A method is proposed for compressing a gas in stages in a compressor arrangement (100, 200, 300, 400) having a plurality of compression stages (I-VI) which are connected together sequentially by a main line (1) and in which the gas, guided through the main line (1), is respectively compressed from a suction-side pressure level to a pressure-side pressure level and is heated by this compression from a suction-side temperature level to a pressure-side temperature level, wherein a feedback amount of the gas, guided through the main line (1), is at least temporarily removed from the main line (1) downstream of one of the compression stages (V), is fed to an expansion process, and is fed back into the main line (1) upstream of the same compression stage (V). It is provided that the pressure-side pressure level of the compression stage (V) downstream of which the feedback amount is removed from the main line (1) is a supercritical pressure level, that the feedback amount is expanded to a subcritical pressure level, that the feedback amount is fed to the expansion process at the pressure-side temperature level of the compression stage (V) downstream of which it is removed from the main line (1), and that the feedback amount is cooled only after being expanded and before and/or after being fed back into the main line (1). The invention also relates to a compressor arrangement (100, 200, 300, 400).

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.

A method for producing ethylene and/or other olefins by steam cracking includes charging one or more crackers with a paraffin-containing feed and withdrawing a crude gas from the one or more crackers. The crude gas is subjected at least in part to a treatment comprising a crude gas compression and a thermal separation using a C2 refrigerant and a C3 refrigerant. A crude gas compressor is used for the crude gas compression, wherein the ethylene refrigerant is compressed using a C2 refrigerant compressor. The propylene refrigerant is compressed using a C3 refrigerant compressor. The crude gas compressor comprises two serial compressor trains. The compressor trains, the C2 refrigerant compressor and the C3 refrigerant compressor are each operated at least in part using electrical drives, which have at least partially identical performance features, are provided as structurally identical variable-speed drives, and are each fed via frequency converters.

A drive system for liquefied natural gas (LNG) production. A standardized machinery string consisting of a multi-shaft gas turbine with no more than three compressor bodies, where the compressor bodies are applied to one or more refrigerant compressors employed in one or more refrigerant cycles (e.g., single mixed refrigerant, propane precooled mixed refrigerant, dual mixed refrigerant). The standardized machinery strings and associated standardized refrigerators are designed for a generic range of feed gas composition and ambient temperature conditions and are installed in opportunistic liquefaction plants without substantial reengineering and modifications. The approach captures D1BM (Design 1 Build Many) cost and schedule efficiencies by allowing for broader variability in liquefaction efficiency with location and feed gas composition.

A cooling system is provided for cooling a motor that drives a compressor in a liquefaction system. The coolant used for cooling the motor includes portions of a discharge from a compressor. The coolant for the motor is generated from a vapor component of the discharge from the compressor. The discharge from the compressor is cooled and the vapor component is separated from a liquid component and treated prior to being introduced into the motor. Remaining portions of the discharge from the compressor are routed to cold boxes producing a compressed refrigerant.

An apparatus for separation of air by cryogenic distillation comprising: a system of columns; a first turbine; a warm compressor coupled to the first turbine; a second turbine; a cold compressor coupled to the second turbine; a heat exchanger; means for sending air cooled in the heat exchanger at an intermediate temperature of the heat exchanger to the cold compressor; means for sending expanded air from the second turbine to the system of columns; means for sending air compressed in the cold compressor to an intermediate point of the heat exchanger and then at least in part to the system of columns via a first valve; means for sending air compressed in the cold compressor to the inlet of the first turbine via a second valve without passing through the heat exchanger, wherein the means for sending air compressed in the cold compressor to the inlet of the first turbine via the second valve without passing through the heat exchanger is also connected to the inlet of the first turbine; means for sending a fraction of air cooled in the heat exchanger to an intermediate temperature of the latter to the first turbine; means for sending expanded air from the first turbine to the system of columns; and a bypass line provided with an expansion valve configured to send air from the cold compressor to the system of columns without passing through the heat exchanger.

Method for separating air by cryogenic distillation in an air separation device comprising a system of columns, a first turbine and a second turbine, wherein, in de-icing operation, a common duct bringing air from the two turbines to a column is closed by means of an isolation valve, a purge gas is sent to the turbines at a temperature above 0 C. in order to de-ice them, but purge gas is not sent to the system of columns.

Method for separating air by cryogenic distillation, wherein at least part of the air to be distilled is boosted in an air booster, compressed air is allowed to expand in at least one expansion turbine and, if the pressure drop between two points of the booster passes under a threshold and/or a flow of the booster passes under a minimum flow of the booster, part of the air boosted in the booster is allowed to expand without having been cooled between the booster and the expansion turbine and the boosted expanded air is sent upstream or downstream of the at least one turbine, without having been cooled in the heat exchanger, after having been boosted.

Method for separating air by cryogenic distillation, wherein air is compressed in a compressor and is subsequently sent to a heat exchanger, with the air cooled in the exchanger being sent to a check valve downstream of the heat exchanger and subsequently to a turbine, the valve being positioned so that air from a short-circuiting duct cannot return to the exchanger from the compressor.

A boil-off gas supply device is provided with: a storage tank configured to store a liquefied gas; a first compression mechanism configured to suck in the boil-off gas of the liquefied gas stored in the storage tank and compress the sucked boil-off gas; a second compression mechanism configured to compress the boil-off gas after being compressed by the first compression mechanism; a discharge path in which the boil-off gas discharged from the second compression mechanism flows; a first drive source configured to drive the first compression mechanism; and a second drive source that is different from the first drive source and configured to drive the second compression mechanism.