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Study on the Regeneration of Basic Aluminum Sulfate SO2-Rich Solution by Vacuum Desorption

Chen, Min, Deng, Xianhe, He, Feiqiang
Energy & Fuels 2016 v.30 no.10 pp. 8469-8478
absorption, aluminum sulfate, byproducts, desorption, energy, flue gas, flue gas desulfurization, oxidation, recycling, sulfites, sulfur dioxide, temperature
Basic aluminum sulfate (BAS) wet flue gas desulfurization (FGD) is a promising renewable process used to remove sulfur dioxide (SO₂) from flue gas, in which the regeneration of BAS SO₂-loaded solution is of great importance for the reuse of BAS solution. In this paper, a novel regeneration method by vacuum desorption was developed to achieve superior regeneration performance for a BAS-rich solution. The operating parameter effect on SO₂ desorption performance was thoroughly investigated in a lab-scale reactor. The experimental results demonstrated that the great decrease of pressure could significantly improve the regeneration performance, and high desorption temperature was favorable for SO₂ desorption. Furthermore, it is worth determining the optimum components of a BAS-rich solution and initial sulfite concentration, considering the contradiction between the SO₂ absorption performance and the regeneration performance. The increase of stirring speed in the liquid had a considerable positive effect on SO₂ desorption efficiency. In addition, through a simple comparison with direct heating regeneration, it indicates that the utilization of vacuum regeneration could have the potential to improve the regeneration rate and lower the total energy consumption. Finally, the recycling experiments of the absorption–desorption process show that the BAS solution could be reused successfully to capture SO₂ from flue gas by vacuum regeneration, while SO₂ absorption efficiency would decrease to below 90% after 11 cycles, attributed to the inevitable oxidation of byproduct in the desulfurization process.