Refrigerant circuit

Abstract

The present invention relates to a refrigerant circuit ( 1 ), in particular for use in a liquefaction plant, the refrigerant circuit ( 1 ) at least comprising: a refrigerator ( 2 ) having an inlet ( 21 ) for refrigerant ( 10 ) and at least one outlet ( 22 ) for refrigerant ( 20 ) evaporated in the refrigerator ( 2 ); a compressor ( 3 ) having an inlet ( 31 ) for receiving the evaporated refrigerant ( 20 ) from the refrigerator ( 2 ) and an outlet ( 34 ) for compressed refrigerant ( 11 a ); a cooler ( 5 ) having an inlet ( 81 ) for compressed refrigerant ( 110 a ) and an outlet ( 82 ) for cooled compressed refrigerant ( 120 a ); a stream splitter ( 6 ) suitable for splitting the cooled compressed refrigerant ( 120 a ) in at least two streams ( 10 a , 130 a ); a first valve ( 7 ), a second valve ( 8 ) and a first relief valve ( 9 ).

1 . Refrigerant circuit ( 1 ), in particular for use in a liquefaction plant, the refrigerant circuit ( 1 ) at least comprising: 
 a refrigerator ( 2 ) having an inlet ( 21 ) for refrigerant ( 10 ) at a refrigeration pressure, and at least one outlet ( 22 ) for refrigerant ( 20 ) evaporated in the refrigerator ( 2 );    a first compressor ( 3 ) having an inlet ( 31 ) for receiving the evaporated refrigerant ( 20 ) from the refrigerator ( 2 ) and an outlet ( 34 ) for compressed refrigerant ( 11   a );    a first cooler ( 5 ) having an inlet ( 81 ) for compressed refrigerant ( 110   a ) and an outlet ( 82 ) for cooled compressed refrigerant ( 120   a );    a first stream splitter ( 6 ) suitable for splitting the cooled compressed refrigerant ( 120   a ) in at least two streams ( 10   a ,  130   a ), the first stream splitter ( 6 ) having an inlet ( 71 ) for receiving the cooled compressed refrigerant ( 120   a ), a first outlet ( 72 ) connected to the inlet ( 21 ) of the refrigerator ( 2 ) and a second outlet ( 73 ) intended for returning refrigerant ( 130   a ) to upstream of the inlet ( 31 ) of the first compressor ( 3 ) at a first connection point ( 11 );    a first valve ( 7 ) between the first outlet ( 72 ) of the first stream splitter ( 6 ) and the inlet ( 21 ) of the refrigerator ( 2 );    a second valve ( 8 ) between the second outlet ( 73 ) of the first stream splitter ( 6 ) and the first connection point ( 11 ); and    a first relief valve ( 9 ) downstream of the outlet ( 34 ) of the first compressor ( 3 ) and upstream of both the first and second valves ( 7 , 8 ).    
   
   
       2 . Refrigerant circuit ( 1 ) according to  claim 1 , wherein the first relief valve ( 9 ) is located between the outlet ( 34 ) of the first compressor ( 3 ) and the inlet ( 81 ) of the first cooler ( 5 ).  
   
   
       3 . Refrigerant circuit ( 1 ) according to  claim 1  or  2 , wherein the refrigerator ( 2 ) has at least two outlets ( 22 ,  24 , . . . ) for refrigerant ( 20 ,  40 , . . . ) evaporated in the refrigerator ( 2 ), the at least two outlets ( 22 ,  24 , . . . ) being connected to the first compressor ( 3 ).  
   
   
       4 . Refrigerant circuit ( 1 ) according to one or more of the preceding claims, wherein the refrigerant circuit ( 1 ) further comprises: 
 a second compressor ( 4 ) having an inlet ( 41 ) for receiving evaporated refrigerant ( 30 ) from the refrigerator ( 2 ) and an outlet ( 44 ) for compressed refrigerant ( 110   b );    a second cooler ( 12 ) having an inlet ( 83 ) for compressed refrigerant ( 110   b ) and an outlet ( 84 ) for cooled compressed refrigerant ( 120   b );    a second stream splitter ( 13 ) suitable for splitting the cooled compressed refrigerant ( 120   b ) in at least two streams ( 10   b ,  130   b ), the second stream splitter ( 13 ) having an inlet ( 74 ) for receiving the cooled compressed refrigerant ( 120   b ), a first outlet ( 75 ) connected to the inlet ( 21 ) of the refrigerator ( 2 ) and a second outlet ( 76 ) intended for returning refrigerant ( 130   b ) to upstream of the inlet ( 41 ) of the second compressor ( 4 ) at a second connection point ( 14 );    a third valve ( 15 ) between the first outlet ( 74 ) of the second stream splitter ( 13 ) and the inlet ( 21 ) of the refrigerator ( 2 );    a fourth valve ( 16 ) between the second outlet ( 73 ) of the second stream splitter ( 13 ) and the connection point ( 11 ); and    a second relief valve ( 17 ) downstream of the outlet ( 44 ) of the second compressor ( 4 ) and upstream of both the third and fourth valves ( 15 , 16 ).    
   
   
       5 . Refrigerant circuit ( 1 ) according to  claim 4 , wherein the second relief valve ( 16 ) is located between the outlet ( 44 ) of the second compressor ( 4 ) and the inlet ( 83 ) of the second cooler ( 12 ).  
   
   
       6 . Refrigerant circuit ( 1 ) according to  claim 4  or  5 , wherein the refrigerator ( 2 ) has at least two outlets ( 23 ,  25 , . . . ) for refrigerant ( 30 ,  50 , . . . ) evaporated in the refrigerator ( 2 ), the at least two outlets ( 23 ,  25 , . . . ) being connected to the second compressor ( 4 ).  
   
   
       7 . Plant for the production of liquefied natural gas, comprising the refrigerant circuit ( 1 ) according to one or more of the preceding claims for cooling a natural gas stream to be liquefied.  
   
   
       8 . Plant according to  claim 7 , further comprising a pre-cooling heat exchanger having an inlet for natural gas and an outlet for cooled natural gas, a distributor having an inlet connected to the outlet for cooled natural gas and having at least two outlets, and at least two main heat exchangers each comprising a first hot side having one inlet connected to one outlet of the distributor and an outlet for liquefied natural gas, which plant further comprises a pre-cooling refrigerant circuit for removing heat from the natural gas in the pre-cooling heat exchanger, and at least two main refrigerant circuits for removing heat from natural gas flowing through the first hot side of the corresponding main heat exchanger, 
 wherein the pre-cooling refrigerant circuit is a refrigerant circuit  1  according to one or more of the preceding claims  1 - 6 .    
   
   
       9 . Method for the production of liquefied natural gas, wherein the natural gas stream to be liquefied is cooled using the refrigerant circuit ( 1 ) according to one or more of the preceding claims  1 - 8 .  
   
   
       10 . Method according to  claim 9 , at least comprising the steps of: 
 evaporating a refrigerant in a refrigerator ( 2 ) thereby cooling a stream to be cooled and obtaining an evaporated refrigerant ( 20 );    compressing the evaporated refrigerant ( 20 ) in a compressor ( 3 ) thereby obtaining a compressed refrigerant ( 110   a );    cooling the compressed refrigerant ( 11   a ) thereby obtaining a cooled compressed refrigerant ( 120   a );    splitting the cooled compressed refrigerant ( 120   a ) in at least two streams ( 10   a ,  130   a );    forwarding a first stream ( 10   a ) to the refrigerator ( 2 ) and a second stream ( 130   a ) to a connection point ( 11 ) downstream of the refrigerator ( 2 ) and upstream of the compressor ( 3 );    removing refrigerant from the refrigerant circuit ( 1 ) by means of a relief valve ( 9 ), if the pressure of the refrigerant at the relief valve ( 9 ) exceeds a pre-selected value.