Introduction to installation method of explosion-proof monitoring equipment in coal mine area

By 2015, the output of small coal mines below 300,000 tons will be reduced to 500 million tons, accounting for 13% of the country's total coal production. The total coal output will reach 3.6-3.8 billion tons, and the large coal mines will account for 2.5 billion tons, which will increase from 56% to 66% during the 11th Five-Year Plan period. Large coal mines will become the leading producer of coal. This shows that China's coal industry will usher in a booming era. However, the continued development of any industry is pros and cons, and the coal industry is also the same. There are also many flaws hidden behind the industrial prosperity. In addition to environmental pollution, frequent coal mine safety incidents have also received much attention.

Coal mine explosion-proof monitoring equipment selection

Due to the characteristics of low voltage, small current, low power and high frequency, the application of video surveillance in coal mine safety monitoring must consider the light changes under the explosion-proof requirements, the stability and reliability of video transmission effects. Through the low-light night vision camera equipment in the high-risk environment, it is necessary to monitor not only the underground operation state of the coal mine, but also provide high-quality video images. Therefore, under the requirements of explosion protection, the design and selection of coal mine monitoring equipment is more important. The use of explosion-proof devices is mainly to make the electrical equipment such as cameras, lenses, and pan-tilt not cause burning or even explosion in the dangerous environment of coal mines or underground. Usually these equipments must have a considerable thickness of cast aluminum or stainless steel to make a strong anti-internal explosion-proof casing, so you must pay attention to the following conditions in the construction installation to use in coal mine video surveillance, these equipments include:

Internal pressure explosion-proof protective cover

Adopting the principle of internal pressure explosion-proof, using a protective cover made of cast aluminum or stainless steel of a certain thickness, the window glass is made of steel elastic material glass, and has anti-explosion function. The internal pressure explosion-proof is usually sealed, so the camera to be used must be able to withstand higher Operating temperature, while protecting the enclosure must be resistant to corrosion. As for the installation of other accessories, except for the internal heating and defogging equipment, the rest can be omitted, so as not to be counterproductive.

Internal pressure explosion-proof gimbal

As for the part of the rotary pan/tilt head, since the starting motor circuit function itself, the starting current may generate sparks. Therefore, the explosion-proof pan/tilt head on the outer casing must be made of high sealing material and made of aluminum or stainless steel, and must be resistant to acid and alkali corrosion and thickness. Has the ability to withstand internal pressure explosions. Although the rotary gimbal is large in size, the weight and volume are a major challenge for engineers in the high installation requirements.

Monitoring and installation of explosion-proof junction box

The monitoring explosion-proof control box used in the mining area is different from the general equipment wiring equipment. From the connection of the cable to the distribution to the front-end fiber or network transmission equipment, from the control receiver, the main power switch to the leakage circuit breaker and the arrester or surge absorption equipment are all associated with the explosion-proof control box. In addition, these devices are prone to gas and gas explosion, so the material and thickness of the explosion-proof junction box is particularly important. In general, the size and size requirements, all equipment must be put into the analog wiring, and the joint transition is smooth, it can be used, otherwise the terminal equipment box with too small space will be used because of the cost, but the equipment temperature will be too high. Fall off.

Design and construction of coal mine explosion-proof monitoring equipment

For the explosion-proof monitoring design of coal mines, in addition to the design specifications of the explosion-proof monitoring and control system, reference may also be made to the explosive environmental electrical and application design standards formulated in the explosion-proof part of China, including GB50198-94, GA/T70-94, GB/T15411- 1994, GB/T13953-1992 is particularly worthy of attention. When designing coal mine explosion-proof safety monitoring, the design and installation construction should be determined according to the type, level and material characteristics of the dangerous source released from the well and the well, environmental conditions, etc. Therefore, it is also necessary for the coal mine safety monitoring in construction and Have some understanding and understanding on the installation.

Explosion-proof construction and installation precautions for coal mine monitoring equipment

As shown in Figure 1, the coal mine mainly includes the following points in monitoring the installation and precautions for explosion-proof construction:

· The camera must be protected in the explosion-proof protective cover. The protective cover should also have a certain explosion-proof level according to the needs of the environment;

· In the explosion-proof demand, infrared LED lighting camera is not suitable as a low-light night vision monitoring of underground;

· In the coal mine explosion-proof area, all pipelines except the pipeline used for the grounding line and the pipeline buried in the underground, all other pipelines must be configured with metal galvanized steel pipes;

· If it is a rotary camera, it must be an explosion-proof pan/tilt or an integrated explosion-proof structure;

· Whether it is outside the well or in the well, the camera must be equipped with a grounding wire to prevent the current generated by the leakage from causing explosion or gas explosion;

· Explosion-proof pipelines must be provided with a drain device to prevent condensation from causing corrosion of the pipe wall caused by water in the pipe;

·The metal explosion-proof pipe and the metal galvanized pipe connection do not need to use the explosion-proof isolation joint (DRAIN), and fill the explosion-proof isolation glue (or explosion-proof pipe sand filler), the explosion-proof pipe sand filler is filled in the pipe at least The length of 45 cm (18 inches) is filled with explosion-proof insulation to prevent spark explosion caused by short circuit in the pipe;

· Equipment and metal galvanized pipe or hose connection should be separated by explosion-proof isolation joint;

· The connection between the explosion-proof zone and the non-explosion-proof zone must also be isolated by explosion-proof isolation joints (Fig. 2);

· All pipelines entering the equipment should be put into construction from the bottom of the equipment or explosion-proof box as much as possible to avoid loosening or water in the pipeline;

· The power line and video signal and lightning protection grounding line must be configured separately to avoid tempering to damage or explode the equipment;

·The joints in the explosion-proof terminal equipment connection box must be lockable or screw-terminally fixed to prevent the line from falling off, especially the power supply part, causing spark explosion;

· Most of the image door of the explosion-proof box of the camera terminal is fixed by screws. After the equipment is adjusted, it must be reversed in the clock direction. The fixing screws are tightened one by one to balance the pressure of the cover to avoid airtightness and leakage. Gas explosion

• The system ground must be grounded at one point. The grounding shall be copper wire, and shall not form a closed loop, and shall not be mixed with the high-current power ground;

· When the explosion-proof monitoring system is equipped with an independent grounding device, its grounding resistance shall not exceed 4Ω (refer to the national regulations);

· If fiber optic cable transmission is used in the coal mine well, the optical transceiver casing on each well tunnel should be grounded, and the equipment that matches the monitoring points, such as the camera, should be grounded in parallel. If the cable racks in the pits are connected, each trunking should be grounded to ensure safety;

· The equipment in the coal mine area that is vulnerable to lightning strikes is a front-end camera. If it is installed outside the well, the equipment must be equipped with a lightning rod.

The above are the precautions and measures for coal mine safety monitoring in construction and installation. Because general coal mines are filled with dangerous factors such as methane and coal dust explosions, some mines try to transmit wirelessly, and mobile monitoring systems are beginning to enter coal mine safety surveillance. The video signal and the camera power supply are transmitted in a common cable. The camera itself has an ultra-high-brightness LED white light, which is suitable for use in poor lighting conditions under the mine or in no light environment. It can capture clear images under low illumination conditions, making coal mine safety monitoring. It can be safely applied to the working area of ​​the deep excavation face of coal mines, providing a broader security guarantee for mine safety monitoring. As for the digitalization of coal mine safety monitoring, there are also some coal mines that are connected to each other through a switch to form a local area network, and through a coal mine area network that consists of a twisted pair cable and an Ethernet switch, or a fiber-optic Ethernet exchange area network. The coal mine safety monitoring has also gradually entered the field of all-IP networking in the construction and installation stage.

Conclusion

The goal of achieving safe production in coal mines is inseparable from the construction of mine safety precautions. However, in the special monitoring environment of mines, the implementation of security equipment must meet the requirements of explosion protection. The explosion-proof requirements of coal mines should be the common basic conditions for all six safety systems in coal mines. However, it is difficult to completely control the environmental changes in coal mines. Therefore, it is only necessary to continuously improve the construction and installation methods and conditions of video surveillance systems. More powerful monitoring performance under restrictions.