Simplification of Gibbs Free Energy Equation for Predicting the Gas Composition of Steam Gasification of Pattukku Coal Char

Abstract

One of the method to utilize coal as a source of fuel is to convert the coal into a synthetic gas through the process of gasification. The composition of the gas formed greatly depends on the gasification agent and the process conditions. Currently, some researchers have developed a mathematical model based on thermodynamics to predict the gasification gas composition, based on Gibbs free energy. The equations used to calculate the Gibbs free energy are relatively complex. This study proposes simpler equations to predict the gas compositions in the form of correlation of component’s Gibbs free energy and temperature. The simpler equations proposed were then tested by the experimental data of steam gasification of Pattukku coal char. Base on the result of the experimental and calculation showed if the temperature of gasifier increase by 100^oC, the volume of gas will increase by approximately 1.5 times. The largest average of error obtained for model 1 is 22.95% while from model 2 is 23.45%. The calculation showed that the proposed model could quantitatively be applied to predict the gas composition of steam gasification of Pattukku coal char.