What is primary and secondary air in furnace?

The primary air is heated up to about 170°C by means of a heat exchanger with the exhaust gas. The secondary air is the postcombustion air injected into the upper part of the combustion chamber and is necessary for completing the combustion process.

What is primary air in furnace?

Definition of primary air : air admitted to the fuel stream or area ahead of the combustion zone in a burner or furnace.

What is secondary and primary air?

Primary air pollutants: Pollutants that are formed and emitted directly from particular sources. Examples are particulates, carbon monoxide, nitrogen oxide, and sulfur oxide. Secondary air pollutants: Pollutants that are formed in the lower atmosphere by chemical reactions.

What is secondary air furnace?

Secondary air is fed above the burning fuel via ring-shaped nozzles to ensure full conversion of the flue gas. Additional air is fed into the system via the fall pipe to prevent fire from backing into the fuel container.

Why do we use secondary air?

WHY IS A SECONDARY AIR SYSTEM USED?: BASIC PRINCIPLES This system further lowers the HC and CO values during the cold start phase when the catalytic converter is not yet active. A conversion rate of over 90 percent is achieved using a 3-way catalytic converter in stoichiometrically operated gasoline engines.

What happens to the flame if there is too much primary air?

The secondary air will control the flame pattern but too much primary air will create a smaller brighter flame that will not give off as much heat causing you to burn more fuel.

What is primary secondary and tertiary air?

The primary air gives the initial ignition oxygen, the secondary air allows the higher hydrocarbon or char to burn, and the tertiary ensures the delayed combustion process purposely introduced by designers to reduce NOx level.

Where is the secondary air induced into the furnace?

combustion chamber
Atmospheric burners are the most common type of gas burner. A pilot light, hot surface ignitor, or sparking electrode will ignite the mixture. Secondary air inside the combustion chamber around the flame gives oxygen for almost complete burning.

What is primary air fan?

Primary air fans are one type of fan that can be used in certain boilers. They are often used as an alternative to pulveriser blowers on coal-fired boilers for power generation. Primary air fans provide high-pressure air to the boiler system, which enters it through the APH.

What is a secondary air system?

Secondary-air systems have been successfully employed to reduce such cold starting emissions. To reduce the level of these pollutants, ambient air with a high oxygen content (“secondary-air”) is injected into the exhaust manifold directly downstream of the exhaust valves during the cold starting phase.

What is the difference between primary air and secondary air?

Primary air provides a percentage of the combustion air, but more importantly, controls the amount of fuel that can be burned. Secondary air improves combustion efficiency by promoting the fuel to burn completely. Power burners generally do not require secondary air.

What is primary air in a furnace?

Air which is introduced into a furnace (in addition to the primary air which enters either as a mixture with fuel or as blast underneath a stoker) above or around the flames to promote combustion. Air already in an air-conditioned space, in contrast to primary air which is introduced into the space.

What are the primary and secondary air inlets in steam boilers?

Steam boilers having an external furnace are generally provided with both Primary ( pa fans ) and Secondary air inlets and both play an important role in the combustion of fuel. Primary air is generally the basic amount of air required for complete combustion of fuel and it depends upon the composition and quantity of fuel required by the boiler.

What is the role of primary and secondary air in combustion?

Both Primary air and Secondary air have an important role to play in fuel combustion and must be provided in different ratios according to the fuel quantity. For combustion of any fuel to take place, 3 basic ingredients are needed: