TECHNOLOGIES TO REDUCE NOX
“Mild” combustion: flameless
“Flameless” combustion occurs when the temperature of the fuel is above the self-ignition point, or in general above 750°C and the fuel is injected directly into the furnace, without mixing it with the oxidizer, at levels of turbulence and speed such as to facilitate mixing with the burnt gases. An oxidation reaction then occurs outside the visible range, but which still produces thermal energy released in the oven.
The elimination of the flame significantly reduces the formation of NOx as the greater homogeneity of temperatures and distribution of oxygen that is generated , slows down the reaction with atmospheric nitrogen. Furthermore, with the elimination of the “flame front” (the area of demarcation between reagents and combustion products) the main area of creation of NOx itself is eliminated. Part of the NOx formed is finally directly brought back into the reaction and re-oxidized.
Inside the oven
This is what happens into the furnace switching from flame to flameless mode bypassing the mixer and injecting fuel directly into the chamber by lateral slots.
Temperature profiles
Temperature profiles switching from flame to flameless: it is possible to see the actual temperature homogeneity.
By pass Valve
Typical ESA bypass valve with pneumatic actuator to switch from flame to flameless mode, which equips long flame refractory burners but also SIC high velocity burners.
Flameless on Self Recuperative burner
Sample of special configuration with specific flameless nozzle and double gas adjuster valve to regulate the fuel flow.
Flameless on recuperative burner
Flameless on Regenerative burner
On all models of long flame, recuperative, regenerative and self-regenerating burners, the flameless option is available with a particular kit and a pneumatic bypass valve.
A VERSATILE TECHNOLOGY
ESA flameless concept, easy and effective!
ESA uses a single pneumatic valve for flameless combustion, its own simple and effective concept for all recuperative, self-recovery, self-regenerating hot air models, even with pure hydrogen.
FLAMELESS FAQ
It becomes mandatory to deactivate the flame detection system, as it would be completely useless and/or deactivate the ignition system: combustion will take place anyway.
In our experience, we observe a slight decrease in efficiency which we attribute to the lack of the radiant component of the flame. However, since flameless is used specifically to use air at very high temperatures, recovering otherwise wasted energy, we can consider this loss of efficiency to be negligible in the context.
It is not only possible but often absolutely necessary to avoid expensive urea systems.
The most common contraindication is loss of turndown.
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