Modification of rich-split carbon capture process using ceramic membrane for reducing the reboiler duty: Effect of membrane arrangements

Abstract

In order to reduce the reboiler duty, the conventional CO2 chemical absorption process had been retrofitted by splitting some cold CO2-rich solvent prior to the lean-rich heat exchanger to recover the latent heat of hot stripped gas vented from CO2 desorber, which was called the rich-split carbon capture process. In this study, we promoted this rich-split carbon capture process by introducing 4 nm pore size tubular ceramic membranes, in which the coupled heat and water transfers from the stripped gas into the split CO2-rich monoethanolamine (MEA) aqueous solution across the membrane were permitted. Five types of ceramic membrane arrangements (Mode A to Mode E) were experimentally investigated and compared at different operating conditions in terms of the heat flux per volume of ceramic membrane (QCM). Results showed that among all the five ceramic membrane arrangements, the best heat recovery performance in terms of QCM value can be achieved using Mode-A where the stripped gas and rich MEA solvent flows were serially arranged in two serial ceramic membranes. Additionally, Mode-A has the best operating flexibility to the changes of water vapor content and stripped gas flow rate. Our study demonstrated that Mode-A may be an excellent candidate for recovering more waste heat at a high stripped gas flow rate. Furthermore, Mode-E can obtain a comparable heat recovery performance to Mode-A. In Mode-E, four parallel ceramic membrane tubes were bundled to form a heat exchanger with the same membrane volume to Mode-A. So if the layout of membrane tubes and shell size in Mode-E can be optimized elaborately, Mode-E will show a competitiveness in making the heat exchanger more compact on the premise of high heat recovery performance.