Coal Mine Belt Conveyor Monitoring System

The safety and reliability of the belt conveyor production and transportation system directly impact the economic benefits of the mine. Centralized coal flow control, surface dispatch monitoring, video surveillance, and other aspects are interconnected and controlled, forming the foundation for automation in coal mining, enabling unmanned operations. High production, high quality, safety, energy-saving, and labor-saving are essential for reducing the number of operators, ultimately lowering costs, improving labor productivity, and maximizing profits. This is the cornerstone for coal enterprises to survive in future competition. Achieving efficiency with fewer workers, lowering costs, improving labor productivity, and implementing centralized monitoring to ensure comprehensive protection and remote control are necessary.

Based on this, our company has independently developed a Coal Mine Belt Conveyor Monitoring System, which can protect, control, facilitate communication along the line, detect faults, display Chinese characters and graphics, and provide voice alarm communication for both fixed and temporary belt conveyors.

The system integrates Siemens S7 series Programmable Logic Controllers (PLC) and embedded technology, replacing the traditional Single-Chip microcontroller system. This overcomes the drawbacks of the microcontroller system, such as complex software design and poor anti-interference capability. The human-machine interface of the system is intuitive and visually displays the operational status and various data parameters of the belt conveyor.

The system supports data transmission methods such as Ethernet, RS485, PROFIBUS, and CAN fieldbus, enabling communication with external computers or devices using RS485, PROFIBUS, and other communication protocols. It also facilitates centralized monitoring of multiple belt conveyors. The system has an Ethernet interface, allowing data to be uploaded to the surface central control dispatch center via the coal mine's ring network for centralized monitoring. Communication between Loudspeaking Telephone is realized via the CAN bus, and the entire system uses a "quick-plug" connection method, which is easy to install and flexible.

1.Control Function
The system can realize both single-machine control and centralized control for multiple belt conveyors. The belt conveyors include:Upward Belt Conveyors, Downward Belt Conveyors, and Flat Tunnel Belt Conveyors.

2.Control Modes

The system offers multiple control modes, including remote control, centralized control, local control, and maintenance control, with reliable interlocking functions between different modes.

(1)Remote Control Mode
Remote control is managed by the surface dispatch center's upper-level software platform, where the "Start All" and "Stop All" buttons control the sequential start and stop of the belt conveyors.
There is a logical and interlocking relationship between the different belts: the conveyors start against the coal flow direction and stop with the coal flow direction.

(2)Centralized Control Mode
The centralized control main station's control panel includes "Start All" and "Stop All" buttons to implement the sequential start and stop control of the belt conveyors.
The startup and stop delays for each belt conveyor can be set via the parameter settings screen.

(3)Local Control Mode
Operators can start and stop each device locally through the control main station and control sub-stations. The system includes an interlocking function: if the upstream device is not started, the downstream device cannot be started. If the upstream device stops, the downstream device will immediately stop.
Each belt conveyor in the centralized control system has a reliable interlocking relationship.

(4)Maintenance Control Mode
Operators can start and stop each device locally through the control main station and control sub-stations without interlocking functions.

3. Startup Warning Function
The belt conveyor startup is equipped with a startup warning voice alert, and the warning time can be adjusted.

4. Voice Broadcasting System

The system's main unit works in conjunction with Loudspeaking Telephone to provide functions such as dialing, communication, and voice alarms along the belt conveyor line, with clear and loud audio. Belt conveyor inspection personnel can communicate with on-site workers at any time, facilitating belt maintenance and coordination.

The system allows for the installation of one Loudspeaking Telephone every 100 meters along the belt conveyor line. The Loudspeaking Telephone are equipped with an emergency stop lockout function. If the surface monitoring center is equipped with voice Loudspeaking Telephone control software, remote voice communication along the belt conveyor line can also be realized. Communication between the surface monitoring center and the belt conveyor system is achieved through Ethernet, enabling remote voice communication.

5.Display Function

The control main station is equipped with a 15-inch color LCD display, and the sub-stations are equipped with 7-inch color LCD displays. These displays show the operational status of each conveyor in graphical, animated, and Chinese character formats. Additionally, they can display belt protection alarm information and include a history alarm query function.

6.Belt Conveyor Protection Function

When a protection alarm occurs, the system provides detailed alarm notification features.

●Real-time Speed Detection: The belt conveyor is equipped with a real-time speed detection function.

●Sensors for Protection: The belt is equipped with sensors for coal piling, misalignment, emergency stop, smoke, temperature, vibration, tearing, and speed. These sensors monitor and protect the operational condition of the belt, and can trigger alarms to stop the system.

At the control main station, individual protections for each conveyor can be selectively disabled using the keyboard, depending on the situation. When protection is disabled, an alarm will be triggered but the system will not stop.

●Pull-wire Emergency Stop Lockout Switches: These are installed along the belt conveyor line with an address encoding function. When an emergency stop occurs, the failure location of the emergency stop sensor will be displayed directly on the monitor, and a voice alarm will announce the failure location, making it easier to troubleshoot.

●Misalignment and Tearing Sensors: These sensors can be connected to the Loudspeaking Telephone system along the line with address encoding. When a protection action occurs, the fault location of the misalignment or tearing sensor will be displayed directly on the monitor, and a voice alarm will announce the fault location, simplifying fault resolution.

7.Password Protection Function

Before parameter settings can be made at the control main station, the user must log in. This effectively prevents unauthorized personnel from modifying parameters, ensuring that only qualified individuals can make changes.

8.Historical Data Query Function

Both the system monitoring upper-level computer and the PLC electric control host support querying data reports, including historical fault records, equipment operation records, equipment running records, and equipment operation time. The upper-level computer system also supports one-click export and printing functions. The system is capable of storing data for at least one year.

9.Communication Function

The PLC system is equipped with an RS485 communication module and a standard TCP/IP Ethernet interface, making it easy to connect with intelligent power supply devices or other on-site intelligent equipment for data reading and writing.

Communication between the PLC system and the surface upper-level computer is achieved via fiber optic transmission.

The entire network adopts open Ethernet standard technology commonly used in industrial automation. Devices can be connected from the field level to the management level, enabling communication across the system and supporting engineering and configuration across the mine, with full support for IT standards at all levels. This improves product usability and system maintainability. The system uses real-time Ethernet communication, with data response times of less than 150 milliseconds.

10.Video Surveillance System

The video surveillance system collects on-site image information using video cameras. The collected data is transmitted via fiber optic communication to the surface monitoring center, allowing for intuitive and convenient remote monitoring of the belt conveyor's operational status. This further enhances the system's reliability and safety.

The cameras are connected to the mine's ring network switch using fiber optic cascading, directly uploading the video feed to the surface monitoring center.

Main Functions

(1) Information Collection: The image signals captured by the cameras are transmitted in real-time to the display screen.

(2) Video Sub-control Management: Allows simultaneous monitoring of multiple different image signals, enabling remote monitoring, remote access, alarm linkage, and other functionalities.

(3) Monitoring Function: Any video signal can be monitored through the display screen.

(4) Playback Function: Real-time queries and playback of the images stored on the hard disk recorder are supported.

(5) Recording Function: The hard disk recorder supports real-time and scheduled recording storage.

(6) Switching Function: The system can automatically cycle through the set images based on a time period for regular scanning.

(7) Preview Function: Users can directly access IP cameras or video servers via an IE previewer.

(8) Video File Query Function: All video files from the cameras can be queried based on time, alarm records, and other parameters.

11. Upper-level Computer Remote Monitoring System

The unmanned remote monitoring station for the belt conveyor system is set up in the dispatch center, equipped

with high-performance industrial computers, monitors, upper-level computer software, configuration software, audio systems, gigabit switches, and other equipment. The industrial computer is installed with the upper-level configuration software, which allows for real-time display of the belt conveyor system's operational parameters, such as temperature, smoke, coal piling, speed, emergency stop, misalignment, tearing, motor temperature, vibration, and other parameters.

The system also displays the operational status of equipment, fault information, and video linkage. The upper-level computer enables functions such as display, data storage, remote operation, and communication with underground equipment, including dialing, Loudspeaking Telephone, and music playback.

1.Control Equipment

(1)TH18 Mining Intrinsically Safe Control Panel: This panel offers centralized control and video display/storage functions. It features dual-screen display capability and a stainless steel housing. The TH12 mining intrinsically safe control panel is equipped with a 15-inch LCD control screen, displaying the operational status and protection information of all belts in the system using graphics, animations, and text. The panel also includes a hard disk recorder, optical terminal, and a 21-inch monitor for video storage and real-time display. It is equipped with two metal mice for easy operation. The control main station provides dialing, communication, and voice alarm functions.

(2) KXJ127(A) Mining Explosion-proof and Intrinsically Safe Programmable Control Box: This control box utilizes advanced technologies including the German Siemens S7 series PLC, embedded technology, voice broadcasting, network communication, and computer technology. It integrates these high-tech features into a comprehensive protection and automation control system. The control box is equipped with Ethernet, RS485 fieldbus, and CAN fieldbus data transmission interfaces, and is used in conjunction with the control panel.

(3) KTC169.1 Mining Explosion-proof and Intrinsically Safe Communication Controller: This controller is composed of Siemens' latest S7-200 Smart series PLC, digital expansion modules, communication modules, and other components. It features a 7-inch LCD display that shows the operational status of the equipment, protection information, and more. The system also supports functions such as dialing, communication, and voice alarms.

(4) KJS12 Mining Intrinsically Safe Input/Output Module: The KJS12 module is used in conjunction with control sub-stations or control boxes. It supports 16 thermocouple signal inputs and 16 analog signal inputs, which are used to collect data such as the motor's three-phase winding temperature, front and rear bearing temperatures, gearbox temperature, and motor/gearbox vibration. The module communicates with electrical control equipment via RS485 and supports the standard Modbus protocol.

2. Protection Sensors 

(1)Loudspeaking Telephone System: The KTK18-ZH Mining Intrinsically Safe Pull-wire Emergency Stop Loudspeaking Telephone is primarily used in areas with explosive gas and coal dust hazards, such as inclined shafts, tunnels, belt faces, and fully mechanized mining faces in coal mines. It enables dialing and communication functions along the conveyor line. The system can emit visual and audio alarm signals while receiving external signals for remote audio playback. When connected to the belt conveyor protection control host, it enables emergency stop lockout along the conveyor line.
Typically, one intrinsically safe pull-wire emergency stop Loudspeaking Telephone is installed every 100 meters along the belt conveyor line. Each Loudspeaking Telephone has four over-current input interfaces that allow local connection to misalignment, tearing, or other sensors. The Loudspeaking Telephone also features address coding, allowing fault locations to be displayed directly on the belt conveyor protection control host's screen, and the fault location's voice alarm information is provided, which facilitates quick troubleshooting.

(2) Stop Lockout Switch: The KHJ24A Mining Intrinsically Safe Bidirectional Emergency Stop Lockout Switch is a mining intrinsically safe electrical device designed for use in coal mine environments where there is a risk of gas or coal dust explosions. It is used for pull-wire emergency lockout protection along the belt conveyor line.
The switch is equipped with an internal fault location identification module, which allows the belt conveyor protection control system to identify the fault location through this device.

 

(3) Speed Sensor: The GSG5 Mining Intrinsically Safe Speed Sensor converts the linear speed of the belt conveyor into an analog signal. After processing by the main control unit, the corresponding conveyor speed is displayed. The sensor is installed above the lower belt of the head pulley and measures the data via rollers. The system displays the belt's operational speed on the belt conveyor protection control host.
The sensor allows for the setting of upper and lower speed limits and provides protection for both overspeed and underspeed conditions. Speed variations caused by normal starting and stopping do not trigger the protection, and the speed delay protection time can be configured.

(4)Temperature Sensor:
●The GWK42 Mining Intrinsically Safe Temperature Sensor is designed for use in coal mine environments containing gas, coal dust, and explosive gases. It is used in conjunction with the belt conveyor protection control host. The sensor monitors the temperature of the main drive drum and belt of the belt conveyor. If the temperature exceeds the preset limit due to friction between the drum and the belt, it will trigger an alarm and stop the conveyor's operation to prevent overheating and potential hazards. It can also be used in non-explosive areas on the surface where belt conveyors are present.

●The GWH100 Mining Intrinsically Safe Infrared Temperature Sensor is designed for use in coal mine environments with explosive gases like methane and coal dust. It monitors the temperature of key components such as the conveyor belt's rollers, reducers, high-speed shafts, motor housings, and bearing seats on the drive rollers. The sensor features a built-in digital temperature display and outputs a 4-20mA signal, which is transmitted to the belt conveyor protection control host. The corresponding temperature values are displayed, providing a real-time, intuitive view of the temperature of the shafts or equipment being monitored.

(5) Smoke Sensor:
●The GQQ5 Mining Intrinsically Safe Smoke Sensor is designed for use in coal mine environments containing gases such as methane, coal dust, and other explosive gases. It is used to detect smoke generated by the belt conveyor's belt due to frictional heating or other causes. The sensor is typically installed 5-15 meters downstream of the conveyor drive location to monitor for smoke. If smoke is detected, it triggers an alarm and halts the conveyor's operation to prevent further risk.

●The GQQ5(A) Mining Intrinsically Safe Smoke Sensor (with a stainless steel housing) is designed for use in coal mine environments with methane, coal dust, and explosive gases. It is integrated into the belt protection system to detect smoke generated by the belt conveyor's belt due to frictional heating or other causes. This sensor can also be used in surface, non-explosive areas where smoke monitoring is required.

(6) Coal Pile Sensor: The GUD2 Mining Intrinsically Safe Coal Pile Sensor is designed for use in hazardous areas with explosive methane gas mixtures, as well as in open-pit coal mines, coal preparation plants, and similar environments. It provides coal level protection for the belt conveyor protection control system. The sensor is installed vertically above the coal bin or at the coal drop point of the conveyor head. When the coal pile reaches a certain height, the resistance between the coal electrode and the ground becomes less than 1.5 MΩ. This triggers the relay to close the normally open contacts, activating the control circuit of the main unit and sending a fault signal to stop the system, thus protecting against coal pile buildup. After the fault is cleared, the sensor automatically resumes normal operation.

(7)Misalignment Sensor:
●The GEJ30 Mining Intrinsically Safe Misalignment Sensor is an intrinsically safe electrical device used to detect misalignment protection for belt conveyors. When the conveyor belt becomes misaligned, the belt forces the roller shaft to shift. If the swing angle of the misalignment sensor's roller shaft reaches ≥30º, the microswitch is activated, sending a stop signal. This cuts off the conveyor control circuit, halting the system, or sends a misalignment fault signal to the monitoring station. Once the fault is cleared, the roller shaft returns to its normal operating position due to the restoring force of the spring.

●GEJ20/35(A) Mining Intrinsically Safe Misalignment Sensor (Dual-Level Misalignment: Level 1 Alarm, Level 2 Stop) This sensor is designed for use in coal mine environments, open-pit coal mines, coal preparation plants, and similar workplaces, to protect the belt conveyor from misalignment. When the conveyor belt misaligns, it forces the roller shaft to shift. If the swing angle of the misalignment sensor's roller shaft reaches a specific value, the microswitch is activated, sending a stop signal that cuts off the conveyor control circuit, halting the system, or sends a misalignment fault signal to the monitoring station. The sensor has two action angles: Level 1: 20° ± 5° and Level 2: 35° ± 3°. Once the fault is cleared, the roller shaft returns to its normal operating position due to the restoring force of the spring. The reset angle of the sensor is 10° ± 3°. The limit angle for the probe's rotation is ≥60°, and the probe's activation force ranges from 10 to 30 N.

(8)Tear Sensor:
●The GVY25 Mining Intrinsically Safe Tear Sensor is designed for use in coal mine environments with explosive gases like methane and coal dust, as well as in non-explosive areas where belt conveyors are present. It provides protection for the conveyor belt against longitudinal tears. During normal operation of the conveyor, the sensor is in detection mode. If no tear is detected, the sensor outputs a resistance value of ≥1MΩ. However, if the conveyor belt tears, causing coal to fall and land on the sensor, the sensor's output resistance drops to ≤500Ω. This triggers the conveyor protection control system, which then activates an alarm and stops the conveyor to prevent further damage.

●The GVH3 Mining Intrinsically Safe Tear Sensor (Infrared) is designed for use in hazardous coal mine environments with explosive gases such as methane and coal dust, as well as in non-explosive areas where belt conveyors are in use. It provides protection for the conveyor belt against longitudinal tears. When the conveyor belt experiences a longitudinal tear, the coal on the coal-support plate exceeds a height of 30mm, causing the tear sensor's receiver to activate. The relay contacts K1 and K2 on the receiver close, sending a fault signal to the conveyor protection control system. After the fault is resolved, the relay contacts K1 and K2 on the receiver open, and the sensor returns to its normal operating state. The sensor's operational status can be easily checked by the red light indicator on the receiver: Flashing red light indicates normal operation. Solid red light indicates a tear fault has occurred.

(9) Tension Sensor: The GAD200 Tension Sensor is designed for use in coal mine environments with hazardous gas mixtures, such as methane and coal dust, to monitor the tension of the conveyor belt. It helps prevent the belt from becoming too tight or too loose, ensuring the proper functioning of the conveyor system. This sensor is a side-pressure type stainless steel tension sensor, and the wiring is connected via a junction box, making it flexible and convenient for installation. The signal collection distance is not limited, allowing the sensor to be used in various positions along the belt conveyor for optimal tension monitoring.

(10) Automatic Sprinkler System:
●The DFB20/7 Mining Explosion-Proof Electric Ball Valve is designed for coal mine environments with explosive hazards, such as methane and coal dust, as well as areas with poor water quality or varying water pressure. It is used for automatic dust suppression and fire extinguishing control systems, managing the automatic opening and closing of the water flow. This electric ball valve can be used independently or integrated with other monitoring systems. The valve operates by rotating a ball to open or close the water path. It is suitable for a wide range of water supply pressures, is resistant to sand and dirty water, has a large water passage, and provides stable and reliable operation with short power-on times. The valve is highly durable, has strong anti-interference capabilities, and offers high water flow capacity. It provides a signal output when fully open or closed.

●DFB20/6 Mining Explosion-Proof Solenoid Valve:
The DFB20/6 Mining Explosion-Proof Solenoid Valve is designed for hazardous environments in coal mines where coal dust and explosive gases are present. It is primarily used for dust suppression and dust removal purposes. The solenoid valve operates based on the principle of an alternating current electromagnet and is designed in accordance with national and industry standards. It serves as an automatic control valve for liquids, gases, and other pipelines. This solenoid valve is a fundamental device for achieving pipeline automation in mining operations.

(11)Mine-use Camera:
●KBA127 Mining Explosion-Proof Camera (with Fiber Optic and Network Interface):
The KBA127 Mining Explosion-Proof Camera is a next-generation explosion-proof monitoring device, featuring advanced H.265 intelligent encoding technology and a 1/3-inch 1-megapixel high-definition camera. Its quality and performance are among the best in its category both domestically and internationally. This integrated design camera offers high resolution, low-light capability, spark-proof features, waterproof and dustproof construction, compact size, lightweight, flexible configuration, minimal transmission loss, long transmission distance, and easy installation. Additionally, it includes functions like strong light suppression and the ability to switch from color to black-and-white display for better visibility in challenging environments.

●KBA12H Mining Intrinsically Safe Infrared Camera:
The KBA12H Mining Intrinsically Safe Infrared Camera is designed for underground video surveillance in coal mines. It features an Ethernet optical signal output interface. External light enters the lens through a glass window, is focused onto the CCD chip, and converted into Ethernet optical signals for transmission. The camera can operate in extremely low-light conditions, with a minimum illuminance of 0.05Lux, allowing clear visibility of objects. The collected real-time images are converted into Ethernet optical signals for output. It operates with a DC 12V power supply, and is equipped with 2 SC-type interfaces for TCP/IP Ethernet optical signal transmission, making it suitable for secure, long-distance video surveillance in hazardous environments.

●KBA127(A) Mining Explosion-Proof PTZ Camera:
The KBA127(A) Mining Explosion-Proof PTZ Camera uses a variable zoom CCD solid-state imaging device. It supports Ethernet TCP/IP protocol for remote control of the pan-tilt (PTZ) rotation and adjustments to the lens aperture and focal length. The camera features an auxiliary light source, ensuring high clarity even in low-light conditions, and offers precise control of the PTZ for optimal surveillance flexibility. It operates with a rated voltage of AC 127V and is equipped with 1 SC-type interface for TCP/IP optical signal transmission using single-mode fiber.

(12) Vibration Sensor: The GBD20 mining intrinsically safe vibration sensor is an electric device designed for essential safety in mines, providing a basis for monitoring the operational status of coal mining equipment, analyzing failure causes, and formulating maintenance strategies. During vibration measurement, the sensor is fixed to the object being measured. When the object vibrates, the sensor casing vibrates along with it. The piezoelectric crystal in the accelerometer generates a charge under the inertia force of the mass block, and the output charge is proportional to the vibration acceleration. An charge amplifier adjusts the accelerometer's output voltage to be proportional to the input charge, and a (4–20) mA current loop converts this voltage into a corresponding current signal output.

(13) Level Sensor: The GUL30, GUL50, GUL70 mining intrinsically safe radar level sensors are suitable for coal mine environments prone to methane gas and coal dust explosions. These sensors feature innovative design, reliable performance, and easy installation and use. The sensor antenna emits narrow radar wave pulses that are transmitted outward through the antenna. When the radar waves contact the surface of the medium being measured, the signal is reflected back, received by the antenna system, and transmitted to the electronic circuitry, which converts the time difference into distance.