Experimental Evaluation of Temperature and Concentration Effects on Heat of Dissociation of CO2-loaded MEA Solution in Strippers

Abstract

Regeneration heat in strippers of CCS system is affected by operating temperature and concentration of amine solutions and accurate measurement, modelling and prediction of it are necessary to design the strippers with selecting new or blend amine solutions. This paper reports the heat of dissociation of CO2-loaded 30wt% monoethanolamine (MEA) solution quantified experimentally by a small-scale apparatus circulating the solution through absorber and stripper. This method can quantify total regeneration heat as well as breakdown of regeneration heat consisted of the heat of CO2 dissociation, the sensible heat of solution and the latent heat of condensed water simultaneously. The heat of CO2 dissociation agreed well with the heat of CO2 absorption at 120 degrees C in literatures. Aspen Plus offers an example file of rate-based CCS system using MEA, and the process flow diagram (PFD) was developed to simulate the apparatus by using it. The developed PFD with the original electrolyte NRTL model underestimated heat duty of the stripper. We modified temperature dependency of the specific heat capacity of protonated MEA. The modified model could predict accurately the heat of CO2 dissociation as well as mole fraction of chemical species, while effect of solution concentration on the heat of CO2 absorption was still not sufficiently simulated.