Double plate heat exchanger

Abstract

The present invention relates to a plate heat exchanger comprising a stack of plate elements, each plate element being a double-walled structure comprising a first heat transfer plate and a second heat transfer plate, each heat transfer plate comprising a central heat exchange section provided with a surface pattern adapted to have the surface pattern of the first heat transfer plate of one plate element contact the surface pattern of the second heat transfer plate of an adjacent plate element, thereby forming a first flow path for a first fluid on one side of the plate element and a second flow path for a second fluid on a second side of the plate element, wherein the plate elements are formed with openings in an opening area, wherein the first heat transfer plate in the opening area is formed with a closed protrusion protruding in a first direction and in the same opening area is formed with an open protrusion, the open protrusion being formed in a second direction opposite to the first direction, such that the closed protrusion and the open protrusion together define a first leakage cavity.

Description

TECHNICAL FIELD

[0001] The present invention relates to plate heat exchangers of the type having double plates. More specifically, the present invention relates to double plate heat exchangers in which a leakage can be detected more easily than in similar double plate heat exchangers of the prior art. BACKGROUND

[0002] Plate heat exchangers exchange heat between two or more fluids. In most plate heat exchangers, a plurality of stacked plate elements separate the fluids, each plate element having a central heat transfer portion and a surrounding edge portion. It is sometimes necessary to pay particular attention to avoid that one heat exchange fluid leaks into the flow path of another heat exchange fluid. This occurs, for example, in heat exchangers used for heating or cooling of potable fluids using non-potable fluids, in heat exchangers used for handling critical fluids, and in heat exchangers in which mixing of the two fluids would result in an undesired chemical reaction. In these cases, it is common to use heat exchangers of the double wall type. In double wall heat exchangers, the plate elements separating the heat exchange fluids each comprise two plates which are joined together. For brazed heat exchangers, it is necessary to avoid brazing of some areas.

[0003] In order to be able to detect a leakage of one of the plates, the plates are usually joined together so that the leaking fluid is allowed to flow between the plates towards the edge portion of the plate element, for example, to a location where it can be detected. A quick detection of a leakage requires that the plates are arranged at a sufficient distance from each other to allow the leaking fluid to easily flow towards the detection location. On the other hand, in order to provide sufficient efficiency in the heat transfer between the heat exchange fluids, it is desirable to arrange the plates as close to each other as possible. Therefore, various different attempts have previously been made to design double wall heat exchangers taking both of these requirements into account. SUMMARY

[0004] The object of the present invention is solved in accordance with the features presented in the claims.

[0005] This includes introducing a plate heat exchanger comprising a stack of plate elements, each plate element being a double-walled structure comprising a first heat transfer plate and a second heat transfer plate, each heat transfer plate comprising a central heat exchange section provided with a surface pattern, the surface pattern being adapted to have the surface pattern of the first heat transfer plate of one plate element contact the surface pattern of the second heat transfer plate of an adjacent plate element, thereby forming a first flow path for a first fluid on one side of the plate element and a second flow path for a second fluid on a second side of the plate element, wherein the plate element is formed with an opening in an opening area, wherein the first heat transfer plate is formed with a closed protrusion protruding in a first direction in the opening area, and the first heat transfer plate is formed with an open protrusion in the same opening area, the open protrusion being formed in a second direction opposite the first direction, such that the closed protrusion and the open protrusion together define a first leakage cavity.

[0006] The open protrusion can be adapted to allow fluid to pass between the respective opening and the respective flow path when connected to an open protrusion of an adjacent plate element, and wherein the closed protrusion is adapted to close off fluid and seal the respective opening with respect to the respective flow path.

[0007] A plurality of open protrusions can be positioned around the entire perimeter of the respective opening, and a single closed protrusion can surround the respective opening.

[0008] A first fixation portion and a second fixation portion can be positioned at opposite sides of the relevant opening, thereby fixing the first heat transfer plate and the second heat transfer plate of the plate element together.

[0009] The closed protrusion can be communicated to a drain channel formed to fluidically communicate the closed protrusion to an exterior of the plate heat exchanger. The drain channel can be formed as a protrusion formed in the same first direction as the closed protrusion.

[0010] A recess can be formed in the closed protrusion, and wherein the recess protrudes in a second direction opposite the closed protrusion, and protrudes into the first leakage cavity.

[0011] The closed protrusion can be connected to a closed protrusion of a heat transfer plate of a connected adjacent plate element, the recess defining a second leakage cavity.

[0012] The second leakage cavity can be positioned between respective third and fourth fixation portions fixing a heat transfer plate to a heat transfer plate of an adjacent plate element.

[0013] An opening can be formed in a plate wall shared by the closed protrusion and the recess, thereby forming a fluid communication between the first leakage cavity and the second leakage cavity. Attached Figure Description

[0014] Figure 1 This is a general diagram illustrating the principle of a plate heat exchanger.

[0015] Figure 2 This is a side view of a double-plate heat exchanger according to the present invention.

[0016] Figure 3 This is a top view of a portion of the heat transfer plate according to the present invention.

[0017] Figure 4 This is a side view of a portion of a double-plate heat exchanger according to the present invention. Detailed Implementation

[0018] It should be understood that while the detailed description and specific examples indicate embodiments of the invention, they are given by way of illustration only, as various different variations and modifications from the detailed description will become apparent to those skilled in the art.

[0019] Figure 1 and Figure 2 The diagram illustrates a heat exchanger 1 formed by plate elements 2 connected to adjacent plate elements 2. Each plate element 2 is formed with openings 3a, 3b, 3c, 3b and a heat exchange portion 40 having a surface pattern 45. When stacked, the connected surface patterns 45 of adjacent plate elements 2 form flow paths A and B at corresponding opposing surfaces of the plate elements 2. Furthermore, the openings 3a, 3b, 3c, 3b are aligned to form a first set of openings 3a, 3d and a second set of openings 3b, 3c, respectively. The first set of openings 3a, 3d defines the inlet and outlet of the first flow path A, and the second set of openings 3b, 3c defines the inlet 3b and outlet 3c of the second flow path B. The first set of openings 3a, 3d and the first flow path A are sealed relative to the second set of openings 3b, 3c and the second flow path B, thereby allowing fluid to pass through the heat exchanger without contacting and mixing the two fluids. This heat exchanger is suitable for transferring heat from a hotter fluid to a colder fluid in a fluid flowing along flow paths A and B on plate element 2.

[0020] Plate element 2 is a double-walled structure comprising a first heat transfer plate 10 and a second heat transfer plate 20, each heat transfer plate including a central heat exchange portion 40 having a surface pattern 45. The first heat transfer plate 10 and the second heat transfer plate 20 are connected over a large portion of their extensions, such as at the central heat exchange portion 40. If one heat transfer plate fails, for example due to the formation of a crack, the other heat transfer plate will ensure that fluid does not leak between the first flow path A and the second flow path B.

[0021] Figure 3Portions of the heat transfer plates 10, 20 around the two openings 3a, 3b formed in the opening areas 30a, 30b are shown. The opening areas 30a, 30b, 30c, 30d are generally formed by substantially flat portions around the openings 3a, 3b, 3c, 3d. The drawing shows a protrusion 50 formed in at least one of the opening areas 30a, which protrudes in a first direction. The protrusion 50 can completely encircle the respective opening 3a.

[0022] The protrusion 50 can have a substantially flat top surface adapted to contact a similar surface of an adjacent heat transfer plate 10, 20.

[0023] A recess 55 can be formed in the top surface of the protrusion 50, which recess 55 protrudes in a second direction opposite the first direction. The recess 55 can be formed at the entire periphery of the protrusion 50.

[0024] The protrusion 50 in the illustrated embodiment is connected to a drain 60 formed to fluidly connect the protrusion 50 to the outside of the heat exchanger 1, such as to a side of the heat exchanger 1. In the illustrated embodiment, the drain 60 is formed as a protrusion or shape in the heat transfer plates 10, 20 in the opening area 30a, thereby connecting the protrusion 50 to an edge of the heat transfer plates 10, 20. The protrusion or shape forming the drain 60 can be formed in the same first direction as the protrusion 50, but can be lower than the protrusion 50, such that the protrusion or shape forming the drain 60 does not contact any adjacent plate elements 2.

[0025] At least one of the other opening areas 30b can be formed with protrusions 65 formed at a distance from each other, or at least having openings allowing fluid to pass between the respective openings 3a, 3b, 3c, 3d and the respective flow paths A, B. Such protrusions 65 are in the following referred to as “open protrusions” 65, and such protrusions 65 can be positioned around the entire periphery of the respective openings 3b.

[0026] Figure 4 A partial cross-section of the heat exchanger 1 of Figure 2 is illustrated, showing the openings 3a, 3b, 3c, 3d of a plurality of stacked plate elements 2.

[0027] The opening areas 30a, 30b, 30c, 30d can form substantially flat sections extending parallel to the extension of the respective heat exchanger plates 10, 20. In at least one of the opening areas 30a, the first heat transfer plate 10 and the second heat transfer plate 20 of the plate element 2 in the embodiment are formed with protrusions 50 protruding in opposite directions relative to each other in the opening areas 30a, 30b, 30c, 30d.

[0028] In the illustration, the first flow path A is sealed with respect to the respective opening 3a, 3b, 3c, 3d by the protrusion 50 of the heat transfer plate 10, 20 contacting the adjacent plate element 2, and thus the protrusion 50 can be referred to as a “closing protrusion” 50. The closing protrusion 50 can close the flow path at the entire periphery of the respective opening 3a, 3b, 3c, 3d.

[0029] Figure 4 The second flow path B in the opening 3a, 3b, 3c, 3d is open, meaning that the respective opening 3a, 3b, 3c, 3d operates as a fluid inlet or outlet for this second flow path B.

[0030] In the illustrated embodiment, both the first plate 10 and the second plate 20 are formed with such closing protrusions 50, which are adapted to be connected at their top surfaces, which can thus be flat.

[0031] As illustrated, the first plate 10 and the second plate 20 of the plate element 2 in this embodiment do not contact each other, but rather the heat transfer plates 10, 20 of the adjacent plate element 2. This can make the closing protrusion 50 and the open protrusion 65 of the first heat transfer plate 10 contact the closing protrusion 50 and the open protrusion 65, respectively, of the corresponding second heat transfer plate 20. In the same way, the closing protrusion 50 and the open protrusion 65 of the second heat transfer plate 20 contact the closing protrusion 50 and the open protrusion 65, respectively, of the corresponding first heat transfer plate 10.

[0032] The closing protrusion 50 supports the connected respective adjacent plate element 2 in the opening area 30a, 30b, 30c, 30d just as the surface pattern 45 does in the heat exchange portion 40. Also as previously indicated, these closing protrusions 50 also seal the fluid between the respective opening 3a, 3b, 3c, 3d and the respective flow path A, B, e.g. the illustrated first flow path A.

[0033] On both sides of the closing protrusion 50, the first heat transfer plate 10 and the second heat transfer plate 20 of the plate element 2 are connected in the opening area 30a, 30b, 30c, 30d, just as the first heat transfer plate 10 and the second heat transfer plate 20 are, e.g. in the heat exchange portion 40. At these connections, the first heat transfer plate 10 and the second heat transfer plate 20 can be fixed by a first fixation 200 and a second fixation 210 of the periphery at a first radial distance and a second radial distance, respectively, with respect to the respective opening 3a, 3b, 3c, 3d. The fixation can be obtained by fusion welding, brazing, gluing, etc.

[0034] The first 200 and second 210 fixation portions are positioned at opposite sides of the closing protrusion 50 with respect to the openings 3a, 3b, 3c, 3d. The first fixation portion 200 seals against the fluid inside the openings 3a, 3b, 3c, 3d, and the second fixation portion 210 seals between the first 10 and second 20 heat transfer plates of the plate element.

[0035] When the connected first 10 and second 20 heat transfer plates are aligned and connected into a plate element 2, they together define a first leakage cavity 70. If the first 200 or second 210 fixation portions fail to seal, the first leakage cavity 70 will collect the leaking fluid before it mixes with the fluid in the other of the flow paths A, B.

[0036] The open flow path B is ensured by an open protrusion 65, such as a dimple or other shape, at the periphery of the openings 3a, 3b, 3c, 3d.

[0037] In the illustrated embodiment, both the first 10 and second 20 heat transfer plates are formed with such open protrusions 65 adapted to connect at their possibly flat top surfaces. In this way, the open protrusions 65 support the respective plate element 2 in the opening area 30a, 30b, 30c, 30d and at the same time allow fluid into the respective flow path A, B, such as into the illustrated second flow path B.

[0038] In other, not illustrated, embodiments, only one of the first 10 and second 20 heat transfer plates is formed with a closing protrusion 50 and / or an open protrusion 65. In this embodiment, the closing protrusion 50 and / or open protrusion 65 is adapted to contact the possibly flat portion of the opening area 30a, 30b, 30c, 30d of the respective heat transfer plate 10, 20 of the adjacent plate element 2.

[0039] Figure 4 It is shown that the first flow path A is sealed with respect to the respective opening 3a, 3b, 3c, 3d, and the second flow path B is open. The heat exchanger 1 can be formed such that connecting the first flow path A and each set of openings 3b, 3c, respectively, 3a, 3d, comprises a sealed opening area 30a, 30c formed with a closing protrusion 50 and an opening area 30b, 30d formed with an open protrusion 65.

[0040] In the same manner as for the corresponding first leakage cavity 70, the discharge channel 85 can be formed by a protrusion or shape formed in the plate material of the first heat transfer plate 10 and / or the second heat transfer plate 20, protruding in the corresponding same first direction and second direction. Either of the two heat transfer plates 10, 20 is formed with such a protrusion, and thus the discharge channel 85 is formed by the two aligned protrusions or shapes. Alternatively, the protrusion or shape is formed in only one of the heat transfer plates 10, 20, and the discharge channel 85 is formed by aligning the protrusion or shape with a possible flat surface of the other heat transfer plate 10, 20 of the plate element.

[0041] The discharge channel 85 extends from the first leakage cavity 70 to an outer edge of the corresponding heat transfer plate 10, 20, and thus the discharge channel 85 is adapted to discharge leaked fluid within the first leakage cavity 70 to an edge of the heat exchanger 1, and thereby to the outside. The leakage can then be detected visually by viewing the leaked fluid, or by including a leakage sensor.

[0042] In Figure 4 It can also be seen in that the recess 55 in the protrusion 50 of at least one of the first heat transfer plate 10 or the second heat transfer plate 20 is formed, and where the recess 50 protrudes opposite the protrusion 50, and thereby into the first leakage cavity 70. If the closed protrusion 50 of the first heat transfer plate 10 protrudes in the first direction, the recess 55 in the closed protrusion 50 of the first heat transfer plate 10 protrudes in a second direction opposite the first direction. Correspondingly, if the closed protrusion 50 of the second heat transfer plate 20 protrudes in the second direction, the recess 55 of the closed protrusion 50 of the second heat transfer plate 20 protrudes in the first direction. In general, this embodiment illustrates a closed protrusion 50 of the first heat transfer plate 10 formed in a direction opposite the closed protrusion 50 of the second heat transfer plate 20. Correspondingly, the respective recess 55 of the first heat transfer plate 10 and the second heat transfer plate 20 is oriented opposite each other.

[0043] Thus, the recess 55 defines a second leakage cavity 80 of the plate element 2, positioned between the two first leakage cavities 70. In case the second leakage cavity 80 is formed by two connected plate elements 2, the first leakage cavities 70 are formed within the plate elements 2 themselves.

[0044] As described, in the illustrated embodiment, both the first heat transfer plate 10 and the second heat transfer plate 20 of an adjacent plate element 2 are formed with a recess 55 projecting in opposite directions relative to each other, such that when the first heat transfer plate 10 and the second heat transfer plate 20 are aligned they define a first leakage cavity 70. Alternatively, only one of the first heat transfer plate 10 and the connected second heat transfer plate 20 of an adjacent plate element 2 is formed with a recess 55. Then, when the possible flat top surface of the closing protrusion 50 connected to the contacted heat transfer plate 10, 20, a second leakage cavity 80 is formed.

[0045] The second leakage cavity 80 is positioned between a respective third fixation 220 and a fourth fixation 230 of the second heat transfer plate 20 of the adjacent plate element 2 that fix the first heat transfer plate 10. The third fixation 220 and the fourth fixation 230 are obtained, for example, by fusion welding, brazing, gluing, etc.

[0046] The third fixation 220 is at a third radial distance from the opening 3a, 3b, 3c, 3d of the opening area 30a, 30b, 30c, 30d, and the fourth fixation 220 is at a fourth radial distance from the opening 3a, 3b, 3c, 3d of the opening area 30a, 30b, 30c, 30d, and the recess 55 is positioned between the third fixation 220 and the fourth fixation 230.

[0047] The third fixation 220 seals the fluid inside the opening 3a, 3b, 3c, 3d, and the fourth fixation 230 seals the fluid inside the respective first flow path A, B.

[0048] If the third fixation 220 or the fourth fixation 230 fails to seal, the second leakage cavity 80 will collect the leaked fluid before it mixes with the fluid in the other of the flow paths A, B.

[0049] The opening 75 can be positioned to connect the first leakage cavity 70 and the second leakage cavity 80, such as in the recess 55 separating the first leakage cavity 70 from the second leakage cavity 80. The leaked fluid collected in the second leakage cavity 80 will thus be directed to the first leakage cavity 70, and from there through the drain 60 to the outside of the heat exchanger for detection.

[0050] The plate elements 2 can be formed by the first heat transfer plates 10 and the second heat transfer plates 20, respectively, such that, when stacked to the heat exchanger 1, if, for example, the first heat transfer plates 10 are formed with closed protrusions 50 in the opening areas 30a, 30b, 30c, 30d, the closed protrusions 50 are connected to the closed protrusions 50 of the second heat transfer plates 20 of the adjacent plate elements 2. In this case, in the same opening areas 30a, 30b, 30c, 30d, the second heat transfer plates 20 are formed with open protrusions 65, which are connected to the open protrusions 65 of the first heat transfer plates 10 of the adjacent plate elements 2 on the opposite side.

[0051] Correspondingly, if, for example, the first heat transfer plates 10 are formed with open protrusions 65 in the opening areas 30a, 30b, 30c, 30d, the open protrusions 65 are connected to the open protrusions 65 of the second heat transfer plates 20 of the adjacent plate elements 2. In this case, in the same opening areas 30a, 30b, 30c, 30d, the second heat transfer plates 20 are formed with closed protrusions 50, which are connected to the closed protrusions 50 of the first heat transfer plates 10 of the adjacent plate elements 2 on the opposite side.

[0052] Reference signs

[0053] 1 plate heat exchanger

[0054] 2 stacked plate elements

[0055] 3a, 3b, 3c, 3d opening

[0056] 10 first heat transfer plate

[0057] 20 second heat transfer plate

[0058] 30a, 30b, 30c, 30d opening area

[0059] 35a, 35b, 35c, 35d periphery

[0060] 40 heat exchange section

[0061] 45 surface pattern

[0062] 50 closed protrusion

[0063] 55 recess

[0064] 60 discharge opening

[0065] 65 open protrusion

[0066] 70 first leakage chamber

[0067] 75 opening

[0068] 80 second leakage chamber

[0069] 85 discharge channel

[0070] 200 first fixed portion at a first radial distance

[0071] 210 second fixed portion at a second radial distance

[0072] 220 third fixed portion at a third radial distance

[0073] 230 fourth fixed portion of the periphery at a fourth radial distance.

Claims

1. A plate heat exchanger (1), the plate heat exchanger (1) comprising a stacked layer of plate elements (2), each plate element (2) being a double-walled structure comprising a first heat transfer plate (10) and a second heat transfer plate (20), each heat transfer plate comprising a central heat exchange portion (40) having a surface pattern (45), the surface pattern (45) being adapted to allow the surface pattern (45) of the first heat transfer plate (10) of one plate element (2) to contact the surface pattern (45) of the second heat transfer plate (20) of an adjacent plate element (2), thereby forming a first flow path (A) for a first fluid on one side of the plate element (2) and a second flow path (B) for a second fluid on a second side of the plate element (2), wherein the plate element (2) has openings (3a, 3b, 3c, 3d) formed in opening regions (30a, 30b, 30c, 30d), characterized in that, The first heat transfer plate (10) has a closed protrusion (50) protruding in a first direction in the opening regions (30a, 30b, 30c, 30d), and the first heat transfer plate (10) has an open protrusion (65) in the same opening regions (30a, 30b, 30c, 30d), and the open protrusion (65) is formed in a second direction opposite to the first direction, such that the closed protrusion (50) and the open protrusion (65) together define a first leakage cavity (70). The open protrusion (65) is adapted to allow fluid to pass between the respective opening (3a, 3b, 3c, 3d) and the respective flow path when connected to the open protrusion (65) of the adjacent plate element (2), and the closed protrusion (50) is adapted to close the fluid and seal the respective opening (3a, 3b, 3c, 3d) relative to the respective flow path. Among them, multiple open protrusions (65) are positioned around the entire periphery of the corresponding openings (3a, 3b, 3c, 3d), and a single closed protrusion (50) surrounds the corresponding opening (3a, 3b, 3c, 3d).

2. The plate heat exchanger according to claim 1, wherein, The first fixing part (200) and the second fixing part (210) are positioned on opposite sides of the relevant openings (3a, 3b, 3c, 3d) to fix the first heat transfer plate (10) of the plate element (2) together with the second heat transfer plate (20).

3. The plate heat exchanger according to claim 1, wherein, The closed protrusion (50) is connected to the discharge channel (85), which is configured to fluidly connect the closed protrusion (50) to the outside of the plate heat exchanger (1).

4. The plate heat exchanger according to claim 3, wherein, The discharge channel (85) is formed as a protrusion in the same first direction as the closed protrusion (50).

5. The plate heat exchanger according to claim 1, wherein, A recess (55) is formed in the closed protrusion (50), and wherein the recess (55) protrudes in a second direction opposite to the closed protrusion (50) and into the first leakage cavity (70).

6. The plate heat exchanger according to claim 5, wherein, When the closed protrusion (50) is connected to the closed protrusion of the heat transfer plate of the adjacent plate element (2) to which it is connected, the recess (55) defines a second leakage cavity (80).

7. The plate heat exchanger according to claim 6, wherein, The second leakage cavity (80) is located between the corresponding third fixing part (220) and fourth fixing part (230) of the heat transfer plate that fixes the heat transfer plate to the adjacent plate element (2).

8. The plate heat exchanger according to any one of claims 6 to 7, wherein, An opening is formed in the plate wall shared by the closed protrusion (50) and the recess (55), thereby creating fluid communication between the first leakage cavity (70) and the second leakage cavity (80).

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