Patent ID: 9433894
Filing Date: 2016-09-06
CPC Classification: B01D,C01D

Claim Text:
1. A method for removing hydrogen sulfide from a carbon dioxide gas stream in a soda ash production facility comprising introducing a H 2 S-contaminated carbon dioxide gas stream from a carbon dioxide stripping unit operation in a soda ash production facility containing at least 20 vol % CO2 into a gas absorption apparatus for sequential contact of the gas stream with a first absorber alkali stream in a first absorber section and with a second absorber alkali stream in a second absorber section, wherein the first absorber alkali stream is an aqueous alkali waste stream containing at least 1 wt. % Na 2 CO 3 and solubilized impurities from the soda ash production facility and is contacted with the H 2 S-contaminated carbon dioxide gas stream in the first absorber section of the gas absorption apparatus in an amount sufficient to absorb a substantial amount of the H 2 S from the gas stream to produce a H 2 S-depleted carbon dioxide gas stream and a first absorber effluent stream containing the absorbed H 2 S, and wherein the second absorber alkali stream is an aqueous process stream containing at least 1 wt. % Na 2 CO 3 from the soda ash production facility and is contacted with the H 2 S-depleted carbon dioxide gas stream in the second absorber section of the gas absorption apparatus in an amount sufficient to absorb a substantial amount of the residual H 2 S in the H 2 S-depleted carbon dioxide gas stream from the gas stream to produce a purified carbon dioxide gas stream and a second absorber effluent stream containing the absorbed residual H 2 S; withdrawing the first absorber effluent stream containing absorbed H 2 S and solubilized impurities from the first absorber section; withdrawing the second absorber effluent stream containing absorbed residual H 2 S from the second absorber section and thereafter utilizing the second absorber effluent stream in the soda ash production facility, for further processing for recovery of its solubilized Na 2 CO 3 values; and withdrawing the purified carbon dioxide gas stream from the gas absorption apparatus.