US2962007A

US2962007A - Long span tubular heat exchange apparatus

Info

Publication number: US2962007A
Application number: US669474A
Authority: US
Inventors: Paul H Koch
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1957-07-02
Filing date: 1957-07-02
Publication date: 1960-11-29
Anticipated expiration: 1977-11-29

Description

NOV. 29, 1960 p, KOCH 2,962,007

LONG SPAN TUBULAR HEAT EXCHANGE APPARATUS Filed July 2, 1957 4 Sheets-Sheet 1 45 23 20 a 17 fl/\ I 2 I 22 15 v 40B 0 29 FIG] 40A 1 INVENTOR.

Paul H. Koch ATTORNEY NOV. 29, 1960 H KQCH 2,962,007

LONG SPAN TUBULAR HEAT EXCHANGE APPARATUS ATTORNEY NOV. 29, 1960 p KOCH 2,962,007

' LONG SPAN TUBULAR HEAT EXCHANGE APPARATUS Filed July 2, 1957 4 S heets-Sheet a FIG.5

INVENTOR. Paul H. Koch,

ATTORNEY Nov. 29, 1960 P.- H. KOCH 2,962,007

I LONG SPAN TUBULAR HEAT EXCHANGE APPARATUS Filed. July 2, 1957 4 Sheets-Sheet 4 INVENTOR.

Pa u I H. K och BY TO R N EY LONG SPAN TUBULAR HEAT EXCHANGE APPARATUS Filed July 2, 1957, Ser. No. 669,474

6 Claims. (Cl. 122510) This invention relates in general to fluid heat exchange apparatus, and more particularly to the arrangement and construction of a bank of spaced tubes or tubular sections spanning a gas pass of a large dimension in the direction of the length of the tubular section with the supports positioned at the opposite ends thereof.

The invention involves a long span tube bank with such a particular arrangement and construction that the tubular sections inclusive of supports comprising the bank of tubes will be maintained in their operative positions transversely of gas flow without requiring the use of tube bank supports arranged in the gas flow path intermediate the ends of the tube bank, and tending to cause the collection of solid materials such as slag and dust particles thereon, which, in turn, promote corrosion of the metal of the supports and obstruct gas flow.

Further, and more particular, the invention relates to the construction and support of a bank of long span tubular steam superheater platen elements associated with an upright heating gas downfiow pass of a high pressure steam generator.

In accordance with the invention, the superheater bank is formed by an assembly of platen elements, each comprising multiple looped nested tubes in vertical alignment with a distinctive arrangement of structural intertube connectors and spacers cooperating with vertically adjacent tube lengths having a parallel fluid flow therein to form a plurality of multiple tube length beam sections. Optimum deflections of horizontal tube lengths between end support brackets, which are carried by upright gas pass wall tubes and arranged in locations minimizing overheating and corrosion attack by heating gases, are thereby obtained. Rigid connections positioned between the tube lengths of each beam section of the superposed adjacent parallel fluid flow paths are spaced along the elongated tubes to increase the stiffness and minimize deflection of the beam section, while intertube load carrying supports permittting limited relative axial movement are positioned between adjacent Vertically aligned tube lengths of adjacent beam sections. Thus the weight of a group of serially connected multiple loop sections arranged in vertical alignment is carried to a pair of support brackets associated with the opposite ends of the lowermost beam section of the group. As the vertically spaced horizontal rigidly connected tube lengths or legs of each beam section are in parallelism as regards fluid flow, and are subjected to substantially similar heating gas conditions, the rigid welded connections will be'between tubes having substantially the same metal temperatures;

More specifically in each platen, one end of the upper tube length of the pair forming the uppermost beam section is connected by a relatively large radius return bend to the lower tube length of the pair forming the next subjacent beam section, while the corresponding end of the other tube of the pair of tube lengths rigidly connected together to form the first beam section, is connected by a relatively small radius return bend to the upper tube length of the pair forming the next subjacent States Patent beam section. While the superjacent beam sections are thus supported one from the other at one end by the return bend connections, a spacer saddle element carries the weight of the first beam section to the second beam section at the opposite end thereof. The weight of a group of several vertically aligned beam sections is carried through bracket supports associated with large diameter return bends to the upright wall tubes at opposite sides of the gas pass. These load carrying brackets are below the level of the load they support and thereby in a lower temperature heating gas zone. By this construction it is also possible to divide the load of a pair of vertically extending multiple loop nested elements by arranging a plurality of pairs of vertically spaced bracket supports extending from large diameter return bends at opposite gas pass walls.

In each group of beam sections, wherein the weights are transmitted downward at positions adjacent the side walls of the gas pass by return bends and saddle supports, vertical alignment of adjacent beam sections is attained by relatively movable connections intermediate the lengths of the beam sections, the relatively movable connections permitting thermal expansion and contraction of adjoining beam sections.

A further feature of the construction is the pendent support of the lowermost beam section of each platen at the ends thereof from the superjacent beam section adjacent the bracket supports for the superjacent sections, thus providing additional heat absorbing surface adjacent these bracket supports.

With the individual tube platens constructed as described, the platens are maintained in a predetermined lateral spacing by studs mounted at spaced points on the sides of each platen and contacting the tubes of the adjacent platen.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

In the drawings:

Fig. 1 is a partly diagrammatic sectional elevation of a steam generating and superheating unit having a convection steam superheater constructed in accordance with the invention;

Fig. 2 is anenlarged elevation of a portion of the steam superheater shown in Fig. 1;

Fig. 3 is an enlarged fragmentary elevation of the end portion of the tube platen and support tube shown in Fig.2;

Fig. 4 is a vertical section taken on the line 4-.-4 of Fig. 3;

Fig. 5 is a vertical section taken on the line 55 of Fig. 3;

Fig. 6 is an enlarged fragmentary elevation of an intermediate portion of the tube platen shown in Fig. 2; Fig. 7 is a vertical section taken on the line 77 of Fig. 6;

Fig. 8 is an enlarged fragmentary elevation of another intermediate portion of the tube platen shown in Fig. 2; and

Fig. 9 is an end view of the parts shown in Fig. 8.

The steam generating and superheating unit illustrated in Fig. 1 has an upright furnace chamber 1 defined by steam generating wall tubes 2 and arranged for firing by fluid fuel burners 3. The high temperature products of combustion flowing upward through the furnace transmit heat to the furnace wall tubes and the steam generated therein is discharged to an elevated steam and water Patented Nov. 29, 1960' drum 4. The heating gases leave the furnace through a laterally extending gas pass 5 fi'om the upper portion of the furnace, and pass through a turning space 6 into a downflow gas pass 7 and a gas duct 8 leading to an air heater (not shown), from which the cooled gases are directed to theatmosphere.

Steam superheating and feed water heat absorbing surfaces of convection character are arranged in the gas pass 5 and downfiow pass 7. Saturated steam flows through tubular connections 10 to a. cross header 11 from which two sets of

tubes

12 and 13 associated respectively with the front wall 14, and with the roof and rear wall 15, of the downflow gas pass 7, discharge steam to a U-shaped header 16 which has portions along the twoside walls and the rear wall. Other tubes 17 convey steam from: the drum. 4 to opposite side wall headers 18, from which vertically extending tubes 19 lining the gas turning space 6 and downflow gas pass 7 convey steam to the U-shaped header 16.

The elevated supporting steel structure carries hangers 20 for the suspension of steam and water drum 4. Other hangers 21 for the header 11, hangers 22 for the rear wall tubes 13, and hangers 23 for the headers 18, suspend the vertically extending tubes of the four walls of the gas pass 7, as well as the weight of the steam superheater tubes carried on the front and

rear wall tubes

12 and 13 respectively, as hereinafter described.

A primary steam superheater 28 consisting of vertically spaced

banks

29 and 30 of transversely spaced multiple looped tubular platen elements spans the gas pass 7 between the front wall tubes 12 and the rear wall tubes 13. A feed water heater or economizer 31 consisting of a bank of transversely spaced multiple loop tubular elements is located below the primary superheater banks. While the economizer has corresponding long tube lengths which extend between the front and rear walls of the gas pass 7, it is supported from below by transversely extending beam members 32, which carry the economizer load into the side wall portions of the U-shaped header 16.

The steam flowing downwardly through the

wall tubes

12, 13 and 19 of gas pass 7 has been superheated to a minor extent when it enters header 16. The steam then leaves the header 16 through transverse rows of

tubes

33 and 34, which extend upwardly between the end of the economizer 31 and the rear gas pass wall 15. Each pair of

tubes

33, 34 are bent above the level of the economizer 31 in nested relation to form a vertical multi-looped tube platen forming part of the lower superheater bank 30, then upwardly in spaced sections 33A and 34A, and then laterally in nested relation to form a substantially similar platen forming part of the upper superheater bank 29. The uppermost horizontal lengths of the

tubes

33, 34 are extended upwardly in staggered

transverse rows

33B, 34B, of vertical tube lengths through the roof of the gas turning space 6 to a transverse header 36. A serial flow of steam thus occurs in each of the

tubes

33 and 34 from the header 16 through one of the platens of the lower bank 30, then through the corresponding vertical length 33A or 34A, and then through a corresponding platen in the upper bank 29, and a

vertical tube length

33B or 34B to the header 36.

Header 36 has a pipe connection 38, including a spray attemperator, to inlet header 39 of a pendent multiple loop secondary superheater 40 positioned in the laterally extending gas pass 5 between the furnace and the downflow gas pass 7. The secondary superheater has two serially connected sections 40A and 4013 joined by an external pipe 43 between the outlet header of the section 40A and inlet header 42 of section 40B. Steam is discharged through a pair of outlet headers 44 of the section 40B through pipes 45 to a point of use.

With the depth dimension between the walls 14 and of the gas pass 7 of the order of -22 feet and the

superheater tubes

33 and 34 made of carbon or low alloy steeland having an outside diameter of 2 /2" and a varying wall thickness consistent with pressure, temperature and allowable working stress requirements, the described nested arrangement of these tubes would not permit the support of these tubes at their looped ends without undue deflection of the horizontal tube lengths under the gas temperature conditions to which they are normally exposed in operation in a high capacity high temperature steam generating unit of the type illustrated in Fig. 1. The metal temperature of the

tubes

33 and 34 will be in the range of 8001000 F. in normal operation.

In accordance with the present invention, each of the

primary superheater banks

29 and 30 is formed by a series of side by side nested tube platens which are individually supported from the

tubes

12 and 13 at opposite sides of the gas pass 7. In the bank 29, for example, the adjacent vertically aligned horizontal tube lengths of the platens which are in parallelism as regards fluid flow, are rigidly connected together at longitudinally spaced positions, preferably by weld metal deposits 46 at opposite sides of a short filler bar 47. Seven such rigid connections are indicated in Fig. 2 between each pair of parallel flow tubes, uniformly spaced along the length thereof from points adjacent the looped ends thereof. Adjacent the front wall tubes 12 a pair of rigidly connected

horizontal tube lengths

33, 34 are joined to a similar. rigid pair of tube lengths in superposed alignment by large and small radius return bends 51 and 52 respectively, While adjacent the rear wall tubes 13, the last named pair of. tube lengths are joined to a subjacent pair of rigidly connected tube lengths by small and large radius return bends 53 and 54.

The weight of each long span rigid double tube beam section is carried at its ends. At the end where return bends connect to a lower subjacent pair, the weight is carried through the corresponding large radius return bend. At the opposite end a saddle member 55, which is rigidly mounted on a subjacent tubular beam section, partly embraces the tube of a superposed beam section and carries the weight thereof into the lower beam section.

By the described combination of return. bends and saddles, the weight of several elongated beam sections is carried on L-shaped

support brackets

56 and 57 mounted onthe

wall tubes

12 and 13 respectively. Depending L- shaped

arms

58 and 59 are welded to the adjacent large radius bends and arranged to rest on the short leg portions of the

support brackets

56 and 57 respectively. As shown in Fig. 3, each tube arm and correspondingsupport bracket has overlapping portions spaced sufficiently to permit expansion of the tube platen relative to' the support brackets.

As shown in Fig. 2, the upper primary superheater tube bank 29 has the individual tube platens formed by. nine superposed beam sections constructed as described. The substantial weight of each of these platens is supported by dividing the load between vertically spaced pairs of

support brackets

56, 57, the four uppermost beam sections being carried by a pair of brackets mounted on the

tubes

12, 13 at points intermediate the height of the bank, eachbracket carrying one-half the weight of the four beam sections. The next four beam sections are similarly supported from

brackets

56, 57, at opposite ends ofthe platen above the level of the lowermost tube beam sec tion where their exposure to radiant heat transfer from the gases in the cavity 7a between the superheater banks will be limited. In addition to carrying half the weight of four tubular beam sections which are above the bracket level, the lower support brackets also carry the weight of the lowermost tubular beam section by pivoted

hangers

71 and 72 engaging lugs 73 on the lowermost large radius bends, to carry the weight into the large radius return bends to which the hangers are directly attached.

Intertube ties between the lower tube of one tubular beam section and the upper tube ofa subjacent beam section, preferably midway of the length thereof, are pro vided to maintain vertical alignment of the beam sections of the platen. As shown in Figs. 2, 6 and 7 these ties consist of pairs of spaced horizontally aligned

sleeves

63 and 64 welded to the lower side sector of a tube length and a single pair of sleeves 65, between, spaced from, and aligned with the pairs of

sleeves

63 and 64, welded to the upper side sector of the subjacent upper tube length of the next lower beam section. Pins 66 extending through each set of three aligned sleeves keep the tubular beam sections in platen alignment while permitting relative longitudinal movement between the adjacent beam sections.

As shown in Figs. 3, 4, 6 and 7, T-headed stud members 74 are attached to one side of the top and bottom tube lengths of each bracket supported group of beam sections to provide lateral spacing relative to corresponding tubes of the adjacent platen, the T-head of the stud being arranged to abut the laterally adjacnt tube. These stud members are distributed over the one side of each platen, both longitudinally and vertically, and insure uniform spacing of the gas flow passages between the platens.

Rows of refractory tile 75 are arranged to close the small gaps between the front and

rear wall tubes

12 and 13 and the adjacent ends of the uppermost return bends of each bank, to prevent hot gases with corrosive constituents flowing directly downward through the space between the wall tubes and the return bends, thus minimizing heating to the support brackets and the collection of corrosive material thereon. These tile are held in operative relationship by clip members 76 welded to the uppermost tube length at that point.

The described construction provides a highly effective arrangement for spanning gas passes of substantial depth with heat transfer tubes subject to high temperature heating gases, while minimizing the possibility of overheating and corroding the tube supporting parts.

While in accordance with the provisions of the statutes I have illustrated and described herein the best forms of the invention now known to me, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by the claims, and that certain features of the invention may sometimes be used to advantage without a corresponding use of other features.

This application is a continuation-in-part of my prior copending application, Serial No. 596,908, filed July 10, 1956, now abandoned.

What is claimed is:

1. In a fluid heater having a vertically extending heating gas pass of substantial width, a horizontally arranged bank of fluid heating tubes extending across the full width of said gas pass and comprising a series of side-by-side tube platens arranged in parallel vertical planes, means for supporting said tube platens for horizontal thermal movement from opposite sides of said gas pass, each of said tube platens comprising a plurality of multi-looped nested fluid heating tubes, each fluid heating tube being arranged in successive vertically spaced horizontal tube legs having a vapor flow in opposite directions therein and alternately connected at their ends by small and large radius looped portions, each pair of tube legs connected by a large radius looped portion having a pair of vertically spaced horizontal tube legs of the other tube serially connected by a small radius looped portion positioned therebetween and in vertical alignment therewith, whereby two pairs of superjacent tube legs are formed by the corresponding tube legs of said nested fluid heating tubes, means for maintaining a fluid flow in the same direction through corresponding superjacent tube legs of said plurality of fluid heating tubes, means for rigidly connecting at points along the length thereof only superjacent tube legs having a fluid flow in the same direction therethrough, to form a long span tubular beam structure extending across said heating gas pass, and relatively movable means forming an expansible supporting connection between and at an intermediate point along the length of each pair of superjacent tube legs having fluid flows therein in opposite directions. I

2. In a fluid heater having a vertically extending heating gas pass of substantial width, a horizontally arranged bank of fluid heating tubes extending across the full width of said gas pass and comprising a series of side-by-side tube platens arranged in parallel vertical planes, means for supporting said tube platens for horizontal thermal movment from opposite sides of said gas pass, each of said tube platens comprising a pair of multi-looped nested fluid heating tubes, each fluid heating tube being-arranged in successive vertically spaced horizontal tube legs having a fluid flow in opposite directions therein and alternately connected at their ends by small and large radius looped portions, each pair of tube legs connected by a large radius looped portion having a pair of vertically spaced horizontal tube legs of the other tube serially connected by a small radius looped portion positioned therebetween and in vertical alignment therewith, whereby two pairs of superjacent tube legs are formed by the corresponding tube legs of said nested fluid heating tubes, means for maintaining a fluid flow in the same direction through corresponding superjacent tube legs of said pair of fluid heating tubes, means for rigidly connecting at points along the length thereof only vertically spaced pairs of superjacent tube legs having 'a fluid flow in the same direction therethrough, to form vertically spaced long span tubular beam structures extending across said heating gas pass, and relatively movable means forming an expansible supporting connection between and at an intermediate point along the length of tube legs of superjacent vertically aligned beam structures having fluid flows therein in opposite directions;

3. In a fluid heater having a vertically extending heating gas pass of substantial width and vertically extending fluid heating tubes lining a pair of opposite side walls of said gas pass, a horizontally arranged bank of fluid heating tubes extending across the full width of said gas pass and comprising a series of side-by-side tube platens arranged in parallel vertical planes, each of said tube platens comprising a pair of multi-looped nested fluid heating tubes, each fluid heating tube being arranged in successive vertically spaced horizontal tube legs having a fluid flow in opposite directions therein and alternately connected at their ends by small and large radius looped portions, each pair of tube legs connected by a large radius looped portion having a pair of vertically spaced horizontal tube legs of the other tube serially connected by a small radius looped portion positioned therebetween and in vertical alignment therewith, whereby two pairs of superjacent tube legs are formed by the corresponding tube legs of said nested fluid heating tubes, means for supporting large radius looped portions of said tubes on the fluid heating tubes along opposite side walls of said gas pass, means for maintaining a fluid flow in the same direction through corresponding superjacent tube legs of said pair of fluid heating tubes, means for rigidly connecting at points along the length thereof only vertically spaced pairs of superjacent tube legs having a fluid flow in the same direction therethrough, to form vertically spaced long span tubular beam structures extending across said heating gas pass, and relatively movable means forming an expansible supporting connection between and at an intermediate point along the length of tube legs of superjacent vertically aligned beam structures having fluid flows therein in opposite directions.

4. In a fluid heater having a vertically extending heating gas pass of substantial width and vertically extending fluid heating tubes lining a pair of opposite side walls of said gas pass, a horizontally arranged bank of fluid heating tubes extending across the full width of said gas pass and comprising a series of side-by-side tube platens arranged in parallel vertical planes, each of said tube platens comprising a pair of multi-looped nested fluid heating 7 tubes, each fluid heating tube being arranged in succes sive vertically spaced horizontal tube legs having a fluid flow in opposite directions therein and alternately connected atitheir ends by small and large radius: looped portions, each pair of tube legs connected by a large radius looped portion having a pair of vertically spaced horizontal tube'legs of the other tube serially connected by a small radius looped portion positioned therebetween and in vertical alignment therewith, whereby-two pairs of superjacent tube legs are formed by the corresponding tube legs of said nested fluid heating tubes, means for supporting large radius looped portions of said tubes on the fluid heating tuges along opposite side walls of said gas pass, means for maintaining, a fluid flow in the same direction through corresponding superjacent tube legs of said pair of .fluid heating tubes, means for rigidly connecting at points along the length thereof only vertically spaced pairs ofsuperj'acent tube legs having a fluid flow in the same direction therethrough, to form vertically spaced long span tubular beam structures extending across said heating gas pass, and means forming an expansible supporting connection between and at an intermediate point along the length oftube legs of superjacent vertically aligned beam structures having fluid flows therein in opposite directions comprising longitudinally spaced and aligned sleeves mounted on said last mentioned tube legs, and a rod extending through said sleeves.

5. In a fluid heater having a vertically extending heat ing gas pass of substantial width and vertically extending fluid heating tubes lining a pair of opposite side walls of said gas pass, a horizontally arranged bank of fluid heating tubes extending across the full width of said gas pass and comprising a series of side-by-side tube platens arranged inparallel vertical planes, each of said tube platens comprising a pair of multi-looped nested fluid heating tubes, each fluid heating tube being arranged in successive vertically spaced horizontal tube legs having a fluid flow in opposite directions therein and alternately connected at their ends by small and large radius looped portions, each pair of tube legs connected by a large radius looped portion having a pair of vertically spaced horizontal tube legs of the other tube serially connectedby asmall radius looped portion positioned therebetween and in vertical alignment therewith, whereby two'pairs of superjacent tube legs are formed by the corresponding tube legs of said nested fluid heating tubes, means for maintaining a fluid flow in the same direction through corresponding subjacent tube legs of saidpair of fluid heatingtubes; means for rigidly connecting at points along the length thereof only successive pairs of superjacent tube legs having afluid-flow in the same direction therethrough, to form a plurality-of vertically spaced long span tubular beam structures extending across said heating gas pass, relatively movable means forming an expansible supporting connection between and'at an inter mediate point along the length of superjacent tube legs of superjacentvertically aligned beam structures having fluid heating tubes, meansfor rigidly connecting at points bottom supporting a plurality of said vertically spaced tubular beam structureson the fluid heating tubes along said opposite side walls of said gas pass.

6. In afluid heater as claimed in claim 5, in which the means for bottom supporting a plurality of said tubular beam structures on the fluid heating tubes along said opposite side walls of said gas pass comprises support means above the level of the lowermost tubular beam structure in said platen, and means for pendently supportingsaid lowermost tubular beam structure from the superjacent bottom supported tubular beam structure.

ReferencesCited in the file of this patent UNITED STATES PATENTS 1,894,692 Kerr et al. Jan. 17, 1933 2,067,671 Kooistra Jan. 12, 1937 2,243,430 Lucke May 27,1941 2,310,801 Mayo etal. Feb. 9, 1943 2,714,877 Andrew Aug. 9, 1955 2,800,113 Kessler et al. July 23, 1957 2,809,616 Black Oct, 15, 1957 UNITED STATES PATENT OFFICE QERTIFICATE 0F CORRECTION Patent No 2, 962 OO7 November 29 1960 Paul H, Koch It is hereby certified that error appears in the above numbered patent reqiiring correction and that the said Letters Patent should read as corrected below.

Column l line 31 for articular" read particularly column 8, line 18, for "fluid heating tubes means for rigidly connecting at points" read fluid flows therein inopposite directions and means for -o Signed and sealed this 3rd day of December 1963.

SEA

Heat. EDWIN LI REYNOLDS ERNEST wo SWIDER Attesting Qfficer Acting Commissioner of Patems