Development and application of the latest wet dust

2022-08-10
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Development and application of new wet dust collector *

Mechanized Heading Face of coal roadway is one of the dust sources with the most dust production in coal mine. Actually, the measured dust concentration is as high as 800 ~ 3000 mg/m3, and the dispersion is high, among which the particle size that is the most harmful to human body is less than 7 μ M respirable dust accounts for more than 85%, which seriously threatens the safety production of mines and the health of workers. Spray watering has been widely used in coal mines in China for a long time. The test shows that the dust reduction efficiency of spray watering on respiratory dust is 30% - 50%, while the dust reduction efficiency of dust reduction equipment on respiratory dust is generally 75% - 90%. Therefore, it is necessary to develop efficient and practical dust removal equipment to effectively control the dust in coal mine production. Therefore, based on the extensive investigation and analysis of the problems existing in the domestic and foreign dust removal equipment used in the existing coal mines in China, and in view of the production conditions of the machine excavation face, after a lot of theoretical and experimental research, a high-efficiency and practical dust removal equipment with small volume, light weight, convenient movement and installation, simple structure and stable performance has been developed, and a prototype has been processed, and an industrial test has been carried out in the 2709 machine excavation face of Dongpang coal mine

1 structure and dust removal principle of wet dust collector

the structure of dust collector is shown in Figure 1, which is mainly composed of upper and lower guide vanes, dehydrators, water tanks, axial flow fans, slurry discharge valves and water injection holes. The dust removal process is that the dusty gas enters the water surface from the air inlet into the downward guide vane of the dust collector, and the larger dust particles fall into the water tank due to inertia, while the smaller dust particles are captured and settled by fully colliding with a large number of water droplets when passing through the curved channel between the upper guide vanes at a higher speed with the air flow. Under the action of centrifugal force, the air flow containing dust and water forms a certain thickness of water film on the inner wall of the dust collector and the upper and lower guide vanes, which will trap and reduce the dust particles. After the water droplets and mist in the air flow are removed by the dehydrator, they are discharged into the roadway through the axial flow fan; Its dust removal mechanism is mainly the inertial collision, interception and diffusion between the dust particles in the air flow and the liquid surface and atomized droplets. In a word, this kind of dust remover has three kinds of dust removal functions, such as water bath, water droplets, and water film generated by centrifugal force, so it can obtain high dust reduction efficiency. After measurement, the total dust reduction efficiency of the precipitator is more than 98% according to the cost of its combined thermoplastic polymer matrix, and the dust removal efficiency of respiratory dust is also more than 90%. In addition, the dust trapped by water droplets and falling into the water tank will be deposited at the bottom of the water tank or stirred continuously with the impact of the air flow. When the concentration in the water tank reaches a certain value, it will be discharged regularly through the slurry discharge valve, and the water tank will be flushed, and the water supply pipe will replenish fresh water

Figure 1 structural diagram of dust collector

regularly clean the electromechanical 1, 2 - lower guide vanes; 3 - slurry discharge valve; 4 - axial flow fan; 5 - dehydrator

6 - upper guide disables other serial communication equipment flow blades; 7 - shell; 8 - water surface; 9 - water injection hole; 10 - Application of water tank

2 wet dust collector in the heading face

2.1 reasonable determination of ventilation and dust removal system

a reasonable ventilation and dust removal system should be able to effectively control the dust generated by the heading machine, suck the dusty air into the dust collector for purification, and improve the dust reduction efficiency. Therefore, a long pressure short extraction ventilation and dust removal system (Figure 2) is used. The dust removal system has simple management and maintenance, and can effectively eliminate the accumulation and retention of gas, Realize the local purification of dust. Figure 2 ventilation and dust removal system and measurement layout of machine excavation face

1 - cutting arm of roadheader; 2 - suction hood; 3 - soft air duct; 4 - suction duct

5 - roadheader platform; 6 - driver's place; 7 - reprint place; 8 - dust collector; 9 - fan

10 - bridge belt conveyor; 11 - press in air duct

since the sectional area of the excavation roadway is 12.25 m2, the distance between the air outlet of the press in air duct and the international influence of China's plastic machinery industry continues to increase during the excavation process, and the working face should be less than 15 m; The distance between the air inlet of the dust collector and the working face shall be less than 5 m, and the driver shall be advanced

2.2 installation and use method of wet dust collector

due to the particularity of underground working conditions, it is required that the dust removal equipment should be moved, installed and disassembled conveniently, and ensure that the dust removal equipment and the roadheader move forward synchronously, reducing the labor intensity of workers. After repeated consideration, the 2709 working face of Dongpang Coal Mine adopts the installation method of dust removal system as shown in Figure 2. That is, the dust collector and fan are installed on both sides of the bridge belt conveyor, the air suction duct is suspended on both sides of the roadheader, and the dust suction cover is installed on the cutting arm of the roadheader. The rigid and telescopic air ducts are respectively used between them to connect the dust collector and fan, so that two independent dust removal systems are formed on both sides of the roadheader and the bridge belt conveyor, which do not interfere with each other and do not affect the operation of the tunneling workers. Since the processing air volume of one dust collector is 60 ~ 70 m3/min, two dust collectors are used in parallel. The resistance of each dust removal system is about 1300 PA, so two jbt-42 explosion-proof axial fans with motor power of 4 kW are selected

before the operation of the dust remover (or the start of each shift), first put the dusty sewage in the dust remover into the tunnel ditch with a hose, and then inject clean water into the water tank. The water level indicator indicates a certain amount of water injection. After the dust remover operates for a certain time (about 1 day), discharge the sewage and inject clean water once again. The operation is relatively simple. The power supply lines of dust removal equipment, roadheader and press in local fans shall be equipped with wind power locking devices. Once the local fan stops operating for some reason or the gas in the working face exceeds the limit, the dust removal equipment and the roadheader can be powered off and stopped in time. Only when the press in local fan operates normally and the gas concentration in the working face does not exceed the limit, the dust removal equipment and the switch of the roadheader can be started

2.3 test results and analysis

after the dust removal system is installed according to the requirements of the above test scheme, the dust concentration is measured, and each group of data is the average value of the measured values after multiple shifts. During the measurement, the air volume at the air outlet of the pressure type air duct is about 105 m3/min, the air intake of the left and right suction ducts of the dust removal system are 48 m3/min and 53 m3/min respectively, and the exhaust air volume of the left and right axial flow fans are 59 m3/min and 62 m3/min respectively, so the total air intake of the whole dust removal system is 101 m3/min, and the exhaust air volume is 121 m3/min, which is about 20 m3/min

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