Effect of Lignite Addition on Gasification Properties and Coke Strength after Reaction

Abstract

In order to clarify the effect of lignite addition on the CO2 gasification properties and strength after reaction of coke, the carbon structure, micro morphology, specific surface area of coke were studied by X-ray diffraction (XRD), scanning electron microscope (SEM) and BET. The results show that the lignite can decrease the coke strength after reaction, especially for the lignite content in coke more than 8%. The results of X-ray diffraction profiles show that the change of the carbon structure has no connection with the addition content of lignite, and is not responsible for the decrease of the coke strength after reaction. However, because of the consume of isotropic and fine mosaic textures enhanced by lignite addition during gasification, the generation, enlargement and coalescence of coke pores were promoted, leading to the increase of specific surface area. With the addition content of lignite increasing, the homogeneous reaction, which is transition from surface reaction to, enhanced the permeation of CO2 gas further into coke. The external reaction of lignite-enriched coke accelerated the rupture of bonds between coke particles, which results in the decrease of coke strength after reaction.