Heat transfer plate and cassette for plate heat exchanger

Abstract

A heat transfer plate includes a first bar engagement comprising a first recess and a first edge portion surrounding the first recess, and a second bar engagement portion comprising a second recess and a second edge portion surrounding the second recess. A part of the first edge portion extends from a first plane to a parallel third plane, and a part of the second edge portion extends from the first plane to a fourth plane. The second and third planes are on the same side of the first plane, the third and fourth planes are a distance from the first plane, and the at least a part of the first edge portion projects from a front of the plate. An edge of the first edge portion defines a first area and an edge of the second edge portion defines a second area, the first area fitting inside the second area.

Claims

1. A heat transfer plate for a plate heat exchanger, having a thickness t and comprising first and second opposing sides, a first bar engagement portion along the first side, a second bar engagement portion along the second side, and an outer edge part comprising corrugations extending between and in first and second planes, which first and second planes are parallel to each other, a distance between the first and second plane=x, the first bar engagement portion comprising a first recess for receiving a first bar of the plate heat exchanger and a first edge portion surrounding the first recess, and the second bar engagement portion comprising a second recess for receiving a second bar of the plate heat exchanger and a second edge portion surrounding the second recess, at least a part of the first edge portion extending from the first plane to a third plane which is parallel to the first plane, and at least a part of the second edge portion extending from the first plane to a fourth plane which is parallel to the first plane, wherein the second and third planes are arranged on the same side of the first plane, the third plane is arranged on a distance d1>0 from the first plane such that said at least a part of the first edge portion projects from a front of the heat transfer plate, the fourth plane is arranged on a distance d2≥0 from the first plane, and an edge of the first edge portion defines a first area and an edge of the second edge portion a second area, wherein the first area fits inside the second area.

2. A heat transfer plate according to claim 1, wherein the first and second recesses extend from the first and second sides, respectively.

3. A heat transfer plate according claim 1, wherein d2=d1.

4. A heat transfer plate according to claim 1, wherein d2<d1.

5. A heat transfer plate according to claim 1, wherein the first and third planes are arranged on opposite sides of the second plane.

6. A heat transfer plate according to claim 1, wherein d1>(x+0.5t).

7. A heat transfer plate according to claim 1, wherein the first and fourth planes are arranged on opposite sides of the second plane.

8. A heat transfer plate according to claim 1, wherein d2>(x+0.5t).

9. A heat transfer plate according to claim 1, wherein the distance d1 between the first and third planes is ≤(2x+1.5t).

10. A heat transfer plate according to claim 1, wherein the distance d2 between the first and fourth planes is ≤(2x+0.5t).

11. A heat transfer plate according to claim 1, further comprising a gasket groove extending on a back of the heat transfer plate, a bottom of the gasket groove extending in the second plane.

12. A heat transfer plate according to claim 1, wherein the first and second areas are essentially uniform.

13. A heat transfer plate according to claim 1, wherein a respective center of the first and second recesses is arranged on an imaginary straight recess center line extending parallel to a longitudinal center axis of the heat transfer plate.

14. A cassette for a plate heat exchanger, comprising bonded first and second heat transfer plates according to claim 1, wherein the second heat transfer plate is rotated 180 degrees about a transverse center axis in relation to the first heat transfer plate, a front of the first heat transfer plate abuts a front of the second heat transfer plate, the first area of the first heat transfer plate is arranged within the second area of the second heat transfer plate, and the first area of the second heat transfer plate is arranged within the second area of the first heat transfer plate.

15. A cassette for a plate heat exchanger, comprising bonded first and second heat transfer plates according to claim 1, wherein the second heat transfer plate is rotated 180 degrees about a transverse center axis in relation to the first heat transfer plate, a back of the first heat transfer plate abuts a back of the second heat transfer plate, the first area of the first heat transfer plate is arranged within the second area of the second heat transfer plate, and the first area of the second heat transfer plate is arranged within the second area of the first heat transfer plate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will now be described in more detail with reference to the appended schematic drawings, in which

(2) FIG. 1 is a schematic front view of a semi-welded plate heat exchanger,

(3) FIG. 2 is a schematic side view of the plate heat exchanger in FIG. 1,

(4) FIG. 3 is a schematic plan view of a heat transfer plate illustrating a front thereof,

(5) FIG. 4 is a schematic plan view of a heat transfer plate illustrating a back thereof, and a schematic plan view of a cassette,

(6) FIG. 5 illustrates abutting outer edge parts of adjacent heat transfer plates in a plate pack, as seen from the outside of the plate pack,

(7) FIG. 6 is a schematic cross section of the cassette taken along line A-A in

(8) FIG. 4,

(9) FIG. 7 is a schematic cross section of the cassette taken along line B-B in FIG. 4,

(10) FIG. 8 is an enlargement of a first bar engagement portion of the heat transfer plate in FIG. 3,

(11) FIG. 9 is an enlargement of a second bar engagement portion of the heat transfer plate in FIG. 3,

(12) FIG. 10 is a schematic cross section of another cassette, corresponding to the cross section in FIG. 6,

(13) FIG. 11 is a schematic cross section of said another cassette, corresponding to the cross section in FIG. 7,

(14) FIG. 12 is a schematic cross section of yet another cassette, corresponding to the cross section in FIG. 6,

(15) FIG. 13 is a schematic cross section of said yet another cassette, corresponding to the cross section in FIG. 7,

(16) FIG. 14 is a schematic cross section of yet a further cassette, corresponding to the cross section in FIG. 6, and

(17) FIG. 15 is a schematic cross section of said yet a further cassette, corresponding to the cross section in FIG. 7.

DETAILED DESCRIPTION

(18) FIGS. 1 and 2 show a semi-welded gasketed plate heat exchanger 2 as described by way of introduction. It comprises a frame plate 4, a pressure plate 6, a pack of heat transfer plates 8, fluid inlets and outlets 10, tightening means 12, an upper bar 14 and a lower bar 16.

(19) The heat transfer plates 8, hereinafter also referred to as just “plates”, are all similar. Two of them, denoted 8a and 8b, are illustrated in further detail in FIGS. 3 and 4, respectively. The plates 8a and 8b are essentially rectangular sheets of stainless steel. They comprise two opposing long sides 18, 20 and two opposing short sides 22, 24. Further, the plates each has a longitudinal center axis 26 extending parallel to, and half way between, the long sides 18, 20, and a transverse center axis 28 extending parallel to, and half way between, the short sides 22, 24 and thus perpendicular to the longitudinal center axis 26. Each of the plates 8a, 8b has a front 30 (illustrated in FIG. 3), a back 32 (illustrated in FIG. 4), a gasket groove 34 extending on the back 32 and four port holes 36, 38, 40 and 42.

(20) The heat transfer plates 8a, 8b are pressed, in a conventional manner, in a pressing tool, to be given a desired structure, such as different corrugation patterns within different portions of the heat transfer plate. The corrugation patterns are optimized for the specific functions of the respective plate portions. Accordingly, the plates 8a, 8b comprise two distribution areas 44 which each is provided with a distribution pattern adapted for optimized fluid distribution across the heat transfer plate. Further, the plates 8a, 8b comprise a heat transfer area 46 arranged between the distribution areas 44 and provided with a heat transfer pattern adapted for optimized heat transfer between two fluids flowing on opposite sides of the heat transfer plate. Moreover, the plates 8a, 8b comprise an outer edge part 48 extending along an outer edge 50 of the plates. The outer edge part 48 comprises corrugations 52 arranged to abut corrugations of adjacent plates in the plate pack of the plate heat exchanger 2. Depending on the design of the distribution and heat transfer patterns, the plates 8a, 8b may or may not be arranged to abut the adjacent heat transfer plates also within the distribution and heat transfer areas 44 and 46, respectively. However, this is not further discussed herein.

(21) In the plate pack of the plate heat exchanger 2, the plates are arranged with the front 30 and the back 32 of one plate 8 facing the front and the back, respectively, of the neighboring heat transfer plates. Further, every second plate 8 is rotated 180 degrees (as illustrated in FIG. 4), in relation to a reference orientation (illustrated in FIG. 3), around a normal direction of the figure plane of FIG. 3. FIG. 5 illustrates the contact between the corrugations 52 of the outer edge parts 48 of the plates 8a and 8b and another plate 8c in the plate pack of the plate heat exchanger 2. As is illustrated for the plate 8a, the corrugations 52 extend between and in a first plane 54 and a second plane 56, which are parallel to the figure plane of FIG. 3. The first and second planes 54, 56 are separated by a distance x. A bottom of the gasket groove 34 (illustrated in FIG. 4) on the back 32 of the plates extends in the second plane 56. As is illustrated in FIG. 5, the plates have a thickness t.

(22) The plates 8 of the plate pack are welded together in pairs, front 18 to front 18, to form cassettes 57. FIG. 4 shows one of the cassettes 57 comprising the plate 8a illustrated in FIG. 3 (not visible in FIG. 4) and the plate 8b visible in FIG. 4. The plates 8a and 8b are welded together along a weld line 58, illustrated with dashed lines in FIG. 3. The weld line 58 is discontinuous and partly aligned with the gasket groove 34 (not visible) on the back 32 of the plate 8a. On the left side, as seen in FIGS. 3 and 4, of the heat transfer plates 8a, 8b, the weld line 58 extends outside the gasket groove 34. In the plate pack of the plate heat exchanger 2, the welded cassettes 57 are separated by gaskets 60, which gaskets 60 are all similar, one of these gaskets 60 being illustrated in FIG. 4. Each of the gaskets 60 is arranged in the opposing gasket grooves 34 of two adjacent heat transfer plates 8 comprised in two adjacent cassettes 57. Here, each of the gaskets 60 is discontinuous so as to comprise a field portion 60a and two separate porthole portions 60b. However, in alternative embodiments the gasket could be continuous such that the field and porthole portions thereof are integrally formed.

(23) Details of the heat transfer plates 8 will now be described with reference particularly to plate 8a and FIGS. 3 and 6-9. The plate 8a comprises a first bar engagement portion 62 along the short side 22 and a second bar engagement portion 64 along the short side 24. In turn, the first bar engagement portion 62 comprises a first recess 66 for receiving a first bar or the upper bar 14 (FIG. 2) of the plate heat exchanger 2 and a first edge portion 68 with an edge 70 surrounding the first recess 66 (FIGS. 3, 6, 8). Similarly, the second bar engagement portion 64 comprises a second recess 72 for receiving a second bar or the lower bar 16 (FIG. 2) of the plate heat exchanger 2 and a second edge portion 74 with an edge 76 surrounding the second recess 72 (FIGS. 3, 7, 9). The first and second recesses 66 and 72 extend from the respective short sides 22 and 24, respectively. As illustrated in FIGS. 8 and 9, a respective center C1 and C2 of the first and second recesses 66 and 72 is arranged on an imaginary straight recess center line 77 extending parallel to the longitudinal center axis 26 of the heat transfer plate 8a. The imaginary straight recess center line 77 is displaced to the right of the longitudinal center axis 26 to make room for the weld line 58 extending outside the gasket groove 34 on the left side of the heat transfer plate 8a.

(24) As is clear from FIG. 6, the first edge portion 68 extends from the first plane 54 to a third plane 78 which is parallel to the first plane 54. As is clear from FIG. 7, the second edge portion 74 extends from the first plane 54 to a fourth plane 80 which is parallel to the first plane 54. The second and third planes 56 and 78 are arranged on the same side of the first plane 54, and the third plane 78 is arranged on a distance d1>0, more particularly 2x+1.5t, from the first plane 54. This means that the first edge portion 68 forms a first collar projecting from the front 30 of the heat transfer plate 8a. The second and fourth planes 56 and 80 are arranged on the same side of the first plane 54, and the fourth plane 80 is arranged on a distance d2>0, more particularly x+0.5t, from the first plane 54. This means that the second edge portion 74 forms a second collar projecting from the front 30 of the heat transfer plate 8a.

(25) With reference to FIG. 8, the edge 70 of the first edge portion 68 together with a first imaginary straight line 82 closing the first recess 66 define a first area 84. Similarly, with reference to FIG. 9, the edge 76 of the second edge portion 74 together with a second imaginary straight line 86 closing the second recess 72 define a second area 88. The first and second areas 84 and 88 are uniform, i.e. have the same shape, but the first area 84 is smaller than, and thus fits inside, the second area 88.

(26) The above description is valid also for the heat transfer plate 8b, except that the first recess 66 of the first bar engagement portion 62 of the plate 8b is arranged for receiving the lower bar 16 (FIG. 2) of the plate heat exchanger 2, while the second recess 72 of the second bar engagement portion 64 of the plate 8b is arranged for receiving the upper bar 14 (FIG. 2) of the plate heat exchanger 2.

(27) With reference to FIGS. 6 and 7, in the cassette 57 comprising the heat transfer plates 8a and 8b, the plates 8a and 8b have the orientations illustrated in FIGS. 3 and 4, respectively, and, as already said, they abut each other front 30 to front 30. Further, the second edge portion 74 of the plate 8a surrounds the first edge portion 68 of the plate 8b such that the first area 84 defined by the edge 70 of the first edge portion 68 of the plate 8b is within the second area 88 defined by the edge 76 of the second edge portion 74 of the plate 8a. Similarly, the second edge portion 74 of the plate 8b surrounds the first edge portion 68 of the plate 8a such that the first area 84 defined by the edge 70 of the first edge portion 68 of the plate 8a is within the second area 88 defined by the edge 76 of the second edge portion 74 of the plate 8b. As is clear from FIGS. 6 and 7, since the plates 8a and 8b have differently designed first and second bar engagement portions 62, 64, the first and second edge portions 68, 74 of the plates 8a, 8b will not interfere with each other in the cassette 57 even if they extend beyond the respective second plane 56 of the plates 8a, 8b so as to form relatively strong collars. Further, since the first and second edge portions 68, 74 of the plates 8a, 8b do not extend beyond the cassette 57, they will not interfere with other cassettes of the plate pack of the plate heat exchanger 2 irrespective of their inclination in relation to the first plane 54.

(28) When the cassette 57 is arranged in the plate heat exchanger 2, the upper bar 14 extends through the first recess 66 of the plate 8a and the second recess 72 of the plate 8b, with the first edge portion 68 of the plate 8a, which forms a deeper and thus stronger collar than the second edge portion 74 of the plate 8b, closest to the upper bar 14. Similarly, the lower bar 16 extends through the first recess 66 of the plate 8b and the second recess 72 of the plate 8a, with the first edge portion 68 of the plate 8b, which forms a deeper and thus stronger collar than the second edge portion 74 of the plate 8a, closest to the lower bar 16.

(29) FIGS. 10 and 11 illustrate a cassette 90 comprising heat transfer plates 92 which are designed like the heat transfer plates 8a, 8b except for when it comes to the second bar engagement portion. Hereinafter, only the differences between the second bar engagement portions of the plates 92 and 8a, 8b will be described. The plates 92 comprise a respective second bar engagement portion 94 in turn comprising a second recess 96 for receiving the upper or lower bar 14, 16 (FIG. 2) of the plate heat exchanger 2 and a second edge portion 98 with an edge 100 surrounding the second recess 96. The second edge portion 98 extends from a first plane 54 to a fourth plane 102. The fourth plane 102 is arranged on a distance d2=0 from the first plane 54, i.e. the fourth plane 102 coincides with the first plane 54. This means that the second edge portion 98 is plane and extends parallel to the first plane 54 and therefore forms no collar projecting from a front 30 of the heat transfer plate 90. The edge 100 of the second edge portion 98 together with a second imaginary straight line (not illustrated) closing the second recess 96 define a second area which is uniform with, but larger than, a first area defined by a first bar engagement portion of the plates 92.

(30) In the cassette 90 comprising the heat transfer plates 92, one of the plates 92 is turned up-side-down in relation to the other plate, and the plates are welded to each other front 30 to front 30. Further, the second edge portion 98 of each of the plates 92 surrounds a first edge portion 68 of the other plate 92. Since the plates 92 have differently designed first and second bar engagement portions, the first and second edge portions 68, 98 of the plates 8a, 8b will not interfere with each other in the cassette 90 even if the first edge portion 68 extend beyond respective second planes 56 of the plates so as to form a relatively strong collar.

(31) The above described embodiments of the present invention should only be seen as examples. A person skilled in the art realizes that the embodiments discussed can be varied in a number of ways without deviating from the inventive conception.

(32) As an example, the third plane can be arranged on another distance, both larger and smaller, from the first plane than the distance in the embodiments described. Similarly, the fourth plane can be arranged on another distance from the first plane than the distances in the embodiments described. For example, as is illustrated in FIGS. 12 and 13, the third and fourth planes can be arranged on the same distance from the first plane such that the collars formed by the first and second edge portions of the plate have the same collar depth, i.e. such that d1=d2.

(33) In the above described embodiments, the plates and the gaskets between the cassettes are all similar, but this is not mandatory. As an example, in a plate pack, plates of different types may be combined.

(34) Any collar formed by the first and second edge portions of the plate need not have a constant, but may have a varying, collar depth ≥0 along its extension.

(35) In the above described embodiments, the heat transfer plates of a cassette are arranged such that the collars of the plates point towards each other. In alternative embodiments, as is illustrated in FIGS. 14 and 15, the plates of a cassette could instead be arranged such that the collars point away from each other. Then, if the plates have the features as specified in the independent claim, the collars of the cassette will not interfere with the collars of other cassettes in a plate pack.

(36) The plates could be alternatively “rotated” instead of alternatively “flipped” in relation to each other as in the above described embodiments.

(37) The inventive heat transfer plate could be used in connection with other types of plate heat exchangers than semi-welded ones, for example gasketed plate heat exchangers.

(38) In the above first described embodiment, the first and second edge portions extend on the same side of the heat transfer plate and the edges of the first and second edge portions point away from the plate. In an alternative embodiment, the first and second edge portions could still extend on the same side of the heat transfer plate but one of the edges of the first and second edge portions could point away from, and the other one could point towards, the plate (for example by being bent 180 degrees).

(39) It should be stressed that the attributes first, second, third, etc. is used herein just to distinguish between species of the same kind and not to express any kind of mutual order between the species.

(40) 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.

LIST OF REFERENCE NUMERALS

(41) 2 semi-welded gasketed plate heat exchanger 4 frame plate 6 pressure plate 8 heat transfer plate 8a (first) heat transfer plate 8b (second) heat transfer plate 10 fluid inlets and fluid outlet 12 tightening means 14 upper bar (first bar) 16 lower bar (second bar) 18, 20 long sides 22, 24 short sides (first and second sides) 26 longitudinal centre axis 28 transverse centre axis 30 plate front 32 plate back 34 gasket groove 36, 38, 40, 42 port holes 44 distribution area 46 heat transfer area 48 outer edge part 50 outer edge 52 corrugations 54 first plane 56 second plane 57 cassette 58 weld line 60 gasket 60a gasket field portion 60b gasket porthole portion 62 first bar engagement portion 64 second bar engagement portion 66 first recess 68 first edge portion 70 edge of the first edge portion 72 second recess 74 second edge portion 76 edge of the second edge portion 77 imaginary straight recess center line 78 third plane 80 fourth plane 82 first imaginary straight line 84 first area 86 second imaginary straight line 88 second area 90 cassette 92 heat transfer plates 94 second bar engagement portion 96 second recess 98 second edge portion 100 edge of the second edge portion 102 fourth plane C1 center of first recess C2 center of second recess d1 distance between first and third planes d2 distance between first and fourth planes t plate thickness x distance between first and second planes