Abstract
The purpose of this study is to clarify the relationship among the reactivity of coal char, the carbonaceous structural change, and the ash behavior. The steam gasification of various coal char was carried out in a fixed-bed reactor. After the gasification, the reacted char was analyzed by LRS (Laser Raman Spectroscope), and SEM/EDX (Scanning Electron Microscope, Energy Dispersive X-ray Spectroscopy). In order to evaluate the progress of carbonaceous graphitization, we observed ID/IV ratio that was one of the Raman parameters. As a result, graphitization of coal char was equally observed under every condition as the increasing of conversion rate. So we estimated that the progress of graphitization would be caused with following reason. Disordered carbon structure, whose reactivity was higher, had been gasified alternatively, consequently the ratio of carbon that had graphitic structure increased relatively.Then in order to clarify the ash behavior affecting the char reactivity, characterizations of each char was carried out using SEM/EDX. From the results of observing SEM image and EDX-mapping, we found the different behavior of elements and novel parallel analysis between EDX-mapping and LRS-mapping was very effective for the comprehensive evaluation of ash behavior and carbonaceous structure. As the gasification reaction, the reactivity of char was partially decreased, because the surface of carbon had been covered with certain elements such as Si, and reaction gas could not contact with the carbon.
