(373ab) Dynamic Modeling and Simulation of a Membrane Contactor for CO2 Absorption

It’s known that in recent decades researchers have paid attention on the trial to reduce CO₂ emissions into the atmosphere, which has led to the development of technologies with the ability of removing the pollutant from gaseous streams. These technologies are commonly called CCS (Carbon Capture and Storage) technologies. Many methods for carbon capture were studied and optimized, although the conventional ones still present some disadvantages, such as the separation on absorption column methods. Therefore, as the membrane separation methods provide some advantages if compared to many others, this manuscript presents an approach for the modeling of CO₂ absorption carried out on a hollow fiber membrane contactor (HFMC) using an aqueous monoethanolamine solution as the solvent. The model consists on partial differential molar balances for the gas and liquid phases, so for the membrane and a global molar balance on the gas phase to give the velocity equation. Kinetics and thermal effects were not taken into account for this approach, as also the effects of pressure drop. Each concentration depends on the time and the axial coordinate, giving rise to a partial differential equations system that were discretized by the past finite difference method, which has turned it into an ordinary differential equation (ODE) system solved by an ODE solver on Python software. The geometry parameters and volumetric flow rates of the HFMC were configured to obtain a CO₂ capture ratio of 90%, so the process transient behavior could be observed under certain initial conditions. The results obtained were good and consistent with the expected behavior. The concentration of the solute on the gas phase decreases with the time and the z axis, as shown on Figure 1 (a), which means that there’s CO₂ migrating from the gas to the liquid phase, as shown on Figure 2 (b). Also the maximum mass transfer can be observed by the liquid phase behavior on time equals 161 seconds. The system achieves the steady-state in about 7000 seconds and thereafter the capture ratio remains constant.