Low temperature oxidation of coals—a calorimetric study

Equivalent Oxidation Exposure - Time for Low Temperature Spontaneous Combustion of Coal

“…Finally, the hot spot appears on the outside surface of the stock, which marks the start of spontaneous. Kaji et al (1987), shown in Fig. 3, and Miyakoshi et al(1984).…”

“…Kaji et al(1987) has reported that the coals have almost the same activation energy of around E=50 kJ/mole for temperature range of 20 to 170 °C. On the other hand, Miyakoshi et al (1984) reported as E ≈ 20 kJ/mole for Japanese coals in temperature range lower than 50 °C based on measurements of oxygen adsorption heat using with a micro-calorimeter.…”

“…The initial order of heat generating rate of coal for exposing air is q(0) ≈ 0.01 to 0.001 kW/kg. Kaji et al (1987) measured rates of oxygen consumption due to coal oxidation in the temperature range 20 to 170 °C using coals ranging from sub-bituminous to anthracite coal. They reported that heat generated per unit mole of oxygen at steady state is h = 314 to 377 (kJ/mole), and their results of the Arrhenius plots, the oxygen consumption rate versus inverse of absolute temperature T -1 (K -1 ), shows the Arrhenius equation.…”

“…The reaction heat of unit volume of oxygen was evaluated as ΔH ≈ 16 (J/cm 3 O 2 ) based on the experimental results of heat generation rate by Kaji et al(1987) and Miyakoshi et al(1984) shown in Fig. 3.…”

“…Miyakoshi et al(1984) proposed an equation guiding heat generation in crushed coal via oxygen adsorption based on a micro calorimeter. Kaji et al (1987) measured heat generation rate and oxygen consumption rate of three types of crushed coal at constant temperatures. They presented an equation to estimate heat generation rate against elapsed time.…”