US2607567A - Heat exchanger - Google Patents

Description

J. c. HOBBS 2,607,567

HEAT EXCHANGER 3 Sheets-Sheet 1 z w B 2 m AN/ W7, A 4 m s M1. fi M C m 6 v n w i? 52%.? J J W M Q Aug. 19, 1952 Origin a1 Filed July 51, 1940 ATTORNEY.

A g- 1952 J. c. HOBBS 2,607,567

HEAT EXCHANGER' Original Filed July 31, 1940 3 Sheets-Sheet 2 INVENTOR.

25 James C 0515.9

ATTORNEY.

A g- 1952 J. c. HOBBS HEAT EXCHANGER 3 Sheets-Sheet 3 Original Filed July 31, 1940 INVENTOR gamm (Ii /ebb ATTCRNEY Patented Aug. 19, 1952 HEAT EXCHANGER James C. Hobbs, Painesville, Ohio Original application July 81, 1940, Serial No.

348,839, now Patent No. 2,363,526, dated November 28, 1944. Divided and this application November 24, 1944, Serial No. 564,951

3 Claims. 1

The invention herein disclosed relates to heat exchangers of a type wherein heat is transferred from one fluid medium to another within an enclosing pressure vessel. Whereas, in some forms of heat exchangers one fluid may be brought into direct contact with another, in others of the type specifically described herein, one fluid may be confined within tubes disposed within the vessel and another admitted to the vessel into intimate contact with such tubes, whereby the tube walls constitute intermediary heat transfer surface between the fluids.

The invention has for an object the provision of a heat exchanger wherein the transfer of heat from one fluid to another is accomplished with high efficiency and maximum utilization of the fluid having the higher temperature.

Another object is in the effective utilization of intermediary heat transfer surface as in the case for example where one of the fluids is carried within tubes, and the other within an enclosing shell.

A further object is the provision of a structure having long lengths of small diameter heat exchange tubes arranged in a bundle and suitably supported against vibration and displacement by means arranged to improve heat transfer.

An additional object is the provision of a fluid heat exchanger having heat transfer surface formed by a bundle of tubes disposed within an enclosing shell suitably constructed in sections to facilitate access to the tube bundle.

Other objects pertain to improvements in the formation of fluid-tight joints between associated parts of the structure described, and in the utilization of fluid pressure in maintaining such joints in a fluid-tight condition irrespective of relative movement of the parts.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For 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 I have illustrated and described a preferred embodiment of my invention.

Fig. 1 of the drawings is an elevational view in section illustrating an embodiment of the invention;

Fig. 2 is an enlarged fragment of Fig. 1;

Fig. 3 is a plan of the Fig. l embodiment;

Fig. 4 is a plan section along line 4--4 of Fig. l;'

Fig. 5 illustrates a detail;

bundle of tubes l I.

Fig. 6 illustrates the element of Fig. 5 as assembled;

Fig. 7 is a fragmentary enlargement of Fig. 6, partly in section, showing a tube-supporting plate in two different positions; and

Fig. 8 is a partial plan view of Fig. 7.

The embodiment to be described is the same as disclosed in my copending application Serial No. 348,839, filed July 31, 1940, now U. S. Patent No. 2,363,526, issued November 28, 1944, of which the present application is a division.

The heat exchanger illustrated in Fig. 1 includes an elongated pressure vessel I, wherein a generally cylindrical shell 2 is provided at opposite ends with pressure heads 3 and 4 welded thereto. The shell 2 is preferably formed of a plurality of telescoping sections 5, 6, 1, 8 of different diameters with adjacent sections removably connected by pressure-sealed joints 9, I0 which permit relative movement, as more fully described hereinafter. Tubes I l which extend interiorly of the shell and are preferably arranged in closely spaced relation in a bundle throughout its length are seated at their ends in the heads 3, 4 to provide a path for one of the heat exchange fluids. Fluidtight connections I2 and I3 are made to heads 3, 4 to provide the desired inlet and outlet connections for the fluid which is conducted through the This form of heat exchanger is particularly adapted for use in an upright position, that is, with the longitudinal axis of the shell extending vertically, in which case a liquid such as boiler feed water under pressure may be caused to flow upwardly through the tubes II, the lower connection [2 constituting a water inlet connection and the upper connection It a water outlet connection. A condensible heating medium such as superheated steam may be admitted to the shell through one or more connections I4, I5 adjacent the upper end of the tube bundle, and directed into intimate contact with the tubes through which the cooler fluid is conducted.

An arcuate baffle I6 is spaced inwardly of the shell 2 opposite each of the vapor connections l4, [5 to prevent impingement of the entering stream of high temperature vapor against the tubes II, the bafiie preferably being removably supported within the shell by having its upper edge received in a recess I! in head 4, and its lower edge welded to an arcuate bar [8 removably secured to the shell. as by a plurality of connectors, such as cap screw 19. The stream of vapor is thus diverted circumferentially around the lateral edges of the baffle IE and enters the tube compartment at decreased velocity through the openings 20 adjacent the interior wall surface of the uppermost shell section 5. It will be noted that in this arrangement, section 5 of the shell being of maximum internal diameter, as compared with an adja-, cent section 6, provides a greater space surrounding the tubes into which the entering vapor may expand and become more uniformly distributed at the beginning of its downward course over the tubes.

The tubes H are supported at intervals along their lengths by means of plates '21 which also serve as battles for directing the now of heatingfluid over and along the'tul'oes in a substan-: tially sinuous path generally counter tothe up} ward flow of the liquid within the tubes. Each their former positions to: effect a sufficient resupporting plate or bafiie 21 as detailed in Figs. I

and 6 extends inwardly across the tube bundle from an outer position including the outermost row of two tubes 22 to an" inner position including the central row of fourteen tubes 23, each plate being of segmental. formation and having clearance holes 24 "oflt fi. am arran and center-to-center spacingasitubes I], and each plate terminatingin an inner chordal edge 82 m th.- emicircu arjre je s s. affording engag 'ement'with tubes an additional. parallel nww.

Th plat ispivo a ly, upportedat .5. 3. pr jections of weld; metalffor' exampie onftubes of the centralrowj 2312,1151, dueto the clearances providedaround the tubes l I each plate may be initiallyarranged in 'ani assembling position substantially noijma ljtofthe' tn 'esjand finally assembledjiin an inclinedposit onacross the tube bundle With, the lower {outer edgej adj acent the innerfwall of the shjellt'ln the inclined as sembl'ed' o it on he p ates ar we ed between successive rows' 'of tubes' so at with the plates arranged,in.overlappingstaggered. relation, as wn li ubes; i". erinc edor t d ethe throughout thelbundlejto."maintain; the tubes in spaced relation. andfto .entfv'ibration. Ilie relationship; of a plate '21 to'tubes I], in each' of b GJmBnti nedpo itions u tra e in Fig; 7 ;'.'the broken-line representations, showil ig the plate. injthej initial". assembling position, at

right "'anglesito, 'the tubes', "whereby. tube. holes I 24 provide .annul'arj'clearance spaces about the respective tubes; and the. solid line representa:

tions i'showing the plate 7 in the inclined; op erating position'in' which tubes] I are deflected from their original 1 broken line positions and thus. are engaged by theplate at diametrically opposed locations. The usei'fof circular tubeholes 2am combination with tubes I l of smaller circular cross section results in .each encircled tube being gripped at oppositeendsof, its diameter in the direction normal to the tube rows, while at oppositesides of eachjtllbe, in alignment with/the rows, the tube holes remain spaced from the tube walls substantially throughout their peripheries to provide. heating fluid passages 7 24 (Fig. 8) which contribute; to 'intimateQheat transfer contact with the tubes close to the baflles 2L In a heat exchanger of theproportions indicated, in commpnlwith'pi iopart structures of this general type, the intermediate portions of tubes I], between heads 3 a are of lengths many. times their diameters and thus have an inherent flexibility which renders them free to vibrate in service'unless suitable restraint is imposed. This inherent flexibility of the tubes is i HI...

on. the. olts as f rnolding the. m ro-per. assembled. relatio -an gf fadii st b i as irin he vaki duction in row-to-row tube spacing in the vicinity of the plate to cause the plate toengage tubes in successive rows at opposite ends of ach tube diameter.

The 't'ransferjof heat from the hotter vaporous medium to the colder fluid results in a condensation of vapor within the shell and the formation of a pool of condensate at the bottom. A valved connection 2 provides a means for withr w n ondensat rom. he s e l. s. r uire o x m Q ilea in or 9 1" Hittin he pth w iq he wh ri aie ntimated o cc mu te hsf veli ndensa e. may. e u oma ly m in ained; at? a. ubstantial y n an r stermi cd- 'a ue, by. mans. i; a. ow e of fleatf i e i a inaumien and lower. on i nslfii fly l 'ne tive yi o he. or d o ensa e was o he. sse andg el n operativelyv connected'jas by rod to; to the .vajlve 3! in the drain connection 26;

The pressure heads 3 and 4 are provided with access p nin s. 3 hi h are fiiiekl it i r mo ableco-vers or closure mbers 33 eachin the m a sq id ist e .resi wiih l ihe. li slrr. cal inner end portignjfi;ofjhe opening tgi The circumferential surface of; the .inen ber. 33; ind s. an. n er. nqri 55'; f. a. am ter. are: i'naa r s ric d. .l afii s? e aiir t heseface 34 and an outer portigintiof reduceddiameter providing an annular recess 31-for one or more layers of packing. 38.. T'hebase St ci the recessis in clined tqjthe central axis of the.

e ing n o ncid slwit he surfac f Merle having i s. pexr ard.theexterior f t e fittina A follower ring dli ha's 'an und er bearing surfacel an .initial. comprs'siyej force on t sufficient to; seal; the jo t ,at lo sures, During, normal op offluid Within th' vesselje ts an compressive'force which will cause. he ing to. expand radially and along the faces of the recess and fOlIOW-flillllgktqj increase the tightness of the joint. Nutsfifi be welded or otherwise securedto thebolts dd at their outenends for convenience in turning the bolts intoand out of the covr'tt A joint is provided for :eacl rBfft'he water-connections i 2, l3 which-is similar -in certaini'- l se.

spects to that provided for the-cover 33. The head 4 for example is counterbored to provide a transverse seating surface 50, a conical seating surface 5|, and a cylindrical joint surface 52 of a diameter providing an annular space 53 around the pipe [3. A base ring 54 of rhomboidal cross section as shown, may be welded to the pipe as by weld metal 55, the ring providing an upper bearing surface 56 of conical formation relative to an apex toward the exterior of the head 4. The advantage in thus providing the desired enlargement at one end of the pipe or tubing I3 is that forging of the pipe end is avoided, and the resulting welded connection is subjected to relatively low fiber stress because of the wide circumferential band over which it extends and because of the fact that longitudinal stresses in cylindrical hydraulic structures are only one-half the radial stresses. The inner end of the compositely formed pipe I3, including the base ring 54 and weld metal 55, is shaped to provide surfaces companionate to the counterbore surfaces 50, 5|, 52 in order to restrict the leakage path for fluid when'the pipe 13, including its integrally associated parts, is in the normally seated position within the counterbore. A ring of packing 5! is inserted within the annular space 53 and is contacted by the under bearing surface 58 of follower ring 59 of the same angularity as the opposing bearing surface 56 of base ring 54. A pipe joint bushing or nut 60 is threaded into the outer end of the counterbore, utilizing threads 6| of relatively large pitch and clearances, the bushing bearing against the outer surface 62 of follower ring 59 over a common area of contact in a plane normal to the axis of the joint.

The expansion joints 9, ID for connecting adjacent sections of the shell 2 are of a type permitting relative movement of the telescoping parts without subjecting the joints to longitudinal forces, and facilitating access to the tube bank for external inspection throughout a sub stantial portion of its length. Referring to Fig. 2 in which a joint 9 is detailed, between shell sec-- tions 5 and 6, for example, the inner shell section 6 is provided with a circumferential band 63 having an outer facing 64 of corrosion-re sistant metal, the band being secured to the section 6 as by weld metal 65, and a stop ring 66 being secured to the band 63 adjacent its inner margin as by weld metal 61. When the facing 64 is formed of a separate metallic sheet instead of an integral surface structure of the band 63, one edge of the facing sheet may be flanged over an edge of the band 63 as at 68 and held in place by the fillet weld 65, the other end being extended beyond the stop ring 66 and held in place by the fillet weld 61. The outer shell section 5 is provided with a stop ring 69 spaced from its end and secured in position as by weld metal the stop ring 69 being of larger inside diameter than the outside diameter of stop ring 66 and having a bearing surface 1| normal to the central axis of the section as a seat for the correspondingly surfaced removable filler ring 12 which forms the base of the annular packing space 13. The inner transverse surface 14 of the filler ring 12 is of conical formation relative to an apex toward the inner end of the inner section 6, the ring of compressible packing material being clamped between the conical surface 14 and an opposing surface 76 of the same angularity on the follower gland 11. A flange I8 is provided on gland 11 for the accommodation of holding bolts 19 which are screwed into lugs 80 on the outershell section 5, a nut 81 being fitted to each bolt-19 for adjustably compressing the. packing 15. I I L Joints 9 and H) are identical in construction although reversely arranged, as seen in Fig. 1; joint 9 arranged as in Fig. 2 being utilized between the upper end of an inside-fitting section 6 or 8 and the lower end of an outside-fitting section 5 or vI; and joint Ill, reversely arranged, being utilized between the lower end of an insidefitting section 6 and the upper'end of an outsidefitting section 1. 7

When the joints 9 and IOIare completely assembled, thefiuid pressure exerted thereon from within thesshell serves to maintain the joints in fluid-tight condition. The stop rings 66 and 69 being radially spaced as shown permit the desired relative movement between adjoiningsections, whilestop rings 66 limit the extent of expansive movement .at the respective joints, as determined by the longitudinal spacing of each stop ring 66 from the adjacent filler ring 12, thereby preventing the separation of adjoining sections, while maintaining the desired minimum .overlap between adjoining sections and assuring the proper relative positioning of the cylindrical sealing surfaces.

It will be understood from the construction illustrated that, in order to obtain access to the tube bundle, any one. of the intermediate shell sections may be raised or lowered relativeto an adjoining section to provide the required length of access opening. For example, for access to various parts of the tube bundle, after loosening or disassembling the respective joints 9 and I0; section 1 may be raised to clear section 8 for access to a lower part of the bundle; section 6 may be lowered to clear section 5 for access to an upper part of the bundle; or section I may be lowered and section 6 raised to provide a space for access to an intermediate part of the bundle. The sections may be moved without interference from the internal stiffener plates 2| which are formed and assembled to fit within the section of minimum inside diameter and being supported solely on the tube bundle are free of any connections with the shell section; nor do the high pressure fluid connections to the heat exchanger need to be disturbed except small connections such as 28 and 29 which may be broken at 84, for example, when it is desired to move section 1.

Heat exchangers of the type described have a fundamental characteristic in that the metallic components are relatively thin throughout, notwithstanding the very high operating pressures of one or both of the heat exchange fluids; at the same time the unit stresses are relatively low as compared with the high stresses involved in prior apparatus operating at the same or even lower pressures. The fact that the sizes of the pressure chambers are reduced to a minimum results in a decrease in pressure loading, thus contributing to lower material costs and weights, the latter being an important factor in providing adequate support of the device in the plant.

I claim:

1. In a heat exchanger comprising a vertically elongated shell, a bundle of vertically extending tubes enclosed by said shell, means for supporting said tubes at their ends, an intermediate support for said tubes comprising a plate assembled transversely of said bundle in an inclined position, said plate being of segmental formation and having openings therein of the same arrangement and spacing as the tubes of said bundie, saidv openings providing clearances annularly of said tubes in a right-angled assembling position and providing engagement with individual tube circumferences at opposite locations in the inclined assembled position, and means for pivotally supporting said plate from tubes of said bundle adjacent an upper margin.

2. a heat exchanger. comprising a vertically elongated shell, a bundle of vertically extending tubes enclosed by said shell, means for supplying fluids of different temperatures to said shell and tubes for flow therethrough' in heat transfer relation, and baffles for'directing the flow of fluid throughsaid shell while laterally supporting said tubes against vibration, said baflies comprising plates: ofsegmental form extending partiallyacross said bundle in an inclined position with their curved marginal edges spaced from the inner wall of said shell, said plates being formed with openings providing engagement with individual tube circumferences at diametrically: opposed locations while clearances remain at intermediate circumferential locations, and means for pivotally supporting said plates from intermediate tubes of said bundle.

3, In a heat exchanger comprising a vertically elongated shell, a bundle of vertically extending tubes enclosed by said, shell, means for supplying a fluid to be heated to said tubes, inlet. means foradmitting a condensible heating fluid to an upper portionrof said shell, outlet means for withdrawing condensed fluid from a lower portion, bafiles extending partially across said: tube bundle at spaced positions intermediate said inlet and outlet means, said bafiles being inclined downwardly toward said shell and being formed of plates having clearance openings providing engagement with individual tube circumferences at diametrically; opposed locations while clearances remain at intermediate circumferential locations, and means for pivotally supporting each plate adjacent an upper margin.

JAMES C. HOBBS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITEDSTATES PATENTS Number Name Date 596,874 Hand Jan. 4, 1898 745,312 Baragwanath Dec. 1, 1903 1,335,506 Jones Mar. 30, 1920 1,633,975 Broido June 28, 1927 1,770,208 Kemnal July 8, 1930 1,882,474 Black Oct. 11, 1932 1,994,779 McNeal Mar. 19, 1935 2,102,723 Kotzebue Dec. 21, 1937 2,232,936 Bimpson Feb. 25, 1941 2,363,526 Hobbs Nov. 28, 194i FOREIGN PATENTS Number Country Date 4,071 Great Britain Nov. 2, 1877 514,024 France Feb. 4, 1920

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