US3083759A

US3083759A - Radiant cup gas burner

Info

Publication number: US3083759A
Application number: US679118A
Authority: US
Inventors: Williams John Roger
Original assignee: Selas Corp of America
Current assignee: Selas Corp of America
Priority date: 1957-08-13
Filing date: 1957-08-13
Publication date: 1963-04-02
Anticipated expiration: 1980-04-02

Description

April Z, 1963. J. R. WILLIAMS 3,083,759

RADIANT CUP GAS BURNER Filed Aug. 15, 1957 Flai INVENTOR. JOHN ROGER WILLlAMS ATTORNEY.

United States Patent Office 3,083,759 Patented Apr. 2, 1963 3,083,759 RADIANT CUP GAS BURNER `lohn Roger Williams, Ambler, Pa., assigner to Selas Corporation of America, Dresher, Pa., a corporation of Pennsylvania Filed Aug. 13, 1957, Ser. No. 679,118 1 Claim. (Cl. 158-113) This application is a continuation-in-part of my application Serial No. 252,285, filed October 20, 1951, now abandoned.

The present invention relates to gas burners, and more particularly to gas burners that are intended to be used with gas fuels .having a slow llame propagation speed such as natural gas or propane, yfor example.

Radiant burners of the type with which this invent-ion is concerned Iare well known, and form the subject matter of Patent 2,215,079 issued September 17, 1940. In those burners, as with the present burner, fuel in the form of a complete mixture of gas and air is supplied from a distributor member into the base of a refractory cup in a plurality of jets. These jets of fuel are ignited and burn completely in the cup to heat the latter to incandescence, thus providing a source of radiant heat. When the fuel comprises manufactured gas, or other gas of high hydrogen content, the burners can be started in operation at once with a relatively high fuel pressure. When a slow burning fuel, such as natural gas is used, however, difficulty is frequently encountered in starting the burner up.

In some cases, the burner cup is provided with a number of concentric `grooves such as is shown in Patent 2,339,477, issued on January 18, `1943. These grooves serve to increase the radiating surface of the cup. The corners between the grooves reach incandescence faster than does a smooth surface, and thereby speed up the process of getting the Iburner into operation. They do not, however, have any effect upon the action of the fuel jets or upon the care that is required in controlling the fuel pressure in starting up a cold burner with natural gas.

AIt is indicated above, that the present burner is particularly designed for use with gas having a slow flame propagation rate. Natural gas, for example, has this characteristic, and as a result, it has been hard to find a burner which will operate satisfactorily from a cold start when natural gas is used as .a fuel. Ordinarily, with burner-s of this type, it is necessary to preheat the burners or to start them off with the fuel supply .at a very low pressure and to keep the pressure low until the cup has been heated to incandescence. Thereafter, the fuel pressure can be increased slowly and watched carefully to make sure rthe flames are not blown away. The present burner, however, has the characteristic when ibeing used with natural gas, of immediate ignition. The burner will operate atfull pressure, from the very start, even when it is cold. Another defect of ordinary burners, when natural gas is used as the fuel, is that the llames will leave the distributor, even though the cup is hot, when the fuel pressure is increased substantially. This results in reducing the incandescence of the cup near the point of fuel 4introduction so that the total Iamount of heat supplied by theburner itself `is considerably reduced.

In accordance with the present invention, the surface of the burner cup may be either smooth or grooved. In

either case, the cup is provided adjacent to the `distributor with a plurality of concentric ridges over which the jets of fuel mixture lare directed. These ridges serve to create low pressure areas into which a portion of the mixture is drawn. The fuel mixture that is pulled into and delayed in these areas is moving at a velocity below the rate of llame propagation, therefore, the fuel in these areas can burn and act as a pilot for the remaining portions of the mixture. With a construction of this type, a burner using natural gas as a fuel can be started cold with the fuel being supplied at full pressure. The flames from each jet also burn closer to the exit of the distributor, thus increasing the radiant area of the cup.

It is an object of the invention to provide a radiant cup type of burner in which the cup contour is such that a portion of the ow of fuel is delayed enough to secure immediate ignition.

It is a further object of the invention to provide a radiant cup type burner that may be used with a fuel having a slow flame propagation speed in which the cup is so contoured that the time required to start the burner up is decreased and the stability of its operation is increased.

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 specication. For a better understanding of the invention, however, its advantages and specific objects attained with its use, reference should be had to the accompanying drawings and descriptive matter in which EI have illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. l is a sectional view of one form of the burner;

FIG. 2 is a plan View partly in section of the distributor taken on line 2-2 of FIG. l; and

FIG. 3 is a sectional view of a different embodiment of the invention.

Referring to FIG. 1, there is -shown a 'burner block 1 that may be made of any suitable high temperature, refractory material, such `as Zircon, for example. This block may have any necessary shape such as square, round or hexagonal that is required for the furnace in which the burner is being used. Its shape will depend upon the manner in which the burners are placed in the furnace and upon the number of burners that are to be used. The upper face of the block 2 as shown in the drawing, is mounted in the refractory wall of a furnace and flush with the surface thereof. The lower face 3 of the block, which has an enlargement 4 around its edge, is generally embedded in the refractory wall of a furnace and is held therein in a convention-al manner.

The face 2 of the burner block is provided with a cupshaped depression 5 whose contour varies from being vsubstantially perpendicular to the face 2 at its outer edge to being substantially parallel thereto at .its base. 'I'he block is provided with an opening 6 extending from the base of the cup to the opposite face 3 thereof. Moulded in the surface of this `depression is a first concentric ridge 7 that is adjacent to the opening 6, and a second concentric ridge 8 that is located beyond the ridge 7 but still on what could be called the base of the cup. These ridges form on the cup surface, a plurality of depressions or valleys 10, 11 and 12 between the

ridges

7 and 8.

From an inspection of the drawing, it will be seen that the contour of the cup is divided generally into two secspear/s tions at different angles to 'the axis of the cup. The first section extending along line 13 from A to B is at an angle to a plane perpendicular to the axis of the burner, and the Second `section extending from B to C, the edge of the cup, is at a greater angle to said plane; in fact, it approaches a line perpendicular thereto. The height of the outer end of section AB is slightly less than one-half the depth of the cup, and should be within the limits of from one-half to one-eighth of the depth. The ratio of the lengths of a projection of these sections on a horizontal plane perpendicular to the burner axis is shown as being substantially 6 to 1. The length of a projection of `section BC on said horizontal plane should be within the limits of from one-fourth to one-twelfth of the length of a projection of section AB. The ridges are substantially sine waves and are completely formed in the curve section AB. The wave length of the ridges or from the low point on 'a valley on one side of a ridge to the low point on the valley on the other side of a ridge (from the end of lead line 10 to Vtheend of lead line 11 on the left of FIG. 1) covers substantially one-third of the length of a projection of section AB on said horizontal plane. The limits of size of the ridges should be from one-half to one-fifth of the length of the projection of section AB.

Fuel is supplied to the cup by a distributor consisting ofa cylindrical tip holder 14 that may be either ceramic or metallic depending upon the type of furnace in which the burner is used. This holder has, threaded into its upper end and projecting into the base of the cup, a ceramic distributor tip 15. The distributor tip has formed around its edge a plurality of slots 16 extending axially thereof which slots bend in a generally radial direction toward the surface of the depression as shown at 17. By reference to FIG. 2 of the drawing, it will be seen that the material of the distributor between the slots 17 is tapered at the discharge edges thereof so that the slots are flared as indicated at 18 on the drawing. It is noted that the distributor tip has formed in its end a socket 19 into which may be placed a tool for inserting and removing the tip from the holder.

In the operation of the present burner, a combustible mixture of fuel, such as natural gas, and air is supplied through the tubular distribution member 14. As the fuel flows through this member, it is divided into a plurality of substantially, radially directed jets by the slots 16 of the distributor tip 15. These jets, as shown diagrammatically in the drawing, are projected outwardly along the surface 0f the cup substantially parallel to the line 13 indicated at the right of the distributor in FIG. 1. Because of the fact that the

ridges

7 and 8 have between them depressions or valleys 10, 11 and 12, there are created a plurality of concentric low pressure areas into which some of the fuel mixture flows as shown by the dotted lines. The mixture in the depressions is at a velocity below the rate of llame propagation for the fuel mixture and will ignite and burn at these points. The fuel burning in the depressions serves as a pilot to light the main jets, and to rnaintain combustion of these jets from the time they leave the slots of the distributor tip.

With previous burners, it has been necessary to supply fuel at pressures as low as three and four inches of water column in order for them to burn when the cup itself is cold. The present burner, however, can be lit from a cold start when fuel is supplied at a pressure as high as 32 inches Water column. Due to the fact that the fuel burning in the low pressure areas will ignite immediaetly and pilot the main jets, the cup is heated rapidly to incandescence and will attain a temperature in the order of 2500 to 280()o F. within a few minutes. All of the fuel burns in the cup so that only hot products of combustion are discharged beyond the surface 2 of the burner block. This means that the burner can be placed close to the work thereby increasing the amount of heat that is transferred to the work without danger of the work being burned by the llame. Furthermore, it has been found that the Pressure 0f the fue! `can be increased as high as 79 i or 8O inches water column without any noticeable tendency for the flames to move away from the exits of the supply slots. rIhis means that the entire surface of the cup is heated to incandescence with a corresponding amount of heat 'being delivered lby the cu-p to the work.

In FIG. 3, there is shown a burner that operates in the same fashion as the burner described above but differing therefrom in the manner in which the cup-shaped depression is formed. As shown in this figure, the depression Sa has steeper sides 21 than was the case with the depression 5 of the burner of FIG. 1. The sides continue straight for a short distance before curving rather abruptly in a generally horizontal direction toward the center opening 6. It will be seen that in this form of the invention, there are provided three concentric ridges, 22, 23 and 24, which form between them and with the surface 21 a series of four valleys or depressions, 26, 27, 28 and 29. The dotted line 31 drawn in the right side of this figure, indicates more clearly the formation of the ridges and depressions in the surface of the cup.

In the form of the invention shown in FIG. 3, the contour of the cup, in section, also has two sections AB and BC at different Iangles to the axis of the cup. The first of these, AB, extending along line 31 is at a lesser angle to a plane perpendicular to the axis of the burner than is the section BC. As in FIG. l, the section BC approaches a perpendicular to said plane, and is shown as being more nearly perpendicular than is section BC of FIG. l. The heighth of the outer end of the section AB is slightly less than one-quarter of the depth of the cup, and is within the limits set forth above. A projection of section BC of FIG. 3 on a horizontal plane perpendicular to the axis of the burner shows that its length is substantially oneeleventh of the length of a projection of section AB on the same plane. This is within the limits set forth above. In this case, also, the ridges, lare completely formed in the curve section AB. A projection of each complete ridge on said horizontal plane shows that its length is slightly less than one-third of the length of a projection of section AB on said plane. This is within the limits for the size of the ridges set forth above. In this case, as shown on the drawing, the outwardly flaring portions of the

ridges

22, 23 and 24 are substantially flat and of equal length and are substantially parallel so that they will form plane sections of concentric cones,

This form of the invention operates in the same manner as that previously described. In starting the burner, fuel may initially be supplied at normal operating pressure. The low pressure areas formed around the depression by the valleys and ridges delays or traps enough fuel to insure its immediate ignition. The burner will operate with a steady and even heat. With this form of burner, las well as that of FIG. l, the cup does not exhibit any noticeable hot spots, but is evenly heated around its surface. This characteristic is enhanced when the burners are used in a closed furnace over the satisfactory performance that is obtained when they are tired in the open.

While in accordance with the provisions of the statutes, I have illustrated and described the best form of embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in the form of the apparatus disclosed without departing from the spirit and scope of the invention set forth in the appended claim, and that in some cases certain features of my invention may be used to advantage without a corresponding use of other features.

What is claimed is:

In a fluid fuel burner having a feed means provided with passage means for projecting a combustible fuel and a combustion-supporting fluid outwardly in a generally cup-shaped pattern, a burner cup of refractory material having a generally cup-shaped cavity therein, said burner cup having a substantially central opening through which said feed means projects, said cup having a surface which, in cross-Section, has an inner surface portion which is slightly inclined relative to a plane perpendicular to the bumer axis and an outer portion of substantially greater inclination relative to said plane, said inner surface portion comprising a plurality of spaced-apart concentrically arranged ripples extending around said feed means and having in cross-section a surface shape of repeating Wave-formation, wherein said repeating wave `formation is substantially a sine Wave and wherein each of said sine waves has a wave length of about one-half to one-lifth of the radius of said inner surface portion.

References Cited in the tile of this patent UNITED STATES PATENTS Roberts Oct. 24, 1933 Hess et al. Jan. 18, 1944 Hess .Tune 28, 1949 Stalego Nov. 22, 1949 McCreery et al May 13, 1952