Capsule-mucus Sealing Technology Based On Oxygen Candle

Gas pressure measurement in underground coal seams plays a vital role in the control of gas disasters.After many years of underground use,the traditional hole sealer has been exposed to many problems during use:the sealing is not strict,the time is long,the measuring system is complicated,and so on.Based on the previous research,this paper proposes a capsule-mucus sealer based on oxygen candle,combined with wireless pressure measurement technology to achieve rapid sealing,integration and improve sealing quality.The new type of hole sealer is mainly composed of two sets of capsules,capsule connecting parts and sealing mucus,liquid storage tube,expansion tube and stainless steel hole tube.The principle of sealing:artificially triggers the oxygen candles in the two sets of capsules,so that it generates a large amount of gas independently,and generates a certain pressure in the capsule,the capsule expands in close contact with the borehole wall,and the expansion tube squeezes the mucus in the liquid storage tube The mucus penetrates into the gap and the crack through the stainless steel orifice tube to complete the sealing.In the paper,NaClO₃ is selected as the main component of the oxygen candle.The oxygen candle is ignited by electric triggering to react the oxygen candle.Several common oxygen candle catalysts（Co₃O₄,Co₂O₃,Fe₂O₃,MnO₂,CuO）and fuel（magnesium powder）are pressed.Different ratios were mixed with NaClO₃ to carry out the proportioning experiment.The results of the experimental results showed that the catalyst with the best catalytic effect and the proportion of each substance were different.The final ratio of oxygen candle was determined as:sodium chlorate A%,Co₃O₄ C%,magnesium Powder E%,diatomaceous earth F%.Based on the design idea of the new type of hole sealer,the pressure parameters in the capsule were studied with the help of experiments.The pressure test device was designed and improved,and the oxygen candle which was prepared in advance was put into the device,and the pressure test was carried out.The stress test experiment is mainly carried out in three parts:the maximum pressure test of the fixed volume,the maximum pressure test of the fixed oxygen candle mass,and the equilibrium pressure test of the fixed volume.The factors affecting the pressure and the conditions for satisfying the sealing requirements are studied.The results show that the temperature is constant,and the factors affecting the pressure are mainly the mass of the reactant（oxygen candle）and the volume of the reactor chamber.When the ambient temperature is constant,the maximum pressure and equilibrium pressure are proportional to the mass of the oxygen candle,and inversely proportional to the volume of the reactor chamber.Fitting relationship is P’=0.0110*m’-0.6636*V’+1.7414 and P’’=0.0104*m’’-0.6779*V’’+1.631.In actual engineering,the pressure of the capsule-mucus sealer should reach 3 MPa,and the design size of the capsule is 70 mm in diameter and 1.30 m in length.Therefore,the required oxygen candle mass is 457 g.