CFD Prediction with Eulerian/Eulerian Approach of SO2 Absorption from Flue Gases in Bubble-Dispersion Tower

Accurate prediction of SO2 absorption efficiency under different physical and chemical parameters is of significant importance for desulfurization of the flue gas. In order to understand the mechanism of SO2 absorption inside a bubble-dispersion tower, a three-dimensional twin Eulerian model together with two-film theory was applied to simulate the flue gas desulfurization processes in a bubble-dispersion tower. After comparing the predicted desulfurization efficiencies by using calculated gas holdup with the experimental parameters, the deviation of simulated model with the measured ones was small. Moreover, it was observed that the larger the fractional hole area, the better desulfurization performance. The bubble tower showed fine adaptability when the superficial gas velocity varies from 0.3 to 0.7 m/s. Also, there was a positive correlation between the SO2 removal ability and the hydrogen ion concentration. Considering the crystallization of calcium sulfite, the PH of slurry tank inside bubble tower is recommended to be set between 5.5 and 6, and the initial CaCO3 mass fraction is suggested to be set around 10–15% under prediction conditions. Moreover, the SO2 absorption capability could be increased by lifting the initial liquid height, while the SO2 removal efficiency would level off when tube insertion depth/column diameter H/D was over 0.128, so the H/D is suggested to be set from 0.08 to 0.128 to achieve high SO2 absorption and avoid soil erosion. It was observed that the smaller the size of bubbles generated in the slurry, the higher SO2 absorption efficiency could be.