What is the main function of a mechanical draft system in a boiler?

The main function of a mechanical draft system in a boiler is to control airflow and maintain the combustion environment. This system plays a crucial role in regulating the amount of air that enters the combustion chamber, ensuring that there is an adequate supply of oxygen for the fuel to burn efficiently. By optimizing the air-to-fuel ratio, the mechanical draft system helps achieve complete combustion, which is essential for maximizing energy efficiency, minimizing emissions, and maintaining safe operating conditions.

In providing the correct amount of air, the system also supports consistent boiler operations, facilitating stable combustion processes. A well-functioning mechanical draft system contributes to effective heat transfer and helps in managing flue gases, which is vital for the overall performance of the boiler.

The other choices describe functions that are not associated with a mechanical draft system. Supplying water to the boiler is the role of feedwater systems, while storing excess steam relates to steam drum functionalities. Preventing overheating is managed through various safety mechanisms, including temperature control and feedwater management, rather than through the draft system. Understanding the specific roles of different boiler components is important for power engineers to ensure safe and efficient operations.