The Design Of Full-Scale Methane Detector Based On Double-Sensitive Modes

Mine gas monitoring has been the focus of China's coal mine safety work.Catalytic combustion gas sensor has advantages of high sensitivity,fast response and low cost and so on.However,when detecting high concentrations of methane,the heat generated by the reaction catalytic causes irreversible damage to catalytic combustion gas sensor,that is,the impact of high concentrations problem;and the two-value problem exists at the same time.Due to unreasonable design,the gas explosions are caused by the burning of catalytic combustion sensitive components when gas sensor is working at high-temperature in high concentrations of methane gas.Therefore,mine methane detection technology with full range has become a key technology of coal mine safety production,which has an important significance to improve the stability of the mine gas monitoring products,the impact ability,and coal mine production safety.The paper has analyzed the theories and studied the measurement methods of catalysis combustion type gas sensor about its thermal conductivity and catalytic combustion characteristics,studied and identified the mathematical model,proposed the research method of full-scale methane detector based on double sensitive modes.Based on the design parameter indexes and the functional requirements of the methane detector,this paper has analyzed the detection methods in detail,compensated zero drift and sensitivity attenuation,and get specific solutions of low and high concentrations of methane gas.With the use of the constant temperature power supply mode,sensor works more stable and reliable.The hardware circuit designs of methane detector are the circuits of MCU minimum system,power management,signal amplification,reference voltage source,infrared receiving,data output and display.Circuit debugging is based on these circuits.System software designs of methane detector include theprograms of main,the acquisition and processing of concentration data,remote control decoding,calibration and key service.In this paper,experiment tests have been carried out about full-scale methane detector based on double sensitive modes;preliminary tests have been done to observe the influence of the ambient temperature to catalytic combustion gas sensor;Tests of methane's temperature and sensitivity comparison before and after have also been done.The results show that: the detector has high measurement accuracy,significantly enhances anti-jamming capability,is easy to repair and maintenance.It can be achieved full-scale methane detection by using a single catalytic combustion sensor.