| Dust is one of the five disasters in coal mine. With the development of modern mining technology, the mining mechanization level becomes higher and higher, so the high yield and efficiency of the working face was achieved and the great economic benefits for the coal mine was obtained, but the serious dust disaster problem also was brought. On the one hand, Coal mine dust is seriously harmful to human health, especially the respirable dust. Coal miners are vulnerably suffered from occupational pneumoconiosis, when they are perpetually exposed in the operating places with high dust concentration. According to the statistical results, the pneumoconiosis patients in coal industry are beyond 300000, which is accounting for about half of total number of china, the pneumoconiosis not only costs the government a lot of medical expenses each year, but also brings serious disasters to patients and their families. On the other hand, the coal mine dust with high concentration is always easy to trigger dust explosion. Once the underground coal dust explosion occurred, the heavy casualties and enormous economic loss would be brought, even the serious mine destruction would be caused by the explosion accidents. In addition, the work-place dusts can cause the deterioration of working environment, reduce visibility, debase labor productivity, increase the rate of occupational accidents, cause diseases of skin and eye and accelerate the abrasion of machinery and equipment.The coal-mining face is the place where the largest amount of coal mine dust production and the highest dust concentration, especially, in a fully-mechanized coal mining face (abbreviation:fully-mechanized coal face). When the shearer cuts coal, the dust concentration in the work-face is 8000-10000mg/m3. Though many dust control measures, such as the coal seam water injection, dust suppression by spraying are adopted in current working face, the dust concentration, especially the concentration of respirable dust in the work-space of shearer drivers, is difficult to reach the industry standards. So the research on using the partition characteristics of air curtain to prevent the coal dust generated by cutting drum shearer from diffusion to the work-space of shearer drivers, reducing the dust concentration by a new method is carried out in this dissertation from theoretical analysis, experimental study, numerical simulation and field test. The main research contents are as follows:(1) Basing on fluid mechanics, aerosol mechanics and aerodynamics, the diffusion motion law and affected factors of dust in mechanized mining face is studied.(2) By measuring basic distribution law of dust and airflow in mechanized mining face, the dust distribution law and airflow motion characteristic in fully-mechanized coal face shearer are analyzed.(3) According to the plane jet theory and the shielding action of air curtain, the dust separation theory and method of air curtain in fully-mechanized coal face is put forward and the dust separation theory model of air curtain is established.(4) Through the comprehensive analysis on flow field of fully-mechanized coal face and measurement data of dust distribution, the prevention effect of air curtain and diffusion of respirable dust during shearer cutting coal are simulated by software FLUENT, and the design parameters and the installation location, installation angle of air curtain are also analyzed. Finally, the best air curtain parameters of design and installation are obtained.(5) The similar simulation experiment of the changeable conditions at experimental lab is carried out, the results obtained in lab are concordant with the results obtained from theoretical analysis and field test. Finally, the prevention effect and design parameters and installation parameters are validated.(6) Industrial test was carried out in 1326 and 1528 work-face of GeQuan coal mine, HeBei JinNiu Energy Co., Ltd(formerly Xingtai Mining Bureau).The results show that the air curtain installed in fully-mechanized coal face shearer acts as a "transparent invisible barrier", which can effectively prevent the dust from diffusion to work-space of shearer drivers during coal shearer cutting coal, especially the diffusion of respiratory dust, and greatly reduce dust concentration of the work-space of driver in the fully-mechanized coal face. The device is simple and practical to use in low cost, does not disturb the driver's attention and operation, which obtains highly praise. So a good economic safety benefits and social effects of practical application are obtained, it has a broad prospects for the promotion and application.The principal innovations in this dissertation are as follows:(1) The ideas that using an air curtain to prevent dust diffusion to the driver in the fully-mechanized coal face during coal shearer cutting coal, debasing the dust concentration in the work-space of shearer drivers, improving the operating environment of the shearer drivers and increasing the safety production reliability, are first proposed.(2) Aim to the characteristics of work-space in fully-mechanized coal face, the dust separation mechanism of air curtain in work-face is studied, and the theoretical model of dust separation theory is established. Base on the rotating air separation theory, the dust control theory of rotating air curtain is put forward; relations between the efficiency of the dust separation and dust particle size are analyzed. The effectiveness of dust diffusion suppressed by air curtain is demonstrated.(3) By theoretical analysis and field testing study, the conclusions that the dust diffusion from coal wall to the driver is the comprehensive effect results of perturbation airflow, dispersion and diffusion of dust, are obtained.(4) By theoretical analysis, numerical simulation and field testing study, the best air curtain design and installation parameters on testing condition are obtained, and the technology problem of respirable dust beyond standard in work-place of driver is effectively solve. |
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