Plate heat exchanger

THE FIELD OF THE INVENTION

The present invention refers to a plate heat exchanger comprising a plurality of heat exchanger plates according to the preamble of claim 1 . Such plate heat exchangers may be used in various fields, for instance in the combustion gas channel of combustion plants for gaining heat energy from the combustion gases.

THE BACKGROUND OF THE INVENTION AND PRIOR ART

In plate heat exchangers of the kind mentioned above, which are open outwardly to the surrounding edge side and which do not have any downwardly bent flange along the edge of each heat exchanger plate, it is difficult to guide the heat exchanger plates in connection with the mounting of the plate package. Consequently, it is difficult to provide a correct position for each individual heat exchanger plate in relation to the other heat exchanger plates when the plate package is mounted and during the joining of the heat exchanger plates to each other, for instance during a following brazing of the plate package. The guiding and the positioning of the heat exchanger plates require with the technique of today use of external guiding elements of various kinds.

US-A-5,918,664 discloses a plate heat exchanger of the kind initially defined, which comprises a plurality of heat exchanger plates. Each of the heat exchanger plates extends in parallel with a main extension plane. The heat exchanger plates are provided beside each other so that they form a plate package having an surrounding edge side and first plate interspaces for a first medium and second plate interspaces for a second medium.

Every second heat exchanger plate is formed by a first of said heat exchanger plates and the remaining heat exchanger plates are formed by a second heat exchanger plate in such a way that such a first heat exchanger plate together with such a second heat exchanger plate form a pair of heat exchanger plates, which encloses such a first plate interspace, and that the plate package comprises a plurality of such pairs of heat exchanger plates. Each of the heat exchanger plates has at least two portholes forming ports extending through the plate package and communicating with the first plate interspaces. The heat exchanger plates are configured in such a way that the second plate interspaces are open through the surrounding edge side.

US-A-5,967,227 discloses a plate heat exchanger of another kind comprising a plurality of heat exchanger plates which each extends in parallel with a main extension plane. The heat exchanger plates are provided beside each other in an alternating order for forming a plate package. The heat exchanger plates form first plate interspaces for a first medium and second plate interspaces for a second medium. The first and second plate interspaces are sealed by means of surrounding gaskets. Each of the heat exchanger plates has two portholes, which form ports extending through the plate package and communicating with the first plate interspaces, and two portholes, which form ports extending through the plate package and communicating with the first plate interspaces. Each heat exchanger plate comprises a bent part in each corner, which cooperates with a corresponding bent part of the adjoining heat exchanger plates in the plate package.

SUMMARY OF THE INVENTION

The object of the present invention is to overcome the problems mentioned above and to facilitate the guiding and the positioning of the heat exchanger plates in connection with the mounting and the joining of the plate package.

This object is achieved by a plate heat exchanger of the kind initially defined, which is characterized in that each of the portholes of such a first heat exchanger plate is configured in such a way that it cooperates with an opposite porthole of such a second heat exchanger plate in order to ensure that each pair of heat exchanger plates takes a determined position in relation to adjoining pairs of heat exchanger plates.

By means of two such bent parts cooperating with each other when a first heat exchanger plate is laid against a second heat exchanger plate, it may be ensured that the two heat exchanger plates are guided to a correct position and that this position is maintained during the whole mounting and joining of the plate package and the plate heat exchanger. When the two heat exchanger plates have been attached to each other, the two bent parts may prevent them from being displaced or rotated in relation to each other in a plane parallel to the extension plane. Furthermore, a correct positioning of the different pairs in relation to each other is facilitated thanks to the fact that the portholes are designed to cooperate with a corresponding porthole of an adjoining pair in the plate package. The portholes will thus contribute to the guiding of the pairs of heat exchanger plates to a determined position in relation to each other and to the maintaining of this position of the pairs of heat exchanger plates during the whole manufacturing process.

According an embodiment of the invention, each first and second heat exchanger plate has a compression-moulded pattern, which extends in a pressing direction with regard to the extension plane, wherein the first bent part extends in a first direction with regard to the extension plane of the first heat exchanger plate and the second bent part extends in a second direction with regard to the extension plate of the second heat exchanger plate, and wherein the second direction extends in the same direction as the pressing direction but is opposite to

the first direction. Since the bent parts extend in different directions in relation to the extension plane and in relation to the heat exchanging pattern and port areas of the compression- moulded plate, the bent parts are advantageously produced in a shaping operation after the main compression-moulding of the pattern and port areas of the plate. The first direction and the second direction may then extend transversally or substantially transversally to the extension plane. Furthermore, each second heat exchanger plate may be rotated 180° in relation to each first heat exchanger plate in the finished plate package. In such a way the first bent part and the second bent part will extend in the same direction in the finished plate package, which makes it possible to provide a proper form fitting and a proper form locking between the first and second bent parts and thus between the first and second heat exchanger plates in each pair.

According to a further embodiment of the invention, each heat exchanger plate extends along a longitudinal centre line, which extends through the bent part. Furthermore, each second heat exchanger plate in the plate package may be rotated 180° around the centre line of the heat exchanger plate.

According to a further embodiment of the invention, the first and second heat exchanger plates are permanently joined to each other in the plate package. Such a permanently joined plate package may be achieved by means of brazing, gluing or welding.

According to a further embodiment of the invention, each first heat exchanger plate comprises two first bent parts and each second heat exchanger plate two second bent parts. Two such bent parts of each heat exchanger plate are sufficient for ensuring the above mentioned positioning of the heat exchanger plates in relation to each other.

According to a further embodiment of the invention, the two first bent parts are provided opposite to each other along a respective edge of the first heat exchanger plate and the two second bent parts are provided opposite to each other along a respective edge of the second heat exchanger plate.

According to a further embodiment of the invention, each portholes comprises a surrounding port area, wherein the port area around a first porthole of each heat exchanger plate is located at a first level with regard to the extension plane, and the port area around a second of said portholes of each heat exchanger plate is located at another level with regard to the extension plane. Advantageously, the port area around the first porthole of a first pair of heat exchanger plates may be configured in such a way that it is in engagement with the port area around the second porthole of an adjoining second pair of heat exchanger plates. The port area around the second porthole of the first pair of heat exchanger plates may then be configured in such a way that it is in engagement with the port area around the first porthole of the adjoining second pair of heat exchanger plates. In such a way, the portholes may contribute to the guiding of the pairs of heat exchanger plates to a determined position in relation to each other and to the maintaining of this position of the pairs of heat exchangers plates during the whole manufacturing process.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is now to be explained more closely through a description of non-limiting embodiments and with reference to the drawings attached.

Fig. 1 discloses an exploded perspective view of a plate heat exchanger according to an embodiment of the invention.

Fig. 2 discloses a view from above of the plate heat exchanger in Fig. 1 .

Fig. 3 discloses a section through the plate heat exchanger along the line Ill-Ill in Fig. 2.

Fig. 4 discloses a section through the plate heat exchanger along the line IV-IV in Fig. 2.

Fig. 5 discloses more closely a part of an edge area V of the plate heat exchanger.

Fig. 6 discloses a simplified exploded perspective view of a plate package of a plate heat exchanger according to the invention.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

With reference to Figs. 1-5 an embodiment of a plate heat exchanger is disclosed. The plate heat exchanger comprises a plurality of heat exchanger plates 1 , 2. The heat exchanger plates 1 , 2 consists of first heat exchanger plates 1 and second heat exchanger plates 2. All heat exchanger plates 1 , 2 have a heat exchanging function in the plate heat exchanger. Each heat exchanger plate 1 , 2 extends in parallel with a main extension plane p, see Fig. 3. The extension plane p may be regarded as extending through and in parallel with a basic plane of each heat exchanger plate 1 , 2, from which each plane heat exchanger plate 1 , 2 has been compression-moulded in a manner known per se for achieving a compression-moulded pattern including a heat exchanging pattern with corrugations and a port area pattern.

The heat exchanger plates 1 , 2 are provided beside each other in such a way that they form a plate package 3 having an edge

side 4, which extends around the plate package 3. The heat exchanger plates 1 , 2 form, in the plate package 3, first plate interspaces 5 for a first medium and second plate interspaces 6 for a second medium, see Fig. 3. The heat exchanger plates 1 , 2 are also provided in such a way in the plate package 3 that every second heat exchanger plate is a first heat exchanger plate 1 and the remaining heat exchanger plates are a second heat exchanger plate 2. As can be seen especially from Figs. 1 and 3, a first heat exchanger plate 1 and an adjoining second heat exchanger plate 2 form a pair of heat exchanger plates in the plate package 3 in such a way that this pair of heat exchanger plates encloses a first plate interspace 5. As can be seen, the plate package 3 comprises in the embodiment disclosed three such pairs of heat exchangers plates 1 , 2. It is to be noted here that the plate heat exchanger of course may comprise fewer or more such pairs of heat exchanger plates 1 , 2 depending on the specific application for the plate heat exchanger.

In the embodiment disclosed, each heat exchanger plate 1 , 2 has two portholes 8, 9, which form ports extending through the plate package 3 and communicating with the first plate interspaces 5. One of the portholes 8, 9 thus forms an inlet port for the first medium to the first plate interspaces 5 whereas the other porthole 9 forms an outlet port for the first medium from the first plate interspace 5.

The heat exchanger plates 1 , 2 are configured in such a way that the second plate interspaces 6 are open through the surrounding edge side 4. The second medium may thus flow freely in through the edge side 4 of the plate heat exchanger into the second plate interspaces 6 and out through the edge side 4. Depending on how the plate heat exchanger is arranged in relation to the flowing of the second medium, the flow direction of the second medium through the plate heat exchanger may be determined.

Each porthole 8, 9 comprises a surrounding port area 10, 1 1 . The port area 10 around the first porthole 8 of each heat exchanger plate 1 , 2 is located at a first level p' with regard to the extension plane p, and the second port area 1 1 around the second porthole 9 of each heat exchanger plate 1 , 2 is located at a second level p" with regard to the extension plane p, see Fig. 3. In the embodiment disclosed, both port areas 10, 1 1 are located on the same side of the extension plane p wherein the level p' is located more far away from the extension plane p than the level p".

The plate heat exchanger also comprises a frame plate 13 and a pressure plate 14, which do not have any heat exchanging function. The pressure plate 14 has in the embodiments disclosed no portholes whereas the frame plate 13 has portholes being concentric to the portholes 8 and 9, respectively. Connection pipes 15 and 16 are connected to the frame plate 13 for permitting communication with a respective one of the above-mentioned ports.

Each first heat exchanger plate 1 comprises two first bent parts 21 and each second heat exchanger plate 2 comprises two second bent parts 22. The first bent part 21 is arranged to cooperate with the second bent part 22 of each such pair of heat exchanger plates 1 , 2 in order to ensure that the heat exchanger plates 1 and 2 in each pair takes a determined position in relation to each other and that this position is maintained during the whole manufacturing process of the plate heat exchanger.

In the embodiment disclosed, the first bent parts 21 extend in a first direction with regard to the extension plane p of the first heat exchanger plate 1 and more precisely away from the extension plane p. The second bent part 22 extends in a second direction with regard to the extension plane p of the second heat exchanger plate 2, i.e. away from the extension plane p. The

second direction is opposite to the first direction with regard to the extension plane p. In the embodiment disclosed in Figs. 1-5, the first direction is opposite to the above-mentioned pressing direction. The second bent part 22 thus extends in the same direction, or substantially the same direction, as the compression-moulded pattern and port areas 10, 1 1 of the heat exchanger plates 1 , 2. The first direction and the second direction extend transversally or substantially transversally to the extension plane p. All heat exchanger plates 1 , 2 in the plate package 3 are thus identical except with regard to the bent parts 21 , 22 extending in opposite directions.

When the plate heat exchanger is mounted, every second heat exchanger plate 2 is rotated 180° in relation to every first heat exchanger plate 1. After this rotation of the second heat exchanger plates 2, the first bent part 21 and the second bent part 22 will thus extend in the same direction in the finished plate package 3, see especially Fig. 5. Each heat exchanger plate 1 , 2 extends along a longitudinal centre line x which is parallel with the extension plane p. The second heat exchanger plates 2 are in the plate package rotated 180° around the respective centre line x. Fig. 6 discloses schematically in a simplified manner a plate package 3 having two pairs of heat exchanger plates 1 , 2, where the second heat exchanger plates 2 have been rotated 180° around the centre line x. The bent parts 21 , 22 thus extend in the same direction in the plate package 3.

As can be seen from Figs. 1 , 2 and 6, the first parts 21 of each first heat exchanger plate 1 are provided opposite to each other along a respective edge 23 of the first heat exchanger plate 1 .

More precisely, each first bent part 21 is concentrically provided with regard to the longitudinal centre line x in such a way that the centre line x extends centrally through the first bent part 21 . In the same way, the second parts 22 of each second heat exchanger plate 2 are provided opposite to each other along a

respective edge of the second heat exchanger plate 2. More precisely, each second bent part 22 is concentrically provided with regard to the longitudinal centre line x in such a way that the centre line x extends centrally through the second bent part 22.

Each heat exchanger plate has in the embodiment disclosed in Figs. 1-5 two opposite short edges 23 and two opposite long edges 24. As can be seen the first and second parts 21 , 22 are provided at the two short edges 23. It is of course possible, as an alternative with two bent parts of each heat exchanger plate or a supplement with four bent parts of each heat exchanger plate, to provide bent parts along the long edges 24.

In the embodiment disclosed, each heat exchanger plate 1 , 2 has an edge area 25 adjoining the short and long edges 23, 24 and extending around the compression-moulded pattern and port areas 10, 1 1 of the heat exchanger plate 1 , 2. The edge area 25 is substantially plane and parallel with the extension plane p. In the embodiment disclosed, the extension plane p also lies in the edge area 25. As can be seen from Fig. 3, the edge area 25 of the first heat exchanger plate 1 abuts, in each pair of heat exchanger plates 1 , 2, the edge area 25 of the second heat exchanger plate 2.

The plate heat exchanger thus comprises the above-mentioned pairs of heat exchanger plates 21 , 22. These pairs are disposed beside each other in the plate package. Each of the portholes 8, 9 of the first heat exchanger plate 1 of such a pair is thus configured in such a way that it cooperates with an opposite porthole 8, 9 of the second heat exchanger plate 2 of an adjoining such pair in order to ensure that each pair of heat exchanger plates 1 , 2 takes a determined position in relation to adjoining pairs of heat exchanger plates 1 , 2. More specifically, the port area 10 around the first porthole 8 of a first pair of heat exchanger plates 1 , 2 is configured in such a way that it is in

engagement with the port area 1 1 around the second porthole 9 of an adjoining second pair of heat exchanger plates 1 , 2. The port area 1 1 around the second porthole 9 of the first pair is then configured in such a way that it is in engagement with the port area 10 around the first porthole 8 of the second pair.

Thanks to the guiding of the heat exchanger plates 1 , 2 achieved by means of the bent parts 21 , 22 and the port areas 10, 1 1 , all parts of the plate package 3, i.e. at least all heat exchanger plates 1 , 2 and possibly also the frame plate 13, the pressure plate 14 and the connection pipes 15, 16, may be mounted and disposed in their final position with a suitable braze material between the parts, whereafter the plate package 3 is disposed in an oven and brazed in a manner known per se. It is also imaginable to braze in a first step two heat exchanger plates 1 , 2 to the above-mentioned pairs and in a second step braze the pairs so formed. Other joining methods than brazing may also be used, for instance welding or gluing.

According to another alternative embodiment, the bent parts 21 and 22 may extend in the same direction away from the extension plane p. When the plate package 3 is mounted, wherein every second heat exchanger plate is rotated 180°, the bent parts 21 , 22 of the heat exchanger plates 1 , 2 in each pair will extend in opposite directions towards each other. In order to achieve a locking of the position, the bent parts 21 , 22 may then be displaced from the centre line x in such a way that they adjoin the centre line x. This embodiments has the advantage that all heat exchanger plates 1 , 2 may be made completely identical. Possibly the locking of the position may be improved if there are bent parts along each edge 23, 24.

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