Air swept coal mill

Application

Air swept coal mill, or air swept pulverizer, is major grinding equipment for pulverized coal production in power plant, cement plant. Hot air stream (heated by air preheater) from primary air fan could take away pulverized coal when passing through coal mill, and dry the fine particles at the same time. Air swept coal mill is low speed ball mill with rotation speed 15-25rpm.

Structure

Air swept ball mill mainly consists of feeding & discharge system, hollow shaft, rotating cylinder filled with steel balls, gear ring, transmission system (high voltage motor, reducer, trunnion, pinion), lubrication system, control system, etc. Hollow shaft is made of cast steel. Cylinder inner wall and hollow shaft is lined with wearing resistant plates to protect themselves.

Working principle

During cylinder rotation, cascading balls fall down. Coal blocks are pulverized by three forms of motion: impact, extrusion, grinding. Hot air from PAF exchanges heat with pulverized coal and takes them out of air swept mill to storage silo.

Advantages

1. Stable operation, reliable performance, easy maintenance.
2. Wide adaptability for coal types, particularly suitable with hard anthracite.
3. Suitable with coal with abrasion index Ke >3.5. High abrasion loss, but steel balls can be charged without shutdown.
4. Not sensitive to iron block, wood block, rock.
5. High drying capacity. It could pulverize coal with high moisture content when compared with medium speed coal mill.

Air swept coal mill is widely used for pulverized coal preparation system in power generation, metallurgy, chemical, cement plant, especially suitable for pulverizing system with intermediate storage bunker.