PLATE HEAT EXCHANGER

Abstract: Plate heat exchanger having mainly rectangular plates mounted in a frame. According to the invention the plates (6, 8) are arranged in at least two groups, the plates having port holes of one size being arranged in one group, while plates having port holes of another size are arranged in another group, the plate group having the largest port holes being arranged closest to the inlet (3) while a plate groupe having smaller port holes (9) is arranged further away from the inlet (3).

Description: Plate heat exchanger This invention relates to a heat exchanger comprising several pla¬ tes mounted in a frame and mainly rectangular, which plates are tightened from each other and between which heat transfer areas in the form of heat exchanging passages are formed for through-flow of heat exchanging media, of which at least one is conducted to and from the heat exchanger via inlets and outlets arranged at one of its ends, the plates at their corner parts being provided with openings for forming of inlet and outlet channels. Such plate heat exchangers are manufactured in different sizes ha¬ ving plates the heat transfer areas of which can range from some .few square decimetres to several square metres. The plate material is chosen with regard to the field of use but usually comprises stainless or acid-resistant steel. For certain purposes titanium is used, which has excellent resistance against salt water but is very expensive. Plate heat exchangers for large flows require inlet and outlet channels having large through-flow areas, i.e. large openings in the corner parts of the plates. That means that large parts of the plates have to be stamped away in order to get these large ope- nings. Particularly in those cases when titanium is used that means that expensive material is stamped away. In the inlet ports of the plates the flow is normally branched off for flowing through parallel-connected heat exchanging passages. Due to this fact the flow is reduced in size with the distance from the inlet. This fact means that seen from a theoretical point of view the port holes of the plates could be made smaller and smaller when the distance between the plates and the inlet becomes greater and greater. OMPI If the port parts of the plates could be made smaller the useful heat transfer area could be made larger within the same raw sheet- metal size. In practice, however, it is not possible to arrange plates provided with port holes becoming smaller and smaller. Firstly, It would mean that It would be necessary for a plate heat exchanger supplier to have a very great number of plates In stock, which is not economically justifiable. Secondly, It would be ne¬ cessary to have many expensive press tools. Thus, there is a need In the market of a plate heat exchanger in which at least certain plates are provided with port-holes, which are smaller than those of the plates closest to the Inlet. At the same time such a heat exchanger partly has to be economically jus¬ tifiable, partly has to function satisfyingly. By giving the heat exchanger such a design that is mentioned in the claims the existing needs can be filled. According to a preferred embodiment the heat exchanger is provided with two groups of plates, the plates in one group having port ho¬ les mainly of one and the same size, while the plates In the se¬ cond group have port holes of another size, which is mainly one and the same. The placing of the groups shall be such that the group of plates provided with the large port holes are placed do— sest to the connections of the frame plate. The groups are prefer¬ ably separated by means of a separation plate arranged preferably by means of gaskets to tighten against the plates of respective groups. The invention shall In the following be described more in detail with reference to the accompanying figures, of which figure 1 shows a side view of a heat exchanger according to the invention having two groups of platesj figures 2a and 2b show plan view of the corner parts of two plates having large and small openings, respectively; figure 3 shows a plan view of the corner part of a plate having a large opening put on a separation plate with a plate having a smaller opening Indicated beneath; figures 4a and 4b schematically show plan views of parts of plates having small and large openings, respectively, and corresponding heat transfer areas; and figure 5 shows a vertical, longitudinal section of a separa¬ tion plate with plate groups having large and small openings, res¬ pectively, indicated in the corner parts. In figure 1 Is by 1 Indicated a frame comprising a frame plate 2 having an Inlet 3 and an outlet 4, and a pressure plate 5. In the frame partly a group of plates 6 having large openings 7 in the corner parts and partly a group of plates 8 having smaller ope- nings 9 in the corner parts are mounted. The groups are separated by a separation plate 10. The corner parts of the plates 6, 8 are shown in figure 2, the openings 7 and 9, respectively, being surrounded by ring gaskets 11, 12. The outer edge measure a outside the gaskets 11, 12 decide the position of the openings 7, 9 in the plates. In figure 3 is shown that the openings 7, 9 in the corner parts of plates in two adjacent groups are not concentric since the posi- tion of the openings are decided by the outer edge measure a ac¬ cording to figure 2. In the figure an edge gasket is indicated by 13. This one is connected with the mentioned gasket 11. The edge of the opening 9 is indicated by 14 and the edge of the opening of the separation plate by 15. This opening 15 has in the figure of clarity reasons been made somewhat smaller than the opening 14 but Is In reality mainly of the same size as is that one. The opening 15 is placed such that smallest possible flow resistance arises In the flow from the channel formed by the openings 7 to the channel formed by the openings 9, and vice versa, when the medium is flo¬ wing out of the heat exchanger. When the openings of a plate are small, the heat transfer area can be made large, i.e. a larger part of the plate is utilized, which Is illustrated in the figures 4a and 4b. In this connection the positions of the edge and the ring gaskets on the plate are changed which means that if the port holes are made small the position of the gasket is moved further upwards on the plate. This means that the plate gets a larger heat transfer area compared with the situation when the plate is provi¬ ded with large port holes. It Is apparent from figure 5 how the gasket against the separation plate between two adjacent plate groups is arranged. The gasket 11 directly tightens against the plane separation plate, while the gasket 12 engages a circular groove in the separation plate. The invention Is, of course, not limited to a heat exchanger ha- vlng two grups of plates but three or more groups can be found. The essential thing is that the plates In each group are provided with port holes mainly of the same size. Due to the great costs for manufacturing a new heat exchanger plate it is necessary from an economic point of .view to use stan¬ dard plates from already existing manufacturing programs when choosing plates having large and small openings, respectively. Thus, it is only necessary to manufacture a new separation plate in order to get a heat exchanger having optimum flowing and heat transfer characteristics. In order to get a good economic effect the plates of the different plate groups shall be essentially different from each other regar¬ ding port size and therewith heat exchanger area, while the outer dimensions are the same. Thus, the large port in two groups-heat exchangers ought to be at least 50 ; % but not more than 100 % lar¬ ger than Is the small port. Further, the number of plates having small ports ought to amount to at least the half of but not more than 2/3 of the total number of plates. OMP The total effect of the invention is then that a heat exchanger Is received which has the good economy of a heat exchanger having plates provided with small ports but having a capacity correspon¬ ding to the connection dimension of the large port in the plate group being closest to the inlet.

Claims: Claims 1. Heat exchanger comprising several plates mounted In a frame and mainly rectangular, which plates are tightened from each other and between which heat transfer areas In the form of heat exchang¬ ing passages are formed for through-flow of heat exchanging media, of which at least one is conducted to and from the heat exchanger via inlets and outlets arranged at one of Its ends, the plates at their corner parts being provided with openings for forming of in- let and outlet channels, c h a r a c t e r i z e d i n that the plates (6, 8) have mainly the same width and length and are arranged in at least two groups, one group comprising plates (6) having port holes (7) mainly of one and the same size, while an¬ other group comprises plates (8) having port holes (9) mainly of one and the same size but different from that of the port holes (7) of the plates (6) of the first group, and the plates (6, 8) having a gasket position which is dependent on the size of the port holes (7, 9), whereby plates (8) having a small port hole (9) have a larger heat transfer area than plates (6), having a larger port hole (7), and that the plate group having the largest port holes (7) Is arranged closest to the inlet (3), while a plate group having smaller port holes (9) is arranged further away from the inlet (3). 2. Heat exchanger according to claim 1, c h a r a c t e r i ¬ z e d i n that the number of groups are two and that the groups are separated from each other by a separation plate (10), which is arranged to tighten against the plates (6, 8) in respec¬ tive group by means of gaskets (11, 12). 3. Heat exchanger according to claim 1 or 2, c h a r a c ¬ t e r i z e d i n that the port holes In the plate group closest to the inlet are at least 50 % but not more than 100 % larger than are the port holes In a plate group placed further away from the inlet. 4. Heat exchanger according to anyone of the preceding claims, c h a r a c t e r i z e d i n that the number of plates ha¬ ving a small port hole is at least 1/2 but not more than 2/3 of the total number of plates.

Inventors: DAHLGREN JOENS ARTHUR, DAHLGREN, JOENS, ARTHUR
Applicants: ALFA LAVAL AB, ALFA-LAVAL AB
Application year: 1982
Main classification: F28F13
IPC codes: F28D9, F28F3