No Reduction by Selective Noncatalytic Reduction Using Ammonia-Effects of Additives

Abstract

An experimental study of nitric oxide removal by selective noncatalytic reduction (SNCR) using ammonia as reducing agent has been performed in a semi-industrial reactor over the temperature range 973-1200 K. Several chemical compounds, such as CH4, C2H4, C2H6, CH3OH, C2H5OH, and CO, which are usually used in the literature as additives for the SNCR process, have been evaluated. As a result, very high efficiencies (up to 82%) have been achieved in our optimal experimental conditions with the classical SNCR process. The additives seem to make the NO reduction process more effective at lower temperatures. These additives induce a downward shift (up to more than 100 K) of the optimal temperature window for the reduction process, and a slight decrease of the maximum NO reduction level depending on the species and on the additive concentration. The additive utilization effectively decreases residual NH3 emissions.

Experimental and Kinetic Study of the Effect of Additives on the Ammonia Based SNCR Process in Low Temperature Conditions

“…For that reason, the goal of this work, which completes our recent studies on reburning and SNCR processes, is to contribute to a better understanding of the kinetic effect of different additive families on the NO x reduction mechanisms of the ammonia-based SNCR process. The influence of CH 4 , C 2 H 6 , C 2 H 4 , C 2 H 2 , CH 3 OH, C 2 H 5 OH, and CO used as additives has been evaluated.…”

“…For NH 3 , the NSR is fixed to the value of 5.0, which is the optimum point in the present experimental conditions. 34 For the additives, the NSR was varied from 0 to 3.…”

“…The experiments have been performed in a plug-flow reactor, shown in Figure and described elsewhere. , It consists in a 1.1 m long tube with an inner diameter of 8 cm, which is equipped with 13 accesses allowing temperature measurements and gas sampling. Average residence times up to 7 s are obtained depending on the access chosen.…”

“…The NSR is defined as the [RA]/[NO] 0 ratio, where [RA] and [NO] 0 correspond respectively to the concentrations of RA and NO in the flue gas at the location of the injection device. For NH 3 , the NSR is fixed to the value of 5.0, which is the optimum point in the present experimental conditions . For the additives, the NSR was varied from 0 to 3.…”

Experimental Study of the Enhancement of the Selective Noncatalytic Reduction Denitrification Process with Methane and Propane in a Circulating Fluidized Bed

“…Among these additives, gaseous additives showed a remarkable performance in promoting NO conversion efficiency, decreasing the reaction temperature window and controlling the secondary pollutant emission. CH 4 , CO, and H 2 were commonly used gaseous additives for SNCR. − Nimmo et al studied the influences of addition of CH 4 and C 3 H 8 on NOx removal. They concluded that CH 4 and C 3 H 8 could reduce the temperature range of SNCR by 200 and 60 °C, respectively, while maintaining the same NO conversion efficiency.…”