石炭の常温域からの自然発火: 等価酸化時間の導入による数値解析

This paper describes calculation concerning the temperature rise and the oxygen diffusion processes of a coal seam in the low temperature range. The temperature rise of coal occurs by the accumulation of heat produced by oxidation on the coal surface. The heat generation rate is a function of temperature, oxygen concentration and the exposure time of coal to an oxygen atmosphere. For the case where the oxygen concentration and the temperature around the coals vary with time, we have proposed a new method for estimating the heat generation rate. The authors have called this new method 'exposure equivalent-time'. This new method was applied successfully to simulate the temperature and the oxygen concentration in the coal seam model whose open-ends are exposed to the air. The finite-difference method was used to solve the equations of heat conduction and diffusion of air.