US3469791A - Gas burner - Google Patents

Description

Sept. 30, 1969 w. H. DE LANCEY 3,469,791

GAS BURNER Filed Jan. 2, 1968 INVENTORS IVA/new H. Debra/cs7 BY H585! G Ha s Don-up W. Hnkrzlu Ts--as I. Ensna 5 MC n/am:

3,469,791 GAS BURNER Warren H. De Lancey, Herbert G. Hays, and Donald W. Hartzeil, Elyria, @hio, assignors to American Standard Inc, a corporation of Delaware Filed Jan. 2, 1968, Ser. No. 704,968 Int. Cl. 1305b 7/00; F23d 13/24 U5. Cl. 239-4195 14 Claims ABSTRACT 033 THE DISCLOSURE The present burner comprises an inner slotted or perforated gas distributor tube and an outer ported flame tube, the blind ends of said tubes being connected together by a novel low cost cap structure.

This invention relates to gas burners, as are used for example in domestic furnaces.

The inner tube of the burner is slit or perforated for its full length, and dimples or projections of predetermined height are formed in one of the tubes, whereby the inner tube is allowed to spring outwardly so that the dimples maintain an accurate spacing between the tubes, even when the two tubes tend to expand non-uniformly due to thermal effects resulting from the location of the burner ports.

To provide precise metering of the gas flow the twotube burner is constructed so that the space between the tubes may be varied to a slight extent along he burner tube length; this gives a more uniform fire along the burner length.

A feature of the burner installation is a spring type mounting means trained between the burner and a fuel supply structure. This mounting means causes the remote end of the burner to interlock with a support structure, while at the same time permitting the burner to be readily removed for cleaning, repair or replacement. Due to its location the mounting means compensates for longitudinal thermal expansion and contraction of the burner.

An additional feature of the two-tube burner is the provision of multiple rows of flame ports in the outer tube and multiple rows of gas supply openings in the inner tube, whereby each row of flame ports is supplied with fuel flowing circumferentially from two directions in the space between the two tubes. This feature enables higher heat outputs to be achieved without resorting to larger tube diameters; additionally the use of multiple rows of flame ports may give better distribution of the flame pattern in relation to the heated surface area of the heat exchanger with which the burner is used (less likelihood of hot spots).

THE DRAWINGS FIG. 1 is a top plan view of a burner installation embodying the invention.

FIG. 2 is a sectional view taken on line 22 in FIG. 1.

FIG. 3 is a sectional view taken on line 3-3 in FIG. 2.

FIG. 4 is a transverse sectional view taken on line 4-4 in FIG. 2.

FIG. 5 is a sectional view taken in the same direction as FIG. 4, but through a variation of the invention.

FIG. 6 is a fragmentary sectional view illustrating an additional embodiment of the invention.

GENERAL ARRANGEMENT The burner, designated 18, comprises an inner cylindrical tube 2!; and an outer cylindrical tube 22. Fuel gas enters tube 2% in the arrow 16 direction, and flows longitudinally within the tube toward end closure 34; primary air is entrained with the gas as it issues from the spud. A full length slot 26 in the lower surface of tube 20 directs "ice the mixture into the annular space 21 so that it flows upwardly around the tube 20 outer surface before reaching the flame ports 30 and 32 in the upper wall portions of tube 22.

Ignition of the burner may be accomplished by a flamecarrying hood structure 60 attached to the front or rear end of the burner; the drawing illustrates a rear end location. The hood structure receives its gas supply from the burner interior via passages 74 and 76, and a pilot flame (not shown) ignites the gas as it issues from a slot 82 in the hood structure.

In usual practice a number of the illustrated burners, each having a hood structure 60, are positioned side-byside to receive fuel gas from a common manifold 10. Each hood structure 60 transmits flame to its burner and to the hood structure on the next adjacent burner. In this way a number of burners are effectively lighted from a single pilot flame.

FUEL GAS SUPPLY There is shown a burner installation comprising a fuel gas manifold pipe 10 of general circular cross section. At spaced points along its length the manifold pipe is provided with bosses 12 which fixedly receive the fuel gas spuds 14, only one of which is shown in the drawings. The raw fuel gas flows longitudinally through manifold pipe 10, and thence turns into the individual spuds 14 into the burner it entrains primary air from the surrounding area.

BURNER PER SE Axially aligned with each spud 14 is an elongated tubular gas burner 18 comprising an inner cylindrical metal tube 20, and an outer cylindrical metal tube 22. The lengths and diameters of the tubes can vary, but illustratively the tubes can be about twenty inches long, the inner tube can have a diameter of about one inch, and the outer tube can have a diameter of about one and one quarter inches; the tube diameters can of course vary in an absolute sense, but there is an appropriate ratio between the tube diameters for a pressure drop feature which will become apparent hereinafter. The tubes are in practice much longer in relation to their diameters than would appear from the drawings. To clarify this, FIGS. 1 thru 3 are shown with breaks intermediate the ends of the tubes.

Inner tube 20 is formed from a sheet of steel which preferably has some springiness in it so that when it is formed into the cylindrical configuration it will tend to spring outwardly toward the surface of tube 22. This spring-out characteristic is made possible by correct choice of material and by forming a break or slit along the entire length of the tube. In FIG. 3 this break line is denoted by numeral 24; it includes an elongated slot or aperture 26 extending substantially the length of the tube, but terminating a short distance from the open tube end as shown in FIGS. 2 and 3. Slot 26 could if desired extend rearwardly to the tube end, thus eliminating the rearmost break line 24. Alternately the single aperture 26 could be replaced by a series of apertures separated by individual breaks or slits.

To keep the inner tube 20 accurately spaced from outer tube 22 the inner tube is preformed with outwardly projecting dimples 28; alternately some or all of the dimples could be formed as inward projections from tube 22. As shown in FIG. 4 there are a suitable number of dimples spaced circumferentially around the tube 20 and contacting the inner surface of tube 22. FIG. 4 is taken through one plane only of the tube, and in practice additional sets of dimples are provided at other longitudinal locations along the inner tube. Thus, with a twenty inch length tube there might be provided five sets of dimples spaced evenly along the tube length. These dimples cooperate with the spring-out nature of the inner tube to accurately space the outer surface of the inner tube from the inner surface of the outer tube.

Outer tube 22 is continuous about its circumference, but may in practice be formed with a seam (not shown) along its entire length. The tube may thus be formed from flat sheet metal, and at the same time stamped with two rows of flame ports and 32, as well as certain other openings, to be described hereinafter. The flame ports preferably extend substantially the entire length of tube 22 except for the tube end portions.

As shown best in FIG. 2, the two tubes 20 and 22 are connected at their right ends by a one-piece unitary cap structure 34 which has three diiferent diameters, indicated by numerals 36, 38 and 40. Cap portion 38 snugly telescopes within tube 22, and cap portion 40 snugly telescopes within tube 20, thus connecting the tube ends together and sealing the joint therebetween; the cap is preferably welded or staked to tube 22 but not to tube 20. The left ends of the burner tubes 20 and 22 are connected and sealed by forming the inner tube so that its end portion flares outwardly, as at 48. The flared portion thus fits snugly but removably within tube 22 to act as a seal and as a support.

BURNER MOUNTING Exposed portion 36 of cap 34 may be provided with slots 42 and 44 (FIG. 3) for insertion onto an angle iron-type support structure 46 which is a fixed part of the burner installation. Cap structure 34 thus performs a triple function, namely as a connection between tubes 20 and 22, as a sealing means between the two tubes; and as a mounting means for the rear end of the burner.

The front or left end of the burner may be mounted on the fuel gas spud 14 by means of a flat metal bow spring 50, whose mid-portion is provided with a circular opening formed by flanging the spring material axially, as at 52. The opposite ends of the bow spring are turned or deformed outwardly as at 54 to form. detents which snap into rectangular openings 56 formed in the wall of tube 22. The detents 54 project through slots 57 in the left edge of tube 20, but the retention shoulder for each detent is preferably formed by the opening 56 in tube 22.

Preferably the bow spring is preformed with its ends spaced further apart than shown in FIG. 2. The bow spring thus tends to have its detents 54 lock into openings 56 when the spring is hand-installed. The inner tube 20 must of course be assembled into tube 22 with its slot 26 remote from ports 30 and 32; otherwise the annular space 21 will not serve its desired gas control function. To assure correct factory assembly the bow spring 50 is formed with one detent 54 wider than the other; also the different openings 56 and different slots 57 are of different widths. For example the upper detent 54, upper opening 56 and upper slot 57 (FIG. 1) are narrower than the lower detent 54, lower opening 56 and lower slot 57 (FIG. 3). This insures that tube 20 will not be installed in a position rotated 180 degrees from that shown in FIG. 2.

Preferably burner 18 is supported entirely by the gas supply manifold 10 and support structure 46. Thus, spring 50 transmits the weight of the lefthand portion of the burner onto spud 14, and no additional support mechanism is used. It will be noted that spring 50 occupies free space between burner 18 and fuel supply manifold 10, i.e., the spring is the sole device between the manifold and the burner. This arrangement enables burner 18 to be manually withdrawn away from structure 46 in the arrow 19 direction, thus removing slots 42 and 44 from structure 46 and incidentally compressing spring 50. The burner can obviously then be manipulated by an upward and rightward motion to remove the burner-spring assembly from the fixed gas manifold structure.

4 BURNER DISMANTLING Preferably the burner per se is formed so that inner tube 20 can be separated from outer tube 22 for cleaning, repair or replacement. Toward this end cap 34 is constructed as a snug lit in tube 20; no welding, soldering, etc., is used. Cap 34 is however preferably welded or otherwise permanently secured to tube 22 to preserve structural unity to the burner. Spring 59 can be dissociated from the burner by inward pressure on its U- shaped portions 51 incident to on-the-job removal of tube 20.

After removal of spring 50 the inner tube 20 can be removed from outer tube 22- by inserting a nail or similar pinlike element (not shown) through two radially aligned openings 53 in tube 20. Tube 22 is provided with slots 55 in its end edges which register with openings 53 to permit the pin-like element to be drawn leftwardly while tube 22 is held in a stationary position. The pinlike element may thus be used to draw tube 20 out of tube 22.

FLAME CARRY-OVER HOOD STRUCTURE In furnace installation a number of burners 18 would be arranged between manifold 10 and support structure 46. Normally, all of these burners would be ignited from a single pilot flame located adjacent one of the burners. To carry the flame from the pilot to the adjacent burner and from burner to burner, each burner is equipped with a hood structure 60 formed in the present instance by a single sheet of metal having two wall portions 62 and 64 doubled back onto one another in pancake fashion. As shown in FIG. 2, the lower wall portion 62 and upper wall portion 64 are joined by two connector sections 66, which could be a single elongated section if desired. Sections 66 are not hinges but are merely temporary connectors during assembly operations; two wall portions 62 and 64 are permanently secured together by spot welds 68.

Wall portion 62 is downwardly bulged-out in the area circumscribed by line 70, while wall portion 64 is bulged upwardly in the area circumscribed by line 72, the two bulged-out areas thus forming a central gas plenum chamber 73 for receiving a supply of gas from the burner on which the hood structure is mounted. Although not clearly shown in the drawing, the lower surface of the bulged-out portion 70 is concaved to conform with the surface contour of burner tube 22, thus permitting the hood structure to be welded on and sealed to the burner tube.

Fuel gas is supplied to the hood structure plenum chamber through a small port '74 in tube 29, and a passageway formed by two registering openings 76 in burner tube 22 and hood wall 62. The peripheral wall areas of the hood structure rightwardly of the plenum chamber are facially engaged to form a seal, but the peripheral wall areas leftwardly of the lines designated by numerals 78 and 80 are spaced apart to form a slot-like passage 82. This slot-like passage has an appreciable length in the arrow 84 direction, which causes it to act as a restrictor for preventing flashback of the flame into the plenum chamber. Preferably the hood structure extends crosswise of the burner tube as shown in FIG. 1 so that portions of the slot-like passage 82 are near the port structure for the next adjacent burner. Passage 82 thus propagates a flame not only along the burner ports 30 and 32, but also onto the hood structure for the next burner in the series.

GENERAL MANNER OF IGNITION The fuel gas issuing from spud 14 entrains a quantity of primary air from the surrounding space, and the fuelair mixture is propelled by the manifold pressure into tube 20. The rush of gas is predominantly axial, and a major part of the gas flow piles up against the inner surface of cap 34, where it then flows upwardly through passages 74 and 76 into hood structure 60. Assuming a pilot flame at the outer surface of slot 82, there will be ignition at the hood structure, and propagation of flame rightwardly along the ports 30 and 32; thus the rightmost ports 30 and 32 will ignite first and the leftmost ports will ignite last. Gas mixtures which have predominantly filled the tube 20 are forced downwardly through the slot-like aperture 26 extending substantially the full length of tube 20. The mixtures then flow upwardly around the outer surface of tube 20 in the annular space 21 before reaching the main flame ports 30 and 32.

The location of the hood structure at the rear of the burner is beneficial in promoting quick ignition with lessened puff. This is believed due to the fact that the gas flows from the right closed end of tube 20 directly into the hood structure without having to build up a return or reverse velocity pressure as may be the case when the hood structure is located at the entrance end of the burner.

GAS METERING Preferably the cross section of the passage formed by space 21 is somewhat less than the total cross section of the flame ports 30 and 32 or of the supply aperture 26. Thus, the flame ports may be two rows of circular holes inch in diameter, spaced on inch centers; the slot 26 may have a width of about 7 inch; and the annular space 21 may have a radial dimension of only about .06 inch. With this arrangement the restriction in the gas passage system is supplied by passage 21. This passage is of appreciable circumferential extent or length. It thus pro vides a restriction or metering means, which causes the pressure within tube 20 to be greater than the pressure at the ports 30 and 32. Because of this pressure relationship there is little possibility of flame flashback into the burner. Also, experiments show that the burner produces a desirably short, hard, blue fire symptomatic of good airfuel mixing and distribution. In the illustrated burner the cross section of passage 21 is accurately maintained by the aforementioned spring-out nature of tube 20, the full length break 24 and the controlled-height dimples 28.

In elongated burners of the illustrated type the motion of the gas in tube 20 is to a large extent axial in nature, which tends to cause more gas to be delivered to the rightmost or rear ports than is delivered to the leftmost or front ports. To minimize this tendency the annular passage 21 is maybe slightly tapered from left to right. Thus, the leftmost dimples 28 might have a height of about .0625 inch, the next set of dimples might have a height of about .0575 inch, and so on, with the rightmost dimples being about .0475 inch. This taper is not large but is sufficient to provide a substantially uniform flame height along the burner. We have found that the controlled height dimples will in practice all engage the surface of the outer tube even though they are of varying height; thus, they will provide the desired spacing between tubes.

During burner operation the upper surface areas of tube 22 will be at higher temperatures than the lower surface areas of tube 22 or tube 20 because the flame heat is concentrated on the top side of tube 22. There may thus be some thermal distortion of the outer tube. With very long burner tubes there might be some undesirable stress build-up or change in passage 21 dimension. However the dimples 28, together with the split nature of tube 20, allows the inner tube to follow or distort with the outer tube so that the annular passage 21 maintains its design dimension irrespective of tube Warpage.

FIG. 5 VARIATION FIG. 5 is taken through a burner which is similar to the FIG. 1 burner. Thus, the FIG. 5 burner utilizes an outer tube 22:: and an inner tube 20a spaced apart by dimples similar to dimples 28; the dimples are not shown in FIG. 5.

In the FIG. 5 burner inner tube 20a is split, as at 24a, for its full length, to provide the spring-out characteristic previously mentioned. However, instead of a single gas discharge slot 26 the tube 20a is provided with three gas discharge slots 26a, 26b and 260. The purpose in using three slots instead of a single slot is to increase the amount of gas supplied to the annular space 21, for thus increasing the capacity of the burner and its heat output without resorting to a larger tube diameter.

The ports 30 and 32 may have greater diameters than the corresponding ports in the FIG. 4 embodiment; additionally the FIG. 5 ports 30 and 32 may be spaced somewhat further apart. As shown in FIG. 5 port 32 is at about the 2 oclock position, openings 26a are at about the 5 oclock position, openings 26b are at about the 7 oclock position, ports 30 are at about the 10 oclock position, and openings 26c are at about the 12 oclock position. Opening 26c supplies gas to both ports 30 and 32, opening 26a supplies gas primarily only to port 32, and opening 26!; supplies gas primarily only to port 30. The arrangement of openings and ports is such that each port 30 or 32 is supplied with gas flowing in space 21 from two directions. In this way different sections of space 21 perform as metering passages while still achieving a high flow rate through each flame port 30 and 32. The capacity and heat output of the burner is thus increased without flame nonuniformities.

FIG. 6 VARIATION In the FIG. 6 burner the flame carry-over hood structure 60 is positioned adjacent the entrance end of the tube assembly, rather than near the downstream end as in FIG. 2; the actual hood construction may however be the same in each case. The reason for relocation the hood in FIG. 6 is that in certain burner installations the entrance end of the tube assembly is the only place available to receive the hood or to make the hood accessible for automatic or manual lighting purposes.

Preferably the inner tube 20 in FIG. 6 is provided with a struck-down tab which has the function of deflecting a portion of the oncoming gas toward openings 76 for thus accomplishing rapid flame propagation. The tab therefore minimizes the aforementioned problems of ignition puff and reverse velocity mentioned earlier herein. The tab dimensions may be varied, but as an example, when the inner tube 20 has a diameter of about one inch tab 90 may have a length of about one inch and a width of about one quarter inch; the formed slot 92 would of course necessarily have the same dimensions as the tab.

FIG. 6 illustrates an alternate method of mounting the burner tube assembly shown in FIG. 2. In FIG. 6 each tube assembly has its entrance end area resting in a semicircular notch or seat formed in the upstanding leg of a transversely extending angle iron 94. To hold the tube assembly down on the angle iron there is provided a metal strip 96 having a turned-out upper end portion 98 extending through a slot in tube 22; a screw 99 threads into an opening in angle iron 94 to retain strip 96 in place.

Although not shown in FIG. 6, the rear end portion of the tube assembly may be supported on an angle iron 46 similar to that shown in FIGS. 2 and 3. The spacing be tween angle irons 46 and 94 would in practice vary somewhat from design value, and accordingly the slot position, etc., is chosen so that under perfect circumstances the strip 96 is angled or tilted as shown. This allows the screw 99 to screw down tight against strip 96 and take up any play or looseness.

It is claimed:

1. A gas burner comprising an inner elongated gas supply tube having gas discharge aperture means extending therealong, and an outer elongated burner tube having flame port means extending therealong; said gas supply tube having an entrance opening at one end thereof for admitting fuel-air mixtures to the supply tube interior; the two tubes being substantially coextensive in length, and the diameters of the tubes being such as to provide an annular space between the outer surface of the inner tube and the inner surface of the outer tube; the ends of the tubes remote from the entrance opening being closed whereby fuel-air mixtures are caused to travel longitudinally within the inner tube, through the discharge apertures, and into the space between the tubes before reaching the flame ports; closure of the remote ends of the tubes being effected by a sealing means which comprises a single unitary cap having a first large diameter portion closing the end of the outer tube, and a second small diameter portion closing the end of the inner tube.

2. The gas burner of claim 1 wherein the cap is a onepiece element.

3. The gas burner of claim 1 wherein said cap is provided with an exposed tubular end portion having slots therein for mounting one end of the burner on a fixed support structure.

4. The gas burner of claim 1 wherein the entrance end of the inner tube is outwardly flared to snugly telescope within the outer tube, whereby the tubes are connected at one end by the flared tube portion and at the other end by the unitary cap.

5. A gas burner comprising an outer elongated burner tube having flame ports extending therealong, and an inner elongated gas supply tube having at least one gas discharge aperture extending therealong; means sealing the tubes together at one end thereof; said one end of the inner tube being open to admit fuel-air mixtures to the burner, the aforementioned sealing means causing the mixtures to travel longitudinally within the inner tube and to then pass through the discharge aperture into the space between the tubes; a second sealing means closing the other end of the tubes; and means for accurately spacing the inner tube from the outer tube, said spacing means comprising a slit formed substantially along the entire length of the inner tube, whereby said inner tube is enabled to spring outwardly toward the outer tube along its entire length, and dimples formed at spaced points along at least one of the tubes, said dimples projecting from said one tube toward the other tube to engage same and thereby determine the spacing between the tubes.

6. The burner of claim 5 wherein the gas discharge aperture in the inner tube is formed by a single elongated slot extending along the inner tube for a distance corresponding generally to the portion of the outer tube which is equipped with flame ports.

7. The burner of claim 5 wherein the flame ports in the outer tube are circumferentially spaced from the gas supply apertures in the inner tube, whereby gas leaving the supply aperture is required to traverse a substantial portion of the inner tube circumference before reaching the burner ports.

'8. The burner of claim 5 wherein the total flame port area is greater than the total passage cross section provided by the space between the inner and outer tubes, whereby said space constitutes a passage restriction tending to prevent flashback into the burner.

9. The burner of claim 5 wherein the dimples are of graduated height, the dimples adjacent the closed end of the tube being shorter than those adjacent the open end of the tube whereby a tapered passage space is formed between the two tubes.

10. A gas burner comprising an outer tube having burner ports extending therealong, and an inner tube having at least one gas supply aperture extending therealong; said inner tube having a main portion spaced from the outer tube to provide a circumferential gas passage between the tubes, means for admitting fuel and air mixtures to the burner via one end of the inner tube; the burner ports comprising a first set of ports extending along the outer tube at approximately the 2 oclock position and a second port means extending longitudinally along the outer tube at about the 10 oclock position; the apertures in the gas supply tube comprising first aperture means extending longitudinally along the tube between the 10 oclock and 2 oclock positions, and a second aperture means extending longitudinally along the inner tube between the 2 oclock and 10 oclock positions.

11. The burner of claim 10 wherein the second aperture means comprises two sets of apertures, one set located at about the 5 oclock position, and the other set located at about the 7 oclock position.

12. A gas burner installation comprising a fuel supply structure and a support structure spaced therefrom; an elongated fuel gas burner having one end thereof interlocked with the support structure; and spring means detachably connected between the fuel supply structure and the other end of the burner; said spring means occupying space between the burner and fuel supply structure to permit the burner to be detached from the support structure by movement thereof toward the fuel supply structure.

1'3. The burner of claim 12 wherein the spring means comprises a bow spring having its mid-point connected with the fuel supply structure and its ends connected with the burner tube, said ends including outwardly projecting detents arranged to snap into retention openings in the burner.

14. The installation of claim 12 wherein the burner comprises an inner gas supply tube and an outer burner tube, one of said tubes having openings and the other tube having slots extending from one of its end edges for registry with said openings, whereby a tool can be inserted through the openings to withdraw the inner tube from the outer tube.

References Cited UNITED STATES PATENTS 3,156,292 11/1964 Ross 239419.5 3,198,238 8/1965 Hughes 239417.5 3,259,170 7/1966 Koehrer 239-4175 3,314,610 4/1967 Reznor 239417.5

EVERETT W. KIRBY, Primary Examiner US. Cl. X.R.

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