US2354222A - Fluid heat exchange installation - Google Patents

Description

y 1944- R. SHELLENBERGER FLUID HEAT EXCHANGE INSTALLATION 5 Sheets-Sheet 1 Filed Dec. 4, 1941 Fig. 7

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FLUID HEAT EXCHANGE INSTALLATTON I Filed-Dec. 4, 1941 3 Sheets-Sheet 3 INVENTOR. R 0/ Fe Z7e//enberger Attorney Patented July 25, 1944 FLUID HEAT EXCHANGE INSTALLATION Rolfe Shellenberger, West'ileld, N. 1., assignor to The Babcock 8; Wilcox Company, Newark, N. 1., a corporation of New Jersey Application December 4, 1941, Serial No. 421,565

18 Claims.-

This invention relates to fluid heat exchange installations, and more particularly to a tubeto-tube wall or baiile construction for a furnace,

or for a gas pass The invention maybe considered as exemplified by a plurality of steam heating tubes closely arranged and disposed in row alignment so as to define a furnace or gas pass wall.

One object of the invention is to provide means whereby the wall tubeswill be maintained in their wall formation with a minimum of uncooled metallic supports. 1

Another object of the invention is to accomplish the desired results and at the same time provide a tiibe-to-tube wall which includes adequately cooled all-metal closures, .or gas seals, supported by the successive tubes.

The invention is particularly adapted for radiantheaters of the wall tube type when employed as walls separating series connected gas passes. When such heaters are employed as steam superheatersor'reheaters the high temperatures to which the tubes are subiected'are apt to cause conditions of unbalance. Such conditions may arise when steam flow through the tubes is reduced while" exposed portions of the tubes arestill receiving abnormal amounts of heat from iurnacegases. Such conditions are apt to cause distortion of the tubes or such bending 01 some of the timesrelative to adjacent tubes that gas leakage develops in the wall formed by the tubes. Such results are to be particularly avoided in a time-to-tube wall construtcion consisting of metallic elements only and so disposed in a. boiler setting that the wall divides two gas'passes arranged in series. In this arrangement, the wall is subiect to a draft diflerential from one side to the otherandthis has a tendency to cause a gas fiow through" the inter-tube spaces or gaps. Such gas how, or gas leakage, when a, tube-totube wall isemployed in a steam generating installationpwould not only cause the heat ap-- piication-to the individual tubesto be abnormal,

but it would involve such by-passing of the gasesthat the thermal performance of the convection surface of the installation wouldbe undesirably affected, and would result in a'decrease in efilciency of the imit. It is a further object of the invention to provide a specific tube wall construction which will substantially eliminate such undesirable eflects;

The invention will be described with reference to the accompanying drawings, and further objects of the invention will appear as the descrip-' tion W48- part of the In the drawings: Fig\ 1 is a vertical section of a steam generating installation in which an embodiment of the I Fig. 6 is a view in the. nature of a side elevation of the wall indicated inPlg. 2;

Fig. 7' is a detail .view showing on an enlarged scale the manner in which the steam heater tubes are secured to the tie-bars;

Fig. 8 is a. horizontal section on of Fi 7;

Fig. 9 is a detail view indicating a'wall construction in which round rod sealing elements are employed;

Fig. 10. is a detail view illustrating the manner the line i-l in which the reheater wall tubes are supported;

and

Fig. 11 is a partial rear elevation of a tube-totube wall such as indicated in'Flg. 9. I

- The illustrative wall construction is employed as part ota reheater, and it separates the gas pass ll of a convection section I! from. the second open pass ll of thesteam generator shown in Fig. 1. This installation includes a furnace ll,

the walls of which are defined by'steam generating tubes connected to the upper and lower drums II and II. Other steam generating tubes similarlyconnected' to these drmns define the walls 21 and lbof the first open passiil. This gas pass-receives iurnace gases it its lower end from the combustion chamber If and-discharges them into the second open a at the upper installation. The furnace is fired by one or more pulverized fuel burners 80.

Steam separated from the water in the dllm ll passes through the tubular connections I! to the inlet header ll of a convection superheater which includes the tubular sections "-8. disposedacrossthepathoftheturnace gasesinths gaspass ll.

From the outlet header f oi the first superheatensteam passes through a pipe I! to the inlet header ll of a second superheater and thencethrough the superheater tubes 46 to the outlet header 4|. From the latter the steam passes to a turbine or other unit.

The illustrative wall between the open pass ll to a tie-bar or channel 50 by means of I through openings 66 in the they may contact the web 16 of shown as the bars 4 sides of the tubes and the convection section i2 is formed by re-' heater tubes 50 (also 50', 50", and 50") connectmay be provided so that when the tubes are cold the free edges of the bars may-be slightly spaced from the adjacent tubes, but under normal operating temperatures, the preferred condition is that they contact those tubes...

In the reheater wall zone 3" (next adjacent the zone A)' similar sealing members 9lll2 are welded to the left hand sides of the tubes, and

- they similarly extend across theinter-tube spaces heated to high temperatures, the tubes may expand, and at least a substantial part of that expansion is taken up in the inter-tube spaces thereby minimizing any accumulative increase in' the transverse dimension of the wall defined by the tubes. For this reason, the proper seals between the-end tubes of the wall and the outside walls of the casing of the steam generating installation may be efiectively maintained.

Theillustrative tubeto-tube wall thus presents.

a metallic face for radiant heat absorption, and yet, in itself, provides for the normal change in the tube diameter due to change in temperature. At the same time, the expansion spaces are arranged for sealing by accumulation of dust or slag which would tend to flow through the spaces (under starting-up conditions) on account of the draft difierential between the opposite sides of the wall. a

When the illustrative wall is employed as a part of a steam heater, it may operate at high temperatures, and theexpansion changes are of con-'- siderable moment, although the steam pressure may be relatively low. Such expansion changes .are particularly difflcult to handle in an arrangement where the tubes form a gas tight wall. The

"temperature of the steam passing through the ,tubes may be as high as 1000 F.', and there may be difierential temperatures between the tubes of the order of 100 F. Such temperatures, and high pressure conditions, may be accompanied by a draft diiferential of the order of 5" of water between the two sides of the wall.

so that theymay contact the adjacent tubes rearwardly of the plane of their centerlines. With this. arrangement it will be observed that any force tending to move the tube 50'! (Fig. 5) in the direction of the arrow, out of the plane of the -wall, will be resisted by pressure on the tube 5."

by the sealing members SO -82. secured to the adjoining tube 50'. Any tendency of the tubes 50" to move in an opposite direction is restrained by pressure of the members 80-82 on the adjoining tubes 50'. Similar eifects involving the remaining tubes and' sealing members maintain all of the tubes in their operative positions.

The bars (or sealing members Ill-l2 and 9ll92) extend obliquely with respect to the plane of .the wall, and there is-=a clearance between the face of each bar and the adjacent tube, in the cold position. Yet the gap in the direction of the I centerline of the row of tubes is greater due to the The difiiculties of maintaining desirable operative conditions over awide temperature range are also increased when the tubes are of relatively small diameter and of increased flexibility and fairly low wall thickness.

Alternatetubes such as and 50" are secured lugs such as li2 and GI welded to the tubes. The lugs extend vided with. vertically adapted to register with extending openings GI slots [0 inthe flanges of the tie-bar 60. When the tubes are assembled in operative relation to the tie-bar, locking rings 12 are positioned upon the Fig. 6) ,and locking pins" are inserted through the openings 68 to hold the rings in place so that the channel 60 and prevent any substantial movement 01' the tubes away from the tie-bar.

Intermediatetubes such as the tubes 50' of the reheater are prevented from having any sub-. stantial movement out of the plane of thewall lateral sealing members welded to the tubes. In the wall zone A," such sealing members are 80-82welded to the right hand in the' manner particularly indicated in Figs. 3 and 4. These bars extend from the attached tubes to positions wherein they may contact the adjacent tubes rearwardly of the plane of their centerlines.

angularity. Thus, provision is made for the individual expansion of the tubes or for irregularity in the outside dimensions of the tubes. N

The gas flow gap from the lace oi? the tubes (when the wall is cold) tapers, and this is conducive to thequick accumulation of dust and/or slag to effect a proper sealing und r operative .high temperature conditions, and it tends to prevent blocking of the diametrlcal expansion of the tube into the inter-tube spaces by slag or dust accumulations.

The angularity of each oi the sealing members with respect to the external wall of the tubes to which it is secured also provides an advantageous groove for. the deposition oi',-'weld metal.

This groove'may be referred to as thin, and it is this characteristic-which reduces the amount of weld metal to be deposited, and, what is more important, reduces the local stresses in the tubeportant when the tube walls are thin.

The bars or sealing members "-82 and 80-" are also so positioned that they are eilectively shielded, from radiant heatin the portions of the bars most remote'i'rom the tubes to which they are welded. Each bar is also in close heat tie-bar and are prolugs 64 '(as indicated in edge.

transfer relationship to the tube adjacent its free Both of these conditions. tend to keep the sealing members at such relatively low temperatures that there will be no deterioration oi the metal. Stresses on the tube .walls over the areas of detachment of the bars are also limited.

The embodiment of the invention illustrated in Figs. 9 and 11 includes round rod sections l I l -I I3 between adjacent .tubes. They are secured in alternation (as indicated by the welds 5- I I8 in Fig. 1 l) to adjacent tubesand are otherwise arranged in a manner similar to the above described sealing members. However, the'round looped rods I02, the ends ill of which-are bent when the tubes are rod sections provide for improved fairing up" between the tubes and they also provide for an added reduction in the amount of weld metal necessary to secure them to the tubes.

The reheater wall is associated with the upright portions llil of the superhe'ater tubes by into vertical positions so as to extend through openings I06 in the flanges oi." the tie-bar II.

A similar reheater wall and tie-bar construction may be employed at Ill (see Fig. l) where the superheater tube portions between the superheater sections 31 and 38 are located.

The tubes (ll, ill, 50", etc) of the reheater wall may be supported from the header 34 in the manner indicated in Fig. of the drawings. This disclosure includes the elements III, I22, and I24 or a hanger by which the tube II is suspended. Reheater tubes adjoining the tube thus suspended may be eifectively supported by the sealing members between these tubes. By reason of the particular construction and arrangement of these members they may by their end bearings provide adequate dead weight sup-.

ports f or some of the reheater tubes without undesirable effects upon their other functions. Thus, not only are original installation costs reduced by a decrease in the number of hangers necessary to support the wall, but also, better maintenance characteristics are afforded.

Although the invention has been described with reference to the details of the particular embodimerits shown in the drawings, it is to be appreciated that the invention is not limited to all of these details. The invention is, rather, to be regarded as of a scope commensurate with the scope of the subjoined claims.

What is claimed is:

1. In a fluid heat exchange installation, closely arranged fluid conducting tubes arranged to present a wall exposed to the heat of furnace gases, restraining means limiting separation of the tubes in the plane of the wall, and a plurality of metallic elements disposed within channels substantially defined by adjacent tubes and substantially closing off the inter-tube spaces laterally of the plane of the tube center1lnes,the elements within each of said channels being arranged in end-to-end relationship with each element secured to one tube only and successive elements secured to different tubes.

2. In fluid heat exchange apparatus, a row of closely spaced parallel tubes connected into a fluid system and arranged to define a wall or other boundary of a furnace gas space, the facing surfaces of adjoining tubes substantially defining V-shaped channels. on opposite sides of a 'Dlane c'ommon to the tube centerlines, supporting means for at least some of the tubes, and metallic members substantially closing the intertube spaces exteriorly of said plane and maintaining the tubes in their wall forming arrangement, said members alternatingeither singly or in g oups as to their securement to one or the other of two adjacent tubes and extending from their supporting tube into close proximity to an the adjoining and facing opposing surface of tube, successive members longitudinally of the channels having end-to-end contact whereby rel-' ative longitudinal movements of adjoining tubesare limited. I

3. In combination, a row of closely adjacent tubes connectedinto a fluid system and arranged to define a wall for a furnace gas space, Pa s of the facing surfaces of adjoining tubes substantially defining V-shaped channels onopposite sides of a plane defined by the tube centerlines, and short metallic members secured in rows longitudinally of the tubes and disposed externally of said plane with at least their major portions within the channels .opening away from the furnace gas spacesdtcessive members-within any only with their free opposite surfaces disposed in close proximity to the adjoining tuben 1 '4. In fluid heat exchange apparatus, .closely spaced tubes projected into a fluid system and arranged so as to define a wall of a furnace gas space, transverse tie-bars on one side of the wall, means for securing some of the wall tubes to the tie-bars, and rows of metallic sealing strips or bars disposed in longitudinal arrangement between adjacent tubes, some of said strips or bars between the same adjacent tubes being welded to the same tube and disposed so as to almost contact the adjacent tubes beyond the plane of their centerlines, others of the bars or strips between the same tubes being welded to the other of the tubes and disposed so as to be similarly closely related to the first tube, said bars or strips being set back rearwardly from the plane of the centerlines of the tubes.

5. In fluid heat exchange apparatus, a plurality of closely spaced tubes disposed in wall formation one of the latter channels alternating with re- I spect to their securement individually to one tube and exposed on one side to the heat of furnace gases, and spaced metallic projections secured to the facing. sides of adjoining tubes to prevent movement of the tubes from their wall formation and to substantially close the spaces between the tubes, the spaced projections on each of said adjoining tubes extending into the-spaces between successive projections from the other of said tubes, said projections also extending from their supporting tubes into positions wherein they will engage the next' tube to prevent excessive relative movement of the tubes in directions normal to the race of the 'wall.

- 6. In fluid heat exchange apparatus, a plurality of closely spaced tubes disposed in wall formation and exposed on one side to the heat of furnace gases. and metallic strips secured at longitudinally spaced positions to the facing sides of adjoining tubes and substantially closing the inter-tube spaces, said strips being also disposed rearwardly of the centerlines of the tubes for maintaining the tubes insthe'ir wall formation, the spaced strips on each of two adjoining tubes extending transversely beyond the inter-tube space and into the spaces between successive strips on the other of said tubes.

'7. In a fluid heat exchange apparatus, a gas pass wall including closely adjacent tubes connected into a fluid system, and metallic closure members extending longitudinally of the tubes the tubes in their wall arrangement.

8. In fluid heat exchange apparatus, a tubeto-tube wall connected into a fluid system and separating two series connected heating zones ,between which there is a pressure differential,

the successive tubes of the wall having a minimum spacing only slightly more than the diametrical expansion of a tube over the tempera? ture range of the apparatus, metallic space closure members secured to the quadrants of the tubes remote from the first of said zones and extending across the intertube spaces, some of the closure members iii each intertube space being secured to one tube and extending to a position 4 wherein they'are close to the adjoining tube, and others otxthe closure members in the same ranged relative to the adjoining tubes, said members substantially closing the spaces between the tubes and forming outwardly tapering ash or slag receiving pockets with adjacent surfaces of the rear quadrants of the tubes.

9. In fluid .heat exchange apparatus, tubes arranged to define a wall subject on one side to furnace gases, the tubes having a wall spacing only slightly greater than their diametrical expansion, two sets of metallic closure members between each pair, of successive tubes, said members being secured to the rear quadrants of the tubes, one 'set of, said members being secured onlyto one of said tubes while the members of the other set are secured only to the adjoining tube, each of said members extending from its upporting tube into close proximity to the opposing surface of the adjacent tube, a tie-bar extending across the tube defined wall, means securing at least some of the tubes to the tie-bar, and means connecting the tubes into a fluid system.

10. In fluid heat exchange apparatus, a row of I tubes closely spaced in the plane or zone common to their centerlines and arranged to define a wall exposed on one side to'the heat of furnace gases, the spacing of the tubes in the row being such that the tube metal constitutes almost the entire fumace gas face of the wallat operating temperatures, a wall support, means for securing some of the tubes to the support, and separate metallic sealing members secured to all of the tubes rearwardly of said plane or zone and maintaining the remaining tubes in wall arrangement, each tube having the sealing members extendin from opposite sides thereof with some of said membersspaced longitudinally of the tube so that they afford spaces for the disposal therein of similar members secured to a succeeding tube. a r

- 11. In a superheater or reheater, a row of wall tubes subject externally to the heat of furnace gases, means connecting the inlet ends of the tubes .to a source of steam, rows of closure members secured to the facing sides of adjacent tubes ,and disposed back of the common plane of the in; tertube space being reversely secured and arfining a wall exposed on one side to the heat offurnace gases, the tubes being closely spaced with surfaces of adjacent tubes substantially defining V-shaped channels on opposite sides of a plane determined by the tube centerlines, means connecting th tubes into a fluid system, tie-bar means to which some of the tubes are secured, and co-acting closing members disposed in the channels between the tie-bar means and said plane, some of the members in any one hannel being secured to one tube and extendl g across the channel with their free edges in proximity to the surface of the adjoining tube while the remaining reversely arranged with respect to their relationship to the adjoining tubes, said members co-acting with th adjoining tubes to form ash receiving pockets,

with their opposite sides converging toward the furnace gas face of the wall.

14. In fluid heat'exchange apparatus, a row of tubes closely spaced in a plane or zone common to their centerlines and arranged to deflne a wall exposed on one side to the heat of furnace gases, the spacing of the tubes in the row being such that the tube metal constitutes more than 95%- of the entire furnace gas operating temperatures, a wall support, means for securing some of the tubes to the support, and separate metallic sealing bars secured to all of the tubes rearwardly of said plane or zone and coacting with the support to maintain the remaining tubes in wall arrangement, each tube having of each tube and secured on opposite sides thereof tube centerlines relative to the furnace gases,

- some of said members being secured to one of each pair of-adjacent tubes while others of the members,are secured to the other tube of each pair, all of said members being disposed longitudinally of the tubes and extending ,from their supporting tube into a position where they. may

contact the adjacent tube to prevent abnormal movement of the tubes from their wall forming relationship. I

12. In a fluid heating installation, tubes defining a wall exposed on one side to the heat of furnace gases, the tubes being closely spaced with surfaces of adjacent tubes substantiallydeflning V-shaped channels on opposite sides: of aplane'- determined by .the tube centerlines, means connectingthe tubes into a fluid system, and coacting space closing and tube interlocking members disposed in the channels remote from-the furnace gas face of the wall, some of the members.

in any one channel being secured to one tube'and extending across the channel with their free edges ,in proximity to the surface of the. adjoining tube while the remaining members in the same channel are reversely arranged with respect to their relationship to the adjoining tubes.

13. In a fluid heating installation, tubes de and extending into close proximity to adjoining tubes, the sealing elements extending from adjacent tubes being so related that the sealing elements from any single tube extend into the spaces between successive sealing elements secured to adjoiningtubes, said sealing elements being oifsct from the plane of the centerlines of said tubes and, extending from the tubes a distance greater than the tube-to-tube spacing. 4

16. In a fluid heating installation, tubes deflning a wall exposed to the heat of furnace gases, the tubes being closely spaced with surfaces of adjacent tubes,substantially defining .V-shaped channels on oppbsite sides of a plane determined by and common to the tube centcrlines, means connecting the tubes into a fluid system, tie-bar.

means to which some of the tubes are secured,

and co-acting space closing and tube inter-locking members disposed in the channels and between two parallel planes tangent to the tubes toward opposite sides of the wall and parallel to said tube center-line plane, each of said interlocking members being directly and rigidly secured,to one tube only and arranged so as topermit adjacent tubes tohave limited relative movements while maintaining the tubes not secured to the tie bar means in substantial wall forming relation to.

those tubes which are so secured.

17. In a steam generator having an open pass disposed between the furnace and a convection section, means including steam heater tubes in a faceof the wall atsubstantially tube-to-tube wall arrangement for separating said open pass from. the convection D members carried by the steam heater tubes and substantially sealing the wall between the convection pass and the open pass without the use of non-metallic refractory in that wall, said metallic members maintaining the integrity of the wall without rigidly securing adjacent tubes to each other.

18. In a tubular wall construction for fluid heat exchange apparatus, a plurality of closely spaced tubes connected into a fluid system and disposed so as to define a wall exposed to heat,

and tube aligning and space closing metallic means for suspending some of the said tubes, and intertube sealing elements spaced longitudinally of each tube and secured on oppositesides thereof so as to extend into close proximity to adjoining tubes, the sealing elements extending from adjacent tubes being arranged for end to end contact and so related that. the sealing elements from any single tube extend into spaces between successive sealing elements secured to adjoining tubes, said arrangement of sealing elements being thus adapted to act as dead weight supports for tubes adjacent a suspended tube.

ROLFE SHELLENBE'RGER.

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