- Pulverized Fuel Firing Definition: Pulverized fuel firing involves grinding coal into fine particles and spraying them into the combustion chamber for efficient burning.
- Improved Thermal Efficiency: Pulverized coal increases the surface area for combustion, leading to higher thermal efficiency and faster combustion rates.
- Fuel Versatility: Lower grade coal can be effectively used once pulverized, making the system flexible.
- Quick Load Response: The system can quickly adjust to changing loads, providing stability to the electrical grid.
- Higher Costs and Safety Risks: Although efficient, the system has higher initial and running costs, and requires careful handling to prevent fire hazards and explosions.
The solid-fuel firing method can’t handle load fluctuations well. It’s also not stable enough for large thermal power plants. The flue gases have a lot of ash, making it hard to separate from the exhaust. So, non-pulverized coal firing isn’t practical for large boilers. The main drawback is that it doesn’t burn the fuel completely, reducing thermal efficiency.
Pulverized fuel firing is widely used today because it greatly improves the thermal efficiency of solid fuel. In this system, coal is ground into fine particles, called pulverization. These particles are sprayed into the combustion chamber with hot air, known as “primary air,” which must be dry. Additional air, called “secondary air,” is added to complete combustion. The thermal efficiency of the system depends on how fine the coal is crushed. This method is ideal for coal that isn’t suitable for solid fuel firing.
Advantages of Pulverized Fuel Firing
- Pulverizing coal increases its surface area, boosting thermal efficiency. This leads to a faster combustion rate and reduces the need for secondary air. It also lessens the load on air intake fans.
- Comparatively lower grade coal can also be utilized as efficient fuel once it gets pulverized.
- Faster combustion rate makes the system more responsive to the changing load as the combustion can easily and quickly be controlled.
- There is no clinker and slagging problems in pulverized coal firing system.
- More considerable amount of heat is released compared to that of the same physical size of the solid firing system.
- Starting of the pulverized coal firing system is quicker than that of the solid firing system. Even its operation can be launched from a cold condition very rapidly and efficiently. This feature of the boiler system is essential for electrical grid stability.
- Another essential feature of the pulverized firing system is that it does not have any moving parts inside the combustion chamber which gives it long trouble free life.
- The ash handling is more straightforward in this system since there is no solid ash.
Disadvantages of Pulverized Coal Firing
- The initial investment in pulverized coal firing system is more compared to solid firing system.
- The running cost is also higher.
- The pulverized coal produces fly ashes.
- Removal of ash grain from the exhaust gases is always expensive as it requires an electrostatic precipitator.
- There may be a possibility of the explosion like the coal burns like a gas.
- The storage of pulverized coal requires particular attention always being protected from the fire hazards.
