WO2008034812A1

WO2008034812A1 - A plate heat exchanger

Info

Publication number: WO2008034812A1
Application number: PCT/EP2007/059809
Authority: WO
Inventors: Peter BJÖRNSSON; Thord Gudmundsson
Original assignee: Alfa Laval Corporate Ab
Priority date: 2006-09-22
Filing date: 2007-09-18
Publication date: 2008-03-27
Also published as: SE0601973L; ES2374322T3; PL2064507T3; EP2064507A1; EP2064507B1; SE531819C2; ATE534008T1

Abstract

The invention refers to a plate heat exchanger comprising a plate package (1) with a frame plate (2) and a plurality of heat exchanger plates. The heat exchanger plates are provided beside each other and form a number of plate interspaces which comprise first plate interspaces for a first medium with a relatively low first working pressure, and second plate interspaces for a second medium with a relatively high second working pressure. Four ports (11-14) extend through the frame plate and the heat exchanger plates. The plate package comprises a first attachment member (30), which is located at a first short side (1 a) and a second attachment member (40), which is located at the second short side (1 b). The attachment members are positioned in relation to the centre axis (x) of the plate package and the ports in such a manner that forces caused by the difference between the first working pressure and the second working pressure are balanced.

Description

A plate heat exchanger

THE FIELD OF THE INVENTION

The present invention refers to a plate heat exchanger according to the preamble of claim 1.

THE BACKGROUND OF THE INVENTION AND PRIOR ART.

In such plate heat exchangers having first plate interspaces for a first medium with a relatively low first working pressure and with second plate interspaces for a second medium with a relatively high second working pressure, stresses and forces may arise, which are asymmetric with regard to the centre axis extending centrally along the frame plate of the plate package in the middle of the portholes and substantially in parallel with the long sides of the plate package. Such asymmetric forces may lead to an increased load on the attachment of the plate package, in particular on the side where the ports relate to the second media with the highest working pressure.

US 2005/0121 182 discloses an oil cooler having a plate package comprising a frame plate, a pressure plate and a plurality of heat exchanger plates between the frame plate and the pressure plate. The heat exchanger plates are provided beside each other and form first plate interspaces for the oil and second plate in- terspaces for a cooling medium. The frame plate and each of the heat exchanger plates have four portholes, which form four ports extending through the frame plate and the heat exchanger plates. The frame plate comprises a plurality of attachment members located around and outside the periphery of the plate package. SUMMARY OF THE INVENTION

The object of the present invention is to provide an improved attachment for a plate package of a plate heat exchanger in- tended for receiving two heat exchanger media with different working pressures.

This object is achieved by the plate heat exchanger initially defined, which is characterised in that the attachment members are asymmetrically positioned in relation to the centre axis and the ports in such a way that forces caused by the difference between the first working pressure and the second working pressure are balanced, wherein all first one or several attachment members and all second one or several second attachment members have a common geometric centre of gravity located beside the centre axis. By means of such an asymmetric positioning of the attachment members in relation to the centre axis and the ports, non-equally distributed forces caused by different working pressures of the heat exchanger media may be bal- anced. The exact positioning of the attachment members may be calculated from the number of attachment members, the actual working pressures and the positioning of the ports in relation to each other and the centre axis.

All attachments thus have a common geometric centre of gravity represented by a force centre for the forces, which may be absorbed by the attachments. This force centre may thus be located beside the centre axis and advantageously in the proximity of, in the same point as or substantially in the same point as the centre of gravity formed by the above-mentioned asymmetric forces.

According to an embodiment of the invention, the ports comprise a first inlet port and a first outlet port for the first medium, which communicate with the first plate interspaces and are provided on a first side of the centre axis, and a second inlet port and a sec- ond outlet port for the second medium, which communicate with the second plate interspaces and are provided on the second side of the centre axis. Advantageously the common centre of gravity may then be located on the second side of the centre axis.

According to a further embodiment of the invention, the attachment members consist of a first attachment member and a second attachment member, wherein these two attachment mem- bers both may be positioned on the second side. For certain, especially relatively small, plate heat exchangers it is sufficient if the plate package has two attachment members along the short sides, i.e. merely two attachment points. For such a plate heat exchanger it is advantageous if both the attachment points are located on the side where the working pressure is the highest.

According to a further embodiment of the invention, the attachment members consist of a first attachment member and two second attachment members, wherein at least the first attachment member and one of the second attachment members are positioned on the second side of the centre axis. For certain plate heat exchangers, at least three attachment points are required, wherein at least two of these advantageously are located on the side where the working pressure is the highest.

According to a further embodiment of the invention, the attachment members consist of two first attachment members and two second attachment members, wherein at least one of the first attachment members and one of the second attachment members are positioned on the second side of the centre axis. For larger plate heat exchangers, at least four attachment points are required, wherein at least two of these advantageously are located on the side where the working pressure is the highest. According to a further embodiment of the invention, the attachment members are designed as attachment tabs extending outwardly from the frame plate. These attachment tabs may then extend in parallel with the main extension plane of the frame plate. One or several of the attachment tabs may advantageously be provided with a hole for receiving an attachment element such as a screw.

According to a further embodiment of the invention, the first plate interspaces and the second plate interspaces are provided in an alternating order in the plate package, wherein the plate interspace, which is located most closely to the frame plate is a first plate interspace. The plate interspace located most closely to the frame plate is thus a plate interspace with a relatively low working pressure. Such an arrangement is advantageous from a thermal point of view.

According to a further embodiment of the invention, the frame plate, the heat exchanger plates and the pressure plate are permanently joined to each other.

According to a further embodiment of the invention, the plate heat exchanger comprises a connection member having an abutment surface abutting the frame plate of the plate package and comprising four connecting conduits located opposite to a respective one of the four ports. Advantageously, the connecting member may comprise a number of attachments that are arranged to be in engagement with a respective one of the attachment members for attachment of the plate package to the abutment surface.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is now to be explained more closely by means of a description of various embodiments and with reference to the drawings attached hereto. Fig. 1 discloses a side view of a plate heat exchanger according to a first embodiment of the invention.

Fig. 2 discloses a perspective view towards a frame plate of a plate heat exchanger in Fig. 1. Fig. 3 discloses a perspective view towards a pressure plate of the plate heat exchanger in Fig. 1.

Fig. 4 discloses a perspective view towards a frame plate of a plate heat exchanger according to a second embodiment of the invention. Fig. 5 discloses a perspective view towards a pressure plate of the plate heat exchanger in Fig. 4.

Fig. 6 discloses a perspective view towards a frame plate of a plate heat exchanger according to a first embodiment of the invention. Fig. 7 discloses a perspective view towards a pressure plate of the plate heat exchanger in Fig. 6.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS OF THE INVENTION

Figs. 1 -3 disclose a side view of a plate heat exchanger comprising a plate package 1 with a frame plate 2, a plurality of heat exchanger plates 3 and a pressure plate 4. The plates 2, 3. 4 extend substantially in parallel to a main extension plane p. The frame plate 2 and the pressure plate 4 are provided on a respective side of the heat exchanger plates 3. In the embodiments disclosed, the frame plate 2, all heat exchanger plates 3 and the pressure plate 4 are permanently joined to each other, for instance by means of brazing, gluing, welding or the like.

The heat exchanger plates 3 in the plate package 1 form a plurality of plate interspaces comprising first plate interspaces 5 for a first medium and second plate interspaces 6 for a second medium. The plate interspaces 5, 6 are provided in an alternating order in the plate package 1 in such a way that every second plate interspace is a second plate interspace 6 and the remain- ing plate interspaces are first plate interspaces 5. In the embodiments disclosed, the plate interspace located most closely to the frame plate 2 is a first plate interspace 5, see Fig. 1 .

The first plate interspaces 5 are arranged to receive a first medium having a relatively low first working pressure. The second plate interspaces 6 are arranged to receive a second medium having a relatively high second working pressure. The plate heat exchanger disclosed is suitable for being provided in an appa- ratus for heating of hot-water. In such an application, the first plate interspaces 5 may receive and convey a first medium, in this case a primary medium for heating of a second medium which then is a secondary medium in the form of tap hot-water, which is received and conveyed through the second plate inter- spaces 6. In a typical case, the working pressure of the primary medium in the first plate interspaces 5 may be 2-4 bars, for instance approximately 3 bars, whereas the working pressure of the secondary medium in the second plate interspaces 6 may be 8-12 bars, for instance approximately 10 bars.

The plate package 1 has two opposite short sides 1 a and 1 b, and two opposite long sides 1 c and 1 d, see Fig. 3. The plate package 1 defines a longitudinal centre axis x, which extends centrally along the frame plate 2 in parallel with or substantially in parallel with the two long sides 1 c and 1 d. The plate package

I has, seen in a direction towards the frame plate 2, a first side with regard to the centre axis x and a second side 16 with regard to the centre axis x.

The frame plate 2 and each of the heat exchanger plates 3 have four portholes, which form four ports 1 1 , 12, 13 and 14 that extend through the frame plate 2 and the heat exchanger plates 3. The ports 1 1 -14 comprise a first inlet port 1 1 and a first outlet port 12 for the first medium, and a second inlet port 13 and a second outlet port 14 for the second medium. The first inlet port

I I and the first outlet port 12 communicate with the first plate interspaces 5 and are provided on the first side 15 of the centre axis x. The second inlet port 13 and the second outlet port 14 communicate with the second plate interspaces 6 and are provided on the second side16 of the centre axis x. In the embodi- ments disclosed, the two media thus flow in parallel to each other, but in opposite directions, see Figs. 2 and 4, or in the same direction, see Fig. 6.

In the embodiments disclosed, the ports 1 1 -14 are symmetric with respect to the centre axis x, which means that the ports 1 1 and 12 on the first side 15 are located at the same absolute distance from the centre axis x as the ports 13 and 14 on the second side 16.

The plate heat exchanger comprises or co-operates with a connecting member 18 having an abutment surface 19 abutting the frame plate 2 of the plate package 1 in a mounted position when the plate package 1 is ready to be used. The connecting member 18 comprises four connecting conduits 21 , 22, 23 and 24, which are located opposite to a respective one of the four ports 1 1 -14 in the mounted position. Each connecting conduit 21-24 has an orifice in the abutment surface 19. Each such orifice is surrounded by a gasket 25, sealing the transition between the respective ports 1 1 -14 and 21 -24 in the mounted position. It is to be noted that the connecting member 18 may belong to the plate heat exchanger or the apparatus on which the plate package 1 is to be provided.

The plate package 1 comprises one or several first attachment members 30 which are located at a first of the short sides 1 a, and one or several second attachment members 40 which are located at the second short side 1 b. The attachment members 30, 40 are in the embodiments disclosed, comprised by the frame plate 2, but may for instance also be provided on any other plate, for instance on a strengthening plate provided outside the frame plate 2. The attachment members 30, 40 are po- sitioned in relation to the centre axis x and the ports 1 1 -14 in such a manner that forces caused by the difference between the first working pressure and the second working pressure are balanced.

The attachment members 30, 40 are designed as attachment tabs extending outwardly from the frame plate 2. Such attachment tabs may advantageously constitute an integrated part of the frame plate 2, or more precisely of the sheet forming the frame plate 2. The attachment members 30, 40 may of course have another shape than the one disclosed, and for instance comprise a wider sheet than the tabs disclosed. The attachment members 30, 40 are arranged to be in engagement with corresponding attachments 46 of the connecting member 18 in the mounted position.

In the embodiments disclosed, each attachment member 30, 40 comprises a hole 45 for receiving a screw (not disclosed) which is intended to extend through the hole 45 and into a preferably threaded hole forming the above-mentioned attachment 46 of the connecting member 18. The holes 45 of the attachment members 30, 40 are thus located opposite to the corresponding holes of the attachments 46 of the connecting member 18. It is to be noted that the attachment members 30, 40 for instance may be formed by a respective sheet extending along the whole respective short side 1 a, 1 b with holes provided in corresponding positions as in the embodiments disclosed. It is also to be noted that one or several of the attachment members 30, 40 may lack holes and be intended to be inserted, for instance, into corresponding pockets, grooves, recesses or the like in the connecting member 18.

In the first embodiment disclosed in Figs. 2 and 3, the attachment members comprise or consist of one single first attachment member 30 at the first short side 1 a, and one single second attachment member 40 at the second short side 1 b. Both the at- tachment members 30, 40 are then positioned on the second side 16 of the centre axis x, i.e. the side comprising the ports 13 and 14 for the second medium with the higher working pressure. In this embodiment, the moment around the attachment mem- bers 30, 40 should more specifically be as small as possible in order to reduόe the risk of leakage, which means that the two attachment members 30, 40 are to be positioned at the same distance from the centre line x, for instance between the centre line x and the centre points of the ports 13, 14, and in an ex- treme case the attachment members 30, 40 are positioned to be aligned with the centre points of the ports 13, 14.

In the second embodiment disclosed in Figs. 4 and 5, the attachment members comprise or consist of one single first at- tachment member 30 at the first short side 1 a and two second attachment members 40 at the second short side 1 b. The first attachment member 30 and one of the second attachment members 40 are then positioned on the second side 16 of the centre axis x, i.e. the side comprising the ports 13 and 14 for the sec- ond medium with the higher working pressure. In this case, the attachment members 30, 40 should be displaced towards the second side 16, wherein the two attachment members located on the second side 16 should be located between the centre line x and the centre points of the ports 13, 14. Preferably, all angles of the triangle formed by the attachment members 30, 40 are smaller than or equal to 90°.

In the third embodiment disclosed in Figs. 6 and 7, the attachment members comprise or consist of two first attachment mem- bers 30 and two second attachment members 40. One of the first attachment members 30 and one of the second attachment members 40 are then positioned on the second side 16 of the centre axis x. The attachment members 30, 40 are positioned in such a manner that the attachment members 30, 40 on the sec- ond side 16 of the centre axis x are located at a greater distance from the centre axis x than the attachment members 30, 40 on the first side 15 of the centre axis x. Suitably, one of the attachment members 30, 40 is located along each short side 1 a, 1 b on a respective side of the centre axis x. All attachment members 30, 40 are suitably located at an absolute distance from the centre line x which is less or equal to the distance from the centre line to the ports 1 1 , 12 and 13, 14, respectively.

Common for all the embodiments disclosed is that all, i.e. one or several, of the first attachment members 30 and all, i.e. one or several, of the second attachment members 40 have a common geometric centre of gravity 50, which is located on the second side 16 of the centre axis x, i.e. on the side comprising the ports 13 and 14 for the second medium with the higher working pressure. In such a manner, the above-mentioned balancing of the pressure difference between the working pressures is achieved. All attachment members 30, 40 thus form a geometric figure, which in the examples disclosed is a straight line, see Fig. 2, a triangle, see Fig. 4, or a rectangle, see Fig. 6. In the cases that the attachment members 30, 40 form a geometric figure in the form of a straight line or a rectangle, the centre of gravity 50 is also the centre of the geometric figure, i.e. the absolute distance from the centre to each of the attachment members 30, 40 is equal. It is to be noted that the plate package 1 of course may comprise several attachment members 30, 40 and/or attachment members 30, 40 which form other geometric figures than the ones disclosed herein.

It is to be noted that with the positioning of the attachment members 30, 40 is intended in this application the position of the attachment members 30, 40 in the extension plane p. More precisely, it is referred to a position for a point of each attachment members 30, 40 in which the attachment forces of the attachment member are concentrated. The position of the attachment members 30, 40 in depth, i.e. perpendicular to the extension plane p, may vary, wherein the attachments 46 of the connecting member are positioned in correspondence with such a position of the attachment members 30, 40. The attachment members 30, 40 may have a plane extension as in the embodiments described above, but also a curved or angled extension for engagement with the attachments 46. The attachment members 30, 40 may then be connected to the plate package 1 at a distance from the frame plate 2.

The invention is not limited to the embodiments disclosed, but may be varied and modified within the scope of the following claims. In the embodiments disclosed, the ports are as mentioned above symmetric with respect to the centre axis x. Within the scope of the invention it is possible to permit at least a certain asymmetry in this respect with the definition that the above mentioned centre of gravity is to be located on the second side of the centre axis x. In any case, the attachment members 30, 40 should also then be positioned in relation to the centre axis x and the ports 1 1 -14 in such a manner that the above-mentioned asymmetric forces are balanced.

Claims

1. 1. A plate heat exchanger comprising a plate package (1 ) 5 having a frame plate (2), a pressure plate (4) and a plurality of heat exchanger plates (3) which are provided between the frame plate (2) and the pressure plate (4), wherein the plate package (1 ) has two opposite short sides (1 a, 1 b) and two opposite long sides (1 c, 1 d) and defines a longitu-

10 dinal centre axis (x) which extends centrally along the frame plate (2), wherein the heat exchanger plates (3) are provided beside each other and form a number of plate interspaces (5, 6) which comprise first plate interspaces (5), arranged to receive a first me-

15 dium with a relatively low first working pressure, and second plate interspaces (6), arranged to receive a second medium with a relatively high second working pressure, wherein the frame plate (2) and each of the heat exchanger plates (3) have four portholes which form four ports (1 1 -14) ex-

20 tending through the frame plate (2) and the heat exchanger plates (3), and wherein the plate package (1 ) comprises one or several first attachment members (30, 40) which are located at the first short side (1 a), and one or several second attachment members (40)

25 which are located at the second short side (1 b), characterised in that the attachment members (30, 40) are positioned in relation to the centre axis (x) and the ports (1 1-14) in such a manner that the forces caused by the difference between the first working pressure and the second working pressure are

30 balanced, wherein all one or several first attachment members (30) and all one or several second attachment members (40) have a common centre of gravity (50) located beside the centre axis (x).

35 2. A plate heat exchanger according to claim 1 , wherein the ports comprise a first inlet port (1 1 ) and a first outlet port (12) for the first medium, which communicate with the first plate interspaces (5) and are provided on a first side (15) of the centre axis (x), and a second inlet port (13) and a second outlet port (14) for the second medium, which communicate with the second plate interspaces (6) and are provided on the second side (16) of the centre axis (x).

3. A plate heat exchanger according to claim 2, wherein the common centre of gravity (50) which is located on the second side (16) of the centre axis (x).

4. A plate heat exchanger according to any one of claims 2 and 3, wherein the attachment members consist of a first at= tachment member (30) and a second attachment member (40).

5. A plate heat exchanger according to any one of claims 2 to 4, wherein the attachment members (30, 40) are positioned on the second side (16) of the centre axis (x).

6. A plate heat exchanger according to any one of claims 2 to 4, wherein the attachment members consist of a first attachment member (30) and two second attachment members (40), wherein at least the first attachment member (30) and one of the second attachment members (40) are positioned on the second side (16) of the centre axis (x).

7. A plate heat exchanger according to any one of claims 2 to 4, wherein the attachment members consist of two first attach- ment members (30) and two second attachment members (40), wherein at least one of the first attachment members (30) and one of the second attachment members (40) are positioned on the second side (16) of the centre axis (x).

8. A plate heat exchanger according to any one of the preceding claims, wherein the attachment members (30,40) are de- signed as attachment tabs extending outwardly from the frame plate (2).

9. A plate heat exchanger according to any one of the pre- ceding claims, wherein the first plate interspaces (5) and the second plate interspaces (6) are provided in an alternating order in the plate package (1 ), wherein the plate interspace which is located most closely to the frame plate is a first place interspace (5).

10. A plate heat exchanger according to any one of the preceding claims, wherein the frame plate (2), the heat exchanger plates (3) and the pressure plate (4) are permanently joined to each other.

11. A plate heat exchanger according to any one of the preceding claims, comprising a connecting member (18) with an abutment surface (19), which abuts the frame plate (2) of the plate package (1 ) and comprises four connecting conduits (21 - 24) which are located opposite to a respective one of the four ports (1 1 -14).

12. A plate heat exchanger according to claim 1 1 , wherein the connecting member (18) comprises a number of attachments (46) which are arranged to be in engagement with a respective one of the attachment members (30, 40) for attachment of the plate package (1 ) to the abutment surface (19).