the pot above vaporizing temperature but also by reducing the quantity of mixture to be brought to a completely combustible state. We have found in actual practice that when a pilot vaporizing chamber as herein shown is employed, the best results, namely the securing of a short transition period between the pilot flame and higher flames, and a clear, steady, high flame, are produced by arranging the baflie if so that its ends terminate adjacent each side of the mixing chamber 56.

The. present disclosure is that of a burner hav ing a diameter of ten inches. The ports :4! are formed by a number forty-two drill. There are eighty-two equally spaced ports in the upper of the two rows and one hundred sixty-four in the lower row. The centers of the ports 4! of the top row thereof are spaced three-eighths Of an inch below the top of the flange 3d. The centers of the holes in the lower row of holes ii are three-sixteenths of an inch below the centers of the openings in the upper row. The centers of ports iii in the upper most row thereof are spaced approximately one and five-sixteenths of an inch from the bottom of flange 3G. The ports '10 of the next row below are spaced one and five thirty-seconds of an inch, from center to center from the top row of ports is; likewise, the third row of ports is spaced the same distance from the second row. The lower row of ports iii is spaced one and three thirty-seconds of an inch below the third row. Each of these rows includes twenty-six equally spaced ports in formed by a number forty-two drill. The ports in adjacent rows are staggered with respect to one another. The horizontal plane through the centers of the ports 68 is approximately seven-eighths of an inch above the plane of the centers of ports 66. These six ports 68 are spaced approximately one and two-tenths of an inch apart and they are formed by a number thirty-four drill. The ports 5 6 are spaced apart one-half of an inch and they are formed by a number forty-two drill, fifteen of these ports being provided. There are eighteen ports 59 which are equally spaced and are formed by a number thirty-four drill. The horizontal plane of the center of these ports lies one and five thirty-seconds of an inch below the horizontal plane of the center of the lowermost ports ID.

Since the burner plates 38 and ii] merely rest on the bead 3i and flange 34, respectively, they may be removed readily by merely lifting the same from their normal positions. Thus each of the plates 38 and 40 may be formed as a single ring,

8 if desirable. Likewise, baflie T2 and the legs 13 and 14 may be formed integrally since this de-' vice can also be removed bodily through the upper part of the burner after the plates 38 and 40 are removed. It will be seen, particularly from Fig. 3, that the baflie can be shifted slightly, while being lifted, and that it will then clear the bead 31.

Although we have illustrated the present invention in connection with a natural draft burner system, we have found the same is applicable to a system in which air, for combustion purpose, is forced through the burner and that all the advantages herein disclosed are present also in a forced air system.

While the form of embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted, all coming within the scope of the claims which follow.

We claim:

l. A liquid fu l burner comprising, in combination, a combustion pot having generally upright side walls and a connecting bottom wall, said side walls having upper and lower perforations, said pot being open at the top; means including side walls and a connecting top wall forming a substantially horizontally extending fuel vaporizing chamber disposed within the pot adjacent the bottom wall thereof, said chamber having an air inlet end, said air inlet end being disposed adjacent one side wall of the pot and communi eating with certain of said lower perforations, said chamber having a fuel mixture outlet con-' fronting a side wall of the pot opposite said first mentioned side wall, said outlet being disposed below the lowermost perforations in said pot; means for supplying liquid fuel to the chamber the top wall of said chamber forming means being disposed for directing all of the fuel mixture emanating from the mixture outlet along the bottom wall of the pot whereby the pilot flame burns directly over the bottom of the pot; and gas and air baffle means intermediate the top and the bottom wall of the pot and extending inwardly from said confronting side wall toward said first mentioned means and located between said upper and lower perforations.

2. A liquid fuel burner comprising, a combination, a combustion pot having side walls, said side walls having upper and lower performations, and a bottom wall, said pot being open at the top; means including a top wall and connecting side walls forming a fuel vaporizing chamber for a pilot flame disposed adjacent the bottom wall of the pot and extending inwardly from one side of the pot, said chamber having an air inlet and a fuel mixture outlet, the top wall of said chamber forming means sloping downwardly and inwardly and said fuel mixture outlet being disposed below the lowermost perforations in said pot; means for supplying liquid fuel to the chamber; and gas and air baiiie means intermediate the top and the bottom wall of the pot and at a higher level than the outlet of the chamber and disposed on the side of the pot confronting the first mentioned side and having the ends thereof extending toward the terminating adjacent the chamber.

3. A fuel burner comprising in combination, a combustion pot having bottom and side walls, the latter walls having vertically spaced air admitting openings, a housing having top andside walls disposed in the lower part of the pot, said housing cooperating with portions of said pot walls to form a vaporizing chamber having an outlet communicating with the interior of said pot, means for introducing liquid fuel into said chamber, certain of said air admitting openings in said side walls communicating with said vaporizing chamber, the top wall of said housing sloping downwardly inwardly and said outlet being disposed below the lowermost air admitting openings in said pot, and horizontal bafiie means in said pot between vertically spaced air admitting openings, said bafiie means being disposed at a higher level than the outlet for said chamber.

4. A fuel burner comprising, in combination, a combustion pot having bottom and side walls, the latter walls having vertically spaced air admitting openings, means having a top and converging side walls disposed in the lower part of the pot, said means forming a vaporizing chamber having an outlet communicating with the interior of said pot, means for introducing liquid fuel into said chamber, the top wall of said chamber forming means sloping downwardly inwardly and said outlet being disposed below the lowermost air admitting openings in said pot, and bafiie means extending inwardly in said pot between vertically spaced air admitting openings, said bafiile means being spaced from and disposed in a plane above said chamber outlet.

5. A fuel burner comprising in combination, a combustion pot having bottom and side walls, the latter walls having vertically spaced air admitting openings, a housing having top and side walls disposed in the lower part of the pot said housing extending inwardly from one side wall of the pot and cooperating with portions of said pot wall to form a vaporizing chamber having an outlet oommunioatingwith the interior of said pot, means for introducing liquid fuel into said chamber, certain of said air admitting openings in said pot side wall communicating with said vaporizing chamber, the top wall of said housing sloping downwardly inwardly and said outlet being disposed below the lowermost air admitting openings in said pot, and an arcuate bafile disposed in said pot above said chamber outlet and the lowermost air admitting openings in said side walls, said bafiie being disposed on the side of the pot confronting the first mentioned side and having the ends thereof terminating adjacent said housing whereby air entering the pot immediately above the housing may pass between the ends of the bafiie.

NEIL H. CARGILE.

CORNELIUS B. CLEMETSON.

MARCUS L. NELSON.

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

UNITED STATES PATENTS- Number Name Date 1,004,040 Laizure Sept. 26, 1911 1,806,566 Sturgis May 19, 1931 1,810,035 Valjean June 16, 1931 1,975,266 Gambell Oct. 2, 1934 1,984,573 Frame Dec. 18, 1934 2,162,844 Jenson June 20, 1939 2,181,407 Miller Nov. 28, 1939 2,200,861 Peoples May 14, 1940 2,207,553 Reeves July 9, 1940 2,230,276 Valjean Feb, 4, 1941 2,241,470 Miller May 13, 1941 2,260,839 Miller et a1. Oct. 28, 1941 2,261,814 Suchland NOV. 4, 1941 FOREIGN PATENTS Number Country Date 828,121 France Feb. '7, 1938

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