Monitoring and control device for the flow of the

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The monitoring and control device of water injection hole flow

Wang Tai 1 and Peng served as 2

(1. Beijing Institute of industry and technology, Beijing 100042; 2. China University of mining and technology, Xuzhou, Jiangsu 221008)

1 introduction

in underground coal mines, water injection into coal seams is a fundamental measure to prevent and control dust. At the same time, it is also an important measure to prevent rock burst and soften coal bodies to improve the recovery rate of top coal in the process of top coal caving mining. The flow rate of coal seam water injection is a key index affecting the quality of coal seam water injection. Therefore, it is of great practical significance to study the monitoring and control of water injection flow in coal seams

2 function of monitoring device of water injection system

for a long time, the flow of coal seam water injection is obtained through the flow meter. In this special working environment in the coal mine, the flow meter used is not easy to read and cannot remember the cumulative flow. More importantly, it cannot realize effective and automatic control of water injection flow. The monitoring device of coal seam water injection system realizes the automatic monitoring and monitoring of the flow of multiple water injection holes. It has the following functions: monitoring the flow of coal seam water injection holes; Display the cumulative flow; Monitor whether there is leakage in the pulsating pipeline of the water injection hole due to leakage or temperature change after 24 hours of startup; Realize real-time display; The display can be reset

3 composition of monitoring device of water injection system

3.1 composition of hardware system

the hardware system of monitoring device of coal seam water injection system is composed of explosion-proof box, power supply, main control board, display, SSR group, 3-way flowmeter and 3-way solenoid valve. The structure of the hardware system is shown in Figure 3-1

(1) explosion proof box: the dotted box in Figure 3-1 indicates the explosion-proof box. The box adopts ayj-1 mining explosion-proof shell, which has good explosion-proof performance. The power supply, SSR group, main control board, display module and other devices are all installed in the explosion-proof box to achieve the purpose of electrical explosion-proof. The box has 5 wiring ports (including 1 Bell), 1 display window and 1 concealed external switch, which can basically meet the design requirements of the device

(2) power supply: the linear integrated power supply is adopted, and its overall size is 160 mm × 130 mm × 45 mm, the input voltage is 127vac, 50 Hz, the output voltage is 5 VDC, 12 VDC, the power is 22W, and the output current fully meets the requirements. This solid-state relay requires a small input control current, which can be directly driven by integrated circuits such as TTL, HTL, CMOS or by adding simple auxiliary circuits. It is suitable to be used as the control element of output channel in microcomputer measurement and control system

(4) main control board: it is an application system based on Philips 80C552 single chip microcomputer, which can control the opening of solenoid valve, transmission and display data, data storage, pulse number measurement of flowmeter and expansion I/O. it also has the characteristics of one board with multiple functions, and is easy to interface with other application systems; All chips are CMOS chips, so it has the advantage of low power consumption; It is also equipped with Watchdog monitoring circuit, so that the system can operate reliably

the structure of the main control board is shown in Figure 3-2. (5) Display screen: nyc1602-03sgn liquid crystal display (LCD) is adopted, and the liquid crystal display is 5 × 7 dot matrix display module, 16 characters per line, 2 lines of display. The display module has led Le, which adopts electro-hydraulic loading, sensor force measurement, digital display force value, printer print force value data, and automatically converts the compressive strength D backlight power supply, so that the LCD is easy to read under the dark conditions underground

(6) solenoid valve: mining explosion-proof solenoid valve is adopted, with input voltage of 127 VAC and power of 20 W. its flow and pressure can meet the requirements of coal seam water injection system

(7) flowmeter: the turbine flow sensor (lwgy-15-b) is selected. Its nominal diameter is 15 mm, the maximum working pressure is 6.3 MPa, the flow range is 0.6 ~ 6 m3/h, the accuracy is 0.5 grade, the power supply of the preamplifier is + 12 V, and the distance from the sensor to the display instrument can reach 500m. Its technical parameters fully meet the requirements of coal seam water injection

working principle: when the measured liquid passes through the sensor, its internal impeller rotates with the help of the kinetic energy of the liquid. At this time, the impeller blade makes the magnetic resistance of the magnetic circuit in the detection device change periodically, so an electric pulse signal proportional to the flow is induced at both ends of the detection coil, which is amplified by the preamplifier and transmitted to the main control board. Within the measurement range, the flow pulse signal of the sensor is directly proportional to the volume flow, and this ratio is the instrument coefficient k:

where f is the signal frequency (Hz); Q is the flow (m3/h or L/h); N is the number of pulses; V is the total volume (M3 or L)

in the newly-built factory building of the enterprise, the quantity sensor should be far away from the external electromagnetic field. If it cannot be avoided, necessary shielding measures should be taken. In addition, the flowmeter must be installed vertically for the measured value to be accurate

3.2 composition of software system

the software system uses PL/M-51 programming language and MCU assembly language for mixed programming. PL/M-51 language is a high-level programming language specially designed by Intel company for developing MCS-51 single chip microcomputer system software and application software like other instruments

using PL/M-51 language to develop software can improve efficiency, shorten the development cycle, and facilitate software maintenance and modification. However, the compiled object code is usually longer than that written directly in assembly language, and it is limited by the size of the simulation program that the MCU development system can use. Therefore, the mixed programming of PL/M-51 language and assembly language is beneficial to the development and maintenance of software system, and shortens the length of program object code

the software system adopts modular design, and has 10 module functions, including main program, multi byte binary number conversion to floating point number subroutine, storage subroutine, delay and zeroing subroutine, multi byte floating point number multiplication subroutine, display initialization subroutine, 16 bit binary number conversion to BCD code subroutine, calling o-f display subroutine, pulse number conversion to flow subroutine, interrupt and flow display code subroutine

software flow of the monitoring device system

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