The Design Of An Integrated System For Detecting Effluvial Sulfur-Based Gases

The sulfur-based gases coming from industrial manufacturing process is not only odorous,but also a great threat to human health.In traditional testing ways,we have to bring samples back to laboratory to analyse what the components are in the air.The way takes so much time that it always makes inconvenience.In this case,it becomes a big problem how to analyze the mixed gas on site.Based on this background,some scholars have proposed to combine gas chromatography which has high separation characteristics with surface acoustic wave sensor which has high sensitivity to form a GC/SAW system for on-site detection.Based on our team's existing research results of gas chromatography and SAW sensor,this paper studied how to construct GC/SAW cascade system to separate and detect four kinds of sulfur-based malodorous gases,such as methyl mercaptan,methyl sulfide,carbon disulfide and dimethyl disulfide.Then base on this part,we designed PIC program to convert electrical signal into a digital signal and compiled PC software to handle the datas from PIC.1.By optimizing the air jet process with the chloroform and SC-F101 solution,this paper has improved the SAW sensor's detection performance.Experiments with the chromatograph confirmed that the SAW sensor has a good response to 10.7ng methyl mercaptan gas flowing out at the end of the column.This paper has compared the difference of the SAW sensor's signals in two different gas purging modes.2.Through the study of the working conditions of the enrichment device and gas chromatograph by combining the enrichment device,gas chromatography and SAW sensor together,the four sulfur-based mixed gases were separated and detected in this paper.Experiments show the conclusion that the enrichment of the enrichment device is more than 5000 ng which indicate that the separation and detection module can separate and detect four sulfur-based mixed gases by using the enrichment device theoretically.And the separation and detection module has been verified by experiments.3.This paper has designed the PIC data acquisition module and the data receiving and processing module formed by PC software to realize real-time monitoring of SAW sensor's test signal.By increasing the sampling frequency to 5Hz,this paper solves the problem of signal distortion caused by the traditional sampling method.According to the actual needs,this paper has designed PIC timing acquisition,handshake recognition and other functions.Finally,by combining the separation and detection module formed by enrichment device,the column,the SAW sensor,the PIC data acquisition module and the data receiving and processing module together,this paper has built a simple GC / SAW detection system that realizes the separation and detection of the four sulfur-based mixed gases.The research results can provide the experimental basis for the portable GC / SAW detection system.The research of the data acquisition and processing module lays the foundation for the spectral peak recognition of the signal.