Design and application of coal mine gas early warning system based on sensor network

Aiming at the characteristics of poor gas monitoring effect and difficult early warning, a set of coal mine gas monitoring and early warning system is designed based on sensor network technology. The system uses distributed deployed gas sensor nodes to collect gas concentration data inside the mine in real time, and transmits the data to the ground monitoring center through the ZigBee wireless communication network. After experimental testing, the sampling accuracy of the sensor node is better than ±0.5%LEL, and the repeatability error is less than 1%. The system has designed a gas alarm algorithm based on dynamic thresholds, which can adaptively adjust the alarm threshold according to the changing trend of gas concentration. While ensuring the timeliness of alarms, the false alarm rate is reduced by more than 60%. When the gas concentration exceeds the limit, the system can issue an alarm within 1 second, with an accuracy of more than 98%. Through pilot applications in Qianjiaying Coal Mine of Kailuan（Group） in Hebei Province, it has been confirmed that the system can conduct all-round real-time monitoring of mine gas, and the average lead time of gas accident warnings has been increased to more than 30 minutes, effectively improving the safety level of coal mine production.