Coal conveying via temperature-measuring optical cable

Distributed optical fiber temperature sensing (DTS) enables real-time, continuous monitoring of coal conveyor belts and coal yards, enhancing safety, efficiency, and predictive maintenance.

Technology Overview

Temperature-measuring optical cables, or fiber optic DTS systems, use the principle of Raman scattering and optical time domain reflectometry (OTDR) to detect temperature changes along the length of the cable. Laser pulses are sent through the fiber, and backscattered light is analyzed to determine the temperature at each point along the cable with high spatial resolution, typically around 1 meter, and temperature accuracy of ±0.1°C to ±1°C . This allows continuous monitoring of critical components such as conveyor rollers, motors, and coal piles.

Installation Methods

Optical fibers can be installed in linear, U-shaped, or circular layouts depending on the application. In coal yards, cables are often arranged along the coal retaining walls at intervals of 1–2 meters to cover the entire area . For conveyor belts, fibers are laid along both sides of the belt, particularly at key points like the head, tail, and bridge sections, with spacing of approximately 1 meter between sensors . The cables are typically armored with metal or flame-retardant thermoplastic oversheaths to withstand mechanical stress, bending, and environmental hazards such as dust, moisture, and corrosive gases .

System Integration

The optical fiber sensing system is connected to a DTS controller and an interrogation system, which transmits data to a host computer or industrial PC. Data can be displayed in real-time, printed, or integrated with a programmable logic controller (PLC) for automated alerts and control actions . Advanced systems can also interface with Ethernet or RS485/232 networks for remote monitoring and cloud-based analytics.

Operational Benefits

1. Early Fire and Overheating Detection: Continuous temperature monitoring allows rapid identification of hotspots, preventing fires and equipment damage .
2. Safety: Reduces the need for personnel to access moving conveyor belts, minimizing risk of injury .
3. Predictive Maintenance: Temperature trends help identify potential failures in rollers, motors, or belt sections before catastrophic breakdowns .
4. Cost Efficiency: Early detection of anomalies reduces downtime and maintenance costs, while optimizing conveyor operation .
5. Environmental Compliance: Accurate temperature data supports reporting and adherence to safety regulations .

Technical Specifications

• Temperature range: Long-term -55°C to 200°C; short-term up to 120°C .
• Fiber type: Single-core or multimode, often metal-armored.
• Bending radius: Minimum 10–20 times the cable outer diameter during installation .
• Response time: 12–40 seconds depending on system configuration.
• Measurement distance: Options from 2 km up to 30 km, with sample intervals of 1 meter .

Applications

• Underground coal mines: Monitoring conveyor belts, rollers, and motors.
• Coal yards: Detecting temperature anomalies in coal piles and retaining walls.
• High-voltage cable monitoring: Integrated systems can also track cable temperature to prevent insulation failure . By implementing temperature-measuring optical cables, coal operations can achieve real-time, distributed monitoring, enhancing safety, operational efficiency, and predictive maintenance capabilities across conveyor and storage systems.