WO2008140390A1

WO2008140390A1 - Plate heat exchanger

Info

Publication number: WO2008140390A1
Application number: PCT/SE2008/050384
Authority: WO
Inventors: Thord Gudmundsson
Original assignee: Alfa Laval Corporate Ab
Priority date: 2007-05-10
Filing date: 2008-04-03
Publication date: 2008-11-20
Also published as: DE112008001056T5; CN101675314A; CN101675314B; SE0701118L; DE112008001056B4; SE532084C2

Abstract

The invention relates to a plate heat exchanger. A plate heat exchanger (1) including a plate stack (2) with twoendplates (3, 4) and number of heat exchanger plates (5), which are arranged between the endplates (3, 4), wherein oneendplate (3, 4 )is provided with attachment means (6) extending outside the plate stack (2). It is further is provided with ports on the one end plate (3, 4) that corresponds to connections (10) on a mounting location (9) whereupon the plate heat exchanger (1) is to be mounted. The longitudinal extensionof the attachment means (6) deviates in relation to the longitudinal extensionof the rest of the endplate (3, 4) and the plate stack (2).

Description

PLATE HEAT EXCHANGER

BACKGROUND OF THE INVENTION

The present invention relates to a plate heat exchanger, and more specifically to an arrangement of the end plate of a plate heat exchanger.

BACKGROUND OF THE INVENTION

Plate heat exchangers that mounted on hydro blocks or similar needs to have an end plate of high strength since the pressure of the system can be very high. As more and more plate heat exchangers are provided with attachment means arranged outside the heat exchanger, see e.g. US-A1 -2005/0121182, the require- ment of the strength is even higher. The pressure almost causes the end plate and the heat exchangers to be lifted or separated from its mounting position, which might cause a leakage in the connection. A bending moment is created in the attachment means. As the plates in this type of plate heat exchangers are brazed or soldered together, all the plates including the end plate are exposed to a heat treatment during the soldering process that makes the material of the end plate to partly loose its original cold formed strength.

US-A1 -2005/0121182 discloses a heat exchanger, including a plurality of heat-transfer plates stacked onto one another to define alternating channels, a mounting plate soldered on one side to a side of the stacked plates and adapted to mount on its opposite side to a separate component.

SUMMARY OF THE INVENTION

The object of this invention is to remedy the problems mentioned above. More precisely, the object is to provide a plate heat exchanger provided with a frame plate offering improved possibilities to attach the plate heat exchanger to a hydro block or similar, said frame plate designed to have a high strength preventing the plate heat exchanger or the frame plate thereof from breakage during a high pressure load, and thereby causing a leakage in the connection between the plate heat exchanger and the hydro block or similar. This object is achieved by the plate heat exchanger initially defined, which is characterized in that a longitudinal extension of the attachment means deviates in relation to the longitudinal extension of the rest of the end plate and the plate stack.

By providing the frame plate of the plate heat exchanger with bended attachment means, the strength is increased while mounting the end plate onto the hydro block or similar. The attachment means are bended while mounting so that the mounting means reaches the surface of the hydro block or similar. The bending of the attachment means creates stress and in some cases also plastic or permanent deformation in the transition area between the attachment means and the stack of heat exchanger plates. The deformation achieves a strain hardening at the most exposed location, which increases the strength and the stress so that the end plate not fails during load. Thereby the sealing or gaskets between the end plate and the hydro block are kept in place.

According to another aspect of the invention, the attachment means are formed as brackets extending from the end plate, and that the attachment means are arranged asymmetrically on the short sides of the end plate.

According to yet another aspect of the invention, one attachment means are arranged asymmetrically on each of short sides of the end plate.

According to still another aspect of the invention, the attachment means are provided with holes for mounting the plate heat exchanger to a mounting location.

Further aspects of the invention are defined in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

In the following, the invention will be explained more with reference to the accompanying drawings, where: Fig. 1 discloses schematically a side view of a plate heat exchanger according to the invention;

Fig. 2 discloses schematically a perspective view of a plate heat exchanger according to the invention;

Fig. 3 discloses schematically a perspective view of a plate heat exchanger according to the invention and mounting block;

Fig. 4 discloses schematically a partial detailed perspective view of the plate heat exchanger according to the invention and the mounting block; and Fig. 5 discloses schematically a partial detailed perspective view of the plate heat exchanger according to the invention being mounted on a mounting block.

DETAILED DESCRIPTION OF EMBODIMENTS

Figs. 1 to 5 disclose different views of a plate heat exchanger according to the invention. The plate heat exchanger 1 includes a number of heat exchanger plates 5, which are arranged beside each other to form a plate package or plate stack 2. In Figs. 1-5 the stack of heat exchanger plates 5 has been shown as a uniform package for simplifying the drawing, but in reality the stack comprises several heat exchanger plates 5. A frame plate 3 and a pressure plate 4 are arranged on side of the heat exchanger plates 5. In the shown embodiment the frame plate 3, all heat exchanger plates 5 and a pressure plate 4 are permanently connected to each other, e.g. by brazing, soldering, gluing, welding or any other suitable joining method.. The frame plate 3 and the pressure plate 4 will in the continued description of the invention be named as end plates 3 and 4, respectively. Each heat exchanger plate 5 includes in a manner known per se a corrugation or pattern for increasing the heat transfer. The pattern comprise crests and valleys, which on mutually adjacent heat exchanger plates 5 abut against one another locally so as to constitute contact points which in a known manner are used for connecting the heat exchanger plates 5 to one another during the brazing or soldering together of the plate heat exchanger 1. Flow channels are in a known manner formed between mutually adjacent heat exchanger plates 5 in a plate stack 2 comprising a number of heat exchanger plates 5 stacked on one another. Mutually adjacent flow channels accommodate different media between which there is temperature exchange through the heat transfer surfaces of the heat exchanger plates 5.

The heat exchanger plates 5 includes four port holes for forming a corresponding number of port channels extending through the plate package 2 and being in connection with the flow channels formed between the heat exchanger plates 5. It is to be noted that the plate package 2 may include another number of port channels than the four disclosed in the shown embodiments.

The heat exchanger plates 5, the end plate 3 and the end plate 4 are arranged in such a way that they extend substantially in parallel to a common main extension plane. The heat exchanger plates 5, the end plate 3 and the end plate 4 are substantially manufactured in stainless steel containing chromium. The heat exchanger plates 5 are connected to each other by means of a braze connection. The brazing takes place by means of a braze material based on or containing copper, nickel, iron or silver and possibly any possible flux agent that can contain fluorine. A thin foil or paste of the braze material is positioned in each interspace between the heat exchanger plates 5. Thereafter, the plate package 2 could be compressed.

The plate package 2 may by placed in a closed space (not disclosed), such as a vacuum furnace, during vacuum-like pressure conditions or in a gas atmosphere consisting of a substantially inert gas or a reducing gas, and a desired braze temperature which may be up to about 1100⁰C with copper as braze material and about 1200⁰C with nickel as braze material.

At each short end of the end plate 3 a mounting bracket 6 extends from the end plate 3. The mounting brackets 6 extend beside and parallel to a center line of the end plate 3, i.e. the mounting brackets 6 are located asymmetrically on the short sides of the end plate 3. The mounting brackets 6 can also be mounted in the middle of the short side of the end plate 3, but this is not shown. Likewise is not shown that more than one mounting bracket 6 can be provided on each short side of the end plate 3 or that also the long sides of the end plate 3 can be provided with mounting brackets 6.

The longitudinal extension B of the mounting brackets 6 deviates from the longitudinal extension A of the end plate 3. The deviation between the longitudinal extensions creates a deviation angle α. The deviation angle α is between 1 and 15 degrees, and preferably between 2 and 8 degrees. It is important that the angle α is sufficiently large to create plastic deformation of the mounting bracket 6 or at least to a part of the mounting bracket 6, when the mounting bracket 6 and the plate heat exchanger 1 is mounting to a mounting location or block 9. With a smaller angel α than 2 degrees a plastic deformation of the mounting bracket 6 or at least to a part of the mounting bracket is not achieved and with a greater angle α than 8 degrees the mounting of the plate heat exchanger is problematic and the connection between the plate package 2 and the end plates 3, 4 can break during mounting of the plate heat exchanger to the mounting location 9.

The mounting bracket 6 is provided with holes 8 to attach the plate heat exchanger 1 to a mounting location 9. The plate heat exchanger 1 is attached the mounting location by bolts or similar attachment means. Instead of holes on the mounting bracket 6 it can also be slots 8 that are provided on the mounting bracket 6 to attach to the mounting location 9.

Now the mounting of the plate heat exchanger 1 according to the invention will be described with reference to Figs. 3-5. In Fig. 3 the plate heat exchanger 1 is shown together with a mounting location or block 9, whereupon the plate heat exchanger 1 is to be mounted. The mounting block 9 includes ports or connections 10 that connect to corresponding ports 7 of the plate heat exchanger 1 (see Fig. 2). It also includes mounting holes 11 corresponding to the holes 8 of the plate heat exchanger 1.

To mount the plate heat exchanger 1 onto the block 9, the plate heat exchanger 1 is put in its mounting position so that the ports or connections 10 of the block 9 connect to the corresponding ports 7 of the plate heat exchanger 1. A bolt (not shown) or similar is inserted into the hole 8 of the bracket 6 and further into the hole 11 of the block 9 or in the opposite direction. A nut (not shown) is threaded onto the bolt to tighten the bolt joint so that the plate heat exchanger 1 is tightly mounted onto the block 9. During the tightening of the bolt joint the mounting bracket 6 will be pressed downwards towards the block 9 so that the longitudinal extension of the mounting bracket 6 and the longitudinal extension of the end plate 3 are parallel. The downwards bending of the mounting bracket 6 towards the block 9 creates stress in the mounting bracket 6 and to some extent also plastic deformation in the junction or transition area between the mounting bracket 6 and the end plate 3. The plastic deformation creates increased strength or decreased strain at the same stress in exposed areas and the stress in the mounting bracket 6 prevents the end plate 3 from moving during load so that gaskets between the plate heat exchanger 1 and block 9 are kept in place, and leakage is avoided.

According to another solution (not shown) the block, whereon the plate heat exchanger 1 is to be mounted, is provided with a mounting or attachment arrangement where one bracket of the end plate is inserted into a slot similar, whereas the other bracket is attached to the block with a bolt or similar as described above. After the first bracket has been inserted into the slot or similar holding arrangement the rest of the plate heat exchanger will be pressed downwards and creating plastic deformation in the junction or transition area between the mounting bracket and the end plate of the first bracket. As the plate heat exchanger has been pressed down to be in contact with the block, the second bracket will be tightened by the bolt joint or similar to also creating a plastic deformation of the second bracket.

In the above description the brackets have been shown as being provided on the end plate closest to the mounting block and the port holes, but it could also be possible to in special cases to provide the brackets on the other end plate.

The invention is not limited to the embodiments described above and shown on the drawings, but can be supplemented and modified in any manner within the scope of the invention as defined by the enclosed claims.

Claims

1. A plate heat exchanger (1) including a plate stack (2) with two end plates (3, 4) and number of heat exchanger plates (5), which are arranged between the end plates (3, 4), wherein one end plate (3, 4) is provided with attachment means (6) extending outside the plate stack (2), further that the plate heat exchanger (1 ) is provided with ports (7) on the one end plate (3, 4) that corresponds to connections (10) on a mounting location (9) whereupon the plate heat exchanger (1 ) is to be mounted, c h a r a c t e r i z e d i n t h a t the longitudinal extensions (B) of the attachment means (6) deviates in relation to the longitudinal extension (A) of the rest of the end plate (3, 4) and the plate stack (2), and where the attachment means (6) can be deformed so that the longitudinal extensions (B) of the attachment means (6) are parallel with the longitudinal extension (A) of the end plate (3, 4) and the plate stack (2) when the plate heat exchanger (1 ) being mounted to the mounting location (9), said deformation creating an increased strength of the attachment means (6).

2. A plate heat exchanger (1) according to claim 1 , wherein the attachment means are formed as brackets (6) extending from the end plate (3, 4).

3. A plate heat exchanger (1) according to anyone of claims 1 and 2, wherein the attachment means (6) are arranged asymmetrically on the short sides of the end plate (3, 4).

4. A plate heat exchanger (1) according to anyone of claims 1-3, wherein one attachment means (6) are arranged asymmetrically on each of short sides of the end plate (3, 4).

5. A plate heat exchanger (1 ) according to anyone of claims 1 -4, wherein the attachment means (6) are provided with holes for mounting the plate heat exchanger (1) to the mounting location (9).

6. A plate heat exchanger (1 ) according to anyone of claims 1-4, wherein the attachment means (6) are provided with slots for mounting the plate heat exchanger (1) to the mounting location (9).

7. A plate heat exchanger (1) according to anyone of claims 1-6, wherein longitudinal extension (B) of the attachment means (6) deviates in relation to the longitudinal extension (A) of the rest of the end plate (3, 4), and where the deviation angle (α) is between 1 and 15 degrees, and preferably between 2 and 8 degrees.

8. A plate heat exchanger (1 ) according to anyone of claims 1-6, wherein longitudinal extension (B) of the attachment means (6) deviates in relation to the longitudinal extension (A) of the rest of the end plate (3, 4), and where the deviation angle (α) is sufficiently large to create plastic deformation of at least a part of the attachment means (6), when mounting the plate heat exchanger (1) to the mounting location (9).