Research And Design Of Intelligent Methane Concentration Monitoring System Based On NB-IoT

With the development and progress of modern science and technology,the era of Smart City and big data has come,and wireless communication will realize the connection of all things.The traditional methane concentration monitoring has the disadvantages of low accuracy,short life,poor real-time performance,high operation and maintenance costs,and poor system scalability and portability.In view of this,this paper combines the emerging Internet of Things communication technology NB-IoT(Narrowband Internet of Things),and proposes an intelligent monitoring and analysis system for methane concentration based on NB-IoT,to achieve real-time online monitoring and analysis of methane gas concentration.The main research work of this paper is as follows:(1)Based on NDIR(Non Dispersive Infrared)Technology,a dual-channel detection model is used to design the optical system of the methane gas sensor,and a diffuse reflection type gas chamber structure is proposed.The best design scheme of the gas chamber is obtained with the optical simulation software Tracepro being used to simulate and optimize,which realizes the miniaturization of the sensor optical system,and improves the detection accuracy and stability of the system.(2)Based on the modular design idea,the hardware circuit of the detection system and the optical system is modularized,including the core control module,methane concentration detection module,NB wireless transmission module,GPS positioning module and related peripheral circuit parts..which solves the problems of low monitoring accuracy and poor system stability of the methane monitoring system,and realizes the integration,miniaturization and intelligent design of the sensor.(3)Based on the IoT cloud platform and wireless transmission theory,the software of the system is divided into four parts: perception recognition layer,network construction layer,management service layer and comprehensive application layer by using layered architecture idea,and is modularly designed.It solves the problems of unstable data transmission of the methane monitoring system and the limited transmission capacity of the network.And realizes the real-time display of methane monitoring data and geographic location information,command issuance control,historical data viewing,and manual alarms.(4)Concentration calibration and performance testing are carried out on the designed monitoring system.During the calibration,the L-M(Levenberg-Marquardt)algorithm is used to study the parameter identification of the sensor concentration calibration model,which effectively improves the accuracy of the calibration model.After the calibration is completed,an experimental study on the measurement characteristics of the system such as accuracy,repeatability,and stability is carried out.The experimental results show that the sensor monitoring system has good accuracy and precision retention in the concentration range of 0-5%.