The coal mill needs to be started in the power plant, what are the starting conditions of the coal mill?


Release time:

2021-08-06

The coal grinding process is the process in which coal is shredded and its surface area continues to increase. To add new surface area, the binding forces between solid molecules must be overcome and therefore energy consumed.

The coal grinding process is the process in which coal is shredded and its surface area continues to increase. To add new surface area, the binding forces between solid molecules must be overcome and therefore energy consumed. Coal is ground into pulverized coal in the coal mill, mainly by crushing, crushing and grinding. Among them, the crushing process consumes the most energy. The crushing process is the most energy-intensive. All kinds of coal mills have the above two or three methods in the milling process, but the main one depends on the type of coal mill.
  
There are many types of coal mills, and they can be divided into three types according to the speed of the working parts of coal grinding, namely low-speed coal mills, medium-speed coal mills and high-speed coal mills.
  
Mainly for drum type steel ball mill, generally referred to as steel ball mill or ball mill. It is a rotating cylindrical or tapered drum with steel balls inside. The speed of the drum is 15~25 rpm. During work, the steel balls in the cylinder continuously hit and squeeze the coal blocks, grinding the coal blocks of the coal mill into pulverized coal. Then the coal is dried by the hot air passing into the drum and the pulverized coal is sent out, and after being separated by the separator, the pulverized coal of a certain particle size is sent to the pulverized coal silo or directly sent to the pulverized coal burner. The steel ball mill is bulky, high power consumption and high noise; However, it has a wide range of adaptability to coal types and reliable operation, which is especially suitable for grinding hard anthracite.
  
Mill start sequence control 2.1 Select the mill start sequence from DCS manual or automatic master control is valid, before the DCS manual or automatic master start sequence instruction is issued, check the coal mill sequence start must meet the following.
  
(1) Reasonably select the starting sequence of the coal mill. When warming the coal mill, warm the B and E mills first, and after the coal mill reaches the starting conditions, start the B coal mill or E coal mill to run to ensure that the heat load of the furnace is concentrated and evenly distributed. (2) Carefully adjust the water supply. After the boiler ignition.
  
(2) When starting, the order of coal mill starting is D, B, A, C, F, E. After the D coal mill is started, the pressure of the pulverized pipe at the outlet of the running coal mill is greater than the pressure of the purge mother pipe, and the pulverized coal in the outlet pulverized pipe of the running coal mill begins to pour through the purge damper.
  
Before starting the coal mill, start the lube oil system. When the oil temperature of the oil pool of the reducer is lower than 25 °C, the electric heater starts to work. When the oil temperature of the oil pool is higher than 28 ° C, cut off the heater. When the oil supply pressure is greater than 0.13MPa, the oil temperature of the reducer reaches 28 °C, push.
  
In order to better understand the overall structure of the coal mill, attached: see the schematic diagram of the double-in, double-output ball mill 2, the starting sequence of the coal mill 2.1 Select the start sequence of the coal mill from the DCS manual or automatic master control is valid, and start the manual or automatic master start in the DCS. Grinding coal.
  
After the No. 2 furnace of Dagang Power Plant was put into operation, there was always a problem of overheating of the superheater and reheater pipe wall during the start-up of the coal mill. According to the flue gas flow, the order is wall radiant reheater--- split screen superheater--- rear screen superheater--- screen reheater --- end.
  
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