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Influencing Mechanism of Additives on Ash Fusion Behaviors of Straw

Li, Fenghai, Fan, Hongli, Guo, Mingxi, Guo, Qianqian, Fang, Yitian
Energy & fuels 2018 v.32 no.3 pp. 3272-3280
X-ray diffraction, additives, atomic absorption spectrometry, corn stover, deformation, dolomite, fuels, kaolinite, magnesium oxide, melting point, network theory, rice, silica, silicon, temperature, wheat straw
Ash fusion characteristics of straws [wheat straw (WS), corn stalk (CS), and rice stalk (RS)] and the effects of additives (kaolinite and dolomite) on their fusion behaviors under a reducing atmosphere were explored using an inductively coupled plasma atomic emission spectrometry, X-ray diffractometer (XRD), network theory, and Factsage calculation. The results shows that kaolinite and dolomite can promote the ash fusion temperatures (AFTs) of three straws, respectively. For three straw ashes, kaolinite makes their deformation temperatures (DTs) obviously increase, while dolomite results in obvious increases in their flow temperatures (FTs). The DT is closely related to the contents of low melting point (MP) minerals and amorphous matter, and the FT is mostly determined by the skeleton structure of high MP mineral. Dolomite addition makes three straw AFTs increase through the formations of high MP lime, magnesia, and merwinte, while SiO₂ from kaolinite decomposition might lead to the generation of low MP mineral forsterite, kirschstenite, and amorphous matter, especially for WS and CS with low silicon content. High MP kaliophilite formation causes an AFT increase of the mixture of straw and kaolinite. The combination of XRD, network theory, and FactSage calculation provides a good method to explore the AFT variation mechanism of straw ashes from mineral evolution.