Research Of Dual-band Infrared Light Flammable Gas Detector

The flammable gas detector is a safety monitor instrument, which is widely used in the petroleum chemical industry field. It is very meaningful to research on the advanced flammable gas detector. At present, most of the flammable gas detectors are based on the catalytic combustion principle. When the detectors are used to measure the gas of low oxygen environment, or certain background gas which can easily poisoned the catalyze components, they have certain limits. However, the infrared light flammable gas detector is very suitable for the hydrocarbon with stronger absorbing ability to some frequency band infrared light. Compared to the catalytic combustion principle, the infrared light flammable gas detector has some proper merit such as no chemical reaction occurrence, high reliability and stability, and no lower sensitivity when being exposed in the highly concentrated flammable gas. Therefore, in this thesis, from both theoretical and experimental perspectives, thorough analysis and research to the infrared light flammable gas detector is carried on, and the main achievements are as follows:Firstly, the present researching situation and the development tendency of the flammable gas detector in the country and abroad are discussed in this thesis, the characteristics and disadvantages of the flammable gas detector in the present market is analyzed , and a design thought of dual-band infrared light flammable gas detector is offered.Secondly, the system model of the dual-band infrared light flammable gas detector is constructed, and infrared lamp-house, light root system, detectors and the detectors'disposal circuit are designed in detail, the hardware configuration and the function of the dual-band infrared light flammable gas detector are studied. The measure error of the sensor could be restrained by using the differential output way of the measure values.Finally, the detector's design is proposed in this thesis, separately including the lamp-house's preheat interval experiment, the temperature experiment, the gas density detect experiment. The empirical data recorded in detail. The experimental result indicates that (1) the lamp-house's preheat interval about 35 ~ 40 minutes, and the lamp-house is basically stable. (2) The tendency of the referenced channel which goes along with the temperature changing is quite the same with the detective channel. The Least Square method and the MATLAB software simulation are used, the relational curve model between the temperature and the sampling value of the referenced channel and the detective channel are obtained separately, and the referenced channel to compensate the zero drifting of the detective channel is realized. (3) Through building the compensate table about the temperature and the detective channel's change quantity, the detecting density deviation caused by the temperature change is compensated. This thesis's findings have some reference value for improving and enhancing the dual-band infrared light flammable gas detector's performance.