Thermal annealing of coal at high temperature and high pressure. Effects on fragmentation and on rate of combustion, gasification and oxy-combustion

Results show that upon heat treatment coal particles undergo severe thermal annealing and extensive fragmentation. For a given temperature of heat treatment, the effect of pressure of char preparation turns out to be non monotonous: at 1500 °C both char porosity and reactivity pass through a minimum at pressure in the order of 2-5 bar. The probability of fragmentation and the degree of graphitization follow a specular trend, with a maximum at pressures of 2-5 bar.