Device and method for liquefying a gas

Abstract

The invention relates to a device (200) for liquefying a gas (51), the device comprising:a circuit (55) for conveying gas to be liquefied, the circuit comprising at least one heat exchanger (204) for exchanging heat between the gas (51) to be liquefied and a refrigerant flow (52) comprising at least dihydrogen refrigerant;a closed refrigeration circuit (210) configured to convey the refrigerant flow,the closed refrigeration circuit comprising a means (215) for maintaining an internal composition of the dihydrogen refrigerant at a ratio of parahydrogen to orthohydrogen that is lower or higher than the ratio corresponding to a natural equilibrium composition in the refrigerant flow closed circuit, the means (215) comprising a catalytic reactor (220) configured to convert some of the orthohydrogen from the dihydrogen refrigerant flow into parahydrogen or vice versa.

1 . A device for liquefying a gas, which device comprises:
 a circuit for conveying gas to be liquefied, the circuit comprising at least one heat exchanger for exchanging heat between the gas to be liquefied and a refrigerant flow comprising at least dihydrogen refrigerant;   a closed refrigeration circuit configured to convey the refrigerant flow,   
       the closed refrigeration circuit comprising a means for maintaining an internal composition of the dihydrogen refrigerant at a ratio of parahydrogen to orthohydrogen that is lower or higher than the ratio corresponding to a natural equilibrium composition in the closed refrigerant flow circuit, this maintenance means comprising a catalytic reactor configured to convert some of the orthohydrogen from the dihydrogen refrigerant flow into parahydrogen or vice versa. 
     
     
         2 . The device according to  claim 1 , wherein the closed refrigeration circuit is configured such that the dihydrogen refrigerant has, on input to the catalytic reactor, a temperature essentially equal to the average temperature of the dihydrogen refrigerant in the closed circuit. 
     
     
         3 . The device according to  claim 1 , wherein the catalytic reactor is positioned on a hot branch of the closed refrigeration circuit. 
     
     
         4 . The device according to  claim 1 , wherein the catalytic reactor is configured to operate according to a temperature between 31 K and 184 K. 
     
     
         5 . The device according to  claim 1 , wherein the maintenance means is configured to maintain the proportion of parahydrogen in the internal composition of the dihydrogen refrigerant between 27% and 96%. 
     
     
         6 . The device according to  claim 1 , wherein the maintenance means comprises a bypass of the catalytic reactor configured to operate a predefined throughput ratio between the flow passing through the reactor and the flow passing through the bypass. 
     
     
         7 . The device according to  claim 1 , wherein the closed dihydrogen refrigerant circuit ( 210 ,  310 ,  410 ,  510 ,  610 ,  710 ,  810 ) is configured to maintain an average temperature of the dihydrogen refrigerant between 31 K and 184 K. 
     
     
         8 . The device according to  claim 1 , which comprises a circuit ( 54 ) for pre-cooling the gas to be liquefied, this pre-cooling circuit comprising a heat exchanger ( 203 ,  303 ,  403 ,  503 ,  603 ,  703 ,  802 ) for exchanging heat between a pre-cooling fluid flow and the dihydrogen refrigerant flow ( 52 ). 
     
     
         9 . The device according to  claim 1 , wherein the gas to be liquefied is a flow comprised essentially of dihydrogen. 
     
     
         10 . The device according to  claim 1 , wherein at least one catalytic reactor is integrated into a heat exchanger. 
     
     
         11 . The device according to  claim 1 , wherein the closed refrigeration circuit comprises a stage of intercooling compression and at least one stage of compression at a temperature below −40° C. for the dihydrogen refrigerant. 
     
     
         12 . The device according to  claim 1 , wherein the catalytic reactor ( 820 ) is positioned on a cold branch of the closed refrigeration circuit ( 810 ). 
     
     
         13 . The device according to  claim 1 , wherein the closed refrigeration circuit comprises at least one compressor of the dihydrogen refrigerant at ambient temperature and a storage tank for the liquid dihydrogen refrigerant. 
     
     
         14 . The device according to  claim 1 , wherein the catalytic reactor utilises a catalyser comprising a member of the iron oxides family, preferably Fe 2 O 3 . 
     
     
         15 . A method for liquefying a gas, characterised in that it comprises:
 a step of conveying gas to be liquefied, the step comprising at least one step of exchanging heat between the gas to be liquefied and a refrigerant flow comprising at least dihydrogen refrigerant;   a step of conveying, in a closed refrigeration circuit, the refrigerant flow,   
       the conveying step comprising a step of maintaining an internal composition of the dihydrogen refrigerant at a ratio of parahydrogen to orthohydrogen that is lower or higher than the ratio corresponding to a natural equilibrium composition in the closed refrigerant flow circuit, this maintenance means comprising a catalytic reaction step to convert some of the orthohydrogen from the dihydrogen refrigerant into parahydrogen or vice versa.