Studies on magnesium-based wet flue gas desulfurization process with oxidation inhibition of the byproduct

► A systematical study on a novel magnesium-based WFGD process with a spray scrubber. ► Na2S2O3 was found effectively to inhibit the oxidation of desulfurization byproduct. ► The desulfurization efficiency could reach a high level above 90%. ► A desulfurization process model was established by the double-film theory. ► The desulfurization process was found to be controlled by gas-film diffusion. This paper presents a novel magnesium-based wet flue gas desulfurization (FGD) process in which sodium thiosulfate is used to inhibit the oxidation of desulfurization byproduct. Effects of different operating variables in FGD process were experimentally researched in a spray scrubber. The results showed that the magnesium-based wet FGD process was more suitable for low SO2 concentration flue gas and indicated that the adding of Na2S2O3 could slightly enhance the desulfurization process and the MgSO3 content in the byproduct could be maintained above 95% when the thiosulfate-sulfite ratio was controlled above 1:6. A desulfurization process model was established by the double-film theory of mass transfer. The calculated mass transfer coefficients were in reasonable agreement with the experimental values and the absorption process was found to be controlled by gas-film diffusion.