CFD modeling and experimental study of carbon dioxide removal in a lab-scale spray dryer

In a co-current lab-scale spray dryer absorber fitted with a two-fluid nozzle, the removal of carbon dioxide through chemical absorption with NaOH solution as absorbent was investigated experimentally and theoretically. Experimental results showed that in selected ranges of operating parameters, increasing the inlet gas temperature and absorbent concentration has the increasing-decreasing effect on the overall removal efficiency. Also increasing L/G ratio (liquid to gas flow rate), decreasing inlet CO2 concentration and decreasing the droplet mean diameter had favorable effects on overall removal efficiency. Process modeling was done through Computational Fluid Dynamics (CFD) method and using Ansys Fluent 13.0 software. In the three dimensional model of the process the gas phase was modeled as a continuum using the Euler approach and the droplet/particle phase was modeled by the Lagrange approach. An empirical correlation for reaction rate was obtained through experimental data and added to the CFD model of the process as a surface reaction via a user defined function. Predictions of the CFD model were compared to the experimental data. The model prediction in comparison to the experimental trends is fair. (c) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.