Self-desulfurization reaction in oil shale fluidized beds

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In the fluidized bed combustion of oil shale, adding limestone is an effective way to reduce sulfur dioxide emissions in flue gas, and quantitatively predicting the amount of limestone required has been one of the topics studied by scientists over the years. The mineral content in oil shale is greater than 30%, and the main components of the ash produced upon combustion are SiO2, Al2O3, Fe3O4, CaO, MgO, N2O, and K2O. The ash itself can potentially remove a portion of sulfur dioxide. Gray and Antonio found through experiments that the ability of the ash to capture sulfur is related to the content of (CaO+MgO+K2O+Na2O) in the ash; the sulfur-capturing reaction involving metal oxides in the ash is governed by the relationship between △GТ and T, which is determined through calculations ； (1) The sulfur fixation reaction of CaO. Over the entire operating range of the sulfurization bed, when △GT for reaction (3) is 1150 K, △GT for reaction (4) is ≥0, indicating that the sulfur fixation reaction cannot occur. At T ≤ 1150 K, since the line corresponding to reaction (4) lies below that of reaction (3), the thermodynamic preference for sulfur fixation is MgONa2O > CaO. (4) Sulfur fixation reaction of Al2O3 and Fe3O4. Al2O3 and Fe3O4 do not possess sulfur-fixing capability during fluidized bed combustion. At T