Heat transfer plate and plate heat exchanger with gasket groove having a reinforcing pattern

A plate heat exchanger includes a plurality of heat transfer plates stacked on top of each other, wherein gaskets are positioned between adjacent heat transfer plates, wherein each gasket is arranged in a gasket groove formed in a heat transfer plate and a bottom part of the gasket groove defines a base level, wherein the gasket groove comprises a reinforcing pattern having a first recess at a first recess level and extending in a lengthwise direction of the gasket groove. The reinforcing pattern comprises a second recess at a second recess level extending in lengthwise direction of the gasket groove.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims foreign priority benefits under 35 U.S.C. § 119 to Danish Patent Application No. PA201800920 filed on Nov. 27, 2018, the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a plate heat exchanger comprising a plurality of heat transfer plates stacked on top of each other, wherein gaskets are positioned between adjacent plates, wherein each gasket is arranged in a gasket groove formed in a heat transfer plate and a bottom part of the gasket groove defines a base level, wherein the gasket groove comprises a reinforcing pattern having a first recess at a first recess level and extending in a lengthwise direction of the gasket groove.

BACKGROUND

Such a plate heat exchanger is known, for example, from EP 0 604 499 B1.

Such a type of a plate heat exchanger comprises a plurality of heat transfer plates stacked on top of each other. The heat transfer plates are formed with patterns such that flow paths are formed between each set of neighbouring heat transfer plates. Openings are formed in the heat transfer plates to form inlets and outlets for fluids to these flow paths. As a rule, a pair of openings is provided for the primary side of the heat exchanger and another pair of openings is provided for the secondary side of the heat exchanger. Gaskets are positioned between the heat transfer plates. A part of the gasket is used to seal the space between two heat transfer plates to the outside. Another part (or another gasket) is used to seal a region of the openings the primary side from the secondary side. Thus, the gaskets are arranged at an edge portion of the heat transfer plates so seal the flow paths to the outside and at an area around the openings to seal pairs of the openings, such that only two of them have flow access to the flow path formed at one side of the heat transfer plate, while the other two openings are sealed therefrom.

Especially in the opening areas the pressures are high, but the gasket is disposed at only one side of the heat transfer plate, while the other side is unsupported to allow a flow of fluid from the respective opening into the respective flow path. Thus, this part forms a weak section, these weak sections in the areas of the high pressures may be deformed. Further, the gasket tends to be pushed out of position by the pressures in these areas, leading to the risk of a leakage to the outside and to the risk of a leakage between the primary side and the secondary side.

SUMMARY

The object underlying the invention is to make a plate type heat exchanger suitable for high pressures without increasing the risk of leakages.

This object is solved with a plate heat exchanger as described at the outset in that the reinforcing pattern comprises a second recess at a second recess level extending in lengthwise direction of the gasket groove.

The second recess can be used to adapt the reinforcement of the groove caused by the recesses to specific requirements in certain parts of the heat transfer plate.

In an embodiment of the invention the base level is defined by a bottom of the gasket groove in an edge part running along an edge of the heat transfer plate. In the edge part of the groove the recesses are not absolutely necessary, although they can be provided even in the edge part of the groove. The edge part of the groove does define a level, from which the recesses extend.

In an embodiment of the invention the second recess extends in a direction opposite to the first recess from the first recess. In this way the first recess may comprise at least two parallel recessed parts at the first level. In other words, the first recess forms two “rails” in the bottom part of the groove. Accordingly, there are two additional sections of the heat transfer plates running under an angle, preferably perpendicular, to the plane of the heat transfer plate.

In an embodiment of the invention a first portion of the gasket groove surrounds an opening of the heat exchanger plate, wherein the first portion comprises the two parallel recessed parts at the first level. The area around the opening is the area which is subjected to the highest pressure. The recess having the two parallel recessed parts at the first level, i.e. the second recess in opposite direction, gives an excellent reinforcing of the groove.

In an embodiment of the invention the gasket groove comprises a second part running diagonal to an edge portion of the heat transfer plate and being connected to the first portion. The second part can as well be termed “diagonal part”. The diagonal part is used alternately, i.e. every second space adjacent to heat transfer plates is filled with a gasket while the diagonal part in the other spaces is not filled with a gasket, so that a fluid connection between the opening and the fluid paths can be established.

In an embodiment of the invention the second portion extends into the edge part. The gasket can continue from the second portion into the edge part.

In an embodiment of the invention the second recess extends downwardly from the first recess. This means that there is a groove having a bottom which is at least twice stacked. This increases the stability of the groove.

In an embodiment of the invention the first recess comprises a first height and the second recess comprises a second height, wherein the first height is different from the second height. This allows a variation of the reinforcement of the gasket groove.

In an embodiment of the invention the heat transfer plate comprises corrugations having troughs and crests, wherein the troughs continue into the gasket groove. This has the advantage, that the gasket, when compressed between two adjacent heat transfer plates, can be squeezed into the troughs which increases the sealing capacity of the gasket and holds the gasket in place.

In an embodiment of the invention at least one of the recesses continues into the troughs. The troughs are likewise reinforced in the area of the recesses.

In an embodiment of the invention the first recess and the second recess extend in different directions from the base level. This means that one recess extends downwardly from the base level and the other recess extends upwardly from the base level.

In an embodiment of the invention the first recess runs along a first section of the gasket groove and the second recess runs along a second section of the gasket groove, wherein the first section is different from the second section. In other words, the two recesses are not arranged in the same section or area of the groove.

In an embodiment of the invention the first section is arranged in one half of the heat transfer plate and the second section is arranged in the other half of the heat transfer plate. This embodiment is in particular advantageous, when adjacent heat transfer plates are stacked on top of each other with inversed orientation. In this case the one half of one heat transfer plate and the second half of another heat transfer plate are positioned above each other giving the possibility to squeeze a gasket between the first recess and the second recess.

In an embodiment of the invention at least one recess reaches into the edge part of a gasket groove. This does not necessarily mean that the recess extends along the whole edge part. However, the recess produces a reinforcement of the transition between the edge part of the gasket groove and another part of the gasket groove.

DETAILED DESCRIPTION

FIG.1shows schematically a heat exchanger1comprising a number of heat transfer plates10which are stacked one on top of the other. The stack of heat transfer plates is arranged between a top plate4and a bottom plate5.

The heat exchanger1comprises four openings for inlet and outlet of the fluids. Two openings2,3which are shown inFIG.1are used for the fluid passing the primary side of the heat exchanger1. Two other openings6,7(FIG.2only) are used for inlet and outlet of the fluid passing the secondary side of the heat exchanger.

FIG.2schematically shows a stack of four heat transfer plates10. The heat transfer plates10are laterally offset to each other in order to show some details.

Each heat transfer plate10is provided with a gasket8. The gasket8in all heat transfer plates runs along an edge9of the heat transfer plates. However, in a half of the number of the heat transfer plates10the gasket8leaves open a connection between the openings2,3and an interior of the space between two adjacent plates for the primary side and (which is not visible inFIG.2) in the other half, i.e. in every second plate the gasket8leaves open a connection between the openings6,7and the interior of the space between adjacent plates10to allow a flow of fluid through the secondary side of the heat exchanger.

The gasket8is mounted in a groove.

As can be seen inFIG.2, each heat transfer plate10comprises a part11of the groove, which is not filled by the gasket. Accordingly, the bottom of the part11of the groove which is free of the gasket8is not supported against a pressure acting between adjacent heat transfer plates. This can lead to a deformation of the heat transfer plate in the region of the part11of the groove with a resulting leakage. It can also lead to the effect that the gasket8is pushed out of position by the pressure in these areas.

This effect is schematically shown inFIG.3in which a gap12has appeared between the gasket8and the bottom side of the bottom of the part11of the groove of the next plate10above the gasket8.

To overcome this problem, the heat transfer plate10of the heat exchanger1is provided with a reinforced gasket groove20which is shown in several sectional views inFIG.5. The sections are taken from a heat transfer plate10shown inFIG.4.FIG.4shows the heat transfer plate10from the underside.

FIG.5Ashows the reinforced gasket groove20in an area running along the edge9.

The reinforced gasket groove20comprises a bottom21which defines a base level. The base level22is shown inFIG.5B to5Dwith a dotted line.

As can be seen inFIG.5B, showing a section along line B according toFIG.4, reinforced gasket groove20comprises a first recess comprising two parallel recessed parts23,24. These recessed parts23,24have a first recess level which is below the base level22. The recessed parts23,24are separated by a second recess25extending from the bottom of the first recess in opposite direction to the first recess.

FIG.5Cshows a section along line C ofFIG.4and shows a first recess23at a first recess level below the base level22and a second recess25at a second recess level below the first recess level of the first recess23.

The first recess23,24and the second recess25run along the lengthwise direction of the reinforced gasket groove20.

FIG.5Dshows a sectional view along line D inFIG.4.

It can be seen inFIG.4that the heat transfer plate10comprises corrugations having crests26and troughs27. It should be noted thatFIG.4shows the heat transfer plate10from the bottom so that crests26and troughs27appear to be inverted.

The reinforced gasket groove20extends into the crests26and the first recess23extends into the troughs27as well.

As can be seen, in particular inFIG.4, a gasket groove20surrounds an opening2of the heat transfer plate10, wherein the form of the gasket groove20in this area is shown inFIG.5B, i.e. the gasket groove20comprises two first recesses23,24extending below the base level22to the first recess level.

FIG.6shows a slightly modified heat transfer plate10from the bottom, in which the gasket groove20comprises the ring-shaped part28surrounding the opening2and a diagonal part29. The diagonal part29extends into an edge part30of the groove. A first recess23extends at least partly as well in the edge part30of the groove.

As can be seen inFIG.5C, the first recess23comprises a first height and the second recess comprises a second height. The first height is different from the second height. In the example shown inFIG.5Cthe second height is smaller than the first height. However, it is also possible that the first height is smaller than the second height.

As shown in the figures, it is also possible that the first recess23extends downwardly from the base level22in a first section of the gasket groove20. This is shown inFIG.5B to5D. In a way not shown, the second section of the gasket groove20can have a second recess extending upwardly from the base level22. When heat transfer plates10are stacked above each other, then a gasket8arranged in a gasket groove20is compressed more intensively, since the space available for the gasket8, more precisely the height, has been decreased.

This is in particular the case, when the first section is arranged in one half of the heat transfer plate10and the second section is arranged in the other half of the heat transfer plate10and every second heat transfer plate10is rotated by 180° before stacking it to the previous plate10.