Thermal performing refrigeration cycle

Abstract

An improved refrigeration cycle is provided. The cycle provides for improved thermal performance by incorporating a refrigerant makeup tank that introduces liquid refrigerant with expanded refrigerant upstream of the heat exchanger, thereby providing a savings in either electricity costs or refrigerant.

We claim: 
     
         1 . An apparatus for producing a liquefied gas stream from an inlet gas feed stream, the apparatus comprising:
 a heat exchanger having a cold side and a warm side, the heat exchanger configured to receive the inlet gas feed stream and to produce the liquefied gas stream;   a refrigeration cycle configured to provide refrigeration to the heat exchanger, the refrigeration cycle further comprising a compressor and an expander, wherein the compressor is configured to compress a refrigerant to a compression pressure, wherein the expander is configured to receive the compressed refrigerant and expand the compressed refrigerant to an expanded pressure to produce a cold refrigerant at an outlet of the expander, wherein the outlet of the expander is in fluid communication with the cold side of the heat exchanger; and   a makeup liquid refrigerant tank configured to introduce a makeup liquid refrigerant with the cold refrigerant prior to heat exchange with the inlet gas feed stream.   
     
     
         2 . The apparatus as claimed in  claim 1 , wherein the makeup liquid refrigerant tank is in fluid communication with the refrigeration cycle at a point downstream the outlet of the expander and upstream the cold side of the heat exchanger. 
     
     
         3 . The apparatus as claimed in  claim 1 , wherein the expander is a device selected from the group consisting of an expansion valve, a turbo-expander, and a liquid expander. 
     
     
         4 . The apparatus as claimed in  claim 1 , further comprising a utility nitrogen withdrawal line configured to withdraw a nitrogen stream from the refrigeration cycle at a point downstream the warm side of the heat exchanger and introduce the nitrogen stream to a second user for use as utility nitrogen.