A method for liquefying a natural gas primarily including methane, preferably at least 85% of methane, the other components essentially including nitrogen and C2-C4 alkanes, in which the natural gas to be liquefied is liquefied by circulating at a pressure P0 no lower than the atmospheric pressure (Patm), P0 preferably being higher than the atmospheric pressure, in at least one cryogenic heat-exchanger (EC1, EC2, EC3) by a counter-current closed-circuit circulation in indirect contact with at least one stream of coolant gas remaining in the compressed gaseous state at a pressure P1 that is entering the cryogenic heat-exchanger at a temperature T3′ that is lower than T3, T3 being the liquefaction temperature of the liquefied natural gas at the pressure P0 at the output of said cryogenic exchanger, characterized in that the coolant gas includes a mixture of nitrogen and at least one other component selected from among neon and hydrogen.

A drive system for liquefied natural gas (LNG) refrigeration compressors in a LNG liquefaction plant. Each of three refrigeration compression strings include refrigeration compressors and a multi-shaft gas turbine capable of non-synchronous operation. The multi-shaft gas turbine is operationally connected to the refrigeration compressors and is configured to drive the one or more refrigeration compressors. The multi-shaft gas turbine uses its inherent speed turndown range to start the one or more refrigeration compressors from rest, bring the one or more refrigeration compressors up to an operating rotational speed, and adjust compressor operating points to maximize efficiency of the one or more refrigeration compressors, without assistance from electrical motors with drive-through capability and variable frequency drives.

A drive system for liquefied natural gas (LNG) refrigeration compressors in a LNG liquefaction plant. Each of three refrigeration compression strings include refrigeration compressors and a multi-shaft gas turbine capable of non-synchronous operation. The multi-shaft gas turbine is operationally connected to the refrigeration compressors and is configured to drive the one or more refrigeration compressors. The multi-shaft gas turbine uses its inherent speed turndown range to start the one or more refrigeration compressors from rest, bring the one or more refrigeration compressors up to an operating rotational speed, and adjust compressor operating points to maximize efficiency of the one or more refrigeration compressors, without assistance from electrical motors with drive-through capability and variable frequency drives.

A drive system for liquefied natural gas (LNG) refrigeration compressors in a LNG liquefaction plant. Each of three refrigeration compression strings include refrigeration compressors and a multi-shaft gas turbine capable of non-synchronous operation. The multi-shaft gas turbine is operationally connected to the refrigeration compressors and is configured to drive the one or more refrigeration compressors. The multi-shaft gas turbine uses its inherent speed turndown range to start the one or more refrigeration compressors from rest, bring the one or more refrigeration compressors up to an operating rotational speed, and adjust compressor operating points to maximize efficiency of the one or more refrigeration compressors, without assistance from electrical motors with drive-through capability and variable frequency drives.

A control device for a rotary machine, which is driven by a turbine output torque which is an output of a turbine and an electric motor output torque which is an output of an induction motor, includes: a required output setting unit configured to set a required torque for driving the rotary machine; and a drive source command unit configured to set the electric motor output torque to a minimum torque or higher of the induction motor and to set the turbine output torque to a value obtained by subtracting the electric motor output torque from the required torque when the turbine output torque is greater than or equal to a lower limit in a stable output range of the turbine.

An LNG refrigerant compressor train (1) is disclosed. The train comprises: a driver section (11), drivingly coupled to a compressor section (13) through a shaft line (1). The compressor section is comprised of at least one refrigerant fluid compressor, driven into rotation by the driver section (11).

The system comprises: a main driver configured for rotating at a substantially constant rotational speed; a rotating load configured to be driven into rotation by the main driver; a controller, for controllably adjusting a load rotational speed; a variable speed transmission, arranged between the main driver and the load and comprised of a speed summing gear arrangement having a first input shaft, a second input shaft and an output shaft; an auxiliary driver, mechanically coupled to the second input shaft of the speed summing gear arrangement. The first input shaft of the speed summing gear arrangement is drivingly coupled to the main driver. The output shaft of the speed summing gear arrangement is drivingly coupled to the rotating load. The speed of the output shaft is a combination of a speed of the main driver and of a speed of the auxiliary driver.

A split mixed refrigerant (MR) natural gas liquefication system, where low-pressure (LP) and medium pressure (MP) MR compressors are driven by a first gas turbine and a propane compressor and a high-pressure (HP) MR compressor is driven by a second gas turbine, is disclosed. The split MR liquefication system is configured to adjust the characteristics of the HP MR compressor to require less power when less power is available and more power when more power is available compared to the system's design point. Such adjustments allow for shifting the balance of power between the propane compressor and the HP MR compressor to improve LNG production efficiency.

Disclosed herein is an integrated power generation and load driving system, comprising in combination a multi-shaft gas turbine engine comprising a high-pressure turbine mechanically coupled to an air compressor; and a low-pressure turbine, fluidly coupled to but mechanically separated from the high-pressure turbine and mechanically coupled to an output power shaft wherein the output power shaft is connected to a shaft line an electric generator, mechanically coupled to the shaft line and driven into rotation by the gas turbine engine a rotating load, mechanically coupled to the shaft line and driven into rotation by the gas turbine engine a load control arrangement, configured for controlling at least one operating parameter of the rotating load to adapt the operating condition of the rotating load to process requirements from a process, whereof the rotating load forms part, while the low-pressure turbine and the electric generator rotate at a substantially constant speed.

The compression train includes an engine, a first centrifugal compressor driven by the engine and a second centrifugal compressor driven by the engine; the first centrifugal compressor is housed inside one case; the second centrifugal compressor is housed inside one case; the first centrifugal compressor has a first inlet fluidly connected to a line of high molecular weight gas, in particular higher than 40; the second centrifugal compressor has a second inlet fluidly connected to a line of low molecular weight gas, in particular between 20 and 30; the second centrifugal compressor is arranged to provide a compression ratio higher than 10:1.