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The indicated strong PA-driven IRZ and SA-driven ERZ would produce very well attached flame with a relatively short PA core flow down the burner axis. This would result in shortened flame length and increased PA and coal dust mixing within the flame base, which would lead to lower UBC values.
Also, the separate internal and external recirculation zone structure completely isolates the primary ignition zone from oxygen in the SA/TA flow to further reduce NOX production. In contrast, the streamlines for the original burner configuration lack the PA-driven IRZ, which can result in a longer tubular flame with high UBC values due to insufficient mixing of coal with the combustion air.
The retrofit of this FW PF/SF type burner is limited to the installation of VS III low NOX coal burner components (colored in red) including the venturi coal nozzle with integrated FSR and low swirl coal spreader (US Patent #6,474,250), SA and TA diverters, and fixed SA swirl vanes.
The desired recirculation zones for good flame attachment and low NOX
The operators of coal-fired power plants today are interested in improvements that can be made to prevent the adverse impact on boiler performance, combustion efficiency and CO emissions associated with existing low NOX burners, without the high cost and long outage duration of traditional full burner replacement. RPI has demonstrated components-only burner solutions to address these problems on several low NOX burner designs. In all cases, CFD modeling was used to assist in the burner design and proved valuable. The same approach has now been applied to several other low NOX burner designs, demonstrating similar results to those observed in new burner installation. In the competitive atmosphere of today’s energy market, it is important for utility companies to seek proven, cost effective and technology-based solutions for achieving environmental compliance goals.
Editor’s note: This paper, PWR2011-55270, was printed with permission from ASME and was edited from its original format. To purchase this paper in its original format or find more information, visit the ASME Digital Store at www.asme.org
Stephen W. Black is an engineer in the Fuel Equipment Design Department of Riley Power’s headquarters in Worcester, Mass. His work focuses primarily on the design, development and application of fuel burning equipment for coal, oil and gas fired steam generators. His experience includes burner equipment design for wall-fired, T-fired and Riley’s TURBO furnaces. Black graduated from Worcester Polytechnic Institute with a bachelors and masters degree in mechanical engineering.
Murat Yaldizli is an engineer in the Fuel Equipment Design Department of Riley Power’s headquarters in Worcester, Mass. His work focuses primarily on CFD modeling and analysis of contract and development projects. Equipment to be analyzed primarily includes low NOX burners, windboxes and furnaces for wall-fired, T-fired and turbo-fired boilers, SCR and SO2 scrubber systems and components. Yaldizli graduated from Michigan State University with a Ph.D. degree in mechanical engineering.
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