Research and practice on low-temperature nitrogen fire prevention and extinguishing technology in segmented goaf of steeply inclined and thick coal seams
The nitrogen injection fire prevention and extinguishing technology is commonly used as the main technical measure to pre-vent spontaneous combustion of residual coal in goaf during mine production.However,due to the lack of cooling characteristics of nor-mal temperature nitrogen on goaf,it cannot effectively eliminate high temperature points in goaf.The FLUENT was used to simulate the flow field and temperature field changes in the goaf before and after low-temperature nitrogen injection under current working condi-tions,and the optimal low-temperature nitrogen injection scheme was further selected.Subsequently,a nitrogen cooling device was used on-site to transport low-temperature nitrogen to the goaf,studying the effect of low-temperature nitrogen on oxygen and temperature in the goaf.The results showed that after nitrogen injection into the goaf,the area of the dispersion and oxidation zones in the goaf significantly decreased,which was less than half of that before nitrogen injection,and there was a significant increase in the suffocation zone;after in-jecting low-temperature nitrogen,the temperature of the goaf gradually increased in an elliptical shape with the nitrogen injection port as the center;the on-site nitrogen injection plan with a temperature of-40℃,a nitrogen injection port position of 10 m,and a nitrogen in-jection rate of 750 m3/h was selected.The real-time monitoring results of the temperature measurement fiber showed that the tempera-ture of the nitrogen injection port decreased by 48.8 ℃ compared to injecting normal temperature nitrogen,and the temperature of the goaf on the return air side decreased by 19.1 ℃ compared to injecting normal temperature nitrogen.
goafspontaneous combustion of residual coallow-temperature nitrogen"three zones"of spontaneous combustion in goafnumerical simulation
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