Cryogenic refrigeration of a process medium

Abstract

The present invention pertains to a cryogenic refrigeration system and method for cryogenic refrigeration of a process medium. In particular, the invention relates to a counter flow heat exchanger configuration and pressure regulator arrangement to reduce exergetic losses in the system. Accordingly, a cryogenic refrigeration system is suggested comprising a conduit (2) configured to provide a supply flow (10) of a process medium, a counter flow heat exchanger (3), which is thermally coupled to a heat exchanger section (2A) of the conduit (2) and comprises an inlet (34) at a cold end (30) of the heat exchanger (3) and an outlet (36) at the warm end (32) of the heat exchanger (3), a first pressure regulator (4), which is in fluid communication with the conduit (2) and is arranged downstream of the heat exchanger section (2A), and a vessel (5), which is in fluid communication with the conduit (2) and is arranged downstream of the first pressure regulator (4), wherein the vessel (5) is in fluid communication with the inlet (34) of the heat exchanger (3) and is configured to provide an evaporated gas flow from the process medium to the inlet (34) of the heat exchanger (3). Furthermore, the conduit (2) is free of any evaporation heat exchanger upstream of the heat exchanger section (2A) of the conduit (2).

1 . Cryogenic refrigeration system ( 1 ), comprising:
 a conduit ( 2 ) configured to provide a supply flow ( 10 ) of a process medium;   a counter flow heat exchanger ( 3 ), which is thermally coupled to a heat exchanger section ( 2 A) of the conduit ( 2 ) and comprises an inlet ( 34 ) at a cold end ( 30 ) of the heat exchanger ( 3 ) and an outlet ( 36 ) at the warm end ( 32 ) of the heat exchanger ( 3 );   a first pressure regulator ( 4 ), which is in fluid communication with the conduit ( 2 ) and is arranged downstream of the heat exchanger section ( 2 A); and   a vessel ( 5 ), which is in fluid communication with the conduit ( 2 ) and is arranged downstream of the first pressure regulator ( 4 ), wherein the vessel ( 5 ) is in fluid communication with the inlet ( 34 ) of the heat exchanger ( 3 ) and is configured to provide an evaporated gas flow from the process medium to the inlet ( 34 ) of the heat exchanger ( 3 ),   wherein   the conduit ( 2 ) is free of any evaporation heat exchanger upstream of the heat exchanger section ( 2 A) of the conduit ( 2 ).   
     
     
         2 . Cryogenic refrigeration system ( 1 ) according to  claim 1 , wherein
 the heat exchanger ( 3 ) is configured to provide a temperature factor of the evaporated gas at the warm end ( 32 ) of the heat exchanger ( 3 ) relative to the process medium of the supply flow ( 10 ) at the warm end ( 32 ) of the heat exchanger ( 3 ) larger than 0.9, preferably larger than 0.98, during normal operation of the cryogenic refrigeration system ( 1 ); and/or   the heat exchanger ( 3 ) comprises an NTU configured to match a temperature of the evaporated gas with a temperature of the process medium at the warm end ( 32 ) of the heat exchanger ( 3 ) during normal operation of the cryogenic refrigeration system ( 1 ).   
     
     
         3 . Cryogenic refrigeration system ( 1 ) according to  claim 2 , wherein the temperature factor and/or the NTU is provided by a heat transfer area of the heat exchanger ( 3 ), preferably by a length of the heat exchanger, wherein the heat exchanger ( 3 ) is preferably of a finned tube shape, coiled shape, and/or fin shape and at least partially surrounds a circumference of the conduit ( 2 ). 
     
     
         4 . Cryogenic refrigeration system ( 1 ) according to  claim 1 , wherein that the outlet ( 36 ) of the heat exchanger ( 3 ) is coupled to a recuperation system, a compressor system, a vacuum pump, and/or a liquefaction system, which is configured to provide a constant pressure in the vessel ( 5 ). 
     
     
         5 . Cryogenic refrigeration system ( 1 ) according to  claim 1 , wherein that the process medium provided upstream of the first pressure regulator ( 4 ) is a pressurized liquid, preferably liquid helium or liquid nitrogen, wherein the first pressure regulator ( 4 ) is configured to reduce the pressure of the process medium to provide a two-phase process medium ( 13 ) flow downstream of the first pressure regulator ( 4 ), wherein the first pressure regulator ( 4 ) preferably comprises a valve, expansion valve, and/or turbine. 
     
     
         6 . Cryogenic refrigeration system ( 1 ) according to  claim 5 , wherein the vessel ( 5 ) collects the liquid phase ( 15 ), wherein the vessel ( 5 ) is thermally coupled to a load ( 6 ) or wherein a load ( 6 ) is disposed in the collected liquid phase ( 15 ) of the vessel ( 5 ) to provide an isothermal load ( 6 ). 
     
     
         7 . Cryogenic refrigeration system ( 1 ) according to  claim 6 , wherein the evaporated gas from the process medium is provided by a state of the two-phase process medium ( 13 ) controlled by the pressure regulator ( 4 ), a pressure of the vessel ( 5 ), and the load ( 6 ), wherein the evaporated gas is a sub-atmospheric evaporated gas ( 12 ). 
     
     
         8 . Cryogenic refrigeration system ( 1 ) according to  claim 6 , wherein the system ( 1 ) further comprises a controller ( 7 ) and at least one sensor ( 70 ,  72 ,  74 ,  76 ) in communication with said controller, wherein
 the system ( 1 ) comprises at least one temperature sensor ( 70 ) arranged upstream of the pressure regulator ( 4 ) and downstream of the heat exchanger section ( 2 A), wherein the controller ( 7 ) is configured to control the first pressure regulator ( 4 ) based on the measured value of the at least one temperature sensor ( 70 ) to control the state of the two-phase process medium;   the system ( 1 ) comprises at least one filling sensor ( 72 ) arranged in the vessel ( 5 ) and/or at least one flow sensor ( 76 ) arranged downstream of the pressure regulator ( 4 ) for measuring a mass flow of a liquid phase of the process medium to the load, wherein the controller ( 7 ) is configured to control the pressure regulator ( 4 ) to control the mass flow based on the measured value of the at least one filling sensor ( 72 ) and/or the at least one flow sensor ( 76 ); and/or   the system ( 1 ) comprises at least one pressure sensor ( 74 ) arranged in communication with the vessel ( 5 ) and a compressor system coupled to the outlet ( 36 ) of the heat exchanger ( 3 ), wherein the controller ( 7 ) is configured to control the pressure in the vessel ( 5 ) by controlling the compressor system based on the measured value of the at least one pressure sensor ( 74 ).   
     
     
         9 . Cryogenic refrigeration system ( 1 ) according to  claim 8 , wherein the system ( 1 ) further comprises a control valve ( 20 ) for controlling the mass flow of the supply flow ( 10 ), which is in communication with the controller ( 7 ) and is arranged in parallel to and upstream of the first pressure regulator ( 4 ), wherein the controller ( 7 ) is configured to control the mass flow of the supply flow ( 10 ) via the control valve ( 20 ) based on the measured value of the at least one temperature sensor ( 70 ), filling sensor ( 72 ) and/or flow sensor ( 76 ). 
     
     
         10 . Cryogenic refrigeration system ( 1 ) according to  claim 8 , wherein the system ( 1 ) comprises at least one warm-end temperature sensor ( 70 ) in communication with the conduit ( 2 ) and the outlet ( 36 ) of the heat exchanger ( 3 ) at the warm end ( 32 ) of the heat exchanger ( 3 ), wherein the controller ( 7 ) is configured to adjust the evaporative gas flow based on a temperature difference measured by the at least one warm-end temperature sensor ( 70 ) by controlling the pressure regulator ( 4 ). 
     
     
         11 . Cryogenic refrigeration system ( 1 ) according to  claim 1 , wherein the heat exchanger ( 3 ) is configured as a plurality of heat exchanging modules ( 3 A,  3 B,  3 C), which are arranged in parallel and/or in series to the conduit ( 2 ), wherein preferably a second pressure regulator ( 4 B) in fluid communication with the conduit ( 2 ) is arranged between each serially arranged heat exchanging module ( 3 A,  3 C). 
     
     
         12 . Method for providing a cryogenic refrigeration in a cryogenic refrigeration system ( 1 ), the method comprising:
 providing a supply flow ( 10 ) of a process medium in a conduit;   cooling the supply flow in a counter flow heat exchanger ( 3 );   reducing the pressure of the supply flow ( 10 ) by means of a pressure regulator ( 4 ); and   receiving the supply flow ( 10 ) in a vessel ( 5 ), wherein an evaporated gas flow from the process medium is used by the heat exchanger ( 3 ) to cool the supply flow ( 10 ),   wherein the cooling of the supply flow is provided free of any evaporating liquid phase.   
     
     
         13 . Method according to  claim 12 , characterized in that
 a temperature factor of the evaporated gas at a warm end ( 32 ) of the heat exchanger ( 3 ) relative to the process medium of the supply flow ( 10 ) at the warm end ( 32 ) of the heat exchanger ( 3 ) is provided by the heat exchanger, which is larger than 0.9, preferably larger than 0.98, during normal operation of the cryogenic refrigeration system ( 1 ); and/or   a temperature of the evaporated gas is matched to a temperature of the process medium at a warm end ( 32 ) of the heat exchanger ( 3 ) during normal operation of the cryogenic refrigeration system ( 1 ) provided by an NTU configuration of the heat exchanger ( 3 ).   
     
     
         14 . Method according to  claim 12  or  13 , wherein the supply flow ( 10 ) comprises a pressurized liquid, preferably liquid helium, wherein reducing the pressure of the supply flow ( 10 ) by the pressure regulator ( 4 ) provides a two-phase process medium ( 13 ) flow downstream of the pressure regulator ( 4 ) and wherein the evaporated gas in the vessel is provided at sub-atmospheric pressure, wherein the cooling of the supply flow ( 10 ) preferably provides the process medium between the lambda point and the saturation temperature downstream of the heat exchanger section ( 2 A) of the conduit ( 2 ), and wherein the vessel ( 5 ) preferably collects the liquid phase ( 15 ) of the process medium to refrigerate a thermally coupled load ( 6 ) or a load ( 6 ) disposed in the liquid phase ( 15 ) of the process medium in the vessel ( 5 ), to provide an isothermal load ( 6 ). 
     
     
         15 . Method according to  claim 12 , wherein the cooling of the supply flow ( 10 ) occurs in series or in parallel by means of a plurality of heat exchanger modules ( 3 A,  3 B,  3 C) arranged in series or in parallel, wherein preferably the pressure of the supply flow ( 10 ) is reduced between each serially arranged heat exchanger module ( 3 A,  3 C) by means of a second pressure regulator ( 4 B).