Effect of SO2 on the amine-based CO2 capture solvent and improvement using ion exchange resins

An amine-based CO2 capture solvent is developed to reduce energy requirement. Three campaigns, with 12 vol% CO2 and 18 vol% O-2, are conducted in a CO2 capture pilot plant to evaluate energy consumption and influence of SO2 on solvent characteristics, under the condition of prolonged operation. Monoethanolamine (MEA) is used in one campaign, and the other two campaigns employed new solvent, with and without 200 ppm SO2 in the simulated flue gas. The lost of free amine, including CO2 combines with amine (CCA), SO2 combines with amine (SCA) and amine degradation (AD), is analyzed. Experimental results show that the average energy consumption of MEA and novel absorbent is about 4.09 GJ/tCO(2) and 2.96 GACO(2), respectively. This value climbs to 3.51 GJ/tCO(2) for novel absorbent, with 200 ppm SO2. Meanwhile, the pH is reduced, the viscosity increases and free amine is lost more, which reduces the overall CO2 reaction rate and the overall mass transfer coefficient. The presence of SO2 increases SCA and AD, and decreases CCA. The SCA becomes main factor after running 200 h. An industrial strong-alkaline anion exchange resin through several runs is used to decrease the SCA and improve the solvent characteristics. The heat stable salts (HSS), including formate, oxalate, glycolate, sulfite and sulfate, can be reduced to less than 1 wt% by using the ion exchange resin. The solvent viscosity after treatment is only one tenth of the original solvent at 313 K. The overall mass transfer coefficient KG after treatment is about 1.7 times that without treatment. (C) 2015 Elsevier Ltd. All rights reserved.