Process and plant for separating a gaseous mixture by cryogenic distillation

摘要

A cryogenic distillation apparatus comprising a system of columns (9, 11) also includes at least one external source of a gas other than a column of the system and means for sending this pressurized gas to the first pump (17) in order to serve as barrier gas for a pump (17, 23, 25, 27) and/or at least one external source (20) of liquid other than a column of the system and means for vaporizing at least one portion of this liquid and for sending the vapour thus formed to the first pump in order to serve as barrier gas and/or means (3) for withdrawing a liquid from a column of the system and for vaporizing at least one portion thereof downstream of the first or of the second pump in order to deliver a barrier gas (21) for the first pump.