Characteristic analysis and drying kinetics of “high carbon and high moisture” coal gasification fine slag
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Abstract
“High carbon and high moisture” coal gasification fine slag has a high fixed carbon content and dry based high calorific value. However, due to its high moisture content of about 70%, it leads to low received base low calorific value, seriously affecting its further comprehensive utilization. The ash content of the gasification fine slag sample in Ningxia coal-water slurry furnace is 50.04%, and the dry based high calorific value reaches 3 809 cal/g, which has high utilization value. However, the moisture content of the gasification fine slag filter cake is as high as 69.2%, and the received base low calorific value is only 790 cal/g. Further reducing the moisture content of the filter cake is the key to effectively improving its comprehensive utilization efficiency. The fine slag contains minerals such as SiO2, Fe2O3, CaSi2, etc. The microstructure is mainly composed of flocculent structure, independent spherical particles, and flocculent spherical mixed structure. The elements on the surface of the flocculent structure are mainly C and O, while the elements on the surface of the spherical particles are mainly O, C, and Fe. At the same time, the morphology observation shows that the pores of the coal gasification fine slag are developed and dehydration is difficult. Drying and dehydration experiments are conducted on fine slag filter cake samples, and the drying rate shows a trend of increasing first and then gradually decreasing at different drying temperatures. In the drying kinetics model, the semi empirical model can more accurately describe the drying and dehydration characteristics of the coal gasification fine slag compared to the semi theoretical model. Among them, the Page model has the most prominent fitting effect and the simplest form, fitting the drying and dehydration kinetics equation.
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