Effect of random pore shape, arrangement and nonadhesion grain boundaries on coke strength

In this study, the rigid bodies-spring model (RBSM) was used to numerically investigate how the fracture behavior of coke is affected by pore structure and non-adhesion grain boundaries. To study the effects of pore structure, randomly shaped pores were generated and randomly positioned in a coke matrix. The random shapes of pores were controlled by pore roundness and their random sizes were controlled by equivalent circle diameters. Non-adhesion grain boundaries were also randomly located in the coke matrix. First, results for a coke model with realistic pore structures showed that large distorted pores decrease coke strength. Second, fracture behavior was analyzed for a coke model composed of a coke matrix, pores, and non-adhesion grain boundaries. Coke strength decreased as the number of non-adhesion grain boundaries increased; these numerical results agreed with previous experimental data. Further, coke strength decreased even in the presence of only a relatively small number of non-adhesion grain boundaries. This is because, when non-adhesion grain boundaries occur in stress-concentrated regions, those boundaries become origins for fracture. This indicates that the presence of non-adhesion grain boundaries is one factor that decreases the strength of coke when it has been blended with low-quality coal.