What are the three types of draft used in power plants?

In power plants, the types of draft that are primarily discussed include natural draft, forced draft, and induced draft. Each type of draft relates to how air or combustion gases are moved through the system.

Natural draft relies on the buoyancy of hot air, which causes it to rise and draws in fresh air from the surrounding environment. This is a passive method of moving air, dependent solely on temperature differences and the design of the stack or chimney.

Forced draft systems use fans or blowers to push air into the combustion area, ensuring a consistent supply of oxygen for the combustion process. This method enhances combustion efficiency and can adjust airflow to meet varying operational demands.

Induced draft, on the other hand, involves fans that draw air through the combustion area and expel the exhaust gases outdoors. This approach improves the efficiency of the exhaust system and helps maintain optimal pressure within the furnace.

The provided choice regarding natural, forest, and induced does not accurately represent the established terminology used within the context of power plants concerning draft types, as "forest" does not apply. The other options similarly contain inaccuracies related to either terminology or miss out on clearly distinguishing between all three key draft types typically relevant to steam power generation.