A PLATE HEAT EXCHANGER HAVING A WEDGE-SHAPED GASKET

Abstract: A plate heat exchanger comprising a plurality of stacked heat exchanger plates (1; 11) which each have four through openings (3, 4). The plate heat exchanger moreover comprises gaskets (2; 12) which, on one side of each plate (1; 11), define a first flow area (5) comprising two through openings (3) for a first heat exchanger medium, while the two other openings (4) are blocked, and, on the other side of the plate (1; 11), define a second flow area which has essentially the same extent as the first flow area (5), and which comprises two other through openings (4) for a second heat exchanger medium, while the two first openings (3) are blocked. The stacked heat exchanger plates (1; 11) thus form a plate heat exchanger having at least one area (7, 8) for each plate (1; 11) which is just provided with gaskets (2; 12) on one side. The gasket (2; 12), at least in an area in which gaskets (2; 12) are just provided between every second plate (1; 11), has a cross section which is wedge-shaped over a considerable part of the width of the gasket with the widest side facing the heat exchanger medium and the narrowest side facing away from the heat exchanger medium, and in this area each heat exchanger plate (1; 11) has a complementarily shaped gasket groove (6; 14, 15) to support the gasket (2; 12).

Description: A plate heat exchanger having a wedge-shaped gasket The invention relates to a plate heat exchanger compris ¬ ing a plurality of stacked heat exchanger plates which each have four through openings, and gaskets which, on one side of each plate, define a first flow area compris ¬ ing two through openings for the first heat exchanger me ¬ dium, while the two other openings are blocked, and, on the other side of the plate, define a second flow area which has essentially the same extent as the first flow area, and which comprises two other flow openings for the second heat exchanger medium, while the two first openings are blocked, so that the stacked heat exchanger plates form a plate heat exchanger having at least one area for each plate which is just provided with gaskets on one side. Such heat exchanger plates are generally known from e.g. WO 88/03253, which discloses a plate heat exchanger com- prising a plurality of heat exchanger plates having through openings defining inlet ports and outlet ports for two heat exchanger media, and rubber gaskets arranged between the heat exchanger plates. Each rubber gasket de ¬ fines a flow area between two heat exchanger plates, said flow area comprising two openings which constitute an inlet port and an outlet port for a first heat exchanger medium, while it seals off the flow area from the other openings in the heat exchanger plates. Each of these other openings is provided with a ring-shaped rubber gas- ket to define a flow opening between two heat exchanger plates. The rubber gasket sealing off the flow area may be connected with the ring-shaped rubber gaskets around the two other holes by means of connecting members, which, however, do not seal tightly between the plates. It is generally known that the most difficult place to achieve a leakage-proof gasket is in the area between the flow area and the blocked opening - the so-called bridge area - as, in this area, the plate heat exchanger just contains one gasket between every second heat exchanger plate. This means that the plates of the plate heat exchanger tend to deflect in this area when the plate heat exchanger is pressurized in operation, which, of course, leads to an increased risk of leakage in precisely this area. If a leakage occurs in the bridge area, the leaking medium will flow out in the area between the bridge area and the ring-shaped gasket, following which it will be conveyed to the outer side of the heat exchanger where it may be detected. The area between the bridge area and the ring-shaped gasket is therefore also called the drain area or the drained area. Many attempts have been made at reinforcing the heat exchanger plates in the areas where there is just one gas- ket between every second plate, with the purpose of minimizing the deflection when the heat exchanger is pressurized. In the plate heat exchangers shown in GB-A-2 128 726 and US-A-4 635 714, the gasket groove for the rubber gasket is corrugated so that this portion of the plate obtains a greater rigidity. This approach, however, makes great demands on the structure of the gasket itself, as this must conform closely to the corrugations of the plate to ob- tain an optimum gasket, which means that the cost price of the gasket is relatively high. In the plate heat exchangers shown in US-A-3 792 730, US- A-4 063 591 and US-A-4 660 633, the plates are arranged so as to rest against each other on the sides where there are no gaskets in order to prevent the individual plate from deflecting in this area. As in this approach some of the plate material is used for forming elevations on the side of the plate which is opposite the gasket, less ma ¬ terial is available to form the gasket groove, which re- suits in an increased risk of the gasket being pressed out of the gasket groove when pressure is applied to the plate heat exchanger. Furthermore, there is a limit to the amount of material that can extend into the area without a gasket, since there must be a passage for a heat exchanger medium on this side of the heat exchanger plate . The object of the present invention is to provide a plate heat exchanger which minimizes the risk of leakage in the areas in which gaskets are just provided between every second heat exchanger plate. This is achieved by arranging the plate heat exchanger mentioned in the opening paragraph such that the gasket, at least in an area in which gaskets are just provided between every second plate, has a cross-section which is wedge-shaped over a considerable part of the width of the gasket with the widest side facing the heat exchanger me ¬ dium and the narrowest side facing away from the heat ex- changer medium, and that each heat exchanger plate in this area has a complementarily shaped gasket groove to support the gasket. When the plate heat exchanger is arranged in this manner, it is ensured that while an increased pressure from the heat exchanger medium will try to deflect the heat exchanger plates in the areas in which there is just a gasket on one side and try to press the gaskets out of the gasket grooves, the gaskets will merely wedge themselves even more firmly between the plates, since the gaskets in said areas are wedge-shaped and the gasket grooves are shaped complementarily . This minimizes the risk of leak ¬ age in these areas compared to the known plate heat exchangers . As mentioned previously, the most difficult place to ob ¬ tain a leakage-proof gasket in the known plate heat ex ¬ changers in which the gaskets are positioned essentially directly opposite each other on each side of the heat ex ¬ changer plate, is in the so-called bridge area in which there just one gasket for every second plate heat ex ¬ changer. In a preferred embodiment for use in this type of plate heat exchangers, the gaskets are therefore just wedge-shaped in the bridge areas which adjoin the flow area in the areas at the blocked openings . In another embodiment, the gaskets are also positioned essentially directly opposite each other on each side of the heat exchanger plates, and in this embodiment the gaskets are just wedge-shaped in the areas around the blocked openings which face the flow area, since also in this area there is just one gasket between every second heat exchanger plate. The gaskets may also be wedge-shaped in both the bridge areas which adjoin the flow area in the areas at the blocked openings and in the areas around the blocked openings which face the flow area. If the plate heat exchanger is arranged such that the gaskets are staggered with respect to each other on each side of the heat exchanger plates, they may be wedge- shaped over their entire length. It is ensured hereby that the plate heat exchanger is sealed in the same manner everywhere, and that, in principle, it therefore has no areas which are more critical with respect to leakage than others . It applies to all the mentioned embodiments that the heat exchanger plates according to the invention are provided with a gasket groove shaped complementarily to the gas- ket. The invention will now be explained more fully with ref ¬ erence to the drawing, in which fig. 1 shows a traditional structure of a plate heat ex ¬ changer with heat exchanger plates and gaskets, fig. 2 shows a heat exchanger plate with gaskets, fig. 3 shows a section along the line A-A in fig. 2, fig. 4 shows a heat exchanger plate with a staggered ar ¬ rangement of gaskets, and fig. 5 schematically shows a section along the line B-B in fig. 4. Fig. 1 shows a traditional structure of a plate heat exchanger which comprises a row of identical heat exchanger plates 1 and a plurality of identical gaskets 2 arranged between the plates 1. Each plate 1 is provided with four through openings 3 and 4 which define inlet and outlet ports for a first heat exchanger medium and a second heat exchanger medium, respectively. In the preferred embodi- ment, the plates 1 consist of corrugated metal plates of e.g. stainless steel. In fig. 1, the corrugations are shown in the flow area 5 of the plates 1, but the plates may also be provided with corrugations in the end areas around the inlet and outlet holes 3, 4. The corrugations serve to convey the heat exchanger media toward the flow areas 5 and to provide support for the plates 1 when these are stacked and clamped to form a plate heat ex ¬ changer . In the preferred embodiment, the plates 1 are provided with a gasket groove 6 on one side to hold a gasket 2 which will engage the opposite side of the gasket groove 6 when the plates 1 are clamped together to form the plate heat exchanger. The gasket groove 6 consists of a plane area between the corrugations of the plate 1. As will appear from fig. 1, the plates 1 and the gaskets 2 are alternately turned 180°, so that a first heat ex ¬ changer medium flows on one side of each plate 1, while a second heat exchanger medium flows on the other side, thereby achieving heat exchange across the plates 1. Fig. 2 shows a heat exchanger plate 1 provided with a gasket 2 which extends around the flow area 5 and two inlet/outlet holes 3 so that a first heat exchanger medium has access to the flow area 5. The gasket 2 blocks the other two inlet/outlet holes 4 so that the second heat exchanger medium does not have access to this side of the plate 1. On the opposite side of the plate 1, the gasket 2 (and the succeeding plate 1) is turned 180°, as shown in fig. 1, which means that the gasket 2 on this opposite side extends as shown in dashed line, so that it blocks the inlet/outlet holes 3, while the inlet/outlet holes 4 and the flow area 5 communicate. The gaskets 2 are preferably positioned directly opposite each other when the plate heat exchanger is assembled, but since the inlet/outlet holes 3, 4 alternately communicate with the flow area 5, there will be areas in which there are just gasket parts for every second plate 1. This applies to e.g. the so-called bridge area 7 and to the part 8 of the gasket 2 around the blocked in- let/outlet hole 4 which faces the flow area. Since, fol ¬ lowing assembly of the plate heat exchanger, the plates 1 are just supported in these areas between every second plate 1, the plates 1 tend to deflect in these areas when the plate heat exchanger is pressurized in operation. This is particularly problematic in connection with the bridge area 7 which has a relatively long extent. Traditionally, the deflection in the bridge area is mini- mized by corrugating the plate 1 close to the gasket 2, so that two plates 1 without a gasket 2 may adjoin each other in this area to compensate for the absence of a gasket 2. However, flow of the second heat exchanger medium must still be possible between the plates 1, which puts a limit to the degree of corrugation. Moreover, this corrugation also has the effect that less material is available to hold the gasket 2, thereby increasing the risk of the gasket being pressed out of the gasket groove 6. Fig. 3 shows a section along the line A-A in fig. 2 when several plates 1 are stacked to form a plate heat exchanger in a preferred embodiment of the invention. As will appear, the gasket 2 has a cross-section in the bridge area 7 which is substantially wedge-shaped over the entire width. The gasket 2 is positioned in a gasket groove 6 in the plates 1, and this gasket groove 6 has a shape complementary to the gasket 2. In fig. 3, corrugations are shown on both sides of the gasket groove 6, which partly contribute to holding the gasket 2 in the gasket groove 6 and partly support the plates 1 against each other and impart rigidity to the plates 1. In addition to being wedge-shaped over most of its width, the gasket 2 is shaped such that it closely matches the corrugations of the plates 1. Fig. 4 shows an alternative heat exchanger plate 11 with staggered gasket grooves on each side, so that on one side of the plate 11 (shown in solid line) the gasket 12 is staggered with respect to an identical gasket 12 turned 180° on the other side (shown in dashed line) . When the gasket 12 is positioned in this manner with re ¬ spect to the plate 11, it may be wedge-shaped over its entire extent, it being possible to provide the plate 11 with oppositely directed inclined faces to form staggered gasket grooves on each side of the plate 11. This is shown in more detail in fig. 5, which shows a basic section along the line B-B in fig. 4 and illustrates the structure of a plate heat exchanger with staggered gaskets 12 positioned in staggered gasket grooves 13, 14 on each side of the plate 11 to support the gaskets 12. As will appear, in the embodiment shown, one side (the upper side) of the gaskets 12 extends in parallel with the extent of the heat exchanger plates 11, while the other side (the underside) extends obliquely with respect thereto, so that the cross-section as a whole is wedge- shaped.

Claims: P a t e n t C l a i m s 1. A plate heat exchanger comprising a plurality of stacked heat exchanger plates (1; 11) which each have four through openings (3, 4), and gaskets (2; 12) which, on one side of each plate (1; 11), define a first flow area (5) comprising two through openings (3) for a first heat exchanger medium, while the two other openings (4) are blocked, and, on the other side of the plate (1; 11), define a second flow area which has essentially the same extent as the first flow area (5) , and which comprises two other through openings (4) for a second heat exchanger medium, while the two first openings (3) are blocked, so that the stacked heat exchanger plates (1; 11) form a plate heat exchanger having at least one area (7, 8) for each plate (1; 11) which is just provided with gaskets (2; 12) on one side, c h a r a c t e r i z e d in that the gasket (2; 12), at least in an area in which gaskets (2; 12) are just provided between every second plate (1; 11), has a cross-section which is wedge-shaped over a considerable part of the width of the gasket with the widest side facing the heat exchanger medium and the narrowest side facing away from the heat exchanger me- dium, and that each heat exchanger plate (1; 11) in this area has a complementarily shaped gasket groove (6; 14, 15) to support the gasket (2; 12) . 2. A plate heat exchanger according to claim 1, c h a r a c t e r i z e d in that the gaskets (2) are positioned essentially directly opposite each other on each side of the heat exchanger plates (1), and that they are just wedge-shaped in the bridge areas (7) which adjoin the flow area (5) in the areas at the blocked open- ings (4) . 3. A plate heat exchanger according to claim 1, c h a r a c t e r i z e d in that the gaskets (2) are positioned essentially directly opposite each other on each side of the heat exchanger plates (1), and that they are just wedge-shaped in the areas (8) around the blocked openings (4) which face the flow area (5) . 4. A plate heat exchanger according to claim 1, c h a r a c t e r i z e d in that the gaskets (2) are positioned essentially directly opposite each other on each side of the heat exchanger plates (1), and that they are wedge-shaped in both the bridge areas (7) which ad ¬ join the flow area (5) in the areas at the blocked openings (4), and in the areas (8) around the blocked open- ings (4) which face the flow area (5) . 5. A plate heat exchanger according to claim 1, c h a r a c t e r i z e d in that the gaskets (12) are staggered with respect to each other on each side of the heat exchanger plates (11), and that they are substantially wedge-shaped over their entire length.

Inventors: HANSEN PETERSEN JES, JENSEN BENNY, PEDERSEN ELLGAARD SOEE, HANSEN PETERSEN, JES, JENSEN, BENNY, PEDERSEN, ELLGAARD, SOEE
Applicants: APV HEAT EXCHANGER AS, HANSEN PETERSEN JES, JENSEN BENNY, PEDERSEN ELLGAARD SOEE, APV HEAT EXCHANGER A/S, HANSEN PETERSEN, JES, JENSEN, BENNY, PEDERSEN, ELLGAARD, SOEE
Application year: 1999
Main classification: F28F3
IPC codes: F28F3