Mathematical modelling of 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 the 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 coke ovens of Tata Steel. 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