2023 Volume 63 Issue 9 Pages 1487-1495
In recent years, three-dimensional (3D) measurements of actual coke particles have been conducted using a laser scanner in order to acquire knowledge about the gas/liquid permeability of blast furnaces. In order to ensure representativeness, a large number of coke particles need to be measured during actual operation. Therefore, we measured over 100 coke particles using a medical X-ray computed tomography (CT) scanner and obtained 3D shape information of each particle using image analysis. The validity of the proposed method was confirmed by comparing the analysis results with the actual measurement results from sieve separation. In this study, we mainly focused on the sphericity and flattening ratio as 3D shape indices. A 10 kg sample contains coke with a wide distribution of sizes and shapes, and the standard error in addition to the mean value should be considered when comparing samples with different production conditions. The results of the analysis targeting two samples with different manufacturing conditions showed that the sphericity was greatly affected by the impact of the transportation process and closely related surface breakage. Furthermore, the flattening ratio was greatly affected by the fissures formed during the carbonization process, which is closely related to the furnace temperature and volatile matter of the blended coal. This study shows that a medical X-ray CT scanner is a useful and practical tool for acquiring 3D shape of coke particles.
