0 Introduction
With the increasing service life of Daizhuang Coal Mine and the further expansion of mining areas, the main underground conveyor belts and conveyor belts in each mining area need to be extended or relayed. Furthermore, coal transfer is primarily done directly from the mining area conveyor belts to the main conveyor belts. This results in a long transportation system with numerous work positions and communication links, inevitably leading to increased and dispersed personnel, which is detrimental to safe production and scientific management. In view of this, based on the actual requirements of Daizhuang Coal Mine, and to achieve safe and reliable operation while reducing manpower and increasing efficiency, we developed a mine conveyor belt status monitoring and accident early warning system. This system, together with the dispatch telephone system, early warning broadcast network, and industrial television system, constitutes a complete operation, dispatch, and monitoring network, enabling remote measurement, remote signaling, remote control, and early warning for the entire system. This significantly improves production efficiency and reduces the accident rate, possessing significant theoretical and practical application value.
1 System Principles
The main objective of this system design is to establish a comprehensive detection and early warning system for belt conveyors, including belt speed, overload, slippage, scratches, belt breakage, coupling disconnection, misalignment, smoke, and temperature, using testing technology and control theory.
Since many belt conveyor malfunctions (such as slippage, belt breakage, scratches, overload, and coupling disconnection) are related to speed changes, belt speed has become an important parameter monitored by the mine belt conveyor condition monitoring and accident early warning system. Figure 1 shows the speed changes when various belt conveyor malfunctions occur.
Figure 1. Curve of belt speed change when belt conveyor fails.
For detecting belt misalignment, temperature, smoke, longitudinal tearing, etc., corresponding sensors can be set to detect their status.
The belt conveyor status monitoring and accident early warning system designed in this system can intelligently diagnose and control the system. It can automatically detect faults such as slippage, belt breakage, scratches, overload, and coupling disconnection of the belt conveyor, and provide audible and visual warnings and alarms. When the belt conveyor malfunctions, it can automatically control the belt conveyor and related equipment to stop operation and material supply. The principle block diagram of its control system is shown in Figure 2.
Figure 2. Block diagram of belt conveyor monitoring system
2 Hardware Components
2.1 System Overall Architecture
The mine belt conveyor status monitoring and accident early warning system adopts a fully distributed control structure. It consists of underground control substations and a monitoring master station, as shown in Figure 3. The monitoring host is located in the surface electromechanical monitoring center. A field network bus structure is used between the monitoring master station and the control substations, an array structure is used between the control substations and sensors, and an industrial Ethernet connection is used between the monitoring master station and the monitoring host. The control substations are responsible for data acquisition and control of field equipment. Through monitoring, the entire system's equipment can be monitored and centrally controlled.
Figure 3. Block diagram of the mine belt conveyor status monitoring and accident early warning system
2.2 System Hardware Configuration
The ground-based electromechanical monitoring center is equipped with an Advantech ARK-3390 embedded industrial computer as the host computer, used to centrally display the operating status of each conveyor belt group. The underground configuration includes a KTC101-Z main controller installed near the control panel of the first conveyor head in each conveyor group, serving as a control substation for conveyor belt control and display. A KDW101 mine-use explosion-proof and intrinsically safe power supply box is installed near the KTC101-Z main controller to provide power. At each conveyor head, torque sensors, speed sensors, temperature sensors, belt misalignment sensors, and smoke sensors are configured to detect various operational parameters of the conveyor belt. Starting from the KTC101-Z controller, a MHYBV-7-1-X30 seven-core shielded flame-retardant tensile cable with a plug is connected. The other end of the cable is connected to a KTK101-1 type interlocked public address telephone. From this telephone, a KTC101-2-A type multi-function telephone is connected every 100 meters down to the end of the conveyor belt.
2.3 Voice Broadcasting System
The voice broadcasting system for the main roadway of the belt conveyor requires functions such as voice communication, call points, interlocking buttons, emergency stop via pull wire, start/stop operation buttons, and intelligent input and output. Therefore, the KTK101-1 series combination interlocking loudspeaker telephone is selected for the system.
The KTK101-1 series combined interlocking loudspeaker used in the belt conveyor main roadway operates at 12V, while the loudspeaker system used in the rail transport main roadway operates at 5V. The two are connected through a power conversion module to ensure that in the event of an emergency in the coal mine, personnel at various work sites can be notified in the simplest and fastest way. The system integrates safety broadcasting, dispatching and command, safety monitoring, and public voice communication.
2.4 Video Surveillance System
Video surveillance systems monitor coal mine production processes or key locations, transmitting images of the monitored areas to the dispatch center. This allows production dispatchers to understand the situation in real time and make informed production scheduling decisions. The system mainly consists of cameras, power supplies, monitors, disk arrays, and video streaming software.
3 System Software Design
The system software design mainly includes two parts: tool software design and configuration software design. The tool software handles functions such as parameter setting, system configuration, diagnostics, calibration, and testing of switches, controllers, and remote I/O modules in the network system. The configuration software handles functions such as monitoring and early warning information management for each substation and the central station, dynamic graphical display, data report printing, historical data storage, and dynamic trend analysis.
This system combines Visual Basic, Matlab, and SQL database technologies, using dialog-based programming to achieve data acquisition, analysis, and remote control functions through button operations. Matlab is used to calculate the belt conveyor speed to determine system fault types. A human-machine interface is created using VB to input specific data into the database. The configuration software used is MCGS, which can display the overall operation of the monitoring process, including historical curves, alarm records, parameter settings, status viewing, operation help information, and equipment operation statistics. The interface is required to be simple, user-friendly, and easy to operate. Figure 4 shows the MSCG real-time data monitoring interface.
Figure 4 Real-time data monitoring interface
4. Conclusion
The theoretical research and application of this system have yielded the following innovative results: An abnormal state monitoring model for belt conveyor systems, characterized by belt speed, conveyor torque, and temperature, has been established, achieving high efficiency in fault diagnosis and early warning for belt conveyor coal transport systems. The voice broadcasting system in the conveyor belt roadway and the main mine roadway voice broadcasting system are integrated and linked, forming a complete network for the entire voice broadcasting system. In the event of an accident in the main mine roadway, alarm information can be promptly sent to the conveyor belt roadway. Together with the dispatch telephone system and the underground industrial television system, the system forms a complete operation, dispatch, and monitoring network, enabling telemetry, remote signaling, remote viewing, and remote control of the entire system. Adopting a fully distributed control structure, the system has high security. Even when a control failure occurs on the surface, the underground portion can still achieve centralized control operation. Wiring costs are reduced; the use of a long-distance communication network makes wiring more convenient and significantly reduces cable usage.
References:
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