| In the process of coal mining,a variety of harmful gases are produced,such as CO,CH4,H2,CO2,which often lead to coal miners poisoning,even fire,gas explosion and other accidents,seriously endangering the lives and property safety of coal miners.In order to provide a safe and reliable working environment for coal miners and reduce the occurrence of coal mine accidents,it is necessary to detect the mixed gas under the mine online.In this paper,an on-line detection instrument for mixed gas in coal mine is designed,which can realize the real-time on-line detection of gas concentration information in many places in coal mine.Through the construction of sensor network,Detection of gas concentration in high risk area of coal mine.Four kinds of gas sensors are used to detect the concentration of CO,CH4,H2 and CO2 respectively.The detection signal is sent to STM32 after A/D conversion and digital filtering processing.The detection result can be displayed on the spot by LCD.The detection equipment has self inspection and over limit alarm functions.The MQ7 semiconductor sensor used to detect CO gas concentration is greatly affected by the change of ambient temperature and humidity and H2 concentration.In this paper,a compensation algorithm based on the least square method is proposed,Calibrate and compensate MQ7 and MQ8 sensors,which reduces the impact of temperature and humidity and H2 concentration change on MQ7 measurement results and improves the measurement accuracy of MQ7.The experimental results show that the system can meet the requirements of the regulations in terms of real-time performance and accuracy.The MQ7 sensor temperature and humidity and hydrogen compensation algorithm effectively reduce the interference of the environment temperature and humidity and the change of H2 concentration on the CO gas measurement results.Due to the complex underground environment of coal mine,it is difficult to check the detection results on site.This design also carries WiFi module,which can realize the data interaction from equipment to cloud and cloud to mobile by using communication module.At the same time,the mobile App is developed.The App can read the gas concentration data of the detection equipment and display it dynamically in real time,and has the alarm function,so that the detection personnel can view the underground environment information of the coal mine remotely and in real time.It also provides the network supervision scheme for the relevant national regulatory departments,which can discover the potential safety hazards in a more timely manner and reduce the loss caused by the accident. |
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