US2519956A - Gas burner with internal mixturedistributing baffle - Google Patents

Description

Patented Aug. 22, 1950 GAS BURNER WITH INTERNAL MIXTURE- DISTRIBUTING BAFFLE Valley Alfred Drout, Michigan City, Ind., assignor to Bastian-Morley 00., Inc., La Porte, Ind., a corporation of Indiana Application March 18, 1946, Serial N 0. 655,186

9 Claims.

This invention relates to gas burners and particularly to burners which are capable of operating satisfactorily throughout a wide range of gas pressures.

An object of the present invention is the provision of a gas burner which will automatically control, throughout the entire range of gas pressures used, from the lowest to the highest, the flow of air-gas mixture to and out of the burner ports in such manner as to prevent backfiring at low pressures and excessive flame height at high pressures.

Another object of the invention is the prvision of a gas burner capable of automatically controlling the flow of air-gas mixture to and out of the burner ports, which burner is simple and rugged in construction, which has no moving parts subject to wear or maladjustment and in which the burner head has no parts requiring adjustment either before or during use.

Another object of the invention is the provi sion of a gas burner capable of automatically controlling the flow of air-gas mixture to and out of the burner ports which is very small and compact relative to the amount of heat which it will produce and which, even at the highest pressure produces a. compact flame, which extends only a short distance above the top of the burner, whereby the burner can be placed closely adjacent the object to be heated and requires a relatively small combustion chamber.

A further object of the invention is the provision of a gas burner having automatic flame control means, which burner can be made by a relatively simple and inexpensive manufacturing operation and which requires few, if any, machining or assembly operations to produce.

A further object of the invention is the provision of a gas burner which can be formed of any one of a relatively large number of materials best suited to burn a particular gas or gases and which burner, therefore, can be made for use with a particular gas or gases, such as natural gas, manufactured gas, liquified petroleum gases or others.

Still a further object of the invention is the provision of a gas burner which will produce a series of small but intensely hot, individual and non-merging flames, which are closely spaced and which provide a concentrated but substantially uniform heating of the surface or area to be heated.

Further objects and advantages of the invention will appear from the following description and the appended drawings, in which:

Figure l is a top plan view of one embodiment of the invention;

Fig. 2 is a side elevational view of the burner shown in Fig. 1;

Fig. 3 is a vertical sectional view taken along the line 3--3 of Fig. 2 and showing somewhat diagrammatically the different flame conditions which exist respectively when the air-gas mixture is supplied at four different degrees of pressure, from the lowest to the highest pressures; and

Fig. 4 is a fragmentary end elevational view of the portion of the burner at one of the burner slots, and showing the flame in conditions similar to those shown in Fig. 3.

Referring now particularly to Figs. 1 to 4, inclusive, of the drawings, the burner includes a mixing tube I and a burner head supported thereon. The mixing tube I may be of any suitable conventional construction and accordingly is not illustrated in detail herein, it being noted that it has the usual adjusting means and is adapted to introduce, as by Venturi tube action, a suitable quantity of air into a stream of combustible gas to produce an air-gas mixture which will burn when ejected from the burner, and is provided with the usual arrangement for regulating the air-gas mixture.

The burner head preferably is formed separately from the mixing tube I and is mounted thereon by a depending flange or'skirt 2 which telescopes over the end of the mixing tube I and defines an inlet passage 3' leading into the interior of the burner head. If desired, however, the mixing tube, or a portion thereof, may be formed integral with the burner head. The burner head preferably is formed as a single unitary hollow member and, except as hereinafter specifically noted, may be made entirely by casting from a suitable metal. From an inspection of the drawings, and from the following description of the structure, it will become apparent that the burner head is of such form as to lend itself readily to forming primarily by casting. Since the burner head can be made without machining, it can be formed from any one of a large number of suitable materials, such as grey iron, bronze, aluminum, brass and many others. Accordingly, a material can be selected which will burn any one of a large number of different gases, such as natural gases, manufactured gases or liquified petroleum gases. On the other hand, where the burner is to be used with a particular gas, it may be formed of a selected material which is particularly suitable for use with such gas.

as by grinding.

The burner head, in the form illustrated in Fig. 1, includes a hub-like central portion 4, a rim-like burner ring 5 and a plurality of radially extending spoke-like connecting portions 6 extending from the central portion 4 to the burner ring 5. The central portion 4, connecting p01- tions 6 and burner ring 5 are hollow. and respectively define a central manifold chamber 1, communicating with the inlet passage 3, a plurality of radially extending manifold passages 8 leading from the central manifold chamber-1 andan elongated, annular manifold chamber 9 communicating with the radially extending manifold passages 8.

Formed at the periphery of the burner ring 5 is a series of closely spaced, narrow slots forming air-gas outlets or flame ports 10. The ports are arranged in generally vertical planes and are spaced apart distances which are relatively small with respect to the lengths of the ports so that adjacent ports are approximately paral- --lel. The ports I9 preferably are formed by a eral or side wall l2 of the burner ring 5. The

upper and lower end edges 29 and 2|, respectively, of each port I0 are inclined as shown.

This, together with the generally concave shape of the wall portions in which the port is formed, provides a port ill having an outlet which is .somewhat longer than the inlet and which consequently is of greater cross-sectional area.

A- raised bead 13 extends around the outlet of each port It and prevents overheating of the adjacent portion of the burner head in a manner which will be understood by those skilled in the art. Informing the burner, the outermost faces of the beads, that is, the upper face of that portion of each bead on the upper wall II and the side face of that portion of each bead in the side wall [2, preferably is leveled and smooth Thus, when the ports it are cut into the casting, the slots forming the ports are provided with sharp, even side edges which insure a smooth flow of air-gas mixture from the ports and an even, non-flickering flame.

Upstanding from the bottom wall [4 of the burner ring is a vertical baflle 15, the upper .end of which terminates short of the top wall H and in a position approximately under the upper between the top edge of the baffle l5 and the portion of the top wall H directly above the bafile 15 forms in effect a substantially vertically disposed orifice l9 through which the air-gas mixture must pass before passing from the inner annular chamber [1 to the major portions of the ports ID or into the outer chamber [8. The baflle I5 is so located that the upper end edges of the ports H) are a short distance inwardly of a vertical line through the baffle I5. Accordingly, the upper end portions of the ports adjarectly above the chamber.

cent the upper end edges 20 are in direct communication with the inner manifold chamber I1 and air-gas mixture can pass directly from the inner chamber I! to the upper end portions of the ports without passing through the orifice l9.

When the burner is connected with a source of combustible heating gas under pressure, the gas flows into the mixing tube where an appropriate amount of air is introduced into the gas stream and mixed therewith to form a combustible airgas mixture. The air-gas mixture passes from the mixing tube i into the burner head through the'inlet 3 and hence to the central manifold chamber 1 from which it flows by the radially extending passages 8 to the inner manifold chamber l1.

When the air-gas mixture is supplied under very low pressure, that is, only slightly above atmospheric pressure, it is caused to flow directly from the inner chamber I! to the adjacent upper end portions of the several ports I0 and out through these portions of the ports. The upper end portions of the ports not only are in direct communication with the chamber I! but are di- Thus, the air-gas mixture, being under very low pressure, and lighter than air, will tend to flow upwardly from the chamber l1 and will thus flow to and out through the inner ends of the ports. In addition,

the resistance offered by the orifice to the flow of air-gas mixture into the outer chamber it will tend to force the mixture to flow out of the ports at the upper end portions only and prevent spreading down the ports and hence this also assists in determining the effective length of the port. The direction of flow also may be infiuencedbyapproximately shaping adjacent wall portions of the burner, especially the inner side face of the baifie 15 as illustrated. The connecting passages 18 may, if desired, be formed to slope in a slightly upward direction toward the burner ring in order to assist in the flow of the mixture at very low pressures.

The length of that portion of each port which vis in substantially direct communication with the chamber I! and which is utilized to discharge air-gas mixture at the lowest pressure is relatively short. Accordingly, theflame that is produced by the gas issuing from this relatively short flame will burn evenly and smoothly and there will be no backfiring. However, owing to the low pressure under which the mixture passes from the ports, the flame will burn as a very low, soft flame having very little heating quality.

However, due to its steady, even flow and ability to resist backfiring, this flame serves ideally as a pilot flame.

The general relative condition of the flame produced when air-gas mixture is supplied under the lowest pressure is illustrated diagrammatically by line a in Figs. 3 and 4. This flame issues from. only the inner portion of the port and is low in height; it spreads laterally only a slight distance beyond the side edges of the port.

In Figs. 3 and 4 there is illustrated somewhat diagrammatically (lines a, b, c and d) the general relative sizes and forms of flames which are produced at four different air-gas pressures from the lowest to the highest. The diagram also indicates the general relative effective length of the port which is utilized in supporting flames at the four different pressures. While only four illustrative conditions have been illustrated, it will be understood that the pressures (and accordingly the corresponding flame conditions) may vary continuously throughout the entire range from the lowest to the highest pressures.

When the pressure under which the air-gas mixture is supplied to the burner head is increased, this will cause a corresponding increase in flow to the ports. The total minimum effective area of the ports which was adequate to pass all of the mixture when supplied under the lowest pressure is insuflicient to pass the greater flow of mixture resultin from the higher pressure. Accordingly, a back pressure will be built up at the ports which will compel the mixture to seek another outlet and it will, therefore, be

expelled from the ports at portions adjacent the portions utilized to pass the minimum flow of the mixture.

Owing to the greater velocity of the mixture at higher pressure, the mixture has a greater momentum and, therefore, tends to flow in more of a straight line substantially horizontally from the chamber I1 and thus flows through the oriflce l5 and outwardly across the chamber l8 to those portions of the ports ll] laterally (horizontally) opposite the orifice 19. In effect, therefore, the principal direction of flow of the stream of air-gas mixture (or what for convenience, may be termed the flow axis) tends ing supplied to the lower portions of the ports with a corresponding spreading of the flame downwardly along the ports.

The entire stream of air-gas mixture under these conditions does not pass directly from the inner chamber i! to the ports ID, as in the case of the lowest pressure, but a portion enters the outer chamber i8 and passes from those portions of the ports which communicate with the chamber !8. However, owing to the restriction to flow imposed by the structure, the increase in eflective port area (and the spreading of the flames down the ports) may not be such as to fully compensate for the additional flow of mixture, and the mixture will be ejected from the effective areas of the ports under higher pressure than when the mixture is supplied under lower pressures. The flame under these circumstances will not only burn from a greater length of port but will be somewhat thinner and harder than the flame which burns when the mixture is supplied under the lowest pressure.

A further increase in pressure of the air-gas mixture will cause additional back pressure at the ports, resulting in the mixture being compelled to back down into the outer chamber l8.

.Thus, a still greater effective port area is required to accommodate the flow of the mixture and the base of each flame spreads down along from adjacent the burner.

the corresponding port. The momentum effect, explained above, also becomes still greater, resulting in a greater proportion of the mixture being directed laterally outward from the oriflce. The flame thus burns from a substantial length of the side portion of the port as well as the top portion. As explained above, the restrictive action will cause the mixture to be supplied to the effective port areas under higher pressure and the resulting flame will be wider, but thinner and harder than the flames resulting from lower pressures. The flames resulting from two intermediate pressures are illustrated somewhat diagrammatically by the lines D and 0, respectively, of Figs. 3 and 4.

When the pressure is increased to the maximum, a substantial back pressure is built up which forces the mixture all the way down in the chamber is to fill this chamber under pressure. The mixture is forced out of all portions of the ports l0 and each flame takes the form illustrated diagrammatically by the line d in Figs. 3 and 4. This flame is a very thin, hard flame which is not substantially thicker than the port aperture. The flame at all times does not extend a very great distance above the top wall of the burner. An increase in pressure from a lower to a higher pressure does not result in a proportionate increase in the height of the flame above the burner. This is due to the fact that an increase in pressure causes the flame to grow downwardly along the port to compensate for the increase in pressure. Even at the highest pressure the flame does not extend a very great distance above the burner because a substantial proportion of the mixture is ejected laterally and burns in that portion of the flame having its base along the side wall of the burner.

The ports are spaced relatively close together, preferably at distances substantially less than the lengths of the ports. However, owing to the thin nature of the flames, they do not merge, but burn as individual flames completely separated by upwardly flowing columns of air drawn These columns of air are relatively thin and have a relatively high velocity but are substantially unimpeded and flow freely to supply adequate secondary air to insure that the mixture will be completely burned and maximum efficiency will be obtained.

Since the port outlets are of greater crosssectional areas than the inlets, and since the end edges taper outwardly, an expansion of the mixture is created as it flows through the ports, whereby, even at the highest pressures the base of the flame hugs the burner and is not blown away from the burner. This aids in insuring a steady, even and silent flame of maximum efficiency.

For the best operation of the burner, it is important that the relative dimensions of the ports it, the orifice l9 and the outer chamber l8 be properly selected. The total cross-sectional areas of the openings formed by inner edges (in lets) of all of the ports is less than the crosssectional area of the orifice. For the best operation, the ratio of total port inlet area to oriflee area should be approximately 1 to 2.5. The cross-sectional area of the orifice should be less than the horizontal cross-section of the outer chamber is; such ratio should be approximately 1 to 1.6. Best results are obtained if the ratio of the total cross-sectional area of the openings formed by the inner edges (inlets) of the ports to the area formed by the outer edges (outlets) is approximately 1 to 1.6. The foregoing ratios may be varied slightly in burners of various forms but for the most satisfactory operation, these ratios should be followed.

From the foregoing, it will be seen that the invention provides a simple, readily made structure which embodies automatically acting means for controlling the fiow of air-gas mixture out of the ports in accordance with the pressure under which the mixture is supplied. Since the mixture is at all times supplied to the effective areas of the ports at a rate at least as great as the ignition rate, no backfiring can occur. Moreover, the orifice and outer chamber provide a control action which insures smooth, stable flames with no flickering.

The slot form of the ports provides a narrow flame which increases or decreases in length along the burner as the pressure is varied, but does not vary greatly in thickness. Thus, it is possible to dispose the ports closely together and to provide a large number of ports in a relatively short length of burner head without likelihood of the flames merging. Thus a relatively large number of flames representing substantial heating capacity can be concentrated in a relatively small area. Moreover, the flames even at the highest pressures, do not project a very great height above the top of the burner and hence the vertical space required for the burner likewise is relatively small. In addition, the automatic control means is not only compact and requires little space but is disposed wholly within the burner head so that the latter need be little, if any, larger than a conventional burner. For the foregoing reasons the burner can be made very compact not only in length and width but also in height, and may be used in a relatively small combustion chamber.

The burner head comprises a unitary member which may be made by a relatively simple casting operation, the only operation other than casting being that of forming the port slots as by cutting and grinding. While the several dimensions of the device must be selected properly in order to produce the automatic control effect, they are not so critical as to require machining of the surfaces. Since no machining operations are required, except as mentioned above, and there is no assembling or adjusting required, the

burner can be made very inexpensively.

Since the burner head structure is a unitary one with no moving parts and no special adjustment of ports is necessary, either before or during operation, to obtain the automatic control of the flame, it will last during a long period of operation without becoming inoperative due to wear or maladjustment of the parts. The burner however is capable of operation with various gases, inasmuch as the air-gas mixture can be controlled in the usual manner by suitable adjustment of the mixing tube.

The invention is not limited to a burner of the particular shape and arrangement of parts illustrated but is subject to modification, especially in respect to the general shape of the burner head. For example, the burner head, instead of being formed as a circuit or ring, may be oval, square or in other shapes. Also, the burner need not be formed as a closed figure but be formed as a straight, elongated head having ports provided in diametrically opposite side walls thereof. Variations may be made in such form, as for example by providing a header portion having a plurality of branches extending therefrom, or as a partial circle or U-shape such as is well adapted. to permit; the burner to be disposed peripherally around a vertical upstanding portion of a device with which the burner is used.

Since the burner can be made in innumerable sizes and shapes, it is suitable for use in a large variety of devices where a gas heating element is required. For example, it is admirably adapted for use in ranges, space heaters, furnaces, heating systems, water heaters, boilers, refrigerators and others. The relatively small size of the burner and the low compact and concentrated flame as well as the complete combustion obtained render this burner suitable to uses where it is competitive with or even better suited than other forms of heaters, such as electric heaters.

I claim:

1. A gas burner comprising an integral, unitary member having a burner section formed with a substantially horizontal manifold chamher, said burner section being provided with a plurality of elongated, spaced flame ports formed in an exterior wall of said chamber and disposed in generall vertical planes and arranged in a series extending along said manifold chamber, and a baiile integral with and upstanding from the floor of said manifold chamber to define with the top wall thereof an orifice adjacent the upper end portions of said ports and to define with other wall portions of said burner section a space adjacent the remaining portions of said ports.

2. A gas burner comprising a hollow burner head having an elongate, substantially horizontal manifold chamber formed with an inlet for air.- gas mixture to be burned, a member within said manifold chamber and projecting upwardly from the bottom thereof to a pCint short of the top thereof providing an outlet orifice between said baflle and the upper wall of said chamber discharging horlzontally toward an exterior wall of said chamber when the airegas mixture is supplied to said chamber under intermediate and high pressures, and a plurality of elongate discharge ports formed in said exterior wall of said burner head, each of said ports having a generally vertical portion disposed outwardly opposite and spaced from said orifice for discharging air-gas mixture only when supplied to said manifold chamber Lmder intermediate and high pressures and each port having a generally horizontal portion above and substantailly in direct communication with said manifold chamber for discharging air-gas mixture from said chamber under all pressures.

3. A gas burner comprising a hollow burner head having wall formed with top, side and bottom portions, 2. series, of elongate flame ports formed in said wall, adjacent ports of said series lying in approximately parallel, vertical planes and each port having a principal portion in a e por n of sai wall and an upper end p tion in the adjacent top portion of said wall m ans ncludin an elongate, substantially horizontal manifold chamber extending in communicat on w h ai ports for conducting an airas mixture to said ports along a principally horizontal flow path when supplied to said chamber und ntermediate and relatively high pressures, whereby said mixture is discharged through both said principal and said upper end portions of said ports, and means including a generally vertical baflle in said manifold chamber adjacent but spaced from the side portion of said well in the path of flow of said mixture and extendin from the bottom portion to near the top portion of said wall providing an orifice for directing said mixture to said ports principally along an upwardly directed flow path when supplied to said chamber under relatively low pressures, whereby said mixture is discharged through only said upper end portions of said ports.

4. A gas burner comprising a hollow burner head having a wall formed with top, side and bottomportions, a series of elongate flame ports formed in said Wall, adjacent ports of said series lyling in approximately parallel vertical planes and each port having a \principal portion in a side portion of said Wall and upper end portion in the adjacent top portion of said wall, means including an elongate, substantially horizontal manifold chamber extending in communication with said ports for conducting an air-gas mixture to said ports along a principally horizontal flow path when supplied to said chamber under intermediate and relatively high pressures, whereby said mixture is discharged through both said principal and said upper end portions of said ports, and means including a baiile extending upwardly from the bottom wall of said manifold chamber to a line short of the top wall thereof for directing said mixture to said ports principally along an upwardly directed flow path when supplied to said chamber under relatively low pressures, whereby said mixture is discharged through only said upper end portions of said ports.

5. A gas burner comprising a burner head having a wall formed with top, side, and bottom portions defining an elongate, substantially horizontal manifold chamber having an inlet for airgas mixture to be burned, a series of elongate flame ports leading from said chamber, each lying substantially in a vertical plane and having a side portion formed in a side portion of said wall and a top portion formed in an adjacent top portion of said wall, and means for establishing a principally upward flow in said chamber toward said ports when said mixture is supplied under relatively low pressures, said means including a baflle extending upwardl from the bottom wall of said chamber to a line short of the top wall thereof to define with said top wall a, substantially vertically disposed orifice in said chamber between said inlet and the side portions of said flame ports, said orifice being in substantially horizontal alignment with the side portions of said ports and substantially vertically under the top portions of said ports.

6. A gas burner comprising a burner head having an exterior wall with top, side and bottom portions defining an elongate, substantially horizontal manifold chamber provided with an inlet for an air-gas mixture to be burned, and an interior wall extending longitudinally in said chamber from its bottom wall portion to a line short of its top wall portion and dividing said chamber into elongate inlet and outlet sections, said interior wall also providing a substantially horizontal orifice between said chamber sections, said exterior wall having formed therein a series of elongate flame ports extending in substantially vertical planes with a portion of each port formed in a side portion of said exterior wall in substantially horizontal alignment with said orifice and leading from the outlet section of said chamber for discharging air-gas mixture from said burner head only when said mixture is supplied to said manifold chamber under intermediate or high pressures, and each of said flame ports having another portion extending into the top portion of said exterior wall immediately above said orifice and leading substantially directly from the inlet section of said chamber adjacent the upper wall portion of said orifice for discharging air-gas mixture from said burner head when supplied to said chamber under low, intermediate, or high pressures.

7. A gas burner comprising a hollow burner head having an elongate, substantially horizontal manifold chamber provided with an inlet for airgas mixture to be burned, a substantially horizontal series of elongate flame ports formed in a side wall of said chamber with adjacent ports lying in approximately parallel vertical planes, and interior wall means dividing said chamber into elongate inlet and outlet sections and extending from the bottom of said chamber to a point short of the top thereof to provide a flow impeding orifice constituting the sole communication between said chamber sections, said orifice being disposed in a substantially vertical plane and in horizontal alignment with the central and upper portions only of said ports whereby, when said air-gas mixture is supplied to said chamber under intermediate and high pressures, it flows principally in a generally horizontal direction through said orifice from said inlet section to said outlet section and is discharged through said ports over a substantial portion of the length thereof, the upper wall portion of said orifice being disposed closely adjacent the upper end portions of said ports, whereby when said mixture is supplied to said chamber under relatively low pressures, it flows principally in an upward direction through said orifice and out through the upper end portions only of said ports without substantial impedance.

8. A gas burner comprising a hollow burner head having an elongate, substantially horizontal manifold chamber provided with an inlet for airgas mixture to be burned, a series of elongate flame ports formed in a side wall of said chamber with adjacent ports lying in approximately parallel, vertical planes, and interior upstanding wall means in said chamber and extending from its bottom wall to near its top wall defining an orifice adapted to discharge the air-gas mixture toward said side wall in a substantially horizontal direction, said orifice being disposed inwardly opposite the central and downwardly of the upper portions of said ports whereby, when said air-gas mixture is supplied to said chamber under low pressures it flows upwardly through said orifice and is discharged through said ports, and when supplied under intermediate and high pressures it fiows principally in a general horizontal direction in said chamber and through said orifice and is discharged through said ports.

9. A gas burner comprising a burner head having a wall formed with top, side, and bottom portions defining an elongate, substantially horizontal manifold chamber having an inlet for airgas mixture to be burned, a series of elongate flame ports leading from said chamber, each 1ying substantially in a vertical plane and having a side portion formed in a side portion of said wall and a top portion formed in an adjacent top portion of said wall, and means for establishing a principally horizontal flow of air-gas mixture in said chamber toward said ports when said mixture is supplied to said chamber under relatively high and intermediate pressures and for estab lishing a principally upward flow in said chamber toward said ports when said mixture is supplied under relatively low pressures, said means including a wall element in said chamber ex- REFERENCES CITED tending from the bottom portion of said Wall to he following references are of record in the near the top portion thereof and spaced inwardly file of this patent: of said side wall portion defining a substantially 5 UNITED STATES PATENTS vertically disposed orifice in said chamber be- N b tween said inlet and the side portions of said g 61 ,N Date flame ports, said orifice being disposed inwardly 3 wllhams 11 1911 opposite the side portions of said ports with its i'g g'g g gz gggf 31 er ort'on s bstantiall verticall under and a upp p 1 u y y 10 1,753,962 Lonergan Apr. 8, 1930 connected w'th the to ortions of said orts.

1 ALFRED 101 50 7 1,731,785 Kerr Nov. 18, 1930

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