Coal Pulveriser in Power Plants: Function, Types, and Maintenance
Coal pulverisers play a critical role in thermal power plants by grinding coal into fine powder, ensuring efficient combustion in boilers. This process enhances fuel efficiency, reduces emissions, and improves overall plant performance. Understanding the working principles, types, and maintenance of coal pulverisers is essential for power plant operators and engineers.
Function of Coal Pulverisers
The primary function of a coal pulveriser is to crush and grind raw coal into a fine powder with a consistency similar to talcum powder. This powdered coal is then blown into the boiler furnace, where it burns more efficiently than lump coal. The finer the coal particles, the better the combustion efficiency, leading to higher heat generation and lower unburnt carbon residues.
Types of Coal Pulverisers
Several types of pulverisers are used in power plants, each designed for specific coal properties and operational requirements:
1. Ball Mill Pulveriser – Uses steel balls to crush coal inside a rotating drum. Suitable for hard coals but consumes more power.
2. Vertical Spindle Mill (Bowl Mill) – Features grinding rollers that press against a rotating bowl-shaped table. Common in modern power plants due to its energy efficiency.
3. Impact Mill (Hammer Mill) – Utilizes high-speed hammers to pulverize coal by impact force. Best for softer coals but requires frequent maintenance due to wear and tear.
4. Attrition Mill – Relies on rubbing action between two surfaces to grind coal particles finely but is less common in large-scale power plants.
Key Components of Coal Pulverisers
A typical pulveriser consists of:
- Grinding Elements: Rollers or balls that crush coal mechanically.
- Classifier: Separates fine particles from coarse ones for recirculation.
- Primary Air Fan: Supplies hot air to dry raw coal and transport powdered fuel into the boiler furnace.
- Drive System: Includes motors or gearboxes that rotate grinding elements at optimal speeds.
Maintenance Challenges & Best Practices
Regular maintenance ensures smooth operation and prolongs equipment life:
- Wear & Tear: Grinding components degrade over time; periodic inspection prevents unexpected failures.
- Coal Quality Impact: High moisture or abrasive impurities accelerate wear—proper drying & screening mitigate this issue.
- Vibration