US3404733A

US3404733A - Plate-type heat exchanger

Info

Publication number: US3404733A
Application number: US655980A
Authority: US
Inventors: Jr John E Pottharst
Original assignee: Individual
Current assignee: Individual
Priority date: 1967-06-21
Filing date: 1967-06-21
Publication date: 1968-10-08
Anticipated expiration: 1985-10-08

Description

OCta 8,

J. E. POTTHARST, JR

PLATE-TYPE HEAT EXCHANGER 3 Sheets-Sheet 1 Filed June 21, 1967 D/J 7. //V

.. c/Ofifi Z, Pod 40AM, J).

INVENTOR.

ATTORNEY 1968 J. E POTTHARST, JR 3,404,733v

I PLATE-TYPE HEAT EXCHANGER Filed June 21, 1967 I 5 Sheets-Sheet 5 .106 Po fzbarsf, J.

INVENTOR.

A Z'Z'ORME YJ.

ABSTRACT F THE DISCLOSURE A heat exchanger including a plurality of identical, generally rectangular, flat flow plates. Each plate has a lip extending around its perimeter and a gasket secured to"the lippcdside of each plate To secure the gaskets, the platemay have a 'pluralityof'spaced integral gasket keys and the gaskets have mating apertures. The gaskets haveflo w apertures which mate with the flow apertures in the plate and barriers surrounding each flow aperture. Slits' are provided in a-mating pair of barriers to permit fiewnemone end to the-"other. The gasket is provided with fingers which=form a tortuous path from one end of the plate to-the other end.

. Background of the invention 'Thi's",applicationi is 'a 'eontinuation-in-part of my copending applie'ation S.N. 612,220, filed Jan. 27, 1967, now abandoned and entitled Plate -Type Heat Exchanger.- This invention relates to a plate-type heat exchanger. V v,

uid processes ,it is necessary to either "I u us heat orjcool oneof the fluid streams. Various types of heat'exchangersi are used for. this. Operation. One type thatis often u'sled'isthe. plate typeh'eat exchanger which is forrned of aj rnl'lltiplicity efiplates clamped together ine'spacedfside-byeside relationfThe' space between the plates provides aiflowepath on each side of the plates. As a rule, a'pairL-of assa es ,1 is provided for each flow stream; The ipa sagesjare arranged 'so that, alternately, one flow stream passes. throughthe passages in the, plate and. the other stream flows between, the plates. Accordingly, one stream' flowsj along the opposite side of the same plate, in,,'heat exc'hangefrelatjion. In order to obtain af' good heat exchange relation, the flow streams usually follow a' 'tortulous pathi an'd fiow'contra to each other.

,In certain processes the -heat exchange requirements are quite strenuous.For example, inthe continuousdistillation of sea water thelsea water feed stream which may beat a rate. of 3 m4 gallons per minute is raised fromlambient temperature to approximately 200.F. In such'distilla'tion units efliciency'is of paramount importance and, it is very des'i'rable that all heat be properly utilized." In, such" processes there may be two heated, discharge streams audit is preferable, that both be utilized to raise the temperature of theflcold sea water feed stream. One of the heated streams is distillate which is potable water' and-the other is heated-sea water. Naturally, the two heatedstreams' cannot be combined and it is essent'ial. that they. be kept separate throughout their travel through the; heat exchanger. Moreover, in view of the corrosion:characteristicsof the teed stream, whichis sea water,}and onef ofltheLheaIedTstreams, which is heated seawater, it is' ,"ess'ential"tha tspecial precaution be taken to avoid. 'corr0sion. Ac ;IQ Cd iiigly, essential that the heat exchanger be so designed that there is no possibility ermineg thejs'trea s and that :Erevices and other features whic' i, 'c'ould increase-thelikelihood of corrosion be avoidedf ln view of the large amount of fiow involved, it ises'sential' that precal'itions' be taken to prevent the blow outfot the gasketswhich'aresandwiched between United States Patent 0 3,404,733 Ratented Oct. 8, 1968 1 to cement the gasket to one side of the plates. The cementing is in many respects a time consuming task and r if 'notcarefully'executed can result in gasket blowout or crevice corrosion. While there are many. commercialtype plate heat exchangers available, there are no known Satisfactory commercial plate-type heat exchangers for corrosive service utilizing compound streams.

' The present invention is designed to provide a'platetype heat exchanger which utilizes compound heated streams to heat a cool feed stream, and which is so designed that gasket blowout is prevented and corrosion minimized. Moreover, the present invention provides a plate-type heat exchanger in which the cementing of gaskets between plates is eliminated.

Summary of the invention The plate type heat exchanger of the present invention is formed of a plurality of identical, generally rectangular, flow plates having a generally flat surface except for a lip extending around the perimeter of a plurality of gasket keys. Each plate is provided with spaced apertures located adjacent each longitudinal end. The apertures form pairs to provide flow paths for different flow streams. A gasket having apertures mating with the apertures in the flow plates is secured to the lipped side of each plate. The gasket has apertures whichmate with the gasket keys in. the plate. The lip provides lateral support for the gasket, thereby preventing blowout. The gasket keys lock the fingers of the gasket in place and eliminate the necessity of gluing. The gasket material forms a barrier about each aperture and provides a tortuous path from one end to the other. The tortuous path provides a longlength flow. path, thereby obtaining desired fiow velocity. Slits are provided in the pair of barriers controlling one of the flow streams whereby one stream can fiow from an opening on one end through the tortuous path to-the opening atthe other end. The other streams flow directly through the aperture in such plate and gasket. The plates are clamped together in side-by-side relation with the gasket providing spacing for a flow path between plates, and gasketed passages for unopened flow streams. The plates are so arranged that one of the flow streams flows in one direction between; the other fiow stream which flows in" the opposite direction. With the above construction it is possible to arrange the heat exchanger so that one stream will be in excellent heat exchange relation with one or more streams of a dilferent temperature. The construction is such that the heat exchanger may be a single pass arrangement or a multiple pass arrangement. With a multiple pass arrangement flow direction plates are used to change the direction of flow.

- While. the preferred embodiment illustrates a heat exchanger in which there are three separate flow streams, the invention is not so limited. The lip and gasket keys may be utilized in gasketed plate heat exchangers in which there are only two flow streams.

Brief description of the drawings 7 FIG. 1 is an isometricdiagrammatic view of a twopass plate-type heat exchanger constructed in accordance with the present invention; FIG. 2 is an end elevation view illustrating the clamping together of the heat exchanger shown diagrammatically in FIG. 1; FIG. 3 is a sectional view taken on lines 3-3 of FIG. 1; FIG. 4 through FIG. 8 are plan views of gasketed plates utilized in the construction of the heat exchanger shown in FIG. 1 with FIG. 4 being the master gasket which is utilized in all of the plates;

FIG. 5 illustrates how the'master gasket is cut for one of the flow streams; I

FIG. 6 illustrateshow the master gasket is cut for the flow direction plates; i

FIG. 7 illustrates how the master gasket is cut for the second of the flow streams; I v

FIG. 8 illustrates how the master gasket is cut for the third of the flow streams; 7

FIGS. 5A, 7A and 8A are details of FIGS. 5, 7 and 8 to more clearly illustrate the slitting of the barrier of the gasket;

FIG. 9 is a sectional view taken along lines 9-9 of FIG. 4;

FIG. 10 is a plan view of a flow plate showing the location of gasket keys;

FIG. 11 is a sectional view taken along lines 1010 of FIG. 10 showing the gasket key; and

FIG. 12 is an enlarged plan view of a portion of the plate illustrated in FIG. 10 illustrating the positioning of gasket keys around the apertures.

Description of the preferred embodiment Referring now to the drawings, it can be seen that the plate-type heat exchanger of the present invention is formed from a multiplicity of plates 10 which are disposed together in side-by-side relation. Interposed between the plates 10 are gaskets 12 which separate the plates 10 and provide space for a flow path between adjacent plates 10, as will be explained subsequently. The heat exchanger is so designed that all of the flow plates 10 are identical in construction and the gaskets 12 which are secured to one side of the fiow plates 10 are formed from a common master gasket. Such design lends itself to economical manufacture and repair.

The preferred embodiment chosen to illustrate the invention is a two-pass exchanger and a flow direction plate 16 is disposed at the midsection to change the direction of flow. However, the same type of construction may be utilized to form a single-pass heat exchanger or a more multiple pass heat exchanger, in which case a flow direction plate 16 would be located at each level where it is desired to change the direction of flow.

Referring now to the plates10 which are shown in more detail in FIGS. 4 through 8, it can be seen that the flow plates 10 are generally rectangular and are fiat except for a downtumed lip 18 which surrounds the perimeter of the plate 10, see FIG. 9. If the heat exchanger is to be used in corrosive service such as in a sea water distillation process, the plates 10 may be formed from a noncorrosive material such as 90/ 10 copper-nickel or other similar material. All of the flow plates 10 are provided with three spaced

passages

20, 22, 24 adjacent each longitudinal end. An aperture at one end is paired with an aperture at the other end for each flow stream.

A master gasket 12 having

apertures

28, 30, 32 which mate with the

passages

20, 22, 24 of the flow plate 10 is secured to the, lip side of each flow plate 10. The lip 18 provides lateral support for the gasket 12 preventing gasket blowout due to the pressure of the flow through the heat exchanger. The master gasket 12 has

barriers

34, 36, 38 about each

aperture

28, 30, 32. Between the barriers on the two ends the gasket has a'plurality of fingers which form a tortuous path 40 ,from one end of the gasket 12 to the other. The tortuous path 40 provides a long-length flow passage thereby providing the desired flow velocity. The heat exchanger is so designed that a plate 10 having a master gasket 12 secured thereto is used throughout. Therefore, if perchance one of the plates becomes damaged it is only necessary to obtain a master plate and gasket 'to repair the' heat exchanger.

As can be seen from an examination of FIGS. 5 through 7, the gasketed plates are provided with slits 42 in a pair of barriers to permit the fiow stream from one of the apertures to flow along the surface of the plate through the tortuous path 40.- For example, in FIG. 5 there are slits 42 inbarriers 36-36 which surround apertures 3 0 30. Therefore, the stream flowing through passage 22 in the plate can. flow front passage 22 on one end of the plate 10 through the tortuous path 40 to the passage 22 at the other end ofthe plate 10. The plates 10 controlling the-otherfiow streams are similarly provided with slits, 42. which likewise open flow, for one ofthestreams sosthatsuch stream .can flow through the tortuous path 40'al0ng the surface of the plate 10. While the gasket 12 may be cemented or vulcanized to the lipped side. of each, flow plate 10, cementing is a tedious process and to prevent crevice corrosion care must be taken to see-that there is no, cement extending past the edges of the gasket material. If cementing is not carried out properly, a finger may become dislodged blocking flow throughthe gasketed area. Accordingly, it has been found that for many installations it is preferable to provide the flow plates with a plurality of integral gasket keys13 which are formed in the plate10 by stamping, see FIGS. 10-12. In such case, the gasket 12 is .provided with apertures 15 which cooperate with the gasket keys 13 to lock the gasket in position. With such construction it is not necessary tocement or vulcanize the gasket 12 to the flow plates-10. It has been found that, whereas cemented gaskets may blow out at 35-40 p.s.i. gaskets secured by gasket keys 13 and lip 18 will withstand p.s.i. The keys 13 and apertures 15 are so positioned on the plate and gasket that each finger is provided with proper lateral support. Keys and apertures are also provided about the barrier surrounding thev flow apertures, see FIG. 11.

In order to have'a two-pass heat exchanger, flow direction plate 16 is interposed in the midsection of the heat exchanger. The flow direction plate 16 has

openings

44, 46, 48 only at one end with the other end remaining solid. The solid end of the flow direction plate 16 arrests flow through the gasketed passages and causes the flow stream to flow through the flow paths between the plates 10 from one side of the heat exchanger to the other. A master gasket 12 is secured to the fiow direction plate 16. To utilize the heat transfer surface of the flow direction plate 16, one pair of barriers are provided with slits 42. If more passes are'desired, the heat exchanger may 'be provided with additional flow direction plates.

As can be seen from FIG. 1, the plates 10 are positioned together in side-by-side relation with a gasketed plate controlling the first flow stream alternating with gasketed plates controlling the other two flow streams. For example, in FIG. 1 it can be seen that the feed stream which may be a cold sea water feed stream to be heated by the two heated discharge streams is positioned between the blow-down stream and the distillate stream. The gasketed plates controlling the feed stream are labelled F and gasketed plates controlling the discharge streams are labelled B and D. Therefore, thefeed stream is in heat exchange relation with the two heated streams in counterflow relation. It has been found possible to raise the temperature of a cold sea water feed stream from ambient temperature to approximately 200 F. at the rate of 3 to 4 gallons per minute in a two-pass heat exchanger con- 'structed in accordance with the present invention.

In addition to the flow plates 10, gaskets 12 and flow direction plate 16, the completed heat exchanger has two

covers

50 and 52. Cover 50 is positioned on the top of the stacked assembly of plates 10 which is shown in FIG. 1 and cover 52 on the bottom of the assembly, vsee FIG. 2. The

covers

50 and 52 and the plates 10 have a plurality of alignment holes 54 and alignment rods 56 are run through the alignment holes 54. The rods 56 have threaded portions 58 on each endand nuts 60 are threaded thereon to compress the stacked plates 10. In order to assure proper alignment, it may be desirable to. havea close fit between the rods 56 and the alignment. holes 54. Care should be taken to see that all the plates 10-are brought down evenly so that there is no bending ordeformation of any of the plates 10 in order thatthere' can bean even compression throughout to prevent any po'ssible le'akage. The gaskets I Z-are, ;secu-red to the botton 'side of each plate,10. The gaskets are also in contact..wi th the-'top surface of the m te-1m ndernea t e asket-.- -s s assembly should be compressed sufficiently so that there is no leakage in the assembly.- r

Welded to the top plate 2 and bottom plate ,64 are the inlet nozzles '66 and outletjno'z zle's 68. The top and bottom plates 62 and 64 are'similar to the remaining flow plates except that there 'a'rer'1o'apertures, on one end of these plates as can be seen in FIG l. There is one ,pair of nozzles for each'fl'ow stream. The nozzles 66-68 extend through openings inthe covers 50-52. As can be seen, on the top there are the inlets 66 for the two heated streams and the outlet 68 for cold feed stream. On the bottom side there are the outlets 68 for the two heated streams and the inlet 66 for the cold feed stream. As can be seen, all of the outlets and inlets are located on the same side of the heat exchanger. Also, as mentioned previously, there are no passages in one end of the flow direction plate 16 and the blank end is in line with the inlet and outlet nozzles 66-68. Since the gaskets 12 are attached to the bottom side of each plate 10, is is not necessary to have a gasket attached to the bottom plate 64 as it is merely used as a closure for the first flow space. The top plate 62 is provided with its regular gasket.

Accordingly, the two heated streams flow into the heat exchanger through inlet nozzles 66 and then flow downwardly through their respective passages in the plates 10 until they contact the blank wall of the flow direction plate 16. The streams then flow out through the slits 42 in their respective barriers and flow along hte tortuous path 40 between the plates to the other side of the heat exchanger, see FIG. 1. At the other side, the flow streams reform and flow through respective passages in the plates 10, through the flow direction plate until they strike the bottom cover where flow is again arrested and the two streams again spread out, flowing back through the tortuous path 40 to the other side of the heat exchanger, where they reform and flow through their respective passages in the plates 10 and thence out the outlets 68. In the meantime, the feed stream comes in from the opposite direction and follows the same course of action, flowing down through the passage formed# by the openings until flow is arrested by the wall of the flow direction plate 16, at which time it spreads out through the slits 42 in the barriers and flows between the plates 10. As can be seen, the heat exchanger is so arranged that the feed stream flow's between the two heated streams. Also, as can be seen, the path of the streams is a tortuous path provided by the gasket and, therefore, there is good contact for a good heat exchange relation between the streams.

While the preferred embodiment of the heat exchanger has been shown arranged as a two-pass exchanger, the principle of the invention may also be used in a one-pass heat exchanger or a more multiple pass heat exchanger, and arrangements of plates other than that shown may be used. While the construction is such that a stream of one temperature may be placed in heat exchange relation with two separate and different flow streams of another temperature, the principle of the invention may be utilized in heat exchangers having only two flow streams.

From the foregoing it will be seen that this invention is one well adapted to attain all of the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the apparatus.

It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be. understood that .allmatter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative andnot in a limiting sense.

1. A plate=typeheat exchanger comprising a plurality of identical plates and'initially identical gaskets, [each plate being substantially flat except fora lip extending around the perimeter and having at least .two' spaced apertures adjacent each longitudinal end, an "aperture at oneen'd being paired with'an" aperture at the other end, a gasket secured to the lipped side of the plate with the lip providing edge 'support'for the gasket, each gasket having apertures mating'with the 'apertures in the plates and having a barrier about each gasket aperture, the barrier about a mating pair of gasket apertures being at least partially removed to provide a path from one of said gasket apertures at one end of the plate to its paired aperture at the other end of the plate, the plates being clamped together in side-by-side relation with the gaskets providing a space between adjacent plates whereby fluid from a mating pair of apertures may flow between adjacent plates, remaining apertures in the plates and the gaskets providing a gasketed passage for the unopened flow stream, and inlet and outlet nozzles for each flow stream.

2. The heat exchanger specified in claim 1 wherein the flow plates are provided with a plurality of integral gasket keys and the gaskets are provided with key apertures cooperating with the gasket keys to secure the gasket to the plate.

3. The heat exchanger specified in claim 2 wherein fingers extend from opposite longitudinal edges of the gasket on an alternate basis to form a tortuous path for the flow stream from one end of the plate to the other whereby the flow on one side of a plate is in counteropposition to the flow on the other side.

4. The heat exchanger specified in claim 3 include a flow direction plate having apertures at only one end to change the direction of flow and thereby repass the fluids past each other again in heat exchange relation.

5. The heat exchanger specified in claim 3 wherein there are three flow streams, one of a first temperature and two different flow streams of other temperatures and the plates are so arranged that one flow stream is sandwiched between the other two flow streams.

6. In a plate-type heat exchanger in which a feed stream of a first temperature is passed in heat exchange relation with a.- stream of a second temperature comprising a plurality of identical flow plates, each of said plates being substantially flat except for a plurality of integral gasket keys spaced about the surface of the plate, said plates having at least two sets of apertures, said sets of apertures being spaced from each other and one aperture from one set being paired with an aperture from the other set; a gasket secured to the keyed side of each plate, each gasket being initially identical and having apertures which mate with the apertures in the plate and a barrier which surrounds each gasket aperture, the gasket also having a plurality of fingers to form a tortuous flow past from one set of apertures to the other and a plurality of key apertures which cooperate with the gasket keys to secure the gasket to the plate, the gasketed plates being clamped together in side-bysicle relation, at least a portion of a pair of the barriers in each gasket being removed thereby opening the gasketed passage formed by the mating apertures in the plates and the gaskets so that such stream can flow through the tortuous gasketed path between the plates from an aperture at one end to its mating aperture at the other end.

7. The heat exchanger specified in claim 6 wherein the plates are provided with peripheral lips to provide additional lateral support for securing the gasket.

8. The heat exchanger specified in claim 6 wherein there are three flow streams, one of a first temperature and two different flow streams of another temperature and the plates are so arranged that the first flow stream is sandwiched between the other two flow streams.

9. The heat exchanger specified in claim 6, wherein the fingers forming the tortuous flow path extend inward from opposite sides of the gaskets on an alternate basis so that the flow on one side of a plate is countercurrent to the flow on the other side of the plate.

10. The heat exchanger specified in claim 6, wherein slits are made in the barrier to form the flow path and the portion of the barrier remaining has key apertures to cooper-ate with the gasket keys to secure said portion of the gasket to the plate.

References Cited 1,890,108 12/1932 Chatain 165%166XR 2,248,933 7/1941 AStle "165 -167 2,777,674 1/1957 Wakeman 165-5161 FOREIGN PATENTS 57,1 69 1/1940 Denmark.

995,395 8/1951 France.

835,007 3/1952 Germany.

ROBERT A. OLEARY, Primary Examiner.

M. A. ANTONAKAS, Assistant Examiner.