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Thermogravimetric study and modeling for the drying of a Chinese lignite
Author(s) -
Tahmasebi Arash,
Yu Jianglong,
Han Yanna,
Zhao Huan,
Bhattacharya Sankar
Publication year - 2013
Publication title -
asia‐pacific journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.348
H-Index - 35
eISSN - 1932-2143
pISSN - 1932-2135
DOI - 10.1002/apj.1722
Subject(s) - thermogravimetric analysis , thermodynamics , activation energy , coal , chemistry , diffusion , arrhenius equation , moisture , evaporation , water content , materials science , geotechnical engineering , physics , organic chemistry , engineering
ABSTRACT Study of drying characteristics and kinetics of coal is necessary in order to optimize drying operation and design a dryer in industrial scale. Drying characteristics of Chinese lignite was investigated experimentally using thermogravimetric method, and the effect of drying variables on drying rate was systematically studied. For CFD modeling and scale‐up purposes, it is useful to have an algebraic equation that describes the drying process of lignite. Therefore, different thin layer drying models given in the literature were employed to analyze coal drying kinetics under different conditions. During studying the consistency of all the models, statistical tests such as χ 2 , residual sum of squares ( RSS ), F ‐value, and the coefficient of determination R 2 were employed. It was found that the Midilli–Kucuk model best describes the drying process within 99.9% accuracy. The effects of drying temperature and coal sample weight on the constants and coefficients of the selected model were also studied by multiple regression analysis. Apparent diffusion coefficient of moisture from sample was calculated using the experimental kinetics data. Higher drying temperatures and smaller sample weights resulted in higher diffusion coefficient, which was consistent with experimental data. Activation energy of moisture evaporation calculated from Arrhenius equation for drying process was 21.17 kJ/mol. The selected algebraic drying model can be used for CFD modeling during scale‐up of drying facility for industrial applications. © 2013 Curtin University of Technology and John Wiley & Sons, Ltd.