Evaluation of Solvent Degradation in Amine-Based Post-Combustion Capture Process Simulations.

Abstract

It is important to limit solvent degradation in amine-based post combustion capture systems, as it can lead to challenges, such as solvent losses, reductions in process performance, increased emissions, and corrosion of process equipment. In this work a degradation model is developed for oxidative and thermal degradation of monoethanolamine (MEA) based on experimental data and models from literature. The degradation model is then used to evaluate degradation in a typical coal fired post-combustion capture plant and investigate the effects of process design decisions on the degradation. The total degradation in the plant is predicted to be 0.064 kg MEA/ton CO2, of which around 80% is caused by oxidative degradation. Degradation in the structured packing of the absorber accounts for 56% of the oxidative degradation as a result of increased temperatures due to CO2 absorption. A single intercooler stage in the absorber can nearly halve oxidative degradation in the packing but has limited impact on degradation in the sump and heat exchanger, which is caused by dissolved O2. The overall degradation is reduced 19% in comparison to the base case process. Additional intercooling has the potential to reduce the overall degradation by 33%. Higher O2 concentrations in the flue gas are found to lead to more oxidative degradation in the absorber packing and sump as well as in the heat exchanger, where the effect is most significant.