Numerical Simulation of SNCR Technology with Simplified Chemical Kinetics Model

Abstract

Abstract. The paper deals with numerical simulation of SNCR method. For numerical modelling was used CFD code Ansys/CFX. SNCR method was described by dominant chemical reaction, which were look up NIST Chemical database. The reactions including reduction of NOx and concentration change of pollutants, like N2O and CO in flue gas too. Proposed chemical kinetics and CFD model was applied to two boilers. Both simulations were compared with experimental measurements. First simulation was used to validation of chemical mechanism. Second simulation was based on first simulation and it was used to verification of compiled SNCR chemical mechanism. Next the new variant of the reagent penetration lance was proposed and compared with the original variants.

Numerical simulation of SNCR (selective non-catalytic reduction) process in coal fired grate boiler

“…Most of the numerical studies consider biomass or waste fired stokers [2e5], grate-kiln plants [6] or pilot scale experiments [7e10]. Papers reporting CFD validation studies of SNCR chemical kinetic model based on pulverised coal boilers have also been published [11,12]. All of the above mentioned literature is dedicated to either optimization of the SNCR process applied to a specific facility utilizing CFD simulations or validation of the numerical model with the experimental data.…”

Convective recirculation effect on the selective non-catalytic reduction behavior in an industrial furnace

“…The fundamental principle of NOx reduction, which occurs in SNCR, is defined by the following chemical reaction (Blejchař and Dolníčková, 2013):…”

“…Several studies have firmly established that, among various operating conditions, the temperature is the leading one to determine the output of the SNCR process (Liang et al, 2014). Nevertheless, besides the temperature range, the NOx reduction depends also on the concentration of O 2 in the flue gas, the composition of additive (e.g., hydrogen, hydrogen peroxide) and the NH 3 /NO molar ratio (Blejchař and Dolníčková, 2013).…”

“…Mixing, however, is damaged by the high viscosity of flue gas and also by problems in finding available injection points. Thus, CFD modelling is crucial to preview the behaviour of the process (Blejchař and Dolníčková, 2013;Han et al, 2003;Tayyeb Javed et al, 2007).…”

Experimental investigation of N2O formation in selective non-catalytic NOx reduction processes performed in stoker boiler

“…The mechanism of formation of N 2 O as a by-product of urea utilisation in SNCR systems has been comprehensively discussed in 19, 20 . Urea (in form of aqueous solution) produces amine radicals in a gradual manner.…”