Belt conveyor is a type of belt conveyor, especially when running on a pier. Due to the large amount of coal dust generated, high temperatures or encountering open flames, it can cause coal dust combustion, posing a threat to the production of coal preparation plants. However, in practice, due to the long transportation distance of the belt conveyor on the wharf, it is difficult to monitor the operating temperature of the belt. Therefore, there is an urgent need for a monitoring and early warning system that can achieve efficient and reliable early warning monitoring of the operating temperature of the belt, and avoid adverse effects on the production of the coal preparation plant due to transportation faults of the belt conveyor.
The fiber optic temperature measurement system can achieve large-scale temperature measurement, which cannot be achieved by traditional temperature sensors. At the same time, it has advantages such as strong anti-interference, high temperature resistance, and convenient construction. Therefore, the fiber optic temperature measurement and warning system can be applied to the belt conveyor of the coal preparation plant, achieving real-time and fully distributed temperature measurement of the belt conveyor, and improving the safety assurance ability of the coal preparation plant operation.
The implementation of fiber optic temperature monitoring mainly utilizes the temperature characteristics of fiber optic cables. By processing the temperature information collected by the fiber optic cables on the monitoring site and comparing the processed temperature with the actual design alarm temperature, the on-site fire alarm prediction function is achieved.
Working principle of distributed fiber optic temperature measurement
When light waves propagate in optical fibers, when there is a temperature change at a certain point in the fiber, backscattered light is generated. By calculating the transmission time of backscattered light, the specific location of the temperature change point can be obtained, thereby achieving the positioning of temperature anomalies. Based on the differences in the principles of reflected light signals measured, fiber optic temperature measurement systems can be specifically divided into Rayleigh scattering systems, Manla scattering systems, and Brillouin scattering systems. When laser propagates inside the fiber, the above three different scattering phenomena appear on the surface of the fiber. Among them, Rayleigh scattering has poor sensitivity to temperature increase, while Manla scattering and Brillouin scattering are more sensitive to temperature increase. Therefore, Manla scattering and Brillouin scattering can be used to measure temperature changes. According to the principle of spectrum analysis, the spectrum between Rayleigh scattering and Brillouin scattering is relatively close, and it is difficult to effectively distinguish between the two types of scattering using filters. Therefore, Raman scattering is most widely used in fiber optic temperature measurement systems.
The fiber optic temperature measurement system used in coal plants mainly consists of detection optical cables and fiber optic hosts. The detection optical cable is mainly used to measure the temperature along the belt conveyor line; The fiber optic host is used to process the obtained fiber optic signals, issue alarm messages, and set relevant parameters. The fiber optic host can be connected to the fire alarm system of the monitoring center through CAN, RS485/232, and Ethernet interfaces to build a complete fire warning and alarm system.
It has been running smoothly on the belt conveyor of the coal preparation plant for 13 months, with high temperature monitoring accuracy, fully reflecting the superiority of temperature measurement, controlling the hidden dangers of accidents in the bud, providing practical guarantees for safe and stable production of the coal preparation plant, and improving scientific judgment ability. By installing a temperature measurement monitoring and early warning system on the belt conveyor transportation system of the coal preparation plant, it is possible to prevent nearby coal dust fires caused by mechanical scraping faults causing stoppage of rollers, rollers, etc., and friction with the tape resulting in high temperatures, as well as nearby combustible material fires caused by drive motor faults. This effectively avoids belt conveyor faults causing fires or human factors causing fires near the belt conveyor. There are still 2 temperature measurement channels reserved in the coal preparation plant, which can be used for fiber optic temperature measurement monitoring systems in other areas of belt conveyors to build a more comprehensive safety assurance capability. The successful application of the fiber optic temperature measurement monitoring and early warning system in this coal preparation plant provides certain reference experience for monitoring the operating temperature of belt conveyors in other coal preparation plants. The fiber optic arrangement method for simultaneously measuring the temperature of tape and drive motor has significant practical and promotional value.