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Removal of SO2 from Flue Gas Using Basic Aluminum Sulfate Solution with the Byproduct Oxidation Inhibition by Ethylene Glycol

Chen, Min, Deng, Xianhe, He, Feiqiang
Energy & Fuels 2016 v.30 no.2 pp. 1183-1191
absorption, aluminum, aluminum sulfate, byproducts, desorption, ethylene glycol, flue gas, flue gas desulfurization, mass transfer, models, oxidation, pH, sulfites, sulfur dioxide, temperature
This paper presents a novel wet flue gas desulfurization (FGD) technology based on a basic aluminum sulfate (BAS) desorption regeneration process, in which ethylene glycol (EG) was first employed to inhibit the byproduct oxidation. The operating parameter effect on SO₂ absorption efficiency and oxidation efficiency of sulfite was thoroughly examined in a lab-scale bubbling column. The results indicated that both the amount of aluminum and basicity play important roles on the desulfurization time with above 90% absorption efficiency. The BAS-based desulfurization process was more suitable for a low temperature and low gas flow rate. High inlet SO₂ concentrations may contribute to the mass-transfer rate of SO₂, and the SO₂ absorption efficiency remained above 90% when the pH value was over 3.10. With the addition of 1% (v/v) EG in BAS solution, the oxidation efficiency dropped dramatically from 86 to below 10% (in 120 min). On the basis of the two-film theory, a model of the SO₂ absorption process was developed and the mass-transfer characteristics were analyzed. The calculation results indicated that the SO₂ absorption process for this system was decided by a combination of both the gas- and liquid-phase diffusion controls.