A kinetic study on gasification characteristics of high-ash-fusion-temperature Huainan coal for non-slagging entrained flow gasification

Non-slagging entrained flow gasification provides a number of advantages for gasification of high-ash-fusion-temperature (AFT) coals in comparison with the traditional slagging gasification. To further explore the gasification characteristics of high-AFT coals and determine the gasification condition for non-slagging entrained flow gasification, a typical Chinese high-AFT Huainan (HN) coal is gasified in an isothermal thermogravimetric analyzer (TGA) at temperatures between 1100 and 1500 degrees C with CO2 partial pressure range from 4.5 x 10(4) to 7.5 x 10(4) Pa. Volumetric model (VM), shrinking core model (SCM) and random pore model (RPM) are used to fit the experimental data for determining the kinetics. Results show that the gasification reactivity of HN coal char increases with the increase in temperature, the activation energy is around 80 kJ center dot mol(-1), and the reaction order is 0.96, 0.78 and 0.69 with respect to VM, SCM and RPM, respectively. For all the investigated conditions, the RPM model better fits the experimental results. Thermogravimetry-differential scanning calorimetry (TG-DSC) and scanning electron microscopy-energy-dispersive X-ray analysis (SEM-EDX) technologies are applied to examine the ash fusibility of HN coal. The apparent ash fusion behavior is observed around the temperature of 1300 degrees C due to the partial melting of fayalite and almandite. To minimize ash fusion and coal ash agglomeration, a temperature of 1200 degrees C is suggested for non-slagging gasifying HN coal.