A system for producing liquefied natural gas and method

Abstract

The system comprises a natural gas feed and a natural gas liquefaction facility having a refrigeration circuit comprising: a compressor adapted to compress at least one refrigerant fluid; a driver adapted to drive the compressor; and a heat exchanger adapted to receive a flow of natural gas from the natural gas feed and remove heat therefrom by heat exchange against the refrigerant fluid. A heat pump collects low-temperature thermal energy rejected from the natural gas liquefaction facility and transfers the collected thermal energy to a thermal energy storage system at a higher temperature. The system further comprises a processing facility powered by thermal energy from the thermal energy storage system.

1 . A natural gas liquefaction system, comprising: a natural gas feed; a refrigeration circuit including:
 a refrigeration compressor adapted to compress at least one refrigerant fluid;   a refrigerant cooler adapted to remove low-temperature thermal energy from the refrigerant fluid;   a driver adapted to drive the refrigeration compressor;   a heat exchanger adapted to receive a flow of natural gas from the natural gas feed and remove heat therefrom through heat exchange against refrigerant fluid; and,   a heat pump adapted to recover low-temperature thermal energy rejected from the natural gas liquefaction system and to transfer the rejected thermal energy to a thermal energy storage system at a temperature higher than the temperature at which the thermal energy has been rejected.   
     
     
         2 . The system of  claim 1 , wherein the heat pump is adapted to recover thermal energy rejected by the refrigerant cooler. 
     
     
         3 . The system of  claim 1 , further including at least one processing facility, powered by thermal energy from the thermal energy storage system. 
     
     
         4 . The system of  claim 3 , wherein the at least one processing facility; comprises a gas pre-treatment facility, adapted to receive raw natural gas and pretreat said raw natural gas prior to deliver the natural gas to the natural gas liquefaction facility. 
     
     
         5 . The system of  claim 1 , wherein the driver comprises at least one electric motor; and further comprising at least one electric generator, configured to generate electric energy to power the electric motor, and a thermal energy conversion system adapted to convert thermal energy into mechanical energy and to drive the at least one electric generator therewith. 
     
     
         6 . The system of  claim 5 , wherein the thermal energy conversion system comprises an internal combustion engine, preferably a gas turbine engine, fueled with natural gas directly or indirectly delivered by the natural gas feed. 
     
     
         7 . The system of  claim 6 , further comprising a waste heat recovery unit adapted to recover waste heat from the internal combustion engine and transfer waste heat to the thermal energy storage system. 
     
     
         8 . The system of  claim 6 , wherein the at least one processing facility comprises a carbon dioxide capturing facility adapted to receive flue gas from the internal combustion engine and remove carbon dioxide therefrom. 
     
     
         9 . The system of  claim 5 , wherein the thermal energy conversion system comprises a thermodynamic circuit adapted to receive thermal energy from the thermal energy storage system. 
     
     
         10 . The system of  claim 9 , wherein the thermodynamic circuit comprises a steam or vapor turbine drivingly coupled to the at least one electric generator. 
     
     
         11 . The system of  claim 6 , wherein the thermal energy conversion system further comprises a low-temperature thermodynamic circuit configured to receive waste heat from the internal combustion engine; wherein preferably the low-temperature thermodynamic circuit comprises a steam or vapor turbine drivingly coupled to the at least one electric generator. 
     
     
         12 . The system of  claim 5 , wherein the at least one electric generator is electrically connected to at least one of: the heat pump; and the at least one processing facility. 
     
     
         13 . The system of  claim 5 , wherein the at least one electric generator is functionally coupled to an energy storage facility, adapted to store a surplus energy generated by the at least one electric generator. 
     
     
         14 . The system of  claim 1 , further comprising a renewable energy collector adapted to collect energy from a renewable energy source. 
     
     
         15 . The system of  claim 14 , wherein: the renewable energy collector is adapted to convert energy from the renewable energy resource into a storageable energy, preferably into one of: thermal energy and electric energy; and the renewable energy collector is functionally coupled to at least one of said thermal energy storage system and an additional energy storage system. 
     
     
         16 . The system of  claim 1 , further comprising a liquefied natural gas storage and offloading facility; and wherein the liquefied natural gas storage and offloading facility is powered by electric energy generated by the at least one electric generator. 
     
     
         17 . A modular skid, comprising: a refrigeration circuit configured to couple with a natural gas feed, the refrigeration circuit including: a refrigeration compressor adapted to compress at least one refrigerant fluid; a refrigerant cooler adapted to remove low-temperature thermal energy from the refrigerant fluid; a heat exchanger adapted to receive a flow of natural gas from the natural gas feed and remove heat therefrom by heat exchange with the refrigerant fluid; a heat pump adapted to be coupled to a source of low-temperature rejected thermal energy and to couple with a thermal energy storage system, the heat pump adapted to collect rejected low-temperature thermal energy and transfer the rejected thermal energy to the thermal energy storage system at a higher temperature. 
     
     
         18 . The modular skid of  claim 17 , wherein a cold side of the heat pump is configured to recover heat from the refrigerant cooler. 
     
     
         19 . A method for liquefying natural gas with a natural gas liquefaction system, the natural gas liquefaction system including: a heat exchanger; a refrigeration compressor adapted to compress a refrigerant fluid; a refrigerant cooler adapted to remove low-temperature thermal energy from the refrigerant fluid; a driver adapted to drive the refrigeration compressor; the method comprising the following steps: flowing natural gas in the heat exchanger and removing thermal energy from the natural gas by heat exchange against the refrigerant fluid; removing low-temperature thermal energy from the refrigerant fluid through the refrigerant cooler; and recovering low-temperature thermal energy rejected from the natural gas liquefaction system and transferring the rejected thermal energy to a thermal energy storage system at a higher temperature through a heat pump. 
     
     
         20 . The method of  claim 19 , wherein the step of recovering low-temperature thermal energy rejected from the natural gas liquefaction system comprises the step of recovering low-temperature thermal energy removed from the refrigerant fluid through the refrigerant cooler. 
     
     
         21 . The method of  claim 19 , further comprising the step of delivering thermal energy from the thermal energy storage system to at least one processing facility; of the natural gas liquefaction system. 
     
     
         22 . The method of  claim 21 , wherein the at least one processing facility includes a gas pre-treatment facility, and wherein the method further comprises the step of treating a flow of raw natural gas in the gas pre-treatment facility prior to introducing the natural gas in the heat exchanger. 
     
     
         23 . The method of  claim 22 , wherein the step of recovering low-temperature thermal energy rejected from the natural gas liquefaction system comprises the step of recovering thermal energy rejected from the gas pre-treatment facility. 
     
     
         24 . The method of  claim 19 , wherein the driver comprises an electric motor, the method further comprising the following steps: converting thermal energy into mechanical energy in at least one thermodynamic cycle; converting mechanical energy into electric energy with at least one electric generator, and powering said electric motor therewith. 
     
     
         25 . The method of  claim 24 , wherein the step of converting thermal energy into mechanical energy comprises the step of powering an internal combustion engine, preferably a gas turbine engine, with natural gas; and wherein the step of converting mechanical energy into electric energy comprises the step of driving the at least one electric generator with said internal combustion engine. 
     
     
         26 . The method of  claim 25 , further comprising the step of capturing carbon dioxide from flue gas generated by the internal combustion engine in a carbon dioxide capturing facility powered with thermal energy from the thermal energy storage system. 
     
     
         27 . The method of  claim 25 , further comprising the step of collecting waste heat from the internal combustion engine and further converting said waste heat in mechanical energy with a low-temperature thermodynamic cycle. 
     
     
         28 . The method of  claim 25 , further comprising the step of collecting waste heat from the internal combustion engine and transferring said collected waste heat to the thermal energy storage system. 
     
     
         29 . The method of  claim 24 , further comprising the step of powering the heat pump with electric energy generated by the at least one electric generator. 
     
     
         30 . The method of  claim 19 , further comprising the step of collecting energy from a renewable energy source; and further comprising at least one of the following steps: storing said collected energy; or converting said collected energy into electric energy and using the electric energy in the at least one processing facility. 
     
     
         31 . The method of  claim 30 , wherein the step of storing said collected energy comprises the step of converting said collected energy into thermal energy and storing the converted thermal energy in the thermal energy storage system.