PLATE HEAT EXCHANGER

Abstract: A plate heat exchanger comprising a number of plates being so arranged to each other that plate interspaces are created for the media that are to be heat exchanged, which media are conducted to and from the plate interspaces via inlet holes and outlet holes in the plates, the plates being provided with a press pattern in the heat transfer surfaces and pressed gasket grooves around these surfaces. According to the invention the gasket grooves of the plates are so arranged that the end portion of each plate has a neck gasket groove (1a, 3a; 6a, 8a; 11a, 12a; 15a, 16a) and an adjacent part (1b, 3b; 6b, 8b; 11b, 12b; 15b, 16b) of a port gasket groove extending in intermediate plane, i.e. a plane between the bottom plane of the plate and its top plane, such that the plates can be used partly for creating plate interspaces being sealed off by means of an elastic gasket, partly for creating cassettes such that the plate interspace has been sealed off by joining the two plates together.

Description: Plate .Heat Exchanger This invention relates to a plate heat exchanger comprising a number of plates being so arranged to each other that plate interspaces are created for the media that are to be heat exchanged, which media are conducted to and from the plate interspaces via inlet holes and outlet holes in the plates, the plates being provided with a press pattern in the heat transfer surfaces and pressed gasket grooves round these surfaces. 10 Sometimes there is a need preferably by means of welding to join heat exchange plates together in pairs to so called cassettes, for instance when using aggressive media affecting the gasket material which can lead to medium loss. In this connection the 15 weld constitutes the sealing and replaces an elastic gasket in the plate interspace, whereby the aggressive medium does not come into contact with the elastic gasket on its way through the plate interspace. _ ,0 Previously it has not been possible to join common plates by welding which are intended to be sealed by elastic gaskets in the plate interspaces, but it has been necessary to construct particular plates for welding. This fact has led to high costs for tools and stock-keeping. 25 The purpose of the present invention is accordingly to remove the problems connected with known technics. This purpose is achieved according to the invention in a plate heat exchanger of the kind mentioned by way of introduction in that way that 30 the gasket grooves of the plates are so arranged that the end portion of each plate has a neck gasket groove and an adjacent part of a port gasket groove extending in an intermediate plane, i.e. a plane between the bottom plane of the plate and its top plane such that the plates can be used partly for creating plate 35 interspaces sealed off by means of an elastic gasket, partly for creating cassettes such that the plate interspace has been sealed off by joining the plates together. When using only elastic gaskets the plates are turned in a con- • 5 ventional way for making the plate heat exchanger, i.e. every second plate is rotated half a revolution round an axis perpen¬ dicular to the plane of the plate. This means that a front side of a plate will rest against the rear side of the adjacent plate. 10 When making cassettes to a plate heat exchanger every second plate is turned round an axis in the cross direction in the plane of the plate. This means that a front side of. a plate will rest against the front side of an adjacent plate and rear side 15 against rear side, respectively. This is possible if the gasket grooves are designed such that •> they allow joining in the tumbled case and give space for a gasket in the revolved case and at the same time in both these ,g cases give space for inflow and outflow of media in the neck portions of the plates. Furthermore, the plates are designed with a suitable number of contact points so that the plates can give a mechanical support 25 and have the ability to bear a unilateral pressure both in the revolved case and in the tumbled case. The invention shall be described more in detail in connection to the accompanying drawings, in which 30 Fig. la shows the front side of a plate intended for diagonal flow and having a pattern giving low flow resistance, Fig lb shows the front side of a plate intended for diagonal 35 flow and having a pattern giving high flow resistance, Fig. 2a shows the same plate as in Fig. la, Fig. 2b shows the same plate as in Fig. lb but tumbled round an axis in the cross direction in the plane of the plate, Fig. 3a shows the front side of a plate intended for parallel flow and having a pattern giving low flow resistance and Fig. 3b shows the front side of a plate intended for parallel flow and having a pattern giving high flow resistance. In the figures continuous lines represent gasket grooves in bottom plane while the broken lines represent gasket grooves in intermediate plane, in this case a plane lying essentially midway between the bottom plane and the top plane. It ought to be emphasized that the intermediate plane does not need to have this position but can lie more closely to the bottom plane of the plate than its top plane or vice versa. Fig. 1 shows the front side or the gasket sides of the two plates. In this connection Fig. la shows a plate provided with four ports, one port in each corner, and gasket grooves exten¬ ding round the ports and the plate. The gasket grooves are placed in the bottom plane except at the upper, left port and the lower, right port, where the neck gasket groove la, 3a and the adjacent portion lb, 3b of the port gasket groove are placed in intermediate plane. According to Fig. lb the gasket grooves in this plate are arranged somewhat different in relation to the gasket grooves in the plate according to Fig. la. Thus the gasket grooves in the plate according to Fig. lb extend in bottom plane everywhere except at the upper, right port and the lower, left port, where the neck gasket groove 8a, 6a and the adjacent part 8b, 6b of the port gasket groove are positioned in intermediate plane. In both these plates the "adjacent part" constitutes about half the circumference of the port gasket groove^ If a plate interspace shall be created in which a low flow resistance exists only plates of that type shown in Fig. la are used. The lines la and 3a show, as has been mentioned, neck gasket grooves in intermediate plane. When arranging the plates . 5 for elastic gasket, i.e. every second plate is rotated half a revolution round an axis perpendicular to the plane of the plate, the line 3a on one plate will come over the line la on the adjacent plate, the line 2 over the line 4, the line la over the line 3a and the line 4 on one plate over the line 2 on the 10 second plate. Since this means that lines in intermediate plane come over lines in intermediate plane, and that lines in bottom plane come over lines in bottom plane, the distance between two adjacent plates at these neck gasket grooves will be one "plate distance" , that is the same as the normal distance between two 15 adjacent plates. The flow in the plate interspace can pass via the points lb, la, 3a and 3b. What has accordingly been said regarding two plates according to Fig. la for elastic gasket will also be valid for two plates - P according to Fig. lb for elastic gasket. In the later case, however, a plate interspace is created in which a high flow resistance exists. When creating plate interspaces, in which a flow resistance 25 shall exist lying essentially midway between low and high, both plates according to Fig. la, b are used. If the plate according to Fig. lb is rotated half a revolution round an axis perpendi¬ cular to the plane of the plate and is placed on the plate according to Fig. la the line 5 of the plate according to Fig. 30 lb is falling over the line la of the plate according to Fig. la, the line 6a over the line 4, the line 7 over the line 3a and the line 8a over the line 2. In the plate interspace between these two plates there exists a flow resistance lying on an intermediate level. The flow in the plate interspace can pass 35 via the points 9, 4, 2 and 10. Since a gasket groove in inter- mediate plane is placed over a gasket groove in bottom plane in these points, the distance between the plates in the points 9, 4, 2 and 10 will be 1,5 "plate distance". All plate inter¬ spaces in this case will get this distance in the neck portions . where the flow goes. At the lines 5/la and 7/3a a gasket groove is placed in bottom plane over a gasket groove in intermediate plane, having the consequence that the distance between the plates in these points (that is the gasket space) will be only 0,5 "plate distance". When creating cassettes comprising two plates joined to each other preferably by means of welding the bottom plane of the gasket groove of one plate has to rest against the bottom plane of the gasket groove of the second plate. This means that one plate must be rotated half a revolution round an axis in the cross direction in the plane of the plate. According to Fig. 2b this has happened to the plate shown in Fig. lb, wherefore Fig. 2b shows the rear side of this plate while Fig. 2a shows the front side of the second plate. If now the plate according to Fig. 2a is moved onto the plate according to Fig. 2b the broken lines on the plate according to Fig. 2a will fall over the broken lines of the plate according to Fig. 2b. The same will be valid for the continuous lines. This means that the continuous lines, the bottoms of the gasket grooves, come in contact with each other. The plates can now be welded together along the gasket grooves which are in contact with each other (continuous, thick lines in Fig. 2b). Inside the created cassette the flow from one port to the diagonally positioned port can stream over the neck portions where the gasket grooves are positioned in intermediate plane (broken lines). The distance between the plates at these neck gasket grooves is 1 "plate distance". The cassette now described has been created by means of two different plates, one with low flow resistance and with a gasket groove extending in a certain way and another plate with high flow resistance and with a gasket groove extending in another way. Due to that fact the flow resistance in the space between the plates of the cassette will be on an intermediate level. A cassette can also be created by two plates having the same pattern (low flow resistance and high flow resistance, alter¬ natively), the gasket groove of one plate extending as in Fig. la and the gasket groove of the second plate extending as in Fig. lb. 10 By studying the drawing and imagining the situation with a tumbled plate it is easily understood that a cassette comprising two plates welded to each other cannot in this case be created by two identical plates. 15 The described apparatus is intended for diagonal flow. The invention idea, however, can also be applicated on plates which between themselves create a space in which parallel flow exists. In Fig. 3 there is shown the front side of two different plates, one (3a) with pattern for low flow resistance and the second one (3b) with pattern for high flow resistance. Even in this case continuous lines in the drawing represent gasket groove in bottom plane while broken lines represent gasket groove in 25 intermediate plane, In this case a plane midway between the bottom plane of the plate and Its top plane. As has been shown in the drawing the plate according to Fig. 3a has gasket grooves extending in bottom plane except at the upper 30 left port and the lower left port where the neck gasket groove 11a, 12a and the adjacent portion lib, 12b of the port gasket groove are placed In intermediate plane. In Fig. 3b there is shown a plate the gasket groove of which extends in exactly the same way as in the plate according to Fig. 3a. The only diffe- 35 rence is the design of the pattern in the primary heat exchange surface of the plate. In both these plates "the adjacent part" constitutes about half the circumference of the port gasket groove. 5 If a plate interspace shall be created in which a low flow resistance exists only plates of that type shown in Fig. 3a are used. When arranging the plates for elastic gasket, i.e. every second plate is revolved round an axis perpendicular to the plane of the plate the continuous line 13 on one plate will come 10 over the broken line 11a on adjacent plate (distance between the plates: 0,5 "plate distance"), the broken line 12a over the continuous line 14 (distance between the plates: 1,5 "plate distance"), the broken line 11a over the continuous line 13 (distance between the plates: 1,5 "plate distance") and the 15 continuous line 14 over the broken line 12a (distance between the plates: 0,5 "plate distance"). The flow through the created plate interspace will pass via the points 19, 14, 13 and 20. ^20 If a plate interspace is to be created in which a high flow resistance shall exist instead two plates of that type shown in Fig. 3b are used. If a plate interspace is to be created where the flow resistance is on an intermediate level the plates 25 according to Fig. 3a, b are combined. The distance between the plates in the neck portions of the plate interspaces will in both these later cases be the same as has been shown for the plate interspace created by two plates according to Fig. 3a. 30 When creating cassettes comprising two plates welded to each other the bottom plane of the gasket groove in one plate has to rest against the bottom plane of the gasket groove in the other plate. This means that one of the plates has to be rotated half a revolution round an axis In the cross direction in the plane 35 of the plate. Due to the fact that the gasket grooves extend in that way mentioned previously, which is the same for the two plates according to Fig. 3a, b this will mean that three cassettes having different flow resistance can be created, namely 5 1) cassette comprising two plates according to Fig. 3a 2) cassette comprising two plates according to Fig. 3b 0 3) cassette comprising one plate accordig to Fig. 3a and one plate according to Fig. 3b. In all three cases the broken lines of one plate will come over the broken lines of the second plate and the continuous lines 5 of one plate will come over the continuous lines of the second plate. This means that the continuous lines, the bottoms of the gasket groove, come in contact with each other. The plates can • now be welded together along the bottoms of the gasket groove which are in contact with each other (continuous, thick lines in _0 Fig. 3b). Inside the created cassette the flow from one port by means of parallel flow can stream to another port over the neck portions where the gasket grooves are placed in an intermediate plane (broken lines). The distance between the plates at these neck gasket grooves is 1 "plate distance" . 5 According to the described embodiments welding is suggested when joining the two plates together to a cassette. The invention, however, is not limited to that joining method, but also other joining methods can be used as for instance soldering or glueing.

Claims: Claims 1. Plate heat exchanger comprising a number of plates being so . arranged to each other that plate interspaces are created for the media that are to be heat exchanged, which media are conduc¬ ted to and from the plate interspaces via inlet holes and outlet holes in the plates, the plates being provided with a press pattern in the heat transfer surfaces and pressed gasket grooves round these surfaces, c h a r a c t e r i z e d i n that the gasket grooves of the plates are so arranged that the end portion of each plate has a neck gasket groove (la, 3a; 6a, 8a; 11a, 12a; 15a, 16a) and an adjacent part (lb, 3b; 6b, 8b; lib, 12b; 15b, 16b) of a port gasket groove extending in an inter¬ mediate plane i.e. a plane between the bottom plane of the plate and its top plane such that the plates can be used partly for creating plate interspaces sealed off by means of an elastic gasket partly for creating cassettes such that- the plate- inter¬ space has been sealed off by joining the plates together. 2. Plate heat exchanger according to claim 1 provided with plates made for diagonal flow, c h a r a c t e r i z e d i n that at least a first plate (Fig. la) is so designed that its gasket groove extends in bottom plane everywhere except at two diagonally placed corner areas, where the neck gasket groove (la, 3a) and the adjacent part (lb, 3b) of che port gasket groove extends in intermediate plane and that at least another plate (Fig. lb) for cooperation with the first one is so designed that its gasket groove extends in bottom plane every¬ where except at two corner areas, which are reversed in relation to those at the first plate, where the neck gasket groove (8a, 6a) and the adjacent part (8b, 6b) of the port gasket groove extend in intermediate plane. 3. Plate heat exchanger according to claim 2, the plate inter¬ space between two plates being sealed off by means of an elastic gasket, c h a r a c t e r i z e d i n that both plates (Fig. la, b) are provided with a pattern for low flow resistance. 5 alternatively high flow resistance or one of the plates (Fig. la) is provided with a pattern for low flow resistance and the second one (Fig. lb) with a pattern for high flow resistance. 4. Plate heat exchanger according to claim 2, the plate inter- 0 space between two plates being sealed off by joining the plates together, c h a r a c t e r i z e d i n that one of the plates (Fig. la) is provided with a pattern for low flow resis¬ tance and the second one (Fig. lb) with a pattern for high flow resistance. 5 5. Plate heat exchanger according to claim 1 provided with plates made for parallel flow, c h a r a c t e r i z e d i n that at least a first plate (Fig. 3a) and a second plate (Fig. 3b) are so designed that their gasket grooves extend in ^ 0 bottom plane everywhere except at two corner areas, one at the upper portion of the plate and one at the lower portion of the plate on the same side of the longitudinal centre line of the plate, where the neck gasket groove (11a, 12a; 15a, 16a) and the adjacent part (lib, 12b; 15b, 16b) of the port gasket groove 5 extend in intermediate plane. 6. Plate heat exchanger according to claim 5, the plate inter¬ space between two plates being sealed off by means of an elastic gasket, c h a r a c t e r i z e d i n that both plates are 0 provided with a pattern for low flow resistance alternatively high flow resistance or one (Fig. 3a) of the plates is provided with a pattern for low flow resistance and the second one (Fig. 3b) with a pattern for high flow resistance. 7. Plate heat exchanger according to claim 5, the plate inter¬ space between two plates being sealed off by joining the plates together, c h a r a c t e r i z e d i n that both plates are provided with a pattern for low flow resistance alterna- tively high flow resistance or one (Fig. 3a) of the plates is provided with a pattern for low flow resistance and the second one (Fig. 3b) with a pattern for high flow resistance. 8. Plate heat exchanger according to anyone of the preceding claims, c h a r a c t e r i z e d i n that the inter¬ mediate plane is placed midway between the bottom plane of the plate and its top plane. 9. Plate heat exchanger according to anyone of the preceding claims, c h a r a c t e r i z e d i n that the joining of the two plates together to a cassette is made by means of welding.

Inventors: STADMARK NILS, STADMARK, NILS
Applicants: ALFA LAVAL THERMAL, ALFA-LAVAL THERMAL AB
Application year: 1986
Main classification: F28F3
IPC codes: F28F3