Effects of water condensation on hollow fiber membrane contactor performance for CO2 capture by absorption into a chemical solvent

The present study investigates the impact of water vapor condensation on the performance of hollow fiber membrane contactors for CO2 capture by absorption into a chemical solvent. A one-dimensional adiabatic transfer model for CO2 absorption in Monoethanolamine (MEA) has been implemented in a commercial simulation environment and condensation experiments have been performed in a laboratory scale membrane contactor module. The results from these experiments show that water vapor condensation occurs in the gas phase or at the gas-membrane surface inside the fiber lumen, but not in the membrane pores. This condensation had no effect on the carbon capture efficiency, but did lead to an increase of the gas-side pressure drop and to liquid water at the gas outlet. Using simulations permitted us to better understand why condensation occurs in the fiber lumen. Indeed, it is the combined conditions of rapid heat-transfer within the membrane and relatively slow mass transfer that lead to vapor oversaturation in the gas phase promoting condensation. In industrial conditions for membrane contactor applications where water condensation is most likely to occur, membrane wetting due to condensation may thus not happen, which is an encouraging result for the membrane technology.