The Application of Computational Fluid Dynamics in the NOxOUT Process for Reducing NOx Emissions from Stationary Combustion Sources

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services to those desiring control of NOx emissions. Conclusion Computational fluid dynamics modeling has become a powerful process design tool for applying the NOxOUT process. Model refinements have been made to further reduce design uncertainties, thereby increasing the effectiveness and quality of emissions reduction. A major benefit of the NOxOUT Process is the flexibility of injecting treatment chemicals in aqueous form. A wide range of droplet sizes and velocities are possible through simple adjustments in the operating conditions of the injection equipment. This flexibility is best utilized with a detailed knowledge of the conditions within the furnace or duct being treated. The CFD model has provided good estimates of these conditions. A particular benefit of the CFD model has been the ability to predict performance for units not yet in operation. The capabilities of the CFD model are of demonstrated value. State-of-the-art programs and equipment allow modeling to be a routine step in the process design for specific applications. Good estimates of process conditions facilitate nozzle characterization and placement, reducing the amount of time needed for design engineering. The amount of engineering time needed in the field for process start-up and fine-tuning is reduced. In some cases, complete process models have been performed in three to five days, compared with months required for pilot studies with physical models. Substantial refinement of this design tool is underway. With the increasing capabilities of computers, the integration of the chemical kinetics model and the CFD model is becoming feasible. Present plans are to implement a detailed radiation model and combustion model to further improve temperature estimates. Also, improvements in grid placements are being considered to more closely model the geometries of process units. The NOxOUT Process has moved in recent years from an emerging technology to a commercially available method for effective pollution control. Computational fluid dynamics continues to playa significant role in implementing this technology. -9-