US3402985A

US3402985A - Burner recirculating chamber construction

Info

Publication number: US3402985A
Application number: US530233A
Authority: US
Inventors: Ralph B Galvin
Original assignee: Stewart Warner Corp
Current assignee: Stewart Warner Corp
Priority date: 1966-02-25
Filing date: 1966-02-25
Publication date: 1968-09-24
Anticipated expiration: 1985-09-24

Description

Sept. 24, 1968 R. B. GALVIN BURNER RECIRCULTING CHAMBER CONSTRUCTION 3 Sheets-Sheet-l Filed Feb. 25, 1966 Sept. 24, 1968 R. B. GALVIN BURNER RECIRCULATING CHAMBER CONSTRUCTION Filed Feb, 25. 1966 3 vSheets-Sheet 2 Sept. 24, 1968 BURNER RECIRCULATING CHAMBER CONSTRUCTION :5 sheets-sheet Filed Feb. Q5, 196e United States PatentO 3,402,985 BURNER RECIRCULATING CHAMBER CONSTRUCTION Ralph B. Galvin, Indianapolis, Ind., assignor to Stewart- Warner Corporation, Chicago, Ill., a corporation of Virginia Filed Feb. 2S, 1966, Ser. No. 530,233 3 Claims. (Cl. 431-116) ABSTRACT OF THE DISCLOSURE A recirculating chamber for a vaporizing combustion type heater utilizing a scroll-shaped nozzle for driving combustion air in an arcuate lpath past a portion of an opening formed in a wall through which vaporized fuel exits. An arcuate baille projecting from the wall having an edge terminating in the air stream and circumscribing another portion of the opening in a direction transverse to the air path for dividing the air into a main stream and a recirculated part. The recirculated part thereby vbeing caused to move past the other opening portion for entrainment of fuel in the air stream. A target baffle at the end of the arcuate baffle and perpendicular thereto confining and controlling both the recirculating air and the main stream.

The present invention relates in general to burners for use in small capacity diesel fuel consumption heaters and more particularly to a burner construction providing reduced coking and smoke together with greater flame stability.

Aircraft and vehicle heaters employ surface vaporizing type burners in which a liquid fuel is vaporized from a wick by an igniter for combustion and combustion is maintained 'by forced draft combustion air. The forced draft combustion air is driven at high velocity past a recirculating vaporizing chamber in which the vaporized fuel is burned. In this arrangement the problems of coking, smoking and flame stability are aggravated due to variations in air/fuel ratio and heat release when heavier grades of distillate fuels containing high carbon contents, commonly known as DF 1, DFZ or DFA, are burned.

It is therefore one object of the present invention to provide an improved recirculating vaporizing chamber for use in a vaporizing combustion type heater to reduce coking and smoke and improve llame stability when fuels of the above mentioned type are burned.

Other objects and features of this invention will become apparent on examination of the following specilication and claims together with the drawings, wherein:

FIG. 1 is a longitudinal sectional view of a burner and heat exchanger assembly taken generally along the line 1 1 in FIG. 2 and incorporating the principles of the present invention;

FIG. 2 is a sectional view of the assembly taken generally along the line 2 2v in FIG. l;

FIG. 3 is a rear View of the burner assembly plate;

FIG. 4 is a perspective view of the burner assembly;

FIG. 5 is a perspective View of the fuel inlet and ignition portion of the burner assembly; and,

FIG. 6 is a perspective view of another burner assembly incorporating the .principles of the present invention with portions of the assembly partially broken away.

In FIG. 1 a 'burner assembly and a portion of a heat exchanger assembly are generally indicated by the reference characters 19 and 12, respectively. The burner assembly 10 and particularly the assembly 12 are generally similar to that shown and described in U.S. Patent No.

The heat exchanger assembly 12 is dened by an outer 3,402,985 Patented Sept. 24, 1968 ice circumferential wall 14 having inwardly deformed portions at opposite ends joining a second wall 16. The wall 16 is generally annular but has inwardly folded radial wall sections 18 along a portion of its lperiphery. Sections 18 are joined to a second interrupted annular wall 20 spaced inwardly of wall 16. The space between the two walls 16 and 20 is provided with a series of heat exchanger ns 22 which aid in transferring heat to incoming air entering the space between walls 16 and 20 at one end thereof and exiting at the other end thereof as explained in said patent. The space between sections 18 and the interruption in wall 20 define a passageway 24 communicating exhaust burner gases from the burner assembly 10 and ay chamber 26 defined by wall 20 to the space between walls 14 and 16 for exit through an outlet conduit or stack 27. The chamber 26 is closed at one end by a wall, not shown, and the burner assembly 10 is located at the opposite end of chamber 26.

The burner assembly 10r comprises a circular burner .plate 28 with a peripheral ange 30 seated against the end of wall 20 to close the end o-f the chamber 26. A hollow boss 32 is provided on the rear of plate 28 below the horizontal axis' and adjacent the vertical axis of the plate to provide a fuel vaporizing chamber 34. Metered fuel is supplied to the chamber 34 from an inlet pipe 36 through an opening in the upper wall of boss 32. A vertical partition '38 in chamber 34 divides the chamber and an opening 40, best seen in FIG. 5, in partition 38 receives a wick portion 42 for conducting fuel from the pipe 36 through opening 40. The wick portion 42 is supported on a horizontal platform 44 and additional wick material 46 is disposed below the platform 44.

A glow type igniter (not shown) is provided in the chamber 34 through a second opening 48 in the top wall of the boss 32 and leads for the igniter extend through a conduit 50. The igniter comprises an electrical element for vaporizing the fuel supplied to the wick 42 until the fuel is heated to its combustion temperature. Once the fuel is ignited, combustion is self-sustaining and a flame detector switch (not shown), controlled by a sensing element (not shown) in chamber 26, for exam-ple, serves to deenergize the igniter in any well known manner. The heated vaporized fuel in chamber 34 exits through an opening 52 extending through plate 28.

Combustion air is supplied to assembly 10 by a blower indicated at 54 from a chamber S6 to the rear of plate 28, as seen in FIG. 1. The combustion air is extended both through an opening 58 just above the center of plate 28 to provide secondary combustion air and through an arcuately extending opening 6G in plate 28.

The central opening 58 communicates with a passageway 62 defined by an annular wall 64 projecting from the front of plate 28, with the annular wall terminating in a nose cone 66 having a series of perforations 68 for introducing the secondary combustion air into the burning Vaporized fuel.

The arcuate opening 60 is disposed radially from opening 58 and is initiated adjacent the horizontal axis of plate 30 and extends in a counterclockwise direction, as seen in FIG. 3, to a position beyond the vertical axis of plate 30. Opening 60 communicates with a circumferential or arcuate passageway 70. An inner wall is formed for passageway 70 by a portion of wall 64 from adjacent the lower edge of opening 60 for approximately 180. A wall 72, extending spirally or tangentially outward of wall 64, as best seen in FIG. 4 from adjacent the end of opening 60 toward the outer edge of plate 28, thereafter forms the inner wall of passageway 70.

A wall 74, spaced from wall 64, forms the outer wall of passageway 70 to maintain the air in passageway 70 in an arcuate or spiral flow path. Wall 74 (see FIG. 4) is initiated from a position adjacent the nozzle end of wall 72 and extends in a somewhat arcuate shape tangent p to the wall 64 in a radial direction from right to left as seen in FIG. 4 to form a back or closed end for passageway 70, and then wall 72 extends in a circumferential direction and terminates spaced from the end of wall 72 and below wall 80 to form a step nozzle 76 for passageway 70 below wall 80 and above plate 28. The space, triangular in cross section, between

walls

72, 74 and 64 serves as insulation space. An insulating and rigidifying baille wall 78 (FIG. 1) has its ends joined to wall 74 adjacent the initiation of opening `60 and adjacent the Vend of opening 60, and is spaced therefrom intermediate those positions. j Y

The wall 80, spaced from plate 2S by a distance corresponding to the axial length of wall 64, serves to confine the air in passageway 70 until it exits from between walls 72 and 74 at opening 76 in a generally spiral path. In addition, a ramp plate 82, extending between walls 72 and 74 from opening 76 at an incline to plate 28, provides improved control of the air stream exiting from the air byfbaille 92, wall 74, and, the-tangential air stream issuing nozzle 76. The nozzle '7.6 is a step nozzle with the end of wall 74 extending slightly beyond the end of wall 72 to direct a high velocity air stream tangentially past opening 52.

The air stream thus moves in a generally outward spiral path from opening 76 past a recirculating chamber 84 adjacent opening 52 and partially defined by a target baille 86 parallel to plate 28 and a generally conical baille 88 extending from adjacent the periphery of plate 28 into chamber 26.l Target baille 86 extends from adjacent step nozzle 76 for approximately 180. A crossover baille 90 is atached to baille 88 and burning fuel moves in chamber 26 until it passes the end of baille 90, whereafter it exits through passage 24. The opening at the end of baille 88 adjacent chamber 26 is also partially closed by a bafile plate 91, which serves to cover about 180 of the opening in baille 88 at a position calculated to enhance spiral ilow.

To aid in overcoming the deleterious situations previously described, an arcuate baille plate 92, projecting from plate 28 into abutment with target baille 86, is provided adjacent opening 52. Batlle plate 92 is initiated adjacent the portion of wall 74 tangent to wall `64 and generally follows the periphery of opening 52 for a distance of approximately 90 in a direction counter that of the air stream exiting from nozzle 76 to form a concave wall facing the stream. The plate 92 is then formed with a lip 94 projecting somewhat over more than half the lower portion of the opening 52. The lip 94 is given a slight upward tilt in .a direction away from plate 28 and defines an opening between it and baille 88 for passage of the air stream tangentially past chamber 84. A support plate 96 is connected between the circumferential portion of wall 74 and plate 92.

The air stream exiting from opening 76 ilows generally tangentially past opening 52 with baille 92 diverting a portion of the stream into a recirculating ilow in charnber 84. The recirculating flow then moves in tangential relationship with the air stream from nozzle 76 and a portion is entrained therein. Combustion occurs between bailles 88 and 92 in the high velocity air stream to provide the main ilow and extending about wall 74 and exiting over the top of target baille 86 and thence through the opening in baiile 88. A small llame swirls about in chamber 84 due to the entrainment of suilcient low velocity air to maintain a pilot flame, and as the fuel vaporizes in chamber 84 it is pulled or entrained into the high velocity air stream in non-turbulent streamlined ilow. The mixture swirling in chamber 84 also contains inert gases such as CO2, H2O and N2 which act as a butler to aid in preventing coking and smoke chains while the high rate of vaporization from the wick maintains it cool. The recirculation prevents a fuel vapor barrier from forming at the vicinity of opening 52 and instead disperses the vapor. Thus, the recirculation chamber 84 is generally defined from nozzle 76.

In FIG. 6 another type of burner assembly is illustrated using the principles of the present invention. A burner plate 98 having a wire mesh or wick retainer 100 holds a wick material in engagement with one face of the plate. An opening 102 permits vaporized fuel from an igniter chamber to pass into a recirculating chamber 104 defined by a housing 106. The housing 106 is formed by a circular wall 10S-having an integrally formed end wall 110 spaced from the plate 98. The walls .108 and 110 are truncated along a line transverse to the plate axes and extending across va corner-fofopening 102. The housing 106 serves so as to entrain a portion of a main .air stream exiting in a tangential direction through an opening in a conical baille 112 from a conduit 114. A target baille 116 spaced about 1A from wall 110 directs the main air stream into a spiral ilow.

The main ilow circulates about the exterior of wall 108 and exits through the opening in the conical `baille while a portion of the air stream is entrained by housing 106 and then reenters the main air stream due to the tangential boundary in non-turbulent streamlined ilow.

The foregoing description is directed to an improved burner for use with heavier grade fuels with the inventive concepts of said burner believed set forth in the accompanyng claims.

What is claimed is:

1. A vaporizing burner of the type including means for vaporizing fuel in a chamber having a wall in which an opening is formed through which vaporized fuel exits, the improvement comprising means for driving combustion air in an arcuate path axially confined on one side by said wall and directed past a iirst portion of said opening, a baille projecting perpendicularly from said wall in an arcuate path initiated adjacent an inner radial point of said air path and extending about another portion of said opening into said first portion in a curve transverse to the direction in which said air stream is driven and terminating in said` air stream at a position generally parallel to said air stream for separating said stream into two parts with one of said parts directed by said arcuate baille towards said radial point for subsequent entrainment in said stream and the other part constituting the main air stream, a conical baille encircling said main air stream, arcuate baille' 'and' said opening for radially confining said main air stream, and a planar target baille opposite said opening and located adjacent the projectingy end of said arcuate baillewith said target baille meeting the inner surface of said conical baille for a predetermined arc to axially conilne both parts of said air stream between said wall and conical baille for an angular distance corresponding to said predetermined arc to complete a rccirculating chamber for said one part of said air stream while providing an exit for said main air stream between said conicalv baille and said target baille.

2. A vaporizing burner of the type including an igniter extending into a chamber having a wick carrying fuel with said chamber having a wall with an opening therein through which said vaporized fuel exits, the improvement comprising means for driving combustion air axially confined on one side bysaidV wall past a portion of said opening in a spiral path having an axis parallel'to the axis of said opening and directed past a first portion of s'aid opening, a bafile projecting -perpendicularly'from said wall in an arcuatel pathiriitiated adjacent an inner radial point of said air path and extending about another portion of the periphery of said opening and following the periphery of said opening into said first portion in a direction transverse to the direction in which 'said lair stream is driven andterminating in said "air stream at a position generally parallel to `said air stream for intercepting a portion of said combustion air to form a mixture of said intercepted air and vaporized fuel adjacent said opening to be entrained in said driven combustion air with the unintercepted portion of said air stream constituting the main air stream, and a semicircular target bafe spaced adjacent the end of said baie plate and opposite said opening for axially confining both said intercepted and main air streams.

3. A vaporizing burner of the type including an igniter extending into a chamber having a wick carrying a diesel fuel with said chamber having a wall with an opening therein through which said vaporized fuel exits, the improvement comprising a step nozzle through which cornbustion air axially confined on one side by said wall is driven in a spiral path about an axis parallel to the axis of said opening and adjacent a rst portion of the periphery of said opening, a bafle spaced from and encircling said opening, nozzle and combustion air for radially confining said path, an arcuate baie projecting in a direction parallel to said axes and extending from adjacent said step nozzle about another portion of the periphery of said opening with said arcuate batlie thereafter following the periphery of said opening in a direction transverse to said spiral path and terminating in and generally paral- References Cited UNITED STATES PATENTS 77,124 4/1868 Suhr 158-4 1,660,106 2/1928 Stroud 158-91 2,208,851 7/1940 Mcllvaine et al. 158-91 2,507,081 5/1950 Allen et al. 158-28 X 2,663,366 12/1953 Harris 158-91 X 2,850,004 9/1958 Fairbanks 126-116 FREDERICK KETTERER, Primary Examiner.