US2550560A - Heat exchanger - Google Patents

Description

55512 1951 v DHE N 2,550,550

HEAT EXCHANGER Filed Jan. 21, 1946 v I 23 v 9 F/G. 5 F/5.. 6

I Wye/ Mar #11; Hero)? Patented Apr. 24, 1951 HEn'n-ExcnANG-En Hu h:Dl.lzleron,.Q filiemont,Quebec Cantabile Application Januarv zl, 1946' S'erial Nm @425 This inventioni.relates;to.imgirovementsdnzths;

beunderstoodthe inventionis snottherebyilimitedi.

to that application but; extendsito otherr typesoofir heatiexchangersw Theiprimary object of; the invention isitogprna vide, imcombinationxwithia; construction-imam eral according to my saidiear-l'ien; invention; ands; with the retention-of allithe advantagesrthereofi; means for holding." the; exchangere tubes: against... creeping through: the. packing thereof and; through. th tube; plates and; against; oscillatory;

movementwhichv tends tofiloosen theipacking cause leakingp Ar. further. objecta.is.:. to; provide: construction permitting :free. movement. of; tubes. in expansion and; contractioni due toatempera-a tul e changes; without damage. to. packing; and: with: exclusion of grit; muwon'scaleifromithez.

' clearancebetween the'tubeszandttheitube holding.

means. A stilhfurther object:isitozprovideaprotece tion againstrdrying out tofu the packingi Wham. an

exchanger istemporarily: outofiservice... Another.

obiect is to provide a construction:which.zisieasei ier and less: expensivetoiproduceiand} whicinmay; more easily and quickly assembleds. thanthe: cone. struction-nowin generala use; Still: another obao ject is to; provideconstruction;apphcableztm exist-t. ing exchangers having the: usualz internallyr threaded packing chambers; either'to convertrthe. same to embody the-1 featuresc ofsthisi and; of former invention on asi anaemergency:- substia, tute for the: usual connectionobetweern tub esiand tubeplates. Various othen objects: anduthe; aria, vantages of' theinvention may; be v ascentained; from the following descriptioniand ztheiacconn;

panying draiwingsi v 'Ihe inventiom CQnsiStS-l esSentia-Hyu 1m providing}. a heat exchanger having. packing. receiving-z lies cesses in the tube p1ates-,.thereof: formed; to; n 1;. ta-im packing therein independentlit of: anyo addict. tionak retaining; means combina on: with.

means. adapted: to. hold the. enchaneera tlihQ ii against creeping through the: tube pla es and: packing; toiexchide; foreign matter: from between; mambeseandetheiholdi a-meansi h r for to; protect. thenaokingyaea ns the effect o woe. bra o .andt against dra utwhe. the changer stem-po ar ye atof In gr at de aii,p.. he n-yen insist features; an c m. a ns. fizi fl ll' fi he closed eaether w t a l su h. modifl a icmr esitant-a d: ubstitutions; a v sher araw th'ni lae we iqathe eleven .efli leemen In. the accompanying. dIaWii1gSh formina. part:

or this specification; which illustrate. hfiikf lfmz.

of the invention nowzpreferredi'for new onstruqev. tion; andr further: iilustnatei modifications theme. ofzfor the adaption ofirtheiinventiomto .existin condensers; but-to.atheidetailsiofrail IOf': whichithea invention is:.-not;confine.d3i r Fig; .1; fragmentaryiside: elevatiomofsaiconn denser.

Fig; Zwis: an:- elevation;- of iar-frag'mentcogf a tubse plate. ShOWi'Ilg. the: ends? of? tubes: and; netainingr means therefor:

Fig.*.-. 3 is; a; section: om the line: 3&3: of. Fig. showing: the. relatiom of; the: pants: asinnwz prev; ferredzfor new. construction.

Fig. .v 4. is! a; section; simil'an to.. that:. of 3;.

showingmodifications;

Figs; 5*,ami '6tarei sectionsisimilanto thatioiszfi a 3, showing ways ofradaptingithe inventionetoiene; istingcondensers;

Reiernin imoreparticularly-to.theidrawingsr t1; designatest condensen tube; 131817.381 and I22 01k; densertubes mountain in the..- nlatesi... tuba. platesiare formed: with wen wrestle; therein ionpassage. oife the. tubes,.. which. anentures: are. 115113.

1 ally.locaztect as close, together ass.is.; pQSSib1e; cone sistent witmadequate strenethrcf thatube plate.

so as to provide the maximum number of tubese withini a. given; 513343332. Eacln apenture: I132; comprises; three, ortions: namely; aniinner portion I43; .amintermediate; portior-inlfiaand.anaoutelt D9. time 61. Theinnenmortion I-Jhis c-linsirioal; andr oti'such odiametergthat thatub iszani eas -s1id' in nttnerein- Theiintermediate;.portiqnrtiaiao larger-diameter; than theiinnere portion smasutila;

7 provide an annular packing space around the-3;

tuba; thetshoulderr H between the jinner: andr the intermediate portions-L being; preferablyfla-ti, and: normal to. the; aperture axis; but; may; be; other wise formed: The. circumierentialiwalla 0:: meme. tern-mediates. portion; is: tapered through at: leasia a; part of its: depth; towardztheouten end, of the;

aperture so as to.; form a-.-.shon1der, fafiin a the; hou de I; but mast-be cylindrical n; ts-Amen portion, as. showniati with R -.42. he; f ren ial; wall; o he outer ner ure o Ht: s preferably y i dr al and eferablyw ehtlryi greaterdiameter-than t e outer 3 505 the lia fifim d p on L5 e, as e; rz nvisle. a, nar ow:- shoulder. l9,- at: the junction: 0 2 he intermediate nd: outerportions. Preferably-the; diametepot: heu e po Hi. is. anprot me r meme; as-the maximum diameter of the. intermediate portion; as. shownsin Fig, abut-may, bed v same. diameter as the out r nd: f. he int mediate p rtion... asshown in E a, which. case, there. no, shoulder. t9... The} depth oi. the; outer. portion is materially greater'than m lon. gitudinaliexpansion of the tube l2, prefe iablgl three-to. five. times he xp nsi n.

The. maximum diameters. of. the. nertutqa it In the outer portion l6 of each aperture there is provided a metal washer or ring 20 which preferably completely fills the aperture around the tube and which is an easy sliding fit' on' the aperture wall and on the tube, so that the tube may move freely through the ring when expanding or contracting. Normally the ring rests on the seat I9 and the outer end surface of the ring is flush with the outer surface of the tube plate I I. The bore of the ring is flared from the inner end surface of the ring, or from a line adjacent the inner end surface of the ring, as shown at 2|, to within a short distance of the outer end surface and is parallel, or cylindrical, from the flare to the outer endsurface of the ring, as shown at 22. The depth of the parallel portion 22 is at least as great as the longitudinal expansion of the tube when heated in service. The total angle of flare is preferably from 10 to 30.

The packing now preferred is a single sleeve 23 of water swellable compressed fibre which, in

its dry condition, is an easy sliding fit on the tube and intothe small end of the intermediate aperture portion [5. The length of the packing sleeve is preferably only slightly less than the depth of the intermediate aperture portion.

The sleeve 23 is preferably composed ofthat type of material formed by winding a ribbon of paper or the like impregnated with a suitable binding agent, around a mandrel until a suitable wall thickness is built up and then compressing the tube in its radial direction. Sleeves of such material, when exposed to water, swell radially but 'do not swell appreciably in their axial direction.

If desired, instead of using a single sleeve, I may use a series of rings or washers 2i of the same material, as shown in Fig. 4. This subdivision of the packing into rings facilitates penetration of moisture to all parts of the packing and"thereby expedites swelling of thepacking but has the disadvantage of longer assembly time.

The length of the tubes l2, when cold, is preferably less than the distance between remote faces ofthe tube plates H by about twice the longitudinal expansion of the tubes when heated to maximum working temperature, so that, when cold, the ends of the tubes are slightly below the outer surfaces of the tube plates, as shown. Thus, even if one end of a tube remains fixed, the longitudinal expansion resultant of heating to maximum working temperature will not cause the free end of thetube to project beyond the surface of the tube plate. In this way turbulence of fluid in the condenser is avoided.

f After the tubes are in place in the tube plates and the packing and end rings have been inserted at both ends of the condenser in the manner shown, both ends of each tube are flared or radially expanded into surface contact with the flared bore portions 2| of the end rings 20. The radial expansion of the tube ends is only that sufiicient to hold the tubes-against creeping due to expansion and contraction, to inertia and to the urge of unidirectional flow through the tubes and does not normally place the tubes under tension between the tube plates at opposite ends 4 of the condenser. It is not the intention that flaring of the tube ends should so expand the same in the rings 20 as to interfere with free sliding of the tubes through the rings. It will be readily understood that, because of the outward flare of the ring bores, the tubes can be expanded, when cold, into substantially fluid tight contact with the flared surfaces of the rings without interfering with the free movement of the tubes through the rings as the tubes expand with heating.

When the tubes are radially expanded, the outer end edges thereof are in contact with the inner ends of the cylindrical bore portions 22 of the rings 20. As the tubesexpand longitudinally with heating, the outer and edges thereof maintain contact with the cylindrical bores 22 of the rings and exclude mud, scale or'the like from entering between the now spaced flared portions of the tubes and the flared bore surfaces 2! of the rings. Thus, no foreign matter can enter between the flared surfaces and set up tension in the tubes when they 'cool and contract.

When the condenser is assembled, there is a small annular clearance '24 around the inner end of each packing sleeve, which clearance tapers to nothing at the outer end of the sleeve, as clearly shown in Figs. 3 and 4. In service, moisture penetrates into the intermediate aperture portion l5 and causes the packing to swell radially and fill the spaces 24. Thereafter the expansive pressure of the packing is exerted between the tapered wall surfaces and the tubes,

'the effect of the tapered wall surfaces being to serve mainly to hold the tubes against creeping and against oscillation due to vibration. Vibration of the tubes When in service tends to produce oscillation of the tube ends, which oscillation, if unchecked, tends to wear or expand the packing andcause leaking between the packing and thetubes. The metal rings 20 restrain the tendency to oscillation and thereby protect the packing. Moreover, the rings seal the outer ends of the packing recesses and retard dryingout of the packing when the condenser is temporarily out of service, so that there is little or none of the customary leaking when the condenser is again put into service.

For the conversion of an existing condenser having the usual internally threaded packing recesses, designated 25 in Figs. 5 and 6, whether the threads extend only part way to the inner ends of the recesses, as in Fig. 5, or extend to the inner ends, as in Fig. 6, the outer end of the packing recess may be reamed out to remove the threads to a sufficient depth to provide a receptacle for the ring 20. If the threads are not removed in the remainder of the recess to produce the structure of Fig. 3, the packing sleeve used, designated 26, is externally threaded to cooperate with the threads of the recess, which then form shoulders retaining the packing in lieu of the tapered wall of Fig. 3. A simple cylindrical packing, as shown in Figs. 3 and 4, is not satis: factory in connection with an internally threaded recess since, even though the packing will swell which the threads do not extend to the bottom of the recess. In such case, the packing sleeve Will expand against the unthreaded wall portion with sealing eifect, irrespective of whether the remainder of the sleeve is threaded or not.

Alternatively, to render the invention applicable without alteration to the tube plate, an externally threaded packing sleeve 26 may be inserted in the packing recess and followed by a tube retaining ring 29*, similar to the ring 29 except that it is externally threaded to cooperate with the treads of the recess. The tube end is expanded in the ring 29 as already described for the ring 29.

The assembling of a condenser constructed according to this invention is extremely simple, quick and easy. When the tubes are in place, the packing sleeves and end rings are easily inserted and cannot be improperly inserted. The expansion of the tube ends is slight and is easily accomplished, as by a sharp blow on an expanding tool inserted in the tube end. The usual expenditure of time and labour in compressing packings by impact or by inserting and tightening packing nuts is entirely eliminated, together with the uncertainty of the result thereof.

It will be seen that in all cases the packing swells against the walls of the packing recesses with retaining effect independently of the end rings and that the tube is held against oscillation at its ends and against creeping by the end rings. The thickness of the rings is greater than the maximum elongation of the tubes so that even if an expanding tube should carry an end ring with it, the ring will not lose contact with the wall of its containing recess and will be drawn back into place when the tube contracts, thereby to serve as sealing means to retard drying out of the pack- Claims directed to the packing member 26 and to the ring members 29 and 29 are presented in a continuation-in-part application Serial No. 177,991, filed August 7, 1950. I

Having thus described m invention, I claim;

1. In heat exchangers, including a pair of tube plates apertured for passage of tubes and tubes passing through said apertures; said apertures being in their outer portions of larger diameter than the tubes to provide packing recesses around the tubes and packing in said recesses; a single rigid metal end ring filling each of the recesses outside the packing, the bores of said end rings being flared and the tubes being expanded at each end into the flared bore portions of the rings, thereby to hold the tubes against creeping.

2. In heat exchangers and the like, tube plates apertured for passage of tubes; tubes passing through said apertures; the said apertures each having an inner portion of tube size and intermediate and outer portions of greater than tube size, the said intermediate portions having mutually facing shoulders; packing in said intermediate portions engageable with said shoulders to be thereby held against displacement in the longitudinal direction of the tubes; said outer aperture portions being of larger diameter than the intermediate portions; and metallic rings filling'said outer aperture portions around the tubes.

3. Structure according to claim 1 in which the packing recesses are internally threaded and the packing and end rings are externally threaded to cooperate with said internal threading.

4. In heat exchanger construction including a tube plate apertured for passage of a tube and a tube passing through said aperture, the aperture being in its outer portion of larger diameter than the tube to provide a packing recess around the tube, and packing in said recess; a rigid metal ring filling the recess outside the packing, said ring having the bore thereof flared in an inner portion of its length and cylindrical in the outer portion of its length, and the tube end portion being expanded into the fiared bore portion of the ring and having sliding contact with the cylindrical portion of the ring bore, thereby to prevent entrance 'of solid matter between the flared surfaces of the tube and ring when such surfaces are separated due to expansion of the tube.

5. In heat exchanger construction including a tube plate apertured for passage of a tube and a tube passing through said aperture,the aperture being in its larger portion of larger diameter than the tube to provide a packing space around the tube and packing in said space; a rigid metal ring filling the space outside the packing, said ring having an inner cylindrical bore portion in which the tube is a sliding fit, an intermediate portion flaring away from the tube and an outer cylindrical portion larger than the tube, the end portion'of the tube being flared to conform to the flared portion of the ring bore and having sliding engagement with the outer cylindrical portion of the ring bore, thereby to prevent entrance of solid matter between the flared surfaces of the tube and ring when the same are separated by expansion of the tube.

6. A packing for heat exchangers including tubes and tube plates having internally threaded recesses around tube ends providing packing receiving spaces, said packing comprising an externally threaded, compressed, water swellable fibre sleeve adapted to be screwed into a plate recess in close engagement with a tube and with the bottom and threaded wall of the recess; and an externally threaded, rigid, metal ring adapted to be screwed into the outer part of a plate recess against said packing and to fill the space between the recess wall and the outer end portion of the tube, outwardly of the packing, the bore of said ring being at its outer end larger than the tube and tapering inwardly to tube size,

. whereby the tube may be expanded into said tapered bore portion to limit movement of the tube in its axial direction.

HUGH n. HERON.

anraannons crrsn The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 510,373 Wheeler Dec. 5, 1893 1,683,393 Morgan Sept. 4, 1928 1,714,703 Walton May 28, 1929 2,298,154 Pennella Oct. 6, 1942 2,420,721 Pennella May 20, 1947 V FOREIGN PATENTS Number Country Date 539,646 Great Britain Sept. 18, 1941 572,487 Germany Mar. 17, 1933

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