Megalopolis lignite drying kinetics based on TGA experimental results

Abstract

Lignite drying kinetic data are of critical importance for the design of drying and occasionally gasification process equipment because of the particularly high (55–60%) moisture content held in the lignite particles. A lumped kinetic model, R d( t) = η k d( T)( W * - W( t)) n d( T) , describing the dependence of the drying rate upon the residual moisture content (dry basis) of lignite single-particle systems is proposed in this paper. The mathematical analysis is based on data obtained from TGA experimental studies carried out on lumps or on samples of pulverized Greek (Megalopolis) lignite in a nitrogen atmosphere under transient temperature conditions. (A rate of temperature rise 20°C/min, up to 100°C, was applied.) The temperature dependence of both the relevant rate constant and the kinetic order was determined by the best fit of the theoretical model to the relevant experimental data. Megalopolis lignite drying can be described satisfactorily by the kinetic equation ▪ η = f( d p) and T = f′( t) are described graphically in the text.