Journal of Environmental Science International (한국환경과학회지)

The Korean Environmental Sciences Society (한국환경과학회)
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Application of Hybrid SNCR/SCR process for Improved N Ox Removals Efficiency of SNCR

SNCR의 N Ox 제거효율 향상을 위한 Hybrid SNCR/SCR 공정 응용

  • Published : 2003.09.01
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Abstract

The objective of this research was to test whether, under controlled laboratory conditions, hybrid SNCR/SCR process improves N $O_{x}$ removal efficiency in comparison with the SNCR only. The hybrid process is a combination of a redesigned existing SNCR with a new downstream SCR. N $O_{x}$ reduction experiments using a hybrid SNCR/SCR process have been conducted in simple NO/N $H_3$/ $O_2$ gas mixtures. Total gas flow rate was kept constant 4 liter/min throughout the SNCR and SCR reactors, where initial N $O_{x}$ concentration was 500 ppm in the presence of 5% or 15% $O_2$. Commercial catalysts, $V_2$ $O_{5}$ -W $O_3$-S $O_4$/Ti $O_2$, were used for SCR N $O_{x}$ reduction. The residence time and space velocity were around 1.67 seconds and 2,400 $h^{-1}$ or 6000 $h^{-1}$ in SNCR and SCR reactors, respectively. N $O_{x}$ reduction of the hybrid system was always higher than could be achieved by SNCR alone at a given value of N $H_{3SLIP}$. Optimization of the hybrid system performance requires maximizing N $O_{x}$ removal in the SNCR process. An analysis based on the hybrid system performance in this lab-scale work indicates that a equipment with N $O_{xi}$ =500 ppm will achieve a total N $O_{x}$ removal of about 90 percent with N $H_{3SLIP}$ $\leq$ 5 ppm only if the SNCR N $O_{x}$ reduction is at least 60 percent. A hybrid SNCR/SCR process has shown about 26∼37% more N $O_{x}$ reduction than a SNCR unit process in which a lower temperature of 85$0^{\circ}C$ turned out to be more effective.be more effective.

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References

  1. Gullett, B. K., P. W. Groff, M. L. Lin and J. M. Chen, 1994, $NO_{x}$, Removal with Combined Selective Catalytic Reduction and Selective Noncatalytic Reduction: Pilot-Scale Test Results, J. Air & Waste Manage. Assoc., 44, 1188-1194
  2. Wendt, J. O. L., P. L. William, W. G. Paul and K. S. Ravi, 2001, Hybrid SNCR-SCR Technologies for $NO_{x}$, Control: Modeling and Experiment, AlChE Journal, 47(11), 2603-2617 https://doi.org/10.1002/aic.690471123
  3. Keshavaraja, A., X. She and M. FlytzaniStephanopoulos, 2000, Selective catalytic reduction of NO with methane over Ag-alumina catalysts, Applied Catalysis B: Environmental, 27, L1-L9 https://doi.org/10.1016/S0926-3373(00)00131-4
  4. Ma, A. Z., M. Muhler and W. Grunert, 2000, Selective catalytic reduction of NO by ammonia over Raney-Ni supported Cu-ZSM-5 II. Interactions between support and supported CuZSM-5, Applied Catalysis B: Environmental, 27, 37-47 https://doi.org/10.1016/S0926-3373(00)00133-8
  5. Monte, R. D, P. Fornasiero, J. Kaspar, P. Rumori, G. Gubitosa and M. Graziani, 2000, Pd/$Ce_{0.6}Zr_{0.4}O_{2}$/$Al_{2}O_{3}$ as advanced materials for three-way catalysts Part 1. Catalyst characterisation, thermal stability and catalytic activity in the reduction of NO by CO, Applied Catalysis B: Environmental, 24, 157-167 https://doi.org/10.1016/S0926-3373(99)00102-2
  6. Takahashi, S., I. Yamashita and K. Korematsu, 1990, Influence of Initial Concentration on De$NO_{x}$ Process by Ammonia Addition, JSME International Journal, Series II, 3(2), 377-383
  7. Miller, J. A. and C. T. Bowman, 1989, Mechanism and Modeling of Nitrogen Chemistry in Combustion, Prog. Energy Combust. Sci., 15, 287 https://doi.org/10.1016/0360-1285(89)90017-8
  8. Long R. Q. and R. T. Yang, 2000, Selective catalytic reduction of NO with ammonia over $V_{2}O_{5}$ doped Ti$O_{2}$ pillared clay catalysts, Applied Catalysis B: Environmental, 24, 13-21 https://doi.org/10.1016/S0926-3373(99)00092-2
  9. Nova, I., L. dall'Acqua, L. Lietti, E. Giamello and P. Forzatti, 2001, Study of thermal deactivation of a de $NO_{x}$ commercial catalyst, Applied Catalysis B: Environmental, 35, 31-42 https://doi.org/10.1016/S0926-3373(01)00229-6
  10. Miller, C. A. and R. K. Srivastava, 2000, The combustion of Orirnulsion and its generation of air pollutants, Prog. Energy Combust. Sci., 26, 131-160 https://doi.org/10.1016/S0360-1285(99)00014-3
  11. Lyon, R. K., A. M. Dean and J. E. Hardy, 1982, Kinetics and mechanism of $NH_{3}$ oxidation, Proceedings of the Combustion Institute, 9, 97
  12. Kasuya, F., P. Glarborg, J. E. Johnsson and K. Dam-Johansen, 1995, The Thermal De$NO_{x}$ process: influence of partial pressures and temperature, Chem. Eng. Sci., 50(9), 1455-1466 https://doi.org/10.1016/0009-2509(95)00008-S
  13. Kasaoka, S., E. Sasaoka, M. Nagahiro and K. Kawakami, 1979, Noncatalytic reduction of nitrogen monoxide with ammonia and oxidation of ammonia with oxygen, Chem. Soc. Japan, 1, 138