System and method for producing liquefied natural gas

Abstract

A system, and a method for producing liquefied natural gas are provided. The system includes a heat exchanger, a first supersonic chiller, and a compression unit. The heat exchanger is for cooling a feed natural gas stream to obtain a cooled natural gas stream. The first supersonic chiller is for chilling the cooled natural gas stream to produce liquefied natural gas and output at least a portion of chilled gaseous natural gas to the heat exchanger to be heated to obtain a heated natural gas stream. The compression unit is for compressing the heated natural gas stream from the heat exchanger and providing a compressed natural gas stream to the heat exchanger to be cooled together with the feed natural gas stream by heat exchanging with the at least a portion of the chilled gaseous natural gas.

1 . A system, comprising:
 a heat exchanger for cooling a feed natural gas stream to obtain a cooled natural gas stream;   a first supersonic chiller for chilling the cooled natural gas stream to produce liquefied natural gas and output at least a portion of chilled gaseous natural gas to the heat exchanger to be heated to obtain a heated natural gas stream; and   a compression unit for compressing the heated natural gas stream and providing a compressed natural gas stream to the heat exchanger to he cooled together with the feed natural gas stream by heat exchanging with the at least a portion of the chilled gaseous natural gas.   
     
     
         2 . The system of  claim 1 , wherein the first supersonic chiller comprises a first outlet for outputting a first portion of the chilled gaseous natural gas and a second outlet for outputting a mixture stream comprising the liquefied natural gas and another portion of the chilled gaseous natural gas, and the system comprises at least one separation vessel in communication with the second outlet of the first supersonic chiller for separating at least a portion of the chilled gaseous natural gas from the mixture stream. 
     
     
         3 . The system of  claim 2 , wherein the at least one separation vessel comprises a first separation vessel for separating a second portion of the chilled gaseous natural gas from the mixture stream and outputting the liquefied natural gas, the system comprises a first pressure reducing device in communication with the first separation vessel for reducing a pressure of the liquefied natural gas from the first separation vessel and outputting a gas-liquid mixture including liquefied natural gas and low pressure gaseous natural gas, and the system comprises a second separation vessel for separating the low pressure gaseous natural gas from the gas-liquid mixture from the first pressure reducing device. 
     
     
         4 . The system of  claim 3 , comprising a collection device for receiving the first portion, the second portion of the chilled gaseous natural gas and the low pressure gaseous natural gas, and outputting a recycled stream of the first portion, the second portion and the low pressure gaseous natural gas at same pressure to the heat exchanger. 
     
     
         5 . The system of  claim 1 , comprising a third separation vessel in communication with the heat exchanger for removing a natural gas liquid from the cooled natural gas stream from the heat exchanger. 
     
     
         6 . The system of  claim 1 , comprising a cooling device for cooling the at least a portion of the chilled gaseous natural gas from the first supersonic chiller to the heat exchanger. 
     
     
         7 . The system of  claim 6 , wherein the cooling device comprises a second pressure reducing device. 
     
     
         8 . The system of  claim 6 , wherein the cooling device comprises an expander. 
     
     
         9 . The system of  claim 1 , comprising a second supersonic chiller for removing a natural gas liquid from the feed natural gas stream. 
     
     
         10 . The system of  claim 9 , comprising a dehydration unit positioned downstream of the second supersonic chiller, wherein the second supersonic chiller is for removing at least a portion of water vapor from the feed natural gas stream and the dehydration unit is for removing water vapor from the feed natural gas stream from the second supersonic chiller. 
     
     
         11 . The system of  claim 9 , comprising a dehydration unit positioned upstream of the second supersonic chiller for removing water vapor from the feed natural gas stream. 
     
     
         12 . A method, comprising:
 cooling a feed natural gas stream to obtain a cooled natural gas stream;   producing, via a first supersonic chiller, liquefied natural gas using the cooled natural gas stream and outputting the liquefied natural gas and chilled gaseous natural gas from the first supersonic chiller;   heating at least a portion of the chilled gaseous natural gas;   compressing the heated natural gas stream to obtain a compressed natural gas stream; and   cooling the compressed natural gas stream together with the feed natural gas stream by heat exchanging with the at least a portion of the chilled gaseous natural gas.   
     
     
         13 . The method of  claim 12 , wherein outputting the liquefied natural gas and the chilled gaseous natural gas comprises outputting a first portion of the chilled gaseous natural gas and outputting a mixture stream comprising the liquefied natural gas and another portion of the chilled gaseous natural gas, and the method comprises separating at least a portion of the chilled gaseous natural gas from the mixture stream. 
     
     
         14 . The method of  claim 13 , wherein the separating comprises,
 separating a second portion of the chilled gaseous natural gas from the mixture stream,   reducing a pressure of the liquefied natural gas to obtain a gas-liquid mixture of liquefied natural gas and low pressure gaseous natural gas, and   separating the low pressure gaseous natural gas from the gas-liquid mixture.   
     
     
         15 . The method of  claim 14 , comprising collecting the first portion, the second portion of the chilled gaseous natural gases and the low pressure gaseous natural gas at same pressure. 
     
     
         16 . The method of  claim 12 , comprising removing a natural gas liquid from the cooled natural gas stream. 
     
     
         17 . The method of  claim 12 , comprising cooling the at least a portion of the chilled gaseous natural gas from the first supersonic chiller before the heating. 
     
     
         18 . The method of  claim 12 , comprising removing, via a second supersonic chiller, a natural gas liquid from the feed natural gas stream before cooling the feed natural gas stream. 
     
     
         19 . The method of  claim 18 , comprising removing, via the second supersonic chiller, at least a portion of water vapor from the feed natural gas stream, and removing, via a dehydration unit, water vapor from the feed natural gas stream from the second supersonic chiller. 
     
     
         20 . The method of  claim 18 , comprising removing, via a dehydration unit, water vapor from the feed natural gas stream before removing the natural gas liquid.