Plate heat exchanger

Abstract

A plate heat exchanger comprising a casing, a fluid separation device, a number of heat transfer plates that are permanently joined to each other and have central openings that form a central space in the plate stack and in which the fluid separation device is arranged, such that a first part of the central opening may act as a fluid inlet and a second part of the central opening may act as a fluid outlet for a first fluid, opposite sides of the plates act fluid entries and exits for a second fluid, wherein two end plates have central through holes the ends of the plate stack, each of the end plates being thicker than the heat transfer plates, providing increased mechanical support for the plate stack, and having a slower thermal expansion.

1 . A plate heat exchanger comprising
 a casing that forms an enclosure,   a fluid separation device,   a number of heat transfer plates that are joined to each other to form a plate stack that is arranged within the enclosure and has alternating first and second flow paths for a first fluid and a second fluid in between the heat transfer plates,   the heat transfer plates having
 central openings that form a central space in the plate stack and in which the fluid separation device is arranged, such that a first part of the central opening may act as a fluid inlet and a second part of the central opening may act as a fluid outlet for the first fluid, 
 first sides that act as a fluid entries for the second fluid, and second sides that are opposite the first sides and act as fluid exits for the second fluid, 
   wherein   an end plate that has a central through hole is arranged at a first end of the plate stack,   the end plate being thicker than the heat transfer plates for providing increased mechanical support for the plate stack, the end plate thereby, in response to a change in temperature and due to thermal expansion, expanding slower than the transfer plates.   
     
     
         2 . A plate heat exchanger according to  claim 1 , wherein a thermal expansion catcher is arranged between the end plate and the plate stack. 
     
     
         3 . A plate heat exchanger according to  claim 1 , wherein the expansion catcher comprise a reinforcing heat transfer plate that is thicker than the heat transfer plates and thinner than the end plate. 
     
     
         4 . A plate heat exchanger according to  claim 3 , wherein the expansion catcher comprises a respective additional reinforcing heat transfer plate that is arranged between the reinforcing heat transfer plate and the plate stack, and which is thicker than the heat transfer plates and thinner than the reinforcing heat transfer plate. 
     
     
         5 . A plate heat exchanger according to  claim 2 , wherein the expansion catcher comprises a peripheral lip that extends from the end plate, towards the plate stack and into direct or indirect, via an intermediate element, contact with the plate stack to which the lip is, directly or via the intermediate element, fixedly attached, a groove being located behind the lip for allowing the lip to flex when the heat transfer plates change their volume due to thermal expansion. 
     
     
         6 . A plate heat exchanger according to  claim 5 , wherein the expansion catcher comprises a ring to which the peripheral lip is connected, the ring having a surface that abuts the end plate and is moveable relative the end plate, the ring being directly or via the intermediate element fixedly attached to the plate stack. 
     
     
         7 . A plate heat exchanger according to  claim 2 , wherein the expansion catcher comprises a gasket that is located in a groove that is oriented towards the plate stack. 
     
     
         8 . A plate heat exchanger according to  claim 2 , wherein the expansion catcher comprise a flat plate that is thicker than the heat transfer plates and thinner than the end plate. 
     
     
         9 . A plate heat exchanger according to  claim 1 , wherein the end plate is welded to the plate stack, either directly or via the thermal expansion catcher. 
     
     
         10 . A plate heat exchanger according to  claim 9 , wherein the end plate is welded to the plate stack, either directly or via the thermal expansion catcher, along the central through hole of the end plate. 
     
     
         11 . A plate heat exchanger according to  claim 10 , wherein the thermal expansion catcher catches stresses along a direction that is parallel to a plane of the heat transfer plates, when the heat transfer plates change their volume due to thermal expansion. 
     
     
         12 . A plate heat exchanger according to  claim 1 , wherein a second end plate that has a central through hole is arranged at a second end of the plate stack.