Refrigerant storage in lng production

Abstract

A refrigerant tank ( 40 ) holds a hydrocarbon refrigerant ( 42 ) used by refrigeration equipment ( 14 ) to cool natural gas to about −163° C. to produce LNG (liquefied natural gas) ( 45 ). The refrigerant is stored on a floating structure ( 10 ) in a way that avoids dangers that would arise if the refrigerant were stored on deck with the refrigeration equipment. A refrigerant container ( 40 ) is stored in one of the LNG tanks ( 20 ) that holds LNG at about −163° C.

1 . A liquefied gas storage facility that includes a hull that floats in a sea, a deck on top of said hull, at least one insulated liquefied gas tank lying primarily in said hull and below said deck and containing cold liquefied gas, and refrigeration equipment that includes expansion, compression and heat transfer portions, wherein said refrigeration equipment includes at least one refrigerant container that holds refrigerant used in at least one of said refrigeration equipment portions, wherein:
 said refrigerant container lies below said deck, in a region that is thermally coupled to liquefied gas that lies in said liquefied gas tank, and the refrigerant temperature is maintained at least 40° C. below the average environmental temperature due to the refrigerant being thermally coupled to the cold liquefied gas.   
     
     
         2 . The facility described in  claim 1  wherein:
 said refrigerant container lies completely within said liquefied gas tank.   
     
     
         3 . The facility described in  claim 1  including:
 walls forming a cavity with said refrigerant container lying in said cavity, said cavity walls including a cold wall that separates said cavity from the inside of said liquefied gas tank, and said cavity having a warm wall that separates said cavity from the warmer environment.   
     
     
         4 . The facility described in  claim 3  wherein:
 said hull includes inner and outer hull walls with said inner hull wall forming one of said walls of said cavity.   
     
     
         5 . The facility described in  claim 1 , wherein:
 said cold liquefied gas is LNG (liquefied natural gas) at a temperature within 20° C. of −163° C., said average environmental temperature is within 25° C. of a temperature of +10° C., said refrigerant is a hydrocarbon and said refrigerant tank lies completely within said liquefied gas tank.   
     
     
         6 . The facility described in  claim 1  wherein:
 said cold liquefied gas is LPG (liquefied petroleum gas) at a temperature within 10° C. of −42° C.   
     
     
         7 . The facility described in  claim 1  wherein:
 said refrigerant container has a vent ( 44 ) that opens to said liquefied gas tank.   
     
     
         8 . A liquefied gas storage facility which includes a hull that floats in a sea and that has a deck lying above the sea, at least one liquefied gas tank lying primarily in said hull, a quantity of LNG (liquefied natural gas) lying in said liquefied gas tank, refrigerant equipment on said hull which includes expansion, compression and heat transfer refrigeration portions and at least one refrigerant container and a quantity of refrigerant in said refrigerant container, wherein:
 said refrigerant container lies within said liquefied gas tank.   
     
     
         9 . The facility described in  claim 8  wherein:
 said refrigerant comprises primarily a hydrocarbon and said refrigerant container has a vent that opens to a region of said liquefied gas tank outside said refrigerant container.   
     
     
         10 . The facility described in  claim 8  wherein:
 the temperature of said LNG is within 25° C. of −163° C. and said refrigerant has a temperature close to −163° C. than to the temperature of the environment.