Aspen Plus simulation-based parametric study of Benfield process using hot potassium carbonate promoted by diethanolamine

Abstract

Simulating Benfield process that uses hot potassium carbonate as a chemical absorbent is a challenging task given the absence of the electrolyte system package in the more widely used simulation software such as Aspen Hysys and the fact that all of the existing simulation works have featured either the absorption column or the stripping column as a stand-alone process scenario. In this work, Benfield process is simulated using the Aspen Plus software as a whole process where the absorption column is integrated to the stripping column in a closed-loop mode. The chemical absorbent, i.e., hot potassium carbonate (K2CO3) is promoted by 3 wt.% of diethanolamine (DEA) to enhance the solubility of the carbon dioxide in the absorbent via higher reaction rate. The absorption column is simulated using rate-based approach while the stripping column is simulated using equilibrium approach. The simulation is validated against the industry data. The effects of stripping column boil-up ratio, solvent circulation rate, and K2CO3 concentration on the reboiler duty and the sweet gas CO2 concentration are studied. The lowest reboiler duty of 48 GCal h−1 and the lowest CO2 concentration of less than 50 ppmv are obtained using a boil-up ratio of 0.3, a solvent circulation rate of 35,000 kmol h−1, and K2CO3 concentration of 15 wt.%.