High-temperature area migration characteristics of loose coal spontaneous combustion based on experimental scale of semi-enclosed experimental system

Abstract

According to the actual combustion characteristics of loose coal, and in view of the advantages and disadvantages of the existing research equipment for the high-temperature area, a simulated experimental device for the development of coal fire was designed and fabricated. The coal sample of Mengcun coal mine in Xianyang, Shaanxi Province China as the research object, the device was used to simulate the combustion of loose coal, and the distribution and movement of high-temperature area during the combustion were studied. The temperature change of the high-temperature area was obtained from normal temperature to ignition. The results showed that during combustion, the temperature rose first with the increase of time and then decreased. When the temperature reached 309.5 °C, the coal sample started to combustion. In addition, the temperature decreased to the ambient temperature after 600 h. The high-temperature area of the selected coal sample was concentrated in the middle part and the back part of the furnace, which was for the poor thermal conductivity, water evaporation of coal intrinsic quality. Moreover, the temperature decreases in turn during the downward propagation of the high-temperature area in the depth. And its decline to the limit oxygen concentration (1%∼3%) is similar to reaching the combustion point temperature. Due to the influence of water content, pore and oxygen concentration, the movement of oxygen concentration and high temperature areas are mainly moved to the position and crack direction near the wind direction of coal-like combustion, showing nonlinear movement rules.