US2448148A - Pilot structure for pot type burners - Google Patents

Description

Aug. 31, 1948. J, w. MILLER EI'AL 2,443,148

PILOT STRUCTURE FOR POT TYPE BURNERS Filed Sept. 24. 1942 ZSheets-Sheet 1 O O O O .0 30

OO O O o O 0 O 0 O OO/IS o o o o a Q o o 0 o l O O O O 0 O O D G 0 0 23 34 24 FIG.2 v 26 'JOHN XI MIL'E'E' OR BY WALDO asmm Y 948. J. w. MILLER ETAL 2,448,148

I PILOT STRUCTURE FOR POT TYPE BURNERS Filed Sept. 24, '1942 2 Sheets-She et 2 Patented Aug. 31, 1948 PILOT STRUCTURE FOR POT TYPE BURNERS John W. Miller and Waldo G. Smith, Lansing, Mich., asslgnors to Motor Wheel Corporation, Lansing, -Mich., a corporation of Michigan Application September 24, 1942, Serial No. 459,500

21. Claims.

This invention relates to burners of the vaporizing pot type and constitutes an improvement in such burners.

This application is a continuation in part of our prior co-pending application Serial No. 410,- 498, filed September 12, 1941, now abandoned.

Burners of the vaporizing pot type are those burners which comprise a pot having a plurality of uniformly spaced apart air inlet openings in the side walls and in which the heat output can be-varied according to the demand on the heating system merely by varying the rate at which the fuel is supplied to the burner.

The principal problem met with in burners of the vaporizing pot type lies in producing a clean and stable fire at all stages of operation, that is, low fire, high fire or various intermediate stages.

To produce such a clean and stable fire the burner must be designed so that edd currents are substantially eliminated at all of the stages of operation of the burner without interfering with 'what is called pilot fire because eddy currents do form below the partition and either cause a smoky sooty flame or at times completely extinguish the flame. nates this condition, permitting a very low turn down of the fuel supply with a resulting clean and stable fire without in an way interfering with the normal operation of the burner at the higher stages of operation.

This result is accomplished by partially enclosing a portion of the burner adjacent the fuel inlet and below the partition. The enclosure is formed by the burner side wall, the bottom wall. a pair of upright non-intersecting baiiies positioned on opposite sides of the fuel inlet opening and certain of the air inlet openings, and an upper baffle which, in the cases where a partition is employed, is that partition. For best results the volume of the portion of the burner included in the enclosure should be about 3% to 5% of the total volume of the burner, and in any event, less than 10% of the volume of the burner. 'Also, the ratio between the totalarea of the air inlet open- The present invention elimiings directly communicating with the enclosure and the total area of all of the air inlet openings to the burner should be slightly greater than the ratio between the volume of the enclosure and the total volume of the burner. In other words, slightl more air per unit of volume should be admitted directly to the enclosure than to the burner.

With such an arrangement, the formation and circulation of eddy currents in the zone around the inlet openings are thus effectively prevented and the fire burns evenly and cleanly at the fuel flow of 25% to 40% less than that required to maintain a clean and stable fire without the invention. A substantial saving in fuel when little or no heat is desired is thus effected.

Referring now to the drawings:

Figure 1 is a cross-sectional view of a embodying the invention;

Figure 2 is a cross-sectional view on an enlarged scale of the burner shown in Figure 1;

Figure 3 is a cross-sectional view taken on substantially the line 3-3 of Figure 2;

Figure 4 is a cross-sectional view of a burner embodying a slightly modified form of the invention;

Figure 5 is a cross-sectional view taken on substantially the line 55 of Figure.4: and

Figure 6 is a plan'view of the baffle which forms a part of the enclosure about the fuel inlet opening.

heater The invention is shown in Figures 1 to 3 as embodied in a radiant heater comprising a casing having a combustion chamber ill and an air jacket Ii. The combustion chamber is provided with an access door I2 and has a flue outlet II. The casing is supportedon legs I4. end of the casing is open to admit air to the air Jacket ll.

A burner I5 is inountedin the air Jacket H. The side wall of the burner is held in place within the air jacket andtightly against the casing by means or a screw it threaded through the legs The burner i5 comprises a sheet metal side wall I! in substantially cylindrical form. Adjacent the upper edge of the side wall are two beads, an inwardly extending bead l8, and aboveit an outwardly projecting bead iii. A horizontal row of uniforml spaced apart secondary air inlet openings 20 is formed in the bead is so that the openings 20 are inclined upwardly and inwardly. Between the bead i8 and the lower edge of the side wall i! .are six substantially evenly spaced horizontal rows of substantially uniformly spaced The lower apart primary air inlet openings ii. In one side of the side wall, just above the lowermost row of primary air inlet openings II, is a concavity 22. the purpose of which will appear presently.

A cup shaped bottom wall portion 23 is welded to the bottom edge of the side wall II. The bottom wall is slightly concave. A fuelinlet opening 24 is provided at the side of the cup shaped bottom wall and is located directly below the concavity 22.

A fuel supply pipe 24 (see Figure 1) having a metering valve 25a therein is threaded into the opening 24. Directly below the opening 24 is a well 26 to retain fuel at periods of extreme low or pilot fire.

A centrally apertured top wall 21 rests upon the bead is. An anti-explosion baille it is seated upon the top wall 21 to direct a portion of the secondary air entering the air inlet openings II toward the aperture in the top wall.

Lying wholly between the lowermost and the uppermost rows of primary air inlet openings II is a partition 28 which divides the burner into a lower chamber 3i and an upper chamber-'12. The partition has a large central opening it to permit air, vapors and products of combustion to pass from the lower chamber to the upper chamber. The partition preferably is inclined as shown. Its lower edge is provided with a projection II which fits into the concavity 31 to position the partition in the burner, and is thereby located just above the lowermost row of air inlet openings. The upper edge of the partition rests against the side wall at about the level of -th fifth row of openings.

Below the partition and extending downwardly toward the bottom wall are two upright bames 34. The babies 14 are imperforate. Preferably .they are integral with the partition. The bailies 34 are located on opposite sides of the fuel inlet opening 24 and are spaced apart sufficiently to include some primary air inlet openings ll betweenthem. The outer and bottom edges of the bailles 34 are juxtaposed to the side wall I! and bottom wall 23 of the burner. Together with the partition 20, side wall II, and bottom wall 23 they provide a partial enclosure for the portion ofthe burner adjacent the fuel inlet. The enclosure is open at its radially inner vertical side.

Preferably .the baiiles 84 are arranged radially of the burner to eliminate any possibility of air entering the adjacent openings 2i impinging on them and causing a smoky flame.

Preferably the Danes 34 are arranged at an angle to each other of approximately 80 to 85 degrees. With the partition 2! inclined as shown, the volume of the. enclosure formed by the partition, the bai'lles I4 and the side and bottom'walls of the burner will be about 3% to 5% of the total volume of the burner.

Only certain holes'of the lowermost row of air inlet openingsnvill directly communicat with the enclosure. Ifthe baiiies 84 are arranged as indivcated above, there will be six of these openings and their area should be approximately 5% to 6% of the total area of the air inlet openin s in'the burner side wall. Thus. it will be' seen that the percentage of the area of the air inlet openings communicating directly with the enclosure is slightly greater than the percentage of the volume of the enclosure itself. This will assure adequate air for combustion at pilot fire.

In operating the burner, the metering valve is opened sufficiently to permitfuel to flow into the burner where it collects in the bottom of the burner. The fuel is ignited in any suitable way such as by inserting a lighted taper through the access door it. For a short time combustion will occur directly on the surface of the pool of fuel until suflicient heat is generated to vaporize a portion of the fuel. These vapors mix with the air entering the air inlet openings II from the air Jacket ii and the flame will move away from the surface of the pool of fuel in the bottom of the burner.

The rate of combustion can be varied by adlusting the metering valve to regulate the flow of fuel. In doing that th zone in which combustion is initiated can be varied. Thus, combustion may, in a general way, be initiated within the enclosure (low fire), outside oi the enclosure but within the lower chamber 3| (low intermediate fire), within the upper chamber 32 (high intermediate fire) or at the opening in the top wall 21 (high flre). The latter is the upper limit of combustion initiation.

While for the sake of convenience in description the burner has been divided into the four zones Just mentioned, it will be understood that there is no sharpline of demarcation between these zones. The combustion can be more closely regulated than that. It will also be understood that at low fire, combustion is not necessarily restricted to that part of the burner immediately on or over the well 26. The fire may spread out more into the enclosur about the fuel inlet opening.

As previously stated, the present invention has to do with improving the operation of the burner at low fire. In the devices ofthe prior art when operating at a low flre such, for example, as an oil flow of 300 c. c. per hour or less in a typical burner, the flame moves from one part of the burner to another and is extremely unstable. As th flow of oil is decreased from approximately 300 c. e. per hour the combustion reaches a critical point where when the flre moves from one part of the burner to another it may become extinguished. Moreover, throughout this low fire range of operation. because of the instability of the flame, there is an improper mixing of air with the oil vapors so that a smoky flame is produced.

Figures 4 to 6 disclose a somewhat modified form of the invention. The burner itself is substantially the same as that previously disclosed. It comprises a bottom wall ll having a fuel inlet opening ll formed in the side thereof adjacent the bottom. A tubular side wall it is welded to the upper edge of the bottom wall ll. The side wall is provided with six horizontal rows of air inlet openings I.

Near the upp r edge of the bln'ner' side wall are two rows of secondary air inlet openings 4, the same as in the previously described burner.

A top wall 5! and. an anti-explosion bailie it identical with those previously described are mounted in the burner adjacent the secondary air inlet openings and above the uppermost primary air inlet openings.

, A centrally apertured partition 51 is mounted in the burner. The partition is an annulus having an aperture II at its center. It will be noted that the portion of the partition located above the fuel inlet opening ii is inclined upwardly in exactly the same manner as the partition 2!, but the upper part of the partition is arranged horizontally intermediate the third and fourth row of air inlet openings from the bottom. The

partition I1 is the same as that disclosed in the oo-pending application of John W. Miller and Raymond E. Fell, Serial No. 407,850, flied August 22, 1941, and issued November 9, 1943, as Patent Number 2,334,117. ,This partition operates somewhat better than the wholly inclined partition of Figures 1 to 3. In and of itself it is not a part of this invention.

Instead of making the upright bafiies integral with the partition, as in the case of Figures 1 to 8, a separate baffle construction is employed in the device of Figures 4 to 6. This bailie' is shown in its entirety in Figure 6. It is a one piece inverted channel shaped construction having a web I. inclined upwardly at the same inclination as that of the inclined part of partition 51, and a pair of vertical legs or fi-anges 10. These legs are arranged so that their lower edges rest upon tition or may be welded or otherwise attached thereto.

The legs of the channel are arranged radially of the burner and at an angle to each other of approximateley 80 to 85 degrees, as in the case of the baiiies 34. Thus, the percentage of the volume of the enclosure formed by the bottom wall and side wall of the burner and the upright from the burner side wall.

legs II is approximately 3% to 5% of the total volume of the burner, exactly as in the case of the previously described modification.

The operationof the ,device shown in Figures 4 to 8 is identical to that shown in Figures 1 to 3.

At the low fire stage ofoperation of the burner described above the baffles of the present invention effectively prevent the circulation of eddy currents in the zone around the fuel inlet opening and thereby permit combustion to occur at low fire without the formation of soot. M the same time the bafile construction prevents extinguishment of the flame when at very low fire by preventing drafts 'due to such eddy currents. On the other hand, the baffle construction does not prevent spreading out of the fuel across the bottom of the burner at greater rates of fuel flow and does not in any way interfere with the effective vaporization of the fuel or the mixing therewith of the air for combustion.

From-a practical standpoint at any stage of the operation of the burner above pilot fire the baille construction is virtually non-existent. fact, at low fire the small portion of the burner within the enclosure acts as a tiny vaporizing pot type burner with a resultant clean and stable fire therein, and yet becomes an integral portion of the much larger burner when the burner is operating at the higher stages. of combustion.

The structure is exceedingly simple and economical to manufacture and install. Furthermore, the modification shown in Figures 4 to 8 can be installed in existing burners having partitions or in burners having no partition at all, with a consequent increase in efficiency there-- ture in the partition.

of spaced apart air inlet openings therein and a fuel inlet opening in the burner adiacent one side thereof, means cooperating with said 'bottom and side walls for partially enclosing a per 'tion of the interior of the burner adjacent said fuel inlet opening, said means comprising a pair of spaced apart non-intersecting upright baffles positioned on opposite sides of said fuel inlet opening and certain of said air inlet openings and a. third bailie engaging the upper ends of said pair of baiiles and lying wholly between the uppermost and lowermost air inlet openings, all of said bailles extending transversely of the burner, one upright edge of each bai'iie of said pair being juxtaposed to the burner side wall and the other upright edge beingspaced a substantial distance 2. A burner as defined in claim 1 wherein said third baille is a centrally apertured annulus having its peripheral edge in substantially ,continuous engagement with the burner side wall.

3. A burner as defined in claim 1 wherein said pair of baiiles engages the bottom wall of the burner.

4. A burner as defined in claim 1 wherein said third bai'ile is a centrally apertured annulus and said pair of bailles engage the bottom wall of said burner.

5. A burner as defined in claim 1 wherein said third 'baflle is a centrally apertured annulus and said pair of bafiies'extend radially of the burner from the side wall to the edge of the aperture in the annulus.

6. A burner as defined in claim 1 wherein said pair of baiiles are arranged radially of the burner.

7. A burner as defined in claim 1 wherein said pair of bailles are imperforate.

8. In a burner of the vaporizing pot type wherein combustion can be localized in different parts thereof by regulating the fuel supplied'thereto, said burner comprising a bottom wall. a tubular side wall having a plurality of spaced apart air inlet openings therein and a fuel inlet opening in the burner adjacent one side thereof, a centrally apertured partition extending across the burner and located wholly between the lowermost and uppermost air inlet openings, and a pair of spaced apart non-intersecting upright bailles on opposite sides of said fuel inlet and certain of said air inlet openings, said baiiies extending fromsaid side walls toward the aperture in the partition, said bailies being positioned between said partition and the bottom wall of the burner and cooperat ing with said bottom wall, side wall and partition to partially enclose a portion of the burner adjacent the fuel inlet opening, said enclosure being open at its radially inner and adjacent the aper- 9. A burner as defined in claim 8 wherein said balile's extend radially of the burner.

10. A burner as defined in claim 8 wherein said baii'lesmre integral with said partition.

11. A burner as defined in claim 8 wherein the baffles engage the partition, the bottom wall and the burner side wall.

12. A burner as defined in claim 8 wherein said bailles converge from the fuel inlet opening toward the center of the burner.

13. In a burner ofthe vaporizing pot typecomprising a bottom wall, a tubular side wall having a plurality of spaced apart air inlet openings therein and a fuel inlet opening in the burner adjacent one side thereof, and bafile means cooperating with the bottom wall and side wall of the burner'to partially enclose a portion of the latter adjacent the fuel inlet opening, said bame means comprising an inverted channel member having the legs thereof located on opposite sides of the fuel inlet opening and certain of said air inlet openings, one end of said channel member being juxtaposed to the burner side wall and the other end of said channel member being located adjacent the center of the burner.

14. In a burner of the vaporizing pot type comprising a bottom wall, a tubular side wall having a plurality of spaced apart air inlet openings therein and a fuel inlet opening in the burner adjacent one side thereof, a certainly apertured partition extending across the burner above said fuel inlet opening and located wholly between the uppermost and lowermost air inlet openings, and baiile means cooperating with the bottom wall and side wall of the burner to partially enclose a portion of the latter adjacent the fuel inlet opening, said baille means comprising an inverted channel member positioned beneath said partition, one end of said channel member being juxtaposed to the burner side wall with the legs of said channel positioned on opposite sides of said fuel inlet opening and certain of said air inlet openings and the other end of said channel member being, positioned adjacent the opening in the partition, the web of the channel member engaging the under side of the partition and above said fuel inlet opening, and a pair of lugs integral with the partition engaging the channel member to hold the same in position relative to the burner.

15. As an article of manufacture, a low fire pilot for use in combination with an oil burning vaporizing pot type burner of the type comprising a chamber having a bottom wall, generally upright side walls perforated to admit air to support combustion and an oil admission opening for delivering oil onto the bottom wall of the chamber; said pilot comprising structure including a top'wall and downwardly extending side walls forming an inverted channel open at opposite ends, said side walls of the pilotvstructure being adapted to rest uponthe bottom wall of the pot and in a position to cover the oil delivered, for pilot purpose, to the bottom wall of the pot, said structure being positioned so that one open end of the channel registers with certain of the perforations in the side walls of thepot and the upright ends of the side walls of last mentioned end of structure are juxtaposed with the upright side walls of the pot, certain of the walls of the pilot structure converging toward one another from the last mentioned end of the pilot structure toward the other open end thereof.

mission of the fuel to the pot and defining a space in communication with a plurality of the lower primary air inlet apertures of the pot, said.

housing including generally upright inwardly converging side walls defining a flame outlet at their convergence, and extending inwardly from the pot wall, and means for delivering liquid fuel to the pot at a point enclosed by said pilot housing.

8 17. in combination, an open topped burner pot having a circumferential wall provided with a plurality of primary air inlet apertures located at various levels in the wall, means for delivering secondary air to the mixture ofprimary air and vaporized fuel moving upwardly through the pot and a pilot housing surrounding the area of admission of the fuel to the pot and defining a space in communication with a. plurality of the lower primary air inlet apertures of the pot, said housing including generally upright inwardly converging side walls defining a flame outlet at their convergence, and extending inwardly from the circumferential ot wall, and cover means for said housing, said cover means located below the level of the highest of the primary air inlet apertures and below the level of admission of secondary air to the mixture, and means for delivering liquid fuel to the pot at a point enclosed by said pilot housing.

18. In combination, an open topped burner pot having a circumferential wall provided with a plurality of primary airinlet apertures located at various levels in the wall, means for delivering secondary air to the mixture of primary air and vaporized fuel moving upwardly through the pot and a pilot housing surrounding the area of admission of the fuel to the pot and defining a space in communication with a plurality of, the lower primary air inlet apertures of the pot, said housing having generally upright, converging side walls and a top wall, the top wall being located below the level of the highest of the primary air inlet apertures and below the level of admission of secondary air to the mixture, the inner edges of said side and top walls defining a flame aperture in communication with the interior of the pot, and means for delivering liquid fuel to the pot at a point enclosed by said pilot housing.

19. A liquid fuel burner comprising. in combination, a combustion pot having generally upri ht side walls and a connecting bottom wall, said side walls having upper and lower perforations, said pot being open at the top; means forming a substantially horizontally extending fuel vaporizingchamber 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 communicating with certain of said lower perforations, said chamber having a fuel mixture outlet confronting a side wall of the pot opposite said first mentioned side wall; means for supplying liquid fuel to the chamber; and gas and air baflie 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.

20. In combination, an open topped burner pot having a circumferential wall provided with a' plurality of primary air inlet apertures located at various levels in the wall, means for delivering secondary air to the mixture of primary air and vaporized fuel formed in the pot and a pilot housing surrounding the area of admission of the fuel to the pot and defining a space in communication with a plurality of the lower primary air inlet apertures of the pot, said housing including upwardly extending side walls and a top wall and having, adjacent the inner ends of said side and top walls, a flame outlet of substantially smaller area than the area of the pot wall which is in register with the interior of the pilot housing, the highest part of said pilot housing being located below the level of the highest of said primary air inlet apertures, and means for delivering liquid fuel to the pot at a point enclosed by said pilot housing.

21. In combination, an open topped burner not having a circumferential wall provided with a plurality of primary air inlet apertures located at various levels in the wall, means for delivering secondary air to the mixture of primary air and vaporized fuel formed in the pot, and a pilot housing surrounding the area of admission of the fuel to the pot and defining a space in communication with a plurality of the lower primary air inlet apertures of the pot, said housing including generaily upright side walls and having a flame outlet at the inner ends of said side walls, said side walls extending inwardly from the pot wall, and means for delivering liquid fuel to the pot at a point enclosed by said pilot housing.

- JOHN W. MILLER. WALDO 6. SMITH.

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

UNITED STATES PATENTS

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