What device is commonly used to preheat combustion air?

The correct choice is the premixer, as it is specifically designed to mix the fuel with combustion air before combustion occurs. This device helps to ensure that the fuel is thoroughly mixed with the air, enhancing the efficiency of the combustion process and enabling more complete burning of the fuel.

Preheating combustion air can help improve efficiency, reduce emissions, and optimize the combustion process overall. However, while other options like a recuperator or dampers might play roles in heat recovery or controlling airflow, they do not primarily function to mix or preheat the combustion air in the same targeted way a premixer does. The atomizer is related to fuel preparation rather than directly preheating air. Thus, the premixer stands out as the most relevant device for this specific task.