US2671507A - Radiant gas burner - Google Patents

Description

Patented Mar. 9, 1954 RADIANT GAS BURNER Charles W. Morck, Jr., Philadelphia, Pa., assignor to Selas Corporation of America,.Philadelphia, Pa., a corporation of Pennsylvania.

Application June 3, 1950, Serial No. 165,954

8 Claims.

The present invention relates to burners, and more particularly to a high capacity distributor or tip to be used With radiant cup type ceramic burners.

Radiant burners of the type with which this application is concerned are disclosed and claimed in Hess Patent 2,215,079, granted September 17, 1940. Burners of this type are formed of a block of refractory material that has a cupshaped depression in one face thereof. A combustible mixture of fuel and air is discharged into the base of the cup by a distributor member in a plurality of substantially'radially directed jets. The jets are ignited as they enter the cup and are completely burned therein. The surface of the cup is heated to incandescence to project radiant heat into the space to be heated, and heat is also supplied by the products of combustion that are discharged into the space from the cup.

Fuel is supplied to burners of the type under consideration as a complete mixture by'either a mixing machine or by an inspirator. In either case the mixture is vsupplied yto the cup in a series of jets by a distributor, as noted above. The distributor comprises a ceramicpiece which is formed with a plurality of passages terminating in substantially radially directed ports. Thecapacity of the burner is limited by the size or area of these ports and consequently the volume of fuel that can be delivered to the cup. vWhen the ports are increased beyond a certain optimum size the burner is liable to backfire. In any event the larger the ports the smaller .the turndown that can safely be obtained.

Another factor that enters into burner capacity is the pressure of the fuel supply. For a given total port area a givenpressureis requiredto force'a given amount ofV mixture through the distributor into the cup. When using .inspirators in particular, it is difficult `to attain lmixture pressures sufcient to supplythe mixture in` large volumes, or to have a large'capacity, for aigiven size burner.

It is an-object of the 'inventionftoprovide a radiant type burner in-which-the.;portarea for the mixture is appreciably increased -Without increasing the size ofthe individuahpassages. in the distributor or tip. It is a.further objectof the invention to provide -a distributor .orgitip-of a given size that has'aflarger number'ofports and total port area thanit'haspreviouslfy been possible to obtain.

An additional object of ythe invention is to provide a burner having ka larger capacityr `or one in which. a larger `volumeof vfuel can be burned at a given pressure, 'than has previously been obtainable.

The burner of the present invention uses a ceramic block withpthe cup therein of conventional form. The Adistributorthrough 'which the fuel passesto thecup. however. is of'a novel `design inthe manner in whichv the fuel ports and passages are formed. The distributor is made `of several ceramic parts so assembled that a plurality of axially displaced rows of ports are obtained. Each of these ports can be made small enough so that the danger of backring is-eliminated over a large turn-down range. The overall area of the ports is such that fora given diameter distributor the capacity of the vburner is materially increased Within any pressure range.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For abetterunderstanding of the invention, however, itsadvantages and specic objects attained with its luse, reference should be had to the accompanying drawings and descriptive matter in which II have illustrated and described a preferred embodiment of the invention.

In the drawings:

Figure 1 vis a sectional view of the burner;

`Figure 2 is an enlarged sectional view `offthe distributor;

Figure 3 is a Viewy on line`3-3 of Figure' 2;

Figurel is a view on line 4 4 of Figure 2;

Figure 5 is a sectional view of a modiedform of distributor; and

Figure 6 is a sectional view of a modified-form of burner in which the fuel is supplied byanainspirator.

Burners of the 'present type can be usedfin many different kinds of furnaces, andare used `in the Walls, oor or-roof. kWherever used the burner block itself is built into and forms an integral part of the furnace. For purposes of the present description it will be assumed that the burner is built into the wall of a furnace.

The burner is mounted in and forms a party-of the furnace side Wall ll. As shown most clearly in Figure 1, each burner comprises a lmolded block 2l of ceramic material which is'secured in position in one of the side Walls li 'by a suitable high temperature fire-brick cement .22. The block 2| may have different `portions thereof formed of refractory materials possessing different heat resisting and thermal conducting properties, so that each portion will possess the most desirable heat resisting and thermal properties for its particular position in the'block. The different portions of each block are compacted linto a single unitary structure by a suitable molding operation to provide a block 2| Whichis rectangular in cross-section.

Block 2l is formed with a-centralpassager23 which extends therethrough and terminates at cup-shaped space 2li formed at the inner faceof the side Wall H. Within the passage-23 is `disposed a burner tube or sleeve 25 havingtheinner end thereof terminating at a region closelyadjacent tothe inner end of the passage "23. lThe `lic shell 36 of the furnace l2. ibustible mixture is delivered from a source of outer portion of tube 25 is formed with an outwardly extending shoulder 26 which fits snugly against a collar 21. The collar 21 may be a preformed and pre-fired body of porcelain which is thereafter united to the block 2l at the same time that the different portions of a block are united together by a firing operation. In order to position the tube 25 accurately in the passage 23, the surface of the collar 21 engaged by the shoulder 26 may be ground after the blocl; 2! is formed. The shoulder 26 of tube 25 is positioned in an enlarged opening or Well 28 extending from the outer end of passage 23 to the outer face of the side Wall Il. Within the outer end of burner ltube 25 is secured the inner end of a metal tube 2 9, as by cement, for example.

The outer end of the metal tube 29 is secured to the inner end of an internally threaded opening 3! formed in a hollow cover plate 32. Within the hollow cover plate 32 is provided a helical .coil spring 33 which is arranged to exert force against the outer end 34 of shoulder 26. In this l,

expansion of the different burner parts over the -wide temperature range encountered during The cover plate 32 operation of the furnace I2. is sufficiently large to close the enlarged opening or well 28 and is secured at 35 to the outer metal- A suitable comsupply such as a mixing machine through conduit 31 connected to the internally threaded opening 3l of the burner. The conduit 31 for supplying combustible gas mixture to the burner may be arranged in any desirable manner, and suitableA controls may be provided to adjust the pressure and the rate at which the combustible `gas mixture is supplied to the burner. rIhe combustible gas mixture passes through the short .length of flexible tubing 3G and metal tube 29 'the axis of the burner that the flames are closely adjacent to and follow the cup-shaped refractory wall to heat the latter to incandescence.

The distributors 38 are made of high temperlature refractory material and are preferably assembled from a plurality of parts as best shown in Figures 2 to 4 of the drawing. Referring to those figures it will be seen that there is provided a hollow cylindrical body member 39 having an enlarged portion 4l at one end thereof. This member is provided with threads 42 on its surface by means of which it can be threaded into the tube 25 through which the combustible mixture is supplied. The surface of the body 3e has formed in its periphery a plurality of grooves which extend axially of the member and turn radially outward as shown at 4t where they terminate at the surface of the enlarged portion 4|. It will be seen from an inspection of the drawing that when the distributor is threaded into tube 25 the ends 44 of these grooves will form ports that' are directed'ra'dially into the cup 24. Extending through the center of the body 39 is a plug 45 that is smaller in diameter than the opening in the body, but which is centered with respect thereto by means of a plurality of radially extending fins 46, shown herein as being fourrin number. These fins extend axially of the plug to provide a plurality of passages through the interior of the member 39 as shown at 49 in Figure 4 of the drawing. The plug is located axially with respect to the body member 39 by enlarged portions on the ends of the fins that engage against a beveled surface at the end of the body, as shown at 41. The other end of the plug projects beyond the member 39 and is threaded as shown at 49 to receive a cap 49. This cap is threaded on the plug to hold the three parts of the distributor tightly in assembled relation. The face of the cap which engages the right end of the member 39, as shown in Figure 2, is provided with an extension the same diameter as the enlarged portion 4|, which extension has formed in it a plurality of radial grooves 5I. These grooves also form passages through which the combustible mixture can be directed in a radial direction into the cup. The parts may be assembled so that ports 44 and 5I are in axial alignment or are displaced circumferentially with respect to each other.

In the operation of the burner disclosed herein the combustible mixture is supplied under a suitable pressure, that will vary with various installations, through the tube 25. The mixture then passes through the passages formed by grooves 5.3 as well as through the radial passages 5| into the cup 24 of the burner. The mixture discharged from passages 44 is ignited and sweeps along the entire surface of the cup as it is burning. The mixture from passages 5I starts to burn as it leaves the distributor and is carried along with the llames from the first-mentioned passages to increase the heat release from the burner. The uniform incandescence produced in the cup by the burning fuel is not apparently affected whether the two rows of ports are in axial alignment or staggered. Radiant heat of high intensity is projected into the furnace chamber and on the work contained therein from the incandescent cup. Heat is also produced by the hot products of combustion which pass from the burner into the space to be heated.

By providing a double row of fuel ports the total port area of the burner is increased without changing the area of individual ports. This means that the capacity of the burner for a given pressure of fuel supply is increased appreciably, but the fuel pressure at which backfire will occur is not increased.

When a burner of the type disclosed herein is used with a gas having a slow ignition characteristic, such as natural gas, there is a tendency for ignition to start at some distance from the mouth of the ports so that there is a cold ring in the cup closely adjacent to the distributor. This is overcome by having the cap 49 made of a diameter larger than the diameter of the portion 4l of body member 39. It is believed that the overlapping portion of the cap creates a turbulence in the mixture to speed up ignition at the exit of the passages so that the under surface of the overhanging part of the cap will be heated to incandescence and thereby serve to pilot the flames. In any event, with this construction the gas mixture is ignited immediately upon leaving the ports. In this fashion a slow burning gas is ignited as soon as it leaves ag-omiso? the ports, thus heating lup the ventire'cup and doing away with the above-mentioned 'cool Vring around the distributor.

When a distributor of the typedescribed above is used the diameter ofthe cap 49 islarger than the diameter of the tube 25 so that the distributor has to be -removed from the tube kbefore the latter can be withdrawn from the burner. When using the burner with-a gas having fast ignition characteristics, such as `city lgas, itfis not necessary to have the cap 'of the distributor larger in diameter than that ofthe -'tube'25 so that the entire assembly can be Withdrawn-from the wall of the furnace. Such va constructionv is shown in the distributor of Figure 5. This distributor also differs from that described above in that provision is made for increasing the number of rows of ports through which the mixture may be discharged.

Spaced between the cap 49a and 'the body member 39 is an annular member 52 which abuts the outer or right end of body 39 in Figure 5 of the drawing. This member is provided with a plurality of radially directed grooves 53 that form passages through which the mixture can be discharged into the cup. Cap 49a isprovided with radially directed grooves 54 similar to the grooves 5I described above. Therefore, the distributor of this embodiment -is provided with three axially displaced rows of ports through which the combustible mixture can be discharged into the cup of the burner. The mating faces of the disc 52 andthe head 49a are formed as shown at 55 so that the disc cannot be displaced radially with rrespect-to vthe cap. Thus, all of the parts are held in axial alignment'during the operation of the burner. Itshouldbe noted that whether the distributor is provided with two rows of ports as in Figure 2 or with three (or more) rows as in Figure 5 would depend upon the desired capacity of the burner, rather than upon the diameter of the cap or upon the type of fuel used.

In the burner described above, provision is made to supply a combustible mixture through tube 25 from any suitable source. With aconstruction of this type the fuel is 'generally supplied to a group of burners from a mixing machine which will proportion the air and gas correctly to produce a complete mixture. In' some cases it is desirable to have the mixture supplied individually to each burner rfrom an inspirator. A construction of this type is vshown in Figure 6 of the drawing. This figure also shows a slightly different arrangement of parts for forming the cup itself.

Referring to Figure 6 it will be seen that there is provided the burner block 2| asabove described. The inner cup member shown therein as 55 is in this case, provided with a frustroconical extension 51. Received by this extension in concentric relation therewith is a similarly shaped insert 58. To the left of the insert is a base block 59. With an farrangement of this type one or more inserts of 'various thicknesses can be used depending upon the thickness 'of the furnace walls. The block 56'forming the inner portion of the cup is of refractory material, whereas the base bloclrv 59 rcan very well be of insulating material. The insert 58 can be either insulating or refractory depending upon the temperatures of the furnace and the thickness of the furnace wall.

Surrounding the base 59isla casting 6I-that is ff'astenedfas by bolts `"61.*"totle shielding-36 'forming Vthe outer portion Vvof 'the furn'acefwall.

This casting -is provided withfa'n axialV 'opening through Whichthe Venturi-tube'f-63 'of an-in spirator'is inserted. '-Thetube isivprovided'with an integrallyformed 'fflange `64 that Yis bolted vto the castingA 6| as "at 65. 'It visin'oted 'that gaskets can be used between thelcasting-'and the lfurnace lwall as `well =as^ betweenft'he liiange 64 andthe casting in order to'insure a pressuretight `connection between "these parts. The .right vend of the inspirator"tube"f63"has threaded thereon Va distributor 'holderH 66 for-med of metal -alloy that can withstand'the high temperatures produced at the'baseof the "cu'p. The distributor 38,A which can take theform of the distributor disclosed in Figure I2 or the distributor 'disclosed in "Figure 5, is threaded -`into the holder'f'fas shown in the drawing.

The left end of the inspirator tube is provided with a web 46 that-holds `a* sleeve "68 through which gas is supplied under suitable pressure from a pipe 1l. VThe right end of rthe `sleeve S8 is provided withy lan orice member t9=having in -it 'an orifice of the proper diameter 'for :the type-:of gas that is being used and'for' the,- pressure under-'which the'g'as is supplied. 'Air for combustion is drawn through `the left'endfof the sleeve 63 bythe velocityfhead'of gasleaving the orice vmember 69. 1 The 'ratioffof g-asvand air forming the confibustibleiy mixture ncan 'b'e varied by changing the 'pkzssition 'of l'an 'air shutter 12 -with-respect to the openiendiof the inspirator tube-63.

The operation 'of 'insp'irator's` is'iw'ell-kno'wn. Gas under a suitable pressurefisf supplied through pipe 59 and'entrains fairfasrit-'leavesfthe orifice so 'that the complete 'mixtureis'fsupplied ltof'the distributor. Some-of 'thev pressure 'head "off the gas 4is lost dueto 'the'work expended in'entraining thev air `so that 4it is' impossible to'haver the same pressure immediately behind the distributor that is obtained' in the'sup'ply. v4'Because ofthe low pressures that are obtainable with'inspirators it` has vbeen extremelyvdiiiicult to Ifor'ce-enough of the? mixture 'through the'dist'ributor'i'nto the cup to obtain the desired heating effects. With a distributorof the 'type disclosed herein, however, the port "area is increased over what has previously been possible to-obtain 'fso that the capacity v'of the burner is greatly increased.

A burner of'theabove-desoribed type having a cupdiameter of 12` inches and l.providedwith a distributor A3 inches iny diameter was tested. The distributor had two'axiallydisplaced"rows of ports with 24 ports in'each row and a Vtotal port area of 1.41 squareinches. Inoperatingthefburner oncity gas having565 B. t. u.per cubic foot, gas'was supplied throughraninspirator at 9.5 pounds per square foot. The inspirator was so adjusted that an `air-gas ratio of 5 to 1 'was obtained -and the pressureiback of the distributor Vwas 2f*-6 inches'water column.v With suchoperation 621 cubic feet of gaswere burned per vhour in a closed combustion 'spacev to vrelease 351.000 B. t. u. A cup temperature of`2550 F. was obtained,*and at a cup temperature of 2200" Fjbackre occurred at inch of ywaterfcolumri pressure back of the distributor. g

From'the above description? itwill' be's'een' that the -novel distributor member described herein may be used with radiant typelburne'rs to increase the'capacitythereo The parts of the distributor may easilyy'be formed off-suitable 'high 'temperaturamaterial ls ch -asj a-'mullite eompo'sitionby standard ceinicmetlods. -'fI-`he"fp2rts`f'-f te distributor may be assembled before ring or may be assembled after ring and then cemented together. In either case the result is a substantially one-piece construction. Distributors of the type described are preferably used in burners of i' relatively large size and are usually three inches or more in diameter.

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, as set forth in the appended claims, and that in some cases certain features of my invention may be used to advantage without a corresponding user of other features.

What is claimed is:

l. A burner comprising in combination a block of refractory material having a cup-shaped depression in one face thereof and an opening extending from the base of the cup t an opposite face thereof, a cylindrically shaped distributor member formed with a plurality of grooves on its surface extending axially from one end thereof and terminating near the other end thereof, said member being formed with an axial passage extending from said one end to a point nearer said other end than said grooves terminate, said member having a plurality of passages extending radially from the surface thereof to the end of said axial passage, and means to hold said member in the opening of said block with the ends of said grooves in said cup.

2. A distributor for a burner comprising a cylindrical body having a first portion of a first diameter extending from one end toward the other, and a second portion of a larger diameter joining said first portion, the surface of said first portion being formed with a plurality of axially extending grooves which bend in a radial direction to terminate at the surface of said second portion, said member being formed with an axial bore extending from said one end, and a plurality of radial passages extending from the surface of said second portion to said axial bore.

3. The combination of claim 2 in which said body has a third portion of larger -diameter than said second portion and joining the same, said third portion extending radially outward beyond the point at which said passages terminate.

4. A distributor for a burner comprising a tubular part having an enlarged portion on one end thereof, a plurality of axially extending grooves formed on the exterior surface of said part, each groove extending from one end of said part and terminating in a substantially radial direction at the surface of said enlarged portion, a cylindrical member having axial anges thereon received in the bore of said part and having a portion extending beyond the same, said flanges engaging one end of the part to locate the cylindrical member and part relative to each other, and a cap having a fiat face attached to the extending portion of said cylindrical member and engaging with its face the end of said enlarged portion of said part to close the same, said cap being formed with radial grooves on its face, the radial grooves extending from the edge of the cap to the central opening of said part.

5. The combination of claim 4 in which said cap is larger in diameter than said enlarged portion of said part whereby the cap extends beyond the Outer, #met Said, radial grooves.

6. The combination of claim 4 in which there is provided an annular member between said part and said cap, said annular member being formed on the face thereof engaging said part with a series of radially directed grooves forming passages from the central bore of said part to the surface of said annular member.

'7. In a burner, the combination of a block of refractory material having a cup-shaped depression formed in one face thereof and an opening extending from the base of the depression to an opposite face thereof, a tubular member received in said opening and through which fuel is supplied, fuel distributing means mounted on the end of said member and including a ceramic disc having opposite flat faces and an opening in the center thereof and a plurality of radially extending grooves formed on one face thereof extending from said opening to the periphery of the disc, cylindrical means having an axial opening and a flat face extending substantially perpendicular to said opening and of the same diameter as said disc, the grooved face of said disc engaging the fiat face of said cylindrical means to form a plurality of radially extending passages, a ceramic cap having the same diameter as said disc engaging the opposite face of said disc, means to fasten said cylindrical means, said disc and said cap together as a unit, and means on said cylindrical means to mount said unit in the end of said tubular member and coaxial thereto so that the outer ends of said passages are in said depression adjacent to the base thereof, whereby fuel can issue from said passages into said depression in a plurality of radially extending jets to be burned therein.

8. A fuel distributor for a burner comprising a tubular member through which a fuel and air mixture is supplied, means attached to said member to discharge the mixture in a plurality of substantially radially directed jets including a part in threaded engagement with said tubular member, said part having an axial opening and a flatl face perpendicular to said opening, an annular ceramic disc having flat faces the same diameter as the face of said part, said ceramic disc being formed on one face thereof with a plurality of radial grooves extending from the center to the periphery thereof, said grooves being at least as wide at the periphery of the disc as they are at the center thereof, a cup shaped ceramic cap member having a flat face the same diameter as the face of said part to close the opening in said disc, said face being provided with grooves extending radially from the periphery to the center thereof and means holding said disc with the grooved face thereof against the dat face of said part and the grooved face of said cap member against the opposite face of said disc, said holding means extending centrally of the assembly between said part and said cap.

CHARLES W. MORCK, JR.

References Cited in the le 0f this patent UNITED STATES PATENTS Number Name Date 819,018 Machlet Apr. 24, 1906 1,584,210 Brunow May 11, 1926 2,105,533 Hess Jan. 18, 1938 2,474,313 Hess June 28, 1949 2,570,554 Henwood Oct. 9, 1951 FOREIGN PATENTS Number Country Date 589,316yw Great Britain Sept. 4, 1941

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