CO2 desorption from rich alkanolamine solution by using membrane vacuum regeneration technology

Abstract

Aiming to achieve lower regeneration energy consumption and less absorbent loss, membrane vacuum regeneration technology was developed as the novel regeneration technology for CO2 enrichment in the chemical absorption process. In this study, monoethanolamine (MEA) was selected as absorbent and polypropylene (PP) hollow fiber membrane contactors were used to test the regeneration performance. Two different operating modes, solution flowing in tube side (mode A) and in shell side (mode B) of membrane module were compared by investigating mass transfer individual resistances and the influences of key operating parameters on CO2 desorption flux for both modes. The experimental results showed that mode A was superior to mode B, and liquid side resistance was dominant in overall mass transfer resistance for both modes when membrane was gas-filled. By optimizing the operating condition, better regeneration performance could be achieved to CO2 desorption flux 2.2×10−4mol/m2s and lower total equivalent work compared to thermal regeneration. In addition, amine loss problem, MEA concentration variation after regeneration and pressure drop on liquid side were also discussed, it showed MEA loss could be limited at 0.5g MEA/kg CO2 in Mode A. However, after the long-term running of membrane vacuum regeneration, it was also supposed that risk of membrane wetting will be increased due to the increase of membrane pore size.