Effect of oxidation treatment on structural characteristics and combustion behavior of residual carbon from coal gasification fine slag

Abstract

Improving the combustion reactivity of residual carbon (RC) is an important prerequisite for effective combustion of coal gasification fine slag (CGFS). This study investigates the oxidation of RC using air and CO2. Compared to raw RC, the oxidation process results in a lower burnout temperature of oxidized RC, and reduced combustion time. Additionally, RC oxidized by CO2 shows better combustion performance than that oxidized by air. The enhanced combustion performance of oxidized RC primarily stems from structural modification. The combustion behavior of oxidized RC is jointly determined by its carbon microstructure, functional groups, and pore structure, with pore structure being the predominant factor. Furthermore, increasing the oxidation temperature facilitates the formation of small-sized pore structures on the surface of the oxidized RC, which promote the oxygen diffusion and the heat transfer during combustion. However, the pore collapse caused by excessive oxidation inhibits the combustion performance of the corresponding oxidized RC.