Study of CO2 absorption and desorption in a packed column

Carbon dioxide, a major greenhouse gas, may need to be removed from flue gas produced by combustion of fossil fuels in order to manage future climate changes. Although conventional wet scrubbing techniques exist for removal of carbon dioxide from gas streams, the wet scrubbing techniques must improve to process large volumes of flue gas at acceptable thermal efficiencies and minimal costs. Amine scrubbing is one such technique to remove CO2. To make the process more efficient, various areas of improvement were investigated: gas-liquid contacting area, the type of reactant, and dilution of the aqueous fraction with organic liquids. Pertaining to the former, various absorption tests with conventional packing material and structured packings were conducted with mono-ethanolamine (MEA), a traditional solvent, as well as with novel amines. Significant improvements in CO2 removal were obtained with the structured packing. With respect to the amine investigation, a key to improved efficiency is the ease of regeneration of the CO2-loaded absorbent. Testing with a sterically hindered amine, 2-amino-2-methyl-1-propanol, revealed that, although absorption was somewhat less as compared to MEA, thermal regeneration was far easier. In addition, the effect of organic diluent on CO2 absorption capacity of MEA solution is determined. The impact of various process parameters on the absorption and desorption steps will also be discussed.