Optimum heat of absorption for CO2 capture using the advanced flash stripper

Abstract

Solvent selection is one of the promising ways to reduce energy use of amine scrubbing for CO2 capture. The heat of CO2 absorption is an important property of the solvent. Its effect on total energy use is not obvious: it directly increases the heat duty of regeneration, but indirectly reduces stripping steam and compression work. The optimum heat of absorption was quantified using the approximate stripper models developed in this work, including one of the most promising alternatives, the advanced flash stripper. Total equivalent work was used to indicate the overall energy performance. A wide range of lean loading, reboiler temperature, and compression efficiency was investigated. The optimum heat of absorption is 70–125kJ/mol CO2 at various conditions, which is generally higher than existing solvents with 60–80kJ/mol. Operation at low lean loading and low reboiler temperature requires higher heat of absorption to boost the partial pressure of CO2. The advanced flash stripper requires lower heat of absorption than the simple stripper to achieve minimum total equivalent work and was demonstrated as a flexible system that can be applied to a wide range of heat of absorption while still maintaining remarkable energy performance.