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Selection of Desulfurizer and Control of Reaction Products on Flue-Gas Desulfurization Using Chemical-Looping Technology

Xuan, Yanni, Yu, Qingbo, Qin, Qin, Wang, Kun, Duan, Wenjun, Liu, Kaijie, Zhang, Peng
Energy & fuels 2018 v.32 no.1 pp. 889-900
Gibbs free energy, air, byproducts, carbon dioxide, computer software, economic valuation, energy efficiency, flue gas, flue gas desulfurization, fuels, hydrogen, manganese oxides, nitrogen oxides, oxygen, pollution, sulfur, sulfur dioxide, temperature
Chemical-looping technology (CLT) can achieve energy efficiency and reduce the environmental pollution and is usually conducted on a fixed-bed reactor. In this paper, the thermodynamic simulations for flue-gas desulfurization (FGD) systems with CLT are carried out using HSC Chemistry software to choose a suitable desulfurizer, control the type and quantities of reaction products, and collect sulfur-containing byproducts with high economic value. The Ellingham diagrams are developed to relate the Gibbs free energy of the relevant reactions to the temperature. The fixing-sulfur potential; the reaction degree with CO₂, H₂O, and CO; and the acceleration effect of removing NOₓ of different metal oxides in 100 to 300 °C are estimated. Compared comprehensively, Mn-based oxides have distinct advantages for flue-gas desulfurization using CLT. Based on calculation results, both low reaction temperatures (T < 400 °C) and sufficient H₂ (mH₂/mMₙSO₄ > 4) can effectively prevent the loss of sulfur element. In the regeneration of Mn₃O₄, if pure O₂ is replaced by diluent air or a low level of oxygen, the formation of trace amounts of MnSO₄ can be inhibited. This paper provides ample theoretical basis for Mn-based oxides as active components of desulfurizer and collecting pure SO₂ from flue gas through chemical-looping technology.