Cryogenic Gas Cooling System and Method

Abstract

A pre-cool refrigeration circuit includes a pre-cool compressor configured to receive and compress pre-cool refrigerant vapor from a pre-cool heat exchanger, a pre-cool cooling device configured to receive and cool compressed pre-cool refrigerant from the pre-cool compressor, a pre-cool expansion device configured to receive and expand compressed and cooled pre-cool refrigerant from the pre-cool cooling device, and a pre-cool separation device configured to receive expanded pre-cool refrigerant from the pre-cool expansion device at a reduced pressure so as to lower a boiling point of the expanded pre-cool refrigerant and to separate the expanded pre-cool refrigerant into a pre-cool refrigerant vapor stream and a pre-cool refrigerant liquid stream. A primary refrigeration circuit includes a first primary compressor configured to receive and compress a primary refrigerant vapor from a liquefier heat exchanger and the pre-cool heat exchanger, a primary cooling device configured to receive and cool compressed primary refrigerant from the first primary compressor. The primary cooling device is in fluid communication with the pre-cool heat exchanger and the liquefier heat exchanger. A first primary expansion device is configured to receive and expand compressed and cooled primary refrigerant from the liquefier heat exchanger, with the first primary expansion device having an outlet in fluid communication with the liquefier heat exchanger and the pre-cool heat exchanger.

What is claimed is: 
     
         1 . A system for liquefying a cryogenic gas feed stream comprising:
 a. a pre-cool heat exchanger including a pre-cool refrigerant warming passage, a primary refrigerant cooling passage a primary refrigerant warming passage and a feed gas cooling passage;   b. a pre-cool refrigeration circuit including:
 i) a pre-cool compressor configured to receive and compress pre-cool refrigerant vapor from the pre-cool refrigerant warming passage of the pre-cool heat exchanger; 
 ii) a pre-cool cooling device configured to receive and cool compressed pre-cool refrigerant from the pre-cool compressor; 
 iii) a pre-cool expansion device configured to receive and expand compressed and cooled pre-cool refrigerant from the pre-cool cooling device; 
 iv) a pre-cool separation device configured to receive expanded pre-cool refrigerant from the pre-cool expansion device at a reduced pressure so as to lower a boiling point of the expanded pre-cool refrigerant and to separate the expanded pre-cool refrigerant into a pre-cool refrigerant vapor stream and a pre-cool refrigerant liquid stream, said pre-cool separation device having a vapor outlet and a liquid outlet in fluid communication with the pre-cool refrigerant warming passage of the pre-cool heat exchanger; 
   c. a liquefier heat exchanger including a primary refrigerant cooling passage, primary refrigerant warming passage and a feed gas cooling passage;   d. a primary refrigeration circuit including:
 i) a first primary compressor configured to receive and compress a primary refrigerant vapor from the primary refrigerant warming passages of the liquefier heat exchanger and the pre-cool heat exchanger; 
 ii) a primary cooling device configured to receive and cool compressed primary refrigerant from the first primary compressor, said primary cooling device having an outlet in fluid communication with the primary refrigerant cooling passages of the pre-cool heat exchanger and the liquefier heat exchanger; 
 iii) a first primary expansion device configured to receive and expand compressed and cooled primary refrigerant from the primary refrigerant cooling passage of the liquefier heat exchanger, said first primary expansion device having an outlet in fluid communication with the primary refrigerant warming passages of the liquefier heat exchanger and the pre-cool heat exchanger; 
   e. said pre-cool heat exchanger configured so that primary refrigerant in the primary refrigerant cooling passage of the pre-cool heat exchanger and cryogenic gas in the feed gas cooling passage are cooled by pre-cool refrigerant in the pre-cool refrigerant warming passage and primary refrigerant in the primary refrigerant warming passage; and   f. said liquefier heat exchanger configured so that primary refrigerant in the primary refrigerant cooling passage is cooled and cryogenic fluid in the feed gas cooling passage is liquefied by primary refrigerant in the primary refrigerant warming passage.   
     
     
         2 . The system of  claim 1 , further comprising pre-cool cold box within which the pre-cool heat exchanger is positioned and a liquefier cold box within which the liquefier heat exchanger is positioned. 
     
     
         3 . The system of  claim 2  wherein the liquefier heat exchanger is vacuum insulated. 
     
     
         4 . The system of  claim 1  wherein the first primary expansion device is a Joule-Thompson valve. 
     
     
         5 . The system of  claim 1  wherein the liquefaction heat exchanger includes a first liquefaction heat exchanger having a first primary refrigerant cooling passage, a first primary refrigerant warming passage and a second primary refrigerant warming passage, said liquefaction heat exchanger also including a second liquefaction heat exchanger having a second primary refrigerant cooling passage, a third primary refrigerant cooling passage, a third primary refrigerant warming passage and a fourth primary refrigerant warming passage and further comprising;
 g. a split configured to receive primary refrigerant exiting the first primary refrigerant passage cooling passage; 
 h. a second primary expansion device configured to receive a first portion of primary refrigerant from the split, said second primary expansion device having a second primary expansion device outlet; 
 i. said second primary refrigerant cooling passage of the second heat exchanger configured to receive and cool the first portion of primary refrigerant from the second primary expansion device outlet, said second primary refrigerant cooling passage in fluid communication with the third and first primary refrigerant warming passages; 
 j. said third primary refrigerant cooling passage of the second heat exchanger configured to receive and cool a second portion of primary refrigerant from the split, said third primary refrigerant cooling passage in fluid communication with the fourth and second primary refrigerant warming passages. 
 
     
     
         6 . The system of  claim 5  wherein the second primary expansion device is a turbine. 
     
     
         7 . The system of  claim 5  further comprising a third primary expansion device configured to receive the first portion of primary refrigerant from the second primary refrigerant cooling passage of the second liquefaction heat exchanger, said third primary expansion device having a third primary expansion device outlet wherein said third and first primary refrigeration passages are configured to receive the first portion of primary refrigerant from the third primary expansion device outlet. 
     
     
         8 . The system of  claim 7  wherein the second and third expansion devices are turbines. 
     
     
         9 . The system of  claim 5  wherein the first primary compressor has a first primary compressor inlet configured to receive the second portion of primary refrigerant from the second primary refrigerant warming passage of the first heat exchanger and further comprising a second primary compressor having a primary compressor inlet configured to receive primary refrigerant from the first primary refrigerant warming passage and primary refrigerant from the first primary compressor. 
     
     
         10 . The system of  claim 1  wherein the cryogenic gas feed stream includes hydrogen, the primary refrigerant includes hydrogen and the pre-cool refrigerant includes nitrogen. 
     
     
         11 . The system of  claim 1  wherein the pre-cool refrigerant is nitrogen and the pressure within the pre-cool separation device is reduced to approximately 0.5 bar to lower a boiling temperature of the nitrogen from 78 K to approximately 73 K. 
     
     
         12 . The system of  claim 1  wherein the pressure within the pre-cool separation device is reduced to a level whereby a boiling temperature of the pre-cool refrigerant is below 77 K. 
     
     
         13 . A method for liquefying a cryogenic gas feed stream comprising the steps of:
 a. precooling the cryogenic gas feed stream using a pre-cool refrigerant and a primary refrigerant to form a pre-cooled cryogenic fluid stream;   b. liquefying the pre-cooled cryogenic fluid stream using the primary refrigerant;   c. wherein step a. forms a warmed pre-cool refrigerant and steps a. and b. form a warmed primary refrigerant;   d. compressing the warmed pre-cool refrigerant to form a compressed pre-cool refrigerant;   e. cooling the compressed pre-cool refrigerant to form a cooled pre-cool refrigerant;   f. expanding the cooled pre-cool refrigerant to form an expanded pre-cool refrigerant;   g. reducing the pressure of the expanded pre-cool refrigerant so as to lower a boiling point of the pre-cool refrigerant;   h. separating the pre-cool refrigerant of step g. into a pre-cool refrigerant vapor stream and a pre-cool refrigerant liquid stream;   i. vaporizing the pre-cool refrigerant liquid stream during the pre-cooling of step a.;   j. warming the pre-cool refrigerant vapor stream during the pre-cooling of step a.;   k. compressing the warmed primary refrigerant to form a compressed primary refrigerant;   l. cooling the compressed primary refrigerant to form a cooled primary refrigerant;   m. expanding the cooled primary refrigerant to form an expanded primary refrigerant which is warmed during the pre-cooling of step a. and the liquefying of step b.   
     
     
         14 . The method of  claim 13  wherein the cryogenic gas feed stream includes hydrogen, pre-cool refrigerant includes nitrogen and the primary refrigerant includes hydrogen. 
     
     
         15 . The method of  claim 13  wherein the cooling of steps e. and h. are performed using water. 
     
     
         16 . The method of  claim 13  wherein the cooling of step h. includes cooling by the pre-cool refrigerant. 
     
     
         17 . The method of  claim 13  wherein the pre-cool refrigerant is nitrogen and the pressure within the pre-cool separation device is reduced in step g. to approximately 0.5 bar to lower a boiling temperature of the nitrogen from 78 K to approximately 73 K. 
     
     
         18 . The method of  claim 13  wherein the pressure within the pre-cool separation device is reduced in step g. to a level whereby a boiling temperature of the pre-cool refrigerant is below 77 K. 
     
     
         19 . A system for cooling a cryogenic gas feed stream comprising:
 a. a pre-cool heat exchanger including a pre-cool refrigerant warming passage, a primary refrigerant cooling passage a primary refrigerant warming passage and a feed gas cooling passage;   b. a pre-cool refrigeration circuit including:
 i) a pre-cool compressor configured to receive and compress pre-cool refrigerant vapor from the pre-cool refrigerant warming passage of the pre-cool heat exchanger; 
 ii) a pre-cool cooling device configured to receive and cool compressed pre-cool refrigerant from the pre-cool compressor; 
 iii) a pre-cool expansion device configured to receive and expand compressed and cooled pre-cool refrigerant from the pre-cool cooling device; 
 iv) a pre-cool separation device configured to receive expanded pre-cool refrigerant from the pre-cool expansion device at a reduced pressure so as to lower a boiling point of the expanded pre-cool refrigerant and to separate the expanded pre-cool refrigerant into a pre-cool refrigerant vapor stream and a pre-cool refrigerant liquid stream, said pre-cool separation device having a vapor outlet and a liquid outlet in fluid communication with the pre-cool refrigerant warming passage of the pre-cool heat exchanger; 
   c. a cooling heat exchanger including a primary refrigerant cooling passage, primary refrigerant warming passage and a feed gas cooling passage;   d. a primary refrigeration circuit including:
 i) a first primary compressor configured to receive and compress a primary refrigerant vapor from the primary refrigerant warming passages of the cooling heat exchanger and the pre-cool heat exchanger; 
 ii) a primary cooling device configured to receive and cool compressed primary refrigerant from the first primary compressor, said primary cooling device having an outlet in fluid communication with the primary refrigerant cooling passages of the pre-cool heat exchanger and the cooling heat exchanger; 
 iii) a first primary expansion device configured to receive and expand compressed and cooled primary refrigerant from the primary refrigerant cooling passage of the cooling heat exchanger, said first primary expansion device having an outlet in fluid communication with the primary refrigerant warming passages of the cooling heat exchanger and the pre-cool heat exchanger; 
   e. said pre-cool heat exchanger configured so that primary refrigerant in the primary refrigerant cooling passage of the pre-cool heat exchanger and cryogenic gas in the feed gas cooling passage are cooled by pre-cool refrigerant in the pre-cool refrigerant warming passage and primary refrigerant in the primary refrigerant warming passage; and   f. said cooling heat exchanger configured so that primary refrigerant in the primary refrigerant cooling passage is cooled and cryogenic fluid in the feed gas cooling passage is cooled by primary refrigerant in the primary refrigerant warming passage.   
     
     
         20 . A method for cooling a cryogenic gas feed stream comprising the steps of:
 a. precooling the cryogenic gas feed stream using a pre-cool refrigerant and a primary refrigerant to form a pre-cooled cryogenic fluid stream;   b. cooling the pre-cooled cryogenic fluid stream using the primary refrigerant;   c. wherein step a. forms a warmed pre-cool refrigerant and steps a. and b. form a warmed primary refrigerant;   d. compressing the warmed pre-cool refrigerant to form a compressed pre-cool refrigerant;   e. cooling the compressed pre-cool refrigerant to form a cooled pre-cool refrigerant;   f. expanding the cooled pre-cool refrigerant to form an expanded pre-cool refrigerant;   g. reducing the pressure of the expanded pre-cool refrigerant so as to lower a boiling point of the pre-cool refrigerant;   h. separating the pre-cool refrigerant of step g. into a pre-cool refrigerant vapor stream and a pre-cool refrigerant liquid stream;   i. vaporizing the pre-cool refrigerant liquid stream during the pre-cooling of step a.;   j. warming the pre-cool refrigerant vapor stream during the pre-cooling of step a.;   k. compressing the warmed primary refrigerant to form a compressed primary refrigerant;   l. cooling the compressed primary refrigerant to form a cooled primary refrigerant;   m. expanding the cooled primary refrigerant to form an expanded primary refrigerant which is warmed during the pre-cooling of step a. and the cooling of step b.