Plate heat exchanger condenser-evaporator and process for low-temperature air separation

Abstract

A plate heat exchanger condenser-evaporator with a heat-exchanger block having a number of heat-exchanger plates with fluid-conducting structures. The heat-exchanger block includes first and second outer surface opposite each other, and third and fourth outer surface opposite each other. The fluid-conducting structures of first heat-exchanger plates have first and second openings not covered by fluid feed or fluid-collecting lines. The fluid-conducting structures of second heat-exchanger plates run between a fluid feed line and a fluid-collecting line each arranged on the heat-exchanger block. The fluid feed line may be on the first outer surface with first openings of the fluid-conducting structures of the first heat-exchanger plates in a region of the first outer surface not covered by the fluid feed line or in a first region of the third outer surface and fourth outer surface. A process for low-temperature air separation is also described.

1 . Plate heat exchanger condenser-evaporator having a heat-exchanger block which comprises a number of heat-exchanger plates having fluid-conducting structures, wherein the heat-exchanger block comprises a first outer surface, a second outer surface opposite the first outer surface, a third outer surface and a fourth outer surface opposite the third outer surface, wherein the fluid-conducting structures of first heat-exchanger plates comprise first and second openings on the heat-exchanger block, which openings are not covered by fluid feed lines or by fluid-collecting lines, and wherein the fluid-conducting structures of second heat-exchanger plates run between a fluid feed line arranged on the heat-exchanger block and a fluid-collecting line arranged on the heat-exchanger block, characterized in that the fluid feed line is arranged on the first outer surface and in that the first openings of the fluid-conducting structures of the first heat-exchanger plates are arranged either in a region of the first outer surface that is not covered by the fluid feed line or in a first region of the third outer surface and a first region of the fourth outer surface. 
     
     
         2 . Plate heat exchanger condenser-evaporator according to  claim 1 , in which the first openings of the fluid-conducting structures of the first heat-exchanger plates are formed by fluid-collecting structures that are connected to heat-transfer fins in a central region of the fluid-conducting structures. 
     
     
         3 . Plate heat exchanger condenser-evaporator according to  claim 2 , in which the fluid feed line runs in a central region of the first outer surface at right angles to the heat-exchanger plates. 
     
     
         4 . Plate heat exchanger condenser-evaporator according to  claim 2 , in which the fluid-collecting structures of the first heat-exchanger plates are constructed as double-exit distributors. 
     
     
         5 . Plate heat exchanger condenser-evaporator according to  claim 1 , in which the fluid-conducting structures of the second heat-exchanger plates comprise openings on the first outer surface, which openings open out into the fluid feed line and are formed by fluid-distribution structures that are connected to heat-transfer fins in a central region of the fluid-conducting structures. 
     
     
         6 . Plate heat exchanger condenser-evaporator according to  claim 5 , in which the fluid-distribution structures of the second heat-exchanger plates are constructed as central distributors. 
     
     
         7 . Plate heat exchanger condenser-evaporator according to  claim 1 , in which the fluid collecting line is arranged on the second outer surface. 
     
     
         8 . Plate heat exchanger condenser-evaporator according to  claim 7 , in which the second openings of the fluid-conducting structures of the first heat-exchanger plates are formed by fluid-distribution structures that are connected to the heat-transfer fins in the central region of the fluid-conducting structures, wherein the second openings formed by the fluid-distribution structures are either arranged in a region of the second outer surface that is not covered by the fluid-collecting line, or are respectively arranged in a second region of the third outer surface and a second region of the fourth outer surface. 
     
     
         9 . Plate heat exchanger condenser-evaporator according to  claim 8 , in which the fluid-collecting line runs in a central region of the second outer surface at right angles to the heat-exchanger plates. 
     
     
         10 . Plate heat exchanger condenser-evaporator according to  claim 8 , in which the fluid-distribution structures of the first heat-exchanger plates are constructed as double-entry distributors. 
     
     
         11 . Plate heat exchanger condenser-evaporator according to  claim 8 , in which the fluid-conducting structures of the second heat-exchanger plates on the second outer surface comprise openings that open out into the fluid-collecting line and are formed by fluid-collecting structures that are connected to the heat-transfer fins in the central region of the fluid-conducting structures. 
     
     
         12 . Plate heat exchanger condenser-evaporator according to  claim 11 , in which the fluid-collecting structures of the second heat-exchanger plates are constructed as central distributors. 
     
     
         13 . Process for low-temperature air separation, in which an oxygen-enriched sump product and a nitrogen-enriched overhead product are generated using compressed, cooled feed air in a first distillation column, and an oxygen-rich sump product and a nitrogen-rich overhead product are generated in a second distillation column, using the oxygen-enriched sump product from the first distillation column, characterized in that the process uses a plate heat exchanger condenser-evaporator having a heat-exchanger block which comprises a number of heat-exchanger plates having fluid-conducting structures, wherein the heat-exchanger block comprises a first outer surface, a second outer surface opposite the first outer surface, a third outer surface and a fourth outer surface opposite the third outer surface, wherein the fluid-conducting structures of first heat-exchange plates comprise first and second openings on the heat-exchanger block, which openings are not covered by fluid feed lines or by fluid-collecting lines, and wherein the fluid-conducting structures of second heat-exchanger plates run between a fluid feed line arranged on the heat-exchanger block and a fluid-collecting line arranged on the heat-exchanger block, wherein the fluid feed line is arranged on the first outer surface and in that the first openings of the fluid-conducting structures of the first heat-exchanger plates are arranged either in a region of the first outer surface that is not covered by the fluid feed line or in a first region of the third outer surface and a first region of the fourth outer surface. 
     
     
         14 . Process according to  claim 13 , in which by means of the, or one of the, plate heat exchanger condenser-evaporators, the oxygen-rich sump product of the second distillation column is partially evaporated in the fluid-conducting structures of the first heat-exchanger plates, and in which the nitrogen-enriched overhead product of the first distillation column is partially liquefied in the fluid-conducting structures of the second heat-exchanger plates. 
     
     
         15 . Process according to  claim 13 , in which a fluid is withdrawn from the second distillation column and fed into a third distillation column, wherein the third distillation column comprises an overhead condenser in which, by means of the, or one of the, plate heat exchanger condenser-evaporators, a part of the oxygen-enriched sump product of the first distillation column is partially evaporated in the liquid-conducting structures of the first heat-exchanger plates, and in which an argon-enriched overhead product of the third distillation column is partially liquefied in the fluid-conducting structures of the second heat-exchanger plates.