Effect of Frequency Conversion Ventilation on Coal Spontaneous Combustion

Abstract

ABSTRACT The frequency conversion ventilation has achieved good results in the practical application of preventing the gas concentration of the coal mining face exceeding the limit. However, its impact on the spontaneous combustion of coal in the goaf is uncertain. Therefore, this paper studies the spontaneous combustion of three types of coal samples at different ventilation rates under frequency conversion ventilation. The results show that frequency conversion ventilation can reduce the average CO concentration compared with constant ventilation, and the inhibiting effect will weaken with the average ventilation rate increased. In three variable frequency ventilation rates, the rate of 10-30-50cm3/min has the best inhibiting effect. At this condition, the inhibiting effect is related to the type of coal, the inhibition rate on anthracite and lignite is proportional to the temperature, while the inhibition rate on bituminous coal is inversely proportional to the temperature. During one cycle around 120°C, the heat released by the oxidation reaction of bituminous coal, lignite, and anthracite decreased by 0.030 J/g, 0.144 J/g, and 0.034 J/g, respectively. Thus, the frequency conversion ventilation can affect the elementary reaction of coal, resulting in a reduction in the heat release from the coal oxidation reaction.