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Title	Effects of Mixing and Thermal Quenching on NO Reduction by Selective Non-Catalytic Reduction in the Presence of CO
Creator	Brouwer, J.; Eddings, E. G.; Heap, M. P.; Pershing, David W.; Smith, Philip J.
Publisher	Digitized by J. Willard Marriott Library, University of Utah
Date	1995
Spatial Coverage	presented at Monterey, California
Abstract	The effects of thermal environment (injection temperature and quench rate), reactant ratios (initial NO and NH3/NO) and reagent mixing on the selective non-catalytic reduction (SNCR) of NO by ammonia have been investigated in a pilot scale facility in the presence and absence of CO. A reduced chemical kinetic mechanism for the prediction of SNCR chemistry has been developed and incorporated into a two-dimensional, CFD-based turbulent reacting flow model for the prediction and investigation of thermal and mixing effects on the reduction process in the presence of CO. The experiments and modeling show that with rapid mixing and near isothermal conditions, very low NO emissions are achievable (around 50 ppm) independent of inlet NO levels (ranging from 250 to 500 ppm). Chemical kinetic modeling is in agreement with this finding but overpredicts the reduction efficiencies achieved in the experiment since it ignores the effects of turbulence, mixing and heat transfer. With less rapid mixing and a thermally quenched zone, NO reduction efficiencies were much lower than those predicted by homogeneous chemical kinetics. However, predictions of SNCR performance made by the fully coupled turbulent reacting flow and reduced SNCR chemical kinetic mechanism model quantitatively predict trends and magnitudes of NO reduction. The presence of CO was found experimentally and computationally to shift and narrow the temperature window for effective reduction of NO; hence, CO was found to both increase and decrease NO reduction efficiencies depending on injection temperature and quench rate.
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Format	application/pdf
Language	eng
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Scanning Technician	Cliodhna Davis
ARK	ark:/87278/s6cn76gw
Setname	uu_afrc
ID	9263
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6cn76gw

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Title	Page 9
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OCR Text	Show as has long been indicated by homogeneous SNCR chemistry. Reduction efficiencies that are independent of initial NO levels indicate that costly combustion modifications for NO reduction may be unnecessary if an SNCR zone is incorporated into furnace design. The presence of CO was found to be beneficial at low injection temperatures and high quench-rates and detrimental at high injection temperatures and low quench rates. Increases in the momentum of the reagent! diluent/CO jet was found to increase NO reduction in the presence of CO and reduce NO reduction in the absence of CO due to increases in chemical rates when CO is present. A reduced chemical kinetic mechanism for SNCR chemistry has been developed and incorporated .. into a turbulent reacting flow model. Detailed modeling of the complex interactions of turbulent mixing, dispersion, and chemical reaction that occur in the SNCR process was found to capture these trends and quantitatively predict NO reduction efficiencies. Acknowledgments Financial support for this program was provided by the US EPA under Contract No. 68D20 121. The authors would like to acknowledge the help of Dr. Ade1 Sarofun in the development of the SNCR mixing model and Messrs. Dana Overacker, Dale Inkley, Dave Wagner and Dave Warren for the construction and operation of the test facility. References 1 Lyon, RK., U.S. Patent No. 3,900,554, 1975. 2 Muzio, LJ., Arand, J.K., and Teixeira, D.P., Sixteenth Symposium (International) on Combustion, p.199. The Combustion Institute, 1977. 3 Arand, J.K.: U.S. Patent No. 4,325,924, 1982. 4 Brogan, T. R.: U.S. Patent No. 4,335,084, 1982. 5 Perry, R.A., and Siebers, D.L.: Nature vol. 324, p. 657, 1986. 6 Heap, M.P., Chen, S.L., McCarthy, J.M., and Pershing, D.W. Nature vol. 335. p. 691,1988. 7 Chen, S.L., Lyon, R.K., and Seeker, W.R., AFRC Fa)) International Symposium on NDx Control, Waste Incineratjon and Oxygen Enriched Combustion, Paper #32, San Francisco, CA, 1990. 8 Lyon, RK. and Hardy J.E: Ind Eng Chern Fundam, vol. 25 p.19, 1986. 9 Teixeira, D.P., Muzio, L.J.,and Montgomery, T.A. Paper presented at the AFRCI JERC International Conference on Enyironmental Control of Combustion processes, Honolulu, Hawaii, 1991. 10 Chen, S.L., Ho, L, Maly, P.M., Payne R., and Seeker, W.R. Paper presented at the Joint EPRIIEPA Symposium on Stationary NOx Control, Bal Harbor, Florida, 1993. Page 9
Setname	uu_afrc
ID	9254
Reference URL	https://collections.lib.utah.edu/ark:/87278/s6cn76gw/9254