School of Chemical and Minerals Engineering, Potchefstroom Campus, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa; Department of Chemical Engineering Technology, University of Johannesburg, P.O. Box 17011, Doornfontein, 2082, South Africa
Everson, R.C., School of Chemical and Minerals Engineering, Potchefstroom Campus, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa; Neomagus, H.W.J.P., School of Chemical and Minerals Engineering, Potchefstroom Campus, North-West University, Private Bag X6001, Potchefstroom, 2520, South Africa; Njapha, D., Department of Chemical Engineering Technology, University of Johannesburg, P.O. Box 17011, Doornfontein, 2082, South Africa
A technique using non-isothermal thermogravimetric analyser results was developed for the validation of reaction rate models together with associated parameters suitable for chemically controlled gas-solid reactions. The solution of the temperature integral which occurs in the calculation is achieved by numerical integration with respect to a dimensionless activation energy variable, y=E/RT, following a transformation of the temperature integral equation. The evaluation of the validity of the kinetic model and determination of all the constants is accomplished with a two-step regression procedure with experimental results from several thermogrammes with different linear heating rates. The technique was validated by comparing results obtained for the combustion of two coal-chars with corresponding isothermal results using a shrinking core model with a nth order surface reaction. © 2005 Elsevier Ltd. All rights reserved.