In boiler operation, what is the purpose of primary air?

The purpose of primary air in boiler operation is to provide combustion support. Primary air is the air that is introduced into the combustion chamber along with the fuel and is essential for sustaining the combustion process. It helps to mix with the fuel and supports the ignition and burning of the fuel, which is crucial for creating the necessary heat and steam generation in the boiler.

In efficient combustion, the right amount of air must be mixed with the fuel; if there's insufficient primary air, combustion would be incomplete, leading to the production of smoke, carbon monoxide, and wasted fuel. Conversely, too much air can cool the flame and reduce efficiency. Therefore, proper management of primary air is vital for optimal boiler operation and efficiency.

The other options, while relevant in a broader scope, do not specifically describe the primary function of primary air in combustion. Preheating fuel, regulating pressure, and cooling the system all pertain to different aspects of boiler operation or may involve secondary air, but they do not directly relate to the primary function of supporting combustion.