System and method for natural gas liquefaction

Abstract

A system for natural gas liquefaction includes a natural gas source for providing a flow of natural gas and a moisture removal system located downstream of the natural gas source. The system includes a first heat exchanger located downstream of the moisture removal system for exchanging heat between the natural gas flow path and a first refrigerant flow path of a refrigerant cycle subsystem. The system includes one first throttle valve located downstream of heat exchanger for expanding the flow of natural gas and causing reduction in pressure and temperature of the flow of natural gas. The system includes a filter subassembly for separating solid particles present in the flow of natural gas. The system includes a second heat exchanger located downstream of the filter subassembly and is configured to transfer heat from a natural gas vapor flow path to a second refrigerant flow path of the refrigeration cycle subsystem.

1 . A system for natural gas liquefaction, the system comprising:
 a natural gas source for providing a flow of natural gas;   a moisture removal subsystem located downstream of the natural gas source and configured to remove moisture from a natural gas flow path that is in fluid communication with the natural gas source;   a first heat exchanger located downstream of the moisture removal system and configured for exchanging heat between the natural gas flow path and a first refrigerant flow path of a refrigerant cycle subsystem;   at least one first throttle valve coupled downstream of the first heat exchanger for expanding the flow of natural gas and causing reduction in pressure and temperature of the flow of natural gas and formation of liquid natural gas, solid carbon dioxide particles and cold vapor;   a filter subassembly for separating solid carbon dioxide particles present in the flow of liquid natural gas;   a second heat exchanger located downstream of the filter subassembly and is configured to transfer heat from a natural gas vapor flow path to a second refrigerant flow path of the refrigeration cycle subsystem; and   a storage tank assembly located downstream of the filter assembly for storing liquefied natural gas.   
     
     
         2 . The system of  claim 1 , wherein the refrigerant cycle subsystem comprises a compressor located downstream of the first refrigerant flow path and is configured to compress the refrigerant fluid mixture flowing through the first refrigerant flow path. 
     
     
         3 . The system of  claim 2 , wherein the refrigerant cycle subsystem comprises an air cooler located downstream of the compressor for cooling the refrigerant mixture passing through the compressor. 
     
     
         4 . The system of  claim 1 , wherein the refrigerant cycle subsystem comprises a phase separator located downstream of the air cooler for separating a vapor portion from a liquid portion of the refrigerant mixture. 
     
     
         5 . The system of  claim 4 , wherein the refrigeration cycle subsystem comprises the second refrigerant flow path and a third refrigerant flow path connected to a top end of the phase separator and a bottom end of the phase separator respectively. 
     
     
         6 . The system of  claim 5 , wherein the refrigeration cycle subsystem comprises an ejector located downstream of the third regrigerant flow path for reducing pressure of the refrigerant mixture flowing in the second refrigerant flow path. 
     
     
         7 . The system of  claim 5 , wherein the refrigeration cycle subsystem comprises a three-way valve located downstream of the phase separator in the second refrigerant flow path that connects with the third and the second refrigerant flow paths and controls flow of refrigerant mixture in the second and the third refrigerant flow paths. 
     
     
         8 . The system of  claim 5 , wherein the refrigeration cycle subsystem comprises one second throttle valve located downstream of the first heat exchanger for expanding the refrigerant mixture flowing in the third refrigerant flow path. 
     
     
         9 . The system of  claim 5 , wherein the third refrigerant flow path downstream of the second throttle valve connects with a return flow path of the refrigeration cycle subsystem to form the first refrigeration flow path passing through the first heat exchanger. 
     
     
         10 . The system of  claim 9 , wherein the return flow path carries the refrigerant mixture of the second refrigerant flow path after passing through a plurality of heat exchangers. 
     
     
         11 . The system of  claim 10 , wherein the refrigeration cycle subsystem comprises a third heat exchanger located downstream of the second refrigerant flow path and is configured to transfer heat from the second refrigerant flow path to the return flow path of the refrigeration cycle subsystem. 
     
     
         12 . The system of  claim 10 , wherein the refrigeration cycle subsystem comprises one third throttle valve located downstream of the third heat exchanger for expanding the refrigerant mixture flowing in the second refrigerant flow path. 
     
     
         13 . The system of  claim 1 , wherein the storage tank assembly comprises a heat exchanger integrated with a storage tank. 
     
     
         14 . A method of liquifying a natural gas, the method comprising:
 directing a flow of natural gas from a natural gas source to a moisture removal system for removing moisture;   directing the flow of natural gas through a first heat exchanger for exchanging heat between the natural gas flow path and a first refrigerant flow path of a refrigerant cycle subsystem;   expanding the flow of natural gas passing out of the first heat exchanger via a first throttle valve causing reduction in pressure and temperature of the flow of natural gas and further resulting in liquefaction of the flow of natural gas and formation of liquid natural gas and a flow of cold vapor;   filtering the flow of liquid natural gas for separating solid carbon dioxide particles in a filter subassembly;   directing the flow of cold vapor through a second heat exchanger configured transfer heat from transfer heat from to a second refrigerant flow path of the refrigeration cycle subsystem; and   storing the filtered flow of natural gas natural in a storage tank assembly.   
     
     
         15 . The method of  claim 14 , wherein the filtering of the flow of natural gas comprises channeling a slurry including liquefied natural gas and solidified carbon dioxide towards a filter house; collecting the solidified carbon dioxide on a filter element in the filter house to form a flow of purified liquefied natural gas; and directing a pulse of cleaning fluid through the filter element to remove the solidified carbon dioxide therefrom, wherein the cleaning fluid includes at least one of methane and carbon dioxide. 
     
     
         16 . The method of  claim 15 , further comprising recycling a refrigerant fluid mixture in the refrigeration cycle subsystem through the first refrigeration flow path, a second refrigeration flow path and a third refrigeration flow path. 
     
     
         17 . The method of  claim 16 , further comprising flowing the refrigeration mixture through a third heat exchanger and a second heat exchanger located downstream of the second refrigeration flow path. 
     
     
         18 . The method of  claim 17 , further comprising expanding at least one of the refrigeration mixture flowing in the second refrigeration flow path via a second throttle valve or the third refrigeration flow path via a third throttle valve, wherein the third throttle valve is located downstream of the second heat exchanger and prior to the third heat exchanger. 
     
     
         19 . The method of  claim 15 , further comprising expanding the refrigeration mixture flowing in second refrigeration flow path via a third throttle valve located downstream of the third heat exchanger and prior to the second heat exchanger.