US2379217A - Locomotive superheater - Google Patents

Description

3 Sheets-Sheet 1 ET AL J. S. COFFIN. JR.

LOCOMOTIVE SUPERHEATER Filed Dec. '7,

June 26, 1945 Invenforzs'! IIIIIIIIII I UUUuUNUUU 3' I lillllll J1me 1945- J. 5. COFFIN, JR.. ET AL LOCOMOTIVE SUPER'HEATEH June 1945. J. s. COFFIN, JR. ET AL 2,379,217

LOCOMOTIVF; SUPERHEATER Filed Dec. '7, 1940 3 Sheets-Sheet 5 Patented June 26, 1945 LO COMOTIVE SUPERHEATER Joel s. Coffin, Jr., Englewood, N. J., and Christopher A. Schellens, Clifton, Mass., assignors to (3-5 Engineering Company, Englewood, N. J a

corporation of Delaware Application December 7, 1940, Serial No. 369,070

2 Claims.

This invention relates to steam superheaters especially designed for locomotive use.

A locomotive superheater usually has its superheating tubes arranged within the fire tubes of the locomotive boiler and has its saturated and superheated steam headers and associated piping located in the smoke box of the boiler. The smoke box of the boiler contains the draft nozzle, smoke stack, cinder screen and other essential components so that the space available in the smoke box for parts of the superheater and associated piping and the position these parts can occupy is quite restricted. Thus, it has been a fairly general practice, in order to save space,

to form the saturated and superheated steam headers of the superheater as one unitary construction and, because of the weight and bulk of such construction, to secure it rigidily to the boiler at a plurality of points. The various parts of the superheater are subjected to widely different temperatures as the superheated steam and the parts in contact therewith are at a considerably higher temperature than the saturated steam and the parts in contact therewith. These differences in temperature cause the various parts of the superheater to expand different amounts and, in the past, considerable difficulty has been experienced in providing a structure that would not rupture or at least become leaky due to expansion stresses. A leaky superheater is highly undesirable not only because it wastes steam but because the steam combines with the hot furnace gases to cause rapid corrosion of the parts in contact therewith, and also to diminish the draft.

Thus an object of the present invention is to provide a relatively flexible locomotive superheater construction wherein the various parts of the superheater are supported in such manner that they are free to expand and contract without imposing severe stresses on any part f the structure and one containing a minimum number of breakable joints, and under certain conditions no breakable joints.

In particular, the invention contemplates a superheater structurethat is rigidly secured to the boiler structure only at the saturated steam inlet and the superheated, steam outlet, with the superheater parts being so constructed and arranged that they are free to flex or move into positions dependent upon the temperatures of the various parts without imposing undue stresses on the parts. In accomplishing this result not only does attention have to be given to the general layout of the superheater parts, but attention also has to be given to the design and method of construction and method of joining the various parts together in order that stresses due to expansion will be eliminated or minimized and also so that the parts will not be Subjected to initial stress in the securing together of the various parts, and the accomplishment of this result constitutes a further object of the invention.

Another object of the invention is the provision of a superheater wherein the various parts thereof are free for independent expansion and. contraction under influence of the difierent'temperatures to which they are subjected without setting up undue mechanical stresses in the parts.

A yet further object is the provision of a superheater having a saturated steam inlet, a superheated steam outlet and superheater tubes be-' tween the inlet and outlet wherein the structure is connected rigidly to the boiler shell only at the outlets, and all parts of the superheater and the associated piping between the outlets isfree for independent expansion and contraction movements.

Another object of the invention is the provision of a superheater structure wherein the saturated and superheated steam headers and the superheater tubes are independently supported and are secured together while being so supported so that there are no severe mechanical stresses imposed on the parts in the process of securing them together.

A yet further object is generally [to improve the construction and operation of superheaters.

Fig. 1 is a longitudinal sectional elevation through the front end of a locomotive and illustrating the present invention.

Fig. 2 is a transverse section of the locomotive shell taken along line 2-2 of Fig. 1.

Fig. 3 is aplan detail of the superheated steam header and its dual outlet pipes taken along-line 33 of Fig. 1.

Fig. 4 is a section taken along line 4-4 of Fig, 1, and illustrating particularly the manner of securing the outermost tubes of a tube cluster together and supporting the tube cluster slidably upon the inner face of the associated fire tube.

Fig. 5 is a side elevation of the tube spacer of Fig. 4. r

Fig. 6 is a plan detail of a branch header.

Fig. 'l is a sectional view through a tube cluster taken along line 1-1 of Fig. 1.

Fig. 8 is a sectional view of the rear manifold of a tube cluster taken along line 8-8 of Fig. '7.

Fig. 9 is a sectional detail illustrating the manner of joining a superheater tube to the rear manifold.

Fig. is an end view of the front manifold of a tube cluster.

Fig. 11 is a sectional detail of the front manifold taken along line I I-II of Fig. 10.

The locomotive superheater herein illustrated as embodying the present invention is shown in connection with a locomotive boiler having the shell 20, the front tube sheet 22 with the sets of vertically aligned rows of superheater fire tubes or flues 24, and underlying smaller firetubes or lines 26. In front of the front tube sheet the shell encloses the smoke box 28 with the draft nozzle 30, smoke stack 32, and other shown.

Saturated steam is taken from the usual steam dome of the locomotive boiler. Steam passes through a dry pipe 34 and into the combined superheated steam manifold and throttle 36. Said manifold has a steam inlet 30 provided with a flange (Ill that is bolted to the front tube sheet and forms a rigid connection therewith. The manifold has upper and lower cylindrical sections 42 and 44, respectively, that house a sat urated steam throttlevalve having a stem 46 that projects outwardly through the top cover 48 and is operatively connected with throttle operating mechanism 50. The lower housing has welded thereto a pair of horizontal oppositely projecting tubes 52 forming with the lower housing member 44 a saturated steam header. Said tubes have inclined end walls 54 that conform in general to the inclinations of the confronting portions of the boiler shell. Said tubes 52 and the lower housing member are provided with a horizontal line of outlet necks 56 terminating in flanges 5,8 for attachment with saturated steam branch headers 60. The branch headers are provided with flanges 62 at their upper ends and clamping bolts 64 are passed through the flanges 62 and 58 to secure the branch and main headers together. The branch headers and the necks 56 of the main header have interposed ball plates 65 which fit in cooperating sockets at the ends of the branch headers by which the main andbranch headers are connected together insteam' tight relation.

The depending branch headers 60 are located in front of and between the vertical rows of fiues 2 4. .The headers are tapered from end to end and are large at the upper end where they join the main header and are small at the lower end. The branch headers are free from rigid connection with any part of the locomotive structure except with the main header and are free to flex or bend transversely of their length. Each of the branch headers is providedwith a vertical series accessories notof tubular necks 66 which extend horizontally from the vertical line of the header and rearwardl y or toward the front tube sheet for connection with the superheater tube clusters.

The superheated steam header 68 comprises a l nd ic l P or tu e 0. re erably la e t the cross-section of the saturated steam header, and extended horizontally transversely of the boiler shell below the saturated steam main and branchheaders and forwardly thereof and parallel with the front tube sheet. The superheated steam header is provided with a plurality of upstanding inlet necks !2 terminating in outstanding flanges 14 and is connected with a plurality of vertically upstanding superheated steam branch headers 16. the branch'headers at the lower .ends I having attaching flanges l8 and clamped to the main header by bolts 80 passing through the flanges I8 and I4, with intervening ball plates 19 seated in sockets in the ends of the necks 12 of the main superheated steam header. The superheated steam branch headers are preferably larger in cross-section than the saturated steam branch headers because of the greater volume of the superheated steam. The superheated steam branch headers 16 are disposed in vertical line with the axes of the vertical rows of ilues 24 and are disposed in front of and between the saturated steam headers. The branch headers l6 taper upwardly from the superheated steam header so that the branch headers are large at their connection with the main superheated steam header and are small at their upper ends. The tapers of the saturated and superheated steam branch headers thus are complemental and the width of the gas passage between the branch headers is approximately constant from top to bottom of the branch headers.

The superheated steam branch headers I5 are rigidly connected only with the main superheated steam header and hence are free to flex or bend transversely of their length. The branch headers 16 are provided with a vertical series of Short necks 02 horizontally extended rearwardly in the axial line of the associated fiues 24 and are adapted. for connection with the associated superheater tube cluster. The superheated main header 10, in the form illustrated in Figs. 1 and 3, comprises a tube having closed ends 84 that are sloped downwardly and inwardly to correspond generally with the slope of the confronting regions of the boiler shell. The header I0 is provided with a pair of forwardly horizontally extending outlet necks 06 located near the ends of the header and connected preferably by welding to superheated steam pipes 88 which are extended forwardly and slightly downwardly parallel with each other on opposite sides of the draft nozzle 30 and thence bend outwardly and are provided with flanges 90 which are fixed rigidly to the exterior steam connections 52 leading to the locomotive cylinders. The superheated steam header and superheater branch headers thus are connected rigidly to the locomotive only at the cylinders. The pipes 88 are capable of expansion and flexion upon increase of temperature without imposing undue stresses on the superheater parts.

The fiues 24 contain superheater tube clusters which are identical in construction. Each tube cluster, see especially Figs. 1 and 4, consists of a plurality of outer superheater tubes 04, herein four tubes, and a common central tube 06. The number of. outer tubes 94 can be varied to suit particular conditions. The tubes 94 open into and lead from a front manifold 08 and are connected to and open into a rear manifold I00.

The central tube 95 opens into the rear manifold and slidably passes through the front manifold 00.

The rear manifold I00, see Figs. 7 and 8, is generally conical and has a plurality of equiangularly spaced bosses I02, herein four bosses which at the forward end surround a central annular neck I04 and have themselves annular necks I06, the bosses converging at the rear end of the manifold. Each boss has a steam passage I00 that is inclinedtowards the central axis of the manifold and opens into a central co-axlal passage I I0 that is in communication with the central'neck I04. The ends of the superheater tubes 94 are abutted against the ends of the necks I06 and are electrically welded thereto by current passing through the contacting region,

thereby fusing the ends of the tubes and the necks together, the weld being completed .by moving the tubes axially in the direction of the necks in the usual manner, which upsets the fused metal and forms annular beads II2 of metal around the bonded regions, see Fig. 9, both outside and inside the tube. The passages I08 are purposely made smaller than the inside diameter of the tubes 94 to increase the velocity of steam flow in the manifold I and to promote turbulence therein so as to promote transfer of heat between the manifold and the steam and to keep the manifold cool. This is desirable since the manifold is relatively near the locomotive fire box and is subjected to the hottest gases. The manifold is conical to prevent collection of cinders thereon. The common return tube 96 is similarly resistance welded-t0 the neck I04. By having the passages I08 small in diameter, as described, the manfold I02 can be made from a forging, with the gained advantage of strength and denseness, since the passages I08 can be drilled out of the solid metal of the forging and can be straight and clear the inner wall of the neck I06 which should conform closely to the inner diameter of the associated tube 94.

The front manifold 98 is composed of two similar rear and front sections H4, H6, respectively. The manifold is generally cylindrical and has a laterally projecting ear II'I which is generally in line with the lower pair of tubes 94. The rear manifold section H4 is provided with openings II8 therethrough and the front end parts of the tubes 94 are located therein and are rolled into steam tight engagement with the walls of the openings, the interior of the manifold being provided with a recess or chamber I20 to accommodate the outstanding flanges of the tubes formed by the rolling process and to allow steam flow between the ear and the tubes. The rolling of the tubes into steam tight engagement with the front manifold is preferred for a number of reasons, one of which is that the electrical welding of the tubes to the rear manifold shortens the length of the tubes a somewhat variable amount which is not objectionable when the 60 through a sleeve I38. The sleeve I38 is ap plied over the confronting ends of both the necks I34 and 66 and is arc welded toboth necks as indicated at-I40. The sleeve I38 is of sufiicient length to overlap both necks regardless of reasonable variations in the distance between their confronting ends. The end of the return tube 96 is similarly secured to the associated neck 82 of the superheated steam branch header I6 by a similar sleeve I42 applied in a similar manner.

The outer tubes 94 of a superheater clusterare connected together at spaced intervals and supported-in parallel lines by tubular spacer members I44 which have outstanding ribs I46 paralleling the tubes and'welded thereto. The spacer member has an internal tubular passage I48 through which the central tube 96 is freely axially movable and by which the tube is supported. The

tubes are rolled into the front manifold but may i be objectionable if the tubes are secured to the manifold in some other manner. The front section I I6 of the manifold is provided with threaded openings I22 aligned with the tubes and normally closed by screw-threaded plugs I24 which can be removed at any time for purposes of removing scale from the interior of the tubes 94 or otherwise cleaning the interiors thereof. The primary purpose of the openings however is to allow a rolling tool to pass into the manifold to roll the tubes in the rear section of the manifold. The two manifold sections are provided with abutting ribs I26, I28 which surround a passage I30 through which the central return tube 96 is freely extended. The two sections may be secured together by arc welding, as indicated at I32, before rolling the tubes, and arc welding material may also bond together the necks I26, I28. It is preferred, however, to sweat the sections together by grinding the confronting surfaces accurately flat and depositing a very thin layer of copper therebetween and fusing the copper in an inert or hydrogen atmosphere.

An inlet tube I34 is welded to the ear of the outer manifold section II6 about the inlet opening I36 therethrough. The inlet tube I34 of a tube cluster is connected to the associated aligned neck 66 of the branch saturated steam header tube cluster is supported within its fiue'24 by ribs I50 which are welded to the outer faces of the lowermost two tubes at spaced intervals and preferably: at the regions of the spacer members I44 and bear loosely upon the inner surface of the flue. The spacer member is formed conveniently of as many complemental arcuate members or stampings as there are other tubes 94, herein four stampings having. outstanding longitudinal flanges flash-welded together to form a unitary structure and provide the aforesaid ribs I46.

This manner of supporting the tubes permits the free and unobstructed flow of gas between the tubes so that cinders have no opportunity to collect or to be deflected against either the superheater tubes or the flue wall. The passage around the tubes is also freeso that a flue blower or bar.

taching sleeves I38 and I42 placed over the confronting ends thereof and the sleeveswelded in place-without the application of any mechanical stresses to the parts. The parts also are free to expand without restraintwhen subjected to the steam and gas temperatures.

The connection between the front 'manifold of an uppermost tube cluster with a saturated steam branch header is near the largestdiameter thereof at a point where the branch header is the least capable of flexing. The superheater tubes, however, are free to expand axially and the central tube 96 is free to move axially within the front manifold. The central tube of the uppermost header is connected to the top part of the cluster. With an intermediate tube cluster the I excess expansion of the tubes is taken care of by the flexing of both saturated and superheated steam branch headers. Thus free expansion of the various parts of the superheater structure is provided for. The collection of superheater tube 3 clusters also forms a rigid mechanical interconnection between the two main steam headers and,

in effect, ties them together betweenthe points where they are rigid with the front tube sheet and cylinders, l 1

In installing the superheater structure, the main saturated and superheated steam headers are first properly installed. The tube clusters are placed in the lines. A saturated steam branch header is then bolted to the main header temporarily. The attaching sleeves are placed over the necks of the branch header and over the inlet necks of the tube clusters of a vertical row of fire tubes. The tube clusters are then pulled forward to the proper position and the sleeves are tack welded to both the branch manifold and; the tube clusters. The corresponding superheated steam branch header is then bolted to the main header with a thinshim temporarily therebetween with sleeves over the necks of the branch header and the outlet tubes of the vertical row of tube clusters. The second set of sleeves is then tack welded in place. The branch headers are then unbolted and the two headers with the vertical group of tube clusters is then pushed backwardly out of the way and the assembly is progressed in a similar manner throughout the entire unit. The first vertical row is then pulled forwardly to an accessible place and the sleeves are then welded permanently in, position, this process being repeated for all the rows. The final step is to bolt the branch headers to the main headers securely. With this construction, any vertical row of tube clusters with their associated branch headers can be removed by disconnecting them from the main headers. A faulty tube cluster can be cut out and replaced by a serviceable cluster which is welded to the branch manifold.

The superheater as thus described is essentially self-draining. It will be noted that the inlet neck I34 of the front manifold of a tube cluster is in line with the lowermost two outer tubes 94 of the cluster. The outlet pipes 88 of the main super, heated steam header also open into the bottom of theheader and drain to the locomotive cylinders. Thus when condensation occurs within the superheater structure any water that forms in an uppertube cluster flows out of the inlet neck I34 into the saturated steam branch header and flows into the lowermost tube cluster. Water in the lowermost tube cluster flows through the central pipe 96 and into the superheated steam branch header and thence into the main header and outwardly through the cylinders. Thus it is only possible for water to collect in the lowermost two tubes of the lowermost tube cluster. The amount of water that can be contained in these two tubes is relatively slight and will be dislodged on the first few steam bubbles that form when steam is being made and the water blown into the cylinders. Thus the possibility of movement of the locomotive occurring through formation of steam from any condensate that may collect in the present superheater structure is quite remote. As a consequence, it is practicable to throttle the saturated steam by the throttle 46 in the saturated steam header or by the usual throttle in the steam dome of the locomotive.

We claim:

1, In a locomotive, upper and lower fixed supports spaced one forwardly of the other, and a superheater structure suspended between said supports comprising a saturated steam pipe supported at the upper support and having a part projecting forwardly of the upper support and not otherwise rigidly supported, I a saturated steam main header depending from the projecting part of said pipe, a superheated steam pipe supported at the lower support and having a part projecting generally horizontally rearwardly of the lower support and not otherwise rigidly supported, and flexible under expansion stresses, a super-; heated steam main header fixed to and upstanding from the end of said projecting part of said superheated steam pipe, the projecting parts of said pipes being capable of flexure upon expansion of said main headers, depending and upstanding branch headers carried by and fixed to said main headers free from rigid interconnection with each other and capable of lateral flexure upon expansional forces.

2. A locomotive superheating tube cluster for extending within and for being supported by and in spaced relation to the walls of a boiler flue, said cluster comprising a central tube and a plurality of outer tubes disposed in parallelism with and around the central tube, and spacing means intermediate the ends of the tubes comprising a tubular member loosely surrounding the central tube and rigidly connected to each outer tube only at their sides toward the central tube. and projections on at least two adjacent outer tubes on their sides remote from the central tube, for engaging a flue wall.

JOEL S. COFFIN, JR.

CHRISTOPHER. A. SCHELLENS.

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