US3014523A

US3014523A - Fluid fuel burner

Info

Publication number: US3014523A
Application number: US578771A
Authority: US
Inventors: Ernest C Huge
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1956-04-17
Filing date: 1956-04-17
Publication date: 1961-12-26
Anticipated expiration: 1978-12-26

Description

Dec. 26, 1961 E. (3. HUGE FLUID FUEL BURNER Filed April 17, 1956 INVENTOR. Ernesr C. Huge ATTORNEY Patented Dec. 26, 1961 3,914,523 FLUTE FUEL BURNER Ernest ll. Huge, Akron, tlhio, assiguor to The Bahcoch Wilcox Company, New York, N.Y., a corporation of New Hersey Filed Apr. 17, 1956, der. No. 578,771 Claims. (Cl. 153-1.5)

The present invention relates to fuel burners, and more particularly to fuel burners for producing long narrow flames in furnaces.

Heretofore, oil and gas burners have been constructed and arranged for the production of a short bushy flame where combustion is completed in a minimum distance from the tip of the burner. The usual liquid or gaseous fuel burner has been constructed to attain an intimate mixing of the fuel and air with the mixture discharged from the burner as a swirling, expanding mass of flame into a furnace. Intimate mixing of the fuel constitutes is necessary and desirable for complete combustion. Lengthing the flame has been attempted by increasing the velocity of the mixture discharged from the burner, and sometimes by delaying the mixing of air and fuel so as to obtain delayed combustion. Neither delaying combustion nor increasing the velocity of the streams of fuel and air entering the furnace have been at all satisfactory due to instability of combustion particularly during changes in the rate of fuel discharged through the burner, and/or by incomplete combustion of the fuel.

In accordance with the present invention, I provide a fluid fuel burner which is capable of producing a long flame which is stable over a wide operating range and attains substantially complete combustion of the fuel. This is accomplished by a novel arrangement of a frustoconical air chamber having its base positioned adjacent the port opening in a furnace wall and arranged for the introduction of combustion air to the air chamber in directions having tangential and longitudinal components of motion with respect to the axis or the air chamber. The fuel, whether liquid or gaseous or both, is introduced into the air chamber for discharge with the combustion air through the base of the frusto-conical air chamber and the associated throat. Cooperating with the frustoconical air chamber is a port construction in the wall of the furnace which is characterized by an outwardly diverging frusto-conical portion ending and merging with an inwardly converging frusto-conical portion which forms the discharge end of the throat formed in the wall port.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of the invention.

Of the drawings:

PEG. 1 is an elevation, partly in section, of a burner assembly constructed in accordance with the present invention;

FIG. 2 is an end view on line 2-2 of FIG. 1; and

FIG. 3 is an enlarged section of a portion of the apparatus shown in FIG. 1.

in the illustrated embodiment of the invention shown in the drawings, the burner assembly is shown as adapted for either liquid or gaseous fluid. The invention is shown as applied to a furnace having a refractory wall wherein the burner port is provided with a refractory throat of special configuration. The burner may be positioned for discharge in a horizontal direction or it may be positioned for vertical discharge into a furnace.

Referring to FIG. 1, the air chamber or register 10 of the burner is constructed with a frusto-conical wall 11 having its base 12 attached to the exterior side of the wall 13 of a furnace 14. In the embodiment shown, the base angle of the frusto-conical wall is of the order of 10, and outwardly of the wall a cylindrical extension 15 is provided with a diameter equal to the smaller diameter of the frusto-conical wall 11 and coaxial therewith.

As shown, the frusto-conical air register 10 is provided with three circumferentially equally spaced air inlet ports 16. Each of the ports is provided with an air inlet housing 17 of substantially uniform rectangular cross section where a plane equally spaced between and parallel to the sides of each housing is tangent to an imaginary cone within the frusto-conical wall 11. Each of the air inlet housings i7 is inclined away from the base 12 of the frusto-conical wall. As shown particularly in FIG. 2, the air inlet housings 1'7 are inclined at an angle of approximately 45 with respect to the axis of the air register. Air may be delivered to an enclosure 19 under a superatmospheric pressure from an external source (not shown) and discharged through the housings 17 into the burner. Suitable damper control means are provided such as a plate damper 18 positioned on each housing 17 to regulate air how to the burner. The plate dampers 18 associated with each of the housings 17 is arranged for individual ad ustment, and optionally, for coordinated movement. Ordinarily, the plate dampers are operated in unison, but may be individually postioned to change the lateral position of the flame within the furnace 14-. With the housing construction described, the air entering the air register ill will discharge through the inlet ports 16 of the air chamber in a direction resulting in a swirling, expanding movement entering the furnace 14.

The air inlet housings 17 are preferably provided with vanes 20 which straighten the air stream entering the air inlet housings and generally distribute the air uniformly throughout the cross section of the inlet housings. The vanes are constructed of thin sheets of metal which are attached to the side Walls of the housings and are disposed in spaced planes parallel to the end walls of the air inlet housings 17.

As shown in PEG. 1, the fuel burner is provided with a liquid fuel atomizer 21 which is inserted through a tube 22 positioned in coaxial relationship with the axis of the cylindrical outer end portion 15 and the frusto-conical wall ll of the air chamber 10. The tube 22 is supported by the outer end wall 23 of thecylindrical portion l5 and by spaced arms 2 which are welded to both the tube and the cylindrical portion 15 of the airchamber. As shown in PEG. 2, there are three of these support arms with the opposite ends of each welded to the tube and the cylindrical outer wall adjacent the junction between the cylindrical and the frusto-conical portions of the as sembly.

The atomizer head 21 is assembled on the end of a supply tube 2.5 which has an outside diameter less than the inside diameter of the tube 22 and is extended through the tube 22 so that theatomizer head 21 projects beyond the base 12 of the frustoconical walls 11 into the burner port 26 formed in the furnace wall 13. The outer end of the supply tube 25 is provided with the usual valves and quick release fuel oil couplings (shown at 27) for attachment to a source of pressurized fuel oil. The atomizer illustrated is of the mechanical type similar to that disclosed in US. Patent 2,372,283. It Will be understood that other type of mechanical or steam operated atomizers may be utilized for the delivery of the fuel oil to the furnace. The atomizer assembly described can be removed from the tube 22 and the exterior end of the tube may be capped if desired. The removal of the oil U atomizer assembly is desirable to protect the assembly from heat damage when gaseous fuels are in use.

The burner assembly illustrated in the drawings is constructed and arranged for'the introduction of a gaseous fluid such as, for example, natural gas. This fuel is delivered to the air chamber adjacent the base 12 of the frusto-conical wall 11 air chamber assembly. The gaseous fuel is introduced through a plurality of removable gas delivery spuds 30 which are each constructed of a tube having one end thereof cut at an angle of with respect to the axis of the tube, to form the discharge end of the tube. The discharge end of each tube is provided with a plate 31 which is welded into position and drilled to form a multiplicity of small gas outlet openings 32. The openings are drilled at an angle of substantially 99 with respect to the axis of the gas inlet tube. Thus, the gas outlet openings are drilled at an angle of approximately 10 with respect to the face plane of the plate 31 in the discharge end of the gas tube.

The air inlet chamber it? is provided with three circumferentially equally spaced tubes 33 which are arranged with the axes of the tubes parallel to the axis of the frusto-conical and cylindrical portions of the air chamber 10. The discharge end of the tubes 33 are cut at an angle and welded to the wall 11 adjacent the base 12 of the air chamber. The wall of the inlet chamber is removed to provide a matching series of openings communicating between the tubes 33 and the interior of the air chamber 10. The tubes 33 are supported adjacent their outer ends by welding to spaced openings in the end plate 23.

In the illustrated embodiment of the invention, the gas inlet tubes 33 are three in number and are circumferentially equally spaced about the exterior of the cylindrical portion of the air chamber with the discharge end portions thereof closely spaced from the base of the frusto-conical portion of the air chamber. More or less gas inlet positions may be provided according to fuel needs. The gas inlet spuds 36 may be inserted through the support tubes 33 with the discharge end portions of the spuds positioned substantially flush with the wall of the frusto-conical wall 11 of the air chamber. The outer ends of the gas spuds are suitably connected to a source of gaseous fuel. When gaseous fuel is not required, the spuds may be removed and the outer end of the tubes 33 capped.

With the base portion of the frusto-conical inlet chamber 10 attached to the external surface of the furnace wall 13, the interior circumference of the refractory material 34 forming the burner port 26 has an interior diameter substantially equal to the base diameter of the air chamber. The refractory material is extended inwardly toward the furnace with a substantially uniform diameter for a short distance to form a cylindrical surface 35. Thereafter, the interior surface of the burner port is formed with an outwardly diverging frusto-conical inner surface 36 where the smaller diameter merges into the cylindrical surface 35 of the port. The base of the frusto-conical interior surface 36 of the burner port is joined to the base of a second frusto-conical interior surface 37 formed in the refractory port where the smaller diameter of the second frusto-conical surface 37 has a larger diameter than the cylindrical innersurface 35. The furnace end, smaller diameter, portion of the second frusto-conical surface 37, is provided with a generally rounded edge surface 38 and forms the furnace discharge end of the burner port. With the construction described the burner port is shaped to form a throat of refractory material where a cylindrical inner surface merges into an outwardly diverging surface and an inwardly converging discharge end portion.

The air chamber construction described is advantageously provided with a lighter port 4% which is positioned circumferentially adjacent one of the gas inlet openings. As shown in FIGS. 1 and 3, the lighter port 40 is of generally rectangular configuration and is provided with a metallic hooded member 41 on the exterior of the wall ill which is constructed to accommodate the insertion of an electrically ignited gas pilot. The igniter assembly (not shown) may be of the retractable type, such as described in U.S. Patent 2,692,642.

in one installation of fuel burners constructed and arranged as described, the burners were each rated at twenty million Btu. per burner per hour when burning fuel oil or natural gas. Combustion air delivered to the burner was preheated to a temperature of approximately 1000 F. For this capacity, the air chamber it} including both the frusto-conical and cylindrical wall portions 11 and 15, respectively, had an overall length of approximately 45 The cylindrical portion of the chamber had a diameter of 9 and the base 12 of the frusto-conical wall was approximately 19 /2" in diameter. The burner was provided with three air inlet housings 17, such as shown and described, and was also provided with three gas inlet spuds 30. The burner port construction included a cylindrical inner surface 35 approximately 5" in depth and a diameter corresponding to the base of the frusto-conical Wall portion of the air chamber. The outwardly diverging surface 36 of the throat had a base angle of 60 and a depth of approximately 9". The inwardly diverging frusto-conical surface 37 of the throat was approximately 5 in depth and had a discharge opening 38 of 25 In operation, each of the burners described produced a flame having an approximate length of over 20 feet with a maximum flame diameter of less than 4'. This flame characteristic was substantially the same for either fuel oil or gas and was characterized by an unusual high flame stability even when operated over a fuel input range of 5 to l. Combustion of the fuel was complete with low excess air and the burner operations was extremely satisfactory, even though the burner was positioned vertically for upward discharge into the furnace.

While the illustrated embodiment of the invention shows the air inlet housings arranged at a 45 degree angle with respect to the horizontal axis of the air register, it will be appreciated that the angle may be changed to vary the characteristics of the flame shape. An angle greater than 45 degrees would increase the length of the flame, and conversely, decreasing the angle would shorten the length of the flame.

While in accordance with the provisions of the statues I have illustrated and described herein the best form and mode of operation of the invention now known to me, those skilled in the art will understand that changes may be made in the process without departing from the spirit of the invention covered by my claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of other features.

The claims are:

1. A fuel burner comprising a hollow frusto-conical member having a length greater than its base diameter, means for introducing fuel into said burner at a position closely spaced from and adjacent to the base of said frusto-conical member, and means for introducing combustion air through the frusto-conical member and intermediate the axial length of said member with components of motion tangential to the wall of and toward the base of said member including a circumferentially spaced series of air inlet housings opening to the interior of said frustoconical member, said housings being inclined at an acute angle away from the base of and tilted with respect to the axis of said frusto-conical member to provide a tangential and axial component of air inlet motion entering said member and passing through the base of said member in contact with said fuel.

2. In combination with a furnace wall having a port therein, a frusto-conical air register member having its base attached to said furnace wall and registering with said port, a plurality of straight tubular elements spaced about and substantially parallel to the axis of said frusto' conical member and having one end of each opening to the interior of said member adjacent the base thereof, a gaseous fuel conduit inserted through each of said tubular elements with the discharge end of each substantiallyv flush with the inner surface of said frusto-conical member, and a plurality of air inlet ducts circumferentially spaced about said frusto-conical member and opening to the interior thereof, each of said ducts being inclined away from the base of and with respect to the axis of said member to discharge combustion air into said member with tangential and axial components of movement toward the base of said member and said furnace port.

3. In combination with a furnace wall having a port therein, a hollow frusto-conical air register member hav-- ing a length greater than its base diameter and with its base attached to said furnace wall and registering with said port, a tubular element coaxially extending through said frusto-conical member to a position closely spaced from and adjacent to the base of said member, a liquid fuel delivery pipe with an atomizing head thereon extending through said tubular element positioning said atomizing head beyond and closely spaced adjacent the base of said member, and a plurality of air inlet ducts circumferentially spaced about said frusto-conical member and opening to the interior thereof, each of said ducts being inclined at an acute angle way from the base of said member and tilted with respect to the axis of said member to discharge combustion air into said member with tangential and axial components of movement toward the base of said member.

4. In combination with a furnace wallhaving a port therein, a frusto-conical air register member having its base attached to said furnace wall and registering with said port, a tubular element coaxially extending through said frusto-conical member to a position spaced from the base of said member, a liquid fuel delivery pipe with an atomizing head thereon extending through said tubular element, a plurality of straight tubular elements radially spaced about and substantially parallel to the axis of said frusto-conical member and having one end of each opening to the interior of said member adjacent the base thereof, a gaseous fuel conduit inserted through each of said tubular elements with the discharge end of each substantially flush with the inner surface of said frustoconical member, and a plurality of air inlet ducts circumferentially spaced about said frusto-conical member and opening to the interior thereof, each of said ducts being inclined away from the base of and with respect to the axis of said member to discharge combustion air into said member with tangential and axial components of m en w d the ase f s d e er 5. In combination with a furnace wall having a port therein, a frusto-conical air register member having its base attached to said furnace wall and registering with said port, a refractory ring positioned within said port coaxial with the base of said frusto-conicai member, said ring having a cylindrical portion adjoining the base of said frusto-conical member and having substantially the same internal diameter as said base, an outwardly flaring frusto-conical ring portion merging into said cylindrical portion at one end thereof and merging into an inwardly tapering frusto-conical portion at the opposite end remote from said frusto-conicalmember and of greater diameter than said cylindrical portion, a tubular element coaxially extending through said frusto-conical member to a position inwardly spaced from the base of said member, a liquid fuel delivery pipe with an atomizing ihead thereon extending through said tubular element, a plurality of straight tubular elements radially spaced about and substantially parallel to the axis of said frustoconical member and having one end of each opening to the interior of said member adjacent the base thereof, a gaseous fuel conduit inserted through each of said tubular elements with the discharge end of each substantially flush with the inner surface of said frusto-conical member, a plurality of air inlet ducts circumferentially spaced about said frusto-conical member and opening to the interior thereof, each of said ducts being inclined away a from the base of and with respect to the axis of said member to discharge combustion air into said member with tangential and axial components of movement toward the base of said member, and means for igniting said fuel entering said ring.

References Cited in the file of this patent UNITED STATES PATENTS 1,429,090 ONeil Sept. 13, 1922 1,698,555 Molz Jan. 8, 1929 1,840,840 Goldsborough Jan. 2, 1932 1,865,983 Warner July 5, 1932 2,153,951 Barber Apr. 11, 1939 2,304,294 Wood Dec. 8, 1942 2,540,416 Asscher Feb. 6, 1951 2,552,492 Nathan May 8, 1951 2,572,338 Hartwig Oct. 23, 1951 2,579,614 Ray Dec. 25, 1951 2,806,517 Nuyl Sept. 17, 1957 FOREIGN PATENTS 500,933 Germany Feb. 12, 1928