Experimental and Modeling Study of Trace CO2Removal in a Hollow-Fiber Membrane Contactor, Using CO2-Loaded Monoethanolamine

Trace carbon dioxide (CO 2 ) removal from an enclosed space was studied experimentally and theoretically in a hollow-fiber membrane contactor using monoethanolamine (MEA) solution. Changes in trace CO 2 removal performance with liquid flow rate, gas flow rate, absorption temperature, and CO 2 loading were investigated individually in an apparatus under well-defined and controlled experimental conditions. We developed a two-dimensional (2-D) mathematical model to predict and further analyze the experimental results. The modeling results agreed well with the experimental work. Liquid flow rate positively influences trace CO 2 removal, but is not recommended for operation at a very high level. Increasing the gas flow rate improves CO 2 absorption flux at the cost of reducing CO 2 removal efficiency; the optimal gas flow rate for the trade-off between CO 2 removal efficiency and absorption flux is presented. The optimal absorption temperatures change with liquid CO 2 loading for trace CO 2 removal. CO 2 removal efficiency is a decreasing function of CO 2 loading; the recommended CO 2 loading of MEA solution is below 0.35 mol CO 2 /mol MEA. To predict the influence of membrane wetting on trace CO 2 removal, we also propose a model that incorporates membrane wetting. The minimum breakthrough pressure are 0.38 and 0.0581 MPa for fresh membrane and old membrane, respectively. Membrane wetting significantly deteriorates trace CO 2 membrane absorption performance, with CO 2 removal efficiency decreasing suddenly once the membrane is wetted.