AREA OF INVENTION

The present invention refers generally to plate heat exchangers allowing a heat transfer between two fluids at different temperatures for various purposes. Specifically, the invention relates to a plate heat exchanger having an end plate with improved means for fastening connections to the end plate.

BACKGROUND OF INVENTION

Plate heat exchangers are provided with or connected to pipes and pipe system for the communication and transporting of fluids back and forth to plate heat exchanger, fluids that are to be treated in the plate heat exchanger. The plate heat exchangers are provided with connection arrangements for connecting the pipes or pipe systems to the plate heat exchanger. The connection arrangements are often formed as a piece of pipe that extends from one end plate of the plate heat exchanger, where the extending part is supplied with a threaded portion which interacts with a corresponding threaded portion of the pipes or the pipe systems. The piece of pipe can be an integrated part of the end plate, by e.g. welding the piece to the end plate or by molding the end plates and piece of pipe in one process, but it is more common to have the piece of pipe or connection pipe as a separate part onto the end plate due a lower cost and more flexibility. Some essential requirements on the piece of pipe or connection pipe are that it should have a good sealing against the heat exchanger plates to avoid leakage, it should further a have axial locking to prevent the connection pipe to be pressed against the heat exchanger plates by external forces and potentially damage the heat exchanger plates or the gasket or sealing between the heat exchanger plate and connection pipe. Preferably it should a rotational locking to facilitate the mounting or interconnecting of pipes or pipe systems to the connection pipes.

In prior art numerous solutions for connection pipes are presented. In the prior art document GB 1 009 178 it is disclosed a plate heat exchanger, where a connection pipe is screwed directly into each connection port from the outside surface of the relevant end plate. Another solution is disclosed in EP- B1 -0 277 171 , where a plate heat exchanger is described having a lining which is screwed into the connection port and a connection sleeve abuts the end plate. In other solutions the connections are attached to the end plate by bolts that are fixedly attached to the end plate and where nut arrangements hold the connections to the end plate. It is also known to have a connection pipe with a flange that is inserted from the inside of the end plate and extending through the connection ports or outlets of the end plate and that is kept in place by the pressure from the heat exchanger plates when the heat exchanger plates or the plate package is squeezed together between the two end plates. This solution can be supplemented with a bushing or sleeve to firmly lock the connection pipe to the end plate. These prior art solutions fail to fulfill the above stated requirements of well-working connection pipe, since they only fulfill one or two of the requirements.

Due to further requirements of the customers the size of connection pipes and thereby also the connection ports or outlets are supplied in different size to cover every different customer requirements. It is expensive to have several different end plates and connection pipes to match all the different requirements. A general solution covering all requirements would be beneficial.

DISCLOSURE OF INVENTION

The object of the present invention is to provide a new design for plate heat exchangers which ensure that a connections pipe will not damage the heat exchanger plates. This object is obtainable by means of a plate heat exchanger design comprising a package of heat exchanger plates provided with inlet and outlet ports, the ports forming channels through the package for at least one heat exchange fluid, two end plates between which the plate package of heat exchanger plates is arranged, where at least said one end plate is provided with at least one through hole, which communicates with one of the channels, and where a connection pipe is arranged in the through hole of the at least one end plate, the connection pipe communicates with a pipe system transporting the at least one heat exchange fluid where the connection pipe extends through the through hole and being removably and radially and longitudinally lockable fastened to the at least one end plate. According to a further aspect of the invention the connection pipe is provided with a flange in the end facing the heat exchanger plates and abutting a surface of the end plate, the surface (14a) of the end plate facing the heat exchanger plates.

According to another aspect of the invention an adhesive means is provided between the surface of the end plate and the flange of the connection pipe, the adhesive means a double-stick tape, glue or the like.

According to yet another aspect of the invention the flange is provided with a lip on its outer periphery that extends from the surface of the flange directed towards the end plate and where the end plate is provided with a corresponding recess interacting with the lip of the flange.

According to still another aspect of the invention the connection pipe extends from the end plate and having an external thread, which is connected to a pipe of a pipe system, where the pipe is provided with an internal thread. The external thread of the connection extends over essentially the whole length of the connection pipe. The pipe abuts against an outside surface of the end plate.

According to another aspect of the invention a bushing having an internal thread is provided being in engagement with the external thread of the connection pipe, where the bushing abuts against an outside surface of the end plate. The bushing serves a transition piece having an external thread being in engagement with the internal thread of the pipe, where the internal thread of the pipe is larger than the external thread of the connection pipe.

Further aspects of the invention is apparent from the dependent claims and the description BRIEF DESCRIPTION OF THE DRAWINGS

Further objects, features and advantages will appear from the following detailed description of several embodiments of the invention with reference to the drawings, in which: Fig. 1 is a perspective view of a plate heat exchanger according to the present invention;

Fig. 2 is a perspective view of a plate heat exchanger according to the present invention;

Fig. 3 is detailed partial view A of the plate heat exchanger in Fig. 2 according to the present invention;

Fig. 4 is a perspective view of a connection pipe according to the present invention;

Fig. 5 is partial side view of an upper part of a plate heat exchanger according to the present invention; Fig. 6 is detailed partial view B of the plate heat exchanger of Fig. 5 according to the present invention; and

Fig. 7 is partial side view of an upper part of a plate heat exchanger according to the present invention having a pipe mounted onto the connection pipe; Fig. 8 is a perspective view of an alternative embodiment of the connection pipe according to the present invention;

Fig. 9 is a perspective view of a bushing according to the present invention; and

Fig. 10 is a partial perspective view of a connection pipe and an end plate according to the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS

Heat exchangers are used for transferring heat between two fluids separated by a solid body. Heat exchangers can be of several types, the most common are spiral heat exchangers, tubular heat exchangers and plate heat exchangers. Plate heat exchangers are used for transferring heat between a hot and a cold fluid that are flowing in alternate flow passages formed between a set of heat exchanger plates. The arrangement of heat exchanger plates defined above is enclosed between end plates that are relatively thicker than the heat exchanger plates. The inner surface of each end plate faces the heat exchanger plates. Figs. 1-2 disclose a plate heat exchanger 1 for treatment of a medium.

The plate heat exchanger 1 comprises a large number of compression-molded heat exchanger plates 2, which are provided in parallel to each other and successively in such a way that they form a plate package 3. The plate package 3 is provided between a first end plate 6, also called frame plate, and a second end plate 7, also called pressure plate. Between the heat exchanger plates 2, first plate interspaces and second plate interspaces are formed.

The first plate interspaces and the second plate interspaces are provided in an alternating order in the plate package 3 in such a way that substantially each first plate interspace is surrounded by two second plate interspaces, and substantially each second plate interspace is surrounded by two first plate interspaces. Different sections in the plate package 3 are delimited from each other by means of gaskets in each plate interspace. The gasket, which is preferably made of an elastic material, e.g. rubber material, is disposed in a groove which extends along the periphery of the constituent heat exchanger plates 2 and around ports. The gasket may possibly comprise a metal or be surrounded by a second material, e.g. metal, PTFE, etc.

As shown in Figs. 1-2, the plate package 3, i.e. the heat exchanger plates 2 and the gaskets (not shown) provided there between, is kept together between the end plates 6 and 7 by means of threaded tie bolts 30 in a manner known per se. The tie bolts 30 extends from the first end plate 6 and passing through holes or recesses in the edge portions of the second end plate 7. The heat exchanger plates 2 are arranged hanging on a carrying bar 31 that extends between the first end plate 6 and a support column 32, and/ or standing on a guide bar 33. The first end plate 6 is connected to the support column 32 by the carrying bar 31 , which in one end is fixedly attached to an upper end of the first end plate 6 and in the opposite end fixedly attached to an upper end of the support column 32. The second end plate 7, which is movable along the carrying bar 31 , is used to press the heat exchanger plates 2 together to form the plate package 3. The guide bar 33, that guides the heat exchanger plates 2 in their lower end, connects a lower portion of the support column with a lower part of the first end plate 6. The heat exchanger plate 2 discussed above includes in a manner known per se a corrugation or pattern for increasing the heat transfer and a number of port holes 4 for forming a corresponding number of port channels 5 extending through the plate package 3 and being in connection with the flow channels 5 formed between the heat exchanger plates 2. On the first end plate 6 is a number of through holes 8 (best shown in

Fig. 5 and 7), which corresponds to the inlet/ outlet port holes 4 of the heat exchanger plates 2. In the shown embodiment the end plate 6 is provided with four though holes 8, but it can be fewer or more through holes 8 depending on the design of the heat exchanger plates 2. It is also possible to arrange the through holes 8 on the second end plate 7 or that both end plates 6, 7 are provided with a number of through holes 8. In the through holes 8 are arranged connection pipes 9. In the shown embodiments the first end plate 6 is provided with through holes 8 and corresponding number of connecting pipes 9, two through holes 8 and corresponding number of connecting pipes 9 are arranged in the lower end of the end plate 6 and two through holes 8 and corresponding number of connecting pipes 9 are arranged in the upper end of the end plate 6. The connection 9, which principle design is shown in Fig. 4, serves as connection part interconnecting the plate heat exchanger 1 or more precisely the plate package 3 with associated pipes 12 or pipe system 10. The connection pipe 9 is formed as a cylindrical part 21 having a through hole 22. In one end of the cylindrical part 21 is provided a flange portion 17, which extends outwardly, substantially perpendicular to the longitudinal extension of the cylindrical part 21. In the end opposite to the end of the cylindrical part 21 , which is provided with a flange portion 17, an external thread 1 1 is formed. The external thread 1 1 may be formed along the entire length of the cylindrical part 21 , i.e. almost to the end of the cylindrical part 21 , which is provided with an annular flange portion 17, or the external thread 1 1 might only be formed along a portion of the cylindrical part 21. The associated pipe 12 or pipe system 10 is formed with a corresponding internal thread 13, which interacts with the external thread 1 1 to create a secure connection between the plate heat exchanger 1 and pipe 12 and/or pipe system 10. The connection pipe 9 is inserted in the through hole 8 of the end plate

6 from the inside of the end plate 6, where the inside surface is the surface 14a of the end plate 6 which faces the plate package 3, and is pushed through the through hole 8 until the flange 17 of the connection pipe 9 abuts the inside surface 14a of the end plate 6. The opposite end of the connection pipe 9 is now extending from the outside of the end plate, where the outside surface is the surface 14b of the end plate 6 which is turned or directed away from the plate package 3.

According to a first embodiment an adhesive means 16 (see Fig. 6) is provided between the flange 17 of the connection pipe 9 and the inside surface 14a of the end plate 6. The adhesive means 16 locks the connecting pipe 9 in relation to the end plate 6, both rotationally and axially. The adhesive means 16 can be a double-stick tape, a glue or similar. Preferably the adhesive 16 is arranged on the entire surface of the annular flange 17, but it can also be arranged on selective spots of the flange surface. According to a second embodiment a bushing or sleeve 15 is arranged or threaded on the external threaded portion 1 1 of the connection pipe 9 so that the bushing 15 abuts the outside surface 14b of the end plate 6. The bushing 15 locks the connection pipe 9 in relation to the end plate 6, at least axially. To further ensure that the connection pipe 9 is rotationally locked in relation to the end plate 6, the flange 17 can be provided with a lip 18 on the outer periphery of the flange 17. The Iip18 extends axially or is directed towards the end plate 6. The end plate 6 is provided with a corresponding recess 19, which interacts with the lip 18 of the flange 17 so that when the flange 17 abuts the inside surface 14a of the end plate 6 the lip 18 enters the recess 19, and the connection pipe 9 cannot be rotated in relation to the end plate 6. The lip 18 can be shaped as a small portion of the flange 17, which is bent up from the flange surface to form a small portion extending from the surface of the flange (see Fig. 10), directed towards the end plate 6, but is can also be shaped as a small pin, peg or similar that is mounted onto the periphery of the flange 17 and extending towards the end plate 6. Instead of using the lip 18 for locking rotationally, an adhesive means can be used for achieving the same. To be able to arrange that the bushing 15 abuts the end plate 6 implies that the connection pipe 9 is formed with an external thread 1 1 along the entire length of the connection pipe. This is shown in Fig. 8.

Customers use pipes 12 or pipe systems 10 having different pipe sizes. To be able to connect these pipes 12 or pipe systems 10 to the plate heat exchanger 1 it is possible have end plates with different through holes 8 sizes, but this is a rather expensive solution. Preferably is should be possible to connect one and the same plate heat exchanger 1 to the pipes 12 or pipe systems 10 having different pipe sizes. To achieve this a transition piece 24 (see Fig. 7) can be used having an internal diameter and thread 13 that corresponds to the external thread 1 1 of the connection pipe 9 and also having an external thread 25 adapted to the pipes 12 or pipe systems 10 to which its aimed to be connected.

The transition piece 24 can be configured so that is arranged on a portion of the external thread 1 1 of the connection pipe 9 (not shown), but it can also be shaped so that one end of the transition piece 24 can be arranged abutting the outside surface 14b of the end plate 6, thus locking the connection pipe 9 to the end plate 6. The transition piece 24 can accordingly be formed as piece pipe or cylinder as shown in Fig. 7 having an internal thread 13 at least along a portion of its length or having an internal thread 13 along its entire length. The external thread 25 is formed at least along a portion of the length of the transition piece 24. It can also be shaped as a bushing 15, see Fig. 9, having a hexagonal, octagonal or suitable edge head 23 in one end of the bushing 15 and having an external thread 20 along the external surface of the bushing 15. The bushing 15 of Fig. 9 provides a locking means for easy locking of the connection pipe 9 to the end plate 6 and a transition piece 15 or 24 for adapting the plate heat exchanger 1 to pipes 12 or pipe systems 10 of various size. In the above description and the drawings of the embodiment is has been described as if the connection pipe 9 is arranged on the first end plate 6, but it is obvious that the connection pipe 9 can also be arranged on the second end plate 7 or on both end plates 6, 7 simultaneously, all pending on the function and purpose of the plate heat exchanger 1.

In the above description the term connection pipe has been used for the part that extends through the end plate and which seals off against heat exchanger plates. In art the term lining has been used for corresponding parts, but where the focus is more the protecting function in relation to the end plate, and where the part substantially not extends from the end plate.

Further has the term bushing been used to the part that locks the connection pipe to the end plate. The term bushing includes also sleeves, quill, casing and penetration piece. Likewise does the term lip, which describes the small extending part of the flange periphery of the connection pipes, include pin, peg, tap, stud, tab lug, lap and head.

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.

REFERENCE SIGNS:

A: Detailed view of Fig. 2 30: Tightening bar

B: Detailed view of Fig. 5 31 : Carrying bar

1 : plate heat exchanger 32: Support column

2: heat exchanger plate 33: Guiding bar

3: plate package

4: inlet and outlet ports

5: channel

6: end plate

7: end plate

8: through hole

9: connection pipe

10: pipe system

1 1 : external thread

12: pipe

13: internal thread

14a: inside surface

14b: outside surface

15: bushing

16: adhesive means

17: flange

18: lip

19: recess

20: external thread

21 : cylindrical part

22: through hole

23: edge head

24: transition piece

25: external thread