The primary goal of this project is to develop and demonstrate an advanced in-furnace NOx control technology capable of achieving an emission rate of 0.10 lb/MMBtu while burning high-volatile bituminous coal. Babcock & Wilcox Company (B&W), in collaboration with American Air Liquide, will evaluate the technology at pilot-scale in wall- and cyclone-fired boilers.

The NOx control technology is based on a “layered” strategy that combines deep air staging, continuous corrosion monitoring, advanced combustion control enhancements, and a proprietary combustion technique using oxygen injection. The accompanying figure shows a schematic of the layered process, which includes three zones: main combustion, reburn, and burn-out. The stoichiometric ratio (SR) in the main combustion zone will be varied from 0.8 to 1.1. The reburn zone features oxygen-enhanced combustion of the re-burn fuel and flue gas recirculation (FGR). The burnout zone utilizes overfire air (OFA) to complete combustion. To evaluate the oxygen injection process, wall- and cyclone-fired pilot-scale testing will be conducted at B&W's 5 million Btu/hr Small Boiler Simulator (SBS) facility. Oxygen will be injected at various locations in the combustion zone and data gathered by optical sensors will be used to optimize the combustion process. Corrosion monitoring sensors will assess potential water wall wastage that could occur under severe operating conditions. Testing will also evaluate the effects of oxidizer composition, extent of deep air staging, and overall excess oxygen level on combustion behavior, heat transfer characteristics, and emissions levels. Finally, results from the pilot-scale testing will be used to design and prepare a cost estimate for a full-scale version of the technology.