subject: Do You Need Coal Mill To Grind Your Coal? [print this page] 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 feed
into 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. If the the particles are too heavy they will drop to the
bottom of the mill and will be pulverized once more. The coal
particles are heated to 100 degrees Celsius. The temperature of the
primary air flow is manipulated for controlling this temperature
measured as a temperature in the mill at the exit. The primary air
temperature is controlled by controlling the position of an air mixer,
which mixes heated outside air and cold outside air.
In order to control the energy production of the plant, the coal flow
into the furnace is an very important factor. Unfortunately, it is not
possible to measure the coal flow from the coal mill to the
furnace. The coal flow out of the mill is often estimated based on the
incoming coal flow. In case of a fault in the coal mill the plant
operator would need to take accommodating actions as fast as
possible. Fault detection in the coal mill is consequently important.
In this example two possible faults are present. The first is a
blocking of the coal inlet pipe, which result in a stopped incoming
coal flow. The second is a position fixing of the air mixer.
Coal mill is an efficient tool for grinding coals into fine powder in coal mining industry. According to its fineness and working principles, we divide coal mill into coarse power coal mill and fine coal mill. Coarse powder mill is a kind of new high-tech milling machine to meet the requirements of coarse powder processing customers. It is the ideal equipment to replace Raymond mill, ball mill, and other traditional mill which only process fine coal powder materials.
