Processes and Device for Low Temperature Separation of Air

Abstract

Processes and a device for the low-temperature separation of air are provided. A main air stream is compressed in an air compressor at a first pressure and is then purified. A first air stream is further compressed at a second pressure. From the further compressed first air stream, a throttling stream and a turbine stream are branched off. The throttling stream is cooled down and liquefied or pseudo-liquefied for supply to an expansion device and is then conducted into a distillation-column system via the expanded throttling steam. The turbine stream is cooled down in the main heat exchanger, under an intermediate temperature of the main heat exchanger is conducted into an expansion machine, as well as works and expands. The worked expanded turbine stream is at least partially conducted to the distillation-column system. The liquid product flow is withdrawn, the liquid improves to an increased pressure, evaporates or pseudo-evaporates under the pressure, and is withdrawn as a gas state product flow. The turbine flow is cooled in a main heat exchanger so that dew-point temperature or low temperature is achieved when pressure of the turbine flow is sub-critical. The turbine flow liquefied or pseudo-liquefied or is expanded to intermediate pressure that lies between a first pressure and a second pressure. The expanded turbine flow in the main heat exchanger is heated to intermediate temperature before the turbine flow is fed to an expansion machine.

Description

technical field [0001] The invention relates to a method according to the preamble of claim 1 . Background technique [0002] These processes, in which a liquid pressurized product stream is evaporated against a heat carrier and finally recovered as a gaseous pressurized product, are also referred to as internal compression methods. It is used in particular to obtain pressurized oxygen, but it can also be used to obtain pressurized nitrogen or pressurized argon. The phase transfer does not take place in the true sense for supercritical pressure conditions in the main heat exchanger, so the product stream "pseudo-vaporizes". [0003] In the main heat exchanger, a partial flow of the heat carrier at high pressure, namely air, referred to here as "throttling flow", is liquefied against the (pseudo) vaporized product flow (or pseudo- liquefaction). [0004] It is customary here that the throttle flow and the turbine flow are raised together in a recompressor or in a main air ...

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Problems solved by technology

Higher liquid fraction can lead to turbine damage

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