US3198436A - Apparatus for supplying a plurality of fluids to a combustion zone - Google Patents

Description

1965 E. F. KURZINSK] ETAL 3,198,436

APPARATUS FOR SUPPLYING' A PLURALITY OF FLUIDS To A COMBUSTION ZONE 3 Sheets-Sheet 1 Filed Feb. 15, 1962 INVENTORS KURZINSKI ROBERT D. JONES By RICHARD REIDER EDWARD E JACK R. SPEARY A TT ORNEYA' Aug. 3, 1965 E. F. KURZINSKI ETAL APPARATUS FOR SUPPLYING A PLURALITY OF FLUIDS TO A COMBUSTION ZONE Filed Feb. 15 1962 3 Sheets-Sheet 2 INVENTOR' KURZINSKI JONES REIDER 6' ATTORNEYJ EDWARD F ROBE D RICH BY JACK R SPEARY Aug. 3, 1965 E. F. KURZINSKI ETAL 3,198,436

APPARATUS FOR SUPPLYING A PLURALITY OF FLUIDS TO A COMBUSTION ZONE 3 Sheets-Sheet 5 Filed Feb. 15, 1962 INVENTORS EDWARD F KURZINSKI ROBERT D JONES BY RICHARD REIDER JACK Rv SPEARY '6 G -e A TORNEYS' United States Patent lice 3,198,436 APPARATUS FOR SUPPLYING A PLURALITY 0F FLUIDS TO A COMBUSTION ZONE Edward F. Kurzinski, Allentown, Robert D. Jones,

Coopershurg, Richard Reider, Bethlehem, and Jack R. Speary, Allentown, Pa., assignors to Air Products and Chemicals, Inc., a corporation of Delaware Filed Feb. 15, 1962, Ser. No. 173,540

7 Claims. (Cl. 239-132) The present invention relates to apparatus for supplying a plurality of fluids to a combustion zone. The plural fluids in the combustion zone will ordinarily be in admixture with each other; and theymay be mixed as they emerge from the apparatus or may emerge separately from the apparatus and mix in the combustion zone. Examples of such plurality fluids are natural gas and oxygen, natural gas and air steam and oil, oxygen and oil, air andoil, et cetera. Another group of fluids with which certain features of the invention are useful includes a mixed combustible gas as one of the fluids, in which case one. of the fluids might for example be oxygen and another a mixture of oxygen and acetylene.

A major category of apparatus according to the present invention is burners, which are characterized in that the fluids emerging from the apparatus are combustible when mixed; and the invention will be illustrated by way of example in connection with a burner for use in a metallurgical furnace such as an open hearth furnace used for steel making. It is to be understood, however, that the invention is adaptable for use in a wide variety of other environments.

A major problem in the use of such apparatus arises from flashback or explosion. These undesirable phenomena can occur when a combustible mixture is fed through a burner at less than the flame propagation velocity, or when the pressure in the burner drops below the pressure in the combustion zone, or when the equipment is improperly handled. One solution has been to provide check valves in the various fluid conduits. However, check valves have heretofore been of only limited utility because they'function well only in passageways of circular cross section. In order to construct a strong but light weight and desirably small burner, it is often desirable to make the various fluid conduits concentric with each other, so that only the innermost fluid passageway will be circular and the others will be annular. In such cases, the check valves for the annular passageways must be moved upstream of the burner and lo- .cated for example in the supply lines that feed the annular passageways. But in this latter case, the entire volume of the annular passageway is then available for flashback or explosion.

Another solution to the problem of flashback or explosion has been to avoid forming a combustible mixture until the fluids are at or beyond the discharge end of the burner. This solution, however, has not been entirely successful in avoiding flashback or explosion and moreover has tended to result in less thorough mixing of the fluids when practiced with burners heretofore available.

Although these and many other expedients have been tried in an effort to overcome these problems of the prior art, none as far as is known, has been entirely successful when practiced commercially on an industrial scale.

Accordingly, it is an object of the present invention to provide apparatus for supplying a plurality of fluids to a combustion zone, characterized in that the possibility of flashback or explosion is at a minimum.

Another object of the present invention is the provision of such apparatus characterized in that the volume v of the arrows;

3,198,436 Patented Aug. 3, 1965 of the space in 'the apparatus in which flashback or explosion could occur is at a minimum. 7

Still another object of the present invention is the provision of such apparatus in which thorough mixing is achieved but the presence ofmixed fluids inside the apparatus is largely avoided.

Finally, it is an object .of the present invention to provide such apparatus which will be relatively simple and inexpensive to manufacture, easy to operate, maintain and repair, and rugged and durable in use.

Other objects and advantages of the present invention will become apparent from a consideration of the following description, taken in connection with the accompanying drawings, in which:

FIGURES la and lb show rear and forward end portions, respectively, in longitudinal section, of apparatus according to the present invention in the form of a burner for use in open hearth furnaces;

FIGURE 2 is an enlarged cross-sectional view on the line 2-2 of FIGURE. 1b, looking in the direction FIGURE 3 isan enlarged view shown. at the discharge end of the apparatus, that is,

at the extreme right of FIGURE 1b;

Referring now to the drawings in greater detail, and

first to the embodiment of FIGURES 1a1-3, there is shown apparatus for supplying a plurality of fluids to a combustion zone, in theform of a burner including inner tubular conduits 1 and 1', a concentric outer conduit 3, and a concentric outermost conduit 5. Conduit 1 provides a passageway 7 of circular cross-sectional configuration for the passage of one of a plurality of fluids to be supplied to a combustion zone, for example, natural gas or oil. The discharge end of circular passageway 7 is almost at the extreme forward end of the burner. Conduit 3 defines a fluid-passageway 9 of, annular cross-sectional configuration concentric with and encompassing circular passageway 7, for the passage of a further fluid to be supplied to the combustion zone, such as air, oxygen or steam. Outermost conduit 5 defines between conduits 3 and 5 a passageway 11 of annular cross-sectional configuration for the passage of nular tube ring 21 disposed between and secured to conduits 3 and 5 divides cooling water passageway llyinto the annular passageway proper and an annular header 23 for the reception of cooling water- A pluralityof elongated tubes 25 pass from header 23 through tube ring 21 and extend substantially full length .of the b urner to convey cooling water from header 23, down to the tip or discharge end of the burner, whence the cooling water returns outside of and between tubes 25 to outlet 19. Tubes 25 are spaced apart peripherally about passageway 11, as seen in FIGURE 2.

At its discharge end, the burner is provided witha tip 27 that includes an inner shell 29 and an outer shell 31. Shell 29 provides a closure for the discharge end of conduit 3, while shell 31 provides a closure for conduit 5, the cooling water passing in part between shells 29 and 31.

of one of the nozzles The fluids to be supplied to the combustion zone by the burner pass through and are discharged from a plurality of nozzles 33 that diverge from each other in the downstream direction. Nozzles 33 extend between and are secured to and supported by shells 29 and 31. A major portion of their length is thus exposed to the cooling water'that passes between shells 29 and 31 through the spaces between nozzles 33, so that the nozzles do not become overheated. Each nozzle 33. is characterized by a central passageway 35 that'communicates at its upstream end with circular passageway 7' of conduit 1' through a conduit 37. The upstream ends of conduits 37 pass through a tube-sheet 39 that supports them in the discharge end of inner conduit 1' and that seals the discharge end of conduit 1' except for conduits 37 Nozzles33 may for example be six in number, with their discharge ends spaced generally peripherally about outer shell 31. Conduits 37 diverge from each other between tube-sheet, 39 and nozzles 33.

The structure of the nozzles 33 is best seen in FIGURE 3. As is there shown, each central passageway 35 terminates downstreamin an enlarged end 41. A plurality of peripheral passageways 43 smaller than central passageway 35-surround passageway 35and dead-end adjacent the discharge end of nozzles 33.- However, these closed downstream ends of peripheral passageways 43 communicate with enlarged end 41 of central passageway 35 through a plurality of openings '45. In this embodiment an intermixing of the fluid streams conveyed through passageways 35 and 43 adjacent the discharge end of the nozzle 33. Actual intermixing, however, occurs, or is 'at least initiated, slightly upstream from the physical end of the nozzle. Openings 45 may be formed, for exam.- ple, by milling annular recesses or grooves 47 in the side walls of enlarged end 41 of passageway 35, the intersection of each groove 47 with each passageway 43 providing an opening 45.

The discharge end of conduit 1, and thus the annular passage 9' formed between conduits 1 and-3, terminates short of the shell 29 so as to provide an enlarged region or manifold 49 at the forward end of conduit 3 surround- ,ing the conduits 37. The passageway 9' thus communicates with all of peripheral passageways 43 through manifold 49, while passageway 7' is restricted to communication with passageways 35 through conduits 37 which pass through manifold 49.

A notable feature of the present invention is that adjacent the discharge end of the burner, the fluid in the innermost passageway 7 is diverted from passageway 7 to the outer passageway 9', while at the same time the fluid from passageway 9 is diverted to inner passageway 7', the fluids being maintained separate throughout the transfer. Thus, a first fluid moves through circular passageway 7 and a second fluid through annular passageway 9 to a crossover or transfer location adjacent the tip of the burner, whereupon it is the second fluid that thereafter moves through circular passageway 7- and the first fluid that moves through annular passageway 9'. The purpose of this crossover is to make 'it possible to pro- .vide check valves 59 and 61 in circular passageways 7 and 7' that will be effective to control'both fluid streams, inasmuch as each fluid is made to flow through a circular passageway at one time or another. The need for a check valve in annular passageway 9 is thereby avoided .by providing a check valve in passageway 7' which is a duplicate of the check valve in passageway 7.

To carry out this novel concept there is provided a short cylindrical crossover 51 that plugs conduit 3 at a pointnear the burner tip 27. Crossover 51 has threaded connectors 53 and 53', of the same size as conduits 1 and 1', extending axially from the upstream and downstream faces of crossover 51, respectively, to receive the threaded ends of the check valves 59 and 61.

Crossover 51 has a plurality of longitudinal passageways 55 whose axes diverge in the downstream direction and a plurality of similar passageways 57 whose axes converge in the same direction. As shown in FIGURES 1b and 2, the upstream ends of divergent passageways 55 are located Within connector 53 and the downstream ends are located around the outer periphery of connector 53', while the convergent passageways 57 have their upstream ends located around the outer periphery of connector 53 and their downstream ends located within connector 53'.

Check valve 59 connects conduit 1 with connector 53, and check valve 61 connects conduit 1' with connector 53. Thus, fluid flowing through circular passageway 7 passes through check valve 59, connector 53, and divergent passageways 55 into annular passageway 9', while fluid flowing through annular passageway 9 passes through convergent passageways 57, connector 53', and check valve 61 into circular passageway 7', thereby effecting a transposition of the initially flowing circular and annular streams.

Check valves 59 and 61' may be of conventional design and identical construction. Asillustrated, they comprise a ball valve 63 urged in an upstream direction into sealing relationship with an annular valve seat 65 by means of an axially. disposed coil spring 67 that acts under compression between ball valve 63- and the radial legs of a spider 64 having also an axially extending stop-69 to limit downstream movement of ball valve 63 and to serve as a keeper or guide for spring 67.

The check valves are disposed sufliciently close to the downstream or discharge end of the burner to minimize the volume of gas available for explosion or flashback within the burner tubes or passageways downstream of the check valves.

Moreover, the possibility of flashback or explosion from a combustible or explosive fluid mixture in the device downstream of the check valves is minimized by refraining from mixing the fluids in passageways 7 and 9' until they reach a point adjacent the end of the burner. In the embodiment illustrated in FIGURES la-3, mixing takes place in'enlarged'ends 41 of passageways 35; but it will of course be understood that mixing could be conducted still further downstream by causing passageways 35 and 43 to converge toward points at or beyond the end of the burner so that mixing would take place substantially at or even a predetermined distance beyond the burner tip. At the same time, the mixing is very thoroughly carried out by means of the arrangement in which a manifold 49 is provided that communicates with all of passageways 43, the passageways 35 communicating with their supply passageway 7' through conduits 37 that pass through manifold 49. In this connection, itshould also be noted that it could be passageway 7 that communicates with manifold 49 and thus with peripheral passageways 43, and that passageway 9 could communicate with passageways 35 through conduits 37. In this latter case, bafiie 39 could be an annular ring disposed at the discharge end of passageway 9 in sealed relationship with conduits 1 and 3, and conduits 37 would communicate with passageway9 through that annular bafl le rather than passagewty 7 through the circular baflie 39 shown in FIGURE 1b. The important relationship is not which of passageways 7' or 9 communicates with manifold 49, but rather that one of those passageways communicates with manifold 49, the other of those passageways communicating with passageways 35 through conduits 37 that pass through manifold 49.

Mixing of the fluids still farther downstream is illustrated in the further embodiment of burner tip shown in FIGURE 4, comprising an inner conduit 71, an outer conduit 73, and an outermost conduit 75, defining respectively passageways 77, 79 and 81. As before, fluids to be supplied to the combustion zone pass along passageways "77 and 79, while passageway 81 contains a plurality of tubes 83 for the supply of cooling water, as more fully described in connection with the preceding embodiment.

The device of FIGURE 4 includes a burner tip 85 that includes a plurality of nozzles 87 extending thereacross. In this embodiment, however, nozzles 87 are integral with tip 85 and are not set in as in the previous embodiment.

Nozzles 87 extend between those portions of the structure of the device of FIGURE 4 thatcorrespond to shells 29 and 31' in the preceding embodimenuhowever, and cooling fluid spaces 89 are formed between the nozzles 87 through which the cooling fluid passes to cool them and the remainder of tip 85.

Central circular passageway 77 communicates with a plurality of passageways 91 that diverge in a downstream direction from the end of passageway 77. Annular passageway 79 communicates with a plurality of further passageways 93 that also diverge from each other but converge each with an associated passageway 91 of a given nozzle 07. Passageways 91 and 93 thus extend entirely through tip 85. Each nozzle 87 is comprised of a pair of passageways 91 and 93; and hence nozzles 87 also diverge from each other in the downstream direction, that is, to the right as seen in FIGURE 4.

It is important to note, in connection with the embodiment of FIGURE 4, that the axes of passageways 91 and 93 intersect at about the outer contour of tip 85. This assures that the fluids in passageways 92 and 93 do not mix within the burner conduits 71 and 73 but rather mix just as they are about to leave the burner nozzles 87, thus reducing the possibility of backflash or explosion in the burner when neither of the fluids is combustible by itself, that is, in the absence of any other fluid. While initial contact of the fluids is effected a slight distance within the tip of the burner, the velocity of the fluid streams is such that intimate mixing for combustion purposes does not occur until the merging fluid streams leave the nozzle discharge openings.

Still another embodiment of burner and burner tip is shown in FIGURES and 6. In this last embodiment, concentric conduits are provided which are designated 95, 97, 99 and 101 proceeding radially outward from the center. These conduits, alone or with adjacent concentric conduits, define central circular passageway 103 and annular passageways 105, 107 and 109. A burner tip 111 closes the downstream ends of these passageways.

Unlike the preceding embodiments, passageways 103 and 109 are the water passageways, cooling water passing from passageway 103 through passageways 113 and branch passageways 115 in tip 111 to passageway 109, as indicated by the lower arrows on FIGURE 5. Each passageway 113 has a pair of branch passageways 115 that diverge from it and from each other, as best seen in FIGURE 6. There are accordingly more separate passageways that feed passageway 109 than that diverge from passageway 103, so that the cooling water is more evenly distributed about the periphery of outermost passageway 109.

Tip 111 is also provided with passageways 117 and 119 extending therethrough, the former communicating with passageway 105 and the latter with passageway 107. Passageways 117 and 119 are arranged in pairs with each passageway 117 in radial alignment with a passageway 119, in relation to the main axis of the burner, each pair comprised of one each of a passageway 117 and 119 being disposed between the adjacent branch passageways 115 of a pair of passageways 113, as best seen in FIG- URE 6. Each such pair thus provides a nozzle as in the preceding embodiments, with cooling fluid passageways between the nozzles.

The passageways 117 and 119 of each pair converge,

' their axes intersecting a substantial distance downstream beyond the contour of tip 111, as best seen inFIGURE 5. This convergence of the axes of passageways 105 and 107 beyond the end of the burner further assures that while mixing of the streams occurs adjacent the burner tip, mixed combustible fluids will not be in the burner through a burner a combustible mixture.

6 in such quantity as would cause backflash or explosion. The arrangement of passageways 113, 115, 117 and 119 relative to each other is also significant. As will be noted from FIGURE 6, branch passageways 115 diverge in such manner as to leave a radially disposed corridor therebetween when the burner tip is viewed endwise; and passageways 117 and 119 are disposed in these corridors, 'so that not only do branch passageways 115 assure even distribution of cooling water in outermost passageway 109 but also they come as close as is feasible to passageways 117 and 119 and thus provide maximum cooling of the burner tip.' 7

' Thus, in the first place, the present invention provides a crossover that makes possible separate check valves in the central passageways 7 and 7, so that the check valves can be moved close to the discharge end of the burner and thereby minimize the downstream volume in both passageways so as to cut down the volume available for backflash or explosion. In the second place, the danger of backflash or explosion is further avoided by mixing the.

fluids only adjacent or beyond the discharge end of the burner. The resultant possibility of incomplete mixing is avoided, in thecase of FIGURES 1a-3, by a nozzle arrangem nt fed from a manifold in the case of one fluid and a plurality of conduits passing through the manifold in the case of the other fluid. In the case of FIG- URE4, the possibility of incomplete mixing is taken care of by causing the axes of the streams that are to be mixed to intersect at the end of the burner, and in the case of FIGURES 5 and 6, beyond the end of the burner.

Another very important feature of the invention is that cooling fluid passageways are disposed between the nozzles in allot the illustrated embodiments and provide passageways for the movement of cooling fluid transverse ly of the downstream-direction. This feature is particularly significant in the environment of forming mixtures of combustible fluids byteeding through a burner fluids that are combustible when mixed and also by feeding This is because the cooling fluid such as cooling water maintains the nozzles at such a low temperature that backflashjand explosion within the burner are minimized. Therefore, it is an important feature of the present invention that cooling fluid passageways are disposed between nozzles each of which has plural passageways therethrough for different fluids, as distinguished from nozzles that have only a single passageway therethrough for a single fluid that is incombustible in the absence of other fluids.

From a consideration of the foregoing disclosure, it will be obvious that all of the initially recited objects of the present invention have been achieved.

Although the present invention has been described and illustrated in connection with preferred embodiments, it is to be understood that modifications and variations may be resorted to without departing from the spirit of the invention, as those skilled in this art will readily understand. Such modifications and variations are considered to be within the purview and scope of the present invenveying streams of said fluids to said combustion zone; a

plurality of laterally spaced nozzles at the downstream end of said fluid passageways, each nozzle having passageways individual to and in open communication with said I concentric fluid passageways, the discharge ends of said nozzle passageways being so disposed that the separate fluid streams discharging therefrom meet and admix at the end of the nozzle; crossover means near the downstream end of said concentric inner and outer passageways for transposing their respective fluid streams; a check valve within the 'short inner passageway, immediately downstream of said crossover means, to prevent backflow of the one fluid stream; a second checlcvalve within the longer inner passageway, immediately upstream of said crossover means, to prevent backflow of the other fluid stream; means defining lateral passageways for confined flow of cooling fluid between and around said nozzles; and means for supplying cooling fluid to said lateral passageways.

2. Apparatus as in claim 1, in which the separate passageways of each nozzle converge at the downstream end.

3. Apparatus as in claim 2, in which the longitudinal axes of the convergent passageways of each nozzle intersect at the physical end of the nozzle, Whereby the nozzle passageways have side communication with each other and the admixing of the fluid streams is initiated slightly within the tip of the nozzle. t

4. Apparatus as in claim 2, in which the discharge ends of said convergent nozzle passageways are disposed immediately adjacent each other at the physical end of the nozzle, with their projected axes intersecting a slight distance beyond, whereby saidfluids flow as separate streams in passing through the nozzle, and such admixing of the fluid streamsv is initiated immediately upon discharge thereof from the tip of the nozzle. 7

5. Apparatus as in claim 1, including means defining an annular cooling fluid passageway concentrically surrounding said outer fluid passageway,- said annular cooling fluid passageway being in open communication with said lateral passageways between said nozzles for the withdrawal of cooling fluid therefrom, said annular cooling fluid passageway extending backward along said apparatus 'to a discharge location near the inlet ends of said fluid passageways.

6. Apparatus as in claim 5, in which said means for supplying cooling fluid to said lateral passageways between said nozzles comprises a plurality of tubes coextensive with and located within said annular cooling fluid passageway, whereby the supply of fresh cooling fluid passing through said tubes to said nozzles, as well as fluid flowing toward the nozzzles through the outer annular fluid passageway, are in indirect heat exchange relationship with the countercurrently flowing, heated cooling fluid withdrawn from the lateral passageways between said nozzles.

7.. Apparatus for supplying a plurality of fluids to a combustion zone comprising means defining first and second concentric fluid passageways terminating downstream in discharge ends, said passageways being, respectively, of circular and annular cross section throughout the substantial major portion of their length and including crossover means a relatively short distance upstream from said discharge ends effective to transpose the fluid streams, whereby each of said fluids flows as a solid stream of circular cross section before reaching said discharge ends; check valves immediately upstream and downstream of said crossover means in the circular cross section portions of said passageway; a plurality of nozzles at said discharge ends, each nozzle including convergent fluid passageways individual to and in open communication with said discharge ends, said convergent nozzzle passageways having their downstream ends closely positioned so that the fluid streams discharging therefrom meet and admix at the dis, charge end of the nozzle; means defining cooling fluid passageways disposed between the nozzles and extending laterally of the downstream direction; and means for supplying cooling fluid to the cooling fluid passageways.

References Cited by the Examiner UNITED STATES PATENTS 1,660,866 2/28 Dieu 239132 2,755,134 7/56 Eck et al. 239-132 2,794,620 6/57 Arnold et al 239-132 2,807,506 9/57 Gehring 239132 3,065,916 11/62 Kurzinski 239132 3,076,607 2/63 Cordier 239132 EVERETT W. KIRBY, Primary Examiner.

LOUIS J. DEMBO, Examiner.

Claims (1)

1. APPARATUS FOR SUPPLYING A PLURALITY OF FLUIDS TO A COMBUSTION ZONE, COMPRISING: MEANS DEFINING INNER AND OUTER CONCENTRIC FLUID PASSAGEWAYS FOR SEPARATELY CONVEYING STREAMS OF SAID FLUIDS TO SAID COMBUSTION ZONE; A PLURALITY OF LATERALLY SPACED NOZZLES AT THE DOWNSTREAM END OF SAID FLUID PASSAGEWAYS, EACH NOZZLE HAVING PASSAGEWAYS INDIVIDUAL TO AND IN OPEN COMMUNICATION WITH SAID CONCENTRIC FLUID PASSAGEWAYS, THE DISCHARGE ENDS OF SAID NOZZLE PASSAGEWAYS BEING SO DISPOSED THAT THE SEPARATE FLUID STREAMS DISCHARGING THEREFROM MEET AND ADMIX AT THE END OF THE NOZZLE; CROSSOVER MEANS NEAR THE DOWNSTREAM END OF SAID CONCENTRIC INNER AND OUTER PASSAGEWAYS FOR TRANSPOSING THEIR RESPECTIVE FLUID STREAMS; A CHECK VALVE WITHIN THE SHORT INNER PASSAGEWAY, IMMEDIATELY DOWNSTREAM OF SAID CROSSOVER MEANS, TO PREVENT BACKFLOW OF THE ONE FLUID STREAM; A SECOND CHECK VALVE WITHIN THE LONGER INNER PASSAGEWAY, IMMEDIATELY UPSTREAM OF SAID CROSSOVER MEANS, TO PREVENT BACKFLOW OF THE OTHER FLUID STREAM; MEANS DEFINING LATERAL PASSAGEWAYS FOR CONFINED FLOW OF COOLING FLUID BETWEEN AND AROUND SAID NOZZLES AND MEANS FOR SUPPLYING COOLING FLUID TO SAID LATERAL PASSAGEWAYS.

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