System and method to produce liquefied natural gas using two distinct refrigeration cycles with an integral gear machine

A natural gas liquefaction system configured for producing a stream of liquefied natural gas, comprising:

• at least one heat exchanger having one or more cooling passages and a plurality of warming passages wherein the at least one heat exchanger is configured to liquefy a natural gas containing feed stream traversing the one or more cooling passages via indirect heat exchange with a primary refrigerant stream traversing the one or more of the plurality of warming passages to produce the stream of liquefied natural gas;
• a refrigeration circuit comprising at least two distinct refrigeration cycles with at least two compositionally different working fluids operating at different temperature levels;
• wherein the refrigeration circuit further comprises a plurality of primary refrigerant compression stages and one or more turbines disposed in operative association with the at least one heat exchanger and configured for recirculating a primary refrigerant stream therethrough to provide refrigeration as a first refrigeration cycle of the at least two distinct refrigeration cycles;
• wherein the refrigeration circuit further comprises at least one natural gas compression stage and one or more natural gas turbines disposed in operative association with the at least one heat exchanger and configured for recirculating a secondary refrigerant stream therethrough to provide refrigeration as a second refrigeration cycle of the at least two distinct refrigeration cycles;
• an integral gear compressor machine having at least three pinions and configured for driving the plurality of refrigerant compression stages and at least one natural gas compression stage and receiving work produced by at least one of the one or more primary refrigerant turbines and the one or more natural gas turbines;
• wherein the at least one natural gas compression stage is operatively coupled to the integral gear compressor machine by a first pinion of the at least three pinions and the at least one natural gas compression stage is configured to receive a portion of the natural gas containing feed stream and produce a further compressed natural gas stream that is directed to one or more of the plurality of cooling passages in the at least one heat exchanger;
• and
• wherein the plurality of refrigerant compression stages are operatively coupled to the integral gear compressor machine by a second pinion or a third pinion of the at least three pinions or both the second pinion and the third pinion;
• and
• wherein the one or more natural gas turbines further comprise a warm natural gas turbine configured to expand a portion of the further compressed natural gas stream;
• and
• wherein the one or more primary refrigerant turbines further comprise a cold turbine configured to expand a cold portion of the primary refrigerant stream.