A propulsion system includes an electric fan propulsion motor with a plurality of propulsion motor windings. The propulsion system also includes a means for controlling a flow rate of a working fluid through a cryogenic working fluid flow control assembly to the propulsion motor windings.

The invention relates to a method for separating air by cryogenic distillation in a set of columns including a first column operating at a first pressure, a second column operating at a second pressure which is lower than the first pressure, and a third column operating at a third pressure, which is lower than the second pressure, wherein the third column includes first and second evaporator-condensers, and nitrogen from a cold compressor is sent to one of the evaporator-condensers.

A method and a device used to variably obtain a compressed-gas product by means of the low-temperature separation of air in a distillation column system. In a first operating mode, a first amount of first compressed-gas product is obtained, and, in a second operating mode, a second, smaller amount is obtained. In the first operating mode, a first amount of high-pressure column nitrogen is compressed in a nitrogen compressor and in the second operating mode, a second, larger amount is compressed in the nitrogen compressor.

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 method and apparatus for separating air in which production of the liquid products can be selectively varied between high and low production rates by varying the pressure ratio across a turboexpander used in imparting refrigeration with the use of a branched flow path. The branched flow path has a system of valves to selectively and gradually introduce a compressed refrigerant air stream into either a booster compressor branch having a booster compressor to increase the pressure ratio during high modes of liquid production or a bypass branch that bypasses the booster compressor to decrease the pressure ratio during low modes of liquid production. A recycle branch is connected to the booster compressor branch to allow compressed air to be independently recycled from the outlet to the inlet of the booster compressor during turndown from the high to the low liquid mode of liquid production to prevent surge.

A process and air separation plant for producing one or more air products by cryogenic separation of air in an air separation plant wherein a first fraction and a second fraction of feed air quantity are post-compressed in a post-compressor from a first pressure level to a second pressure level at least 3 bar above the first pressure level, and are extracted from a post-compressor jointly at the second pressure level, impure nitrogen, the nitrogen content of which lies below an overhead product of a high-pressure column, is extracted from the high-pressure column at the first pressure level and is expanded using a second turboexpander which is mechanically coupled to a first booster, and a fluid enriched with argon is extracted from a low-pressure column, is depleted of argon and is recycled into the low-pressure column.

A method is provided for production of gaseous oxygen at high pressures by splitting a main air feed into at least three separate streams, with the first stream being fed to a heat exchanger and then a column system for rectification; the second stream being further compressed in a warm booster, partially cooled in the heat exchanger, expanded in a turbine coupled to the warm booster and then fed to the column system; the third stream being expanded in a warm expander before being introduced to the heat exchanger and introduced to the column system. In certain embodiments, substantially all of the main air feed is eventually introduced to the column system for rectification, resulting in reduced sizing of a main air compressor and improved product recoveries.