Investigation on co-combustion of coal gasification fine ash and raw coal blends: Thermal conversion, gas pollutant emission and kinetic analyses

Abstract

Coal gasification fine ash (CGFA) is produced in huge quantities, has high carbon content and fine particle characteristics, and is environmentally polluting and energy wasting. Co-combustion of CGFA and raw coal (RC) is a way to recover CGFA energy. The aim of this work is to investigate the effects of thermal conversion, synergistic behaviour, kinetics, thermodynamics and gas release behaviour (especially of polluting gases) during the co-combustion of CGFA in air atmosphere. The results showed that the addition of RC to CGFA reduced the activation energy of the mixture and improved the combustion performance and combustion stability of CGFA, and the combustion performance of the mixture with 30% CGFA was comparable to that of Yangquan anthracite. A significant synergistic interaction between CGFA and RC occurred during the co-combustion process, and this interaction inhibited the formation of gaseous pollutants, especially reducing the formation of gaseous emissions (NH3, NO, NO2 and SO2). Average activation energy was described using four iso-conversion and integral master plots methods. The co-combustion for CGFA and RC were best described by the reaction order and random nucleation mechanisms. Our results contribute to developing the new strategies of energy with the CGFA combustion.