Why does flue gas recirculation decrease flame temperature?

By recirculating part of the flue gases, NOx emissions can be significantly reduced. The injection of the flue gases increases the ballast of the gases not involved in combustion, thereby lower the flame temperature.

What temperature is flue condensate?

around 135°F.
Flue gas will form and condense on a heat exchanger and in the boiler stack when it falls below its dew point, and this occurs when the return water temps of the system are around 135°F.

What is FGR in boiler?

Flue Gas Recirculation (FGR) is a powerful nitrogen oxide (NOx) control technique that significantly reduces NOx emissions by recirculating flue gases from the boiler exhaust duct into the main combustion chamber.

How do I reduce NOx in my boiler?

Water or steam injection can be utilized to reduce NOx levels. By injecting water or steam into the flame, flame temperatures are reduced, thereby lowering thermal NOx formation and overall NOx levels.

What is the primary objective of fuel gas recirculation system?

About Flue Gas Recirculation Systems The goal of flue gas recirculation systems is to gradually reduce the amount of NOx emissions. Flue gas from the stack is sent back into the combustion chamber through the burner, which helps to cool down the flame peak temperature and slow down reactions in the combustion chamber.

What is a FGR fan?

By B Wilson | June 19, 2019. Flue Gas Recirculation (FGR) is the process of taking a portion of the flue gas from a combustion process and recirculating it back through a boiler or burner. When the process is used in internal combustion engines it is commonly referred to as exhaust gas recirculation (EGR).

What is the dew point of flue gas?

The acid dew point temperature depends on the levels of reactants present in the flue gas. It generally lies in the range 100-150°C.

How do you reduce the temperature of a gas flue?

The temperature of the flue gas leaving the boiler is commonly reduced in an air preheater (APH) when the sensible heat in the flue gas leaving the economizer is used to preheat combustion air. Preheating of combustion air has a significant positive effect on boiler efficiency.

What is a gas recirculation fan?

Gas recirculation fans (FGR) are typically used in power plant boilers to reduce the flue gas pollution content in the gases exhausted from thermal combustion processes. Flue gas re-circulation is a highly effective technique that significantly reduces the Nitrogen oxide (NOx) emissions from burners.

How do you remove NOx from flue gas?

A method was proposed to remove NOx and SO2 in flue gas by using the sulfinyl functional group as a catalyst. Ozone is introduced into the flue gas to oxidize NO. Soluble NO2 and SO2 reacted with ammonia to form ammonium sulfate and ammonium nitrate, which were the raw material of the compound fertilizer.

Does NOx increase with temperature?

The concentration of NOy increases significantly with temperature (Fig.

How does EGR lower combustion temp?

EGR systems recycle a portion of the exhaust gas back into the combustion chamber, where it combines with fresh intake air. This lowers the amount of Oxygen and increases the water vapour content to the combustion mixture which reduces the peak combustion temperature.