Research Of U-Type Ventilation Working Face Fire Prevention And Extinguishing Technology By Full-Section Curtain Nitrogen Injection

Nitrogen injection technology,for preventing and controlling gob spontaneous combustion,is widely used in domestic coal mines.At present,many studies have been done in gob nitrogen injection for preventing and controlling fire.However,problems with poor inerting effect and high cost frequently occur.Basically,this is because the gob nitrogen injection pipe layout and the nitrogen flow control are unreasonable.Taking Face B1003W01 of Shajihai Coal Mine as the research object,a method of fire prevention and extinguishing of full-section curtain nitrogen injection was studied by means of theoretical analysis,laboratory experiment,numerical simulation and field test.It was applied to the U-type ventilation face.According to the characteristics of air leakage in the U-type ventilation face,the nitrogen migration law is studied,which lays the foundation for the rational arrangement of nitrogen injection pipeline.The critical oxygen concentration of B10 coal seam was determined by the experiment of temperature programmed experiment,which provided the index for determining the lower boundary of oxidation zone.By analyzing the seepage characteristics of the stope,a mathematical model of nitrogen injection in the gob was constructed.The initial values were optimized by inversion method,and the distribution of oxygen concentration field in gob under different nitrogen content was simulated,and the optimal nitrogen flow rate was obtained.According to the gas release model theory,the release process of nitrogen is revealed.The key parameters of the whole curtain nitrogen injection technology were studied,and the curtain fire suppression technology was built and applied in Face B1003W01 of Shajihai Coal Mine.By comparing the results of the numerical simulation and the measured data of the curtain nitrogen injection,the two are in good agreement with each other,which is a good way to verify the effectiveness of the full-curtain curtain injection technology.After the nitrogen injection,the oxidation zone was greatly advanced,and the shrinkage was significant,indicating that the inerting effect was significant.