Liquid desulfurizer

Due to proton transfer, the reaction between H2S and MDEA(N- methyldiethanolamine) is a transient chemical reaction controlled by gas membrane: H2S+R2NCH3=[R2NHCH3]+[HS]- As MDEA is a tertiary amine, CO2 reacts with amine for acid-base neutralization only after it forms bicarbonate with water: CO2+H2O+R2NCH3 R2NHCH3+HCO3 Because CO2 and water need a slow intermediate process, this huge difference in reaction rate forms the basis of selective absorption, that is, MDEA has higher selectivity for H2S absorption in the presence of CO2. The acidic tail gas is washed with water to remove CH3OH and HCN, and then enters the bottom of the absorption tower to make countercurrent contact with the lean amine liquid added from the top, and the purified gas after desulfurization escapes from the top of the absorption tower. The rich amine solution leaving the absorption tower is heated by exchanging heat with poor amine through the heat exchanger, and then regenerated in the regeneration tower. The removed regenerated acid gas containing H2S and CO2 is used as the feed of Claus plant, and the poor amine is pumped to the absorption tower by cooling.