Multi-refrigerant cooling system with provisions for adjustment of refrigerant composition

Abstract

A multi-refrigerant cooling system comprising a cooling circuit ( 100 ) for circulation of a refrigerant mixture. The cooling circuit comprises, i.a., one or more separator(s) ( 102, 103 ) configured to separate and withdraw a respective refrigerant fraction of the refrigerant mixture. Each separator is connected to a respective holding tank ( 201, 202 ). Each holding tank is further connected to the cooling circuit via a supply conduit ( 207 ), the supply conduit being configured to supply one or more refrigerant fraction(s) to the cooling circuit. Method for adjusting the composition of a refrigerant mixture of a multi-refrigerant cooling system. The method allows adjustment of the composition of the refrigerant mixture during operation of the multi-refrigerant cooling system.

1 . A multi-refrigerant cooling system comprising a cooling circuit ( 100 ) for circulation of a refrigerant mixture comprising two or more refrigerants, the cooling circuit comprising a compressor ( 101 ) having an inlet and an outlet; one or more separator(s) ( 102 ,  103 ) configured to separate and withdraw a respective refrigerant fraction of the refrigerant mixture; and a client ( 104 ), the outlet of the compressor ( 101 ) being connected to the client ( 104 ) via the separator(s) ( 102 ,  103 ), wherein each separator ( 102 ,  103 ) is connected to a respective holding tank ( 201 ,  202 ) via a respective withdrawal conduit ( 210 ,  211 ), each holding tank ( 201 ,  202 ) being arranged to receive said respective refrigerant fraction from its respective separator ( 102 ,  103 ), wherein each holding tank ( 201 ,  202 ) further is connected to the cooling circuit ( 100 ) via a supply conduit ( 207 ), the supply conduit ( 207 ) being configured to supply one or more refrigerant fraction(s) to the cooling circuit ( 100 ). 
   
   
       2 . The system according to  claim 1 , comprising a further holding tank ( 203 ) connected via a further withdrawal conduit ( 214 ) to the cooling circuit ( 100 ) at a position between the separator(s) ( 102 ,  103 ) and the client ( 104 ), the further holding tank ( 203 ) being arranged to receive a refrigerant fraction from the cooling circuit ( 100 ), wherein the further holding tank ( 203 ) further is connected to the cooling circuit ( 100 ) via the supply conduit ( 207 ). 
   
   
       3 . The system according to  claim 1 , wherein the supply conduit ( 207 ) is connected to the cooling circuit ( 100 ) at a position between the client ( 104 ) and the inlet of the compressor ( 101 ). 
   
   
       4 . The system according to  claim 1 , wherein each withdrawal conduit ( 210 ,  211 ,  214 ) is further connected to a flare ( 208 ). 
   
   
       5 . The system according to  claim 1 , wherein the client is a carbon dioxide frosting vessel. 
   
   
       6 . Method for adjusting the composition of a refrigerant mixture of a multi-refrigerant cooling system, said method comprising the following steps:
 a) withdrawing from the multi-refrigerant cooling system one or more fraction(s) of the refrigerant mixture, said fractions being of different refrigerant compositions;   b) supplying to the multi-refrigerant cooling system a refrigerant stream;   so that the composition of the refrigerant mixture of the multi-refrigerant cooling system is adjusted to a new composition, said new composition being different from the composition of the refrigerant stream; and   c) maintaining during steps a) and b) the refrigerant mixture of the multi-refrigerant cooling system in an amount allowing operation of the multi-refrigerant cooling system;   thereby allowing adjustment of the composition of the refrigerant mixture during operation of the multi-refrigerant cooling system.   
   
   
       7 . Method according to  claim 6 , wherein one or more, preferably all, of the fraction(s) withdrawn in step a) is/are individually stored. 
   
   
       8 . Method according to  claim 7 , wherein the refrigerant stream supplied in step b) comprises, preferably consists of, one or more of the stored fraction(s). 
   
   
       9 . Method according to  claim 7 , wherein the number of fractions withdrawn in step a) is equal to or less than, preferably equal to, the number of refrigerants in the refrigerant mixture of the multi-refrigerant cooling system. 
   
   
       10 . Method according to  claim 6 , wherein the fraction(s) withdrawn in step a) is/are discarded. 
   
   
       11 . Method according to  claim 10 , wherein the number of fractions withdrawn in step a) is one. 
   
   
       12 . Method according to  claim 7 , wherein the stored fraction(s) is/are each maintained at a pressure between the pressure of the refrigerant mixture at the position of the multi-refrigerant cooling system where in step a) the respective fraction is withdrawn and the pressure of the refrigerant mixture at the position of the multi-refrigerant cooling where step b) is performed. 
   
   
       13 . Method according to  claim 6 , wherein the fraction(s) withdrawn in step a) is/are each withdrawn at a position of the multi-refrigerant cooling system where the refrigerant mixture is present at a higher pressure than at the position of the multi-refrigerant cooling system where step b) is performed. 
   
   
       14 . Method according to  claim 6 , wherein the multi-refrigerant cooling system cools a carbon dioxide frosting vessel.