Patent ID: 9163873
Filing Date: 2015-10-20
Classification: F25J

Abstract:
1. A method for producing liquefied and sub-cooled natural gas using a refrigeration assembly comprising a single phase gaseous refrigerant and comprising at least two refrigeration cycles each comprising an expander arranged in an expander loop, wherein a single-component refrigerant is used as the refrigerant in all expander loops, a compressor assembly, a heat exchanger structure for heat absorption from natural gas, a heat rejection assembly and an inventory vessel, the method comprising: passing an expanded refrigerant flow from each respective expander into the heat exchanger structure, each expander being at a mass flow and temperature level adapted to perform de-superheating, condensation or cooling of dense phase and/or sub-cooling of natural gas; and serving the refrigerant to each respective expander in a compressed flow using the compressor assembly having compressors or compressor stages enabling adapted inlet and outlet pressures for each respective expander, wherein each of the refrigeration cycles is connected to the inventory vessel, and refrigeration capacities of the refrigeration cycles are controlled independently from each other by varying refrigerant inventories of the refrigeration cycles using the inventory vessel and valves.