Mechanism Research Of The Blocking In Raw Coal Bunker

Coal bunkers are very popular used in power plant. However, material blocking phenomenon often occurs in the process of materials get out of the coal bunker, which seriously affect the normal operation of the equipment in power plant, especially in the rainy weather, the blocking coal phenomena occurs more harsh, even shut-off phenomenon occurs. Large thermal power plants which are installed pulverizing systems, once the blocking phenomenon occurs, the units would be forced to down load, the boiler combustion would be instability, large amounts of oil would be required, if gets more serious, boiler extinguishing and unplanned outage of unit could also be caused. Therefore, the coal blocking problem is required solved urgently.Through two tests, we find the main factors that caused coal blocking. The first test is the rotary hopper test. Through this experiment, we found the different influences of the outer moisture, ash content and particle size on the fluidity of raw coal, the results show that the surface moisture content of raw coal plays a dominant role in its fluidity, and the fluidity shows a depravation with the increase of the surface moisture content. Coal blockage occurs easily when the surface moisture content was above8%. The second test is the silo test. Through this test, we found the effects of bunker sidewall angles,coal, and moisture content on the coal blocking, and the results also show that the moisture content is the main reason of blocking. Through the above two tests, we can draw a conclusion that the higher moisture content of raw coal is the main reason that caused blocking.After we find the main reason of raw coal blocking is moisture content, the next test is the removal of moisture of raw coal until its moisture content lower than8%. This part also contains two tests. The first test is how gas flow in the coal particles. Through this test, we found the relation between the gas flow, the time of the gas got through the coal bed and the static pressure difference of coal bed under the nature and high bulk density. The fan flow of raw coal dewatering test could be calculated through the above two relations, which lays the theoretical foundation for the raw coal dewatering test. The second test is the use of wire resistance to hit air, and use hot air to remove moisture of raw coal, Through this test, we found the effect of different coal, coal bed height and different heating time on the removal of the moisture.