Stepwise absorption of CO2 and sulfides in low-temperature methanol washing
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I’m a beginner and would like to understand how CO2 and sulfides are absorbed in stages during low-temperature methanol washing. After reading some materials, I’m still not very clear – is it methanol rich in CO2 that is used to absorb the sulfides?
Yes, first absorb carbon dioxide; the CO2-enriched methanol is then used to absorb hydrogen sulfide
Principle: It has a higher absorption capacity for hydrogen sulfide than for CO2. One refining section and one decarburization section; a portion of the methanol produced in the decarburization section can be used to achieve desulfurization. So desulfurization is done in the lower tower, and decarburization is done in the upper tower. The sulfur-free methanol, which still does not contain absorbed sulfur, coming out of the decarburization section is reabsorbed at the tops of towers 2 and 3, to ensure that the CO2 separated and the hydrogen sulfide in the exhaust gases meet the emission standards.
Thank you:handshake
I also want to know the specific implementation method
Thank you for the answer. I’m not sure what exactly you mean by towers 2 and 3
The use of CO2-enriched methanol to absorb sulfides is based primarily on the selectivity of solvent absorption; since H2S has a higher solubility in methanol than CO2, it is possible to absorb H2S in the lower column. Additionally, the heat of dissolution released during the absorption of H2S and COS in the lower column is compensated by the desorption heat of CO2 from methanol, thereby preventing an increase in temperature in the desulfurization section and facilitating the absorption of H2S and COS.