Gas absorption
First Claim
1. 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; and
f) recycling lean absorbent liquid from step e) to step b).
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Accused Products
Abstract
A double-loop process for the removal of specified gas or gases from a process gas by absorption with a liquid absorbent for said specified gas or gases wherein the process gas is contacted counter-currently in a first absorption stage with semi-lean absorbent liquid and then in a second absorption stage with lean absorbent liquid to give a sweet process gas and the absorbed gases are stripped from the laden absorbent liquid in a first stage giving a semi-lean absorbent liquid. Part of the semi-lean absorbent is recycled to the first absorption stage while the remainder is subjected to further stripping by counter-current contact with an auxiliary gas that has a concentration of the specified gas or gases that is lower than the concentration of the specified gas or gases in the process gas to give the lean absorbent liquid which is recycled to the second absorption stage. The auxiliary gas, which is especially a part stream of the sweet process gas, may be recycled, after use for stripping, to the process gas upstream of the first absorption stage. The process may be integrated with a glycol drying stage with regeneration of the wet glycol by stripping with the part stream of the sweet process gas before the latter is used for stripping the semi-lean absorbent liquid.
115 Citations
15 Claims
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1. A double-loop process for the removal of at least one specified gas from a process gas comprising:
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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; and f) recycling lean absorbent liquid from step e) to step b). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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Specification