Equilibrium Modeling and Optimization for Gasification of High-Ash Indian Coals by the Gibbs Free Energy Minimization Method

Abstract

This article presents a non-stoichiometric equilibrium model based on the Gibbs free energy minimization method to analyze the effect of process parameters (temperature, pressure, equivalence ratio (ER), and steam/coal (S/C) ratio) on gasification of high-ash Indian coal and to find out optimum operating conditions for production of energy and chemicals. The model considers 16 elements distributed among 373 gas and 119 solid species. Effect of temperature is small when temperature is increased above ~ 1100 K. While increase in pressure brings operational benefits, effect of pressure on the gasification performance is very small. In general, with increase in ER, oxidative species start to dominate and, consequently, cold gas efficiency (CGE) decreases and carbon conversion (X) increases. CGE increases with increase in S/C ratio. The proposed methodology can be used for preliminary analysis and optimization of gasification system effectively in terms of cost and time.