Impact of heat stable salts on equilibrium CO2 absorption

Vapor liquid equilibrium measurements were carried out in the temperature range 40 - 120 degrees C for aqueous 30% MEA solution for a fresh solution, solutions containing 0.24mol/kg artificial heat stable salts (HSS)(sulfate, acetate, formate); and solutions from pilot plant containing real HSS (of concentrations 0.12, 0.24 and 0.35 mol/kg). All solutions are aqueous containing MEA of alkalinity 4.91 mol/kg. The solutions gave similar CO2 partial pressures at a given temperature and CO2 loading. Solutions from pilot plant that contains MEA + real HSS showed somewhat increased CO2 partial pressure and were particularly slow to attain equilibrium. Existing VLE model for 30% MEA adequately represent the experimental data from fresh 30% MEA and 30% MEA + artificial HSS without any adjustment to the model. The existing model does not represent the VLE of 30% MEA + real HSS solution adequately. A correction factor of 1.3 applied to the pCO(2) of the 30% MEA model was sufficient for adequate representation. The highly degraded level of the 30% MEA + real HSS solutions makes it unrealistic for a typical process. The solutions containing 30% MEA + artificial HSS mixture give a more realistic representation of liquid used in a typical process for CO2 capture; the VLE of these solutions is adequately represented by the existing model without adjustment. (C) 2013 The Authors. Published by Elsevier Ltd.