The present invention relates to an arrangement in a plate heat exchanger according to -the pre-characterising clause of claim 1.

A recuperator is already known from the E-C Parsons Goverrunent/Industry Meeting 2 Summary on "Development, Fabrication and Application of a Primary Surface Gas Turbine Recuperator" held in Washington, D.C. on 20-23 May 1985. The flow channels, which have cross-flow and counter-flow sections, connect here via the inlet and exhaust ports with separate manifolds arranged outside the actual set of heat exchanger plates and welded to the set of heat exchanger plates.

Integrating manifolds into the plates by providing the plates with openings with splayed flanges placed around the edge of the openings is already known from DE-A-29 23 944.

When the said plates are joined together into a set of plates, the said flanges telescope into one another to form the walls of the manifolds and indentations in the flanges form inlet and outlet ports of the said manifolds. The object here was to produce a design that is resistant to mechanical stresses and easy to manufacture. No method of controlling the flow into and out of the manifolds is disclosed in the publication.

The object of the present invention is to produce an improved plate heat exchanger of the type described in the pre-characterising clause of claim 1. This is achieved by the combination of characteristic features described in the characterising part of claim 1.

Advantageous embodiments will be seen from the subordinate clauses.

The invention will now be explained in more detail below with reference to the attached drawings in which figure 1 is a perspective view of a plate heat exchanger according to the invention. Figures 2 and 3 show sections through the heat exchanger plates in two different positions, marked in figure 1. Figure 4 shows a perspective view of an alternative embodiment of a plate heat exchanger according to the invention.

In figure 1, 1 generally denotes a plate heat exchanger according to the invention, preferably a recuperator, with flow channels arranged between the plates. Of the said channels every other channel is designed to receive the flow of a heat-emitting medium, in this case exhaust gases from a gas turbine. The direction of flow for these is indicated

in figure 1 by an arrow 2 and the person skilled in the art will appreciate that in order to control the exhaust gas flow a surrounding casing with connections for the inlet and outlet exhaust gas flows is required. The remainder of the flow channels are designed to accommodate the flow of a heat-absorbing medium, in this case compressed air from the gas turbine compressor. The inlet flow from the latter to the recuperator is indicated by an arrow 3 and the outlet flow by an arrow 4.

In order to achieve high efficiency in the transfer of thermal energy from the heat- emitting medium to the heat-absorbing medium the flows will, of course, essentially be in opposite directions. This is the case in a section of the through-flow channels for the heat-absorbing medium, denoted by 5. 6 and 7 respectively indicate sections of the said through-flow channels in which the flows are not in opposite directions, but crossing one another.

The flow 3 of heat-absorbing medium in the recuperator 1 passes via a manifold 8, which connects with the manifold 8 via inlet ports in each flow channel for the heat- absorbing medium. There is a corresponding connection via outlet ports in each flow channel to a manifold 9 for the flow 4 of heat-absorbing medium out of the recuperator.

As will be explained in more detail below, the inlet ports are connected to section 6 of the through-flow channels, whereas the outlet ports are connected to section 7 of the through-flow channels.

With reference to figures 2 and 3, which show sections A-A and B-B respectively of the recuperator in figure 1, the arrangement of the inlet and outlet ports and the manifolds 8, 9 will now be described in more detail. Since the conditions are analogous in the two manifolds, reference will only be made to the construction in connection with the manifold 9 and the said partial sections A-A and B-B illustrated in figures 2 and 3 respectively.

In the plates from which the recuperator is constructed, an opening 9', with side wall 10 running around the edge 9" of the opening 9', is made in one section on two opposing sides a, b. The said side wall is inclined somewhat inwards towards the opening 9'. In a section of the side wall 10 adjoining the section 7 there is an interruption 10'. With the side walls of the plates telescoped in one another as shown in figure 2 and joined pressure-tightly to one another, for example by soldering, the side walls 10 form the walls of the manifold 9 and the interruptions 10' form the outlet ports 10", which

connect the manifold 9 to the through-flow channels for the heat-absorbing medium. In figures 2 and 3 the said through-flow channels are denoted by 11, whilst the flow of the heat-absorbing medium is indicated by arrows 4'. The through-flow channels for the heat-emitting medium are correspondingly indicated by 12.

The interruption 10' is preferably formed in the side wall 10 of each plate in such a way that, as shown diagrammatically in figure 3, the side wall section 10"' corresponding to the interruption 10' is bent so that it forms an angle x with the plane of the plates. The side wall section 10"' is thereby made to form a guide for the flow of heat-absorbing medium through the inlet and outlet ports 10".

Figure 4 shows that the outer walls of the manifolds, as well as the short sides of the recuperator in an alternative embodiment, are bent outwards. The splayed form gives increased strength, which improves the service life of the recuperator.

By arranging the manifolds 8, 9, inlet and outlet ports and the sections 5, 6 and 7 of media flows in opposite directions to one another or crossing one another according to the invention, a compact construction is thus achieved whilst making the recuperator highly efficient and easy to manufacture.