The Development Of Thermal Conductivity Full-scale Methane Transmitter

Coal mine safety production has always been a focus for the energy industryin China; gas explosion is the main risk that is a serious threat to the coal minesafety production. Because of the high gas coal mine gas concentration span, itsprocess of recycling and utilization requires effective detection. Therefore, thefull-scale mine methane gas detection technology has great significance forensuring the safe production in coal industry, reducing accident, protecting lifeand property losses, using energy and protecting environment.Since the thermal conductivity gas sensor output signal is small andvulnerable to the environmental temperature and humidity and so on, the keytechnology of this project is to study of thermal conductivity gas sensor detectionprinciple and ambient temperature and humidity compensation methods. Thispaper put forward a constant temperature detection method of thermal conductiongas sensor, through analyzing the theory of thermal conduction sensor andmeasurement method. Then this paper analyzed the influence of environmentalhumidity and temperature and established mathematical model, at last putforward a compensation method for the environmental humidity and temperaturethrough combine constant detection and digital compensation, to achievefull-scale methane gas measurements with a single thermal conductivity sensor.According to the design specifications and functional requirements oftransmitter, this paper determines the overall scheme of the design. Thetransmitter hardware is designed using modular processing, the design hasmicrocontroller system circuit module, power module, signal amplifying circuitmodule and signal output circuit module; also finished PCB drawn and debuggedcircuit module and the whole on this basis. Software design includes the mainprogram, temperature and humidity data collection procedures, remote control decoding procedure, calibration procedures, the concentration of data processingprocedures and CAN bus communication procedures, and other functionalmodule design.This paper takes a preliminary test for the impact of ambient temperatureand humidity to the sensors, and conducts a full-scale thermal conductivitymethane transmitter ambient temperature compensation function test, sensorambient humidity drift experiments and sensor humidity compensationexperiments etc.The results indicate that the full-scale methane transmitter meetthe standard requirements of coal mine methane and industrial transmitters andhas a practical value.