China (Mainland)
The Introduction of Kefan Coal Mill ：
Coal mill also called coal pulverzier or coal powder mill is that grinding mill used in coal mining industry and thermal power plant, such as vertical coal mill. And in general, vertical mill includes mineral series and coal series. The first series grinder can be widely used in cement making, power, metallurgy, chemical, ore industries. And the vertical coal mill also called coal grinder is the most used machine for coal grinding according to our mining experience. In some cases, coal mill is not just one grinder mill, it will include some optional equipment such as vibrating feeder, vibrating screen, belt conveyors and so on to finish the coal milling process. So, coal mill is also used widely in many industries besides coal mining.
In coal-fired power plants coal mills are used to pulverize and dry to coal before it is blown into the power plant furnace. The coal is feedinto the coal mill through a central inlet pipe where gravity is used to lead the coal to the bottom of the mill, where the grinding table and some heavy rollers pulverizes the coal to particles. The primary air flow to the furnace is fed through the mill, with the purpose of heating and lift the coal particles out of the mill and into the furnace.
Coal Mill Pulverizer Working Principle:
Raw coal is fed through a central coal inlet at the top of the pulverizer and falls by gravity to the rotating grinding table, mixing with classifier rejects returned for re-grinding. Centrifugal action forces the coal outward to the grinding ring where it is pulverized between the ring and three grinding rollers. Grinding load, transmitted from the tension rods through the loading frame to the roller assemblies, holds the rollers in contact with the grinding ring. The rollers adjust vertically as the depth of the coal load increases or decreases.
A nozzle ring on the outside perimeter of the grinding ring feeds primary air to the pulverizer. Pyrites and tramp metal fall through the nozzle ring openings to be scraped into a rejects hopper.
A stream of low-velocity air carries the particles of pulverized coal upward where they enter the classifier inlet vanes. Fine particles travel to the burners in the primary air stream, but the larger, heavier particles are returned to the grinding zone for further pulverization.