Research Results for CO2 Capture from Flue Gas by Aqueous Absorption/Stripping

摘要

Alkanolamine absorption/stripping is an important technological option for CO2 sequestration to address global climate change. It has long been a commercial technology for CO2 removal from natural gas and hydrogen. Along with other technical challenges, application of this technology to coal combustion gases must address lower CO2 partial pressures, large gas flow rates, and solvent oxidation. Commercial systems using monoethanolamine (MEA) require potentially prohibitive quantities of steam for stripping. Solvents with a reduced heat of desorption have mixed benefits because they may also increase the stripping steam required, depending on the process configuration. An optimum design will probably have pinches at the lean and rich ends of the absorber and stripper. Piperazine is an effective rate promoter of CO2 absorption in potassium carbonate solvents. These solvents can have rates and capacities comparable to MEA, but with heats of desorption of 50 to 75% of that in MEA. Oxidative degradation of MEA is catalyzed by dissolved iron and dissolved copper with maximum rates in air at 60oC of about 2 mM ammonia/hr. The catalysis by copper is inhibited by EDTA.