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(1) Determine the wind speed with a wind meter. Commonly used wind meters are cup type and wing type.
(2) The wind speed is measured by a pyroelectric anemometer and a pitot tube differential pressure gauge. The thermoelectric anemometer is divided into a hot wire type and a hot ball type. Thermoelectric anemometers are more convenient to operate, but existing thermoelectric anemometers are prone to damage, and dust and humidity have a certain impact on them, which needs further improvement for widespread use in mines.
(3) When the wind speed is low or the air leakage of the ventilation structure is identified, the air moving speed can be approximated by the smoke method or the smell method.
(4) Measurement by wind speed sensor. Commonly used wind speed sensors are: ultrasonic vortex street wind speed sensor, ultrasonic time difference method wind speed sensor, and thermal effect type wind speed sensor.
Second, the determination of mine ventilation resistance
There are generally three methods for measuring the resistance of mine ventilation: the measurement method of precision differential pressure gauge and pitot tube, the measurement method of constant temperature differential pressure gauge, and the measurement method of empty box barometer.
Third, gas detection
Gas detection actually refers to methane detection, which mainly detects the volume concentration of methane in the air. Mine gas detection methods include laboratory sampling analysis method and direct underground measurement method. With the portable gas detection alarm, the gas concentration in the workplace can be detected at any time, and the gas concentration can be continuously monitored in real time using a gas sensor. Coal Mine Gas detection equipment used, classification by the detection principle: optical, catalytic combustion, thermal conductivity, semiconductor gas type, etc., can use the site, measuring range and accuracy requirements, select a different detection principle Gas detection instrument.
Fourth, carbon monoxide detection
Carbon monoxide is a highly toxic gas. When inhaled into the human body, it causes hypoxia in human tissues and cells, causing poisoning and suffocation. A large amount of carbon monoxide will be produced in coal mine fires, gas and coal dust explosions and blasting operations. For the health of the miners, the Coal Mine Safety Regulations stipulate that the concentration of carbon monoxide in the underground working place should be controlled below 24×10 -6 . Carbon monoxide detection instruments commonly used in coal mines include electrochemical, infrared absorption, and catalytic oxidation.
V. Oxygen detection
For nature's life, oxygen is indispensable, and the reduced oxygen content in the air can make people feel uncomfortable or even suffocate. Therefore, the "Safety Regulations for Coal Mines" has strict regulations on the oxygen content of mines. The commonly used methods for detecting oxygen in coal mines are gas chromatography, electrochemical and paramagnetic methods. Among them, the gas chromatograph is generally installed on the ground, and the concentration of the gas component of the mine is analyzed by manual sampling.
Sixth, temperature detection
Temperature sensors commonly used in coal mines include thermocouples, thermal resistors, thermistors, semiconductor PN junctions, semiconductor infrared thermal radiation detectors, thermal noise, and optical fibers. The principle of thermocouple and thermal resistance has been widely used in industry (ground); the application of semiconductor PN junction principle in the range of -100 to +100 °C is also very successful, and there are many applications in coal mines.
Seven, smoke detection
Fire is one of the major disasters in coal mines. Therefore, it is of great significance to establish, improve and equip fire prevention devices, strengthen fire monitoring and prevent fire accidents. Smoke detection is an important part of fire detection.
Eight, switch detection
In the coal mine monitoring system, the status and proportion of the switch quantity detection increase with the improvement of the level of production automation, playing a very important role in working conditions and production monitoring. The switch sensors used in the coal mine monitoring system mainly include equipment opening and closing, damper opening and closing, feed switch status, air duct switch, temperature and humidity control, smokeless smoke, current and voltage control. To ensure the normal operation of the monitoring system, the detection of the switching quantity must be strengthened.
Nine, detection instruments and sensors
The main contents of coal mine safety detection and monitoring instruments include: detection of gas concentrations such as methane, carbon monoxide and oxygen in underground mines; detection of environmental parameters such as wind speed, air volume, air pressure, temperature and dust concentration; monitoring and monitoring of the operating status of production equipment, etc. . The instrumentation can be mechanical, chemical, optical, electronic, and the like. Such as U-shaped differential pressure gauge, mechanical wind gauge, chemical test paper, light dry gas detector, etc. However, sensors are generally electronic, and can be recorded and transmitted after converting physical quantities into electrical signals.
(1) Main portable measuring instrument types
The safety detection instruments currently used by domestic coal mining enterprises mainly include: 1. Optical interference gas detector, which is mainly used for detecting methane and carbon dioxide, and the detection range is 0% to 10%, 0% to 40%, and 0% to 100%. 2. The thermal catalytic gas detection alarm device mainly detects low concentration methane, and the detection range is 0% to 5%. 3. Intelligent gas detection recorder, mainly detecting methane concentration, taking single chip as the core, carrier catalytic component and thermal conduction component as sensitive components, using carrier catalytic component to detect low concentration methane and thermal conductivity component to detect high concentration methane, realize 0 From % to 99% of full scale measurement, the instrument can automatically correct the error. 4, gas, oxygen two-parameter detector, equipped with two sensitive components to detect methane and oxygen, while continuously detecting methane and oxygen concentrations. The latest development of four-parameter detector, simultaneous determination of methane, oxygen, carbon monoxide and temperature, carbon monoxide measurement range: (0 ~ 999) × 10 -6 , methane measurement range: 0% ~ 4%, oxygen detection range: 0% ~ 25 %, temperature detection range: 0 ~ 40 °C. 5, gas alarm miner's lamp, attached to the miner's lamp a gas alarm circuit, that is, gas alarm miner's lamp. The instrument is powered by a miner's lamp battery and has two functions of illumination and gas over-limit alarm. There are dozens of different structural forms of products. From the point of view of the alarm circuit, the early products put the circuit in the battery, and the recent products put the circuit on the headlight or the mine cap. Some are installed in front of the mine cap, some are installed in the back of the mine cap, and are installed on both sides of the mine cap. Carbon monoxide detection alarm device can continuously or point to measure the concentration of carbon monoxide in the working environment. The instrument can be detected when it is turned on. The detection range is (0~2000)×10 -6 .
(2) Main mining sensor types
At present, domestic mine sensors mainly use 12~24VDC power supply, which is generally intrinsically safe. It usually has the function of continuously converting the physical quantity to be tested into standard electrical signal to the associated equipment, and providing local display and over-limit alarm. Some also have remote control adjustment, power failure control, fault self-calibration and other functions (such as the series of sensors produced by the Chongqing Branch of the Coal Branch). The sensor analog output signal usually adopts 200~1000Hz, 1~5mA standard signal, switch output 1mA/5mA (two-wire system); ±5mA, 0V/5V (four-wire system) and other standard signals. The sensor signal transmission distance is generally not less than 1km.
The sensors are mainly of the following types:
1. Intelligent low-concentration methane sensor, the stability index is 1 to 3 weeks, and the component life is 1 to 1.5 years. Measurement range: 0% to 4.00% (or 0% to 10.0%).
2. Intelligent high and low concentration methane sensor, compared with low concentration methane sensor, increased thermal conductivity type high concentration methane sensor. The low-concentration still uses the thermal catalytic element. When the concentration exceeds 4%, it automatically switches to the output of the thermal conductive element, and cuts off the working power of the thermal catalytic element, thereby protecting the thermal catalytic element from the high concentration of methane impact poisoning. The sensor measurement range is: 0% to 40.0%.
3, carbon monoxide sensor, the detection range is (0 ~ 999) × 10 -6 , the life of sensitive components is not less than 2 years.
4. The wind speed sensor is mainly installed in the wind measurement station, the inlet and return wind lanes and the working face of the mining area, etc., to monitor the wind speed and direction of the roadway. The measurement range is generally 0.3 to 15 m/s.
5. The opening and closing sensor of electrical equipment is mainly used to continuously monitor the opening and closing conditions of various electromechanical equipments with coal supply current greater than 5A.
6. Feeding sensor, mainly monitor whether the power cable power supply is cut off, and use it with the breaker. It can timely feedback whether the breaker is effectively implementing the power-off function.
First, the wind speed measurement