GASKET FOR A PLATE HEAT EXCHANGER

Abstract: Gasket for a plate heat exchanger intended to be applied between two adjacent plates forming part of the heat exchanger, the space between the plates forming a passage for a heat exchanging medium. The invention is characterized in that the gasket comprises a wire (3) of hard and essentially inelastic material, which essentially bridges the distance between the two plates (1), and that the wire (3) at least in certain places along its extension is connected with the plates (1) in such a way that the heat exchanging medium cannot pass the wire (3).

Description: Gasket for a ' plate heat exchange!: This invention relates to a gasket for a plate heat exchanger intended to be applied between two adjacent plates forming part of the heat exchanger, the space between the plates forming a passage for a heat exchanging medium. A plate heat exchanger comprises several plates as a rule mounted in a frame and mainly rectangular, which plates are tightened from each other by means of edge gaskets and between which are formed heat transfer areas in the form of parallel-connected heat exchanging passages for through-flow of heat exchanging media, which are conducted to and from the heat exchanger via inlets and outlets arranged at one of its ends, the plates at their corner parts being provided with openings for forming inlet channels and outlet channels for the heat exchanging media. * Such plate heat exchangers are manufactured in different sizes with plates the heat transfer areas of which can range- from some few square decimeters to several square meters. The plate material is chosen with regard to the field of use but usually comprises stainless or acid-resistant steel. For certain purposes titanium is used, which has excellent resistance against salt water but is very expensive. The edge gaskets sealing between the plates essentially consist of rubber of varying qualities. The sealing pressure of the rubber gaskets is received when the plate package is tightened by the frame by means of set bolts and is maintained by the elasticity of the rubber. A plate heat exchanger can be easily dismantled and inspected or cleaned and thereafter tightened again as long as the gaskets maintain their elasticity and their form. At moderate temperatures, below 70-80°C, the gaskets have as long life as 5-8 years. At higher temperatures, more than 100°C, however, the gaskets sink in and lose their original form and by that their sealing capability. Under such circumstances the gaskets have to be exchanged once per year or still more often, which is an expensive procedure. The limitation of the gasket as to temperature and life makes it to the weak link of the plate heat exchanger. According to a known solution shown in the German patent publication 1.149.027 the gasket between the plates of the heat exchanger consists of an elastic gasket with a round cross section. In order to prevent that the gasket is squeezed together too strongly it cooperates with two firm, separate organs, one on each side of the gasket, both of which have a round cross section. The known apparatus is connected with several drawbacks. Firstly, it is unnecessarily complicated and expensive, since it contains three separate elements. Secondly, the apparatus requires a broad gasket groove, i.e. a large, lateral space, which injuriously encroaches upon the heat surface of the heat exchanger plates. Thirdly, the sealing capability of the apparatus will cease if the heat exchanging medium has a high temperature, since the elastic gasket then loses its elasticity. According to another known solution (DE-AS 1.207.947) the sealing apparatus consists of elastic elements which are put into a holder of an inelastic material, which follows the outer edges of the heat exchanger plates. Even this apparatus occupies a relatively large, lateral space and limits in that way the heat surface of heat exchanger plates. Further, the apparatus is of such a nature that one type of holder is required for each size of the heat exchanger plate, which means a great cost for this sealing apparatus. Moreover, the elastic strings in the holder are subjected to external influence when using hot heat exchanging OMPI media, which means short life for the elastic strings under hard conditions. This invention intends to remove the problems that are connected with known technics. This is made possible by a gasket of the kind mentioned by way of introduction, which is characterized in that it comprises a wire of hard and essentially inelastic material, which essentially bridges the distance between the two plates and that the wire at least at certain places along its extension is connected with the plates in such a way that the heat exchanging medium cannot pass the wire. The invention shall hereafter be described more closely in connection with the accompanying drawing which as examples shows some embodiments of the invention. In the drawing there are shown heat exchanger plates 1 provided with grooves 2 into which a sealing element 3 is applied. The sealing element 3 is intended to constitute a seal between two adjacent plates 1 for a medium streaming in the channel 4 between these plates 1. The sealing elements 3 comprises a round wire which is preferably made of the same metallic material as the plates and functions as a bridging component between the plates 1. When applying the metal wire 3 this one is put into the gasket groove 2 and is formed in accordance with the form of the groove in the plates. The round metal profile allows itself to be easily bent without having its cross section deformed. The metal wire 3 is joined to final form preferably by butt welding, whereafter the weld joint is ground. The material metal is mentioned but another hard and resistant material can be used. Likewise, the wire profile can have another form than round. A thin-walled metal tube is preferably used, which one can be somewhat more flexible than a solid metal wire. The bridging metal wire 3 shall have a diameter that mainly corresponds to the distance between two adjacent plates 1. The wires in the different channels in a plate package support each other in great parts of the gasket grooves but not at the ports, where every second gasket is taken away so that a liquid can stream into the channels. Thus , the sealing pressure metal wire-plate surface is low in certain parts of the sealing length, and, therefore, the metal wire cannot independently manage the sealing against the plates. Therefore, the sealing function of the metal wire ought to be improved at least in these places. This sealing function can be arranged in several ways: A) Connection of the wire with the plates by means of a soft material, for instance rubber, teflon and/or plastics material, the wire being coated with the soft material; B) Connection of the wire with the plates by means of a soft material, for instance rubber, teflon and/or plastics material, the sealing surfaces of the plates being coated with the soft material; The coating with the soft material according to A) and B) is preferably made in such a way that when applying the wire between the plates the wire is attached to the plates. C) Connection of the wire with the plates by means of I) a temperature- and liquid resistant glue; II) soldering; III) welding. The different ways A-C are shown in the drawing, where the connection coating is denoted by the figure 5 and the joint connections in the form of glued joint, soldered seam or weld joint by the figure 6. In certain applications the metal wire is connected with the plates along all its length. In those cases when the whole metal wire is connected with the plates by means of soldering the connection is preferably made in the following way: The metal wire is put into the gasket groove of the plate, whereafter the plate with wire is covered by a soldering sheet. On the top of this is put a new plate with wire and a soldering sheet and so on. When heating in a suitable way the soldering sheet melts and through influence of the capillary force the solder flows into the rooms between the metal wire and the plates, The metal wires need not lie in the same plane and support each other but can also lie displaced in relation to each other in the gasket grooves, the material of the plate being able to yield and take up movements, when the wires expand during heating. There are several advantages connected with this described sealing apparatus. Firstly, the sealing apparatus is very simple and cheap both to produce and apply. Secondly, the sealing apparatus only requires a narrow gasket groove, whereby only an exceedingly small encroaching upon the heat surface of the heat exchanger plates OMPI ■ WlPθ is made. Thirdly, the sealing apparatus in contrast to conventional rubber gaskets is very suitable to use in heat exchangers for hot and aggressive media. The reason why is that the main component of the gasket comprises a wire that bridges the distance between the plates, which wire is preferably made of metal and at least at certain places cooperates with a connection material. -BUKtA T

Claims: Claims 1. Gasket for a plate heat exchanger intended to be applied between two adjacent plates forming part of the heat exchanger, the space between the plates forming a passage for a heat exchanging medium, c h a r a c t e r i z e d i n that it comprises a wire (3) of hard and essentially inelastic material, which essentially bridges the distance between the two plates (1) , and that the wire (3) at least in certain places along its extension is connected with the plates (1) in such a way that the heat exchanging medium cannot pass the wire (3). 2. Gasket according to claim 1, c h a r a c t e r i z e d i n that the wire (3) is flexible and put into a groove (2) of one of the plates (1) , the wire being formed in accordance with the form of the groove (2). 3. Gasket according to claim 1 or 2, c h a r a c t e r i z e d i n that the wire (3) comprises a thin-walled metal tube. 4. Gasket according to anyone of the preceding claims, c h a ¬ r a c t e r i z e d i n that the cross-section of the wire (3) has the form of a circle. 5. Gasket according to anyone of the preceding claims, c a ¬ r a c t e r i z e d i n that the wire (3) is connected with the plates (1) by means of a soft material (5) like rubber, teflon and/or plastics material, the wire (3) being coated with the soft material (5). 6. Gasket according to anyone of the claims 1-4, c h a r a c ¬ t e r i z e d i n that the wire (3) is connected with the plates (1) by means of a soft material (5) like rubber, teflon and/or plastics material, the sealing surfaces of the plates (1) being coated with the soft material (5). 7. Gasket according to anyone of the claims 1-4, c h a r a c ¬ t e r i z e d i n that the wire (3) is connected with the plates (1) by means of glue. 8. Gasket according to anyone of the claims 1-4, the wire (3) comprising a metallic material, c h a r a c t e r i z e d i n that the wire (3) is connected with the plates (1) by means of solder. 9. Gasket according to anyone of the claims 1-4, the wire (3) comprising a metallic material, c h a r a c t e r i z e d i n that the wire (3) Is connected with the plates (1) by means of a weld joint. 10. Gasket according to claim 8 or 9, c h a r a c t e r i z e d i n that the wire (3) is connected with the plates (1) along all Its length.

Inventors: DAHLGREN JOENS ARTHUR, KAELLROT MAGNUS, DAHLGREN, JOENS, ARTHUR, KAELLROT, MAGNUS
Applicants: ALFA LAVAL THERMAL, ALFA-LAVAL THERMAL AB
Application year: 1984
Main classification: F28F3
IPC codes: F28F3