Why is secondary air necessary in hand-fired boilers?

Secondary air is vital in hand-fired boilers because it plays a crucial role in the effective combustion of fuel by ensuring that combustible gases are burned thoroughly. When fuel is burned, particularly solid fuels like wood or coal, volatile gases are released. Secondary air provides the necessary oxygen for these gases to ignite and burn completely, leading to a more efficient combustion process. This helps to reduce smoke and unburned fuel, which can contribute to emissions and waste.

By introducing secondary air, the combustion temperature can also be maintained at optimal levels, maximizing heat production and improving the overall efficiency of the boiler. This is especially important in hand-fired boilers, where the manual loading of fuel can lead to variations in the combustion process. Thus, the presence of secondary air is critical for ensuring clean and efficient burning of the fuel.