US2762611A

US2762611A - Tubular heat exchangers

Info

Publication number: US2762611A
Application number: US273924A
Authority: US
Inventors: Paul S Monroe; Krapp Donald; Stanley C Orr
Original assignee: Pfaudler Co Inc
Current assignee: Pfaudler Inc
Priority date: 1952-02-28
Filing date: 1952-02-28
Publication date: 1956-09-11
Anticipated expiration: 1973-09-11

Description

Sept- 11, 1956 P. s. MONROE ET AL 2,762,611

TUBULAR HEAT EXCHANGERS Filed Feb. 2s, 1952. s sheets-sheet 1 P. S. MONROE ET AL TUBULAR HEAT EXCHANGERS Sept. l1, 1956 Filed Feb. 28. 1952' 5 Sheets-Sheet 2 BY Enh/W77;

S WL N N m. r gm l N A m a 6 o Sept. 11, 1956 P. s. MONROE :rAL 2,762,611

TUBULAR HEAT EXCHANGERS IN VEN TORS PA UL s. HvA/Ros,

DONA L D KEA PPe? A770?? EYS -iron or steel tube in a sterilizer unit.

2 ,762 ,6 l Patented. Sept. 1 1 ,11956 TUBULAR HEAT XCHANGRS "Paul S. Monroe, Chatham, N. J.,'and"Donald Krapp, Ver- Imilion, and Stanley C. Orr, Elyria, Ohio; said Donald Krapp, now by change of name 'Donald Kropp, as- "signors'to The Pfaudler Co., Rochester, N. Y., acorl poration of New York Application February 28, 19:52, 'Serial No.273;924

'1 Claim. (Cl. 257-240) The present invention relates vgenerally to the heat exchanger art and is more particularly concerned With a novel tubular heat exchanger comprising a novel Vcombination of elements which alords unique advantages and unique combinations of advantages of substantial'imporf tance.

Although tubularl heat Vexchangersin general have been known and widely used for many years, there has long existed an unsatisfied demand for tubular heat exchangers which could be used for handling fluids corrosiveto the exchangers under operating circumstances. This corrosion problem has persisted down to the timeof the 'present invention, despite the kfact that `the needv for a tubular heat exchanger which Vwould 'fully solve r`the .problem has never diminished. HoWever,this-demand :has'brought forth many etorts by those skilled in the art andhas resulted in a number 'and variety of publications which fail to disclose a solution to ythis problem but serve "to illustrate thel needfor the present invention.

' One'of the priorefforts'at solving-this problem-'involved the vsubstitutionot' a'fused'quartz tube forrau This-fconstruction, however, neverbecame practical 'or VcommercialV and\to the best of our'lcnowledge, no hear-exchanger has Lever been vmade heretofore in accordance-With this proposal.

The expense and d'itliculty'of constructing adevice' offthis "kindl'wouldbe excessiveand itsservice life"'would be *brief duel to the diicu'lty of effectively a'ndlastingly seal- -i-ng the quartzdtube in* lthe 'asSernbly-and also due t-o the forces imposed-upon these' tubes Idue tothermalfcoeicient ditterentialsbe'tween the quartz andlthefmetalelements `engaged andsealed together in the-assembly.

l' In 'accordance with the present invention, the :ditiiculties and shortcomings of the quartzftube heat exchanger con- 'structionv and theother prior art shortcomings-sand ydere- 4li'ctions have been overcome and eliminated. Thus, by

virtue ofthisinvention, a tubular heat exchanger in which one or a plurality of tubes are provided'in a heat `exchanger-shell canbemade withelements Which'cannot be used in accordance with theprior artandwhich en- -able use of the Yheat exchanger for protracted periods unyder conditions Whichfwould rapidly destroy the hereto- 4fore conventional devices. Still further, the devices of this invention may bey easily constructed andv assembled l and also may be readily disassembled for maintenance or repair. As another advantage of the devices ofthe pres- -ent invention, they open an entirely new and Wide range of materials which may be used for best results for various specific purposes. Moreover, this result is 'obtained without in anyway diminishing or sacrificing-sealing effectiveness or necessitating changes in any respect inthe basic lspecifications of heat exchangers as to dimensions, ma-

terials of construction or the routine of the 'assembling and installationl operations.

As 'another advantage of this invention, in a preferred embodiment'where there is the slightest leakage'thro'ugh a tube sheet'at one end or the other of a heat exchanger the'failure ofl the sealing means can be immediatelydetected Withoutthe necessity-of disassembling-.the exchanger to any extentwhatever. Y

Interchangeability oftubes. as to various outside ,diameters and as^to the materialspftube construction is still another unique and important advantage'of -this invention.

Those skilled in the art will gain a further and. better understanding of this invention upon consideration of the detailed description of several exchangers of thisinvention, reference being had to? the drawings accompanyin'gand formingfa part of this specication; in which:

`* Fig. l is a fragment-ary, longitudinal sectional view of a heat exchanger embodying this inventionl'in a preferred form;

Fig. 2 is a'fragrnentary, longitudinal'sectional Viewl of the' device of Fig. l with the tube assemblyanditbe sheets removed to show the b'afe' assembly' Within the exchanger shell;

Fig. 3is' a transverseseeti'onalview taken on 'line`3-'3 Fig. 4is aifragmentary,lorigitudinal Vsectional'vieiv `of -a vjpacketed heat 'exchangershell of this) invention;

V:Fig 5 is a'transversesectionaliviewtaken'onlineSS :Fig: 6 is' a* fragmentarylview fof' another' preferred' type Vofheat exchangerofthisnvenftion, shovvin'g'anen'd porl'tion thereof infdetail;

ghtly the yshell between I`-the-tubes-'and the .tubesheets -'This securing vand sealingmeans generally-includesdeformable 'annuli which surround andv fsealin'glyf bearsagainSt-annular portions of .each 'tube .endpportioni and fagainst annular portions ofl eachtu-be sheet-"adjacent: to lsaidf-tubenend portions.

The.v shell ofthis 1 device lis :suitably generallyfcylindrical yandhas end-'.portions'whichfare open. fGeneralIyuc'ayIindrical anged' bonnetsare clamped orotherwisefzsecured lto each "end'of the'fshellftolserve asheaderimeansfor delivering fluid into the tubes of the as'semblyandrWi'th- "drawing it therefrom. r`Any vsuitable-clarnp `meansilrnay vbe used for: securing the1bonnets 'tot thefshell-y and the'fshell may be constructed of virtually any desired-material having- -the strength qualities and' corrosion-resistance required for the intended use. Insome'instances''aglass-linedE i'ron lor steel shell may be 'employed-where,-for.instanceyacid resistance is va primary consideration.

In reference particularly to the heat exchangerillustrated in-Figs. l, 2 and -3, thisapparatus comprises an elongated, generally cylindrical shell 1'0 vvhich-isopen -at each end and which is providedwith huid inlet and tended for use, for example, in a chemical plant in the handling of acids which are corrosive to ferrous metals, such as hydrochloric acid and sulphuric acid.

This heat exchanger comprises seven tubes 19 arranged in three parallel-tiers, as indicated in Fig. 3, these tubes being longer than shell including end flanges 14 to extend through the shell and project from the ends thereof and thus facilitate assembly with the tube sheets and the bonnets of the assembly subsequently to be described. Tubes 19, like shell 10, are suitably of steel which is protected from contact with corrosive iluids within the shell by means of glass coatings covering the outer surfaces of the tubes.

For the purpose of directing and controlling the flow of heat exchange fluid from shell 10 from inlet port 11 to outlet port 12, a baille assembly B is provided within the shell as illustrated in Fig. 2. Battles 20 of assembly B are of thin section and generally semi-circular and they are arranged to provide a tortuous passage for fluid between the said ports, adjacent baffles being spaced apart but in effect partially overlapped. Baffles 20 are secured in place against gravity and pressure exerted by heat exchange fluid ilowing through the shell in contact with the tubes by means of tie rods 22. Each of these rods serves to join three baffles together. Bafiles 20 are provided with transverse apertures through which tubes 19 extend. The tie rods are assembled and held in place with nuts 23 screwed on threaded ends of the rods to atord adjustability and provide a rigid structure providing the desired flow characteristics in heat exchange fluid. The end rod 22 of bale assembly B extends through the end of shell 10 for engagement with a tube sheet thereby to stabilize the assembly and prevent it from shifting lengthwise of the shell in use. Baiiles 20, tie rods 22 and nuts 23 are all suitably of material which will be resistant to the uid to be run through shell 10 in contact with the outer surfaces of tubes 19. We have found, however, that when these items are made of Karbate which is a compressed, bonded rigid graphite-amorphous carbon mixture manufactured and sold by the National Carbon Co., or Haveg which is a compressed and bonded mixture of phenolformaldehyde-type resin and asbestos manufactured and sold by Haveg Corporation, they are generally satisfactory for a wide variety of purposes, being resistant to most organic and inorganic acids to which glass is resistant.

A pair of tube sheets 25 are provided to close the ends of shell 10 and while they are of steel, these elements are glass-covered, as indicated at 26, for acid resistance.

These tube sheets have transverse openings 28 through which the ends of tubes 19 may extend, as shown in Fig. l without engaging said tube sheets. The radius of sheets 25 is substantially the same as the radius of end anges 14 to facilitate the liquid-tight attachment of the tube sheets to the shell.

Packing material of any suitable type resistant to the acid or other corrosive substances to be contained in the shell is provided in the form of a pair of thin, ilat rings 29 of a radius corresponding substantially to flanges 14. Tube sheets 25 are assembled with these rings 29 disposed between them and the end anges of the shell to prevent leakage of lluid from the shell between said sheets and anges.

The means for sealing the tubes in assembly with the tube sheets comprises in this Fig. 1 heat exchanger an annular body 31 of packing material of the required anticorrosion characteristics. Annulus 31 in each instance is of internal diameter conforming substantially to the external diameter of tubes 19 so that when these rings are slipped on the tubes they sealingly grip said tubes. In transverse section rings 31 are of trapezoidal shape to assure their iirm sealing engagement with not only the tube in each instance, but with tube Asheet 26, the base of of the trapezoidal section bearing against an annular portion of the tube whilethe sloping sides thereof bear against the tube sheet and against retaining means including a portion of a bonnet member 35.

Bonnet 35 is of generally cylindrical shape and has a tube sheet 36 opposed to a tube sheet 25, an outer wall 37 spaced therefrom and provided with a port 38 for delivery to or discharge of iluid from a pipe header chamber 39 within the bonnet. Tube sheet 36 has seven transverse openings for registry with openings 28 in the tube sheets to receive the end portions of tubes 19 and these inner wall openings are threaded for a purpose to be described. This bonnet inner wall in addition is of substantially the same diameter as the tube sheets and in the illustrated assembly this portion of the bonnet is disposed closely adjacent to the outer side of a tube sheet, being spaced therefrom by means of a ring 40 of packing material of substantially the same diameter as packing ring 29. Ring 40, however, is provided with a slot 41 in its lower portion to allow for drainage from the heat exchanger of any iluid leaking through the tube sheets or inner wall 36.

Rings 31 are retained in position, as indicated above, by hollow nuts 44 screwed in the openings in tube sheets 36 of the bonnets, these nuts having inside diameters at their inner ends greater than the outside diameter of the tube ends. Thus, `tubes 19 are received in the inner ends of nuts 44 without engaging the nuts but the nuts are rmly engaged with the trapezoidal packing rings 31 and are in addition, readily removable and are adjustable to make allowances for variations in packing ring shape and dimensions.

In the apparatus of Fig. l, each of the bonnets is provided with a bulkhead 46 extending axially of the bonnet and thereby dividing chambers 39 into two parts. The purpose of this is to provide for flow of uid through the tubes in certain predetermined sequence as indicated in the drawings.

The Fig. 1 assembly is held together by means of eight adjustable clamps 50, metal rings 51 being welded to the outer peripheral portions of end flanges 14 and to the bonnet tube sheets 36 to provide means for anchoring these clamps in position to hold the assembly together.

Shell 53 illustrated in Fig. 4 is basically similar to shell 10, but is jacketed over most of its length between the inlet and outlet ports 54 and 55. The provision of jacket I is desirable in the case where additional condensing surface is required for increased efficiency of the heat exchange operation or for increased capacity of the heat exchanger. Jacket J comprises a cylindrical portion 57 of internal diameter substantially greater than the outside diameter of shell 53 whereby a chamber 58 is dened between these two elements for the ow of heat exchange iiuid in contact with the shell outer surface. The ends of cylinder 57 are closed, rings 59 being welded to shell 53 and to this cylinder, and inlet and

outlet pipes

60 and 61 are formed on cylinder 57 for delivery of heat exchange iluid into and removal of such iluid from the chamber 58 through openings provided for this purpose in the said cylinder near its ends.

Referring to Fig. 6, the heat exchanger shown comprises a shell 10 described above and a tube sheet 65 having transverse apertures 66 of reduced diameter at their inner ends and increased diameter in their mid-sections and at their outer ends. Thus tubes 19 cooperate with sheets 65 to deiine passages through these sheets which are constricted adjacent to the inner sides of the sheets -but are enlarged toward the outer sides thereof, the tubes, however, being spaced from the sheets at all points. The purpose of this unique tube sheet structure and tube sheet-tube relationship is to provide for maximum sealing eifect in high-pressure and long-service operation. Packing P thus is disposed in these passages to bear against an annular shoulder 69 defined in tube sheet opening and engages opposed annular portions of the tube sheets and the end portion of the tubes extending therethrough. Preferably, as shown a plurality of deformable packing ring elements 70 are located in these passages in huid-sealing engagement with the tubes and the tube sheets and are retained in this position by means of retaining nuts 44 screwed into inner wall 71 of a bonnet 72.

Bonnets 72 are basically similar to bonnets 35 but have fluid inlet or discharge ports 73 in their side walls instead ot their end walls and therefore pipe connections 74 extending radially instead of generally axially of shell 10. The tube sheets 65 are spaced from and sealingly related to flanges 14 and inner wall 71 by means of gasket rings 67, which unlike gaskets 40 are not slotted.

The Fig. 7 assembly differs from those described above in that anged end portion 77 of its shell 76 extends across the end of the shell and is provided with a plurality of transverse openings 79 through which tubes $0 of the assembly extend without engaging the said flange portion. Also in this Fig. 7 apparatus, neither the shell, the iiange portion 77, nor tubes 80 are provided with a glass protecting coat or other special corrosion-resistant covering, but the tubes and tube sheet 82 and communicating vessel 90 are composed of corrosion-resistant metal. Thus, in this Fig. 7 assembly the shell 76 is not exposed to the corrosion fluids owing in contact with the tubes, or in other words, it is the tube-side rather than the shellside which must be corrosion-resistant, unlike the assemblies of Fig. l or 6. Tube sheet 82 has transverse openings 83 in register with openings 79, the diameter of these openings 83 being greater than the outside diameter of the tubes to provide for clearance between the tubes and these elements in accordance with this invention. The tubes are sealed in position and assembly with the tube sheet and the shell by means of deformable annuli S5 which bear against annular portions of the ends of the tubes and against the outer surface of the shell frange discs and against the inside surface of the tube sheets. it may be noted that unlike the arrangement in Fig. 1, in accordance with the Fig. 7 construction, sealing rings 85 -are disposed to the inside of the tube sheet rather than to the outside thereof. However, as in the Fig. l assembly and more noticeably in the Fig. 6 assembly, these rings are disposed between opposed annular portions or the tube sheets and the tube end portions. The tube sheets in the Fig. 7 embodiment thus function as means for securing and supporting the tubes in place and for sealing the tubes and tube sheets together by virtue of the fact that in cooperation with shell flange discs 77 the tube sheets hold the sealing annuli firmly in location against the tubes.

In this Fig. 7 assembly, the bonnet is a fabricated cylindrical body 90 which is open at one end and is provided with a ange 91 and at its other end has a pipe connection 94 for delivery of uid into or receipt of tuid from the tubes of the apparatus.

Tube sheets 82 and the bonnets 90 are held together with shell 76 by means of a plurality of nuts 96 and bolts 97 the bolts extending through registered openings in the peripheral portions of flange 91, the shell ilange and the bonnets and through an outer portion of the tube sheet, nuts 96 being screwed on the threaded ends of bolts 97 to establish and maintain the desired pressure on a flat ring 99 or packing material disposed between the outer sides of the tube sheets and the opposed inside portion of bonnet flange 91.

Instead of using glass-lined tubes in the heat exchangers of this invention, tubes of glass, noble metal-clad tubes, tubes of porcelain, Duriron, Hastelloy and similar metals, alloys and ceramic materials, may be ernployed to realize the advantages of this invention set forth above.

Similarly, as indicated above in reference to Fig. 7, the bonnets, tube sheets and other parts such as packing retaining nuts may be of glass or may be glass-lined, noble metal-clad or other special type in order to realize the advantages of this invention set out above.

Having thus described the present invention so that others skilled in the art may be able to gain a better understanding and practice the same, we state that what we desire to secure by Letters Patent is defined in what is claimed.

What is claimed is:

A heat exchanger tube and tube sheet assembly comprising a tube sheet having a transverse aperture of enlarged diameter at one end and reduced diameter at the other end and an annular abutment between the ends of the aperture, a tube extending through said aperture in spaced relation to the tube sheet and cooperating with the tube sheet to define an annular chamber, packing in said chamber comprising a deformable annulus surrounding a portion of the tube in said tube sheet and bearing against opposed portions of the tube and tube sheet, a support wall spaced from the tube sheet and opposing the outer side thereof, and a packing gland threadably engaged with said support wall and having an annular end portion projecting into said chamber and pressing the packing into sealing engagement with the tube sheet and tube within said chamber, said annular end portion of the packing gland having an inside diameter approximating the minimum diameter of the tube sheet aperture and being in axial and radial spaced relation to the end of the tube extending through the tube sheet whereby the tube is held in fioating spaced and sealed relation to the tube sheet for limited relative axial and radial movement.

References Cited in the tile of this patent UNITED STATES PATENTS 1,183,312 Martin May 16, 1916 1,892,377 Bergskaug Dec. 27, 1932 1,948,550 Voorheis Feb. 27, 1934 2,394,402 Pennella Feb. 5, 1946 FOREIGN PATENTS 273,605 Great Britain Nov. 12, 1926 549,431 Great Britain Nov. 20, 1942