Study And Design Of Methane Detecting System Based On LabVIEW

The detecting of the concentration of methane has great significance in industrialproduction, the life’s safety and the other fields. But so far, as the underground gasdetection system is not perfect, there are many outbreak of mine explosion accidentsevery year in our country. And about half of the people’s death in mine disaster iscaused by gas explosion accident. In addition, with the using of natural gas isincreasing day by day, the gas leakage accident occurs frequently, too. So thedevelopment of the effective methane detection instrument is imminent. As the sensorbased on infrared absorption principle has the advantages of high sensitivity, goodselectivity and high resolution, the infrared detection method has become one of themain gas detection methods in all the gas detection methods. LabVIEW is a graphicalprogramming software launched by NI. It can complete the processing of complexsignal and huge scale of data. It has been wild used in aircraft engineering, industrial,scientific research and so on. This paper is a continue research of a National “863”plan.This paper built a kind human-computer interface and intelligent methanedetector. It is a virtual instrument based on infrared absorption principle and the dataprocessing ability of the PC. This paper contains the design of the hardware and thesoftware. The hardware part contains the pre-amplifier, the main amplifier, the drivingcircuit, the power circuit etc. The software part contains the signal extraction, theseparation, the filtering, the parameters extraction, the storage, etc.The sensor chosen is based on infrared absorption principle and designedby a company from British named E2V. This kind of sensor has two outputs,one of it is a signal which is related to the gas concentration named detectedchannel, the other one is a signal which is named the reference channel has n-othing to do with the gas concentration, it is mainly used to eliminate the co-mmon-mode noise. The signal from these two ways is sent to a simple circuit for processing, after this they are passed to PCI6221by CB-68LP. At last,the signal is passed to LabVIEW to complete the final processing.The detection limit of this system is100ppm. The sensitivity in the lowerconcentration is100ppm.