Application of automatic monitoring system for mine downhole gas pressure

0 preface

The mine underground ventilation system generally transports fresh compressed air to the underground gas storage tank through the air compressor station on the surface, and then transports it to each working point separately, and simultaneously uses the fan to extract the dirty air from the underground. In general, it pays great attention to the energy saving of air compressors and the air extraction of wind turbines. The use of frequency converters and automatic control technology has achieved good results, but the management and control of downhole gas pressure applications are not enough, and the complete set of compressed air is rarely used. The control system manages and controls the compression, which wastes a lot of compressed energy. If the gas volume is controlled manually by the pipe gate valve, since the downhole gas pipe extends very far and is widely distributed, more labor costs are required, and the gas pressure and flow rate of the gas pressure cannot be displayed, and the gas pressure can not be accurately and timely controlled. This requires a remote automatic monitoring system for pressure gas, according to
The downhole operating point conditions, ventilation requirements, and equipment opening conditions are used to adjust the amount of compressed air.
1 design of automatic gas pressure monitoring system
With the development of various detection sensors, the development of single-chip microcomputers, network communication and computer technology, remote automatic monitoring systems have been widely used in industrial projects. The system is designed based on the above related technologies. The system consists mainly of: the main computer located in the monitoring center, the optical transceiver, the optical module switch, the optical fiber terminal box, and the remote control box of each middle layer, installed on the compressed air pipeline. Monitoring, control instrumentation, communication fiber, in which the remote control box is installed:
The data acquisition board, serial server, optical transceiver and corresponding circuit components are used to receive, process and transmit various signals and instructions. The whole monitoring system consists of the upper monitoring management layer, the intermediate communication layer, and the lower terminal signal acquisition layer. The system structure is shown in Figure 1.

1.1 host computer monitoring system
The monitoring system software is the PC software based on PC data processing terminal written by Visual C++6.0 platform, which mainly includes 5 functional modules: parameter setting module, data acquisition module, data processing module, control output module and data management. Module, through each set of data exchange interface and multi-line transmission
Real-time data exchange and storage. The main functional requirements and objectives of the monitoring system are: network communication and data exchange with the remote terminal controller; data calculation, conversion, processing; data storage backup and printout; real-time display of system pipeline parameters; real-time data curve and history Data curve graphic display; remote control regulating valve; equipment fault alarm and recording.
1.2 Communication System
The role of the intermediate communication layer is to connect the upper-level monitoring management layer and the lower-end terminal signal acquisition layer. The serial communication is used between them. The communication mode is the main-slave communication. The upper monitoring machine sends the query command to the lower computer. The lower computer confirms the query. After the instruction, the collected signal is transmitted back. The signals collected by the lower computer terminal are transmitted through the RS-232 interface, the serial port server, the optical transceiver, and the optical module switch, and the serial server is a communication interface protocol converter for completing data conversion between the RS-232 terminal and the TCP/IP. The signal interface thus output is the normal network port RJ45. Due to the long transmission line and large signal interference, the transmission of electrical signals can not meet the requirements, while the optical fiber communication transmission has large information, long transmission distance, good anti-interference, high security, and small fiber, light weight and convenient laying. Simple, so the use of optical signal transmission, which requires the conversion of electrical signals into optical signals, the choice of fiber optic transceivers, the use of optical fiber communication to transmit signals, because the computer receives electrical signals, so the optical signal needs to be converted before the upper monitoring machine For electrical signals.
1.3 lower terminal signal acquisition system
The lower terminal signal acquisition system is based on STC12C5412AD microcontroller, designed by Keiluvision2 software, mainly including A/D421 chip for data conversion, 8-channel 10-bit precision ADC terminal, EEPROM function X25045 chip, RS-232 interface conversion chip MAX232. 3 channel 0-5V analog input circuit, 1 channel switch input circuit, 1 channel 4-20mA analog output circuit, 1 channel switch output circuit, other related functional circuits, and signal acquisition terminal installed on the compressed air pipeline Monitoring and control equipment. The hardware structure of the lower field monitoring system is shown in Figure 2.

The monitoring and control equipment installed on the compressed gas pipeline are: flow meter, pressure sensor, intelligent regulating valve, switch butterfly valve. The flowmeter is transmitted to the single-chip microcomputer with a flow value of 4~20mA, and the pressure sensor is transmitted to the single-chip microcomputer with a pressure value of 0~5V. The intelligent regulating valve adjusts the opening degree of the valve according to the instruction of the upper computer, and feeds back the valve opening value to the valve opening value. The system, the switch butterfly valve opens or closes the valve according to the instruction of the upper computer, does not adjust the valve size, and feeds the valve switch state to the system. The signal acquisition terminal collects the analog signal. It needs to use the A/D conversion function of the STC12C5412AD microcontroller to convert the analog quantity into a digital quantity. Similarly, the instruction of the upper computer needs to be converted and transmitted to the signal acquisition terminal.

The signal acquisition system has multiple signal collection terminals. When the PC communicates with the collection terminal, the node must be identified according to the unique identification address. Therefore, the IP address of the host and the IP address of the serial port server of each signal collection terminal are set by the upper computer. They are in the same LAN, and the signal acquisition terminal dial switch is used to set the identification address of each signal acquisition terminal.
2 function of the automatic gas pressure monitoring system
(1) Collect the flow, pressure, gate valve opening and other parameters of the pressure of each layered pipeline, and display it in real-time data and graphs on the monitoring system screen, so that the pressure flow value and pressure value of each place can be known in the monitoring room. , pipe switch status and gate valve opening value.
(2) Remotely control the control valve of each point, according to the production task, construction operation requirements, gas equipment start and stop, etc., adjust the ventilation point of each ventilation point in real time.
(3) Safety monitoring, monitoring the field equipment and communication status at each point. When the equipment fails or the communication is disconnected, the monitoring system will display the corresponding fault alarm. The maintenance personnel can display the timely maintenance according to the fault of the monitoring system.
(4) Automatic/manual control, the switch and opening degree of each control valve can be manually modified at any time. It is also possible to automatically adjust different functions at different times by setting each control valve status parameter.
(5) Automatic over-limit alarm, according to different gas supply requirements, set the upper and lower limits of the pressure flow and pressure value at each point, and issue an alarm when the measured data value exceeds the range, so as to adjust in time.
(6) Recording, querying and printing of events and data, the computer automatically stores the data and events of the system according to the monitoring system design, and the monitoring system can query the historical data of each parameter and the operation of the device, and can automatically generate according to the query of the database. Various reports.
3 conclusions
With the development of society, safety and energy are getting more and more attention. The state has stricter requirements for the safe production, energy consumption and standard management of mining enterprises. Digital mines are a development direction of modern mines. Mines, first of all, the process systems and equipment of the mine must be automated and networked. This mine underground gas pressure automatic monitoring system adopts advanced network technology and automatic control technology, and is equipped with hardware equipment with reliable quality, stable performance and simple mechanism to realize automatic management of compressed air. System after silver Mao Nanjing Lead Zinc Mining Limited underground install applications and achieved good results: the staff in the control room will be able to dispatch real-time understanding each point pressure and gas equipment, the control valve is controlled according to each point needs remote, real-time Adjusting the pressure of each ventilation point; if the equipment is faulty, it can be immediately found, and the personnel maintenance can be arranged in time; the management level and safety performance of the mine pressure control are improved; the gas waste is reduced, the power loss is reduced, and the air compressor power ratio of the air compressor station is improved throughout the year. In the past years, it can save 240,000 kW·h; the staff of the gas pipeline is reduced. In the past, one person was required to inspect and adjust the pipeline. Now, as long as the management personnel or the dispatcher manages the monitoring system part-time, four workers can be reduced, saving Labor cost; stable system operation, safe and reliable hardware, low failure rate and low maintenance cost.
references:
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