Process for purifying synthesis gas by washing with aqueous solutions of amines
AssigneesAvril, Axens, Ifp Energies Nouvelles, Bionext, Thyssenkrupp Industrial Solutions AG, Total Raffinage Chimie, Commissariat A L'energie Atomique Et Aux Energies Alternatives
InventorsDavid Chiche, Anne Claire Pierron, Norbert Ullrich
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Abstract
The invention relates to a process for purifying synthesis gas, comprising at least one stage for separating the crude synthesis gas to be treated into at least two effluents, namely a first part and a complementary part, in which the said first part is subjected to a carbon monoxide conversion stage with steam and the said complementary part is subjected to a COS and HCN catalytic hydrolysis stage, the two gas flows, namely the first part and complementary part, are then each treated separately in two stages intended to remove acid gases such as CO2 and H2S, by washing with aqueous solutions of specific amines, before a recombination stage of the two treated effluents.
Claims24
A process for purification of synthesis gas, comprising at least the following stages:
- a) a stage for dividing the synthesis gas into at least a first synthesis gas flow and a second synthesis gas flow of the same composition,
- b1) a stage for the steam conversion of carbon monoxide of the first synthesis gas flow leaving stage a), in order to produce a stage b1) gaseous effluent containing at least hydrogen H2 and carbon dioxide CO2, less than 15% volume (vol. %) of carbon monoxide CO and acid gases including H2S and CO2,
- b2) a stage for the removal of acid gases including H2S and CO2 from the stage b1) gaseous effluent by contacting said stage b1) gaseous effluent with a solvent which is a first aqueous solution of amines comprising at least one secondary amine, said first aqueous solution of amines further comprising at least one tertiary amine or a sterically hindered secondary amine different from the secondary amine and containing at least one quaternary carbon atom in the α or alpha position of the nitrogen atom or two tertiary carbon atoms in the α and α′ positions, so as to remove acid gases including H2S and CO2 and produce at least one stage b2) gaseous effluent containing less than 5 vol. % of carbon dioxide CO2, and less than 50 ppm by volume of H2S,
- c1) a stage for catalytic hydrolysis of COS and HCN present in the second synthesis gas flow that has not undergone the conversion reaction of carbon monoxide with steam, in order to produce a stage c1) gaseous effluent containing less than 25 ppm by volume of COS, and less than 5 ppm by volume of HCN, and containing acid gases including H2S and CO2,
- c2) a stage for removal of acid gases including H2S and CO2 from said stage c1) gaseous effluent by contacting said stage c1) gaseous effluent with a solvent which is a second aqueous solution of amines containing at least one tertiary amine, so as to produce at least one stage c2) gaseous effluent containing less than 10 vol. % of carbon dioxide CO2, and less than 50 ppmv of H2S, wherein the second aqueous solution of amines contains between 25 and 50 wt. % of a tertiary amine and contains between 50 and 75 wt. % of water, and
- d) recombination of at least a part of said stage b2) effluent and at least part of said stage c2) to obtain a purified synthesis gas,
- wherein said first aqueous solution of amines and said second aqueous solution of amines are different.
A process for purification of synthesis gas, comprising at least the following stages:
- a) a stage for dividing the synthesis gas into at least a first synthesis gas flow and a second synthesis gas flow of the same composition,
- b1) a stage for the steam conversion of carbon monoxide of the first synthesis gas flow leaving stage a), in order to produce a stage b1) gaseous effluent containing at least hydrogen H2 and carbon dioxide CO2 and acid gases including H2S and CO2,
- b2) a stage for the removal of acid gases including H2S and CO2 from the stage b1) gaseous effluent by contacting said stage b1) gaseous effluent with a solvent which is a first aqueous solution of amines comprising at least one secondary amine, said first aqueous solution of amines further comprising at least one tertiary amine or a sterically hindered secondary amine different from the secondary amine and containing at least one quaternary carbon atom in the α or alpha position of the nitrogen atom or two tertiary carbon atoms in the α and α′ positions, so as to produce at least one stage b2) gaseous effluent,
- c1) a stage for catalytic hydrolysis of COS and HCN present in the second synthesis gas flow that has not undergone the conversion reaction of carbon monoxide with steam, in order to produce a stage c1) gaseous effluent containing acid gases COS and HCN,
- c2) a stage for removal of acid gases including H2S and CO2 from said stage c1) gaseous effluent by contacting said stage c1) gaseous effluent with a solvent which is a second aqueous solution of amines containing at least one tertiary amine, so as to produce at least one stage c2) gaseous effluent, wherein the second aqueous solution of amines contains between 25 and 50 wt. % of a tertiary amine and contains between 50 and 75 wt. % of water, and
- d) recombination of at least a part of said stage b2) effluent and at least part of said stage c2) to obtain a purified synthesis gas,
- wherein said first aqueous solution of amines is sensitive to the presence of CO and said second aqueous solution of amines is insensitive to the presence of CO.
Dependencies are inferred from the claim text.