Influence of ash composition on the sintering behavior during pressurized combustion and gasification process

• Published in: Journal of Zhejiang University. A. Science Vol. 13; no. 3; pp. 230 - 238
• Main Authors: Jing, Ni-jie, Wang, Qin-hui, Yang, Yu-kun, Cheng, Le-ming, Luo, Zhong-yang, Cen, Ke-fa
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Zhejiang University Press 01.03.2012
• Subjects: Ashes; Civil Engineering; Classical and Continuum Physics; Combustion; Engineering; Eutectics; Gasification; Industrial Chemistry/Chemical Engineering; Mechanical Engineering; Minerals; Scanning electron microscopy; Sintering; X-ray diffraction; Sintering temperature; Field emission scanning electron microscope/energy dispersive X-ray spectrometer (FE-SEM/EDS); Ash composition; TQ533; X-ray diffractometer (XRD)
• ISSN: 1673-565X; 1862-1775
• DOI: 10.1631/jzus.A1100206

To determine the ash characteristics during fluidized bed combustion and gasification purposes, the investigation of the impacts of chemical composition of Jincheng coal ash on the sintering temperature was conducted. A series of experiments on the sintering behavior at 0.5 MPa was performed using the pressurized pressure-drop technique in the combustion and gasification atmospheres. Meanwhile, the mineral transformations of sintered ash pellets were observed using X-ray diffractometer （XRD） analyzer to better understand the experimental results. In addition, quantitative XRD and field emission scanning electron microscope/energy dispersive X-ray spectrometer （FE-SEM/EDS） analyses of ash samples were used for clarifying the detailed ash melting mechanism. These results show that the addition of Fe203 can obviously reduce the sintering temperatures under gasification atmospheres, and only affect a little the sintering temperature under combustion atmosphere. This may be due to the presence of iron-bearing minerals, which will react with other ash compositions to produce low-melting-point eutectics. The FE-SEM/EDS analyses of ash samples with Fe203 additive show consistent results with the XRD measurements. The CaO and Na20 can reduce the sintering temperatures under both the combustion and gasification atmospheres. This can be also contributed to the formation of low-melting-point eutectics, decreasing the sintering temperature. Moreover, the fluxing minerals, such as magnetite, anhydrite, muscovite, albite and nepheline, contribute mostly to the reduction of the sintering temperature while the feldspar minerals, such as anorthite, gehlenite and sanidine, can react with other minerals to produce low-melting-point eutectics, and thereby reduce the sintering temperatures.