Journal of Chemical Engineering of Japan, vol 29 no 4 pp 620-626(1996)  [Japanese]

KINETICS OF NOx REDUCTION BY UREA SOLUTION IN A PILOT SCALE REACTOR

JUNG BIN LEE AND SANG DONE KIM

Department of Chemical Engineering and Energy & Environment Research Center, Korea Advanced Institute of Science and Technology, TaeJon, 305-701, Korea

Key Words: NOx Reduction, Urea Solution, Kinetics, Additives

The effects of urea molar ratio (1.0 - 2.0), reaction temperature and additives on NO reduction in flue gas have been determined in a pilot-scale flow reactor. A kinetic model is proposed for NO reduction rate with -NH and -CN in selective reducing agents (urea, cyanuric acid, ammonia). Two primary reactions can be expressed kinetically in the DeNOx process as:
N.S. (nitrogenous species)+0x (oxidants)?NO +???(kf; rate constant for NO formation)
N.S.+NO?N2+???(kr; rate constant for NO reduction)
in which the rate constants of kf and kr in the model are determined from the experimental data in the temperature range 1173 K - 1373 K as:
kf=4.0l×10^11 exp (-267/RT)
kr=7.24×10^10 exp (-230/RT)
The proposed model can predict the lowered activation energies caused by the addition of different species and molar ratio to NO.