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Title	The Radially Stratified Flame Core Burner a Low-NOx Burner of Novel Type
Creator	Beer, J. M.; Toqan, M. A.; Berg, L.; Testa, A.; Teare, J. D.
Publisher	Digitized by J. Willard Marriott Library, University of Utah
Date	1991
Spatial Coverage	presented at Honolulu, Hawaii
Abstract	Results of an investigation to establish the design principles of a 10w-NOx burner of novel design are discussed. The admixing of the combustion air to the fuel is staged by radial stratification in the flame due to the combination of swirling burner air flow and a strong positive radial density gradient. Fuel/air mixing is suppressed close to the burner but is promoted further downstream where vortex breakdown results in the development of a toroidal recirculation zone in the central region of the flame. A flexible experimental burner capable of varying the radial distributions of the combustion air flow and the swirl velocity has been designed and constructed. Computer modeling of the flow, temperature and stable species concentration distributions in natural gas-air turbulent flames guided parametric and detailed experimental studies which were carried out in the 1.2mx1.2mx4.Sm test section of the MIT Combustion Research Facility. Results of experiments showed that by the optimization of the flow in the radially stratified flame core (RSFC) burner, emission levels of 70ppm NOx and 56ppm CO can be obtained with natural gas fuel flames. Further reductions to below 15ppm NOx were obtained when flue gas recirculation and steam injection were added to the aerodynamically optimized natural gas flames.
Type	Text
Format	application/pdf
Language	eng
Rights	This material may be protected by copyright. Permission required for use in any form. For further information please contact the American Flame Research Committee.
Conversion Specifications	Original scanned with Canon EOS-1Ds Mark II, 16.7 megapixel digital camera and saved as 400 ppi uncompressed TIFF, 16 bit depth.
Scanning Technician	Cliodhna Davis
ARK	ark:/87278/s6qj7kvf
Setname	uu_afrc
ID	7270
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6qj7kvf

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Title	Page 10
Format	application/pdf
OCR Text	Show off) normally imposes a limit on the amount of recirculation before economic considerations of increased costs of ducting and pumping energy show diminishing returns. External recirculation of flue gas through the burner is a method frequently used for reducing NOx emission. The usual practice is to introduce the flue gas into the windbox of the burner air supply and mix it with the total amount of the combustion air before entry to the burner. The multiannular design of the RSFC burner permits flue gas to be recirculated through any or all of the burner nozzles. By introducing the flue gas through the primary and secondary air nozzle the effect on the fuel/air interface is accentuated and a smaller amount of recirculated gas is needed to achieve the same extent of NOx reduction. The high flame stability of the RSFC design is also favorable for allowing reduced O2 concentration of the oxidant surrounding the fuel gas jet. The high flame stability is illustrated in Figure 12 by results of previous studies (Chigier et al., 1970) of the blow off velocity variation in pure methane and partially premixed methane/air jets as a function of the rate of rotation of the air around the jet. In these early experiments the air surrounding the jet was set into rotation by a rotatable cylindrical screen and the extent of induced rotation was characterized by the circulation, r, the product of the screen radius and its circumferential velocity. NOZZLe DIANeTe .. • 3-""''''- .0 STAlL! 'LANI. 0-' 0.2 0,' c.. 0" 0" 0" 0-' 0" FUel CONCENTRAnON, F/~ + A) Figure 12. Flame Stability Diagram for Propane/Air Turbulent Diffusion Flame (Chigier et al., 1970) 10
Setname	uu_afrc
ID	7265
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6qj7kvf/7265