Study On Correction Of Interference Factors Of Dust And Methane Measuring Instruments In Coal Mines

Dust and methane detection has always been an important part of underground coal mine safety detection.Among many kinds of measuring instruments,light scattering dust meter and spectral absorption methane sensor are the most cost-effective and widely used.However,they are vulnerable to environmental interference,internal noise,device performance and other factors.The existing detection devices lack of correction for a variety of interference factors,which will cause great errors in actual coal mine environment measurement.They have both separated interference factors,and dust will interfere with methane measurement,so it is necessary to study them together.A spherical experimental chamber is designed to simulate the dust,methane and interferences in the underground environment of coal mine.The interference factors of dust detection by light scattering method and methane detection instrument by spectral absorption method in coal mine are analyzed and studied.The scheme of reducing interference and improving accuracy.Specific research contents are as follows:(1)The influence of particle size,shape,scattering angle,composition,environmental humidity,water mist,performance of hardware device and hardware circuit on the measurement of dust by light scattering method is analyzed through the formula of Mie theory and experimental results,and its reduction of dry dust,method of disturbing and improving the measurement accuracy are given.(2)The mechanism of methane concentration measurement based on spectral absorption method with NDIR and TDLAS technology.A system for methane detection is built by using tunable light source and harmonic detection method.The system is calibrated with methane standard gas,which realizes the accurate measurement of alarm concentration of methane in underground mine.The influence of temperature,humidity,pressure,water mist,dust and the performance of each module of the system on the measurement of light absorption method is analyzed through theoretical and experimental results.The important reference for improving the measurement accuracy is given.(3)A transparent environment simulation chamber of dust,methane and interference factors in spherical coal mine was built.It can produce dust environment with uniform and controllable concentration,methane environment with controllable alarm concentration and controllable interference factors(such as humidity and particle properties),and it has dust and methane detection system.It is mainly used to study the measurement experiment of interference effect under the mixed state of dust and methane in coal mine.The function of real-time monitoring and wireless transmission of environmental parameters in the balloon cabin is realized.At the same time,the upper computer software for controlling and monitoring the whole balloon cabin internal environment is compiled.(4)The concentration distribution of aerosol particles in a spherical environment simulation chamber was simulated.Using ANSYS-Fluent fluid simulation software,the dust concentration distribution in spherical environment simulation chamber was simulated,and the optimal design of rapid dust mixing in the flow field was realized.In this paper,the interference factors of light scattering dust meter and spectrum absorption methane sensor in underground mine are studied.The main purpose is to simulate the characteristic environment of underground coal mine by building an experimental cabin,and measure the interference factors experimentally,so as to get the correction scheme.However,due to the complexity of dust characteristics in the actual situation,there are still some deficiencies in the correction model of dust characteristics.In addition,the cost of the whole device for measuring methane is too high,which needs further study and solution.