The use of a varied percentage of the flue gases to reduce the burner flame temperature, injecting them into the secondary air, represents “dilution” technology whose scope is to obtain a “softer” and “colder” flame by decreasing the excess air.

By reducing the concentration of oxygen, the flame temperature is also reduced and consequently so is the formation of NOx originating from heat.

Another effect of flue gas recirculation is to reduce the CO levels to their minimum as thanks to its re-emission in the cycle an almost complete combustion process is obtained.

Naturally, precautions have to be taken to ensure flame stability as well as for the presence of particles inside the burner that is then specially filtered.