Southern Research Institute is developing a validated tool or methodology to accurately and confidently design and optimize biomass-cofiring systems for full-scale utility boilers to produce the lowest NOX emissions and the least unburned carbon. The computer model will be validated through an extensive set of tests at the 6 MMBtu/hr pilot combustor in the Southern Company/Southern Research Institute Combustion Research Facility. Full-scale demonstration testing can be compared to the model for further validation.

The project is designed to balance the development of a systematic and expansive database detailing the effects of cofiring parameters on NOx formation with the complementary modeling effort that will yield a capability to predict, and therefore optimize, NOx reductions by the selection of those parameters. The database of biomass cofiring results will be developed through an extensive set of pilot-scale tests at the Southern Company/Southern Research Institute Combustion Research Facility. The testing in this program will monitor NOx, LOI, and other emissions over a broad domain of biomass composition, coal quality, and cofiring injection configurations to quantify the dependence of NOx formation and LOI on these parameters. This database of cofiring cases will characterize an extensive suite of emissions and combustion properties for each of the fuel and injection configuration combinations tested.

The complementary process modeling will expand the value of the raw test data by identifying the determining factors on NOx emissions and LOI. Niksa Energy Associates will develop and validate a detailed process model for predicting NOx emissions and LOI from biomass cofiring that builds on a foundation of existing and proven fluid dynamics, reaction kinetics, and combustion products models. The modeling will resolve all major independent influences including biomass composition, coal quality, chemical interactions among biomass-and coal-derived intermediate species, competitive O₂ consumption by biomass- and coal-derived intermediate species and chars, extent of biomass/coal mixing prior to combustion, and mixing intensity during biomass injection.