Research On Influencing Factors Of Measuring The Drilling Cutting Gas Desorption Index △h₂

The drilling cutting gas desorption indexâ–³h₂ is one of the most important indexes for prediction the coal and gas outburst. It is very difficult for us to obtain accuracyâ–³h₂ because of some factors in the measurement process ofâ–³h₂. Based on the foundational theory of gas desorption and diffusion and analyzed the process of gas diffusion through coal particles, the mathematical and physical model governing the gas diffusion of coal particles is established and the analytical solution ofâ–³h₂ is deduced. The variation of gas diffusion quantity with time at different granularity, different diffusion coefficients and different gas pressure were researched. The influence of exposure time, coal granularity, gas diffusion coefficient, absorption constants, gas press and gas content onâ–³h₂ was also studied, and the variation of error ofâ–³h₂ with exposure time error was studied. The results show that gas diffusion quantity increases with coal granularity decreasing, the diffusion coefficient increasing, gas pressure increasing at the same elution time. The desorption indexâ–³h₂ increases with granularity lowering, diffusion coefficient increasing, adsorption constant a elevating, adsorption constant b increasing, gas pressure rising and gas content increasing. Adsorption constant a andâ–³h₂ are in accord with linear relationship. Bothâ–³h₂ and gas content are also in accord with linear relationship. Gas press andâ–³h₂ are in accord with power relationship. Both absolute error and relative error ofâ–³h₂ increase with error of exposure time increasing.