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Study on the formation of micro glass-beads during staged combustion Zhiqiang Wang, Dakai Wang, Pan Ji, and Xingxing Cheng Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/acs.energyfuels.8b01134 • Publication Date (Web): 03 Jul 2018 Downloaded from http://pubs.acs.org on July 10, 2018
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Energy & Fuels
Study on the formation of micro glass beads during staged combustion Zhiqiang Wang, Dakai Wang, Pan Ji, Xingxing Cheng* School of Energy and Power Engineering; Shandong University, Jinan, Shandong Province, China. *
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Key words: micro glass beads; temperature; staged combustion Abstract: The effect of ambient temperature on the formation of microscopic (micro) glass beads was studied, using a drop tube furnace in a weak reducing atmosphere, under conditions of controlled (staged) combustion. Indonesian coal, which has a high ash content, was used, and the experimental temperatures ranged from 1300 °C to 1500 °C. The fly ash was analyzed by an X-ray diffractometer and a scanning electron microscope, and the yield of cenospheres with density lower than 1 g/m3 was determined by wet separation. The experimental results showed that the content of quartz in the fly ash decreased with increase in experimental temperature, while the content of the glass phase barely changed. The particles gradually assumed a spherical shape, with an average aerodynamic diameter of approximately 7 µm. The proportion of cenospheres with density less than 1 g/m3 gradually increased with increasing temperature. Based on the above analysis, it can be qualitatively concluded that increased ambient temperature promotes the formation of micro glass beads.
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Energy & Fuels
1. Introduction With the continuous development of the social economy, demand for electricity in various fields has gradually increased. In current global energy consumption, coal occupies a very important role 1-4, however, coal-fired power plants generate large quantities of fly ash 4-5 each year, which puts tremendous pressure on environmental protection in various countries. According to its micromorphology and internal structure, fly ash is mainly composed of glass beads, sponge-like irregular porous bodies, and a small amount of unburned carbon particles 1, 3. Glass beads collected from flue gas are a widely-used industrial byproduct 2, 6-8, due to their excellent physical and chemical properties. Flue gas glass beads have a wide range of aerodynamic diameters, from 0.1-100 µm. At present, most coal-fired power plants remove fly ash particles with a particle size in the aerodynamic diameter range of 0.1-2.5 µm, with filtration efficiency 85%-99% 9-10. Examining the tail flue of some coal-fired power plants, it was found that some small-radius glass beads (PM
