Methods and configurations for H2S concentration in acid gas removal
First Claim
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1. A method of treating an H2S- and CO2-containing syngas, comprising:
- absorbing in an absorber at syngas pressure H2S and CO2 from the H2S- and CO2-containing syngas using a lean physical solvent to so form a treated CO2-containing syngas and a rich solvent comprising H2S and CO2, wherein the lean physical solvent is a H2S selective physical solvent;
heating and flashing the rich solvent comprising H2S and CO2 in at least two successive flash stages to produce respective flash gases enriched in CO2 and respective flashed rich solvents comprising H2S, wherein the step of heating the rich solvent in the at least two stages uses heat from the lean solvent;
cooling the flash gases to form respective cooled flash gases and respective condensate streams, recycling the flash gases enriched in CO2 to the syngas or absorber and feeding the condensate streams into a stripper; and
regenerating the condensate streams and the flashed rich solvent comprising H2S in the stripper to so form the lean physical solvent and an H2S rich acid gas stream that has a CO2 content of at least 30 mol % and an H2S to CO2 ratio of at least 1.1;
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Abstract
A syngas treatment plant is configured to remove sulfurous compounds from syngas in a configuration having two flash stages for a physical solvent to so enrich the acid gas to at least 40 mol % H2S or higher as required by the Claus unit and to flash and recycle CO2 back to the syngas feed. Contemplated methods and configurations advantageously remove sulfur to less than 10 ppmv while increasing H2S selectivity at high pressure operation to thereby allow production of an H2S stream that is suitable as feed gas to a Claus plant.
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Citations
14 Claims
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1. A method of treating an H2S- and CO2-containing syngas, comprising:
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absorbing in an absorber at syngas pressure H2S and CO2 from the H2S- and CO2-containing syngas using a lean physical solvent to so form a treated CO2-containing syngas and a rich solvent comprising H2S and CO2, wherein the lean physical solvent is a H2S selective physical solvent; heating and flashing the rich solvent comprising H2S and CO2 in at least two successive flash stages to produce respective flash gases enriched in CO2 and respective flashed rich solvents comprising H2S, wherein the step of heating the rich solvent in the at least two stages uses heat from the lean solvent; cooling the flash gases to form respective cooled flash gases and respective condensate streams, recycling the flash gases enriched in CO2 to the syngas or absorber and feeding the condensate streams into a stripper; and regenerating the condensate streams and the flashed rich solvent comprising H2S in the stripper to so form the lean physical solvent and an H2S rich acid gas stream that has a CO2 content of at least 30 mol % and an H2S to CO2 ratio of at least 1.1;
1. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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Specification