Carbon Monoxide Detection Technology Based On Photoacoustic Spectroscopy Research And Implementation

Carbon monoxide gas is one of the major pollutants in some chemical parks,hazardous chemicals warehouses,and closed cabins.Carbon monoxide is a colorless and odorless flammable and explosive dangerous goods under normal temperature and pressure.The rapid and real-time detection of carbon monoxide gas is of great significance in industrial production.Compared with traditional gas detection methods,photoacoustic spectroscopy gas detection technology has very significant advantages and has received increasing attention.Photoacoustic spectroscopy gas detection technology is a kind of gas detection technology based on photoacoustic effect.It has the characteristics of fast response,good selectivity and large dynamic range.This article takes the actual application of engineering as a starting point,studies the carbon monoxide detection technology based on photoacoustic spectroscopy,designs the optical path and circuit,and completes the production of a prototype.This paper first introduces the technical background and research status of photoacoustic spectroscopy gas detection,and then analyzes the theoretical basis of photoacoustic spectroscopy detection technology.In combination with the HITRAN2016 database,the absorption spectrum of carbon monoxide gas was analyzed and determined.The vertical cavity surface emitting laser is selected as the excitation light source,and the laser is modulated by a combination of triangular wave scanning and sine wave modulation,and the electret microphone is used to convert the photoacoustic signal into an electric signal.The design of the photoacoustic cell was discussed in this paper.A first-order vertical resonant photoacoustic cell was designed and designed.The bandpass filter circuit,lock-in amplifier circuit,phase-shift circuit,low-pass filter and analog-digital conversion circuit were designed.Combining with the embedded technology,taking the STM32 microcontroller as the core,the FreeRTOS real-time operating system is used to schedule the system peripherals and resources to measure the concentration of carbon monoxide at different concentrations from 100 to 1000 ppm.At the end of the article,the prototype was calibrated and tested.The experimental results were analyzed and the improvement measures were proposed.The test results show that there is a good linear relationship between the amplitude of the photoacoustic signal and the concentration of carbon monoxide gas,which verifies the feasibility of the carbon monoxide detection technology based on photoacoustic spectroscopy.The system prototype is stable in operation and can be applied to industrial sites to detect the concentration of carbon monoxide in real time.By setting the alarm point,when the carbon monoxide exceeds the alarm concentration,it can be automatically alarmed.