Gasification of Shenhua Bituminous Coal with CO2: Effect of Coal Particle Size on Kinetic Behavior and Ash Fusibility

Abstract

Coal gasification is the process that produces valuable gaseous mixtures consisting primarily of H2 and CO, which can be used to produce liquid fuel and various kinds of chemicals. The literature shows that the effect of particle size on coal gasification and fusibility of coal ash is not clear. In this study, the gasification kinetics and ash fusibility of three coal samples with different particle size ranges were investigated. Thermogravimetric results of coal under a CO2 atmosphere showed that the whole weight loss process consisted of three stages: the loss of moisture, the release of volatile matter, and char gasification with CO2. Coal is a heterogeneous material containing impurities. Different grinding fineness leads to different liberation degrees for impurities. As for the effect of particle size on TG (thermogravimetry) curves, we found that the final solid residue amount was the largest for the coal sample with the smallest particle size. The Miura-Maki isoconversional model was proved to be appropriate to estimate the activation energy and its value experienced a slow increase when the particle size of raw coal increased. Further, we found that particle size had an important impact on ash fusion temperatures and small particle size resulted in higher ash fusion temperatures.