Modeling the Coal Tar Pitch Primary Carbonization Process

Abstract

The properties of the carbon materials obtained as the final product of coal tar pitch carbonization process are a consequence of the type of chemical and physical phenomena occurring through the process. A new simplified approach for modeling of the primary carbonization is presented to provide the semi-quantitative knowledge about the process useful for improving the efficiency of the industries that deal with this process. The proposed approach is based on defining thermodynamic and kinetic equations simply representing numerous phenomena happening during primary carbonization. Partial pressures of emitted volatiles in a simple pitch system are studied. The model enables estimating the mass and enthalpy changes of pitch through thermal treatment consistent with experimental data for mass losses of pitch heat treated up to 550 °C. Application of the model to describe molecular weight distribution changes of pitch during primary carbonization is demonstrated, showing a good agreement between the presented results and the investigations reported by Greinke. For the first time, the effect of important parameters in pitch carbonization, such as the heating rate of the pitch and the carrier gas flow rate, on the emission rate of volatiles is successfully modeled. The present model is well able to estimate the energy requirement for thermal treatment of pitch up to 350 °C.