US2411097A - Heat exchanger - Google Patents

Description

ANew., `12, 41946.

S. KOPP HEAT `ExcHANGER Filed March 16,l 1944 2 Sheets-Sheet l 69 INVENToR Sigmund Kopp S, KOPP HEAT EXCHANGER Filed March 1e, 19:14` 2 sheets-sheet 2 v ,lll

1NvENToR f Y l Sigmund Kopp ATTORNEY raffinati Nev. 152, 1946 HEAT EXCHAN GER Sigmund Kopp, Glen Rock, N. J., assignor to American Locomotive Company, New York, N. Y., a corporation of New York Application March 16, 1944, Serial No. 526,682

1 Claim. 1

This invention relates to heat exchangers and more particularly to means for preventing extreme temperatures in the tube sheets, or other parts, of the exchanger.

In certain types of heatexchangers the tube sheets, or other parts thereof, may be exposed to extreme temperatures, either extremely high or extremely low. In designing such an exchanger, means should be provided for moderating these extreme temperatures. For instance, in a heat exchanger adapted for heat exchange between hot luidcatalyst mixture and cold oil, wherein the hot lluid passes through tubes, it will be found that the tube sheets for the tubes will be subjected to extremely hightemperatures due to the huid-catalyst mixture. This high tube sheet temperature, if not counteracted, will result in distortion of the tube sheets and injury thereto.

It is. known that distortion of heat exchanger parts, due to extreme temperatures, may bev -chromemolybdenum steels may be employedv where high temperaturesare encountered.` HoW- ever, where such metals are not available, `or the costis'prohibitive, other means must be sought so that relatively inexpensive and available metals may be used `andprotected to withstand the aforesaid vextreme temperatures. Thus, Where low carbon steel is employed, injury from extreme 'temperatures may be minimized or avoided `byi'proper. insulation of the endangered parts, or means maybe provided to cool hot surfaces, or heat cold surfaces, as the case may be.

The ypresent invention is directed' toward providing means for cooling extremely hot surfaces, or heating extremely-cold'surfaces, of parts of ahe'at exchanger exposed to extreme temperatures, to the end that a cheap and plentiful metal 'such' asjlow carbon steel, may be employed in the manufacture of these parts'. The invention is not conned, however, to means forrso heating or coollngfany particular kind of metal as the means, obviously, can be so employed with various kinds of metals, wherever the need arises.

' An objectof thepresent invention is to provide avheat exchangerhaving means for cooling surfaces of parts thereof exposed to .extremely high temperatures, or'for heating surfaces or parts thereof exposed to extremely low temperatures.

Other and further objects of this invention will appear from the following description, the

accompanying drawings land the appended claim.

Referring to the drawings forming a part of this application, Figure 1 is a foreshortened vertical central section of a heat exchanger embodying the present' invention, parts being shown in full; Fig. 2 is a section on the line II-II of Fig. 1, the tubes being indicated by circles; Fig. 3 is a Vforeshortened,section on the line III-,III of Fig.

4, showing la'hbther embodiment of the invention, parts being shown in full and parts being omitted; Fig. 4 is a section on the line IV--IV of Fig. 3, parts being broken away, some only of the tubesl being shown and indicated by circles; Fig. 5 is a section on the line V-V of Fig. 3, parts being broken away, some only of the tubes being shown and indicated by circles; Fig. 6 is a section on the line VI-VI ofFig. 3, some only of the tubes being shown andindicated by circles; and Figs. '7 and 8 show a further embodiment of the invention, Fig. 7 being a View similar to Fig. 5 and Fig. 8 being a section on the line VIII- VIII of Fig. 7, showing a portion of the structure of Fig. 7.

The heat exchangers shown in the drawings are types suitable to effect heat exchange between a hot fluid, such as a ue gas catalyst mixture, flowing through the tubes, and a cold. iluid,l

`when employed with the hot fluid-catalyst mixture in the tubes and the cold oil in the shell, it being believed that the invention will be clearly i understood from such a description.

Referring to Figs."12`of the drawings, a heat exchanger, 'indicated' generally by the reference numeral l, embodying the present'invention, is shown therein. Assurningfor` the purposes of description, that it is vertically disposed, as shown, it includes a top tube sheet 2,.:a bottom tube sheet 3, a shell 4 spanning and Welded to the tube sheets, a top header or cap 5 bolted to v the sheet 2 and provided with an outlet nozzle 6, and a bottom header or cap 1 bolted to the sheet 3 and provided with an inlet nozzle 8. Gaskets are provided between the tube sheets and vcaps in the usual manner. 'A plurality of tubes 9 extend between and have their ends secured in orices in the tube sheets and open into the interior of the caps. The tubes are preferably tube wall on the shell side.

3 staggered so that the fluid ilowing thereacross must flow in a circuitous path between the tubes,

no straight-through path in the direction of I'low between the tubes being provided.

The shell contains a plurality of staggered horizontal bailles I0, provided with orifices for the tubes and secured to the shell for causing shell uid to flow through the shell crosswise of the tubes in a circuitous passage. An inlet nozzle I I opens into the shell at the top a short distance below the tube sheet 2 and an outlet nozzle I2 opens from the shell at vthe bottom a short dis- V tance above the tube sheet 3.

It is contemplated that the shell fluid and the tube luid will be in counterflow. For instance,

`hot fluid (fluid-catalyst mixture) .may enter the cap 1 through the nozzlel8 from a suitable source of supply, such as a fluid-catalyst mixture separator, flow upwardly through the tubes 9 -into the cap 5 and leave the exchanger through the nozzle 6 which may be connected to a fluid-catalyst mixture regenerator. Cooler fluid (oill' may venter the shell through the nozzle II and leave passing through the tubes and the maximum temperatures that they reach will depend 'upon the fluid-catalyst mixture to the tube wall on'the tube side and to the o il or cold fluid from the By correctly proportioning the size of the tubes and shell, the number of tubes employed, the shell cross-sectional area closed off by each of the bailles I and the distance between the battles I0, these maximum tube temperatures may be held within permissible limits. Y

The temperature of the shell wall will be lower than the tubes, as the shell is lled with a lower temperature fluid than-the tubes. This temperature may similarly be controlled to some extent by the same proportioning mentioned in regard to controlling the temperature of the tubes. Moreover, if desired, the outer face of the shell, or any desired portion thereof, may be insulated (not, shown) in any well-known manner to prevent loss of heat through the shell wall.

Furthermore, the tube sheets 2 and 3, which are of relatively thick metal compared with other parts of the exchanger, are subjected to extreme heat as they are in contact with the hot fluid in the caps and 1 respectively, and further receive heat from the tubes which are secured in the tube sheets. It is therefore desirable to provide means to limit the maximum temperatures of the tube sheets.

'I'he means employed to partially cool the tube sheet 2 is a baille I3 shown in Figs. 1 and 2. 'This baille I3 includes a thin horizontal plate I4, provided with orifices for the tubes, spaced a short distance below tubeA sheet 2 and having a straight edge I5 extending across the shell and leaving a portionof the shell at one side unbaIlled. At the other side the plate I4 has al curved edge I6 spaced from and concentric to the adjacent Wall portion of the shell. 'I'he plate I4, at its remaining sides, may be welded to the shell. Acurved vertical plate I1 is welded to the plate I4 at the edge I3 and extends downwardly slightly below theI nozzle Il and is connected to the shell at its vertical edges by walls I1". Walls I1 and plate thetube sheets for cooling same.

A similar baille I3 is provided adjacent tube,

sheet 3 and similar parts thereof are designated by similar reference numerals with an accent added, no further description of same being deemed necessary. Y

A plurality of seal strips or fins I9, extending between the plate I4 and the tube sheet 2, are welded to the plate I4 and to the adjacent face of the shell. The arrangement of the ns I9 is best shown in Fig. 2. These ns provide a stagnant varea for shell fluid adjacent the tube sheet yand serve to limit the net free ow area for shell iiuid over the plate I4, preventing flow of shell uid around the bundle of tubes and forcing the flow to be between the tubes. Similar ns may be employed for a similar purpose with the baffles I0 and I3', if desired.

Bailles I3 and I3' provide means, as aforesaid,

for partially cooling the tube sheets. "I'his is accomplished by regulating the flow area of shell uid and consequently the heat transfer rate of cooling shell fluid to the tube sheets so as to cool them more than would be the case if the baffles I3 and I3' were not provided. This is accomplished by forcing the shell fluid to wash over The distance between baille I3 and tube sheet 2, or between b aflle 'I3' and tube sheet 3, will be chosen so as 1 1 to 'provide the desired heat transfer rate between the magnitude of the heat transfer rates Afrom f the Shell uid'and the tube Sheets 2 and 3.

The embodiment of Figs. 1 and 2 illustrates the present invention applied in a. simple type ot heat exchanger. The embodiments of Figs. 3 to 6 and of Figs. 7 and 8 show the invention applied in more complex types of heat exchangerswith additional means provided.

The heat exchanger of the embodiment of Figs. 3 to 6 is indicated generally by the reference numeral 20. It has a hollow base 2I providing a header or chamber 22 and a top flange 23.

. Chamber 22 is insulated with refractory brick or other means 24 and may be connected to a source of heat, as to a fluid-catalyst mixture separator. A tube sheet 25 is mounted on top of the flange 23. The exchanger further has a. composite outer shell l2li, formed of a. flanged bottom shell portion 21 mounted on top of the tube sheet 25, a flanged intermediate shell portion 28 mounted on top of portion 21, and a flanged top shell portion 29 mounted on top of portion 28. Gaskets 30 are provided between the various engaging parts of the base 2 I, tube sheet 25 and shell portions 21, 28 and 29, and these parts are secured together by bolts 3l.'

An inner shell 32 is mounted on tube sheet 25 Y within shell 25. Itprovides, with shell 26, ran annular space 33 therebetween. Shell 32 has a sliding tat its upper end'with an angle bracket 34 secured to a top tube sheet 35, which tube sheet is disposed in shell portion 29 in slightly spaced relation with the inner face thereof. A ring 36 is secured to the top face of the tube sheet 35 by tap bolts 31, a gasket being provided therebetween. A channel or header 38 extends upwardly from and is secured to the ring 36. It may be connected to a chimney, similar to nozzle 6 of Fig. 1. Ring 36 is secured to shell portion 29 by an annular expansion joint flexible collar 39 welded to the ring 36 and to the portion 2 9. Collar 39 has an inside diameter at least as large as lthe inside diameter of the outer shell. Oriflces 40- Iormed in portion 29 afford communication between space 33 and the interior of collar 39 so as l to equalize temperature and pressure therebetween. Shell 32 is shown made as an integral cylinder. However, it may be made of several vertical and/or horizontal sections secured together if desired.

Tubes 4| are disposed in shell 32 with their ends secured in orifices in the tube sheets. The tubes are staggered so that nuid flowing across the shell must flow in a circuitous path between the tubes, no straight-through path in .the direction of ow betweenrows of tubes being provided, `as will presently more fully appeanj Horizontal baffles 42, having orifices for the tubes, and being staggered, divide the shell s2 so that the new therethrough is substantially horizontally across the tubes in a circuitous path downward through the shell. Each baille closes ed the greater portion of 4the cross-sectional area oi" the shell. Tie rods and spacers 43 support the beides.

A danse 44 is secured at its outer edge to the top ilange of shell portionti and at its inner edge to shell 32, thereby dividing space33 into a lower chamber 45 and an upper chamber or space 45'. Shell 32 is strengthened by annular rings 45 tube fluid shall be in counterflow as was the case in exchanger i. Therefore hot tube fluid enters the tubes from chamber 22 and leaves thetubes, passing into channel 38. Thus the tube sheets would be subjected to extremely `high temperatures if they were not protected, as will later more fully appear, The tubes are protected against excessive temperatures in the same manner as-the tubes of exchanger I were protected and no further description thereof' is deemed necessary. Chamber .45 and space 45' below nozzle 41 each holds a relatively stagnant body of shell fluid which to some extent insulates the shell 32 and prevents rapid heat transfer therethrough. The outside of the exchanger 20 may be insulated, if desired, similarly to exchanger I.

Shell fluid of a, lower temperature than the tube fluid enters space 45 through the nozzle 41. Space 45' below nozzle 41 contains a trapped volurne of shell fluid as aforedescribed. Shell fluid directly above nozzle 41 is continually passing into shell 32 through an opening 49. Some shell fluid also passes through the clearances between the tube sheet 35, ring 36 and shell portion 29, and through the orifices 40 into collar 39, providing a substantially stagnant volume of shell uid in the collar 39. The shell fluid passing throughthe shell 32 iiows crosswise of the tubes in a circuitous route as indicated by the arrows. It leaves the shell 32 through an opening 50 communicating with chamber 45.

Special means are provided to protect the tube sheets, as was the case in the exchanger i It will be seen from Fig. 3 and Fig. 4 that a, plate 5|, oriflced for receiving the tubes 4I and spaced a short distance below tube sheet 35, closes ol the upper portion of shell 32 except for a small portion, thereby providing an opening 52. A vertical baffle 53 extends from .the inner face of the shell 32 to substantially the center thereof, and forms i a partition between the plate 5| and tube sheet 35. Opening 49 is .to the rear of the baille 53 (see Fig. 3) and opening 52 is at ythe opposite (front) side of the baille (see Fig 4). Shell fluid passing from space through opening 49 into the space above the plate 5| fills this space-and must iiow crosswise of the tubes over the bottom face of the tube sheet 35,-passing around the free end of baille 53 whereupon it flows back on the other side of the baille 53 to the opening 52 through which it flows into the space above the uppermost baille 42. This flow of relatively cool shell fluid over tube sheet 35 acts to cool the tube sheet 35 more than would be .the 4case were this plate 5| not employed.

` The means for protecting the tube .sheet 25 is somewhat different than the means for protecting the tube sheet 35 and includes, besides the cooling feature, means for supporting the tube sheet 25 to prevent bowing due to weight superimposed thereon, such as the weight of the inner shell, the tubes, the upper tube sheet, the channel 38, and the Ifluid in the inner shell. fully described in a copending application of George B. Farkas, Serial No. 526,683, filed March 16, 1944, and reference may be had thereto. if desired, for a more complete understanding of the structure of the support. Shell 32, below nozzle 48, is partitioned into quarters by vertical walls 54 and 55 disposed at right angles to each other and meeting `atthe center of the shell, wall 55 being made in two pieces 55a and 55D. The portions of wall 54 on opposite sides of the wall 55 are indicated by the numerals 54a and 54h.

A horizontal wall 56 is disposed on top of walls 54 and 55, and a four-piece horizontal wall 51 is disposed between wall 56 and tube sheet 25, each quarter of wall 51 being disposed between adjacent portions of vwalls 54 and 55 and welded thereto. Walls 54 and 55 are each formed of two spaced plates, as is clearly shown in Fig. 6, and the plates of each part of wall 55 are welded to the plates of wall 54.

Walls 56 and 51 have openings 58 and 59 respectively similar to opening 52, opening 58 being on one side of wall 54 and opening 59 being on the other side of wall 54 and vertically aligned with opening 52. Wall 56 also has orifices in line with the spaces between theplates of walls 54 and 55, and stud bolts 60 secure the supporting means to the tube sheet 25, thereby stilening same against bending due to the aforesaid superimposed load. l

The wall 54 prevents the use of tubes 4l in line therewith, and this omission of' tubes 4| would provide a clear way across the shell for flow of shell uid withoutimpingement on any tubes, resulting in a loss of heat exchange eilciency. Therefore dummy tubes 6|, extending through orifices in the ballles 42 and being plugged at both i ends, are employed above wall 54, these` tubes 6| at their upper ends extending through, and being secured in, the top plate 5| and terminating flush with the upper surface thereof.

The supporting means, together with the 4adjacent portion ofthe inner shell and the tube sheet 25, form eight intercommunic'ating compartments, there being four compartments 62 between. the walls 56 and 51, and four compartments 63 Ibetween the wall 51 and tube sheet 25. Shell fluid enters the i'lrst compartment 62 through opening 58, and then ilows counterclockwise in succession through the remaining three compartments 62, openings 64 being provided in the wall part 55a, portion 54a and part 55h between walls 56 and 51 for this purpose. Shell iuid passes from the last compartment 62 to the first compartment 63 through the opening 59, and then flows clockwise in succession through the remaining three compartments 63, openings 65 This support is more f being provided in the wall part 55h, portion 54a and part 55a between wall 51 and tube sheet 25 for this purpose. Shell fluid flows from the last compartment 53 through the opening 5l! therein into the chamber 45 and therefrom to the nozzle 48.

Wall 51 performs the same function as plate. I4 of exchanger I, that is to say, it causes the shell fluid to wash over the tube sheet 25, cooling same. Thus the remarks made in relation to plate I4 applyequally as Well to the wall 51.

It will be apparent from the foregoing description that tube sheets 25 and 35 have been relieved of extreme service stresses, this being partly a result of the cooling action of the shell fluid washing over the tube sheets and partly a result of the freedom for expansion and contraction of the' tubes and tube sheets due to the employment of the flexible collar 39. Therefore the tube sheets can be made thinner than would otherwise be the case, this thinness further assisting in the cooling of the tube sheets and the relieving ofstresses therein. The supporting means provided for the tube sheet 25 makes the use of a thin tube sheet at this location permissible.

In both exchangers I and 20 the shell fluid flows in a circuitous path lengthwise of the shell, and in a-simultaneous circuitous path crosswise of the tubes.

A modified form of supporting means embodying the present invention is shown in Figs. '1 and 8. In the main, it is similar to the supporting means of exchanger 20, and therefore only Y the differences thereover will be described, and like parts will be designated by like reference numerals with al1-accent added. The supporting means of Figs. 7 and 8 is similarto that shown in the aforementioned copending application of George B. Farkas, and reference may be had to this copending application for a more complete description thereof.

Referring to Fig. 7, it will be seen that the portion of the inner shell 32' adjacent the supporting means is made in four flanged parts 66, the flanges 61 being bolted to the plates of walls 54 and 55' `which extend substantially to the outer shell 26. Filler pieces 68' are employed between the plates of walls 54 and 55 adjacent the flanges 61.

Ameans acts as a-bridge from which tube sheet 25 is suspended, the .entire weight superimposed on the tube sheet; 25' being transmitted to the base 2|' vertically in line therewith so that the strongest resistance to this weight is provided.

'I'he feet are reinforced by webs 10. A horizontal wall 1I is provided in the chamber 45" and an opening 12 is formed therein to permit flow of shell fluid to nozzle 48'.

The flows of tube fluid and shell fluid through the exchanger of Figs. '7-8 are similar to the ows through the exchanger of Figs. 3-6 and no further description thereof is deemed necessary. As the walls 54 and 55 are undercut asaforesaid, there will be some short-cutting of shell fluid between the compartments adjacent tube sheet 25 but this undercutting will not be suflicient to materially affect the orderly flow of shell fluid through the compartments adjacent tube sheet 25 in the intended manner.

While there have been hereinbeforedescribed approved embodiments of this invention, it will be understood that many and various changes and modifications in form, arrangement, of parts and details of construction thereof may be made without departing from the spirit of the invention and that all such changes and modifications as fall within the scope of the appended claim are I contemplated as a part of this invention.

The invention claimed and desired. to be secured by Letters Patent is:

A vertical heat exchanger comprising a shell; a horizontal tube sheet closing one end of said shell; tubes in said shell secured in said tube sheet; a header secured to said tube sheet at the side thereof remote from said tubes; and a device for minimizing vthe extent that the temperature in said header affects the temperature of said tube sheet including two vertical walls crossing at right angles to each other in said shell and engaging said tube sheet and shell Wall, providing four compartments, said shell having a port opening to one of said compartments, said device further having a horizontal wall parallel to and adjacent and spaced from said tube sheet and cngaging said vertical walls and shell wall, said horizontal wall having a port opening another of said compartments to said shell, said other compartment being adjacent said one compartment,A one of said vertical walls having a port opening said other compartment to a third compartment adjacent thereto, the other of said vertical walls having a port opening said third compartment to the fourth compartment, and said one of said vertical walls having another port opening said fourth compartment to said one compartment for a. circular series flow between said shell and horizontal wall ports whereby shell fluid washes over the entire adjacent surface of said tube sheet, thereby effecting said temperature minimizing of said tube sheet.

SIGMUND KOPP.

Images