A mathematical model to characterize volatile matter evolution during carbonisation in metallurgical coke ovens

The carbonisation mechanism in the coke oven chamber is quite complex
and, although much useful information has been generated by empirical studies on
both industrial batteries and pilot ovens, attempts to mathematically model the coke
oven phenomena met with only limited success. In this study, a mathematical model
to simulate volatile matter evolution during carbonisation process for Indian coals has
been developed. This model is a part of the endeavour to develop a rigorous
mathematical model to simulate the main physical , chemical changes and transient
heat transfer phenomena occurring during thermal decomposition of coals in coke
oven carbonisation. To have sufficient generality for the applications to coke oven
practices, the mathematical model describes the kinetics of release of main volatile
matter constituents , thereby, permitting the changes in the mass and composition of
solid residue to be estimated by element balances. The prediction of volatile matter
evolution has been made from coal ultimate analysis and heating profile based on
the principles of kinetics and rate phenomena. The aim of this mathematical model is
to predict the yield and composition of volatile matter as a function of charge
temperature and to relate these to the changes in the semi-coke composition for
some typical Indian coals used for coke making in the metallurgical coke ovens. The
quantity of volatile matter loss from coal during carbonisation was also determined
experimentally using a standard thermogravimetric analyser (TGA), in which the
weight of the sample undergoing test is monitored continuously while the sample is
heated at a constant rate. The computer based mathematical model predictions for
volatile matter yield are verified with the experimental results and found to be in
good agreement.