Coal grinding mill is a machine that crushes and grinds coal into pulverized coal. It is an important auxiliary equipment of pulverized coal furnace.
The ball mill is a horizontal cylindrical rotating device driven by external gears. Mate
rial from the feed device enters the mill evenly through the feed hollow shaft helix. Installed with steel balls of different specifications, the centrifugal force generated by the rotation of the cylinder will bring the steel ball to a certain height and then drop, which will have a heavy impact and grinding effect on the material. The powder is discharged through the discharging grate to complete the grinding operation.
Crushing principle of coal grinding mill Low-speed coal grinding mill It is mainly drum ball mill, generally referred to as coal grinding mill. It is a rotating cylinder or conical drum with steel balls in it. The speed of the drum is 15-25 rpm. The steel ball in the working cylinder continuously impacts and extrudes the coal block, and grinds the coal block into pulverized coal. Then the coal is dried by hot air into the drum and the pulverized coal is sent out. After separation by the separator, the pulverized coal with a certain size is sent into the pulverized coal bin or directly into the pulverized coal burner. Steel ball mill is bulky, high power consumption and noisy, but it is suitable for grinding hard anthracite because of its wide range of adaptability and reliable operation.
Medium-speed coal grinding mill The speed ranges from 50 to 300 rpm, and there are many kinds. Common mills are flat disk mill, bowl mill, E-type mill and roller mill. Their common feature is that the grinding parts are composed of two groups of relatively moving grinding bodies. Coal blocks are crushed between the surfaces of the two groups of grinding bodies. At the same time, the hot air flowing into the coal grinding mill dries the coal and sends the pulverized coal to the separator at the upper part of the grinding zone. After separation, a certain size of pulverized coal is brought out of the grinding with air flow, and the coarse pulverized coal is regrinded in the grinding zone. Medium-speed coal grinding mill has obvious advantages, such as compact equipment, small occupation of land, low power consumption (about 50-75% of coal grinding mill), low noise, light and sensitive operation control, etc. However, its structure and manufacture are complex, its maintenance cost is high, and it is not suitable for grinding harder coal. Bowl mill is widely used in large capacity coal-fired boilers.
High-speed coal grinding mill The rotational speed is 500-1500 rpm, mainly composed of high-speed rotor and grinding case. Common are fan mill and hammer grinding. In fan mill, coal blocks are ground by high-speed impact of high-speed rotor, collision of grinding shell and collision of coal blocks with each other. The coal grinding mill and pulverized coal separator are integral, simple in structure, compact and low in initial investment. They are especially suitable for Grinding High Moisture Lignite and bituminous coal with high volatility and easy grinding. Fan mill is not suitable for grinding hard coal because of its large wear and tear, and its continuous running time is shorter than other coal grinding mills.
