US2181230A - Heat exchange apparatus - Google Patents

Description

Nov. 28, I939. K.-P. GROAT 2,181,230

- HEAT EXCHANGE APPARATUS Filed Nov. 5, 1937 2 sneet s sheet 1 attorneys HEAT EXCHANGE APPARATUS Filed Nov. 5, 19:57 2 Sheets-Sheet 2 AW, ////Q Patented Nov. 28,1939

UNITED STATES I PATENT OFFICE i f nna'r sxcmnca APPARATUS Keith r. Groat, Canton, hio, assignor to York Ice Machinery Corporation, York, Pa, a corporation of Delaware Application November 5, 1937, Serial No. 173,030

7 Claims.

and in certain types of plate one or more ports may be within the marginal Joint and another port or ports may be outside the marginal Joint.

The present invention permits satisfactory seals to be produced irrespective of the location of 'the through port with reference to the marginal joint.

For many years the advantage of forming the plates of thin sheet.metal pressed to produce flow controlling ribs or bosses has been recognized. The present invention is particularly adapted for use with plates of this type, but is capable of use with other types. In recent years, commercial heat exchangers have been constructed, making use of pressed plates formed of non-corrosive alloy steels, and the advantage of such steels, particularly in dairy apparatus, is too well known to require elaboration. For. example, the patent to Seligman, 1,992,097, February 19, 1935, shows a. plate of this general char- 'acter having fiat marginal portions in which the through ports are formed and with which the necessary seals are produced by gasket carrying spacers interposed between successive plates. These spacers, as shown in the Seligman patent, comprise a frame which is grooved on opposite faces to receive rubber gaskets, the gaskets being cemented or vulcanized in place in these grooves. 40 The only disadvantage of this construction is the possibility that if the gaskets do not com- 'pletely fill the grooves, or if the gaskets are not closely cemented or vulcanized in place, small fissures in which bacteria may breed are af- 15 forded. Even if the gasket carrier isinitially perfect, it may, after long use develop fissures between the carrier and gasket.

Another patent to Seligman No. 2,075,236, March 30, 1937, eliminates the gasket carriers as separate elements and provides grooves formed at least in part by pressing the plate, in which grooves the gaskets are cemented or vulcanized. This construction, while simpler than that shown in the earlier Seligman patent, is open to the same possibleobjection. 3

The present invention resembles the structure of the earlier Seligman patent to the extent that a separate carrier element is used, but it difiers from that Seligman patentlin that the carrier is a thin plate and in that the gasket is 5 not mounted in a face groove but, on the contrary, it is U-shaped in cross section and embraces the edge of a suitable opening formed in the carrier plate in such a way that the edges of the slot between the arms of the U-section of lo the gasket are presented to the exterior of the heat exchanger, and consequently even if a fissure between gasket and carrier plate be present, initially or after use, it is wholly external to the 'path of fluid undergoing treatment, and hence 15 harmless.

Another distinction-from the earlier Seligman patent above mentioned is that the marginal portions of the plate, instead of being fiat, are ofiset in such a way as to oiier a shoulder or abutment 20 against which the inner margin of the gasket ring seats. Consequently, when the plates are forced together and the gasket rings, which are customarily made of rubber or the like, are compressed, their lateral expansion is resisted and limited by the shoulder on the plate. Since the shoulder limits inward displacement, and the gasket carrier plate resists outward displacement, undue distortion or spreading of the gasket is prevented. Hence the gasket is no moreseverely 30 deformed than it would be if confined in a groove. Another important fact is that the area of the gasket exposed to fluid pressure is small so that the total force tending to glow the gasket out .is comparatively small. It follows from the facts 35 above set forth that the joint is sanitary and the gasket is adequately sustained against pressure and is forced to perform in such a way that {the formation of internal fissures, even of a temporary character, is minimized if not entirely 4o eliminated.

It may be asked why it is necessary in the structure of the two Seligman patents to cement or vulcanize the gaskets in place. The reason is that the-plates are customarily usedin the ver- 5 V tical position and are not removed from the press for cleaning butv "are cleaned in such vertical position. 4 Some means must be provided for holding the relatively flexible gaskets in place. Further, with thet'emperatures customarily used, 50 the gaskets if made of rubber,- as is the present practice in such heat exchangers, would have a tendency ultimately to lose thein precise form and dimensions unless'theywere adequately sus- The invention will now be described with reference to typical plates used in heat exchangers of this type. Where heating and cooling are carried out in a single exchanger, and particularly where there is regenerative heating and cooling as is common in this art, the plates for a single interchanger .assume various forms. There are commonly end plates, right hand plates, left hand plates, etc., which difier from each other chiefly in the location of the ports or in the presence or absence of certain ports. These facts are well understood. Generally stated, the gasket plates conform to the heat transfer plates with which they are intended to be used.

For present purposes it is deemed sufficient to illustrate typical heat exchange plates and typical gasket plates for use therewith. Except as to cooperation with the gasket, the particular form of plate is immaterial. Consequently, it should be understood clearly that no-eflort is here made to illustrate every possible form of gasket plate which might be used with the various known forms of heat exchange plate. The illustration and description here given are to be considered exemplary and not limiting. Gasket plates embodying the invention can be designed to meet every requirement of this type of exchanger by simply conforming the gasket plate to the heat exchange plate -with which it is intended to be used, according to principles illustrated by the examples chosen for explanation.

In the drawings-- Fig. 1 is a face view of what is called a left hand heat transfer plate. In the present specification the face of the plate will be defined as the raised or embossed side and the recessed or intaglio side will be called the bac The face view of a right hand plate is merely a mirror view of Fig. 1, that is, the parts shown in Fig. 1 on the left will be on the right in the right hand plate, and vice versa.

Fig. 2 is a view of a gasket plate capable of use with all types of left hand plates shown in Fig. 1 and all types of right hand plates of the same design. In Fig. 2 it is shown in position to overlie the left hand plate of Fig. 1. For use with a right hand plate the gasket plate would be turned front to back, so that the upper annular port gasket would be to the right, and the lower an nular port gasket would be to the left instead of in the positions shown in Fig. 2.

Fig. 3 is a perspective view of the left hand plate of Fig. 1, with the gasket plate of Fig. 2 in position. 'Only the lower ends of the two plates are shown and the parts are broken away so as to show the construction and particularly to show how the gaskets on the gasket plate seat against the flange and theshoulder of the heat transfer plate.

Fig. 4 is a face view of what is called an end plate. This plate is ordinarily used as one terminal plate of a series and differs from the .left hand and right hand plates in the fact that the space in its .face does not'communicate with any port.

Fig. 5 is a face view of a gasket plate for use with end plates such as that shown in Fig. 4. Fig. 5 is drawn on a slightly larger scale than Fig. 4.

Fig. 6 is a fragmentary sectional view through the margins of three adjacent plates with two interposed gasket plates. The first and second plates (counting downward) are shown separated so that the gasket is not under compression. The second and third plates are shown positioned as 7 they would be under compression, the purpose of the view being to indicate the position and configuration of the gasket when performing its sealing function.

Fig. 7 is a sectional view drawn on a somewhat larger scale than the other views, showing an end plate, a left hand plate, a right hand plate, a left hand plate and a right hand plate, assembled in the order stated from right to left, between two clamping heads and with the necessary gasket plates. The gasket plates at the opposite ends of the series are of the type shown in Fig. 5. The others are of the type shown in Fig. 2. The line of section is indicated at 1-1 on Fig. 5.

Fig. 8 is a fragmentary view similar to the lower portion of Fig. 6 but showing a possible modification omitting the gasket shoulder on the heat transfer plates.

Figs. Q and 10 show modified gasket plate constructions.

Before attempting a detailed description, it might be helpful to point out that with heat exchangers of the type shown in the Seligman patents, the assembled plates are so formed as to afford intervening spaces. Assuming for convenience in discussion, that the liquid to be treated is milk, the space between the first and second plates would afford a passage for heat transfer.

between the third and fourth for heat transfer medium, and so on in alternation through the series; An elaboration of the idea involving what is called regenerative heating and cooling would involve heat transfer between warm milk and cold milk flowing in alternate intervals between plates. For example, when used in conjunction with a pasteurizer, warm milk entering the exchanger from the pasteurizer might exchange heat with cold milk flowing to the pasteurizerthrough the exchanger.

The flow ducts through which the milk and heat exchange fluid approach and leave the heat exchange spaces are formed by registering the openings in the stack of plates. These must communicate with the proper heatexchange spaces and this result is produced, as it is in the Seligman patents, by causing the gasket which encloses the heat'exchange spaces between any two successive plates, either to embrace or to exclude the flow passage, depending on whether there is or is not to be communication between the heat exchange plate and that particular passage.

Generally stated, there are usually four passages in each plate, 1. e., an entrance passage in each plate for heat exchange liquid and an exit for heat exchange liquid, an entrance passage for milk and an exit passage for milk. Only two of these can communicate with any particular heat exchange space.

However, it should be remembered that according to the treatment desired, the milk may flow through several heat exchange passages in series, or it may flow through said passages in parallel, and the same is true of the heat exchange liquid. Consquently, referring to the left hand plate, Fig. 1 (and the same is true of its sary to elaborate.

ments of circulation. There are four possible arrangements of three ports. There are also four possible arrangements in which there is onlyone port and six possible arrangements -oi. two ports. Thus, for a left hand plate there aresixteen possible port arrangements. Similarly there are sixteen port arrangements for a right hand plate. The same thing is true of the end plate, but. for practical purposes only a few of the possible port arrangements are used. It is not deemed neces- In the practical manufacture of the plates, as proposed in Figs. 1 to 7 inclusive, the manufacturing process is to strike up the boss forming the shoulder around the port and then to cut the ports within the margin of this boss where ports are desired. Whether the boss has a port in it or not, it requires a gasket, and the gasket sealsin exactly the same way whether the boss is ported or not. Since the present invention relates chiefly to the gasket structure and its coordination with the plate, it is unnecessary to elaborate the port arrangement because the location of the gaskets is the same whether the boss is ported or blank. I

All the plates, whether of the heat exchange, the end, or the gasket type, may, if desired, have similar external outlines, and are so shown. The

plates have at their upper ends a perforated ear H and at their lower ends a slotted ear l2, this being chosen as a convenient supporting and alining means. The perforationsin ears receive the plate supporting rod I3 (Fig. '1) and the slotted ears i2 straddle a lower alining rod (not shown) to keep the plates in alinement. This is a known construction. Others may be substltut ed.

' Filler Referring now to the left hand plate 20L, Fig. 1, the plate is pressed from a sheet of stainless steel of uniform thickness. and has aflat marginal portion M which surrounds the entire plate, anda central raised area l formed by embossing the central portion of the plate. The margin of the area i5 takes the form of a shoulder or offset |8.- In the area i5 are pressed flow directing means here shown as cross ribs or corrugations i1 intended to ensure sinuous turbulent flow of liquid across the plate. These cross ribs are illustrative merely as one possible flow directing means. Other forms may be substituted, the invention imposing no limitations in this respect. In the construction shown, each wave or corrugation carries at'its crest two reversely extending dimples I3 and I9, intended to engage reversely ar nged similar dimples on alternating plates and bus sustain the middles of the plates against displacement by fluid pressure differentials.

The plate 22L is illustrated as having four through ports 2|, 22, 23, 24. The ports 2| and 22 are surrounded by independent upwardly embossed rims 25 and 23, while the ports and 24 are surrounded by embossed rims 27, 28, which are not independent but are related to or form continuations of shoulder I. As explained, one or more of the ports 2|24 may be omitted, but regardless oi this the rims 25-28 are present.

Between ports 23 and 24 on the one hand and raised area I! on the other hand are depressions 29, 3|, which serve to connect ports-'23, 2,4 with the interplate space on the face side of the plate. pieces 32, 33 (see Fig. 3) are welded into the grooves on. the back of the plates, such grooves being incidental to the rearward embossing of depressions. The grooves must be filled to which it is subjected tends to give a flat continuous sealing area for that gasket which seals against the back of the plate. Spacing dimples 34, 35 are struck up in the depressions 29, 3|. 3

The ports 2|, 22, 23 and 24 are not cut un possible to form plates 20L with no ports, or

after the plate is embossed. Thus it is easily with 1 port (four combinations) 2 ports (six combinations) 3 ports (four combinations), as well as four ports as shown (total 16 ported left hand plates). While the plate having four ports' is the one commonly used the other arrangements are used in certain cases.

The right hand plates 20R (Fig. 7) are merely right toleft counterparts (mirror reversals) of the plate L, Fig. 1. Right and left plates alter- 1 natc in a stack and the reversal of dimples l8, l9, ensures that the conv sides of the dimples in one plate oppose the cvex sides of the dim- Dles in both of its neigh (see Fig. 7). i

The end plates 4| 0! Fig. 4 are similar except the ports in the plate are differently arranged. There is a fiat marginal portion 44 surrounding the entire plate, 'a'central raised area 45 surrounded by shoulder 46. There are ribs or corrugations 41 with-dimples 48 and 49 reversely arranged with respect to the dimples I8 and IQ of the left hand plate 201'... This last arrangement is chosen arbitrarily and merely entails the result that a left hand plate should adjoin an end plate to secure engagement of the dimples. There are through ports 5|,52, 53, 54, each surrounded by an independent embossed rim 55, 56, 51, 58. As in the case-of the plates 20L, 20R, there may be fewer than four ports, but the embossed rims are present in any case to ccact with the gaskets.

rs, to limit deflection A gasket plate for use in the face of left hand plates- 20L and right hand plates20R (irrespective oi the number of ports in such plates) slotted on their outer peripheries at $4 to receive the margins of the openings in plate 60, which they embrace and to which they are cemented or vulcanized. Consideration of Fig. 6 will indicate that the metal to rubber joint between the gasket and its gasket plate is outside the flow path in all cases and that when the gasket is under pressure the gasket-is closely conflned, is exposed to fluid pressure on only a small area and is sustained in nearly all dircetions. The compression to close rather than open or produce cracks, and consequently,

the diiliculties inherent in gaskets mounted in face grooves are avoided; Another advantage is that, since the gasket even in its compressed-state (see the lower two plates Fig. 6, also the seals visible in Fig. 7) is much thicker than the plate,

any leakage past any gasket will drain outside the machine and no leakage grooves such as have heretofore been cut in the exchange, plates are necessary. There is a drainage space between gaskets SI and 32 and also between GI and 63 (Fig.2), between 68 and "to 14 (Fig. 5) all very clearly shown in Fig. 7.

The end gasket plate 55 (Fig. 5) has a central opening embraced by main gasket 66 and four through ports embraced by gaskets 6'I,'58, 69, 10, each formed and mounted as already described.

A consideration of Figs. 4 and-5 will make it clear that end gasket. plates 65 will seat on the face of end plates 40 and will seal with the back of any plate, particularly left hand plates ML plates as shown in Figs. 2 and 5 can be used with flat marginal or unshouldered plates of the type (for example) shown in Figs. 3 and 4 of Seligman Patent 1,992,097. .This possibility is illustrated in Fig, 8 where 80, 8| represent two successive stacked Seligman plates and 60a represents applicant's gasket plate with gasket Sla. The gasket Bla is not so well confined, as in the preferred construction, and because of the greater area of the gasket exposed to internal fluid pressure, is subject to a greater risk of blowing out if high pressures are used, but the joint between the gasket and itsgasket plate is outside the flow path of material flowing through the heat exchanger so that this desirable feature is present.

While rubber is mentioned as the material for the gaskets and noncorrosive steel as the material and other chemical action, mechanical strength,

and workability are important characteristics. The gasket. plates being outside the flow paths may be made of any suitable material, but noncorrosive steel is contemplated as desirable.

Material for the gasket plates should have the necessary mechanical strength; and surface resistance to corrosion or other chemical action is desirable but not so important as in the case of heat transfer plates. Because of the simple form, workability is less important than in the case of the highly embossed gasket plates. Thus the gasket plate material and the gasket material may be coordinated, in any commercially desirabe way, to offer suitably formed bead gaskets with an external sustaining plate with which the gasket is more or less permanently connected. The important thing is that the gasket shall offer a smooth unbroken surface in the area exposed to flow paths of fluid within the exchanger.

Fig, 9 shows a modified construction of gasket plate in which the plate 6%- is completely enclosed in rubber. The gasket bead Slb is extended as a thin covering which surrounds the plate b as shown, that plate being otherwise substantially as shown in Figs. '2, 3, 5, 6, 7 and 8. Fig. 10 shows another construction of gasket plate which may be used at least where temperatures are not too high. Here the gasket bead Bic and the plate 600 are integrally formed but' have different physical characteristics. Assuming rubber-as the material, bead He is of soft vulcanized rubber and plate 600 is hard vulcanized, i. e., is what is sometimes called hard rubaromather or vulcanite. Such diflferentiations are familiar to persons skilled in the rubber art.

An important distinction from the structure of Seligman No. 1,992,097,'is that the same gasket seals with both plates between which it is interleaved. This applies to the various alternative forms of gasket herein suggested.

While several modifications have been suggested, others are possible within the scope, of i this invention and the specific disclosures herein made are intended to be illustrative and not limiting.

What is claimed is:

1. In heat exchange apparatus of the separable plate type, the combination of a series of heat exchange plates arranged in spaced stacked relationto form interplate flow channels, at least some of said plates having through ports, some of which ports are adapted to communicate with said interplate channels; gasket plates interleaved between the heat exchange plates and having an opening conforming to said interplate channels and said communicating ports, and at least one port adapted to register with another port in the heat exchange plates; gaskets carried by said gasket plates and surrounding said opening and ports, each such gasket sealing with the twoheat exchange plates between which the gasket plate is interleaved and the plates being formed with shoulders coforming to the internal contour of the gaske ,and serving to limit inward displacement of the gaskets, under sealing pressure, whereby flow of the gaskets and the gasket area exposed to fluid pressure are minimized; and clamping means between which said plates are confined under seal producing pressure. 7

2. A gasket plate for heat exchange apparatus of the plate type, comprising a plate having at least one opening therein; and a resilient gasket embracing and enclosing the wall of said opening and permanently secured thereto to present an unbroken surface within said opening and sealing surfaces at opposite faces of the plate, said opp sed sealing surfaces being of small transverse dimension as compared with adjacent portions of the plate, which plate extends from an the plate extending beyond the gasket suihciently to serve as a rigid beam resisting outward displacement of the gasket.

4. A sealing gasket plate for plate type heat exchangers, comprising a metal plate having at least one fluid flow opening therein; and a. continuous gasket channeled in cross section, and secured to the edge of said opening in such manner that the'joint between the-gasket and the metal'is remote from said flow opening and an unbroken gasket surface is presented thereto, the plate extending from the bottom-of the channel in the gasket a substantial distance beyond the gasket, whereby a gasket of moderate sealing area is adequately sustained against outward displacement by the plate.

5. A sealing gasket plate for interposition between the heat exchange plates of plate type heat exchangers, and comprising a metal plate having a polygonal fluid flow opening therein; and a channeled sealing gasket adapted to seal with the plates between which it is interposed, said gasket surrounding said opening with the marginal portion of said opening in said channel and the joint between said channel and the edge of the plate around the opening facing away from the consequently isolated from contact with fluid flowing through the said opening by the seals formed between the gasket and the adjacent heat exchange plates, a portion of the plate thinner than the gasket even when compressed, extending outward beyond the gasket and serving to sustain the gasket and resist its distortion while affording a 4 drainage path for leakage.

6. In a heat exchanger of the separable plate type, the combination of a series of heat exchange plates arranged in spaced stacked relation to form interplate flow channels, at least some of said plates having through ports some of which ports are adapted to communicate with said interplate channels, said plates being oflset to form continuous shoulders one of which surrounds an interplate flow channel and another of which surrounds a port in the plate; apertured gasket plates interleaved between successive exchange plates, the apertures in said gasket plates conforming to but being larger than the areas embraced by the shoulders on the heat exchangeplates whereby the gasket plates are received between the ofiset portions of the heat exchange plates; continuous gaskets mounted on and enveloping the margins of the apertures in each of said gasket plates and sealing .with ofiset portions of the two adjacent heat exchange plates and with the shoulder on one of said plates, the gasket plates having suiiicient width outside the gaskets to sustain the gaskets against outward displacement and the shoulders on the heat exchange plates serving to sustain the gaskets against inward displacement and to limit the area of the gaskets subjected to fluid pressure; and clamping means between which said plates are confined under seal producing pressure.

7. A gasket plate for heat exchangers of the separable plate type comprising a substantially rigid plate having an opening therethrough, and a resilient gasket on the margin of said opening and permanently attached to said plate, said gasket presenting a continuous unbroken surface within the opening and sealing areas projecting above both faces of said plate and each surrounding said opening, and the plate having a portion external to the gasket and adapted to serveas a stifiening member which sustainsthe gasket against outward displacement.

KEITH P. GROAT.

} CERTIFICATE OF CORRECTION; Patent No- 2,181,2 0. r November 28, 19 9.

-ICEITH P. snow.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page.5, first column; line 12, claim 5, for the words "from the read from and; and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 26th day of December, A; D. 1959.-

I Henry Vai1 Arsdale, (Seal) 4 Acting Connniasioner of Patents.

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