CFD Modeling and Field Testing of a 600-MW Wall-Fired Boiler Burning Low-Volatile Bituminous Coal

Abstract

CFD modeling and field testing results of a 600-MW wall-fired super-critical unit burning low-volatile bituminous coal are presented in this paper. The primary goal of the low-NO _x combustion improvement was to reduce NO _x emissions from the baseline value 650–680 mg/N m³ to 450 mg/N m³. During the design process, Harbin Boiler Company (HBCo) made some improvements on the initial burner design to further improve burner flame structure and reduce NO _x formation based on the findings from CFD modeling conducted by SmartBurn, LLC (SmartBurn). Field testing results indicated that the strongest inner secondary air swirl, modest outer secondary air swirl, finer coal particles, lower excess O₂, and higher OFA to total boiler air ratio are critical to achieve lower NO _x emissions. However, lower excess O₂ and higher OFA ratio resulted in higher unburned carbon in fly ash, which means lower boiler efficiency. Therefore, balancing acceptable NO _x emissions and higher boiler efficiency needs to be considered during the combustion optimization. NO _x emissions of 419 mg/N m³ were achieved during the final testing with acceptable boiler efficiency, which exceeded the goal of 450 mg/N m³.