Which type of air is directly involved in the combustion process at the burner?

The combustion process at the burner primarily involves primary air. Primary air refers to the initial air that is mixed with the fuel to facilitate combustion. This is crucial for creating the right mixture of fuel and air to ignite and sustain a flame. The effectiveness of combustion largely depends on the proper ratio of primary air to fuel, as this influences the efficiency and completeness of the combustion process.

While secondary air also plays a role in the overall efficiency of combustion, it is introduced after the initial combustion has begun and helps to optimize the burn by promoting better mixing of gases and completing the combustion process. Flue gas, on the other hand, is the byproduct resulting from combustion and does not contribute to the combustion itself. Combustion air is a more general term that can refer to any air used in the combustion process, but primary air specifically refers to the air that is immediately mixed with the fuel at the burner. Thus, the focus on primary air is essential because it directly contributes to the initiation and stability of the combustion reaction at the burner.