Dynamic modelling of the reactive absorption of CO₂ in ionic liquids and its effect on the mass transfer and fluid viscosity

A suitable fluid dynamic model of a CO₂ absorption system using ionic liquids as solvent was studied emphasizing the impact of the viscosity of the solvent on the reactor designing issues, e.g., overall removal capacity, reactor geometry, and power required. To establish the main mass transfer and hydrodynamic parameters and in particular the impact of the viscosity in the system, a two-dimensional computational fluid dynamic (CFD) simulation was carried out to model a simple gas absorption bubble column with one inlet gas feed. To model the interface tracking, the level set method was used. The laminar and non stationary hypothesis was applied for the liquid and gas phases. The CFD software COMSOL 4.2, which employs the finite elements method to discretized the Navier Stokes and Mass Transfer fluid flow Equations, was used to simulate and analyze the obtained results from simulations. The results showed an increase of the overall mean viscosity over the time due to the CO₂ diffusion in the liquid. Meanwhile, the spatial distribution of the viscosity was very homogeneous due to the high mixing capacity of the bubble column. However, there was a slight gradient in the bottom of the reactor. This is an abstract of a paper presented at the CHISA 2012 - 20th International Congress of Chemical and Process Engineering and PRES 2012 - 15th Conference on Process Integration, Modelling and Optimisation for Energy Saving and Pollution Reduction (Prague, Czech Republic 8/25-29/2012).