Balancing power in split mixed refrigerant liquefaction system

A system comprising:

• a precooling subsystem having a precooling compressor having at least one first refrigerant compression stage and at least one precooling heat exchanger, the precooling subsystem being adapted to cool a hydrocarbon feed stream by indirect heat exchange against a first refrigerant stream to produce a precooled hydrocarbon fluid stream;
• a liquefaction subsystem having a plurality of second refrigerant compression stages and at least one liquefaction heat exchanger, the liquefaction system being adapted to at least partially liquefy the precooled hydrocarbon stream by indirect heat exchange against a second refrigerant stream to produce a cooled hydrocarbon fluid stream;
• a first driver that drives the precooling compressor and at least one second refrigerant compression stage of the plurality of second refrigerant compression stages;
• a second driver that drives the remaining second refrigerant compression stages of the plurality of second refrigerant compression stages;
• means for changing a power requirement of the at least one second refrigerant compression stage;
• and
• a controller adapted to measure a first power state of the first driver and a second power state of the second driver and to control the power requirement of the at least one second refrigerant compression stage, the first power state of the first driver, the second power state of the second driver, and a flow rate of at least one selected from the group of the hydrocarbon feed stream and the precooled hydrocarbon stream;
• wherein when one of the first power state and the second power state is less than the maximum available power, the controller is adapted to adjust the means for changing the power requirement of the at least one second refrigerant compression stage, wherein the adjustment of the means for changing the power requirement of the at least one second refrigerant compression stage results in a reduction in a difference between the first power state and the second power state, an increase in a sum of the first power state and the second power state, and an increase in production of the precooled hydrocarbon fluid stream.

A method of operating a hydrocarbon fluid liquefaction system, the method comprising:

• a. precooling a hydrocarbon feed stream, being fed at a first flow rate, by indirect heat exchange with a precooling refrigerant stream and a precooled hydrocarbon fluid stream having a temperature within a first predetermined range;
• b. compressing the precooling refrigerant stream in a precooling compressor having at least one compression stage;
• c. further cooling and at least partially liquefying the precooled hydrocarbon stream by indirect heat exchange against a second refrigerant stream to produce a cooled hydrocarbon fluid stream having a temperature within a second predetermined range;
• d. compressing the second refrigerant stream in a compression sequence comprising a plurality of second refrigerant compression stages, the plurality of second refrigerant compression stages consisting of a first set of second refrigerant compression stages and a second set of second refrigerant compression stages;
• e. driving the precooling compressor and the first set of second refrigerant compression stages with a first driver;
• f. driving the second set of second refrigerant compression stages with a second driver;
• g. operating at least one of the first set of second refrigerant compression stages at a first power requirement that results in a first power differential between the first driver and second driver;
• h. adjusting the compression power requirement of at least one of the first set of second refrigerant compression stages, which results in a second power differential between the first driver and the second driver, the second power differential being less than the first power differential;
• and
• i. increasing the first flow rate of the hydrocarbon feed stream to a second flow rate either concurrently or after performing step (h), while maintaining the temperature of the precooled hydrocarbon fluid stream within the first predetermined range and the temperature of the cooled hydrocarbon fluid stream within the second predetermined range.