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Title	Enhanced NOx Reduction in Staged Combustion: Technical Application of Premix Technology in Boilers
Creator	Haumann, J.; Knopfli, A.; Sattelmayer, T.
Publisher	Digitized by J. Willard Marriott Library, University of Utah
Date	1994
Spatial Coverage	presented at Maui, Hawaii
Abstract	This paper describes a new approach to the reduct ion of the NOx emissions of oil-fired furnaces (oil no.2 and no.6). The potential of air-staged combust ion was investigated in an experimental and theoretical research program showing a clear advantage for strong air preheat and the use of a premix burner in the first fuel-rich stage instead of a conventional diffusion burner. Using a premix burner (100kWth), the optimum emissions were less than 60% of those from the best diffusion flame in the presence of fuel bound nitrogen. Optimum residence times under substoichiometric conditions were found to be only 100-l50ms. Based on the positive results, this novel technique was developed on an industrial scale using a 2-stage-process for medium size boilers, while large scale power plant boilers will require a 3-stage combustion system. In a cooperative project between a power utility and ABB, a pilot plant of 10MWth was built and intensively tested. The influence of air preheat , oil quality, load variations, primary and secondary equivalence ratios were investigated in a parametric study. Optimum emissions of 27-47ppm (3% 02) for oil no.2 and 04-119ppm NOx for oil no.6 were measured in a load range of 3-10.5MWth while CO and UHC emissions were negligible. A residual 02 content of 0.5-1 % in the stack could be established while maintaining low levels of soot emissions. Based on these results, the potential of the large scale 3-stage process could be estimated to be <=75ppm NOx for a heavy fuel oil with 0.5%N.
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/s63n25zc
Setname	uu_afrc
ID	7802
Reference URL	https://collections.lib.utah.edu/ark:/87278/s63n25zc

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Title	Page 16
Format	application/pdf
OCR Text	Show 16 increase in the NOx emissions for worse oil qualities could be detected for very high N- concentrations, whereby the load dependence reflects only the influence of the primary air temperature. 100 -(") 80 < -zE o particulates en -E 60 _ .. - m CII) c: 0 40 CII) CII) E w 20 _--=.-:::-=:IIr.-;-::_~_::-:_:-::. _ _ _ _ _ _ _ _ _ 0 0 10 20 30 40 50 60 70 80 90 100 9MW Nominallast Last [%] Fig.13: Influence of load on CO- and particulate emissions The particulate emissions increased by a factor of 3 with the higher asphaltene - content (9 times) and the larger Conradson - no. (3 times) of the worst oil quality, while the emissions of CO and unburnt hydrocarbons remained unchanged at a low level. The widespread application of additives was not tested. 250 N 0 200 0~ (") E 150 (5 c E 100 Q. ~ )( 0 Z 50 0 0 0 .1 0 .2 opt. primary air excess ratio res. 02 = 1% recirculation rate 35% 0 .3 0 .4 0 .5 0 .6 --35% - .... -67% --•••• 100% 0 .7 0.8 fuel bound nitrogen content (%) 0 .9 Fig. 14: Influence of the oil quality (fuel - bound N) I (without air preheater)
Setname	uu_afrc
ID	7799
Reference URL	https://collections.lib.utah.edu/ark:/87278/s63n25zc/7799