Combustion air is the air that is used to actually burn fuel. Without combustion air, which is normally forced into the furnace, combustion is impossible. The efficient operation of today’s power plant hinges largely upon accurate and repeatable measurement and control of various air inputs to the boiler such as Primary air, Secondary air, Overfire air, individual burners, and flue-ga... https://leomi.in/applications/gas-type/combustion-air/