What is the primary reason for using a controlled rate of coal supply in boilers?

Using a controlled rate of coal supply in boilers is crucial for promoting efficient combustion. When the supply of coal is regulated, it ensures that the combustion process has the right balance of fuel and air. This balance is essential for achieving complete and efficient combustion, which not only maximizes energy output but also minimizes the production of unburned fuel and harmful emissions.

Efficient combustion contributes to improved boiler performance, as it helps maintain optimal temperatures and pressures within the system. This ultimately leads to a reduction in fuel consumption and operating costs, creating a more economical and environmentally friendly boiler operation.

Other options might touch on important boiler operation aspects, such as minimizing pollution in a broader context or enhancing repair processes. However, these are not directly linked to the core principle of supplying coal at a controlled rate, which primarily focuses on achieving efficient combustion.