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

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 µm/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.