Thermogravimetric study and modeling for the drying of a Chinese lignite

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 χ2, residual sum of squares (RSS), F-value, and the coefficient of determination R2 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.

[1]  W. K. Lewis.  The Rate of Drying of Solid Materials. , 1921 .

[2]  G. E. Page,et al.  FACTORS INFLUENCING THE MAXIMUM RATES OF AIR DRYING SHELLED CORN IN THIN LAYERS. , 1949 .

[3]  J. R. O'Callaghan,et al.  Digital simulation of agricultural drier performance , 1971 .

[4]  W. L. Harris,et al.  Energy Characteristics of an Impinged Flame , 1973 .

[5]  G. M. White,et al.  Relative Humidity Effect on the High-Temperature Drying of Shelled Corn , 1973 .

[6]  G. M. White,et al.  Fully-Exposed Drying of Popcorn , 1981 .

[7]  Ray A. Bucklin,et al.  Effects of Drying Air Parameters on Rice Drying Models , 1985 .

[8]  Drying characteristics of Morwell brown coal and effects of drying on liquefaction , 1986 .

[9]  R. Abhari,et al.  Drying kinetics of lignite, subbituminous coals, and high-volatile bituminous coals , 1990 .

[10]  Qin Zhang,et al.  AN OPTIMIZATION OF INTERMITTENT CORN DRYING IN A LABORATORY SCALE THIN LAYER DRYER , 1991 .

[11]  Digvir S. Jayas,et al.  REVIEW OF THIN-LAYER DRYING AND WETTING EQUATIONS , 1991 .

[12]  K. Vorres,et al.  Drying of Beulah-Zap lignite☆ , 1992 .

[13]  K. Vorres.  Effect of temperature, sample size and gas flow rate on drying of Beulah-Zap lignite and Wyodak subbituminous coal , 1994 .

[14]  D. Walsh,et al.  Overview of Low-Rank Coal (LRC) Drying , 1997 .

[15]  A. Ayensu,et al.  Dehydration of food crops using a solar dryer with convective heat flow , 1997 .

[16]  Guohua Chen,et al.  Heat and mass transfer in fixed-bed drying , 1999 .

[17]  P. Agarwal,et al.  Steam-drying of coal. Part 1. Modeling the behavior of a single particle , 2000 .

[18]  Osman Yaldýz,et al.  THIN LAYER SOLAR DRYING OF SOME VEGETABLES , 2001 .

[19]  B. K. Bala,et al.  THIN-LAYER DRYING CHARACTERISTICS FOR GREEN CHILLI , 2002 .

[20]  A. Midilli,et al.  A NEW MODEL FOR SINGLE-LAYER DRYING , 2002 .

[21]  A. Midilli,et al.  Mathematical modeling of thin layer drying of pistachio by using solar energy , 2003 .

[22]  Dursun Pehlivan,et al.  Modelling of drying kinetics of single apricot , 2003 .

[23]  Turan Çalban,et al.  Drying of a Turkish Lignite in a Batch Fluidized Bed , 2003 .

[24]  Nenad Sarunac,et al.  USE OF COAL DRYING TO REDUCE WATER CONSUMED IN PULVERIZED COAL POWER PLANTS , 2004 .

[25]  S. Babalis,et al.  Influence of the drying conditions on the drying constants and moisture diffusivity during the thin-layer drying of figs , 2004 .

[26]  Adnan Topuz,et al.  An experimental and numerical study of fluidized bed drying of hazelnuts , 2004 .

[27]  Arif Hepbasli,et al.  Mathematical modelling of drying of bay leaves , 2005 .

[28]  K. Saçılık,et al.  Drying kinetics of Üryani plum in a convective hot-air dryer , 2006 .

[29]  K. Saçılık,et al.  Mathematical modelling of solar tunnel drying of thin layer organic tomato , 2006 .

[30]  Haihui Wang.  Kinetic Analysis of Dehydration of a Bituminous Coal Using the TGA Technique , 2007 .

[31]  A. Sander.  Thin-layer drying of porous materials: Selection of the appropriate mathematical model and relationships between thin-layer models parameters , 2007 .

[32]  İlhan Ceylan,et al.  Mathematical modeling of drying characteristics of tropical fruits , 2007 .

[33]  L. Diamante,et al.  Mathematical modelling of hot air drying of sweet potato slices , 2007 .

[34]  F. López-Rodríguez,et al.  Mathematical modelling of thin-layer infrared drying of wet olive husk , 2008 .

[35]  İbrahim Doymaz,et al.  Convective drying kinetics of strawberry , 2008 .

[36]  Junmeng Cai,et al.  Determination of Drying Kinetics for Biomass by Thermogravimetric Analysis under Nonisothermal Condition , 2008 .

[37]  S. Soponronnarit,et al.  Models of fluidized bed drying for thin-layer chopped coconut , 2009 .

[38]  Jianglong Yu,et al.  Experimental study on drying and moisture re-adsorption kinetics of an Indonesian low rank coal. , 2009, Journal of environmental sciences.

[39]  Wen Liu,et al.  The Potential of Renewable Energy Systems in China , 2009 .

[40]  Matthias Schreiber,et al.  Drying of Lignite in a Pressurized Steam Fluidized Bed—Theory and Experiments , 2009 .

[41]  A. Mujumdar,et al.  Low-Rank Coal Drying Technologies—Current Status and New Developments , 2009 .

[42]  Jianglong Yu,et al.  Pyrolysis and Combustion Characteristics of an Indonesian Low-Rank Coal under O2/N2 and O2/CO2 Conditions† , 2010 .

[43]  Xiaohong Zhang,et al.  Thin-layer drying kinetics and quality changes of sweet sorghum stalk for ethanol production as affected by drying temperature , 2011 .

[44]  S. Meziane,et al.  Drying kinetics of olive pomace in a fluidized bed dryer , 2011 .

[45]  Yasuki Kansha,et al.  Self-heat recuperative fluidized bed drying of brown coal , 2011 .

[46]  Arash Tahmasebi,et al.  A study of chemical structure changes of Chinese lignite during fluidized-bed drying in nitrogen and air , 2012 .

[47]  Arash Tahmasebi,et al.  Study of Chemical Structure Changes of Chinese Lignite upon Drying in Superheated Steam, Microwave, and Hot Air , 2012 .

[48]  Wei‐Cheng Wang,et al.  Laboratory investigation of drying process of Illinois coals , 2012 .

[49]  Arash Tahmasebi,et al.  A review on water in low rank coals: The existence, interaction with coal structure and effects on coal utilization , 2013 .