In a vertical coal mill, drying, grinding, and separating/classifying of coal can be done simultaneously. Hence, production and energy efficiency is higher than those of a tube mill. The vertical coal mill works as follows:
- Wet coal is feed from the upper part or side of the mill onto the rotating table.
- It was then crushed and ground by the pressing of the steel roller.
- Fine coal particles are dried and swept away into the separator by a high velocity of hot air flow from the bottom of the mill.
- Separated fine coal particles are captured by a bag filter and used as fuel.
Reduction of electricity consumption for coal grinding: 20-25% compared with tube mill.
Productivity: higher compared with tube mill.
Thermal monitoring system or thermal control system are required in order to prevent coal firing. This technology is related to vertical mill applied to other process.
Ministry of Economy,Trade and Industry, Japan