A nitrogen generating method for producing product nitrogen using a nitrogen generating device comprising a main heat exchanger for cooling feed air, a nitrogen rectification column into which the feed air cooled in the main heat exchanger is introduced, and a nitrogen condenser which condenses a vapour stream fed from the nitrogen rectification column and circulates the same to the nitrogen rectification column, the method including a control step for discharging liquid nitrogen condensed by the nitrogen condenser and stored in a liquid nitrogen buffer, which is provided in an upper gas phase portion of the nitrogen rectification column or separately from the nitrogen rectification column, to a rectification portion of the nitrogen rectification column in response to an increase in an amount of product nitrogen or an increase in a flow rate of the feed air.

A method for determining an operating condition of a liquefied natural gas plant (2) includes preparing a training model (88) generated by machine learning using training data in which operating conditions data including a composition of a feed gas, a composition of a mixed refrigerant, and an ambient temperature and operation result data including a production efficiency of a liquefied product containing liquefied natural gas and a heavy component of the feed gas are associated together; and determining, as one new operating condition, a composition of the mixed refrigerant that optimizes a production efficiency of the liquefied natural gas predicted by the training model (88) from a latest composition of the feed gas in the liquefied natural gas plant (2) and a latest ambient temperature.

A system has a gas processing plant having a compressor, at least one natural gas liquids (NGL) train fluidly coupled to the compressor to receive mixed natural gas liquids from the gas processing plant, a valve fluidly coupling the gas processing plant to the at least one natural gas liquids train, and a control system coupled to the gas processing plant, the at least one natural gas liquids train, and the valve. The control system determines when to actuate the valve using a virtual sensing system based on a compressor shutdown condition, a compressor trip condition, a compressor recycle condition, an exclusion switch, a flow rate of the compressor, a running flow capacity of the first compressor, a required bypass flow of the compressor, and bypass flow distribution of the at least one natural gas liquids train.

A cryogenic air rectification system comprising a high pressure column, a low pressure column and an argon removal unit coupled to a condenser evaporator, wherein the system is configured to pass gas from a position above an oxygen section of the low pressure column as an argon removal feed gas to a lower region of the argon removal unit, wherein the system is configured to condense gas from an upper region of the argon removal unit in the condenser evaporator to form a condensate, wherein the system is configured to pass further gas from the top of the upper region of the argon removal unit out of the system, and wherein the system is configured to pass at least a part of the condensate as a reflux to the upper region of the argon removal unit.

Methods and systems include, using a monitoring system, initiating a control logic configured to control a production control system pertaining to a refrigeration system connected to a plurality of production trains. The method may include obtaining a plurality of production parameters; calculating, using the plurality of production parameters, an isentropic efficiency value for the primary compressor if the production flow rate is less than a production threshold; comparing each of the plurality of isentropic efficiency values; determining from the comparing each of the plurality of isentropic efficiency values, a primary compressor having a lowest isentropic efficiency value; selecting the respective primary compressor having the lowest isentropic efficiency value. The method may include, using a production control system, shutting down the selected primary compressor.

The invention relates to a plant and a method for producing liquefied hydrogen comprising a hydrogen gas generator, a liquefier, a feed line connecting an outlet of the hydrogen gas generator to an inlet of the liquefier, the liquefier comprising a refrigerator having a cycle circuit to cool the hydrogen gas from the feed line, the plant comprising a buffer store configured to store the compressed hydrogen gas between the hydrogen gas generator and the liquefier, the liquefier being configured to supply a cooling power and/or the liquefaction capacity that can be modified between at least two levels, the plant comprising a means for determining the fill level of the buffer store, the plant being configured to modify the cooling power and/or liquefaction capacity of the liquefier as a function of the fill level of the buffer store determined by the determining means.

Methods for managing natural gas liquids (NGL) recovery systems may comprise receiving a dryout gas by at least one first exchanger, the at least one first exchanger being part of a first NGL recovery train; receiving the dryout gas from the at least one first exchanger by a first dehydrator; receiving the dryout gas from the first dehydrator by at least one second exchanger, the second exchanger being part of a second NGL recovery train; receiving the dryout gas from the at least one first exchanger and the at least one second exchanger by a third exchanger; and bypassing a flare burner by directing the dryout gas from the third exchanger to a gas sales compressor through a first bypass fluid conduit.

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.

Systems and methods for recovering natural gas liquids include a distillation column; a thermosyphon reboiler fluidly connected to the distillation column; a Joule-Thomson valve fluidly connected to the distillation column and operable to control a flow of fluid into the distillation column; and a lift gas control valve operable to control a flow of lift gas into the distillation column through a return line of the thermosyphon reboiler. An interlock system operatively couples the Joule-Thomson valve and the lift gas control valve to operate the lift gas control valve in response to operation of the Joule-Thomson valve.

A reflux rate of a demethanizer is dynamically controlled. An ethane content of a hydrocarbon feed stream, a residue stream, and a bottoms stream are used by a controller to determine an ethane recovery value. The hydrocarbon feed stream includes methane, ethane, and propane and is fractionated by the demethanizer. The residue stream includes ethane. The bottoms stream includes propane. The controller controls the flow of reflux to the demethanizer, such that the determined ethane recovery value is equal to or greater than a specified target ethane recovery set point. The controller determines an objective value as a ratio of power consumption to the determined ethane recovery value. The controller controls the amount of cooling provided to the hydrocarbon feed stream, thereby adjusting power consumption and reducing the objective value while maintaining the ethane recovery value at or above the specified target ethane recovery set point.