PLATE HEAT EXCHANGER

Abstract: The present invention relates to a plate heat exchanger with a gasket positioned between the heat exchanger plates. The entry and outlet region from the entry and exit openings of the heat exchanger plates form a problem area, since, in this region, a gasket exists only in every second channel. Hereby, leaks may occur in this region. From the prior art solutions for avoiding or reducing the leaks in the outlet region of the entry and exit openings of the heat exchanger plates are known. In all these solutions the gaskets are still accomodated in a gasket groove. The object of the present invention is to avoid the leakiness in this region while obviating a gasket groove associated with disadvantages. According to the invention, this object is achieved, in that the corrugation extending from the entry and exit openings (8, 9) of the heat exchanger plates (1, 2) extends in a substantially radial direction to the heat exchanger surfaces (7) and thereby uninterrupted traverses the region of the extent (10) of the gasket and crosses the corresponding corrugations of the adjacent heat exchanger plates (1, 2), such that the extent (10) of the gasket is flanked on both sides by the crossing points (12) of the corrugation hills (11) of one plate (1) with the corrugation troughs of the other plate (2), the gasket (15) arranged between the heat exchanger plates (1, 2) varying in cross section to be adapted to the profile of the heat exchanger plates (1, 2) in this region, such that substantially the same specific gasket pressure is obtained over the whole extent (10) of the gasket in a compressed condition. The present invention also provides a method of producing a plate heat exchanger wherein the gasket is vulcanized in a vulcanization press using a heat exchanger plate as a press mould in the vulcanization press.

Description: APPLICANT: TAU ENERGY PRODUCTS AB AND LARS PERSSON TITLE OF INVENTION: PLATE HEAT EXCHANGER The present invention relates to a plate heat exchanger comprising alternately arranged plates compressed together O -?. — C , f TT.Z.π Z ^ ZZ Zl C-.-.C-ΓUIC .-. G >_. iucαna s_, yd!->λ.--: ι_ .-> arranged between the plates, alternately for a heat emitting and a heat absorbing medium. These channels may be supplied with the respective medium through entry and exit openings in the plates aligned with each other, profiles extending from the entry and exit openings, and in the region of these profiles, gaskets for separating the entry and exit open¬ ings, respectively, from the heat exchanger surfaces are arranged alternately between pairs of plates . The gaskets of plate heat exchangers of this type are usually arranged in flat gasket grooves supporting the gas¬ ket laterally. In a known way, the intake and outlet region of the entry and exit openings on the heat exchanger sur¬ faces as such form the weakest points of the gasket. In this region, a gasket is arranged only in every second channel while the heat transferring medium encountering the adjacent plate flows in each interposed channel, the gasket groove forming an undesired flow resistance. In the region under- flowed in this way, the gasket groove bottom does not obtain a sufficient metallic support. Since it is also flat and not embossed in the conventional way, it may deform plastically and elastically, locally reducing the gasket pressure. The reduced gasket pressure results in that a leakage may occur in this region even at lower pressures of the heat exchange medium as well as in other regions of the gasket. From the state of the art, structures and measures, respectively, for mitigating or reducing the leakiness in the flow region of the entry and exit openings of the plate are known. A known measure consists in partially enlarging the gasket in this region. However, this possibility is lim- ited, since a plastic deformation of the gasket groove bottom still will occur. Another solution is disclosed in DE-AS-23 09 743. Here a lateral support of the gasket groove bottom is obtained by a suitable embossmen . The patent document DE 32 39 004 C2 discloses another solution approach. Here the gasket groove bottom is reinforced by additional embossments. The solution according to GB-PS 1 020 045 goes further than the solutions mentioned above, in that the embossments of the gasket groove bottom is metallically supported by the respective following plate, however, without adapting the form of the gasket to the embossment. In GB 2 128 726 A, a gasket is also fillingly adapted to the embossment. With this state of the art, the problem of the tightness in the outlet region of the entry and exit openings is solved in a satisfactory manner. However, in all these solu¬ tions the known gasket groove remains in its basic form and the advantage of the direct support is traded against a reduction of the flow cross-section for the entering and exiting medium. Thus, according to a first aspect of the present inven¬ tion, the object of the present invention is to provide a plate heat exchanger of the above described type, wherein a safe seal is obtained while obviating a conventional gasket groove in the outlet region of the entry and exit openings of the heat exchanger plates. According to a second aspect of the present invention, a further object of the present invention is to provide a plate heat exchanger wherein a safe seal is obtained while obviating a conventional gasket groove in the peripheral region of the heat exchanger surfaces of the heat exchanger plates. According to a third aspect of the present invention, a still further object of the present invention is to provide a method of producing a plate heat exchanger wherein the gasket is vulcanized in a vulcanization press using a heat exchanger plate as a press mould in the vulcanization press. According to the first aspect of invention, this object is solved by means of a plate heat exchanger wherein the profiles extending from the entry and outlet openings are extending in a substantially radial direction to the heat exchanger surfaces and thereby continuously traverse the length of the gasket and cross the corresponding profiles of the adjacent plate, such that the extent of the gasket from the crossing point of the corrugation hills of one plate with the corrugation troughs of the other plate is flanked on both sides, whereby the gasket arranged between the plates has a varying cross-section to be adapted to a corru- gation of the plates in this region, so that, in compressed rnni , ϊ t- ϊ on onhot pnt' . a ■ ■ V T- Vio e s>τrιo f;ιn n ■ ! -P - is obtained over the whole extent of the gasket. According to the second aspect of invention, this object is solved by means of a plate heat exchanger wherein the corrugations of the heat exchanger surfaces extend uninter¬ rupted to the edge of the heat exchanger, the peripheral gasket being arranged between the heat exchanger surfaces, such that the extent of the peripheral gasket is flanked on both sides by the crossing points of the corrugation hills of one plate with the corrugation troughs of the other plate, the peripheral gasket arranged between the heat exchanger plates varying in cross-section to be adapted to the profile of the heat exchanger surfaces in this region. According to the third aspect of invention, this object is solved by means of a method of producing a plate heat exchanger wherein the gasket is vulcanized in a vulcaniza¬ tion press using a heat exchanger plate as a press mould. Further embodiments of the invention are defined in the accompanying claims. With respect to the prior art, the present invention obviates completely a specific gasket groove and hence a holohedral gasket space. Instead, by a special configuration of the corrugation in the region of the outlet region of the entry and exit openings and, preferably, in the peripheral region, the gasket is shaped so that the gasket still is flanked laterally, while the tightness is ensured by a special gasket form adapted to this corrugation, the corru¬ gation extending radially from the entry and exit openings to the heat exchanger surfaces and to the edge of the heat exchanger surfaces, respectively. These corrugations cross corrugations shaped in the same way of the adjacent plate. The gasket is adapted to the crossing wave-form formed in this way at both sides, that is the cross-section of the gasket varies corresponding to the profile and is positioned such that, in compressed condition, substantially the same specific gasket pressure is obtained over the whole gasket . Because of the radial configuration of the corrugation the gasket space tapers from the heat exchanger surfaces on which the medium pressure impinges to the entry and exit openings and the gasket is wedged by the working pressure of me ium ■τι t"hip t ιτ~(s -e* -τ- o _σ-_> <τ-τ_ >n vhc C -" it ic additionally supported by the crossing points following thereafter. The claimed invention presents the following advantages over the prior solutions : The uninterrupted continuous corrugation in the region of the gasket causes a high stiffness, whereby the required gasket pressure is ensured in this region. By obviating the gasket groove chamber an optimized flow channel is obtained for the underflowing heat exchanging medium and correspond¬ ing small pressure losses. Additionally, by obviating the gasket groove chamber smaller shaping ratios are made possible and thereby a better embossability in the produc¬ tion of heat exchanger plates, thus reducing the cracking risk in the metal shaping. The uninterrupted corrugations to the edge of the heat exchanger plate render the heat exchanger plate suitable for use in a soldered plate heat exchanger. Thus, the same plates may be used in both a plate heat exchanger of the clamping frame type and of the soldered type reducing the overall production costs. Using a heat exchanger plate in a vulcanization press as a press mould means that the gasket is vulcanized directly on the heat exchanger plate resulting in a firm adhesion of the gasket to the heat exchanger plate. In further embodiments of the invention the radial cor¬ rugation extending from the entry and exit openings inter¬ sects the gasket at an angle of 50 to 80°, preferably of 70°. With this angle of intersection, the position of the cross- ing points of the corrugation are determined, on one hand, and the flow passage between the heat exchanger plates in this region is defined in a flow promoting way, on the other hand. Thereby, the corrugation of the heat exchanger plates forming a flow passage in the preferred embodiment (70°) is arranged only at approximately 20° to the flow from the entry and exit openings to the heat exchanger surfaces, so that the corresponding low pressure losses are obtained. The present invention will be described hereinafter with reference to an embodiment and with reference to the acco - panying drawings, in which: 17 . rrπ *e> . . σ n i σo Pl' T'i <-* ~ r- C-T.T r-* -P "^ hC - ;; ' - ' > ~ according to the prior art, Figure 2 is a plan view of a heat exchanger plate in accordance with the first aspect of the invention, only the top portion of the plate being illustrated, Figure 3 is a detail view of the region III of Figure 2, with three individual exposed, superimposed heat exchange plates and the associated gasket, Figure 4 is a cross-section view corresponding to the view line IV of Fig. 3, Figure 5 is a perspective view of a gasket adapted to the corrugation. Figure 6 is a plan view of a heat exchanger plate in accordance with the second aspect of the invention, Figure 7 is a detail view of the framed region VII of Figure 6, Figure 8A is a detail view of a heat exchanger plate of Figure 6 and the associated gasket, Figures 8B and 8C are enlarged detail views of the encircled areas of Figure 8A. Figure 9 is a perspective view of a heat exchanger plate and a cutaway portion of a top press mould of a vulcaniza¬ tion press in accordance with the third aspect of the inven¬ tion, and Figure 10 is a perspective view similar to Figure 9 additionally showing a lower press mould of the vulcaniza¬ tion press. In the heat exchanger shown in Figure 1, for the sake of better overview, only two plates 1, 2 are shown. The clamp- ing plates 4, 14 between which the plate pack is compressed, are not yet tightened by the tightening screws 5 in the open condition shown. The further parts of the heat exchanger frame are not particular or do not have a bearing on the invention, respectively. In the illustration of Figure 2, enlarged with respect to Figure 1, of a portion of a heat exchanger plate, the entry and exit openings, respectively, of the heat exchang¬ ing medium are designated by 8 and 9. From these openings 8, 9, corrugations extend radially or in a fan-like way, in the embodiment shown, radially and rotated about 20°, to heat c> rif t h C_r .™-l cπ hills of this profile being designated by 11. Between the corrugation hills the correspondingly formed corrugation troughs are extending. The heat exchanger plate according to Figure 2 is shown without a gasket in position, the extent of the gasket 10 being plotted by dotted lines in the region of the opening 9, as an inserted gasket 15 would be positioned (see Figures 3, 4, 5) . From this figure it is clearly shown that, in the outlet region of the entry and exit openings 8, 9, a gasket groove is completely eliminated and that the profile is con¬ tinuous over the extent of the gasket 10. At the circumfer¬ ence of the heat exchanger plate, a gasket groove 6 is pro¬ vided as is conventional, accommodating the peripheral gasket. However, according to the second aspect of the invention, also the peripheral gasket groove is eliminated, as is discussed below. In the detail view of Figure 3 a top heat exchanger plate 3 and underlying heat exchanger plates 2 and 1 are illustrated, in which the underlying heat exchanger plates are exposed. Between the bottom heat exchanger plate 1 and the intermediate heat exchanger plate 2 the gasket 15 is inserted, while no gasket is provided between the top and intermediate heat exchanger plates. This gap or channel car- ries flow, the optimal flow conditions being obtained because of the missing gasket groove. As is clearly seen in Figure 3, crossing points 12 are obtained between the corrugation hills 11 of the lower heat exchanger plate 1 and the corrugation troughs of the inter- mediate heat exchanger plate 2, the crossing points flanking the gasket 15 on both sides. Only the hills or ridges of the corrugations are shown. Also, such crossing points 13 are obtained between the corrugation hills 11 of the inter¬ mediate heat exchanger plate 2 and the corrugation troughs of the top heat exchanger plate 3. Because of the uninter¬ rupted extent of the profiles between the support points 12 and 13, respectively, the desired stiffness is obtained to apply the gasket pressure on the gasket 15. The configuration of the gasket 15, over the extent 10 of the gasket, is adapted to the cross-section obtained ^t ^^ri t- rs/s htsa p γ rV|aτι or n l a t- oc -"-_. i di C e C .Z]ZZZ 15 has corrugation hills 16 and interposed corrugation troughs, the corrugation hills 16 of the upper surface of the gasket crossing the corrugation troughs of the underside of the gasket . This is best shown in Figures 4 and 5. Thereby, the gasket cross-section is arranged so that sub¬ stantially the same gasket pressure exists in a plate pack compressed between the clamping plates 4, 14 of the plate heat exchanger. Figure 6 illustrates a second embodiment of the present invention wherein the corrugations 17 of the heat exchanger surfaces 7 extend uninterrupted to the edge 18 of the heat exchanger plate. Only some of the corrugations are shown in the figure while it is understood that the whole heat exchanger plate is covered by corrugations. The corrugations may be of the same shape as in the previous figures. The invention is equally applicable to any shape of the corruga¬ tions . Figure 7 is a detail view of the framed region VII of Figure 6. As is shown in Figure 7, the edge 18 of the heat exchanger plate is provided with a flange 21. In a plate heat exchanger of the clamping plate type as is shown in Figure 1, the flange has no significant function but adds to the stability and integrity of the plate heat exchanger. However, in a plate heat exchanger of the soldered type, that is the heat exchanger plates are soldered together without the need of any gasket, the flange 21 is used to provide a further surface for the soldering in addition to the soldering at the crossing points between the heat exchanger surfaces. Figure 8A is a detail view of a heat exchanger plate with the associated gasket 15, 19 placed on the heat exchanger plate 2. As is shown in Figures 8B and 8C similar to Figure 3, the gasket is positioned between an intermediate plate (the broken lines depcting the hills) and a top plate (the solid lines depicting the troughs) . In the region shown in Figure 8C, the peripheral gasket 19 has a cross section corresponding to that shown in Figure 4, but with parallel corrugations. The corrugation of the heat exchanger surfaces (7) may intersect the peripheral gasket (19) at an angle in the range of approximately 40° to.70°. A small intersection angle results in a small pressure drop but lower efficiency of the heat exchanger, while a greater intersection angle results in a large pressure drop but greater efficiency of the heat exchanger. Thus, the angle is selected in accordance with the application of the heat exchanger. It is preferred that the gasket is vulcanized in order to obtain the desired strength. In accordance with the third aspect of the present invention, the vulcanization is effected by means of a vulcanization press using the heat exchanger plate itself as one of the press moulds. This results in that the gasket is adhered firmly to the heat exchanger plate through the vulcanization process. In Figure 9, a portion of a top press mould 23 is shown together with a heat exchanger plate 22. For the sake of better clarity in the drawings, the gasket and the rest of the vulcanization press are omitted. For the same reason, the corrugations around the exit and entry openings are sim- plified, while it is understood that any form of corruga¬ tions may be used. It will be appreciated by persons skilled in the art that the gasket is placed between the press mould 23 and the heat exchanger plate 22 which are then compressed and subjected to a conventional vulcanization treatment. In Figure 10 a further advantageous development is shown. In this embodiment, the vulcanization press comprises two press moulds 23 belonging to the vulcanization press proper and one heat exchanger plate 22. Thus, two gaskets are placed over and under, respectively, the heat exchanger plate 22 and are vulcanized at the same time. As is known, every second plate in a plate heat exchanger is provided with a gasket on both sides, while the other plates have no gaskets. The adhesion of the gasket to the heat exchanger plate may be enhanced even further by providing perforations over the extent of the gasket, that is holes are provided in the plates with a suitable spacing. In Figure 8C, two holes 20 are shown. Thus, when two gaskets are vulcanized in a vul¬ canization press as shown in Figure 10 at the same time, they are bonded together through the perforations 20 result¬ ing in a very stronq bindinq of the σaskets toσether and to the heat exchanger plate. SUBSTITUTΈ SHEET (RULE 26)

Claims: CLAIMS 1. A plate heat exchanger comprising heat exchanger plates arranged adjacent each other into a compressed pack, the heat exchanger plates forming closed channels for alter- nately a heat emitting and a heat absorbing medium by means of peripheral gaskets arranged between the plates, the chan¬ nels being able to be charged with the respective medium via entry and exit openings aligned with each other, wherein corrugations extend from the entry and exit openings and gaskets are arranged in this corrugation region, alternately f rnm oτ-ιo rip . r- of n] a f βq +- o f- rτ-» nαyr f o <"•<-> .• -. ■ »-— 4- ■! -» -- *- 1 entry and exit openings, respectively, from the heat ex¬ changer surfaces, characterized in that the corrugations extending from the entry and exit openings (8, 9) extend in a substantially radial direction to the heat exchanger sur¬ faces (7) and, hence, uninterrupted traverses the region of the gasket extent (10) and cross the corresponding corruga¬ tion of the adjacent heat exchanger plates (1, 2), such that the extent (10) of the gasket is flanked on both sides by the crossing points (12) of the corrugation hills (11) of one plate (1) with the corrugation troughs of the other plate (2) , the gasket (15) arranged between the heat exchanger plates (1, 2) varying in cross-section to be adapted to the profile of the heat exchanger plates (1, 2) in this region, such that substantially the same specific gasket pressure is obtained over the whole extent (10) of the gasket in a compressed condition. 2. A plate heat exchanger according to Claim 1, charac¬ terized in that the corrugation extending in a substantially radial direction from the entry and exit openings (8, 9) intersect the gasket (15) at an angle of 50 to 80°, preferably 70°. 3. A plate heat exchanger according to Claim 1, charac¬ terized in that the corrugations (17) of the heat exchanger surfaces (7) extend uninterrupted to the edge (18) of the heat exchanger plates (1, 2) , the peripheral gasket being arranged between the heat exchanger surfaces, such that the extent of the peripheral gasket is flanked on both sides by the crossing points of the corrugation hills of one plate with the corrugation troughs of the other plate, the peri- pheral gasket (19) arranged between the heat exchanger plates varying in cross-section to be adapted to the profile of the heat exchanger surfaces (7) in this region. 4. A plate heat exchanger according to Claim 3, charac- terized in that the corrugation of the heat exchanger sur¬ faces (7) intersect the peripheral gasket (19) at an angle in the range of approximately 40° to 70°. 5. A plate heat exchanger according to Claim 4, charac¬ terized in that the gasket (15, 19) is vulcanized in situ. 6. A plate heat exchanger according to Claim 5, charac¬ terized in that the hest pγrb-ιηror .-..-.ho τ_c; r^ f a e (20) over the extent of the peripheral gasket (19) and in that two peripheral gaskets are vulcanized together through the perforations (20) . 7. A plate heat exchanger according to one of the previ¬ ous claims, characterized in that the heat exchanger plates are flanged (21) to be able to be used in a soldered plate heat exchanger. 8. A method of producing a plate heat exchanger accord- ing to one of the previous claims, characterized in that the gasket is vulcanized in a vulcanization press (23) using a heat exchanger plate (22) as a press mould. 9. A method according to claim 8, characterized in that two gaskets are vulcanized in a vulcanization press using a heat exchanger plate as an intermediate press mould (22) between the two gaskets and two press moulds (23) of the vulcanization press. 10. A method according to claim 9, characterized in that the heat exchanger plate is perforated (20) over the extent of the peripheral gasket.

Inventors: PERSSON LARS, PERSSON, LARS
Applicants: PERSSON LARS, TAU ENERGY PRODUCTS AB, PERSSON, LARS
Application year: 1996
Main classification: F28F3
IPC codes: F28D9, F28F3