Study on the influence of liquid nitrogen injection cooling in gob on the thermal physical characteristics of coal spontaneous combustion

Abstract

In order to study the effect of liquid nitrogen injection cooling on spontaneous combustion of coal, coal samples from the second and third panel areas of Tingnan Coal Mine were selected for thermal and physical property experiments. First, the coal sample was pretreated by LFA457 laser flash analyzer, and then the thermophysical property parameters of the coal sample were measured in the range of 30-300 ℃, and the change law of the thermophysical property parameters of the coal sample with temperature was obtained after liquid nitrogen injection and cooling, and the factors affecting the thermophysical properties of the coal sample were compared and analyzed. The results show that the thermal diffusivity decreases with the increase of temperature, and the specific heat capacity and thermal conductivity increase with the increase of temperature; in the range of 30-200 ℃, the average change rate of thermal property parameters of coal samples after liquid nitrogen injection treatment is higher than that of raw coal samples, indicating that liquid nitrogen injection treatment will increase the sensitivity of coal samples to temperature; in addition, at the same temperature, the thermal physical property parameters of coal samples after liquid nitrogen injection treatment increased to different degrees compared with the original coal samples, and the average growth rate of thermal diffusion coefficient was the highest, indicating that the thermal diffusion ability of coal samples after liquid nitrogen injection treatment was enhanced during the oxidation and heating process.

Keywords

• gob
• liquid nitrogen injection cooling
• coal spontaneous combustion
• thermal diffusion
• thermophysical parameters