Abstract
Coal and gas outburst is still a major safety problem in the process of coal production in China. Correctly understanding of the migration law of outburst high gas and pulverized coal is an important basis for accurately predicting the occurrence time and possible scope of outburst. To reveal the airflow disturbance characteristics and coal-gas flow rule in coal and gas outburst process, outburst coal-gas migration simulations under different gas pressures were conducted using a self-developed visual outburst dynamic effect test device. The results showed that coal-gas flow state at the outburst port is divided into subcritical flow, critical flow, and supercritical flow state. The pulverized coal-gas flow migration in the roadway space can be divided into coal gas two-phase flow area, air compression area, and undisturbed area. Under the experimental conditions, the maximum propagation velocities of wave are 342.22~359.21 m/s, and the coal gas two-phase flow is far less than the propagation velocities of outburst wave, just 3.68~33.33 m/s. When the outburst energy is large, multiple compression waves can superimpose to form shock waves. The peak value of the wave does not necessarily appear in the first boosting range. The presence of pulverized coal leads to a faster attenuation of shock wave, but it makes a greater dynamic destructive force at the same speed.
Highlights
Coal has always been China’s most important energy source
Under 0.3 MPa and 0.5 MPa gas pressure conditions, it was evident that multiple compression waves and expansion waves were generated in the roadway after the outburst, but this may have been caused by the fact that the total energy involved in the outburst was small, and the compression waves were not superimposed to form a shock wave
To reveal the airflow disturbance characteristics and coal-gas flow rule in coal and gas outburst process, outburst coal-gas migration simulations under different gas pressures were conducted using a self-developed visual outburst dynamic effect test device; the following conclusions can be drawn: (1) The outburst coal-gas flow experienced four stages and the migration of outburst coal lagged behind the initial airflow disturbance in the roadway space
Summary
Coal has always been China’s most important energy source. In 2019, coal consumption accounted for 57.7% of the country’s total energy consumption [1]. Several measures and policies have been enacted to prevent and control outburst disasters, such as shutting down a large number of outburst mines, encouraging the development of new technologies, and issuing new rules for the Prevention and Control of Coal and Gas Outburst. Compared with 2012, the number of outburst accidents and deaths in 2019 decreased by 66.7% and 63.6%, which is close to the reduction in the number of coal mines (62.1%).
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