NOx Control for Roof-Fired Boilers

Low NOx Burners with Separated Parallel-Flow Over-Fire Air

Roof-fired boilers inject coal and air downward into the furnace, where they combust and eventually turn upward to exit through the convective sections. Very few roof fired boilers were constructed, and no off-the-shelf NOx control technology existed for them. Working with Duquesne Light, Steag Energy Services (formerly ESA) engineers developed a low NOx burner and a Parallel Overfire Air system for roof fired furnaces.

The low NOx burner system consists of selectively blocking coal nozzles to produce fuel rich and fuel lean zones.

The Parallel Separated Overfire Air system is designed to divert a portion of the combustion air away from the burners and introduce it parallel to the main combustion flow. Introduction of the diverted air parallel to the main stream delays mixing and completion of combustion, allowing for NOx generation to be controlled.

The roof-fired NOx control technologies were refined with Steag Energy Services's (formerly ESA) CFD modeling.

This technology is registered under US Patent Numbers 5,694,869 and 5,546,874.

<< Back to NOx Control