AIR POLLUTION CONTROL Over-Fire Air Systems

OVER-FIRE AIR SYSTEMS

Fuel Tech's Over-Fire Air (OFA) system deeply stages combustion for enhanced NOx reductions. Additional NOx reductions, beyond low NOx burners of 35%-50%, are possible on wall, tangential, turbo or cyclone fired boilers on all fuel types. Unique port design enhances mixing to limit impact on combustion efficiency.

Combustion air is diverted from the burners to create a fuel rich zone in the lower furnace. Fuel bound nitrogen conversion to NO is inhibited on coal and oil fired boilers. Peak flame temperatures are reduced on gas fired boilers to limit thermal NOx formation. A high momentum air stream intersects burner flames in the upper furnace to complete combustion prior to the boiler convective section.

The OFA port is shaped by a refractory "boot" with combustion air fed through a 310 SS duct for long life. Automated damper controls allow for tuning through the load range.