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

The present paper addresses thermal annealing of coal under the combined effects of temperature and pressure. articles were pyrolysed in a pressurized heated grid reactor with heating rate of 5000 °C/s up to 1600 °C. The pressure during heat treatment was set to values in the range 1–12 bar. After heat treatment char samples were collected and subjected to:1. rmal and non isothermal thermogravimetric analysis, in order to measure their reactivity towards oxygen, carbon dioxide and mixtures of oxygen–carbon dioxide. d porosimetric analysis in order to investigate their structure. light scattering particle analysis in order to assess the extent of fragmentation experienced during heat treatment. s 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.