Capturing acid compounds comprising carbon dioxide and hydrogen sulfide contained in e.g. natural gas, comprises contacting gas with absorbent solution, and regenerating fraction of absorbent solution enriched in acid compounds

摘要

The process comprises contacting the gas to be treated with an absorbent solution comprising an amine in aqueous solution to obtain a gas depleted in acid compounds and comprising amine and an absorbent solution enriched in acid compounds, regenerating a fraction of absorbent solution enriched in acid compounds in a regeneration column to obtain a regenerated absorbent solution and a gaseous effluent rich in acid compounds, and washing the resultant gas in a first washing section with a first liquid flow for obtaining a gas depleted in amine and a flow of water enriched in amine. The process comprises contacting the gas to be treated with an absorbent solution comprising an amine in aqueous solution to obtain a gas depleted in acid compounds and comprising amine and an absorbent solution enriched in acid compounds, regenerating a fraction of absorbent solution enriched in acid compounds in a regeneration column to obtain a regenerated absorbent solution and a gaseous effluent rich in acid compounds, washing the resultant gas in a first washing section with a first liquid flow for obtaining a gas depleted in amine and a flow of water enriched in amine, and washing the resulting gas in a second washing section with a second liquid flow comprising an acid whose dissociation constant (pKa) is lower than 6 for obtaining a treated gas and a water flow enriched in salts. A part of water enriched in amine and amine degradation products obtained in bottom of the first section is cooled and recycled for constituting a portion of the first liquid flow. The water flow enriched in amine is recycled by mixing the water flow with the regenerated absorbent solution, introducing the part of water flow in the regeneration column, and mixing the water flow with the regenerated absorbent solution enriched in acid compounds. The water flow enriched in salts is removed, and then distilled into fractions for obtaining vapor phase and liquid phase enriched in salts. A base such as sodium hydroxide and potassium is introduced in the fractions for neutralizing the salts.