EP2054679A1

EP2054679A1 - Plate heat exchanger and heat exchanger plant

Info

Publication number: EP2054679A1
Application number: EP07794183A
Authority: EP
Inventors: Rolf Ekelund; Claes Stenhede; Peter BJÖRNSSON
Original assignee: Alfa Laval Corporate AB
Current assignee: Alfa Laval Corporate AB
Priority date: 2006-08-23
Filing date: 2007-08-23
Publication date: 2009-05-06
Also published as: WO2008024066A1; CN101512252A; EP2054679A4

Abstract

The invention refers to a heat exchanger plant and a plate heat exchanger. The plate heat exchanger comprises a plate package (11) having heat exchanger plates provided beside each other for forming first plate interspaces for a first medium to be evaporated and second plate interspaces for a second medium in an alternating order in the plate package. Each heat exchanger plate comprises four portholes forming a first inlet port, which communicates with the first plate interspaces for supply of the first medium, a first outlet port, which communicates with the first plate interspaces for discharge of the first medium, a second inlet port, which communicates with the second plate interspaces for supply of the second medium, and a second outlet port, which communicates with the second plate interspaces for discharge of the second medium. The plate package comprises a drainage port (45), which communicates with the first plate interspaces and is closed in relation to the second plate interspaces. The drainage port permits discharge of a fluid collected in the first plate interspaces.

Description

Plate heat exchanger and heat exchanger plant

THE BACKGROUND OF THE INVENTION

The present invention refers to a plate heat exchanger according to the preamble of claim 1 , and a heat exchanger plant according to the preamble of claim 20.

Such a plate heat exchanger in the form of an evaporator and/or a condenser may form a part of a cooling medium circuit which also includes a compressor, a condenser, an expansion valve and an evaporator. The first medium is a cooling medium, for instance ammonium, which circulates through the components of the cooling medium circuit, and the second medium is a heat transfer medium, which may be any medium which can be cooled, for instance water, oil etc. During operation of such a plate heat exchanger with a cooling medium in which oil is not soluble, such as ammonium, oil is collected in the plate heat exchanger, and more precisely in the first plate interspaces. The oil mainly emanates from the lubrication of the compressor of the ammonium circuit. The collected oil deteriorates successively the performance of the plate heat exchanger, and after a longer time of use the collected quantity of oil becomes critical.

PRIOR ART

SU-964425 discloses a plate heat exchanger comprising a plate package with a plurality of heat exchanger plates which are provided beside each other in the plate package in such a way that a plate interspace is formed between each pair of adjoining heat exchanger plates. Every second such plate interspace forms a first plate interspace for a first medium and each of the remai- ning plate interspaces forms a second plate interspace for a second medium in such a way that the first plate interspaces and the second plate interspaces are provided in an alternating order in the plate package. The heat exchanger plates are in an operating position parallel with an horizontal plane. Every second heat exchanger plate comprises a number of depressions for collecting condensate. The condensate may be conveyed out from the plate package via vertical drainage pipes extending between the depressions and communicating with a horizontal collecting pipe outside the plate package.

SE-C-525 022 discloses a plate heat exchanger which is adapted to operate in an operating position as evaporator and condenser for a medium in a cooling medium circuit and which comprises a plate package having a plurality of heat exchanger plates provided beside each other in the plate package in such a way that plate interspaces are formed between the heat exchanger plates. The plate heat exchanger disclosed has a complicated construction and is intended for heat exchange between three different media. Barriers are provided in the plate interspaces for creating several chambers in each plate interspace for different media. The plate heat exchanger comprises a drainage port which communicates with an evaporating chamber. The drainage port is provided to permit discharge of a part quantity of the medium which is not evaporated. The discharged liquid quantity may then be recirculated to the plate heat ex- changer via the inlet.

SUMMARY OF THE INVENTION

The object of the invention is to provide an improved plate heat exchanger, especially an evaporator and/or a condenser for a cooling medium circuit comprising ammonium. A further object of the invention is to remedy the problem of collection of inpuri- ties, especially oil, in a plate heat exchanger in the form of an evaporator and/or a condenser. This object is acheived by the plate heat exchanger initially defined, which is characterized in that the plate package comprises a drainage port, which extends through the plate package and communicates with the first plate interspaces and is closed in relation to the second plate interspaces, wherein the drainage port is provided to permit in an operating position discharge of a fluid collected in the first plate interspaces.

By means of such a drainage port, the fluid, for instance oil, which is collected in the first plate interspaces may in an efficient manner be discharged therefrom. The drainage port permits continuous discharge of this fluid from the first plate interspaces so that the fluid level in the first plate interspaces may be kept at a low level, which securely will not be exceeded.

According to an embodiment of the invention, the drainage port is in the operating position located at a lower part of the plate heat exchanger. Advantageously, the drainage port is in the operating position located beneath the first inlet port. In such a way, it can be ensured that the fluid collected in the first plate interspaces will not accompanying the first medium which flows in through the first inlet port.

According to another embodiment of the invention, the drainage port is in the operating position located at a lower part of the plate heat exchanger. Advantageously, the drainage port is in the operating position located beneath the first outlet port. In such a way it may be ensured that the fluid collected in the first plate interspaces will not accompanying the first medium flowing out through the first outlet port.

According to a further embodiment of the invention, each heat exchanger plate comprises at least one further porthole, wherein the further portholes form the drainage port through the plate package. Consequently, a further smaller porthole is made in each heat exchanger plate, for instance in connection with the production of the portholes. In connection with the mounting of the plate package it is common to rotate every second heat exchanger plate 180° in its own extension plane. This means that the further porthole of every second heat exchanger plate, in connection with the production of the further porthole, will be located at one of the ends, and at the other end of the remaining heat exchanger plates.

According to a further embodiment of the invention, the plate package comprises a degassing port, which extends through the plate package and communicates with the second plate interspaces and is closed in relation to the first plate interspaces, wherein the degassing port is provided to permit discharge of a gas collected in the second plate interspaces. By means of such a degassing port, gas or air, which is present in the second medium and which is collected in an upper part of the second plate interspaces, may in an easy and efficient manner be removed. This is particularly advantageous in connection with the starting of the operation when such collections of gas can arise.

According to a further embodiment of the invention, the plate package comprises a degassing port, which extends through the plate package and communicates with the first plate interspaces and is closed in relation to the second plate interspaces, where- in the degassing port is provided to permit discharge of a gas collected in the first plate interspaces. By means of such a degassing port, gas or air, present in the first medium and collected in an upper part of the first plate interspaces, may in an easy and efficient manner be removed.

According to a further embodiment of the invention, each heat exchanger plate comprises two further portholes, wherein the further portholes form a drainage port and the degassing port through the plate package. These two further portholes may in an advantageous manner be provided at a respective end edge area of each heat exchanger plate in order to form the drainage port and the degassing port during the mounting of the plate package.

According to a further embodiment of the invention, the degas- sing port is in the operating position located at an upper part of the plate heat exchanger. Especially, the degassing port may in the operating position be located at the level of or above the second inlet port.

According to a further embodiment of the invention, each heat exchanger plate has a first end edge area and a second end edge area, and a first side edge area and a second side edge area. Advantageously each or substantially each plate interspace may extend between the first side edge area and the second side edge area of an adjoining heat exchanger plate. In such a way, the whole first plate interspace may be used for receiving and conveying the first medium to be evaporated in heat transfer contact with the whole or substantially the whole adjoining heat exchanger plates.

According to a further embodiment of the invention, the first inlet port is in the operating position located beneath the first outlet port. Furthermore, the first inlet port may be located at a lower end of the plate package with regard to the operating position. Advantageously, the plate heat exchanger may comprise a guide member in the inlet port, which is arranged to guide the first medium towards the lower end of the plate package.

According to a further embodiment of the invention, the first inlet port is in the operating position located above the first outlet port. Furthermore, the first inlet port may be located at an upper end of the plate package with respect to the operating position.

Advantageously, the plate heat exchanger may comprise a guide member in the inlet port, which is arranged to guide the first medium towards the lower end of the plate package. According to a further embodiment of the invention, the plate heat exchanger is adapted to operate as an evaporator in the operating position, wherein the first plate interspaces are arranged to permit evaporation of the first medium.

According to a further embodiment of the invention, the plate heat exchanger is adapted to operate as a condenser in the operating position, wherein the first plate interspaces are arranged to permit condensation of the first medium.

The object is also acheived by means of the heat exchanger plant initially defined, which is characterized in that the plate package comprises a drainage port, which extends through the plate package and communicates with the first plate interspaces and is closed in . relation to the second plate interspaces, wherein the drainage port is provided to permit in an operating position discharge of fluid collected in the first plate interspaces. Advantageously, the drainage port may, for instance via suitable members such a filter, be connected to the compressor for sui- table recirculation of the collected fluid.

According to a further embodiment of the invention, the plate heat exchanger forms an evaporator, wherein the heat exchanger plant also comprises a condenser and an expansion member, and wherein the plate heat exchanger, the compressor, the condenser and the expansion member form a closed cooling medium curcuit through which the first medium circulates. The plate heat exchanger may however also form a condenser, wherein the heat exchanger plant also comprises an evaporator and an expansion member, and wherein the plate heat exchanger, the compressor, the condenser and the expansion member form a closed cooling medium circuit through which the first medium circulates.

According to a further embodiment of the invention, the heat exchanger plant also comprises a condenser, and an expansion member, wherein the plate heat exchanger, the compressor, the condenser and the expansion member form a closed cooling medium circuit through which the first medium circulates. Advantageously, the first medium may comprise ammonium as a main component or consist of ammonium. Furthermore, the plate heat exchanger of the heat exchanger plant may advantageously comprise one or several of the features of the dependent claims 2 to 19.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now to be explained more closely by means of a description of various embodiments and with reference to the drawings attached hereto.

Fig. 1 discloses schematically a heat exchanger plant comprising a plate heat exchanger according to the invention.

Fig. 2 discloses schematically a side view of the plate heat exchanger in fig. 1.

Fig. 3 discloses schematically a front view of the plate heat exchanger in fig. 1 .

Fig. 4 discloses schematically a front view of a heat exchanger plate of the plate heat exchanger in figs 2 and 3.

Fig. 5 discloses schematically a front view of a first heat exchanger plate of a plate heat exchanger according to a second embodiment.

Fig. 6 discloses schematically a front view of a second heat exchanger plate of a plate heat exchanger according to the second embodiment.

Fig. 7 discloses a sectional view along the line VII-VII in fig. 3. DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

Fig. 1 discloses a heat exchanger plant comprising an evapora- tor 1 , a compressor 2, a condenser 3 and an expansion member 4. The evaporator 1 , the compressor 2, the condenser 3 and the expansion member 4 are connected to each other by means of a cooling medium conduit 5 and form a closed cooling medium circuit through which a first medium circulates. In the embodiments disclosed, the first medium comprises ammonium, as a main component, or consists of ammonium. The invention is applicable also to other cooling media than ammonium, for instance different kinds of freons. A second medium for heating of the cooling medium is also supplied to the evaporator 1 via an ex- ternal circuit 6. Also the condenser 3 is connected to an external circuit 7 for the supply of a third medium for cooling of the cooling medium.

In the following, the plate heat exchanger is to be explained more closely in an embodiment where it is used as an evaporator. However it is to be noted that the plate heat exchanger according to the invention also may be used as a condenser. The evaporator 1 is formed by a plate heat exchanger which is disclosed more closely in figs 2-7. The plate heat exchanger compri- ses a plate package 1 1 having a plurality of heat exchanger plates 12, 12a, 12b, see figs 4-7, which are provided beside each other in the plate package 1 1 in such a way that a plate interspace is formed between each pair of adjoining heat exchanger plates 12, 12a, 12b.

Every second plate interspace forms a first plate interspace a for the first medium to be evaporated and each of the remaining plate interspaces forms a second plate interspace 2 for the second medium, see fig. 7, in such a way that the first plate in- terspaces a and the second plate interspaces b are provided in an alternating order in the plate package 1 1 . Each of the heat exchanger plates 12, 12a, 12b extends in parallel or substantially in parallel with a main extension plane p. The plate heat exchanger may also comprise a frame plate 13 and a pressure plate 14, which are provided at a respective side of the heat exchanger plates 12, 12a, 12b. In the embodiments disclosed, the plate heat exchanger also comprises four strengthening plates 15, wherein two strengthening plates 15 are provided outside the frame plate 13 and two strengthening plates 15 are provide outside the pressure plate 14. It is to be noted that the two strengthening plates 15 on the same side of the frame plate and the pressure plate 14 may be designed as one single continuous strengthening plate.

In the embodiments disclosed, the heat exchanger plates 12, 12a, 12b, the frame plate 13, the pressure plate 14 and the strengthening plates 15 are permanently joined to each other, for instance by brazing and/or melting. Alternatively, the plates may be permanently connected to each other for instance thro- ugh gluing. The invention is also applicable to plate heat exchangers where the plates are pressed against each other by means of mechanical members, for instance tie bolts, wherein gaskets are provided between the plates for sealing of the plate interspaces in a manner known per se.

Each heat exchanger plate 12, 12a, 12b has a first end edge area 21 , a second end edge area 22, a first side edge area 23 and a second side edge area 24. Between the side edge areas 23 and 24, a heat exchanger surface 25 extends, which is provi- ded with a suitable corrugation of ridges and valleys for providing a desired heat transfer between the first medium and the second medium. Consequently, each or substantially each plate interspace a, b extends between the first side edge area 23 and the second side edge area 24 of the adjoining heat exchanger plates 12, 12a, 12b. Furthermore, each heat exchanger plate 12, 12a, 12b comprises four main portholes 31 , 32, 33 and 34, which form in the plate package 1 1 a first inlet port 41 , a first outlet port 42, a second inlet port 43 and a second outlet port 44. Each heat exchanger plate also comprises two further smaller portholes 35, 36, the function of which is explained more closely below. The first inlet port 41 extends through the plate package 1 1 and communicates with the first plate interspaces a for permitting supply of the first medium to the first plate interspaces a. The first outlet port 42 extends through the plate package 1 1 and communicates with the first plate interspaces a for permitting discharge of the first medium from the first plate interspaces a. The second inlet port 43 extends through the plate package 1 1 and communicates with the second plate interspaces b for permitting supply of the second medium to the second plate interspaces b. The second outlet port 44 extends through the plate package 1 1 and communicates with the second plate interspaces b for permitting discharge of the second medium from the second plate interspaces b. The first inlet port 41 of the plate package 1 1 is in the operating position located beneath the first outlet port 42 and at a lower end of the plate package 1 1.

It is to be noted that in the embodiments disclosed, the ports 41-

44 are arranged in such a way that the two media flow in a counter current flow, wherein the inlet and outlet ports for one and the same medium are located on the same side of the plate heat exchanger. It is also possible to provide the inlet and outlet ports for one and the same medium on a respective side of the plate heat exchanger, i.e. in a diagonal configuration. Further- more, it is to be noted that the ports 41-44 may be arranged so that the media flows in parallel to each other in the same direction.

The plate heat exchanger also comprises a drainage port 45, which extends through the plate package 1 1 . The drainage port

45 communicates with the first plate interspaces a and is closed in relation to the second plate interspaces b. The drainage port

45 is provided to permit discharge of a liquid collected in the first plate interspaces 45. The drainage port 45 is in the operating position located at a lower part of the plate package 1 1 and the plate heat exchanger, and more precisely beneath the first inlet port 41. In the embodiment disclosed regarding an evaporator 1 1 in a cooling medium circuit, oil from the oil-lubricated compressor 2 will accompany the cooling medium into the evaporator 1 . The oil will be collected at a lower part of the evapo- rator 1 in the first plate interspaces a. By means of the drainage port 51 disclosed, the collected oil may in an efficient and continuous manner be discharged from the first plate interspaces a.

The plate heat exchanger also comprises a degassing port 46 which extends through the plate package 1 1. The degassing port

46 communicates with the second plate interspaces b and is closed in relation to the first plate interspaces a. The degassing port 46 is provided to permit discharge of a gas collected in the second plate interspaces b. The degassing port 46 is in the ope- rating position located at an upper part of the plate heat exchanger and more precisely at the level of or above the second inlet port 43. By means of the degassing port 46 gas or air, which is present in the second medium and which is collected in an upper part of the second plate interspaces b, may be remo- ved, especially in connection with the start of the operation.

When the plate package 1 1 is mounted and the heat exchanger plates 12, 12a, 12b are provided beside each other, every second heat exchanger plate 12, 12a, 12b is rotated 180° in a pla- ne which is parallel with the extention plane b. Consequently, the first end edge area 21 of a heat exchanger plate 12, 12a, 12b will adjoin the second end edge area 22 of the adjoining heat exchanger plate 12, 12a, 12b. In a corresponding manner, the first inlet port 41 will be formed by the main portholes 31 and 33 in an alternating order. The drainage port 45 and the degassing port 46 will be formed by the further smaller portholes 35 and 36 in an alternating order. It is to be noted that the heat exchanger may be manufactured without the degassing port 46, for instance by covering the further portholes 35, 36 of the outer heat exchanger plates 12, 12a, 12b or the frame plate 13 and the pressure plate 14.

Fig. 4 discloses a first embodiment of a heat exchanger plate 12. According to this embodiment, all heat exchanger plates in the plate package 1 1 are identical or substantially identical. Every second plate 12 in the plate package is rotated 180° for obtaining crossing corrugations supporting each other.

Figs 5 and 6 disclose a second embodiment where two different heat exchanger plates 12a and 12b are used. According to this embodiment, the main porthole 31 in the heat exchanger plate 12a and the main porthole 33 in the heat exchanger plate 12b are smaller than the remaining main portholes 31 -34 of the two heat exchanger plates. These two smaller portholes 31 and 33 form the inlet port 41 for the first medium. As can be seen in figs 5 and 6, an inlet channel 60 extends from the port edge into the heat exchanger surface 25. This inlet channel 60 forms a guide member by means of which the first medium may be conveyed into the first plate interspaces a and be distributed therein. The inlet channel 60 is directed obliquely downwardly towards the lower end of the plate package 1 1 with respect to the operating position. The guide member may be designed in many various ways and for instance consist of a separate component provided in the first inlet port 41 as disclosed in fig. 3.

As can be seen in fig. 1 , the drainage port 45 may via a condit 50 be connected to the compressor 2 for suitable recirculation of the collected oil. The recirculation may take place by means of the gravity force if the compressor 2 is located at a lower level than the drainage port 45 or by means of a suitable pump 51 . When the plate heat exchanger operates as a condenser, every second plate interspace forms a first plate interspace a for the first medium to be condensed, and each of the remaining plate interspaces forms a second plate interspace b for the second medium in such a way that the first plate interspaces a and the second plate interspaces b are provided in an alternating order in the plate package.

In the condenser case, the flows are arranged in such a way that the portholes 31 , 32, 33 and 34 form a first outlet 41 , a first inlet port 42, a second inlet port 43 and a second outlet port 44. The first inlet port 42 extends through the plate package 1 1 and communicates with the first plate inter- spaces a for permitting supply of the first medium to the first plate interspaces a. The first outlet port 41 extends through the plate package 11 and communicates with the first plate interspaces a for permitting discharge of the first medium from the first plate interspaces a. The second inlet port 43 extends through the plate package 1 1 and communicates with the second plate interspaces b for per- mitting supply of the second medium to the second plate interspaces b. The second outlet port 44 extends through the plate package 1 1 and communicates with the second plate interspaces b for permitting discharge of the second medium from the second plate interspaces b. The first inlet port 42 of the plate package 1 1 is in the operating position located above the first outlet port 41 and at an upper end of the plate package 1 1 .

In the same way as when the heat exchanger operates as an evaporator, a drainage port 45 is formed by the smaller porthole 35 on the heat exchanger plate, and a degassing port 46 is formed by the smaller porthole 36 on the heat exchanger plate, which both extend through the plate package 1 1 . The drainage port 45 communicates with the first plate interspaces a and is closed in relation to the second plate interspaces b. The draina- ge port 45 is provided to permit discharge of a fluid collected in the first plate interspaces 45. Normally inert gases or light inso- luble oil are here collected. The drainage port 45 is in the operating position located at a lower part of the plate package 1 1 and the plate heat exchanger, and more precisely beneath the first outlet port 41 . In the embodiment disclosed regarding a conden- ser 3 in a cooling medium circuit, oil from the oil-lubricated compressor 2 will accompanying the medium into the condenser 3. The oil will together with inert gases be collected at a lower part of the condenser 3 in the first plate interspaces a. With the drainage port 45 disclosed the collected oil may be discharged in an efficient and continuous manner from the first plate interspaces a.

If high-molecular media are to be condensed in the plate heat exchanger, which normally is made at low circulation speeds, the degassing port 46 may be provided in such a way that it communicates with the first plate interspaces a and is closed in relation to the second plate interspaces b. The degassing port 46 is then provided to permit discharge of a gas collected in the first plate interspaces a. The degassing port 46 is in the opera- ting position located at an upper part of the plate heat exchanger, and more precisely at the level of or above the second inlet port 43. By means of the degassing port 46, gas or air, present in the first medium and collected in an upper part of the plate interspaces a, may be removed.

The invention is not limited to the embodiments disclosed but may be varied and modified within the scope of the following claims.

Claims

1. A plate heat exchanger comprising a plate package (1 1 ) having a plurality of heat exchanger plates (12, 12a, 12b) which are provided beside each other in the plate package (1 1 ) in such a way that a plate interspace is formed between each pair of adjoining heat exchanger plates (12, 12a, 12b),

wherein every second such plate interspace forms a first pla- te interspace (a) for a first medium and each of the remaining plate interspaces forms a second plate interspace (b) for a second medium, in such a way that the first plate interspaces (a) and the second plate interspaces (b) are provided in an alternating order in the plate package (1 1 ),

wherein each heat exchanger plate (12, 12a, 12b) comprises four portholes (31 , 32, 33, 34) which, in the plate package (1 1 ), form a first inlet port, which extends through the plate package (1 1 ) and communicates with the first plate interspa- ces (a) for permitting supply of the first medium to the first plate interspaces (a), a first outlet port, which extends through the plate package (1 1 ) and communicates with the first plate interspaces (a) for permitting discharge of the first medium from the first plate interspaces (a), and a second inlet port, which extends through the plate package (1 1 ) and communicates with the second plate interspaces (b) for permitting supply of the second medium to the second plate interspaces (b), and a second outlet port, which extends through the plate package (1 1 ) and communicates with the second plate inters- paces (b) for permitting discharge of the second medium from the second plate interspaces (b),

characterized in that the plate package (1 1 ) comprises a drainage port (45), which extends through the plate package (1 1 ) and communicates with the first plate interspaces (a) and is closed in relation to the second plate interspaces (b), wherein the drainage port (45) is provided to permit in an operating position discharge of a fluid collected in the first plate interspaces (a).

2. A plate heat exchanger according to claim 1 , characterized [n that the drainage port (45) in the operating position is located at a lower part of the plate heat exchanger.

3. A plate heat exchanger according to anyone of claims 1 and 2, characterized in that the drainage port (45) in the operating position is located beneath the first inlet port (41 ).

4. A plate heat exchanger according to anyone of claims 1 and 2, characterized in that the drainage port (45) in the ope- rating position is located beneath the first outlet port.

5. A plate heat exchanger according to anyone of claims 1 to

4, characterized in that each heat exchanger plate (12, 12a, 12b) comprises at least one further porthole (35, 36), wherein the further portholes (35,36) form the drainage port (45) through the plate package (1 1 ).

6. A plate heat exchanger according to anyone of claims 1 to

5, characterized in that the plate package (1 1 ) comprises a degassing port (46), which extends through the plate package

(11 ) and communicates with the second plate interspaces (b) and is closed in relation to the first plate interspaces (a), wherein the degassing port (46) is provided to permit discharge of a gas collected in the second plate interspaces (b).

7. A plate heat exchanger according to anyone of claims 1 to 5, characterized in that the plate package (1 1 ) comprises a degassing port (46), which extends through the plate package (1 1 ) and communicates with the first plate interspaces (a) and is closed in relation to the second plate interspaces (b), whe- rein the degassing port (46) is provided to permit discharge of a gas collected in the first plate interspaces (a).

8. A plate heat exchanger according to claims 5 and 6, cha- racterized in that each heat exchanger plate comprises two further portholes (35, 36), wherein the further portholes (35,

36) form the drainage port (45) and the degassing port (46) through the plate package (1 1 ).

9. A plate heat exchanger according to anyone of claims 6 to

8, characterized in that the degassing port (46) in the operating position is located at an upper part of the plate heat exchanger.

10. A plate heat exchanger according to anyone of claims 6 to

9, characterized in that the degassing port (46) in the operating position is located at the level of or above the second inlet port (43).

11. A plate heat exchanger according to anyone of the preceding claims, characterized in that each heat exchanger plate has a first end edge area (21 ) and a second end edge area (22), and a first side edge area (23) and a second side edge area (24).

12. A plate heat exchanger according to claim 1 1 , characterized in that each or substantially each plate interspace (1 1 ) extends between the first side edge area (23) and the second side edge area (24) of an adjoining heat exchanger plate (12, 12a, 12b).

13. A plate heat exchanger according to anyone of the preceding claims, characterized in that the first inlet port in the operating position is located beneath the first outlet port when the plate heat exchanger operates as an evaporator.

14. A plate heat exchanger according to claim 13, characterized in that the first inlet port is located at a lower end of the plate package (1 1 ) with regard to the operating position.

15. A plate heat exchanger according to anyone of claims 1 to 12, characterized in that the first inlet port in the operating position is located above the first outlet port when the plate heat exchanger operates as a condenser.

16. A plate heat exchanger according to claim 15, characterized in that the first inlet port is located at an upper end of the plate package (1 1 ) with respect to the operating position.

17. A plate heat exchanger according to claim 14, characteri- zed in that the plate heat exchanger comprises a guide member (60) in the first inlet port, which is arranged to guide the first medium into the first plate interspaces (a) towards the lower end of the plate package (1 1 ).

18. A plate heat exchanger according to anyone of claims 1 -3, 5-6, 8-14 or 17, characterized in that it is adapted to operate in the operating position as an evaporator, wherein the first plate interspaces (a) are arranged to permit evaporation of the first medium.

19. A plate heat exchanger according to anyone of claims 1 -2, 4-12 or 15-16, characterized in that it is adapted to operate in the operating position as a condenser, wherein the first plate interspaces (a) are arranged to permit condensation of the first medium.

20. A heat exchanger plant comprising an oil-lubricated compressor (2) and a plate heat exchanger comprising a plate package (1 1 ) having a plurality of heat exchanger plates (12, 12a, 12b), which are provided beside each other in the plate package (1 1 ) in such a way that a plate interspace is formed between each pair of adjoining heat exchanger plates (12, 12a, 12b),

characterized in that the plate package (1 1 ) comprises a drainage port (45), which extends through the plate package (1 1 ) and communicates with the first plate interspaces (a) and is closed in relation to the second plate interspaces (b), wherein the drainage port (45) is provided to permit discharge of a liquid collected in the first plate interspaces (a).

21. A heat exchanger plant according to claim 20, characterized in that the drainage port (45) is connected to the compressor (2) for suitable recirculation of the collected fluid.

22. A heat exchanger plant according to anyone of claims 20 and 21 , characterized in that the heat exchanger plant also comprises a condenser (3) and an expansion member (4), wherein the plate heat exchanger, the compressor, the condenser and the expansion member form a closed cooling me- dium circuit through which the first medium circulates.

23. A heat exchanger plant according to anyone of claims 20 and 21 , characterized in that the plate heat exchanger forms a condenser (3) and that the heat exchanger plant also compri- ses an evaporator (1 ) and an expansion member (4), wherein the plate heat exchanger, the compressor, the condenser and the expansion member form a closed cooling medium circuit through which the first medium circulates.

24. A heat exchanger plant according to anyone of claims 20 to 23, characterized in that the first medium comprises ammonium as a main component.

25. A heat exchanger plant according to anyone of claims 20 to 21 , characterized in that the plate heat exchanger comprises one or several of the features in the claims 2 to 19.