US1990251A - Heat exchange apparatus - Google Patents

Description

Feb. 5, 1935. I J POTTER 1,990,251

HEAT EXCHANGE APPARATUS Filed April 17, 1933 3 sheeis-sheet 1 ho Q Mg}? l? III wrmsgssas: m. m g INVENTOR 4M JOHN HPo'rTEFe. CLW M ATTORNEY Feb. 5, 1935.

J.'A. POTTER 1,990,251 HEAT EXCHANGE APPARATUS Filed April 17, 1933 5 Sheets-Sheet 2 w masses: 4M

i INVENTOR 6- I v JOHN APQTTER.

BY I Q,/5 flM-p4 ATTORNEY Feb. 5, 1935. J. A.YPOTTER 1,990,251

HEAT EXCHANGE APPARATUS 7 Filed April 17, 1933 y 3 Sheets-Sheet 3 v ITNE'SSESI INVENIOR A v v JOHN HJ OTTER (2 0358 ATTORNEY Patented Feb. 5, 1935 srss mica-51 Westinghouse Electric 8; Manufacturing Compa y, East Pittsburgh, Pa, a corporation of Pennsylvania Application April 17, 1933, Serial No. 666,5 l

6 Claims.

My invention relates to heat exchange apparatus of the surface or tubular type, and more particularly to those wherein fluid circulating tubes extend longitudinally through a tubular shell and connect a fixed header construction closing one end of the shell and a floating or movable header construction contained in the other end of the shell.

As is well known, the purpose of this type of apparatus is to transfer heat from one fluid to another fluid, one fluid being circulated through the interior of the tubes andthe other through the shell and contacting with the exterior surface of the tubes.

The purpose of the floating head type of heat exchanger is two fold, first to permit removal of the tubes and tube sheet lengthwise of the shell, and a second, to provide for relative expansion of the tubes and shell which may be due either or both to different coefiicients of expansion of the metals of which the shell and tubes are made, and to the difference in temperature between the fluid passing through the tubes and the fluid passing through the shell.

It is recognized that the most eflicient operation in heat-exchangers is obtained wherein the tubes come closer to filling the entire interior of the shell, the fluid passing through the shell having a tendency to travel the line of least resistance which is through spaces between the tubes. In order that the floating tube sheet be removed through the shell, the diameter of the tube sheet must, of course, be less than that of the shell. Also, in order that the tubes fill as near as possible the interior of the shell, openings for the tubes in the tube sheet must be placed as near as possible to the periphery thereof. The securing means for the floating tube sheet and its header must, therefore, require the minimum of surface on the periphery of the tube sheet.

In apparatus of this character heretofore known to me, it is common practice to provide partitions in the headers to divide the latter into two or more chambers so as to cause the fluid in the tubes to pass through the shell a plurality of times before leaving the apparatus. For example, partitions may be placed in the headers so that the fluid first enters a chamber in'the fixed header and passes through a firstfs'et of tubes to a chamber in the floating header cbmmunicating with the ends of the first set'and also with the ends of a second set of tubes, returned by thesecond set of tubes to a second chamber in the fixed header which also communicates with a third set of tubes through which the fluid flows to a second chamber in the floating header which latter is also connected to a fourth set of tubes through which the fluid is conducted to a third chamber in the fixed header and from there to an outlet. This type of construction is known as the four-pass type because the fluid in the tubes passes through the shell four times before it leaves the apparatus.

From the above, it will be seen that for a fourpass type, two partitions are necessary in the fixed header to provide the three chambers and one partition in the floating header to provide the two chambers. More specifically, the present invention has to do with apparatus of this type wherein two or more chambers are provided in the floating header. Hence, the present invention is applicable to heat exchangers having four or more passes.

It has also been suggested heretofore to provide a longitudinally extending baflie in the shell so as to provide for a more intimate contact between the fluid in the shell and the exterior of the tubes. Heretofore in heat exchangers having a floating head and a horizontal baflie, the common practice is to provide a battle which is removable with the tubes and tube sheet. however, does not operate as efliciently as is desired, due to the inability of sealing effectively the space between the longitudinal edges of the baffle and the shell, and this results in the fluid in the shell short circuiting or passing around the edges of the baflie instead of following its proper path through the shell. A further disadvantage of this type of construction, which is also true of heat exchangers not having the longitudinal bafiie, is that it often develops that the temperature of certain of the tubes is much greater than that of other tubes, thereby .causing the hotter tubes to elongate more than the cooler tubes and placing strains on the movable tube sheet and the joint between the tube ends and movable tube sheet.

Therefore, a more specific object of the present invention is to provide a multiple-pass heat exchanger of the floating-head type wherein the plurality of chambers are provided in the fioating head by dividing its tube sheet into separate and independently movable sections with a separate cap or header secured to each section of the tube sheet by a means which permits free relative movement between the sections and at the same time provides for the placing of tubes closely adjacent the periphery of the tube sheet so as to effect the desired distribution of tubes in the shell.

These and other objects will be effected by my invention as will be apparent from the following paratus taken on the line IIIIII of Fig. 1;

Fig. 4 is a transverse sectional view taken on the line IVIV of Fig. 1 and. showing the partitions in the fixed header;

Fig. 5 is an end view of the floating-head end of the apparatus with the shell cover removed;

Fig. 6 is a detail view of the clamping rims;

Fig. '7 is a fragmentary sectional view taken in the same plane as Fig. 1 and showing the floating head end of the apparatus, certain of the parts being expanded to indicate their manner of assembly;

Fig. 8 is a view similar to Fig. 7 showing a modified form of my apparatus; and,

Fig. 9 is a view similar to Fig. 5 showing the -modifled construction of Fig. 8.

Referring now in detail to the -construction illustrated and particularly to Figs. 1 to 7, inelusive, the reference numeral 10 indicates a cylindrical shell which may be formed as a seamless tube, and is provided at the opposite ends thereof with flange portions 11 and 12 welded to the outer surface ofthe shell and is divided longitudinally into a pair of chambers 13 and 14, respectively, by a longitudinal baille 15 extending for the width of the shell and welded along its edges to the shell as indicated at 16 (see Fig. 2). The shell 10 is provided with an inlet opening 1'? for the fluid which passes therethrough and contacts with the exterior of the tubes as will presently appear. An outlet opening 18 is provided at the end of the shell adjacent the inlet opening and provides for the discharge of p the fluid from the shell.

A plurality of. tubes 19 extend'longitudinally through the shell as shown and connect a fixed header 20 at one end of the shell with a floating header 21 at the other end. Thefixed header comprises a body 22, tube sheet 23, end cover 24. The tube sheet 23 is provided with openings 25 I withinwhich the adjacent ends of the tubes are fixed. The body 22 is provided at one end with a flange 26 which engages the outer surface of the tube sheet 23. The header 20 is secured to the end of the shell by bolts 27 passing through registering openings in the flange 26, tube sheet 23, and flange 11. The opposite end of the body 22 is provided-with a second flange 28 to which is secured by suitable bolts 29 the cover24. The

interior of the header is divided into three chambers, 32, 33 and 34, by a pair of partitions 30 and.31(see Fig. 4). An inlet opening 35 is provided in the body 22 and communicates with the chamber 32 and an outlet opening 36 isalso provided in the body and communicates with the chamber 33. 55.

The opposite end of the shell 10 is closed by an enlarged cylindrical end portion 37 having a flange 38 welded to the open end thereof. The

I flange 38 abuts the flange 12 on the end of the shell and is secured thereto by suitable bolts 39.-

- The cylindrical end portion 37 is of larger diameter than the shell 10 so as to provide an en- 40 which is of smaller diameter than that of theshell 10 to permit it's withdrawal through the' shell with the tubes. The tube sheet 40 is provided with openings 41 within which the ends of the tubes are rigidly secured. The tube sheet 40 is divided into a plurality of sections 42 and 43 which are semi-circular as indicated in Figs. 3 and 5. A cap or cover 44having a peripheral rim portion 45 is secured to the section 42 at the side thereof opposite the tubes and provides therewith a chamber 46 communicating with the ends of a portion of the tubes 19. The cover 44 is secured to the section 42 by means of a semicircular clamping rim 47 (see Figs. 3 and 6), engaging and overlapping the arcuate portion of the peripheral surface of thesection 42 at the side opposite to the cover 44, and bolts 49 extending through registering openings in the rim '47 and cover 44. Bolts 49a serve to secure directly the second clamping rim 51 and bolts 52 in the same' manner as just described in connection with the cover 44 and section 42. Bolts 52a secure the cover 50 and section 43 along their straight sides. The cover 50 and tube sheet section 43 definea chamber 53 communicating with the ends of a portion of the tubes 19. In Fig. 7, I haveshown the cover 50, rim 51 and end portion 37 as expanded so as to more clearly illustrate the manner of attaching the covers to their respective tube sheet sections.

The baffle '15 lies in the same planeas the line of division between the tube sheet sections 42 and 43 and, as shown, may extend between the sections.

From the above, it will be apparent that, by removing the end portion 37 and the covers 44 and 50, and rim portions 47 and 51, the floating tube sheet 40 may be withdrawn lengthwise through the shell, the section 42 passing through the chamber 13 and the section 43 passing through the chamber 14.

In order to provide more intimate contact 1 successive passages 63 in the chamber 13, through openings 66 in the baffle 15 and then through successive passages 63 in the chamber 14 to the outlet opening 18. The arrows in Fig. 1 show the passage of the fluid through the shell.

Thebaffles 60 and 61 are tack-welded to longitudin'ally-extending spacing rods 67 so as to assure; tgeir relative position in the shell. The bafiles' 6 removed with the tubes.

The fluid which flows through the tubes 19 is admitted through the inlet opening 35 to the chamber 32 in the flxed header 20 and flows through a first set of tubes which communicate with the chamber 32, to the chamber 46 in the floating header 21. The chamber 46 is alsoin communication with a second set of tubes and the fluid is returned thereby to the chamber 34 and 61 and the spacing rods 67 are Communication 1,990,251 ,in the fixed header 20. The fluid is returned .14, the fluid passing from chamber 13 to chamber 14 only through the openings 66. Furthermore, by dividing the floating tube sheet into sections with the line of division in the same plane as the bafile, the tubes and tube sheet sections may be readily removed without disturbing the baflie. The rim clamping feature for securing the covers 44 and 50 to their respective tube sheet sections 42 and 43 provides for the placing of the tubes closely adjacent the outer periphery of the,

tube sheet and consequently for the proper distribution of the tubes with respect to the shell. A further and very importantfeature of my apparatus is in the fact that each tube sheet section and its respective cap is freely movable longitudinally of the shell without interfering with the other section and cap. This latter permits free ,relative expansion between the tubes secured to one section and those secured to the other section and thereby reduces the degree of strain placed on the tube sheet and the joints between the tube sheet and tubes. This feature is especially advantageous in constructions employing a longitudinal baffle, as there is usually a large difference in temperature between the fluid entering the shell and contact with the tubes at one side of the bafile and the fluid leaving the shell and contacting with the tubes at the other side of the baflle.

In Figs. 8 and 9, I have shown a slightly modified form of construction for the floating end.

As will be observed, I provide a tube sheet '70 divided into sections '71 and 72 and these sections are closed respectively by covers 73 and 74. The covers 73 and 74 have arcuate portions 85 similar to the covers of the previously described modification, but are formed differently along their adjoining sides in that they are provided with serrated portions 75 and '76 which interfit with one another. The arcuate edges of the covers '73 and 74 are secured. to their respective sections 71 and 72 by means of arcuate rims '77 and '78 and. bolts 79 in somewhat thesame manner as the corresponding parts of the previously described modification. The adjoining edges, however, of the sections 71 and 72 are secured to the diametral portions "of their respective edges by means of bolts 80 extending through holes 81 provided in I their respective caps, and provided'hook portions 82 engaging the side of the sections opposite to the caps, the bolts serving f to clamp the sections to thecap. By reason of this construction, the

'bolts 80 may be arranged in. a straight line, as

shown in Fig. 9, and, therefore, a minimum portion of the surface of the tube sheet sections is required for the securing of the caps thereto.

While I have shown my invention in several forms, it will be obvious to those skilled in the art that it is not so limited, but is susceptible of various other changes and" modifications, without departing from the spirit thereof, and I desire, therefore, that only such limitations shall be placed thereupon as are imposed by the prior art or as are "specifically set forth in the appended claims.

What I claim is:

i. In heat exchange apparatus of the fioatinghead type, the combination of a tubular shell; a tubular end construction having larger ,transverse dimensions than the corresponding dimensions of the shell; a tube bundle in the shell; a

tube sheet for one end of the tube bundle and respective section so as to provide for relative longitudinal movement of sections; eachmeans comprising a rim element engaging and overlapping at least a part of the outer periphery of its respective section at the side opposite the respective cap, and bolt means connecting the rim and cap, the adjoining edges of said caps being formed as interfitted serrations and; for this portion of the capsa substantially straight line of bolts being used for securing directly the cap to its respective tube sheet, the arrangement being such that alternate bolts secure together the same tube sheet section and its respective cap.

2. In heat exchange apparatus of the floating head type, the combination of a tubular shell having a baffle fixed thereto and extending longitudinally thereof; a bifurcated tube bundle arranged in the shell with portions thereof disposed at either side of said baflie; the portions of said tube bundle having segmental tube plates such that opposed chordal edges thereof are disposed at either side of the baflle with the arcuate peripheral edges thereof capable of being moved longitudinally within the shell; a segmental head construction for each segmental tube plate and embodying a header comprising a segmental rim portion having its ends joined by a chordal rim portion with a plate joined to the rim portions to form an enclosure, said arcuate and chordal rim portions being adapted to fit against the arcuate and chordal margins of the associated segmental tube plate, an arcuate ring section adapted to align with the arcuate rim portion with the arcuate edge of the associated tube plate segment therebetween, an arcuate series of bolts for connecting the arcuate rim portion and the arcuate ring section so that the latter may bedrawn together to grip the arcuate edge of the tube plate segment, and a chordal series of bolts extending through the chordal'rim portion and threaded to the chordal margin of the associated tube plate segment; and means connected to one end of the shell and forming an enclosure for the head constructions providing for movements of the latter incident to expansion and contraction of the tube bundle. i

'3. A heat exchanger having at least two shell passes and at least two tube passes in each shell outlet chamber, a fixed tube sheet adjacent said header construction, a longitudinally-extending bafile fixed in the shell and forming a partition between two shell passes, tubes. extending longitudinally in said shell passes and secured at one posed on the inner side of the arcuate marginal portion of each floating tube sheet section, means for securing the arcuate ring sections to the respective arcuate rim portions of said covers with the arcuate edges of the floating tube sheet sections secured therebetween, means for securing said chordal rim portions of said covers and the chordal marginal portions of said floating tube sheet sections together, and a closure for said other end of the shell, said inlet, outlet, and reversing chambers being arranged to provide an even number of tube passes in each shell pass.

4. A heat exchanger as specified in claim 3, wherein each segmental cover is formed on a radius greater than the radius of the interior of the shell.

5. A heat exchanger as. specified in claim 3, wherein the means for securing said chordal rim portions of the covers and the chordal marginal 7 portions of the floating tube sheet sections together comprises bolts threaded directly into said tube sheet sections. v

6. A heat exchanger having at least two shell passes and at least two tube passes in each shell pass, and comprising a shell, a fixed header con- "struction at one end thereof providing an inlet chamber, a reversing chamber and an outlet chamber, a fixed tube sheet adjacent said fixed header construction, a longitudinally-extending baffle fixed in the shell and forming a partition between the two shell passes, tubes extending longitudinally in said shell passes and secured at one end to said fixed tube sheet, a floating tube sheet section secured to the other end of the tubes in each shell pass, said floating tube sheet sections being of a size to permit longitudinal movement thereof through the respective shell passes, a cover, secured to each floating tube sheet section to form therewith a reversing chamber and having rim portions engaging the outer sides of the margin portions of the tube sheet section, a retaining member extending along the inner side of themarginal portion of each floating tube sheet section which is adjacent the shell, bolts ex tending through said retaining members and the respective rim portions of said covers for securing the same together with the edges of the floating tube sheet, sections secured therebetween, bolts extending through the rim portions of said covers which are adjacenteach other and threaded directiy to the respective marginal portions of the floating tube sheet sections'for securing the same together, and a closure for the other end of the shell, said inlet, outlet, and reversing chambers being arranged to provide an even number of tube passes in each shell pass.

. JOHN A. POTTER.

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