HEAT TRANSFER PLATE

Abstract: A heat transfer plate for heat transfer apparatus, such as heat exchangers or evaporators is disclosed which is at least partially bounded by a groove (32) for receiving a gasket for general conformity therewith and to seal against an adjacent plate, wherein; the groove comprises an inner side wall and an outer side wall; the outer side wall of the groove is provided with a number of lateral bays (30), the gasket being formed with a number of corresponding spaced projections engaging in and matching with said bays; the base (33) of each bay is at a level other than the base (34) of the groove, and; each bay (30) does not communicate with the ambient thereby limiting movement of the gasket material along each said bay. The embodiments of the invention have a common feature that the gasket sealingly engages the rear wall (27). This en­ gagement limits extrusion of the gasket material along the bay of the groove and thereby prevents «blowing-out» of the gas­ ket at these points. Furthermore the floor of the bay, (40) is at a level other than the floor of the groove (42). This difference in level aids engagement between the gasket and the heat-­ transfer plate.

Description: Title:IMPROVED HEAT TRANSFER APPARATUS This invention relates to plates for heat transfer apparatus. such as heat exchangers or evaporators. In such heat transfer apparatus heat is transferred between two thin. broad streams, which may be both of liquid or one stream of liquid and one stream of vapour or two streams of vapour, or in some cases one or both streams may have mixed liquid and vapour phases. The streams are separated by plates assembled in a spaced face to face relationship to provide flow spaces between the adjacent faces of the plate. The boundaries of the flow spaces are enclosed and sealed by flexible or resilient gaskets surrounding the flow spaces between the flow spaces and entry and exit ports. The ports. in plate heat exchangers usually one at each corner of the plate. are similarly surrounded or part-surrounded by gaskets. A substantially similar construction to that used in plate heat exchangers has also been employed in tissue-culture vessels, which makes advantageous use of the large surface area afforded by such a construction. In such vessels the gasketing contains a possibly pathogenic organism and in some embodiments is subjected to the thermal shock associated with steam cleaning. it is therefore of the utmost importance that the gaskets sealing ability is not compromised. Each gasket is normally of a one piece construction set within a pressed groove formed in the plate. The manufacture of the gasket is normally carried out in moulds, but according to the size of the plate or the manufacturing techniques used the gasket may be assembled from two or more smaller components. The gaskets are normally moulded of an elastomeric material. The sealing force against the fluid pressure in the flow space is obtained by compression of the gaskets in a direction normal to the plate surface and the resistance to gasket extrusion from the proper sealing position in the groove is normally enhanced by securing the gasket to the plate surface by the application of a system of adhesion, which is necessary in certain applications in order to minimise gasket movement which would result in leakage. Such movements can arise because changes in the loading condition of one gasket will alter the condition of the gasket on either side, and, perhaps of greater importance, the gaskets are assembled into the groove which is formed from this sheet material and which is therefore flexible. This system of adhesion is frequently complex and time consuming, involving the application of an adhesive to both the gasket and the plate surface, and assembly of the two components together. According to the system which is adopted it may be necessary to prepare the mating surface of either component before assembly and it may be necessary to subject the assembled components to a process designed for curing the bond after assembly. The foregoing description covers the initial manufacturing process. It is common practice that as the elastomeric gasket material hardens and deforms in use with the passage of time. the servicing of the plate head exchanger at the user's factory requires the replacement of the gasket. Removal of the old gasket requires destruction of the adhesive bond and cleaning of the groove. Also. it is not always possible to subject the newly assembled gasket to the optimum process of adhesion such as would be applied during initial manufacture by the supplier. It is an object of the invention to provide mechanical engagement of the gasket with the plate so as to avoid the necessity for a system of adhesion. It is well understood in industrial practice to form a seal groove in the face of one component. which groove has an opening smaller in dimension than the resilient gasket which has to be inserted through the opening. The gasket is thus releasably secured by its own resilience. Such a groove is difficult to form in a pressed plate in that it would not be readily produced in a one-hit pressing operation. It is a known practice in the manufacture of plate heat exchangers to attach a resilient gasket to an aperture in a substrate material by pushing somewhat oversize projections through apertures located in the floor of the groove. It has also been suggested, that the gasket should be secured to a surface by fixing means such as a mask. or such as tabs which are attached to or integral with the gasket and are secured to the surface outside of the sealing area. The latter method is illustrated in the German Patent No. 832 975. A further known gasket, as best illustrated in the U.S. Patent No. 4377204 teaches that the tab should lie in a trough, and be attached by the known oversize projection method related above. According to a first aspect of the present invention there is provided a heat transfer plate at least partially bounded by a groove for receiving a gasket for general conformity therewith and to seal against an adjacent plate, wherein; a) said groove comprises an inner side wall and an outer side wall, b) the outer side wall of the groove is provided with a number of lateral bays. the gasket being formed with a number of corresponding spaced projections engaging in and matching with said bays. c) the base of each bay is at a level other than the base of the outer side wall of the groove. and, d) each bay does not communicate with the ambient thereby limiting movement of the gasket material along each said bay. According to a second aspect of the invention, there is provided a gasket for use with a heat transfer plate at least partially bounded by a groove, the gasket being formed of a compressible material and having a number of spaced projections to correspond with a number of bays provided in an outer side wall of the gasket groove. the spaced projections engaging in and matching with the said bays on installation of the gasket in the groove. wherein each said projection is less thick in a direction normal to the plane of the said plate than the body of the gasket Conveniently, at least one of the said bays is provided with means for securing the corresponding matching projection of the gasket thereto. In an embodiment. the means for securing the corresponding matching projection of the gasket comprise an aperture in the plate which co-operates with a stud provided on the gasket. In a further embodimnt the gasket is provided with a peaked upper surface to engage and seal on an adjacent plate. The invention also extends to combinations of the gaskets and heat transfer plates as disclosed herein. The invention will be further described with reference to the accompanying drawings in which: Figure 1 is a plan view of a known heat transfer plate; Figure 2 is a section on the line X-X of Figure 1; Figure 3 is an elevational view of one form of gasket groove according to the present invention, Figure 4 is an enlarged section on the line Y-Y of Figure 3. with the gasket added; Figure 5 is an elevation of another form of gasket according to the present invention; Figure 6 is an enlarged section on the line Z-Z of Figure 5, and Figure 7 is a view similar to Figure 4 showing a further modification. Figure 1 shows an outline of a conventional heat exchanger plate in which the plate 1 has the usual and exit ports 2 and the central heat transfer area 3 surrounded by a resilient gasket 4. As shown in Figure 2, which is a section XX through the gasket (shown dashed). the gasket 4 is mounted in a pressed groove 5 and attached to the plate by means of an oversize projection 6. which protrudes through a hole 11, at a fixing point located in a trough 7. One problem with this arrangement is that the considerable overpressures which occur in the flow spaces of a heat exchanger extrude the gasket 4 along the trough 7. and cause the sealing to fail at these fixing points. In another well known form of plate design the gasket groove 19, as shown in Figure 3, is provided with lateral enlargements in the vertical wall 20 as shown at 11. By this means the width of the gasket groove is locally enlarged. It is proposed that between some or all of these enlargements the groove edge 20 should be formed as indication by the numeral 21 and as shown in Figure 4, to provide lateral bays 21 in the gasket groove. In a preferred form of the invention the lateral bays 21 are provided with apertures 25 and protuberances 10 are provided on the gasket, being manufactured to such dimensions that the protruberances will be slightly compressed when entering the apertures so that the gasket 8 and plate 3 will remain assembled, but can be dis-assembled by pulling the gasket away from the plate. It should be noticed that the wider portions of the gasket groove are normally positioned to alternate one with another from plate to plate, and thus in this embodiment the protuberances 10 remain unaffected by compression when the plate pack is tightened to operable conditions, because the apertures 25 and protruberances 10 are well removed to one side of the sealing surface of the gaskets. It should be understood that the apertures 25 are not restricted in their placement to the base of the bay 21 but may be located in the rear wall 27 of the said bay or where the bay has side walls. they may be located in such side walls. In an alternative form of the invention shown in figures 5 and 6, the bay 30 is not located between two enlargements, but provided in the flat outer wall 31 of a gasket groove 32. having a floor 34. An aperture 33 is provided in the base of the bay thereby enabling the gasket to be secured to the heat transfer plate. Furthermore, in this embodiment the bay 30 is rectilinear rather than curvilinear as in the embodiment of figure 3. In figure 7 an embodiment is illustrated in which the base 40 of the bay 41 is below the base of the groove 42, and the gasket 43 is so profiled as to enable the plates to be sealingly mated against one another. The embodiments of the invention illustrated in the accompanying drawings and described herein have a common feature that the gasket sealingly engages the rear wall generally indicated by the numeral 27. This engagement limits extrusion of the gasket material along the bay of the groove and thereby prevents "blowing-out" of the gasket at these points. Furthermore the floor of the bay. (for example indicated as 40 in figure 7 and as 33 in figure 5) is always at a level other than the floor of the groove (indicated by 42 in figure 7 and 34 in figure 6). This difference in level aids engagement between the gasket and the heat-transfer plate. Various modifications may be made within the scope of the invention. for example, the gasket may be formed with recesses in the exposed face adapted to seal against the adjacent plate to receive the ends of the projections from the gasket in the groove in that adjacent plate.

Claims: CLAIMS 1. A heat transfer plate at least partially bounded by a groove (19,32) for receiving a gasket (8,43) for general conformity therewith and to seal against an adjacent plate, wherein said groove (5) comprises an inner side wall and an outer side wall (20,31), the outer side wall (20,31) of the groove (19,32) is provided with a number of lateral bays (21,30), the gasket (8,43) being formed with a number of corresponding spaced projections engaging in and matching with said bays (21,30), the said projections including means for securing the gasket (8,43) to the plate at the location of the said bays, characterised in that the base (33,40) of each said lateral bay (21,30) is at a level other than that of the base (42) of the outer side wall of the groove, and in that each bay does not communicate with the ambient thereby limiting movement of the gasket material along the bay. 2. A plate according to claim 1, characterised in that the means for securing the projection to the plate comprises an aperture in the plate in the region of the lateral bay and a matching stud or protuberance on the projection. 3. A gasket for use with a heat transfer plate at least partially bounded by a groove (19,32), the gasket being formed of a compressible material and having a number of spaced projections to correspond with a number of lateral bays provided in an outer side wall of the gasket groove, the spaced projections engaging in and matching with the said bays on installation of the gasket in the groove, characterised in that the projections are adapted to be secured in the said lateral bays to retain the gasket on the plate on installation of the gasket in the groove, and in that each said projection is less thick in a direction normal to the plate than the body of the gasket. 4. A gasket according to claim 3, characterised in that the gasket is provided with a peaked upper surface to engage and seal against an adjacent plate. 5. A heat transfer plate according to claim 1 or 2 in combination with a gasket according to claim 3 or 4. 6 A heat transfer apparatus comprising a pack of plates according to claim 5.

Inventors: EVANS, GEOFFREY RICHARD, WRIGHT, FELIX WILLIAM LITTLE PADDOCK
Applicants: APV INTERNATIONAL LIMITED
Application year: 1984
Main classification: F28F3
IPC codes: F28F3