Gasket (for heat exchanger plate) and related device
A non-circular gasket design for plate heat exchangers addresses the challenge of pressure drop and heat transfer efficiency by adapting to port hole shape, reducing stress and filter interference, and allowing for efficient fluid flow with less powerful equipment.
Patent Information
- Application Number
- IR139250140003006812
- Authority / Receiving Office
- IR · IR
- Patent Type
- Patents
- Current Assignee / Owner
- Priority Date
- 2013-05-27
- Filing Date
- 2013-10-29
- Publication Date
- 2026-05-31
- Estimated Expiration
- 2033-10-29
Smart Images
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Abstract
Description
Gasket (for heat exchanger plate) and related device Technical background The present invention relates to a gasket according to the preamble of claim 1. The invention also relates to an assembly comprising a heat exchange plate and such a gasket. Technology background Plate heat exchangers typically consist of two end plates with a large number of heat transfer plates arranged in a row between them. In one well-known type of plate heat exchanger (PHE), known as a gasketed plate heat exchanger, gaskets are placed between the heat transfer plates, particularly along the edges and around the port holes of the heat transfer plates. The end plates, and thus the heat transfer plates, are pressed together, in which case the gaskets form a seal between the heat transfer plates. The gaskets define parallel flow channels between the heat transfer plates through which two fluids with different initial temperatures can alternately pass, transferring heat from one fluid to the other. For optimum performance of a gasketed plate heat exchanger, the design of the gaskets must be compatible with the design of other components of the plate heat exchanger, including the design of the heat transfer plates. **Fluids enter and exit the channels through inlet and outlet ports, respectively.** These ports extend throughout the plate heat exchanger and are formed by aligned port holes in the heat transfer plates. The inlet and outlet ports are connected to the inlets and outlets of the plate heat exchanger, respectively. To feed the two fluids through the plate heat exchanger, equipment such as a pump is required. The smaller the inlet and outlet ports, the greater the pressure drop of the fluids inside the plate heat exchanger, and more powerful and therefore more expensive equipment is required for its proper operation. Naturally, the diameter of the inlet and outlet ports can be made larger to reduce fluid pressure drop and allow for the use of less powerful equipment. However, increasing the diameter of the inlet and outlet ports means increasing the diameter of the port holes in the heat transfer plates. This in turn can result in a loss of valuable plate heat transfer area, which is usually associated with a decrease in the heat transfer efficiency of the plate heat exchanger. Summary The object of the present invention is to provide a gasket for a heat exchanger plate which has a relatively low pressure drop and can therefore be used in connection with relatively low-power peripheral equipment. As previously mentioned, for the optimum performance of a gasketed plate heat exchanger, the design of the gaskets must be adapted to the design of the rest of the plate heat exchanger components. For example, the gaskets should usually be designed to follow at least partially the edges of the heat exchanger plates and be located close to them in order to maximize the heat transfer surface of the plate heat exchanger. At the same time, the distance between the gasket and the edge should be large enough to provide sufficient support for the gasket at the edge. The basic concept of the invention is to provide a gasket adapted to a heat exchanger plate having at least one non-circular port hole instead of the conventional circular type. The port hole and thus the gasket can be adapted to the design of the same heat exchanger plate and also the port hole area can be expanded by sacrificing a portion of the plate surface that does not contribute significantly to the heat transfer performance of the plate. Another object of the present invention is to provide an assembly comprising a heat exchanger plate and such a gasket. The gasket and the assembly are defined in the appended claims and discussed below to achieve the above objects. A gasket for placement on a heat exchanger plate according to the present invention has an annular portion of the gasket designed to enclose a port hole of the heat exchanger plate.** The inner edge of the annular portion of the gasket defines a region that includes a reference point that coincides with the center of the largest imaginary circle that can be contained within this region. The characteristic of the washer is that the area defined by the inner edge of the annular portion of the washer has a shape defined by a number of corner points of an imaginary planar geometric shape. At least one of these corner points is displaced from the arc of said circle and the same number of perfectly uniform curved lines connect these corner points. A first corner point of the corner points is located at a first distance from the reference point. A second corner point, which is the closest point to the first corner point in the clockwise direction, is located at a second distance from the reference point. In addition, a third corner point, which is the closest point to the first corner point in the counterclockwise direction, is located at a third distance from the reference point. The geometric shape of the plane can be of various types, for example, triangle, quadrilateral, pentagon, etc. Therefore, the number of corner points or endpoints, and consequently curved lines, can vary from two points upwards. By perfectly curved lines are meant lines that have no straight sections. So the inner edge of the annular portion of the gasket will have a contour without any straight sections and will therefore match the port hole which has a contour without straight sections. This is advantageous because it results in relatively low bending stresses around the port hole. The fluid flowing through the port hole tends to make it circular. So if the port hole had straight sections, this would result in relatively high bending stresses in the heat exchanger plate. Each curved line connects two of the corner points. Since at least one of the corner points is displaced from the arc of the imaginary circle, the area defined by the annular portion of the washer will be non-circular. When referring to the orientation of the corner points, clockwise and counterclockwise refer to the direction in which the gasket is correctly positioned on the heat exchanger plate and viewed from a direction perpendicular to the heat exchanger plate. The property that the second and third corner points are the closest points to the first corner point in the clockwise and counterclockwise directions, respectively, indicates the relative positions of the first, second, and third points along the inner edge of the annular portion of the gasket. In the case of the first, second, and third distances between the reference point and the first, second, and third corner points, respectively, the shortest distance is meant. **The term "heat exchanger plate" used here includes both the end plates and the heat transfer plates of a plate heat exchanger, even though the main focus here is on the heat transfer plates.** The annular portion of the gasket is designed to lie along the edge of the port hole. The distance between the gasket portion and the edge of the port hole is essentially the same throughout the entire length of the gasket portion. Therefore, the area defined by the gasket portion is essentially the same as the area of the port hole (although obviously larger). Accordingly, the advantage of designing the gasket - or more specifically the gasket portion - with a particular shape is that it is matched to a port hole that has essentially the same shape. This shape, in turn, can be useful in a variety of ways. Keep in mind that, in the following discussion of various possible gasket features, reference will be made to the advantages of the port hole to which the gasket having these features is matched. According to an embodiment of the inventive gasket, the number of corner points and curved lines is equal to three. In this connection, the geometric shape of the corresponding plate can be a triangle. This embodiment is suitable for many conventional heat exchanger plates with a substantially rectangular shape and port holes located at the corners of the heat exchanger plate. The curved lines can be concave or convex from the reference point of the area defined by the annular portion of the gasket. Such a design allows for a relatively large area defined by the annular portion of the gasket, which is consequently adapted to a relatively large area of the port hole, which in turn is associated with a relatively low pressure drop. The gasket may be such that the first, second and third corner points lie on the first, second and third imaginary straight lines respectively extending from the zone reference point. A first angle between the first and second imaginary straight lines may be substantially equal to the third angle between the third and first imaginary straight lines. Furthermore, the gasket may be such that the second distance between the second corner point and the reference point is equal to the third distance between the third corner point and the reference point. These designs make it possible to match the gasket with a symmetrical port hole and thus a symmetrical annular gasket section, the axis of symmetry of which is parallel to the first imaginary straight line. A symmetrical port hole may facilitate the construction of the heat exchanger plate. According to the invention, the first distance between the first corner point and the reference point may be smaller than the second distance between the second corner point and the reference point and / or the third distance between the third corner point and the reference point. In this way, the gasket may be adapted to the shape of the port hole, which in turn is adapted to the design of the rest of the heat exchanger plate. In particular, depending on the design of the heat exchanger plate, there may be more space for the port hole to expand in the direction of the second and third corner points than in the direction of the first corner point. The annular portion of the gasket may be such that a first curved line of the curved lines connecting the first and second corner points and a third curved line of the curved lines connecting the third and first corner points are similar but mirror images of each other. Such uniform curved lines make it possible to have a symmetrical gasket that is matched with a symmetrical port hole whose axis of symmetry is parallel to the first imaginary straight line. As previously mentioned, a symmetrical port hole may facilitate the fabrication of the heat exchanger plate. The assembly according to the present invention comprises a heat exchanger plate and a gasket as described above. Other objects, features, aspects and advantages of the invention will become apparent from the detailed description that follows as well as from the drawings. **Brief description of maps** The invention will now be described in more detail with reference to the accompanying schematic drawings, in which: Figure 1: Front view of a plate heat exchanger Figure 2: Side view of the plate heat exchanger of Figure 1 Figure 3: Top view of an assembly according to the invention, namely a heat transfer plate equipped with a gasket Figure 4: Schematic view of part of the gasket of Figure 3 Figure 5: Shows the gasket of Figure 3 in cross section. **Detailed description** Referring to Figures 1 and 2, a gasketed plate heat exchanger (2) is shown. The exchanger comprises heat exchanger plates in the form of a first end plate (4), a second end plate (6) and a number of heat transfer plates which are respectively located between the first and second end plates (4 and 6). The heat transfer plates are of two different types. However, since this is not relevant to the present invention, the difference between the two types of heat transfer plates will not be discussed further here. One of the heat transfer plates, designated by the numeral (8), is shown in more detail in Figure 3. The different types of heat transfer plates are arranged alternately in a plate pack (9) in which the front surface (shown in Figure 3) of one heat transfer plate is positioned opposite the back surface of the adjacent heat transfer plate. Each second heat transfer plate is rotated 180° relative to a reference direction (shown in Figure 3) about a direction perpendicular to the plane of Figure 3. The heat transfer plates are separated from each other by gaskets, one of which is indicated by the number (11) and is shown in more detail in Figures 3 and 4. Also shown in Figure 5 is a cross-section of the gasket (11). The heat transfer plates, together with the gaskets, form parallel channels designed to receive two fluids and transfer heat from one to the other. For this purpose, a first fluid flows in each second channel and a second fluid flows in the remaining channels. The first fluid enters and leaves the plate heat exchanger (2) through inlet (10) and outlet (12), respectively. Similarly, the second fluid enters and leaves the plate heat exchanger (2) through inlet (14) and outlet (16), respectively. To seal the channels, the heat transfer plates must be pressed together so that the gaskets between them form a seal. For this purpose, the plate heat exchanger (2) includes a number of tightening means (18) designed to press the first and second end plates (4 and 6) towards each other. The heat transfer plate 8 is a substantially rectangular sheet of stainless steel. This plate has a central expansion plate cc (see FIG. 2) which is parallel to the plate of FIG. 3. The heat transfer plate 8 includes an inlet port hole (20) for the first fluid and an outlet port hole (22) for the second fluid which are respectively connected to the inlet (10) and outlet (16) of the plate heat exchanger 2. In addition, the heat transfer plate 8 includes an inlet port hole (24) for the second fluid and an outlet port hole (26) for the first fluid which are respectively connected to the inlet (14) and outlet (12) of the plate heat exchanger 2. The inlet and outlet port holes will not be described in detail here. Instead, reference is made to the co-pending patent application EP12190496.5, which is hereby incorporated herein by reference. The heat transfer plate 8 also includes various regions, namely two distribution regions (28 and 30), a heat transfer region (32) extending between the distribution regions, and adiabatic regions (34, 36, 38 and 40) extending between the inlet and outlet port holes and the distribution regions. Each of these regions has a corrugated pattern (not shown) in the form of ridges and depressions relative to the central expansion plate cc, the design of which corrugation depends on the primary function of the region. The main function of the distribution zones 28 and 30 is to spread a fluid across the width of the heat transfer plate 8. The main function of the heat transfer zone 32 is to transfer heat from the fluid on one side of the heat transfer plate 8 to the fluid on the other side of the plate. The main function of the adiabatic zones 34, 36, 38 and 40 is to guide the fluid between the inlet and outlet port holes (20, 22, 24 and 26) and the distribution zones (28 and 30), i.e. they are simply zones for fluid transfer. The various zones and corrugation patterns will not be described in detail here. Instead, reference is made to the co-applicant patent EP12190493.2. The heat transfer plate 8 is provided with a gasket groove designed to receive a gasket 11 made of rubber. When the gasket 11 is properly seated in the groove, it extends along the long sides 42 and 44 and the short sides 46 and 48 of the heat transfer plate 8 and also diagonally across the plate, a design common to most heat transfer plates and gaskets. Specifically, the gasket 11 comprises two annular gasket sections 50 and 52 which surround the outlet port hole 22 and the inlet port hole 24, respectively. The annular gasket sections 50 and 52 are similar, so only one of them, section 52, will be described below. The annular portion of the washer 52 is positioned along the edge of the hole 54 of the port 24. The distance between the inner edge 56 of the annular portion of the washer 52 and the edge of the hole 54 of the port 24 is the same throughout the entire length of the annular portion. In other words, the design of the annular portion of the washer 52 is adapted to the shape of the hole of the port 24. Thus, the inner edge 56 of the annular portion of the washer 52 defines an area 58 (FIG. 4) that is identical to the hole of the port 24, but larger than it. The annular portion of the washer 52 is shown schematically and in dashed lines for clarity, separately in FIG. 4. The region 58 defined by it has an external contour defined by the first, second and third corner points (66, 68 and 70) of an imaginary triangle 72 (dashed lines). In addition, these corner points are connected to each other by the first, second and third curved lines (74, 76 and 78) which are seen concavely from the inlet port hole. A reference point 80 of the region 58 coincides with the center point C of the largest imaginary circle 82 (dotted lines) which can be placed within the region. The first corner point 66 is located on a first imaginary straight line 86 extending from the reference point 80 and at a first distance d1 from the reference point. The second corner point 68 is the point closest to the first corner point in a clockwise direction. Furthermore, this point lies on a second imaginary straight line 88 extending from the reference point 80 and at a second distance d2 from the reference point. The third corner point 70 is the closest point to the first corner point in a counterclockwise direction.Also, this point lies on a third imaginary straight line 90 extending from the reference point 80 and is located at a third distance d3 from the reference point. For the first, second, and third intervals mentioned above, the following relationships hold: d2 = d3 and d2 > d1 Furthermore, the first angle α1 between the first and second hypothetical straight lines is smaller than the second angle α2 between the second and third hypothetical straight lines and is essentially equal to the third angle α3 between the third and first hypothetical straight lines. In other words, the following relations hold for the first, second, and third angles: α1 = α3 and α1 < α2 In this particular example, α1 = α3 = 115 degrees. Furthermore, the first curved line 74 connecting the first and second corner points (66 and 68) is essentially the same as the third curved line 78 connecting the third and first corner points (70 and 66). In sum, this means that the region 58 is symmetrical and has an axis of symmetry s passing through the first corner point 66 and the reference point 80. As is evident from the figures and the above description, since the inlet port hole 24 is not of a conventional circular shape, neither is the annular portion of the gasket 52. Instead, they have a shape defined by a number of corner points (here three points) at least one of which (here all) is offset from the arc 92 of the circle 82, and an equal number of curved lines (here three lines) connecting these corner points. If the inlet port hole 24 were circular, the annular portion of the gasket 52 would preferably have an inner edge 56 that coincides with the arc 92 of the circle 82. From a pressure drop perspective, a very large inlet port hole would be preferable, given the previous discussions in this regard. However, the design of the rest of the heat transfer plate 8 limits the possible size of the inlet port hole. For example, a larger circular inlet port hole would mean that the contour of the inlet port hole is closer to the short side 48 and / or the long side 44, which could lead to strength problems in the heat transfer plate 8. In addition, a larger circular inlet port hole could also mean that the area between the inlet port hole 24 and the distribution area 30 (Figure 3) may be too narrow for the gasket to be accommodated. Such a narrow intermediate area could also cause problems in the process of pressing the heat transfer plate with the previously mentioned corrugated patterns. Naturally, the distribution area 30 of the heat transfer plate 8 could be moved lower down the heat transfer plate to make room for a larger circular inlet port hole 24. However, this would typically be accompanied by a reduction in the heat transfer area 32 and thus a reduction in the heat transfer capability of the heat transfer plate. As described above and illustrated in the figures, the area of the inlet port hole can be increased without having to change the design of the rest of the heat transfer plate. By allowing the inlet port hole to occupy a larger portion of the adiabatic area 38 of the heat transfer plate 8 than a circular inlet port hole, a larger inlet port hole with lower pressure drop can be achieved. Since only the adiabatic area is affected by this expansion, the heat distribution and transfer capability of the heat transfer plate 8 remains essentially unchanged. Furthermore, since the contour of the inlet port hole 24 lacks straight sections, the bending stresses around the inlet port hole will be relatively low. Another advantage of the non-circular inlet port hole described above relates to the installation of gaskets and filters. The gasket 11 includes clamping means 60 and 62 designed to engage the edge of the heat transfer plate 8 and secure the gaskets to the plate. In some plate heat exchanger applications, for example in applications involving the processing of contaminated fluids, internal filters are used to prevent contamination from entering the channels between the heat transfer plates. These internal filters are typically circular in shape and pass through the inlet and / or outlet ports of the plate heat exchanger, i.e., through the inlet and outlet port holes of the heat transfer plates. If, as is conventional, the inlet and outlet port holes of the heat transfer plates are circular, the gasket clamping means may interfere with the internal filters.However, if the annular portion of the gasket and the inlet and outlet port holes are instead shaped similar to those described above, the gaskets can be adapted so that the gasket clamping devices engage the heat transfer plate at the corner points of the inlet and outlet port holes. This way, there is no risk of interference between the gaskets and the circular cylindrical filters. The clamping devices 60 and 62 are of different types and are not described in detail herein. Instead, for a detailed description of the clamping device 60, reference is made to the co-pending patent application EP 13153167.5, which is hereby incorporated by reference. The described embodiment of the present invention should be considered as an example only. It will be understood by a person skilled in the art that the embodiment in question can be modified in various ways without departing from the scope of the invention. The end plates 4 and 6 of the plate heat exchanger 2 described above are conventionally designed with circular inlets and outlets. However, the end plates can also be equipped with non-circular inlets and outlets similar to the inlet and outlet port holes described above. Also, as previously noted, the shape of the region defined by the annular portion of the washer is specified by a hypothetical planar geometric shape in the form of a triangle, three corner points, and three curved lines. It is obvious that in alternative embodiments, other hypothetical planar geometric shapes, as well as a different number of corner points and curved lines, can be used to define the region. The inlet port hole described above, and consequently the annular portion of the gasket, has an axis of symmetry (s). Of course, the inlet port hole and the annular portion of the gasket can be completely asymmetrical or even more symmetrical by having more than one axis of symmetry. For example, the curved lines can all be uniform or non-uniform and / or the distance to the reference point for all corner points can be the same or different. The curved lines also do not have to be concave. One or more curved lines may have other shapes. The plate heat exchanger described above is of the parallel counterflow type, i.e. the inlet and outlet for each fluid are located in one half of the plate heat exchanger and the fluids flow in opposite directions through the channels between the heat transfer plates. Naturally, the plate heat exchanger can instead be of the diagonal flow and / or co-flow type. The above plate heat exchanger consists of two different types of heat transfer plates and one type of gasket between them. It is obvious that a plate heat exchanger can consist of only one type of plate or more than two different types of plates. In addition, the heat transfer plates can be made of materials other than stainless steel. A plate heat exchanger can also have more than one type of gasket between the heat transfer plates, and the gaskets can be made of materials other than rubber. The gasket can also consist of only the annular portion of the gasket, i.e., be designed as a ring gasket. Other methods than clamping devices can also be used to attach the gasket to the heat transfer plate, such as glue or tape, or some other type of mechanical mounting device. Finally, the present invention can be applied in connection with other types of plate heat exchangers other than gasketed types, such as plate heat exchangers consisting of semi / fully permanently bonded heat transfer plates. It is emphasized that the features "first", "second", "third" and the like are used here to distinguish between members of a category and do not indicate any particular order between them. It is emphasized that the description of details not relevant to the present invention has been omitted and the figures are schematic only and not drawn to scale. It should also be noted that some figures are more simplified than others. Therefore, some components may be depicted in one figure but omitted in another.
Claims
Claims of the invention:
1. A gasket (11) for positioning and sealing between adjacent first and second heat transfer plates (8) in a plate heat exchanger, comprising an annular gasket portion (52) designed to enclose a port hole (24) of the first heat transfer plate. The inner edge (56) of the annular gasket portion defines a region (58) including a reference point (80) coincident with the center point (C) of the largest imaginary circle (82) that can be placed in the region, **It is characteristic that** this area has a shape defined by the following: - a number of corner points of a hypothetical planar geometric figure (72), at least one of which is displaced from the arc (92) of the circle, and - The same number of curved lines (74, 76, 78) that lack straight segments and connect the corner points, Such that a first corner point (66) of the corner points is located at a first distance (d1) from the reference point, a second corner point (68) which is the closest point to the first corner point in the **clockwise direction** is located at a second distance (d2) from the reference point, and a third corner point (70) which is the closest point to the first corner point in the **counterclockwise direction** is located at a third distance (d3) from the reference point. This region (58) has only one axis of symmetry (s) which passes through the first corner point (66) and the reference point (80).
2. The washer (11) according to claim 1, wherein the number of corner points (66, 68, 70) and curved lines (74, 76, 78) is equal to three.
3. A gasket (11) according to any preceding claim, wherein the curved lines (74, 76, 78) are **concave** from the point of reference (80) of the region.
4. A washer (11) according to any preceding claim, wherein the first distance (d1) between the first corner point (66) and the reference point (80) is smaller than the second distance (d2) between the second corner point (68) and the reference point.
5. A washer (11) according to any preceding claim, wherein the first distance (d1) between the first corner point (66) and the reference point (80) is smaller than the third distance (d3) between the third corner point (70) and the reference point.
6. An assembly comprising first and second heat transfer plates (8) and a gasket (11) according to any one of the preceding claims.