TECHNICAL FIELD

The invention relates to a gasket arrangement for sealing between two heat transfer plates of a plate heat exchanger, and a heat transfer plate arranged to cooperate with a gasket arrangement. The invention also relates to a kit comprising such a gasket arrangement, an assembly comprising such a gasket arrangement and such a heat transfer plate, a heat exchanger comprising such a gasket arrangement and such a heat transfer plate and a method of refurbishing such assembly.

BACKGROUND ART

Plate heat exchangers, PHEs, typically consist of two end plates in between which a number of heat transfer plates are arranged in an aligned manner, i.e. in a stack. In one type of well-known PHEs, the so called gasketed PHEs, gaskets are arranged between the heat transfer plates, typically in gasket grooves which extend along edges of the heat transfer plates. The end plates, and therefore the heat transfer plates, are pressed towards each other whereby the gaskets seal between the heat transfer plates. The gaskets define parallel flow channels between the heat transfer plates through which channels two fluids of initially different temperatures alternately can flow for transferring heat from one fluid to the other. For the channels not to leak it is naturally essential that the gaskets are properly positioned between the plates.

When the plate heat exchanger is closed, the gaskets are squeezed between the plates and thereby securely held in place. However, when the gaskets are not squeezed between the plates, such as when the plate heat exchanger is assembled or open for maintenance, some kind of means for fixing the gaskets correctly to the plates is desirable. It is known to apply an adhesive in the gasket groove of a heat transfer plate to attach a gasket in the gasket groove. However, the adhesive may negatively affect the gasket and its sealing capability. The adhesive may also make it cumbersome to replace the gasket when required, since such replacement typically requires complete removal of old adhesive from the gasket groove to enable proper application of a new gasket in the gasket groove. Also, mechanical gasket fixing solutions are previously known, for example through applicant’s own US Patent No. 4,635,715. This document discloses a gasket provided with securing means projecting from an outside of the gasket, which securing means are arranged to be positioned around an edge of a heat transfer plate to secure the gasket to the heat transfer plate. The securing means are capable of effectively fixing, to the heat transfer plate, portions of the gasket arranged along, and close to, an outer edge, or an internal edge for e.g., a port hole, of the heat transfer plate. However, for fixing, to the heat transfer plate, portions of the gasket not arranged to extend along and close to, the edge of the heat transfer plate, the securing means according to US Patent No. 4,635,715 are less useful.

Reference is also made to the applicants own European patent application EP4001816. It relates to a gasket arrangement having an attachment part being enclosed by an outer sealing portion and arranged on an outside of an inner sealing portion. The attachment part comprises a fastening attachment portion arranged to be fastened to the surface of a heat transfer plate by means of an adhesive means.

Having the attachment part arranged on an outside of an inner sealing portion means that the flow inside the inner sealing portion is not disturbed. However, in some cases there is a flow on the outside of the inner sealing portion, and it may be undesirable to have the attachment part projecting on the outside of the inner sealing portion.

One example of heat exchanging plates having flow on both sides of a sealing gasket is found in applicants own EP 1864069 relating to a heat exchanger for desalination of sea water. The heat exchanger comprises a plate package including an evaporation section, a separation section, and a condensation section. Further prior art including WO2010013608 which describes a plate heat exchanger used as a freshwater generator having a cord member of heat resistant rubber having an integral plate shaped piece which is bonded to the heat exchange plate by adhesive or double-sided adhesive tape.

However, the plate shaped piece extends on both sides of the cord member. According to the present invention disclosure, the gasket attachment means only extends on one side of the gasket, namely the inwardly facing direction. This is beneficial for avoiding flow disturbance outside the gasket and improve the flow distribution in the area enclosed by the gasket. https://andersondahlen.com/product/apv-model-r5-phe-spares, shows a gasket having minor tabs in the distribution area.

The applicants own W02020108985 and W02020108983 have tabs extending inwardly from the gasket, but they are not fastened by adhesive means and only provided for stability. The document CH284574 describes a plate heat exchanger having gasket with engaging shoulders for gasket groove junction points where the gaskets have insufficient support.

The object of the present invention is therefore to provide technologies that offers a reliable fastening of the gasket arrangement to a heat transfer plate, along inner portions of the gasket arrangement, which fastening does not negatively affect the gasket or its sealing capability or make gasket replacement difficult. Other objects of the present invention are to provide a heat transfer plate arranged to cooperate with a gasket arrangement, a kit comprising a gasket arrangement and an assembly comprising a gasket arrangement and a heat transfer plate, a heat exchanger, and a method. SUMMARY

The above object is in a first aspect realized by a gasket arrangement for sealing between two corrugated heat transfer plates of a plate heat exchanger, the heat transfer plates each comprising a set of port holes, the gasket arrangement comprising: an annular sealing part being arranged to enclose the set of portholes of the heat transfer plates and define a flow path between the port holes of the set of port holes, and an attachment part connected to an inside of the annular sealing part and extending in an inwards direction relative to the annular sealing part, the attachment part defining a gasket attachment surface arranged to attach by an adhesive to a corresponding plate attachment surface of one of the heat transfer plates. The basic concept according to the invention is to provide the gasket arrangement with a non-sealing attachment part at a portion of the gasket arrangement arranged to extend along an inside of the annular sealing part, which attachment part is arranged to be fastened to the heat transfer plate by means of an adhesive means to secure the gasket arrangement to the heat transfer plate.

The corrugated heat transfer plate comprises at least a set of port holes which are enclosed by the annular sealing part but may comprise further port holes outside the annular sealing part. The annular sealing part and the two opposing corrugated heat transfer plates create a flow channel in-between themselves. The annular sealing part is made to surround at least two of the ports which are brought in fluid communication with each other via the flow channel between the heat transfer plates. At least one of the heat transfer plates comprises annular groove being arranged to accommodate an annular sealing part and an attachment structure having a plate attachment surface arranged to attach by the adhesive to the gasket attachment surface of the attachment part. The attachment part is connected to an inside of the annular sealing part and extending in an inwards direction relative to the annular sealing part meaning that the attachment part is projecting from the annular sealing part towards an interior of the circumference defined by the annular sealing part. The attachment part thus extends into the flow path defined between the set of port holes. The attachment part should thus not be projecting towards an outer edge of the heat transfer plate or towards an edge of a port hole of the heat transfer plate. The set of port holes is understood to mean at least two port holes.

The attachment part being connected to an inside of the annular sealing part at a first point and extending in an inwards direction relative to the annular sealing part, the attachment part extending less than 1/2 of the distance between the first point and a second point located on the inside of the annular sealing part opposite the first point, preferably less than 1/3, more preferably less than 1/4. The primary objective of the attachment part is to fixate the annular sealing part and not to guide the flow and therefore it must not extend very far into the area enclosed by the annular sealing part.

The gasket attachment surface is generally parallel to the above-mentioned imagined sealing plane and towards a corresponding plate attachment surface of the corrugated heat transfer plate. The adhesive can be of any suitable type, for example a glue or an adhesive agent such as e.g., silicon, or a double -sided adhesive tape. The attachment part is generally adhered to only one of the opposing heat transfer plates for remaining in place when the opposing heat transfer plates are separated from each other due to installation or maintenance.

Having the attachment part projecting on the inside of the annular sealing part means that the flow on the outside of the annular sealing part is undisturbed. The outside of the annular sealing part may thus be free from any attachment parts or outwardly projecting members. It also means that the attachment part may be positioned such that it may influence the flow on the inside of the annular sealing part. It may be advantageous in case it is desired to guide the flow on the inside of the annular sealing part in a particular direction while the flow on the outside of the annular sealing part should remain undisturbed.

According to a further embodiment of the first aspect, the annular sealing part defining a first thickness between parallel lower and upper sealing planes and the attachment part defining a second thickness between parallel lower and upper attachment planes, the parallel lower and upper attachment planes being parallel with the lower and upper sealing planes and the second thickness being different from the first thickness, preferably the second thickness being smaller than the first thickness.

The lower sealing plane is the imagined plane at which the annular sealing part is intended to seal against the annular groove of the heat transfer plate. The upper sealing plane is the extreme plane of the sealing part, but the sealing part is compressed when the plate package is assembled. The first thickness thus corresponds to the extreme extension of the annular sealing part in a direction perpendicular to the sealing plane. The lower attachment plane is the imagined plane at which the attachment part is intended to contact against the attachment surface of one of the heat transfers plates. The upper attachment plane is the imagined plane at the extreme point of the attachment part located opposite the lower attachment plane. The second thickness thus corresponds to the extreme extension of the attachment part in a direction perpendicular to the sealing plane.

The thickness of the attachment part may be different than the thickness of the annular sealing part as it must not be sealing and even if it is sealing it must not be sealing in the same plane as the annular sealing part. The attachment part may preferably have a smaller thickness than the annular sealing part as it must not be establishing a flow channel and may be as thin as structurally possible while having sufficient thickness for serving the purpose of holding the gasket arrangement in place. According to a further embodiment of the first aspect, the lower and upper attachments planes are arranged between the lower and upper sealing planes or the lower attachment plane coincides with the lower sealing plane or the upper attachment plane coincides with the upper sealing plane or the lower sealing plane being arranged between the lower and upper attachments planes or the upper sealing plane being arranged between the lower and upper attachments planes. Such designs may enable an optimized engagement between the attachment part and the corresponding attachment surface of the heat transfer plate. The width and/or thickness, of the attachment part is preferably different from the width and/or thickness of the annular sealing part adjacent the attachment part. In particular, having the lower and upper attachments planes arranged between the lower and upper sealing planes allows a better support for the gasket in the gasket groove. This may allow for higher pressures. Additionally, the channel on the rear side of the plate can also be kept intact, allowing a flow close to the gasket which may counteract fouling.

According to a further embodiment of the first aspect, the annular sealing part defines a specific width between an outer edge of the annular sealing part and an inner edge of the annular sealing part, the attachment part forms a tab or a loop extending between the annular sealing part and an end point a specific distance from the annular sealing part, wherein the specific distance is less than thrice the specific width, preferably less than twice the specific width, more preferably less or equal to the specific width.

The attachment part can extend only a small distance into the flow path between the set of port holes for influencing the flow as little as possible while achieving a sufficiently large attachment surface for fixating the attachment part. The attachment part can be a loop which encloses a part of the heat transfer plate at the inside of the annular sealing part. It can alternatively be a tap which projects inwardly, preferably straight, and a small distance defined above relative to the annular sealing part.

According to a further embodiment of the first aspect, the width of the attachment part is different from the width of the specific width.

The width of the attachment part is defined as the extension of the attachment part in the attachment plane and perpendicular to the projecting direction of the attachment part. The width of the attachment part may be wider than the annular sealing part for increasing the attachment surface for fixating the attachment part while decreasing the specific distance of the attachment part. The width of the attachment part may alternatively be smaller than the annular sealing part if the attachment surface can remain sufficiently large to maintain a sufficient fixation of the gasket arrangement.

According to a further embodiment of the first aspect, the annular sealing part extends along a straight line at the location of the attachment part, preferably the attachment part extends in an oblique angle relative to the extension of the annular sealing part at the attachment part.

The attachment part can be located at a position where the annular sealing part does not bend since the purpose of the attachment part is to be adhered to one of the heat transfer plates for holding it in place and not primarily to guide or stabilize the annular sealing part. The attachment part can preferably be extending in an oblique angle for aligning with the corrugations of the heat transfer plate which typically are extending in an oblique angle for forming a cross pattern when two heat exchanging plates are position juxtaposed to each other. The attachment structure may thus be aligned with a groove or a valley of the corrugation pattern of the heat transfer plate. In this way the influence on the corrugated pattern will be reduced, thereby reducing the influence on the attachment structure on the flow. According to a further embodiment of the first aspect, the attachment surface is flat or defining a plurality of corrugations, the attachment surface being parallel with or defining an angle relative to a plane of extension of the attachment part.

The attachment surface is preferably flat for defining a well-defined surface for the adhesive and being able to distribute the adhesive evenly over the compete attachment surface. The attachment surface may however define a plurality of small corrugations for better accommodating surplus adhesive. The attachment surface may be defining an angle relative to a plane of extension of the attachment for increasing the surface area relative to the extension of the attachment part. In this way the extension of the attachment part may be shorter while maintaining the same surface area which allows the opposing plates to contact and support each other closer to the gasket groove. A shorter attachment part may also cause less disturbance on the flow.

The above object is in a second aspect realized by a corrugated heat transfer plate comprising a set of port holes and a gasket groove, the gasket groove comprising: an annular groove being arranged to accommodate an annular sealing part of a gasket arrangement, enclosing the set of portholes of the heat transfer plate and defining a flow path between the port holes of the set of port holes, and an attachment structure connected to an inside of the annular groove and extending in an inwards direction relative to the annular groove, the attachment structure defining a plate attachment surface arranged to attach by an adhesive to a corresponding gasket attachment surface of an attachment part of the gasket arrangement.

The heat transfer plate according to the second aspect is preferably used together with the gasket arrangement according to the first aspect. The heat transfer plate comprises an annular groove being arranged to accommodate an annular sealing part and an attachment structure having a plate attachment surface arranged to attach by the adhesive to the gasket attachment surface of an attachment part. The heat transfer plate is corrugated to increase the heat transfer. The attachment structure projects from an inside of the annular groove and should thus not be projecting towards an outer edge of the heat transfer plate or towards an edge of a port hole of the heat transfer plate.

The attachment structure being connected to an inside of the annular groove at a first point and extending in an inwards direction relative to the annular groove, the attachment structure extending less than 1/2 of the distance between the first point and a second point located on the inside of the annular groove opposite the first point, preferably less than 1/3, more preferably less than ¼. The primary objective of the attachment structure is to fixate the annular sealing part and not to guide the flow and therefore it must not extend very far into the area enclosed by the annular sealing part.

The heat transfer plate according to the second aspect may include any of the features of the gasket arrangement according to the first aspect.

According to a further embodiment of the second aspect, the heat transfer plate may comprise an outer annular gasket groove enclosing the annular gasket groove, the outer gasket groove preferably being located adjacent an outer edge of the corrugated heat transfer plate.

The attachment structure is preferably located on the inside of an inner gasket groove which is enclosed by an outer annular gasket groove and allowing flow outside the inner annular gasket groove and inside the outer annular gasket groove which is then not disturbed by the attachment structure.

According to a further embodiment of the second aspect the plate attachment surface coincides with the annular gasket groove or the plate attachment surface defining a smaller press depth than the annular gasket groove or the plate attachment surface defining a larger press depth than the annular gasket groove. This is so that the attachment part preferably can define a different thickness than the annular sealing part. The above object is in a third aspect realized by a heat exchanger comprising a plate package comprising a gasket arrangement located between a pair of opposing corrugated heat transfer plates, each corrugated heat transfer plate comprising a set of port holes and a gasket groove, the gasket groove comprising: an annular groove enclosing the set of portholes of the heat transfer plate and defining a flow path between the port holes of the set of port holes, and an attachment structure connected to an inside of the annular groove and extending in an inwards direction relative to the annular groove, the attachment structure defining a plate attachment surface, the gasket arrangement comprising: an annular sealing part extending along the annular groove of the gasket groove and being arranged to enclose the set of portholes of the heat transfer plates, and an attachment part connected to an inside of the annular sealing part and extending in an inwards direction relative to the annular sealing part, the attachment part defining a gasket attachment surface attached by an adhesive to the plate attachment surface of the attachment structure of one of the heat transfer plates.

The heat exchanger according to the third aspect comprising a gasket arrangement according to the first aspect, a pair of opposing heat transfer plates according to the second aspect and an adhesive applied between the fastening attachment portion of the gasket arrangement and the fastening structure portion of one of the heat transfer plates. The attachment structure extending less than 1/2 of the distance between the first point at which the attachment structure connected to an inside of the annular groove and a second point located on the inside of the annular groove opposite the first point, preferably less than 1/3, more preferably less than 1/4. The attachment part extending along the attachment structure.

The attachment part can contact both heat transfer plates. This may be beneficial in case a guiding of the flow is desired. However, the attachment part may alternatively define a gap to the upper plate and allow a flow between the attachment and the upper plate.

According to a further embodiment of the third aspect, the attachment surface of the attachment structure coincides with a valley of one of the heat transfer plates. In this way there is no need for a separate attachment surface as the valley can act both as a contact point and support surface for the opposing plates as well as an attachment surface for the attachment structure.

The above object is in a fourth aspect realized by a method of assembling a plate package for a plate heat exchanger by providing: a gasket arrangement according to the first aspect, a pair of heat transfer plates according to the second aspect, and an adhesive, the method comprising the step of: applying the adhesive on the plate attachment surface and/or on the gasket attachment surface, and arranging the gasket arrangement between the pair of opposing corrugated heat transfer plates, thereby forming the plate package.

The above method can be used for producing or refurbishing a heat exchanger according to the third aspect. BRIEF DESCRIPTION OF THE DRAWINGS

FIG 1 A is a front view of a heat transfer plate for freshwater production.

FIG 1B is a front view of the plate of FIG 1A having a gasket.

FIG 2A is a front view of a part of the plate of FIG 1 B.

FIG 2B is a perspective view of a part of the plate of FIG 1 A.

FIG 2C is a perspective view of a part of the plate and gasket of FIG 1 B.

FIG 3A is a side view of a plate and gasket arrangement.

FIG 3B is a side view of an alternative plate and gasket arrangement.

FIG 3C is a side view of a further alternative plate and gasket arrangement.

FIG 3D is a side view of a yet further alternative plate and gasket arrangement. FIG 3E is a side view of a plate and gasket arrangement similar to FIG 3A.

FIG 3F is a side view of a further arrangement similar to FIG 3A.

FIG 3G is side view of a yet further arrangement similar to FIG 3A.

FIG 3H is a side view of a plate and gasket arrangement similar to FIG 3G.

FIG 4A is a front view of a heat transfer plate for a heat exchanger.

FIG 4B is a front view of the plate of FIG 4A having a gasket.

FIG 5A is a perspective view of a part of the plate of FIG 4A.

FIG 5B is a perspective view of a part of the gasket arrangement of FIG 4B.

FIG 5C is perspective view of a part of the plate and gasket of FIG 4B.

FIG 6A is a front view of an alternative heat transfer plate for a heat exchanger. FIG 6B is a front view of the alternative plate of FIG 6A having a gasket.

FIG 7A is a perspective view of a part of the alternative plate of FIG 6A.

FIG 7B is a perspective view of a part of the gasket arrangement of FIG 6B.

FIG 7C is perspective view of a part of the alternativ plate and gasket of FIG 6B.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG 1 A is a front view of a heat transfer plate 10 for freshwater production. The heat transfer plate 10 is made of metal such as stainless steel, or more preferably titanium, and comprises an evaporation section 12, a separation section 14, and a condensation section 16.

The evaporation section 12 is corrugated to form a cross corrugated pattern together with an opposing plate which is turned 180 degrees and enclosed by a first inner annular groove 18. The evaporation section 12 comprises a first guide groove 20, a heating fluid outlet 22 and a heating fluid inlet 24 for circulating a heating fluid. The evaporation section 12 further comprises two opposite feed inlets 26 for introducing sea water on the opposite side of the heat transfer plate 10 to be evaporated by the heating fluid.

The separation section 14 is corrugated such that corrugations of opposing plates fall into each other for removing any droplets from the evaporated sea water. The separation section 14 includes two opposite passages 28 for transporting evaporated feed into the separation section 14 and two pairs of opposite passages 30 for transporting evaporated feed from the separation section 14 into the condensation section 16.

The condensation section 16 is corrugated to form a cross corrugated pattern together with an opposing plate which is turned 180 degrees and enclosed by a second inner annular groove 32. The condensation section 16 comprises a second guide groove 34, a cooling fluid inlet 36 and a cooling fluid outlet 38 for circulating a cooling fluid. The condensation section 16 further comprises a freshwater outlet 40 for discharging fresh water which is condensed on the opposite side of the heat transfer plate 10.

The heat transfer plate 10 has two opposite brine outlets 44 at the bottom of the plate for removing any unevaporated part of the feed. The heat transfer plate 10 is enclosed by an outer annular gasket groove 42. The heat transfer plate 10 further comprises attachment structures 46 which will be discussed in detail further below. The attachment structures 46 extend from respective attachment points on the inner side of the first inner annular groove 18 towards opposite points on the first inner annular groove 18 on the opposite side, however, only a small distance (less than 1/2 the distance to the opposite points on the first inner annular groove 18) when compared to the first guide groove 20 (which extends more that 1/2 the distance to the opposite point on the first inner annular groove 18).

FIG 1B is a front view of the heat transfer plate 10 of FIG 1A having a gasket arrangement made up of annular sealing parts 18’ 32’ 42’, guiding parts 20’ 34’ and attachment parts 46’. The gasket arrangement is made of a flexible material such as rubber. A first inner annular sealing part 18’ is located in the first inner annular gasket grove. A first guiding part 20’ is located in the first guide groove. A second inner annular sealing part 32’ is located in the second inner annular groove. A second guiding part 34’ is located in the second guide groove. An outer annular sealing part 42’ is located in an outer annular gasket groove 42. Attachment parts 46’ are located in and along the attachment structures. The attachment parts 46’ extend from respective attachment points on the inner side of the first inner annular sealing part 18’ towards opposite points on the first inner annular sealing part 18’ on the opposite side, however, only a small distance (less than 1/2 the distance to the opposite points on the first inner annular groove 18) when compared to the first guiding part 20’ (which extends more than 1/2 the distance to the opposite point on the first annular sealing part 18’)

The unevaporated part of the feed which is separated by the separation section 14 falls onto the outer side of the first inner annular sealing part 18’ and is guided between the first inner annular sealing part 18’ and the outer annular sealing part 42’ to the brine outlets 44.

FIG 2A is a front view of a part of the evaporation section 12 of the heat transfer plate 10 of FIG 1 B. The two attachment parts 46’ visible here are projecting from the inner side of the first inner annular sealing part 18’ into the evaporation section 12 and the flow path (illustrated by the dashed arrow) defined between the heating water inlet 24 and the heating water outlet 22. The attachment parts 46’ have an attachment surface (not visible) which is fastened to the underlying attachment structure (covered by the attachment part) of the heat transfer plate 10 by means of adhesive such as liquid adhesive, solid adhesive or adhesive double-sided tape. The attachment parts 46’ hold the first inner annular sealing part 18’ in place when the plate package is open for assembly or repair at which time the opposing heat transfer plates do not fixate the first inner annular sealing part and may optionally be used for directing the flow in a specific direction (as illustrated by the dashed arrow) so that the flow covers the complete evaporation section 12. However, having the attachment part directed in the same direction as the adjacent ridges and valleys may reduce the influence on the corrugated pattern and thereby eliminate any effect of the attachment part on the flow. The outer side of the inner annular sealing part 18’ is free from any attachment parts for being free from obstructions which may hinder the flow of the unevaporated part of the feed on the outer side of the first inner annular sealing part 18’.

The evaporation section 12 is corrugated and defines a corrugation pattern of alternating ridges 48 and valleys 50. The attachment structure (covered by the attachment part 46’) is preferably coinciding with an existing ridge 48 or valley 50 of the corrugation pattern of the heat exchanging plate 10. This typically means that the attachment part 46’ defines an oblique angle relative to the annular sealing part 18’ at the location of the attachment part 46’. The attachment surface (covered by the attachment part 46’) of the heat transfer plate 10 typically define a different press depth than the coinciding ridge 48 or valley 50.

The first inner annular sealing part 18’ includes an optional short stabilizing part 52 extending a short distance into a port gasket groove 54. The port gasket groove 54 is used by a port sealing on the opposite side of the heat transfer plate 10 to encircle the heating fluid inlet 24 and a heating fluid outlet 22. The short stabilizing part 52 is located at a bend of the first inner annular sealing part 18’ and is not fixated by any adhesive means but merely used for stabilizing and guiding purposes at the junction between the first inner annular groove located at a bend of the first inner annular sealing part 18’.

FIG 2B is a perspective view of a part of the evaporation section 12 of the heat transfer plate 10 of FIG 1A, without the gasket arrangement. The heat transfer plate 10 comprises alternating gasket guiding elevations 56 and gasket guiding depressions 58 on the outer side of the first inner annular groove 18 and alternating ridges 48 and valleys 50 on the inner side of the first inner annular groove 18 for holding the first inner annular sealing part in place. The attachment structure 46 defines an attachment surface for attaching by adhesive means to the corresponding attachment part (not shown) of the gasket arrangement. The attachment structure 46 is here aligned with the ridges 48 for not disturbing the corrugation pattern of the evaporation section 12

FIG 2C is a perspective view of a part of the heat transfer plate 10 and gasket of FIG 1 B. The attachment part 46’ projects inwardly from the annular sealing part 18 and defines a flat contact surface (not visible) being adhered to a corresponding flat contact surface 46” of the attachment structure 46 of the heat transfer plate 10 for keeping the annular sealing part 18 in place when the plate package is open. The attachment part 46’ extends in an oblique angle aligned with the ridge 48 from a straight part of the annular sealing part 18’. The attachment part 46’ defines a flat upper surface 46”’ which preferably contacts an opposing contact surface (not shown) of an opposing heat transfer plate.

FIG 3A is a side view of a heat transfer plate 10 (where a ridge 48, a valley 50, a protrusion 56 and depression 58 are shown overlaying each other) and gasket arrangement comprising an annular sealing part 18’ and an attachment part 46’. The thickness direction of the gasket arrangement is shown by the arrow T. The attachment part 46 defining an attachment surface being adhered to a corresponding attachment surface 46” of the attachment structure 46 of the heat transfer plate 10. The annular sealing part 18’ positioned in the annular gasket groove 18 and defines a lower sealing plane S1 at the annular gasket groove 18 and an upper sealing plane S2 at an imaginary position of an opposing heat transfer plate. In the present embodiment the attachment part 46’ defines a lower attachment plane A1 at the attachment surface 46” which is coinciding with the lower sealing plane S1 and an upper attachment plane A2 located between a ridge 48 and an upper sealing plane S2.

FIG 3B is a side view of an alternative heat transfer plate 10 and gasket arrangement. In the present embodiment the attachment part 46’ defines a sloping attachment surface between an attachment plane A1 which is coinciding with the lower sealing plane S1 and an upper attachment plane A2 located between a ridge 48 and an upper sealing plane S2.

FIG 3C is a side view of a further alternative heat transfer plate 10 and gasket arrangement. In the present embodiment the attachment part 46’ defines a lower attachment plane A1 at the attachment surface 46” which is not coinciding with the lower sealing plane S1 but located between the lower sealing plane S1 and an upper attachment plane A2 which is located between a ridge 48 and an upper sealing plane S2.

FIG 3D is a side view of a yet further alternative heat transfer plate 10 and gasket arrangement. In the present embodiment the attachment part 46’ defines a lower attachment plane A1 at the attachment surface 46” which is coinciding with the lower sealing plane S1 and a valley 50 and an upper attachment plane A2 located between a ridge 48 and an upper sealing plane S2.

FIG 3E is a side view of a plate and gasket arrangement similar to FIG 3A except that the attachment surface 46” defines a plurality of small corrugations for being able to accommodate any possible excessive adhesive better.

FIG 3F is a side view of a further arrangement similar to FIG 3A, except that both a ridge 48 and a valley 50 has been modified to define the attachment surface 46” of the attachment structure 46. This may be used when it is desired to make the attachment surface 46” and the corresponding attachment part 46’ wider than the width of a single ridge 48 or valley 50.

FIG 3G is side view of a yet further arrangement similar to FIG 3A, except that the lower attachment plane A1 is located below the lower sealing plane S1.

FIG 3H is a side view of a plate and gasket arrangement similar to FIG 3G, except that the attachment surface 46” of the attachment structure 46 coincides with a valley 50 instead of a ridge 48.

FIG 4A is a front view of a corrugated heat transfer plate 60 for a heat exchanger. The heat transfer plate 60 comprises four port holes 62A-D (not cut out in the figure). The heat transfer plate 60 further comprises an annular groove 42 which encloses the heat transfer plate 60 and defines flow passages between portholes 62A and 62B, and, between portholes 62C and 62D, respectively. The heat transfer plate 60 further comprises a plurality of attachment structures 46 connected to an inside of the annular groove 42. The attachment structures 46 extend from respective attachment points on the inner side of the annular groove 42 towards opposite points having attachment structures 46 on the annular groove 42 on the opposite side, however, only a small distance (less than 1/2 the distance to the opposite points on the annular groove 42).

FIG 4B is a front view of the plate of FIG 4A having a gasket arrangement. The gasket arrangement comprising an annular sealing part 42’ located in the annular groove of the heat transfer plate 60 and defining a flow passage between portholes 62A and 62B but prevents fluid communication with any of the two other port holes 62C and 62D. As a side note, another annular sealing part (not shown) on the opposite side of the heat transfer plate 60 defines a flow passage between portholes 62C and 62D but prevents fluid communication with any of the two other port holes 62A and 62B. In the heat exchanger several heat transfer plates 60 are stacked whereby every second heat transfer plate is turned 180 degrees, having an annular sealing parts 42’ between themselves, whereby every second annular sealing part 42’ is configured to form a flow channel between portholes 62A and 62B but preventing fluid communication with any of the two other port holes 62C and 62D and every other annular sealing parts 42’ is configured to form a flow channel between portholes 62C and 62D but preventing fluid communication with any of the two other port holes 62A and 62B.

The gasket arrangement further comprising a plurality attachment parts 46’ each located at a respective attachment structures 46 and being connected to an inside of the annular sealing part 42’. The attachment parts 46’ are located close to an outer edge of heat transfer plate 60 but extending inwardly relative to the annular sealing part 42’. The attachment parts 46’ are located spaced apart from the port holes 62A-D. The attachment parts 46’ extend from respective attachment points on the inner side of the first inner annular sealing part 42’ towards opposite points having attachment parts 46’ on the first inner annular sealing part 42’ on the opposite side, however, only a small distance (less than 1/2 the distance to the opposite points on the first inner annular sealing part 42’).

FIG 5A is a perspective view of a part of the heat transfer plate 60 of FIG 4A. The annular groove 42 of the heat transfer plate 60 is located between alternating elevations 56 and depressions 58 on one side adjacent the edge of the heat transfer plate 60 and ridges 48 and valleys 50 located on the opposite side of the annular groove 42 inside the heat transfer area of the heat transfer plate 60. The attachment part 46 projects inwardly into the heat transfer area and into the flow path. The attachment part 46 defines an attachment surface 46” intended to be adhered to a corresponding surface of an attachment part of an annular gasket part. In this way clips and other similar means can be avoided close to the edge of the heat transfer plate 60. FIG 5B is a perspective view of a part of the gasket arrangement of FIG 4B. The gasket arrangement comprises the annular sealing part 42’ and the attachment part 46’.

FIG 5C is perspective view of a part of the heat transfer plate 60 and gasket arrangement of FIG 4B. The attachment part 46’ of the gasket arrangement and the corresponding attachment structure 46 of the heat transfer plate 60 define a with being greater than the width of the annular sealing part 42 ^' and the corresponding annular groove 42. The width of the attachment part 46’ and the corresponding attachment structure 46 is also greater than the width of a single ridge 48 or a single valley. In this way the attachment part must not extend far into the flow path while still allowing a sufficient attachment surface for the adhesive.

FIG 6A is a front view of a corrugated heat transfer plate 60 for a heat exchanger. The present heat transfer plate 60 is identical to the heat transfer plate of FIG 4A, except that the plurality of attachment structures 46 extend in an oblique angle relative to the extension of the annular groove 42 at the attachment part 46.

FIG 6B is a front view of the heat transfer plate of FIG 6A having a gasket arrangement. The gasket arrangement is identical to the gasket arrangement of heat transfer plate of FIG 4B, except that the attachment parts 46’ extend in an oblique angle relative to the extension of the sealing part 42’ at the attachment part 46’.

FIG 7A is a perspective view of a part of the heat transfer plate 60 of FIG 4A. The attachment structure 46 extends from the annular groove 42 in the same direction as the adjacent obliquely extending ridges 48 and valleys 50 of the heat transfer plate 60. In this way the influence on the corrugated pattern will be reduced compared to having an attachment structure extending at a right angle relative to the extension of the annular groove. FIG 7B is a perspective view of a part of the gasket arrangement of FIG 6B. The attachment part 46’ extends from the sealing part 42’ in the same direction as the adjacent ridges 48 and valleys 50 of the heat transfer plate 60 to conform with the attachment structure of FIG 7A.

FIG 7C is perspective view of a part of the heat transfer plate 60 and gasket arrangement of FIG 6B. The number of attachment parts, structures, bridges, bridge receiving portions, etc., in the above-described embodiments are just exemplary and can be varied.

The present invention could be used in connection with other types of heat transfer plates than the above described one. Such other plate types could be made of other materials than stainless steel and titanium, be provided with a gasket groove of an alternative design, be provided with another pattern or another port hole design. A corresponding reasoning is valid for the gasket arrangement.

The present invention could be used in connection with other types of plate heat exchangers than purely gasketed ones, e.g., plate heat exchangers comprising cassettes of permanently joined heat transfer plates. It should be stressed that the attributes first and second is used herein just to distinguish between species of the same kind and not to express any kind of mutual order between the species.

It should be stressed that a description of details not relevant to the present invention has been omitted and that the figures are just schematic and not drawn according to scale. It should also be said that some of the figures have been more simplified than others. Therefore, some components may be illustrated in one figure but left out on another figure.