Figure 1 shows a simplified process flow diagram (PFD) of a typical methyl diethanolamine (MDEA)-based acid gas removal (AGR) process. It shows the typical process arrangement of chemical absorption processes, with acid gas in countercurrent flow with solvent in the trayed absorber column. Rich solvent is regenerated by steam stripping in the stripper column.
MDEA is frequently chosen for removal of sulfur from syngas, because it is a weak base that reacts much faster with hydrogen sulfide than with carbon dioxide, making it particularly selective under the proper design conditions. MDEA is used selectively on higher-pressure gas steams (20.6 barg and above) for deep hydrogen sulfide removal with only moderate carbon dioxide removal.
Syngas Clean Up