Fragmentation model of coal devolatilisation in fluidised bed combustion

Devolatilisation is the release of volatile compounds from coal matrix by thermal decomposition. During coal devolatilisation, fragmentation could occur due to pressure build-up of accumulated volatiles. A fragmentation model is necessary to ensure the safe operation of coal combustion and optimum process condition. In this study, the refinement of fragmentation model of coal devolatilisation was done. In order to obtain a comprehensive model, a fluidised bed combustion experiment was conducted using two Indonesian coals (Musi Banyuasin and Berau) and the results were then compared with the model simulation. Using a coal diameter of 0.8-17 mm at a combustion temperature of 850 degrees C, it shows that the fragmentation probability and number of fragments could be affected by the coal particle diameter, convective pore diameter, and porosity. Predictions made by the developed model were close to the experimental fragmentation data, with an error range of less than 5.1%.