Research On A Real Time Space Methane Detection System

Methane, a colorless and odorless gas, is the major constituent of biogas, natural gas, and so on. It behaves as the main gas-fuel and an important chemical material in the field of civilian use and industry. It is also one of the main intermediate products in the process of producing petrochemicals. However, Methane gas is so inflammable and explosive that the accurate and fast detection of methane together with an early alert have the great importance to protect the safety of production and life. Besides, atmospheric methane is a greenhouse gas, which contributes about 20 times more than the well-known CO2 to the global warming. Moreover, to accurately detect the methane content near the ground space is the foundation of analyzing the potential methane source. Therefore, it is very necessary to research on the methane content detecting in space.Firstly, this paper studies the principle and characteristics of commonly used gas detection technology. Here mainly consists of two parts: the non-optical gas detection technology, including: the ultrasonic gas detection, the electrochemical detection, the semiconductor gas detection, the thermal conductivity gas detection, the catalytic combustion detection, the gas chromatography analysis and so on; the optical gas detection technology, including: the gas detection based on coherent light interference technology, the gas absorption spectrum detection and so on. From the comparison, we find that the gas absorption spectrum detection technology has excellent selectivity, high sensitivity, fast response and less influence on gas, so it is an ideal choice for space methane detection.Secondly, by starting with the molecular absorption spectrum theory and employing the mechanism of molecular absorption spectrum, the Lambert-Beer’s law and the method of spectral absorption gas detection, we chose the 1653.72 nm methane absorption lines from HITRAN data base and confirm the line parameters for this work. Based on the theoretical study, a three-dimensional grid of methane detection method is also designed. By using this method we can not only achieve the accurate detection and locate methane gas in space on real time, but also reduce the number of sensor as well as finding the leaking position when the leakage occurs. Thus it has much significance to the protection of safety production and life.Finally, the important devices in this system are selected and the hardware circuit is designed, including: the laser driver circuit, the triangular wave circuit, the preamplifier circuit and so on. In the end of this paper, the research plan is discussed.