Patent ID: 6139605
Filing Date: 2000-10-31
Classification: B01D

Abstract:
A double-loop process for the removal of at least one specified gas from a process gas comprising:a) in a first absorption stage, contacting a stream of process gas counter-currently with a stream of an absorbent liquid that is capable of selectively absorbing the specified gas from the process gas whereby the specified is absorbed from said process gas to give a stream of partially sweetened process gas having a decreased concentration of said specified and a stream of loaded absorbent liquid;b) in a second absorption stage, contacting said partially sweetened process gas counter-currently with a stream of lean absorbent liquid whereby a further amount of said specified gas is absorbed from the partially sweetened process gas to give a sweet process gas having a further decreased concentration of said specified gas and a stream of partially loaded absorbent liquid;c) subjecting the loaded absorbent liquid stream from step a) to partial regeneration by counter-current contact of said loaded absorbent liquid with vapour obtained by vaporising absorbent liquid whereby the specified gas is stripped from said loaded absorbent liquid to give a semi-lean absorbent liquid stream;d) using partially loaded absorbent liquid from step b) as part of the absorbent liquid stream employed in step a) and part of the semi-lean absorbent liquid from step c) as the rest of the absorbent liquid stream employed in step a);e) subjecting the remainder of said semi-lean absorbent liquid stream from step c) to a further regeneration stage by counter-current contact of said part of the semi-lean absorbent liquid stream with an auxiliary gas stream that is part of the sweet process gas or is a gas used in the production of the process gas, said auxiliary gas having a concentration of the specified gas that is lower than the concentration of the specified gas in the process gas, thereby producing a stream of lean absorbent liquid and a gas stream containing the specified gas stripped from said semi-lean absorbent liquid; andf) recycling lean absorbent liquid from step e) to step b).