Process and unit for producing oxygen by adsorption with a short cycle
AssigneeL'Air Liquide, Societe Anonyme pour l'Etude et l'Exploitation des Procedes Georges Claude
InventorsNathalie Derive, Anne Dubois, Christian Monereau
Life of this patent
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Abstract
The cycle employed is of the transatmospheric type with the use of a production buffer tank (C1), and with a purge/elution phase close to the low pressure in which gas output by another adsorber in the first cocurrent decompression phase is introduced in countercurrent into the adsorber (A, B) and, simultaneously, the countercurrent pumping is continued. During the production step, the oxygen produced is also sent into an auxiliary tank (C2), and the gas contained in this auxiliary tank is, with regard to the adsorber, used solely during a fraction of the pressurization phase of the adsorber.
Claims11
A process for producing oxygen from air by transatmospheric pressure swing adsorption, using a unit having at least two adsorbers, a cycle of duration T being implemented in each adsorber, the process comprising successively and cyclically:
- a phase of pressurization to a high pressure of the cycle using production oxygen introduced in countercurrent and/or air introduced in cocurrent, said phase ending with a cocurrent production step in which the oxygen produced is sent to a buffer volume;
- a first cocurrent decompression phase;
- a countercurrent purge phase comprising pumping to a low pressure of the cycle;
- and
- a purge/elution phase in which gas output by another adsorber in the first cocurrent decompression phase is introduced in countercurrent and, simultaneously, countercurrent pumping is continued;
- wherein the buffer volume is subdivided into a buffer tank and into an auxiliary volume comprising an auxiliary pressurization tank, during an initial part of the production step, the oxygen produced is sent only into the auxiliary pressurization tank, and the gas contained in the auxiliary pressurization tank is, with regard to the adsorber, used solely during a fraction of the pressurization phase of the adsorber.
Apparatus for producing oxygen from air by transatmospheric pressure swing adsorption, comprising at least two adsorbers in parallel which are selectively connected to an air compressor, to a vacuum pump and to a buffer production tank, outlets of the adsorbers being connected in pairs by a duct provided with a flow control valve;
- the apparatus further comprising at least one auxiliary pressurization tank, means for selectively connecting said auxiliary pressurization tank to the outlet of each adsorber, and means which are intended to connect the auxiliary pressurization tank to the buffer tank and are designed to set the auxiliary pressurization tank and the buffer tank in communication when, and only when, the pressure of the auxiliary pressurization tank is at least equal to that of the buffer tank.
Dependencies are inferred from the claim text.