Large-scale simulation of gasification reaction with mass transfer for metallurgical coke: Model development

摘要

Large-scale simulation of gasification for a highly resolved coke model with hundreds of millions of voxels was carried out. Three-dimensional phenomena could be evaluated by the numerical simulation, while our previous study was limited to one-dimensional distribution due to the high computational load. The coke model was developed from micro X-ray CT images of a cylindrical coke sample with a radius of 20 mm, and the screen resolution was 20.6 mu m/pixel. In the resolved pores, the mass transfer with CO2 gasification was analyzed, whereas voxels of the coke matrix adjacent to the pore vanished due to the reaction. Coke was found to degrade non-uniformly as the reaction progressed, and the areas with highly concentrated carbon matrix voxels remained unchanged. These characteristic areas were derived from the X-ray CT images. Focusing on the concentration distribution of CO2, it was found that the rate-controlling step changed from pore diffusion to chemical reaction with structural change at 1573 K.