Process and device for regenerating the loaded scrubbing agent in a physical gas wash
For regenerating the loaded washing (scrubbing) agent ( 6, 7 ) from a physical gas wash (T 1 ), in which one or more gas components are removed, to a large extent selectively, from a gas mixture ( 1 ) to be purified at least in a first of at least two successive washing steps, the loaded washing agent ( 7 ) withdrawn from the first washing step is, independently of the remaining quantity of loaded washing agent ( 6 ), subjected to a regeneration step (T 2 a ) for separating the gas components ( 11 ) which have been selectively removed from the raw gas in the first washing step.
1. A process for regenerating loaded washing agent from a physical gas wash, said loaded washing agent comprising
methanol, hydrogen cyanide and sour gases, said process comprising
in a scrubbing column, separating hydrogen cyanide (HCN) from a raw synthesis gas in a first washing step with a washing agent comprising methanol and dissolved sour gases,
separating remaining sour gases and/or carbon dioxide from said raw synthesis gas in at least one subsequent washing step by liquid cryogenic methanol, said liquid cryogenic methanol being used in a major amount compared to a minor amount being used in said first washing step, and withdrawing said major amount containing said remaining sour gases and/or carbon dioxide from the scrubbing column,
withdrawing a methanol washing agent loaded with HCN from the methanol wash and expanding into a stripping column independently of the remaining quantity of loaded washing agent,
generating a gas stream containing HCN by stripping in the stripping column, and
feeding said gas stream to a Claus plant and combusting therein.
2. A process according to claim 1 , wherein steam generated by boiling a sump product of the stripping column is used as stripping gas.
3. A process according to claim 1 , wherein the withdrawn methanol washing agent loaded with HCN is from the first washing step.
4. A process according to claim 1 , wherein the liquid cryogenic methanol that separated sour gases and/or carbon dioxide is regenerated.