WO2009082336A1

WO2009082336A1 - Plate heat exchanger with guiding arrangement at the short ends

Info

Publication number: WO2009082336A1
Application number: PCT/SE2008/051387
Authority: WO
Inventors: Kristian Walter; Lars Svensson
Original assignee: Alfa Laval Corporate Ab
Priority date: 2007-12-21
Filing date: 2008-12-02
Publication date: 2009-07-02
Also published as: SE0702864L; SE531856C2

Abstract

The invention relates to a plate heat exchanger (1) including at least one gasket (3) and a package of heat exchanger plates (4) which are provided with inlet and outlet ports (5, 6, 7, 8) which ports constitute channels through the package and between the heat exchanger plates (4), wherein the heat exchanger plates (4) are permanently joined in pairs to constitute cassettes (2), and where the gasket (3) is disposed between the cassettes (2) in a groove (12) in the heat exchanger plates (4) and delimits in combination with the cassettes (2) in every second space between plates a first flow passage for a first fluid, and the cassettes (2) delimit a second flow passage for a second fluid, where the heat exchanger plate (4) is provided guiding arrangements (20) for guiding the heat exchanger plates (4) of each cassette (2) in relation to each other.

Description

Plate heat exchanger with guiding arrangement at the short ends

FIELD OF THE INVENTION

The present invention relates to a plate heat exchanger, and more specifically to a supporting and guidance arrangement of the heat exchanger plates of a plate heat exchanger. The heat exchanger plates are permanently joined in pairs to constitute cassettes, and a gasket is disposed between the cassettes in a groove in the heat exchanger plates and delimits in combination with the cassettes, in every second space between plates, a first flow passage for a first fluid, and the cassettes delimit a second flow passage for a second fluid.

BACKGROUND OF THE INVENTION

Food manufacture or food processing industry is typically characterized by the need to process and treat highly viscous products, e.g. concentrates for carbonated beverages, juices, soups, dairy products and other products of fluid consistency. For natural reasons, the hygiene aspirations and expectations in this context are extremely high to enable the requirements of various authorities to be met.

Plate heat exchangers are used in the food industry for a number of different purposes. Problems with regard to so-called dead zones, the accumulation of fibers and other solid material which may be contained in products, and the possibility of flexible and effective cleaning, are extremely important factors in this context. The design of plate heat exchangers therefore plays a crucial part in making it possible for effective heat transfer and hygiene to be achieved while at the same time preventing so-called dead zones in which products may be caught and hence become fertile ground for bacteria growth. In this context it is advantageous to use so-called semi-welded plate heat exchangers, i.e. heat exchangers comprising a number of cassettes formed by welding heat exchanger plates together in pairs. The weld seam normally runs along the side edges of the cassettes and around the portholes. A gasket is disposed between the respective cassettes and is normally made of a rubber material and situated in a groove of the heat exchanger plate. One fluid flows inside the cassettes, and another fluid between the cassettes. Semi-welded plate heat exchangers tolerate relatively high pressures and make it possible to open the plate package and clean the spaces between pairs of welded heat exchanger plates. The welds which replace the gaskets in every second space between plates round the heat exchange surface of the heat exchanger plates reduce the need for gasket replacement and enhance safety.

The material and configuration of the heat exchanger plates, the design of the heat transfer surfaces with regard to pattern and press depth, etc., are important factors in hygienic applications.

To make safe that the two heat exchanger plates are aligned in relation to each other before welding, the two heat exchanger plates are provided arrangements that forces the two heat exchanger plates into alignment in relation to each other. Such arrangement is disclosed in EP-B1 -0 830 556, where a plate heat exchanger comprises stacked heat exchanger plates with depressed corner areas in diagonally opposed corners of each heat exchanger plate. Another arrangement to align heat exchanger plates in relation to each other is disclosed in US-A-5 056 590, where a traditional plate heat exchanger is shown, having a collar-shaped arrangement in center portion of each of the two short sides. The collar-shaped alignment arrangement is inwardly tapered so that an adjacent heat exchanger plate with similar arrangement is guided into alignment with the first heat exchanger plate.

To simplify the manufacture and to make cheaper to manufacture the above- mentioned cassettes, welding have been replaced by brazing. In order to distribute the solder on a first heat exchanger plate of the cassette and to align the second heat exchanger plate in relation of the first heat exchanger plate guidance is needed to achieve a high-quality product. None of the above shown solutions give an accurate enough alignment.

SUMMARY OF THE INVENTION

The object of the invention is to achieve very accurate alignment of the two heat exchanger plates of a cassette and to provide an improved solution for the alignment of the two heat exchanger plates of a semi-brazed heat exchanger plate. This object is achieved according to the invention by a heat exchanger plate that is provided guiding arrangements for guiding the heat exchanger plates of each cassette in relation to each other.

According to a first aspect of the invention the guiding arrangements are provided at each short end of the heat exchanger plates.

According to a further aspect of the invention the guiding arrangements are formed as recesses formed to partially receive a carrying bar.

According to a further aspect of the invention the recess is symmetrically formed relative to a centre line of the heat exchanger plate. According to a further aspect of the invention the recess extends towards the long sides and the opposite short side, and where the recess is a through-recess relative to the thickness of the heat exchanger plate.

According to a further aspect of the invention the recess includes an edge portion that extends substantially perpendicular from the main extension plane of the heat exchanger plate.

According to a further aspect of the invention the edge portions of the heat exchanger plate extend in substantially opposite directions at the two short ends of the heat exchanger plate.

According to a further aspect of the invention the edge portion at a first end of the heat exchanger plate extends in a substantially opposite direction from the main extension plane compared to the edge portion at a second end of the heat exchanger plate.

A further object of the invention is to provide a plate heat exchanger with heat exchanger plates of the above-mentioned type formed into cassettes. This object is achieved according to the invention in that the two heat exchanger plates forming the cassette are arranged so that one of corresponding extension surfaces of each heat exchanger plate faces each other.

This object is further achieved according to the invention in that the guiding arrangements in a first end of the two heat exchanger plates extends in a substantially common direction relative to the main extension plane, and where the guiding arrangements in a second end of the two heat exchanger plates extends in a substantially common direction relative to the main extension plane, the extension direction of the guiding arrangements in the second end of the two heat exchanger plates being substantially opposite to the extension direction of the guiding arrangements in the first end of the two heat exchanger plates.

Further aspects of the invention are defined in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be explained more with reference to the accompanying drawings, where:

Fig. 1 discloses schematically a perspective view of a plate heat exchanger according to the invention; Fig. 2 discloses schematically a partial detailed perspective view of the plate heat exchanger of Fig. 1 ;

Fig. 3 discloses schematically a perspective view of two heat exchanger plates according to the invention;

Fig. 4a discloses schematically a front view of a heat exchanger plate according to the invention;

Fig. 4b discloses schematically a detailed front view of areas A and B of the heat exchanger plate of Fig. 4a;

Fig. 5a discloses schematically a front view of a heat exchanger plate according to the invention; Fig. 5b discloses schematically a detailed front view of areas C and D of the heat exchanger plate of Fig. 5a;

Fig. 6 discloses a cross-sectional view of along the lines A-A and B-B of the detailed areas A and B of Fig. 4a;

Fig. 7 discloses a cross-sectional view of along the lines C-C and D-D of the detailed areas C and D of Fig. 5a; and

Fig. 8 discloses a cross-sectional view of an alternative embodiment according to the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Figs. 1 -8 disclose different views of a plate heat exchanger according to the invention. Figs. 1 and 2 shows a plate heat exchanger 1 including a number of cassettes 2 and gaskets 3, where a gasket 3 is arranged in the space between two adjacently arranged cassettes 2. Each cassette 2 comprises two heat exchanger plates 4 permanently joined together. The heat exchanger plates 4 have at least four ports or portholes constituting 5, 6, 7, 8 inlet and outlet ports and a heat transfer surface 9 with ridges and valleys 10. The cassette 2 may be made by gluing, welding, brazing or any other suitable joining method, whereby the two heat exchanger plates 4 are joined together permanently along their periphery and around at least two of ports 5, 6, 7, 8. In most cases the heat exchanger plates 4 are not joined at the absolute peripheral of the plates, but along a gasket recess of the heat exchanger plate 4 and along a diagonal recess of the heat exchanger plate 4.

The plate heat exchanger 1 further comprises two end plates 50, 30 where- in-between the cassettes 2 are arranged hanging on a carrying bar 40 that extends between the two end plates 50, 30. By pushing the end plate 30, which is movable in relation to the carrying bar 40, the cassettes 2 are pressed together to form a plate package. The end plate 50 is suitably provided with a number of port or connections 25, 26, 27, 28 corresponding to the port 5, 6, 7, 8 of the heat exchanger plate 4. The end plate 30 may also be provided with ports, as well as the port 25, 26, 27, 28 may be provided with a blind cover. The carrying bar 40 is in one end fixedly attached to an upper end of the end plate 50 and in the opposite end fixedly attached to an upper end of a support column 70. A guide bar 60 connects a lower end of the support column 70 with a lower end of the end plate 50.

It is to be noted that the heat exchanger plate 4 may include another number of port channels than the four ports disclosed in the shown embodiments. The end plates 50, 30 will typically have a corresponding number of ports. The heat exchanger plates 4 are configured in such a way that as few contact points as possible occur between two mutually adjacent cassettes 2 prevents fibers and solid materials which may be contained in the fluid being caught in the space between the cassettes 2. The heat exchanger plates 4 are designed so that contact points for necessary mechanical support occur largely only on the inside, between two heat exchanger plates 4 which are to be joined together to form the cassette 2, by opposite ridges abutting against one another. In contrast, at portholes 6 and 8 the heat exchanger plates 4 abut completely against one another and are joined together permanently so as to form a seal against the fluid which is intended to flow through the portholes. Portholes 5 and 7, which constitute the inlet and outlet to the cassettes 2, are provided instead with nibs that are necessary for providing necessary mechanical support at the porthole. The gasket 3, which is preferably made of an elastic material, e.g. rubber material, is disposed in a groove 9 (see Fig. 3, 4a or 5a) which extends along the periphery of the constituent heat exchanger plates 4 of the cassette and around ports 6 and 8. There is a ring gasket 3a round ports 5 and 7. The purpose of the gaskets 3 and 3a is to seal the space between two cassettes 2, and it has in the area around ports 6 and 8, along its side facing the porthole, a circumferential protruding bead. The gasket may possibly comprise a metal or be surrounded by a second material, e.g. metal, PTFE, etc.

The heat exchanger plate 4 includes as discussed above in a manner known per se a corrugation or pattern 10 for increasing the heat transfer and four port holes 5, 6, 7, 8 for forming a corresponding number of port channels extending through the plate package and being in connection with the flow channels formed between the heat exchanger plates 4.

At each short end of the heat exchanger plate 4 guiding arrangements 20 are provided, best seen in Figs. 4a-b and 5a-b. The guiding arrangements 20 are formed as a cut-in portion or recess 21 extending symmetrically from a center line (A-A, B-B, C-C, D-D) of the short end 1 1 respectively 14 of the heat exchanger plate 4 and towards the two long sides 12, 13 of the heat exchanger plate 4. The recess 21 also extends toward the other short end 14 respectively 1 1 of the heat exchanger plate 4. The recess 21 of the heat exchanger plate 4 is formed to receive a carrying bar 40 of the plate heat exchanger 1 , whereon the heat exchanger plates 4, i.e. the cassettes 2 formed by two adjacently arranged heat exchanger plate 4, are mounted to form the plate heat exchanger 1. The carrying bar 40 is typically I-shaped and the heat exchanger plates 4 or more precisely the cassettes 2 formed by the pair of heat exchanger plates 4 are to be hung onto the carrying bar 40. Fig. 6 shows a cross-sectional view of the guiding arrangements 20 along the line A-A and the line B-B of Fig. 4b that an edge portion 22 around the recess 21 deviates from a main extension plane Y (see Fig. 3) of the heat exchanger plate 4. Closest to the recess 21 a portion 23 of the edge portion 22 is substantially perpendicular to the main extension plane Y of the heat exchanger plate 4.

As seen in Fig. 6 the edge portion 22 of the guiding arrangements 20 on the heat exchanger plate 4 extend differently at the two short sides 1 1 and 14 of the heat exchanger plate 4. In one (the upper) short end 11 of the heat exchanger plate 4 the guiding arrangement 20, more precisely the edge portion 22 of the guiding arrangement 20, is directed or extending to the left, whereas the edge portion 22 of the guiding arrangement 20, is directed or extending to the right at the other (the lower) short end 14 of the heat exchanger plate 4. By having the edge portions 22 of the guiding arrangements 20 extending in opposite directions the pairing and orientating of two heat exchanger plates 4 to form a cassette 2 are facilitated.

In Fig. 3 is shown how two similarly shaped heat exchanger plates 4, 41 forms the cassette 2, where one heat exchanger plate 41 is rotated 180 degrees around an axis Z of the heat exchanger plate 4 so that corresponding corrugated surface of the two heat exchanger plates 4, 41 faces each other. The axis Z is parallel with the short ends 1 1 , 14 of the heat exchanger plate 4, 41 and located in the middle of the heat exchanger plate 4, 41. As the heat exchanger plates 4, 41 are pressed or arranged together before they are permanently joined, the guiding arrangements 20 of the two heat exchanger plates 4, 41 interacts (see Fig. 7) to that the two heat exchanger plates 4, 41 are correctly aligned in relation to each other. Thereby a correct position before joining of the two heat exchanger plates 4, 41 is achieved.

In Figs. 5a-b and 7 two heat exchanger plate 4 are paired to form a cassette 2. To facilitate the understanding that two heat exchanger plate 4 are paired into a cassette in Fig. 5a the corrugated pattern 10 of both heat exchanger plate 4 in the cassette 2 are shown, even though only heat transfer surface 10 of the top heat exchanger plate 4 would be visible in reality.

As shown in Fig. 7 the guiding arrangements 20 in a first end 15 of the two heat exchanger plates forming the cassette 2 extends in a substantially common direction relative to the main extension plane Y. The guiding arrangements 20 in the other and second end 16 of the two heat exchanger plates 4 also extends in a substantially common direction relative to the main extension plane Y. The extension direction of the guiding arrangements 20 in the second end 16 of the two heat exchanger plates 4 is substantially opposite to the extension direction of the guiding arrangements 20 of the first end 15 of the two heat exchanger plates 4.

The guiding arrangement 20 of the invention having an edge portion 22 and which extends substantially perpendicular from the main extension plane Y of the heat exchanger plate 4 also serves as a reinforcement of the recess 21 that also is used to hang the heat exchanger plates 4 onto a carrying bar 40. Normally a separate reinforcement plate needs to be attached on the heat exchanger plate 4 surrounding the recess 21 to provide needed strength of the recess or guiding arrangement 20.

When the cassettes 2 are hung onto the carrying bar 40 by using the guiding arrangement 20 of the upper end of the cassette 2, the guiding arrangement 20 of the lower end of the cassette 2 receives the guiding bar 60 so that the cassettes 2 are aligned in relation to each other and to facilitate the assembling of the plate heat exchanger 1.

In Fig. 8 a larger partial cross section of the cassette 2 is shown, where the space 19 formed between the heat exchanger plates 4 is apparent.

Although it is has not been mentioned it obvious for a person skilled in the art that the guiding arrangements can be used other purposes than for guiding the heat exchanger plates of each cassette in relation to each other, such as guiding the heat exchanger plates on the carrying bar etc.

The invention is not limited to the embodiments described above and shown on the drawings, but can be supplemented and modified in any manner within the scope of the invention as defined by the enclosed claims.

Claims

1 . A heat exchanger plate (4) which forms part of a package of heat exchanger plates for a plate heat exchanger (1 ), which heat exchanger plate (4) is provided with inlet and outlet ports (5, 6, 7, 8) which constitute channels through the package and between the heat exchanger plates (4), whereby the heat exchanger plates (4) are permanently joined in pairs to constitute cassettes (2), a gasket (3) is disposed between the cassettes (2) in a groove (12) in the heat exchanger plates (4) and delimits in combination with the cassettes (2) in every second space between heat exchanger plates (4) a first flow passage for a first fluid, and the cassettes (2) delimit a second flow passage for a second fluid, the heat exchanger plate (4) being provided with guiding arrangements (20) for guiding the heat exchanger plates (4) of each cassette (2) in relation to each other c h a r a c t e r i z e d i n t h a t the guiding arrangements (20) are provided at each short end (11 , 14) of the heat exchanger plates (4), and where the guiding arrangements (20) extend in substantially opposite directions at the two short ends (1 1 , 14) of the heat exchanger plate (4).

2. A heat exchanger plate (4) according to claim 1 , wherein the guiding arrangements (20) are formed as recess (21 ) formed to partially receive a carrying bar (40).

3. A heat exchanger plate (4) according to claim 2, wherein the recess (21 ) is symmetrically formed relative to a centre line (A-A, B-B, C-C, D-D) of the heat exchanger plate (4).

4. A heat exchanger plate (4) according to anyone of claims 2 or 3, wherein the recess (21 ) extends towards the long sides (12, 13) and the opposite short side (1 1 , 14), and where the recess (21 ) is a through-recess relative to the thickness of the heat exchanger plate (4).

5. A heat exchanger plate (4) according to anyone of claims 2-4, wherein the recess (21 ) includes an edge portion (22) that extends substantially perpendicular from the main extension plane (Y) of the heat exchanger plate (4).

6. A heat exchanger plate (4) according to claim 5, wherein the edge portions

(22) of the heat exchanger plate (4) extend in substantially opposite directions at the two short ends (1 1 , 14) of the heat exchanger plate (4).

7. A heat exchanger plate (4) according to claims 5 or 6, wherein the edge portion (22) at a first end (1 1 ) of the heat exchanger plate (4) extends in a substantially opposite direction from the main extension plane (Y) compared to the edge portion (22) at a second end (14) of the heat exchanger plate (4).

8. A plate heat exchanger (1 ) including at least one gasket (3) and a package of heat exchanger plates (4) which are provided with inlet and outlet ports (5, 6, 7, 8) which ports constitute channels through the package and between the heat exchanger plates (4), wherein the heat exchanger plates (4) are permanently joined in pairs to constitute cassettes (2), and where the gasket (3) is disposed between the cassettes (2) in a groove (12) in the heat exchanger plates (4) and delimits in combination with the cassettes (2) in every second space between plates a first flow passage for a first fluid, and the cassettes (2) delimit a second flow passage for a second fluid, c h a r a c t e r i z e d i n t h a t the heat exchanger plate (4) is formed according to any of the claims 1 -7.

9. A plate heat exchanger (1 ) according to claim 8, wherein the two heat exchanger plates (4) forming the cassette (2) are arranged so that one of corresponding extension surfaces (10) of each heat exchanger plate (4) faces each other.

10. A plate heat exchanger (1 ) according to claim 9, wherein the guiding arrangements (20) in a first end (15) of the two heat exchanger plates (4) extends in a substantially common direction relative to the main extension plane (Y), and where the guiding arrangements (20) in a second end (16) of the two heat exchanger plates (4) extends in a substantially common direction relative to the main extension plane (Y), the extension direction of the guiding arrangements (20) in the second end (16) of the two heat exchanger plates (4) being substantially opposite to the extension direction of the guiding arrangements (20) in the first end (15) of the two heat exchanger plates (4).