US3187810A - Floating-head heat exchangers - Google Patents

Description

June 1965 R. R. HELIN ETAL 3,

FLOATING-HEAD HEAT EXCHANGERS Filed June 10, 1963 INVENTORS RICHARD R. HELIN BY CHARLES A. FENNO ymz United States Patent 5,187,810 FLGA'IING-HEAD IEAT EXCHANGERfl Richard R. Helin, Charleston, and Charles A. Fenno,

Scott Depot, W. Van, assignors to Union Carbide Corporation, a corporation of New York Filed June 10, 1963, Ser. No. 286,694 2 Claims. (Cl. 165-158) The present invention relates to an improvement in floating-head type heat exchangers and particularly to means for providing fluid-tight contact between a floating tube sheet and a head flange in such exchangers. More particularly, this invention is concerned with a special packing joint which provides an effective seal between the shell side and the .tube side of a floating-head type heat exchanger.

The use of so-called shell and tube heat exchangers has gained widespread commercial acceptance. Such exchangers are useful in transferring heat between two liquids, such as for example, in oil refining operation, or between a liquid and a vapor, such as for example in steam power plants. The relative thermal expansions or contractions which frequently result from differences in the temperatures of the fluids flowing through the tubes and the shell, or from differences in the materials of construction of the tubes and the shell, have led to the development and use of the so-called floating-head heat exchangers. In this type of exchanger the tubes are rigidly attached to a stationary tube sheet which is fixed relative to the shell of the exchanger at one end, and are attached to a floating tube sheet at the other end. Hence, in operation, slidable movement obtains between the floating tube sheet and the shell and other fixed parts as the expanding and contracting tubes cause movement of the floating tube sheet, and stress and strains which may otherwise cause wear and failure in the exchanger are therefore avoided.

In the shell and tube heat exchangers, one fluid usually enters the shell at one end and discharges from the opposite side of the shell at the other end, or at the same end, depending upon whether a single-pass or a doublepass arrangement of tubes is employed. The other fluid flows through the tubes from one end and is discharged at the other end (single pass flow), or the fluid may flow through part of the tubes at one end, re-routed through another part of the tubes, in which case such arrangement is referred to as multiple pass flow. In double-pass flow, for example, the liquid enters half the tubes at one end and flows, say from right to left, discharges into a receiving chamber, and is then re-routed to the remaining half of the tubes through which it flows from left to right, and finally discharges from the heat exchanger.

It can be readily appreciated that in this type of heat exchanger, provisions must be made to prevent leakage of fluid from the shell side to the tube side or vice versa. Several such provisions have been suggested and adapted to these exchangers but they are all disadvantageous in one way or another. Most frequently, the floating-head is either bolted or clamped onto the floating tube-sheet and the entire assembly is then mounted in the shell by means of conventional expansion rings or packing joints. This arrangement, however, is expensive, cumbersome and diflicult to install and to disassemble.

Accordingly, this invention comprehends and resides in the discovery of novel means for providing fluid-tight contact between the floating tube-sheet and the head flange portion of the floating head heat exchanger. The novel means employed herein comprises two rings, preferably metallic, with packing materials thereon, said rings being separated by compressible and resilient members, such as, for example, spring washers. These washers are arranged each over one of a multiplicity of circumferentially arranged pins extending longitudinally between the rings, fixed to one ring and slidably movable through aligned holes in the other ring. The pins serve to keep the washers in position.

The novel means employed in the present invention and its adaptation to the floating-head heat exchanger are more readily comprehended with reference to the attached drawings wherein:

FIGURE 1 is a partially sectionalized side elevation of a floating-head type heat exchanger embodying this invention;

FIGURE 2 is an enlarged section showing the details of the floating-head joint of FIGURE 1, and

FIGURE 3 is an isometric free-body view of the two rings showing their relative positions with the washers.

In these drawings, like numerals designate like parts.

Referring to the drawings, there is shown, on the float ing-head side of the heat exchanger, a shell flange 11, gasket 13 and head flange 15, all connected together via bolts 17. Also shown on this side of the exchanger is a floating tube-sheet 19 to which is attached a multiplicity of tubes 21 through which one fluid medium flows. The other fluid medium enters the shell 23 of the exchanger at entrance 25, flows through the shell in contact with the outer surfaces of tubes 21 and leaves the shell at exit 27.

Forming a liquid-tight contact between the floating tube-sheet 19, the shell flange 11 and head flange 15 there is shown a unitary structure comprising two metallic rings 29 and 31 which are connected via twoor more pins 33. These pins are attached at one end to one of said rings, say, ring 31 by welding or any other suitable means, and at the other end the pins are inserted in apertures in the ring 29 through which the pins are free to move in axial direction. A resilient and compressible member 35, such as, for example, a spring washer, is set over each pin, which member is responsive to the relative movements and expansions and contractions at the floating-head joints. Pins 33, apart from their function of connecting the two metal rings, also serve to hold the spring washers in the circumferential array shown.

The unitary structure referred to above is placed in a recess 37 (or a groove, or a notch) specially cut in the flanges, and the remaining space on either side of the rings is filled with packing materials 39 and 41 to fill up the recess. The diameter of the packing materials is preferably slightly larger than the outside diameter of the two metal rings to provide an effective seal as will hereinafter be explained. 1

Rings 29 and 31 can be of metallic or plastic materials capable of withstandingthe compressive forces exerted thereon by the spring washers 3? during the operation of the heat exchanger. The washers 35 may be of any suitable resilient and compressible materials capable of responding to the thermal expansions and contractions resulting from the diflerences in the temperatures of the fluids flowing through the shell and the tube, or to differences in the'materials of construction of the shell and the tubes. The number of the washers can vary depending upon the compressive forces exerted in the floatinghead joint.

In assembling the heat exchanger, when bolts 17 are tightened, gasket 13 is compressed between the surfaces of the shell flange 11 and head flange 15. The compressive forces so set up are transmitted to the packing materials 39 and 41 which packing materials are therefore compressed away from each other as well as against the floating tube-sheet 19, the shell flange 11 and the head flange 15. Thus a fluid-tight contact is provided between the shell side and the tube side of the heat exchanger at the floating-head joint. The compressive forcesrwhichare so ti'ansmit tedto the'pa cking materials are in turn ab-[ sorbed by the spring washers 35 which remain compressed in response. tot these compressive forces and which can .r turnto their normal uncompressed position upon the removal of theseforces. J x V I Thermal expansions and contractions .at the floatinghead joint, resulting from differences in temperature or differences in the materials of construction, as was pre- ,yiously discussed causerelative movement of the floating tube-sheet 19 with respect to. the shell flange 11 and head flange 15. The novel device permits the tube sheet to slide against th e surface s of the shell flange and the ,head flange andat the same time provides a seal between the shell side and the tube side of the exchanger 1 .The device of thisinvention tcvan beemployed in singlepass' as well asmultiple-pass heat exchangers. It otters sim plicity ofinstallation as: Well'as disassemblement of the enchanger and is less costly than the heretofore common types of installations.

What isclaimed isz, a V v V 1. In a floating-head heat exchanger having a flanged tshellvand a flanged head coverfor said shell providing therewith an annular recess at the juncture of the shell -and cover, a tube bundle'in said shell, a floating tube sheet slidably supporting one end of said tube bundle and having an annular surface facing said recess, a fluid tight sealing means disposed in said annular recess comprising a pair of sealing ring members 'spring means beftwleen said sealing ring members resiliently biasing the sa mei apart and into engagement withthe end walls of 7 said annular recess fsaid sealing ring! members eaca being in sealing engagement with the annular surface of said ,shell and a flanged headcover for said shell providing therewithanannular recess atthe juncture of the'f shell and cover, a tube bundle in said shell, afloatingtube'sheet slidably supporting one end of said tube bundle and having an annular surface facing said recess, a fluid-tight sealingmeans disposed in said recess comprising a pair of t oppositely disposed spaced rings, resilient means mounted by and between said rings urging the same axially apart, packing members between eachjof said rings andtheadjacent surfacesof said,recess, ,said pac ing members being of slightly larger diameter than the rings and bearing on thefloating tube sheet and the opposed surfaces of} said recess to provide a seal between the tube sheet and the shell andto permitsaid sealing members tojreact' resiliently responsive to longitudinal movement of said floating tubesh'eet.

narrates'eassythesxaaaa UNITED STATES' PATENTS 93,889 8/69 2 Johnson 27762 6 784,78 3/05 .Getts ,,277\-:- 62 1,662,615 3/28 McNe al 165 s 1,810,286 6/31 MacPhee l65158 CHARIQES SUKALO, Prin zary Exizrhz'ner. KENNETH-W. SPRAGUE, Eidminer.

Claims (1)

1. IN A FLOATING-HEAD HEAT EXCHANGER HAVING A FLANGED SHELL AND A FLANGED HEAD COVER FOR SAID SHELL PROVIDING THEREWITH AN ANNULAR RECESS AT THE JUNCTURE OF THE SHELL AND COVER, A TUBE BUNDLE IN SAID SHELL, A FLOATING TUBE SHEET SLIDABLY SUPPORTING ONE END OF SAID TUBE BUNDLE AND HAVING AN ANNULAR SURFACE FACING SAID RECESS, A FLUID TIGHT SEALING MEANS DISPOSED IN SAID ANNULAR RECESS COMPRISING A PAIR OF SEALING RING MEMBERS, SPRING MEANS BETWEEN SAID SEALING RING MEMBERS RESILIENTLY BIASING THE SAME APART AND INTO ENGAGEMENT WITH THE END WALLS OF SAID ANNULAR RECESS, SAID SEALING RING MEMBERS EACH BEING IN SEALING ENGAGEMENT WITH THE ANNULAR SURFACE OF SAID TUBE SHEET AND THE BOTTOM OF SAID RECESS AND PROVIDING A SEAL BETWEEN THE SAME AND THE SHELL AND SAID SPRING MEANS PERMITTING SAID SEALING RINGS TO REACT RESILIENTLY IN RESPONSE TO LONGITUDINAL MOVEMENT OF SAID FLOATING TUBE SHEET.

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