An integrated approach for combustor design to minimize nitrogen oxide emissions using CFD methods

The objective of the present investigation is to apply a novel concept of integrated design to combustor modeling using computational fluid dynamics (CFD) methods. Most of the existing studies to date were done separately for various combustion modifications like air staging or reburning. The current approach looks at integrating all these methods and optimizing the system. Consequently, it offers an alternative for a large variety of applications in which furnace optimization plays a key role in efficient operation and NOx emissions control. The objectives of this work were to understand the influence of mixing and chemistry during reburning and to balance their effect in order to maximize NOx reduction.;A CFD based integrative approach for combustor design is presented and applied to a pilot-scale 147 kW Down-fired Combustor (DFC) unit for maximum NOx reduction. The approach is based on the integration of several NOx control methods, including burner optimization, air staging and reburning Different scenarios are discussed and recommendations are made for maximum NOx reduction. The investigation is divided in separate parts for burner optimization, combustor modeling, and experimental results. The experimental results include initial data for the "tuning" of the numerical model as well as validation results on optimized configurations. The combustor modeling study was carried out in three stages, namely: (1) the baseline test case, (2) the mixing optimization stage, and (3) the reburning test case. In the baseline test case, the numerical model was tuned to the experimental data. In the mixing optimization stage, the impact of mixing on the reburning process was investigated using CFD models and an advanced mixing model. Finally, in the reburning test case, the results from the previous stages were integrated and applied to the reburning process. Optimum parameters obtained from each stage were used in subsequent simulations and NOx reduction was targeted at every stage.;In conclusion, this study showed that the integrated approach can be used effectively for a reburn case application, achieving significant NO x reduction. The effect of integration was demonstrated both theoretically and experimentally as applied to a pilot-scale Down-fired combustor.