Studying a baffled hollow fibre membrane contactor for carbon dioxide capture

Gas absorption membrane (GAM) systems are a promising alternative technology for CO2 capture from flue gas. Even though a great deal of effort has been put into membrane contactor studies for CO2 absorption applications, knowledge of membrane module design for industrial applications is still limited. Baffled contactors are gaining more attention from researchers because they overcome the shortcomings of parallel flow systems. Previous research has reported the positive effects of baffles in mass transfer devices, especially air stripping processes and distillation systems. However, the knowledge for applying baffles in membrane modules for CO2 absorption is still inadequate and unclear.;In this thesis, a novel GAM contactor design with cross-flow characteristics was proposed. Within the design, baffles were installed on the shell side of the membrane module for the purpose of optimizing flow orientation. The fundamental design of the membrane contactor in this study was based on a successful GAM system previously tested at the International Test Centre for CO2 Capture (ITC), University of Regina. The design of the baffled system was based on optimal designs for shell-and-tube heat exchangers. The effects of the baffles on module performance were investigated under different operating conditions in comparison with an unbaffled module. Experimental results showed that the CO2 absorption performance can be improved by integrating baffles into the hollow fibre membrane module. Under a variety of operating conditions, the baffled GAM system produced larger CO2 flux than the unbaffled system. Baffles can reasonably increase the flux in a CO2 capture process by (1) improving the gas flow by converting the flow pattern into cross-flow, thus alleviating the negative influence of heterogeneous flow and dead-zones, and (2) increasing shell-side fluid velocity and hence the mass transfer coefficient. The enhancement of the absorption performance due to the use of baffles was confirmed by the increase in the overall gas phase mass transfer coefficient, KG.