Experimental study on reactivity and inorganic component transformation of activated fuels in a fluidized bed

doi:10.1016/j.cjche.2024.06.013

Abstract

Abstract: The gasification and combustion of activated fuels produced from fluidized beds are beneficial for achieving clean and efficient coal utilization. In this study, a high-calcium coal was used for the activation process, carried out in a high-temperature vertical fluidized bed. The carbon and ash characteristics of activated fuels were studied. The reactivity of activated fuels was characterized using Raman test, and scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS). Inorganic components were characterized using X-ray diffraction (XRD) and X-ray fluorescence spectrometry (XRF). With the increase in temperature and equivalence ratio (ER), the graphitization degree of activated fuels decreases, and a higher proportion of active sites leads to, a better activation effect. The activation effect is optimized at the equivalence ratio of 0.45. As the temperature rises, the calcium-containing minerals in the raw coal are gradually transformed into anorthite (CaAl₂SiO₇), and the anhydrite (CaSO₄) reacts with the reducing gas (CO) to produce oldhamite (CaS); Fe₂O₃, as a fluxing agent, is prone to melting with silica-aluminates at high temperature. As the particle size of activated fuel increased, the relative enrichment index (REI) of heavy metals decreased.

Key words: Activation, Fluidized-bed, Microstructure, Ash characteristics, Mineral transformation, Ash fusion

摘要： The gasification and combustion of activated fuels produced from fluidized beds are beneficial for achieving clean and efficient coal utilization. In this study, a high-calcium coal was used for the activation process, carried out in a high-temperature vertical fluidized bed. The carbon and ash characteristics of activated fuels were studied. The reactivity of activated fuels was characterized using Raman test, and scanning electron microscopy coupled with energy-dispersive spectrometry (SEM-EDS). Inorganic components were characterized using X-ray diffraction (XRD) and X-ray fluorescence spectrometry (XRF). With the increase in temperature and equivalence ratio (ER), the graphitization degree of activated fuels decreases, and a higher proportion of active sites leads to, a better activation effect. The activation effect is optimized at the equivalence ratio of 0.45. As the temperature rises, the calcium-containing minerals in the raw coal are gradually transformed into anorthite (CaAl₂SiO₇), and the anhydrite (CaSO₄) reacts with the reducing gas (CO) to produce oldhamite (CaS); Fe₂O₃, as a fluxing agent, is prone to melting with silica-aluminates at high temperature. As the particle size of activated fuel increased, the relative enrichment index (REI) of heavy metals decreased.

关键词: Activation, Fluidized-bed, Microstructure, Ash characteristics, Mineral transformation, Ash fusion

Yujie Hu, Wei Li, Rui Chen, Chi Zhang, Shaobo Han, Ruifang Cui, Jiangong Lin, Qiangqiang Ren. Experimental study on reactivity and inorganic component transformation of activated fuels in a fluidized bed[J]. Chinese Journal of Chemical Engineering, 2024, 74(10): 52-62.

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