Determining the Performance of an Efficient Nonaqueous CO2 Capture Process at Desorption Temperatures below 373 K

Efficient CO2 capture by chemical absorption is currently gaining interests for the control greenhouse gas emissions. In this work, a nonaqueous process was developed to regenerate CO2 below 373 K by removing methanol first after the hybrid solvent of monoethanolamine (MEA) and methanol had absorbed CO2. A model was accordingly developed to analyze the performance of the desorption process. Experiments were performed to determine the missing reaction kinetics of nonaqueous solvent regeneration of CO2 to help develop the model. The predicted gas concentration, axial velocity, energy consumption, and desorption efficiency agreed well with the stripper experimental data. A parametric analysis was conducted to investigate the effects of temperature, pressure, lean solvent loading, gas/liquid ratio, packing, and internals on the energy consumption and desorption efficiency. All analyses were performed under three defined desorption conditions: N2, methanol vapor, and steam as purge gases. Major energy savings were clearly identified because of feasible desorption temperatures below 373 K under nonaqueous desorption conditions. N2 purge gas desorption conditions offered the minimum energy consumption of 2.28 GJ/t, being 24% below the typical value of 3.0 GJ/t. Additionally, it was found that the nonaqueous environment improved the desorption efficiency by 10% compared to that obtained by typical aqueous solution regeneration.