Self-activation Theory And Process Of Spontaneous Combustion Of Coal

Based on mechanics of fluids in porous media and theory of heat and mass transfer, the mathematical model is set up. According to the model, oxygen consumption rate and heat liberation intensity of coal, diffusion coefficient and osmotic coefficient of oxygen is confirmed for key parameter to numerical simulation of coal self-ignition process, and these parameters are researched and test by experiment. And set up the mathematical model of whole process of self-heating of coal in one-dimensional.Furthermore, based on dynamic equation of coal's adiabatic oxidation, the simulation system for the process of spontaneous combustion of coal is worked out. And the spontaneous combustion simulation using small coal sample was carried out, which is the first successful case nationwide. And coal's ideal (under the condition of thermal insulation) temperature-rise curve is obtained by doing simulation experiments on nine coal samples in different moisture content, rank and ash content. And obtained some rule about those factors effecting in orientation on self-heating of coal.Based on analyzing data from adiabatic testing, the rule that activation energy descend gradually with temperature rise was obtained, which shown that energy that activate active structures in coal is getting low as the temperature rises. It is easier to activate it at more high temperature.And based on theory of activation reaction, the simulated experiments and the characters in process of spontaneous combustion of coal, such as index gases, generation heat rate and coal structures changes, the Self-activation Theory of Spontaneous Combustion of Coal is put forward: The process of self-heating of coal is that the different function group (active structures) in coal is activated early or late, and reactive with oxygen and release energy to make the temperature raise. With the higher temperature, active structures are easier to active with lower activation energy. So, active structures are easier to active more and more with temperature rise, and oxidize respond more and more violent, heat releases more and more, the temperature rises also more and more quick, keep accelerating to ignition.According to analyses changing rule of activation energy in different temperature range at different coal, the Zero-Activation Energy Theory was put forward: Activation energy amount zero. Zero-Activation Energy is a transition value from positive to negative; it means oxidize with coal turning to self-oxidize.