A method for operating an air separation plant having a distillation column system, a heat exchanger, and an adsorber, wherein, in a first time period, a first operating mode is carried out and, in a second time period following the first time period, a second operating mode is carried out. In a third time period between the second time period and the first time period, a third operating mode is carried out, in which third operating mode compressed air is at least partially freed of water and carbon dioxide in the adsorber and at least part of said compressed air is cooled in the heat exchanger, an air product is removed from the distillation column system and at least part of said air product is heated in the heat exchanger.

Systems and methods for controlling a natural gas production system in an upset scenario, and/or during startup of turbo-expander system are disclosed. In one embodiment, a method of operating a Joule-Thomson valve of a natural gas production system includes determining an upset event within the natural gas production system, obtaining a flow rate through at least one expander prior to the upset event, and calculating, based on the flow rate, a percent opening of the Joule-Thomson valve. The method further includes opening the Joule-Thomson valve to the percent opening, controlling the Joule-Thomson valve by a PID controller in a set point tracking mode for a period of time, and controlling the Joule-Thomson valve by the PID controller in an automatic mode.

A method for handling the shutdown of a turbomachine string installed in a plant for the liquefaction of a gaseous product comprising at least two turbomachine strings comprises the steps of detecting the shutdown of a first turbomachine string; promptly increasing the driving torque on a shaft of a second turbomachine string when the shutdown is detected; maintaining the driving torque increase on the shaft of the second turbomachine string until a preset speed of the motor driver is reached or a predetermined period of time expires.

A method for operating a heat exchanger, in which a first operating mode is carried out in first time periods, and a second operating mode is carried out in second time periods that alternate with the first time periods; in the first operating mode a first fluid flow is formed at a first temperature level, is fed into the heat exchanger in a first region at the first temperature level, and is partially or completely cooled in the heat exchanger; in the first operating mode a second fluid flow is formed at a second temperature level, is fed into the heat exchanger in a second region at the second temperature level, and is partially or completely heated in the heat exchanger. A corresponding arrangement and a system with such an arrangement are also covered by the present invention.

A liquefied gas cooling apparatus including: a gas flow path for carrying a liquefied gas that is liquefied by cooling; and a refrigeration unit including a refrigerating cycle formed by an evaporator for cooling the liquefied gas flowing through the gas flow path, a compressor, a condenser, and a throttle expansion unit. The compressor is driven through an electric motor contained in a sealed housing together with a compressor mechanism.

A liquefied gas cooling apparatus includes: a gas flow path for carrying a liquefied gas that is liquefied by cooling; and a refrigeration unit including a refrigerating cycle formed by an evaporator for cooling the liquefied gas flowing through the gas flow path, a compressor, a condenser, and a throttle expansion unit. The refrigeration unit includes: an inlet-side open/close valve and an outlet-side open/close valve provided in an inlet path and an outlet path of the compressor, respectively; and a service open/close valve in a refrigerant path between the inlet-side open/close valve and the outlet-side open/close valve.

Disclosed is a low-temperature refrigeration device comprising a working circuit that forms a loop and contains a working fluid, the device further comprising a cooling exchanger for extracting heat from at least one member by exchanging heat with the working fluid, the working circuit forming a cycle comprising, connected in series: a compression mechanism, a cooling mechanism, an expansion mechanism and a heating mechanism, wherein the mechanism for cooling the working fluid and the heating mechanism comprise a common heat exchanger in which the working fluid flows in opposite directions in two separate transit portions of the circuit according to whether it is cooled or heated, the device being designed to ensure equal mass flow rates in the two transit portions in the common heat exchanger, the device also comprising a bypass for bypassing one of the two transit portions, said bypass comprising a bypass valve which, in the open state, changes the mass flow rate in one of the two transit portions.

A method of operating, during an at least partial shutdown of a refrigerant distribution subsystem in a natural gas liquefaction facility, can include: draining down at least a portion of a mixed refrigerant in one or more components of the refrigerant distribution subsystem into a high-pressure holding tank of a drain down subsystem, wherein draining down to the high-pressure holding tank is achieved by pumping the mixed refrigerant from the refrigerant distribution subsystem to the high-pressure holding tank or backfilling the refrigerant distribution subsystem with a backfill gas; and optionally, transferring at least a portion of the mixed refrigerant into a low-pressure drum from the high-pressure holding tank.

Disclosed is a refrigeration and/or liquefaction method using a system that includes a low-temperature refrigeration device comprising a working circuit which forms a loop and contains a working fluid, the working circuit forming a cycle comprising, connected in series: a compression mechanism, a cooling mechanism, an expansion mechanism and a heating mechanism the refrigeration device further comprising a cooling exchanger for extracting heat from the useful fluid stream by exchanging heat with the working fluid flowing in the working circuit, the system comprising a pipe through which the useful fluid stream flows in the cooling exchanger, the method comprising a cooling step in which the refrigeration device is in a first operating mode for cooling the cooling exchanger while a useful fluid stream flows in the cooling exchanger, the method comprising, after said cooling step, a step of cleaning impurities that have solidified in the cooling exchanger, characterized in that during the cleaning step, the refrigeration device is in a second operating mode in which the working gas flows in the working circuit but in which the cooling exchanger cools less intensely than in the first operating mode.

The invention relates to a method for cooling and/or liquefying a user fluid flow the method using a cooling and/or liquefying system comprising a low-temperature refrigeration device, the refrigeration device comprising a working circuit forming a loop and containing a working fluid, the refrigeration device comprising a cooling exchanger intended to extract heat from the user fluid flow by heat exchange with the working fluid circulating in the working circuit, the working circuit forming a cycle comprising, in a series: a compression mechanism a cooling mechanism, an expansion mechanism, and a reheating mechanism, the system comprising a pipe for circulation of the user fluid flow to be cooled in heat exchange with the cooling exchanger of the refrigeration device, the method comprising a step of cooling a user fluid flow in the cooling exchanger and after this cooling step, a step of cleaning impurities solidified in the cooling exchanger, the cleaning step comprising stopping of the refrigeration device and simultaneously, circulation of a user fluid flow in the cooling exchanger.