Cooling method for liquefying a feed gas

Abstract

The present invention pertains to a cooling method for liquefying a feed gas, comprising the steps of providing a cooling cycle with a refrigerant stream; dividing the refrigerant stream into a first partial stream and a second partial stream; expanding the first partial stream in a first expansion device; and transferring cooling energy from the expanded first partial stream to a feed gas stream to be cooled, particularly comprising hydrogen and/or helium. Further the method comprises the steps of guiding the expanded first partial stream to a suction inlet of an ejector; and guiding the second partial stream to a propellant inlet of the ejector such that, upon expanding the second partial stream in the ejector, the expanded first partial stream is compressed and merged with the expanded second partial stream.

1 . Cooling method for liquefying a feed gas, comprising the steps of:
 providing a cooling cycle with a refrigerant stream;   dividing the refrigerant stream into a first partial stream and a second partial stream;   expanding the first partial stream in a first expansion device; and,   transferring cooling energy from the expanded first partial stream to a feed gas stream to be cooled, wherein the method further comprises the steps of:
 guiding the expanded first partial stream to a suction inlet of an ejector; and, 
 guiding the second partial stream to a propellant inlet of the ejector such that, upon expanding the second partial stream in the ejector, the expanded first partial stream is compressed and merged with the expanded second partial stream. 
   
     
     
         2 . Method according to  claim 1 , wherein, by transferring cooling energy from the expanded first partial stream to the feed gas stream to be cooled, particularly by means of a first heat exchanger, the feed gas stream is cooled to a temperature below the critical temperature of hydrogen, particularly below 24 K, so as to provide a liquid product stream comprising hydrogen. 
     
     
         3 . Method according to  claim 1 , wherein an expanded refrigerant stream is provided by merging the compressed first partial stream with the expanded second partial stream in the ejector, and wherein
 the method further comprises the step of guiding the expanded refrigerant stream through a compressor unit, particularly comprising or consisting of at least one piston compressor so as to compress the expanded refrigerant stream, thereby providing the refrigerant stream.   
     
     
         4 . Method according to  claim 1 , further comprising the step of guiding the expanded refrigerant stream and the first partial stream such that heat is transferred, particularly by means of a second heat exchanger, between the expanded refrigerant stream and the first partial stream and particularly the feed gas stream. 
     
     
         5 . Method according to  claim 1 , further comprising the step of partially expanding the second partial stream in a second expansion device particularly a Joule-Thomson-valve and/or an expansion turbine, prior to being guided to the ejector and/or the step of guiding the second partial stream) into the ejector, particularly by bypassing the second expansion device. 
     
     
         6 . Method according to  claim 1 , wherein the refrigerant stream is further separated into at least one third partial stream, particularly at different temperature levels, and the method further comprises the steps of:
 expanding the at least one third partial stream in at least one third expansion device, particularly in at least one expansion turbine; and   guiding the at least one expanded third partial stream and the first partial stream such that heat is transferred, particularly by means of at least one third heat exchanger, between the at least one expanded third partial stream and the first partial stream and particularly the feed gas stream; and,   feeding the at least one expanded third partial stream to the expanded refrigerant stream.   
     
     
         7 . Method according to  claim 1 , wherein the expanded first partial stream is guided into a gas liquid separator arranged downstream of the first expansion device and configured to store the refrigerant in a liquid and gaseous phase, and wherein the expanded first partial stream in a liquid phase is guided from the separator, particularly through the first heat exchanger acting as an evaporator, to the suction inlet of the ejector. 
     
     
         8 . Method according to  claim 1 , wherein the refrigerant stream) is precooled by means of a closed precooling cycle having a further refrigerant stream comprising or consisting of nitrogen, wherein in particular the further refrigerant stream is expanded in a fourth expansion device prior to being supplied to a fourth heat exchanger for transferring cooling energy to the refrigerant stream and particularly to the feed gas stream. 
     
     
         9 . Cooling system for liquefying a feed gas, having a cooling circuit with a refrigerant line for circulating a refrigerant stream, wherein the cooling circuit further comprises:
 an expansion device configured to expand a first partial stream flowing through a first junction line branching off from the refrigerant line; and,   a heat exchanger for transferring cooling energy from the expanded first partial stream to a feed gas stream to be cooled, wherein   
       the cooling circuit further comprises an ejector having a suction inlet connected to the first junction line for receiving the expanded first partial stream and a propellant inlet connected to a second junction line branching off from the refrigerant line for receiving a second partial stream, wherein the ejector is configured to, upon expanding the second partial stream in the ejector, compress the expanded first partial stream and merge it with the expanded second partial stream. 
     
     
         10 . Cooling system according to  claim 9 , wherein the heat exchanger is configured to transfer cooling energy from the expanded first partial stream to the feed gas stream to be cooled such that the feed gas stream is cooled to a temperature below the critical temperature of hydrogen, particularly below 24 K, so as to provide a liquid product stream comprising hydrogen. 
     
     
         11 . Cooling system according to  claim 9 , wherein the cooling system further comprises a compressor unit configured to compress an expanded refrigerant stream output by the ejector and formed by merging the compressed first partial stream with the expanded second partial stream so as to provide the refrigerant stream, and wherein the compressor unit comprises or consists of at least one piston compressor. 
     
     
         12 . Cooling system according to  claim 9 , further comprising a second heat exchanger configured to transfer heat between the expanded refrigerant stream and the first partial stream and particularly the feed gas stream. 
     
     
         13 . Cooling system according to  claim 9 , further comprising a second expansion device, particularly a Joule-Thomson-valve and/or an expansion turbine, arranged upstream of the ejector and configured to partially expand the second partial stream flowing through the second junction line, wherein particularly a bypass line is provided through which at least a part of the second partial stream is guided and which is configured for bypassing the second expansion device and guiding the second partial stream flowing therethrough into the ejector. 
     
     
         14 . Cooling system according to  claim 9 , further comprising:
 at least one third expansion device configured to expand at least one third partial stream flowing through at least one third junction line which branches off from the refrigerant line at different temperature levels,   at least one third heat exchanger for transferring heat between the at least one expanded third partial stream and the first partial stream and particularly the feed gas stream; and,   at least one supply line arranged downstream of the at least one third heat exchanger for feeding the at least one expanded third partial stream to the expanded refrigerant stream.   
     
     
         15 . Cooling system according to  claim 9 , further comprising:
 a gas liquid separator arranged downstream of the first expansion device and configured to receive the expanded first partial stream and to store the refrigerant of the expanded first partial stream in a liquid and gaseous phase,   an ejector supply line for guiding the expanded first partial stream in a liquid phase from the separator, particularly evaporated in the first heat exchanger, to the suction inlet of the ejector, and/or   a closed precooling cycle for precooling the refrigerant stream of the cooling cycle, wherein the closed precooling cycle has a further refrigerant stream, particularly comprising or consisting of nitrogen or liquid natural gas, a fourth expansion device for expanding the further refrigerant stream, and a fourth heat exchanger configured to transfer heat between the expanded further refrigerant stream and the refrigerant stream and particularly the feed gas stream.