Coupling between Mass Transfer and Chemical Reactions during the Absorption of CO2 in a NaHCO3-Na2CO3 Brine : Experimental and Theoretical Study

This work deals with the study of the gas-liquid mass transfer, coupled with chemical reactions. The case of carbonic gas absorption in a brine of sodium carbonate and bicarbonate is investigated. It is performed in collaboration with Solvay SA. The aim of this work is to get a better understanding of this phenomenon. It would permit an optimization of the refined sodium bicarbonate production process. The basis of developed mathematical models is presented. The CO2 absorption is coupled with several chemical reactions taking place in the liquid phase. A mathematical modelling of this coupling is first developed. The equations of the model are solved numerically, using COMSOL Multiphysics. To model the bubble-liquid mass transfer of CO2, this diffusion-reaction model is completed by a representation of the liquid phase flow around the bubble. In order to validate experimentally each scale of modelling, two experimental devices are proposed.