Slag Rotary Dryer
Description
The air-swept coal mill is ideal equipment for grinding and simultaneously drying coal powder. It is designed to process coal, coal gangue and other materials, and is energy-saving and environmentally friendly. The fineness of the pulverized coal is more than 85% through a 200 mesh sieve, while the moisture of the finished product is below 2%.
The equipment is widely used in power generation, metallurgy, mining, the cement industry, building-materials production, the chemical industry and other fields. It is ideal equipment for grinding pulverized coal used in industrial furnaces, rotary kilns and other thermal units, and is also the main equipment of the pulverized-coal preparation system.
The mill integrates the functions of material crushing, grinding and pneumatic conveying, providing an integrated process of drying and grinding the coal powder. According to the rotational speed of the working parts, coal mills are divided into low-speed, medium-speed and high-speed mills. The ball-type coal mill is also one of these types of equipment.
The main units of the equipment include the feeding device, the main bearing, the rotating part, the drive device, the material feeding and discharging devices, the high-voltage starting system and the lubrication system.
The working principle is as follows: the raw material enters the mill through the feeder and exchanges heat with the hot air supplied through the air duct. As the drum rotates, the lumps of coal are crushed and ground, and the finished fine coal powder is carried out by the induced-draft fan.
Structure
The air-swept coal mill mainly consists of the feeding device, the main bearing, the rotating part, the drive device, the discharge device, the high-voltage starting system and the lubrication system.
The feeding device adopts a louvered structure with inclined air admission, which enhances the heat-exchange capacity of the air-swept coal mill and effectively prevents material clogging at the inlet of the coal mill.
The rotating part of the mill adopts an air-swept structure with a drying chamber, so that the mill has strong adaptability to the moisture of the raw coal. In the grinding chamber, stepped liners, double-stepped liners, corrugated liners and other combined arrangements are used in sequence, which improves the grinding capacity of the mill.
The drive is usually of the peripheral type: the electric motor drives the mill drum to rotate through a reducer and a pair of large and small gears.
In addition, the structure includes the main bearing supporting the drum, the discharge device for discharging the coal powder, the high-voltage starting system to ensure smooth start-up of the equipment, and the lubrication system to ensure the normal operation of all moving parts.
Working principle
The working principle of the air-swept coal mill is that it can both grind finely and dry. The feeding device delivers the raw coal into the inlet device, while hot air at a temperature of about 300 ℃ enters the mill through the air duct to pre-dry the raw coal.
After the coal enters the mill drum, it is crushed and ground. In the rotating drum, the lining plates lift the grinding media to a certain height and then let them drop, using their impact and friction energy to crush and grind the coal. During this process, the coal continuously exchanges heat with the hot air.
The resulting fine coal powder, together with the spent hot air, is drawn out of the mill by the induced-draft fan. The gas-powder mixture passes through a separator or classifier, where the off-spec coarse powder is separated out and returned to the mill for re-grinding.
Technical features
The air-swept coal mill is characterized by high grinding efficiency and relatively low energy consumption. The equipment can operate continuously and has high productivity. The metal consumption per unit of product is low, and the maintenance costs are relatively low.
The structure of the equipment is relatively simple and has a drying function. Thanks to the air-swept structure with a drying chamber, the mill adapts well to different moisture levels of the raw coal. The feeding device adopts a louvered structure with inclined air admission, which enhances the heat exchange inside the mill and helps prevent clogging at the inlet of the coal mill.
The air-swept coal mill provides finer and more uniform grinding of the material. The equipment features low vibration and noise, good sealing and no dust spillage to the outside.
Compared with ball mills of the same size, the air-swept coal mill usually has higher productivity, provides finer grinding and a larger specific surface area of the finished product.
