Investigation into Distribution of 'Three Zones' of Spontaneous Combustion in Gob of Fully Mechanized Top-Coal Caving Workface by Means of Numeric Simulation

摘要

Study of the "Three Zones" in gob is important for predicting and preventing spontaneous combustion in coalmine. A dimensionless steady coupled model of air flow diffusion and chemical reaction in loose coal of fully mechanized top-coal caving mining workface (FMTCCMW) is setup. The model is solved numerically to obtain distribution of oxygen concentration and air flue, the "three zones" which includes heat dissipation zone, self-heating zone and chocking zone of spontaneous combustion is then partitioned in the FMTCCMW gob henceforth. Numeric simulation with varied pressure grade in the workface and oxygen consumption rate of coal shows that as oxygen consumption rate of coal rises, oxygen concentration declines while air leakage intensity almost keeps constant in the gob; as pressure grade in the workfaee increases from 0 Pa, width of self-heating zone in the gob increases first, then attains maximum value and decreases afterward.