Abstract
The strength of the coke with the low-quality coals is related to the non-adhesion grain boundaries. Therefore, the effect of the boundaries on the coke fracture was numerically investigated. A coke model reproducing the actual boundaries was developed by the random arrangement of the coal particle polygons and expansion of the polygons based on experimental results. Then, the fracture behavior and strength of the coke model were analyzed using the Rigid Bodies-Spring Model (RBSM) method. The boundaries were generated around the low-quality coals in the model and the predicted amount of the boundaries corresponded with the experimental results. Therefore, the present coke model reproduced the generation of the actual boundaries. Furthermore, the size and complexity of the boundaries increased with an increase in the low-quality coals. In the model, springs at the gap or edge of the boundaries were fractured. The boundaries themselves were found to concentrate stress, and the arrangement and shape of the boundaries were supposed to affect the coke fracture. Moreover, the concentrated boundaries were thought to decrease the coke strength. Stress-strain curves showed that the coke with the larger blending ratio of the low-quality coal fractured with the weaker strength because of the increment in the size and complexity of the boundaries. The calculated fracture strength showed the same pattern as the experimental one in the higher blending ratio of the low-quality coals. Above all, the present method can predict the coke strength with the non-adhesion grain boundaries on the basis of the blending ratio of the low-quality coal.
