Experimental Study of Pre-oxidation Effect on Limit Parameters of Coal Secondary Spontaneous Combustion

Abstract

To study the effect of pre-oxidation on the limit parameters of coal spontaneous combustion, the primary oxidation and secondary oxidation processes of coal are simulated by the program heating device, the oxygen consumption rate, gas productivity, exothermic intensity and the limit parameters of coal spontaneous combustion are compared and analyzed in two oxidation processes. The results show that the oxygen consumption rate, gas production rate and exothermic intensity of oxidized coal and raw coal increase exponentially with the increase of coal temperature, but the indexes of oxidized coal are slightly higher than raw coal before 70 ℃ and lower than raw coal after 70 ℃. The upper limit of air leakage intensity for spontaneous combustion of oxidized coal and raw coal decreases first and then increases, while the lower limit of oxygen concentration and the minimum coal thickness increases first and then decreases. From the extreme value of the limit parameters of coal spontaneous combustion in the heating process, the threshold of spontaneous combustion of oxidized coal is lowered and easier to self-ignite.

Keywords

• pre-oxidation
• coal spontaneous combustion
• limit parameters
• secondary oxidation
• characteristic parameter