Kinetics of NOx reduction by urea solution in a pilot scale reactor

Abstract

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)+Ox (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=4.01×1011 exp (-267/RT) kr=7.24×1010 exp (-230/RT) The proposed model can predict the lowered activation energies caused by the addition of different species and molar ratio to NO.