Effect of periodic wide atmospheric pressure change on CO emission in closed goaf

Abstract

Atmospheric pressure fluctuation is one of the most important factors affecting the climate environment and gas emission in the fire area. To obtain the influence rule of the surface atmospheric pressure change on the gas sampling and abnormal emission in the mine closed goaf, the No. 1 coal mine in Dananhu was taken as the research object. Using Fourier transform and Fisher harmonic analysis and other statistical methods, the influence of the periodic variation of atmospheric pressure on the gas leakage and outflow in the closed goaf was studied. The results showed that there were three atmospheric pressure periods of 15.2 d, 1 d and 182.2 d, and the probability was greater than 95%. The time period with the highest number of atmospheric pressure peaks was 7:00–8:00, which accounted for 20.2% of total occurrence number in a day. And the time periods with the highest number of atmospheric pressure trough were 2:00, 15:00 and 16:00, accounting for 27.4%. The peak-to-trough transition time was mainly concentrated around 6 h, and the diurnal variation curve of atmospheric pressure was mainly bimodal. The atmospheric pressure change rate was mostly concentrated in 10–50 Pa/h. It was determined that the distance that the gas sampling pipe was pre-laid into the inner side of the closed wall should be greater than 44.4 m, and the CO concentration and atmospheric pressure in the closed goaf were both periodic and negative with atmospheric pressure. The research results have important guiding significance for the monitoring, early warning and environmental protection of the goaf.