The present techniques are directed to a flexible liquefied natural gas (LNG) plant that may be tied to an external electric grid for importing or exporting electric power. Exemplary embodiments provide a method for producing LNG that includes producing a base load capacity of refrigeration capacity for LNG production from a first compression system. Electricity may be produced from a second compressor string if electricity is needed by an external power grid, or a second amount of refrigeration capacity may be provided by the second compressor string is natural gas feed is available and the external grid does not need power.

A mixed phase pressurized unstabilized hydrocarbon stream is fed into a stabilizer column at a feed pressure. A liquid phase of stabilized hydrocarbon condensate is discharged from a bottom end of the stabilizer column, while a vapor phase of volatile components from the pressurized unstabilized hydrocarbon condensate stream is discharged from a top end of the stabilizer column. The vapor phase being discharged from the top end of the stabilizer column is compressed and subsequently passed through an ambient heat exchanger wherein partial condensation takes place. The resulting partially condensed overhead stream is separated in an overhead separator into a vapor effluent stream and an overhead liquid stream. After discharging the overhead liquid stream from the overhead separator, it is selectively divided into a liquid reflux stream and a liquid effluent stream. The liquid reflux stream is expanded to the feed pressure and fed into the stabilizer column.

A method for compression of an incoming feed air stream using at least two variable speed compressor drive assemblies controlled in tandem is provided. The first variable speed drive assembly drives at least one compression stage in the lower pressure compressor unit driven while the second variable speed drive assembly drives higher pressure compression stage disposed either in the common air compression train or the split functional compression train of the air separation plant. The first and second variable speed drive assemblies are preferably high speed, variable speed electric motor assemblies each having a motor body, a motor housing, and a motor shaft with one or more impellers directly and rigidly coupled to the motor shaft via a sacrificial rigid shaft coupling.

A method for compression of an incoming feed air stream using at least two variable speed compressor drive assemblies controlled in tandem is provided. The first variable speed drive assembly drives at least one compression stage in the lower pressure compressor unit driven while the second variable speed drive assembly drives higher pressure compression stage disposed either in the common air compression train or the split functional compression train of the air separation plant. The first and second variable speed drive assemblies are preferably high speed, variable speed electric motor assemblies each having a motor body, a motor housing, and a motor shaft with one or more impellers directly and rigidly coupled to the motor shaft via a sacrificial rigid shaft coupling.

A method for compression of an incoming feed air stream using at least two variable speed compressor drive assemblies controlled in tandem is provided. The first variable speed drive assembly drives at least one compression stage in the lower pressure compressor unit driven while the second variable speed drive assembly drives higher pressure compression stage disposed either in the common air compression train or the split functional compression train of the air separation plant. The first and second variable speed drive assemblies are preferably high speed, variable speed electric motor assemblies each having a motor body, a motor housing, and a motor shaft with one or more impellers directly and rigidly coupled to the motor shaft via a sacrificial rigid shaft coupling.

A gas processing system according to an embodiment of the present invention includes a heater which is configured to increase a temperature of liquefied gas compulsorily vaporized by a forcing vaporizer before the liquefied gas is joined with Boil Off Gas (BOG) compressed by a BOG compressor.

A system for removing freezing components from a feed gas includes a heavy hydrocarbon removal heat exchanger and a scrub device. The scrub device includes a scrub column that receives a cooled feed gas stream from the heat exchanger and a reflux separation device. Vapor from the scrub column is directed to the heat exchanger and cooled to create a reflux stream that includes a liquid component. This reflux stream is directed to the reflux separation device and a resulting liquid component stream is used to reflux the column. Vapor from the reflux separation device is expanded and directed to the heat exchanger, where it provides refrigeration, and a processed feed gas line.

A method for controlling flow in a Natural Gas Liquids (NGL) extraction system includes determining an operational characteristic of one or more residue gas compressors operating within the NGL extraction system and calculating a rate of closure for one or more throttle valves associated with the one or more residue gas compressors based on the operational characteristic determined. When a process upset in the NGL extraction system is detected, the one or more throttle valves are closed at the calculated rate of closure in response to detecting the process upset.

A system for removing freezing components from a feed gas includes a heat exchanger, a scrub column and a return vapor expansion device. The heat exchanger includes a reflux cooling passage and a return vapor passage. Vapor from the scrub column is directed through the return vapor expansion device, where the temperature and pressure are lowered. The resulting cooled fluid then travels to the return vapor passage of the heat exchanger and is used to cool a vapor stream in the reflux cooling passage to create a reflux fluid stream that is directed to the scrub column.

A system for liquefying a gas includes a liquefaction heat exchanger having a feed gas inlet adapted to receive a feed gas and a liquefied gas outlet through which the liquefied gas exits after the gas is liquefied in the liquefying passage of the heat exchanger by heat exchange with a primary refrigeration passage. A mixed refrigerant compressor system is configured to provide refrigerant to the primary refrigeration passage. An expander separator is in communication with the liquefied gas outlet of the liquefaction heat exchanger, and a cold gas line is in fluid communication with the expander separator. A cold recovery heat exchanger receives cold vapor from the cold gas line and liquid refrigerant from the mixed refrigerant compressor system so that the refrigerant is cooled using the cold vapor.