coal pulverizing mills ppt

# Coal Pulverizing Mills: Types, Working Principles, and Applications

## Introduction to Coal Pulverizing Mills

Coal pulverizing mills are essential equipment in thermal power plants and industrial processes where coal is used as fuel. These mills crush coal into fine powder, increasing its surface area for efficient combustion. Proper pulverization ensures optimal heat generation while reducing emissions. Different types of pulverizing mills are used based on coal properties, plant requirements, and operational efficiency.

## Types of Coal Pulverizing Mills

1. Ball Tube Mills
Ball tube mills consist of rotating drums filled with steel balls that crush coal through impact and attrition. They are commonly used in older power plants and offer reliable performance for medium-speed operations. The crushed coal is dried using hot air before entering the boiler furnace.

2. Vertical Spindle Mills
Also known as bowl mills, these utilize rollers or tires that press against a rotating grinding table. Coal is fed centrally and crushed between the rollers and the bowl. Vertical spindle mills are widely used due to their high efficiency, low maintenance, and ability to handle varying coal qualities.

3. Impact Mills (Hammer Mills)
Impact mills use rapidly rotating hammers to strike coal particles, breaking them into fine powder. These mills are suitable for softer coals but may require frequent maintenance due to wear on hammers and liners. They are often used in industrial applications rather than large-scale power generation.

4. Attrition Mills
Attrition mills rely on grinding elements rubbing against each other to pulverize coal particles. These mills produce finer coal powder but consume more energy compared to other types. They are typically used when ultra-fine pulverization is required for specialized combustion systems.

## Working Principles of Coal Pulverizers

The primary function of a coal pulverizer is to reduce raw coal into fine particles while drying it using hot air supplied from the boiler system. The process involves:
– Crushing: Coal is fed into the mill where grinding elements break it down mechanically.
– Drying: Hot air flows through the mill, removing moisture from the coal particles for better combustion efficiency.
– Classification: Larger particles are separated and returned for further grinding, while fine powder is transported to burners via pneumatic systems or mechanical feeders.

## Applications of Pulverized Coal

Pulverized coal is primarily used in:
– Thermal Power Plants: Enhances combustion efficiency