Thermal Characteristics Analysis of Conveyor Belt During Ignition

Abstract

ABSTRACT Conveyor belt fires are the most serious fires that occur exogenous mine fires. To study the thermal characteristics of the PVC conveyor belt during the fire process, the softening characteristics of the conveyor belt underground in the mine were simulated by using the temperature rise oxidation system. Based on the C600 microcalorimeter, the oxidation heat release law of the PVC conveyor belt and pulverized coal with different softening temperatures was studied at an environmental range of 40–500°C, and the combustion law, heat release and heat absorption, HRR,combustion stages and activation energy were analyzed. The results show that with increasing softening temperature, the law of heat absorption and heat release of the PVC conveyor belt in the initial stage of the independent reaction is opposite, while the heat absorption and heat release in the coupling with pulverized coal increase gradually, and 106% and 107% more heat is released in the rapid development state than in the independent reaction state. The change rule of the heat release acceleration of the PVC conveyor belt remains basically the same whether it is alone or coupled with pulverized coal. The maximum difference in heat release acceleration increases with increasing softening temperature. According to the division of the combustion stages of the conveyor belt according to the heat flow value, when the PVC conveyor belt reacts alone, the temperature range of the heated softening zone is approximately 140°C smaller than when it is coupled with pulverized coal, and the temperature range of the melting pyrolysis zone is expanded by 100°C.It shows that when the conveyor belt is coupled with pulverized coal, fire is more likely to occur and the fire risk is greater. The average HRR at the softening temperature of 100°C is the largest, the ignition time is the shortest, and the danger is the greatest. The activation energy decreases with increasing softening temperature when it is coupled with pulverized coal, indicating that the higher the softening temperature is, the more likely an oxidation reaction will occur. The heat release characteristics and combustion stages division of the conveyor belt proposed in this paper have certain guiding significance for the replacement and maintenance of mine conveyor belts and the prevention and control of mine fires.