In-situ study on gasification reaction characteristics of Ningdong coal chars with CO₂

Meihuajing coal and Yangchangwan coal from Ningdong, China are chosen as raw materials to study char gasification reactivity using thermogravimetric analyzer and in-situ heating stage microscope, and typical gasification coal-Shenfu bituminous coal char is used as reference char sample. The char physicochemical properties are systematically characterized. The results show that the order for gasification reactivity of 3 chars at the same gasification temperature is Yangchangwan char > Meihuajing char > Shenfu char. In-situ study of heating stage microscope shows that with the progress of char-CO₂ gasification, most of char particles react with CO₂ as shrinking particle mode, and the particle reaction form changes from shrinking particle mode to shrinking core mode at high carbon conversion level. Additionally, it can be found from the results of shrinkage ratio variation of the particle projected area during gasification that Yangchangwan char shows the largest shrinkage area when undergoes the same reaction time, followed by Meihuajing char and Shenfu char. The difference in gasification reactivity is mainly attributed to the difference of physicochemical properties of chars. i.e., Yangchangwan char shows the largest specific surface area and the total contents of K, Na and Ca and the lowest order degree of carbon structure, followed by Meihuajing char and Shenfu char.