Liquefied Natural Gas Production

Abstract

Hydrocarbon processing systems and a method for liquefied natural gas (LNG) production are described herein. The hydrocarbon processing system includes a fluorocarbon refrigeration system configured to cool a natural gas to produce LNG using a mixed fluorocarbon refrigerant and a nitrogen rejection unit (NRU) configured to remove nitrogen from the LNG.

1 . A hydrocarbon processing system for liquefied natural gas (LNG) production, comprising:
 a fluorocarbon refrigeration system configured to cool a natural gas to produce LNG using a mixed fluorocarbon refrigerant;   a nitrogen rejection unit (NRU) configured to remove nitrogen from the LNG; and   an autorefrigeration system configured to further cool the natural gas to produce the LNG.   
     
     
         2 . The hydrocarbon processing system of  claim 1 , comprising a nitrogen refrigeration system configured to further cool the natural gas to produce the LNG using a nitrogen refrigerant. 
     
     
         3 . (canceled) 
     
     
         4 . The hydrocarbon processing system of  claim 1 , wherein the autorefrigeration system comprises a plurality of flash drums and a plurality of expansion devices. 
     
     
         5 . The hydrocarbon processing system of  claim 1 , wherein at least a portion of the natural gas is cooled using a nitrogen stream separated from the natural gas via the NRU. 
     
     
         6 . The hydrocarbon processing system of  claim 1 , wherein the fluorocarbon refrigeration system comprises a single mixed refrigerant cycle. 
     
     
         7 . The hydrocarbon processing system of  claim 1 , wherein the fluorocarbon refrigeration system comprises a pre-cooled mixed refrigerant cycle. 
     
     
         8 . The hydrocarbon processing system of  claim 1 , wherein the fluorocarbon refrigeration system comprises a dual mixed refrigerant cycle. 
     
     
         9 . The hydrocarbon processing system of  claim 8 , wherein the dual mixed refrigerant cycle comprises:
 a first mixed refrigerant cycle that uses a warm mixed fluorocarbon refrigerant; and   a second mixed refrigerant cycle that uses a cold mixed fluorocarbon refrigerant, wherein the first mixed refrigerant cycle and the second mixed refrigerant cycle are connected in series.   
     
     
         10 . The hydrocarbon processing system of  claim 1 , wherein the fluorocarbon refrigeration system comprises a triple mixed refrigerant cycle. 
     
     
         11 . The hydrocarbon processing system of  claim 1 , wherein the fluorocarbon refrigeration system comprises a heat exchanger configured to allow for cooling of the natural gas via an indirect exchange of heat between the natural gas and the mixed fluorocarbon refrigerant. 
     
     
         12 . The hydrocarbon processing system of  claim 1 , wherein the fluorocarbon refrigeration system comprises:
 a compressor configured to compress the mixed fluorocarbon refrigerant to provide a compressed mixed fluorocarbon refrigerant;   a chiller configured to cool the compressed mixed fluorocarbon refrigerant to provide a cooled mixed fluorocarbon refrigerant; and   a heat exchanger configured to cool the natural gas via indirect heat exchange with the cooled mixed fluorocarbon refrigerant.   
     
     
         13 . The hydrocarbon processing system of  claim 1 , wherein the hydrocarbon processing system is configured to chill the natural gas for hydrocarbon dew point control. 
     
     
         14 . The hydrocarbon processing system of  claim 1 , wherein the hydrocarbon processing system is configured to chill the natural gas for natural gas liquid extraction. 
     
     
         15 . The hydrocarbon processing system of  claim 1 , wherein the hydrocarbon processing system is configured to separate methane and lighter gases from carbon dioxide and heavier gases. 
     
     
         16 . The hydrocarbon processing system of  claim 1 , wherein the hydrocarbon processing system is configured to prepare hydrocarbons for liquefied petroleum gas production storage. 
     
     
         17 . The hydrocarbon processing system of  claim 1 , wherein the hydrocarbon processing system is configured to condense a reflux stream. 
     
     
         18 . A method for liquefied natural gas (LNG) production, comprising:
 cooling a natural gas to produce LNG in a fluorocarbon refrigeration system using a mixed fluorocarbon refrigerant; [[and]]   removing nitrogen from the LNG in a nitrogen rejection unit (NRU); and further cooling the natural gas to produce the LNG in an autorefrigeration system.   
     
     
         19 . The method of  claim 18 , comprising further cooling the natural gas to produce the LNG in a nitrogen refrigeration system using a nitrogen refrigerant. 
     
     
         20 . (canceled) 
     
     
         21 . The method of  claim 18 , comprising cooling at least a portion of the natural gas using a nitrogen stream separated from the natural gas via the NRU. 
     
     
         22 . The method of  claim 18 , wherein cooling the natural gas in the fluorocarbon refrigeration system comprises:
 compressing the mixed fluorocarbon refrigerant to provide a compressed mixed fluorocarbon refrigerant;   cooling the compressed mixed fluorocarbon refrigerant by indirect heat exchange with a cooling fluid to provide a cooled mixed fluorocarbon refrigerant;   passing the cooled mixed fluorocarbon refrigerant to a heat exchange area; and   heat exchanging the natural gas with the cooled mixed fluorocarbon refrigerant in the heat exchange area.   
     
     
         23 . A hydrocarbon processing system for formation of a liquefied natural gas (LNG), comprising:
 a mixed refrigerant cycle configured to cool a natural gas using a mixed fluorocarbon refrigerant, wherein the mixed refrigerant cycle comprises a heat exchanger configured to allow for cooling of the natural gas via an indirect exchange of heat between the natural gas and the mixed fluorocarbon refrigerant;   a nitrogen rejection unit (NRU) configured to remove nitrogen from the natural gas; and   a methane autorefrigeration system configured to cool the natural gas to produce the LNG.   
     
     
         24 . The hydrocarbon processing system of  claim 23 , wherein the mixed fluorocarbon refrigerant comprises a mixture of two or more hydrofluorocarbon refrigerants. 
     
     
         25 . The hydrocarbon processing system of  claim 23 , wherein a nitrogen stream separated from the natural gas via the NRU is used to cool at least a portion of the natural gas. 
     
     
         26 . The hydrocarbon processing system of  claim 23 , wherein the methane autorefrigeration system comprises a plurality of expansion devices and a plurality of flash drums.