Refrigerating system with parallel staged economizer circuits and a single or two stage main compressor

Abstract

A refrigeration system ( 20 A) comprises an evaporator ( 27 ), a plurality of compressors ( 32, 34, 35 ) for compressing a refrigerant, a heat rejecting heat exchanger ( 24 ) for cooling the refrigerant, and a plurality of economizer heat exchangers ( 28 A, 28 B). Each of the economizer heat exchangers ( 28 A, 28 B) is configured to inject a portion of the refrigerant into a suction port ( 52, 56 ) of one of the compressors ( 34, 35 ).

1 . A refrigeration system comprising:
 an evaporator;   a plurality of compressors for compressing a refrigerant, each of the compressors having a suction port and a discharge port;   a heat rejecting heat exchanger for cooling the refrigerant; and   a plurality of economizer heat exchangers, wherein each of the economizer heat exchangers is configured to inject a portion of the refrigerant into the suction port of one of the compressors.   
     
     
         2 . The refrigeration system of  claim 1 , wherein one of the compressors is a two-stage compressor having a first compressor cylinder and a second compressor cylinder. 
     
     
         3 . The refrigeration system of  claim 2 , wherein an intercooler is disposed between the first and second compressor cylinders of the two-stage compressor to cool the refrigerant prior to a second stage of compression. 
     
     
         4 . The refrigeration system of  claim 1 , wherein each of the compressors is a single-stage compressor. 
     
     
         5 . The refrigeration system of  claim 1 , wherein the discharge port of each of the compressors is connected to the heat rejecting heat exchanger. 
     
     
         6 . The refrigeration system of  claim 1 , wherein the heat rejecting heat exchanger is a condenser. 
     
     
         7 . The refrigeration system of  claim 1 , wherein the heat rejecting heat exchanger is a gas cooler. 
     
     
         8 . The refrigeration system of  claim 1 , wherein the refrigerant is carbon dioxide. 
     
     
         9 . The refrigeration system of  claim 1 , wherein the plurality of compressors is part of a single, multi-cylinder compressor unit. 
     
     
         10 . The refrigeration system of  claim 1 , wherein the economizer heat exchangers are flash tanks. 
     
     
         11 . A refrigeration system comprising:
 an evaporator;   a two-stage compressor for compressing a refrigerant, the two-stage compressor having a first compressor cylinder and a second compressor cylinder;   a first single-stage compressor for compressing the refrigerant, the first single-stage compressor having a suction port and a discharge port;   a second single-stage compressor for compressing the refrigerant, the second single-stage compressor having a suction port and a discharge port;   a heat rejecting heat exchanger for cooling the refrigerant;   a first economizer circuit configured to inject a first portion of the refrigerant into the suction port of the first single-stage compressor; and   a second economizer circuit configured to inject a second portion of the refrigerant into the suction port of the second single-stage compressor.   
     
     
         12 . The refrigeration system of  claim 11 , wherein the refrigerant is carbon dioxide. 
     
     
         13 . The refrigeration system of  claim 11 , wherein the two-stage compressor, the first single-stage compressor, and the second single-stage compressor are part of a single, multi-cylinder compressor unit. 
     
     
         14 . The refrigeration system of  claim 11 , wherein an intercooler is disposed between the first compressor cylinder and the second compressor cylinder to cool the refrigerant between a first stage of compression and a second stage of compression. 
     
     
         15 . The refrigeration system of  claim 14 , and further comprising:
 a third single-stage compressor having a suction port and a discharge port; and   a third economizer circuit configured to inject a third portion of the refrigerant into the suction port of the third single-stage compressor.   
     
     
         16 . The refrigeration system of  claim 15 , and further comprising:
 a fourth single-stage compressor having a suction port and a discharge port; and   a fourth economizer circuit configured to inject a fourth portion of the refrigerant into the suction port of the fourth single-stage compressor.   
     
     
         17 . The refrigeration system of  claim 16 , and further comprising:
 a fifth single-stage compressor having a suction port and a discharge port; and   a fifth economizer circuit configured to inject a fifth portion of the refrigerant into the suction port of the fifth single-stage compressor.   
     
     
         18 . A method of operating a refrigeration system, the method comprising:
 evaporating a refrigerant;   compressing the refrigerant from a lower pressure to a higher pressure in a plurality of compressors, the plurality of compressors including a two-stage compressor and at least two single-stage compressors, wherein the two-stage compressor includes an intercooler configured to cool the refrigerant between a first stage of compression and a second stage of compression;   cooling the refrigerant in a heat rejecting heat exchanger;   directing the refrigerant through a plurality of economizer heat exchangers each having a main path and an economized path;   injecting a first portion of the refrigerant from the economized path of one of the economizer heat exchangers into a suction port of one of the single-stage compressors; and   injecting a second portion of the refrigerant from the economized path of another one of the economizer heat exchangers into a suction port of another one of the single-stage compressors.   
     
     
         19 . The method of  claim 18 , wherein the refrigerant is carbon dioxide. 
     
     
         20 . The method of  claim 18 , wherein the compressors are part of a single, multi-cylinder compressor unit.