A comparative kinetic study of SNCR process using ammonia

Javed, M. Tayyeb; Ahmed, Zaki; Ibrahim, Muhammad Asim; Irfan, Naseem

doi:10.1590/s0104-66322008000100012

Cited by 14 publications

(2 citation statements)

References 14 publications

(17 reference statements)

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“…Additionally, the NO in the flue increased with decreasing initial NH 3 concentration. This is very interesting and may be attributed to NO reduction by NH 3 at higher initial NH 3 concentrations via selective catalytic reduction (SCR) [14] [15] [16] where the stainless-steel thermocouple bundle may serve as a catalyst, or by selective non-catalytic reduction mechanisms [17] [18] [19].…”

Section: Nh 3 Oxidationmentioning

confidence: 99%

An Experimental Observation of the Thermal Effects and NO Emissions during Dissociation and Oxidation of Ammonia in the Presence of a Bundle of Thermocouples in a Vertical Flow Reactor

Holden¹,

Zhang²,

Gao³

et al. 2023

ACES

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Ammonia (NH 3 ) dissociation and oxidation in a cylindrical quartz reactor has been experimentally studied for various inlet NH 3 concentrations (5%, 10%, and 15%) and reactor temperatures between 700 K and 1000 K. The thermal effects during both NH 3 dissociation (endothermic) and oxidation (exothermic) were observed using a bundle of thermocouples positioned along the central axis of the quartz reactor, while the corresponding NH 3 conversions and nitrogen oxides emissions were determined by analysing the gas composition of the reactor exit stream. A stronger endothermic effect, as indicated by a greater temperature drop during NH 3 dissociation, was observed as the NH 3 feed concentration and reactor temperature increased. During NH 3 oxidation, a predominantly greater exothermic effect with increasing NH 3 feed concentration and reactor temperature was also evident; however, it was apparent that NH 3 dissociation occurred near the reactor inlet, preceding the downstream NH 3 and H 2 oxidation. For both NH 3 dissociation and oxidation, NH 3 conversion increased with increasing temperature and decreasing initial NH 3 concentration. Significant levels of NO X emissions were observed during NH 3 oxidation, which increased with increasing temperature. From the experimental results, it is speculated that the stainless-steel in the thermocouple bundle may have catalysed NH 3 dissociation and thus changed the reaction chemistry during NH 3 oxidation.

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Section: Nh 3 Oxidationmentioning

confidence: 99%

An Experimental Observation of the Thermal Effects and NO Emissions during Dissociation and Oxidation of Ammonia in the Presence of a Bundle of Thermocouples in a Vertical Flow Reactor

Holden¹,

Zhang²,

Gao³

et al. 2023

ACES

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“…Thermal de-NO, also called selective non-catalytic reduction of NO by ammonia (SNCR), is a common NO reduction technique which is efficient in a small temperature range centered around 1200-1250 K. Many experimental and kinetic modeling studies concern SNCR (Dagaut and Nicolle 2005a;Javed et al 2008;Miller and Bowman 1989;Miller and Glarborg 1999;Schmidt and Bowman 2001). However, existing kinetic models show weaknesses and sometimes fail to represent the kinetics of ammonia oxidation (Kobayashi et al 2019) whereas interest for this fuel or energy carrier is growing.…”

Section: Introductionmentioning

confidence: 99%

On the Oxidation of Ammonia and Mutual Sensitization of the Oxidation of No and Ammonia: Experimental and Kinetic Modeling

Dagaut

2019

Combustion Science and Technology

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The selective non-catalytic reduction of NO by ammonia (SNCR) has been extensively studied but no activation of ammonia oxidation by nitric oxide had been reported. Experiments performed in a jetstirred reactor (JSR) at atmospheric pressure for various equivalence ratios (0.1-2) and initial concentrations of NH 3 (500 to 1000 ppm) and NO (0 to 1000 ppm) revealed kinetic interactions similar to the so-called mutual sensitization of the oxidation of hydrocarbons and NO. The experiments were performed at fixed residence times of 100 and 200 ms, and variable temperature ranging from 1100 to 1450 K. Kinetic reaction mechanisms were used to simulate these experiments and ammonia oxidation. The most reliable model from the literature was updated (NH 2 +H → NH+H 2 , HNO+H → NO+H 2 ) to better predict ammonia-air burning velocities. It showed the mutual sensitization of the oxidation of ammonia and nitric oxide proceeds through several reaction pathways leading to OH production which is mainly responsible for ammonia oxidation in the current conditions: NH 2 + NO → NNH + OH, NNH

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Combustion Kinetic Modeling

Javed

Irfan

Ibrahim

2010

Handbook of Combustion

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Combustion is a complex phenomenon characterized by the interaction and competition of various physical and chemical processes. The correct description of chemical changes requires the application of reaction mechanisms that consist of several hundreds or thousands of elementary reactions. This creates an opportunity for kinetic modeling to play important role in understanding the combustion phenomenon. This chapter provides an overview of combustion modeling, the main aim being to present a comprehensive knowledge base for combustion kinetic modeling. The coupling of fluid dynamics and chemical kinetics using commercial software such as CHEMKIN and FLUENT is also discussed. Moreover, an exemplary approach for reducing complex chemical reaction mechanisms is illustrated with reference to an H 2 + O 2 mixture in an adiabatic system. This approach involves the identification of redundant species via rate sensitivity analysis, and of redundant reactions, by principal component analysis of the rate sensitivity matrix. An eigenvalue–eigenvector analysis is used to extract meaningful kinetic information from linear sensitivity coefficients computed for all species of chemical mechanism at several time points. The main advantage of this method lies in its ability to reveal those parts of the mechanism, which consist of strongly interacting reactions, and to indicate their importance within the mechanism. By using the above procedures, reduced reaction mechanisms could be developed at different chosen conditions and employed in CFD codes in place of detailed mechanisms, giving due consideration to flow fields.

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A comparative kinetic study of SNCR process using ammonia

Cited by 14 publications

References 14 publications

An Experimental Observation of the Thermal Effects and NO Emissions during Dissociation and Oxidation of Ammonia in the Presence of a Bundle of Thermocouples in a Vertical Flow Reactor

An Experimental Observation of the Thermal Effects and NO Emissions during Dissociation and Oxidation of Ammonia in the Presence of a Bundle of Thermocouples in a Vertical Flow Reactor

On the Oxidation of Ammonia and Mutual Sensitization of the Oxidation of No and Ammonia: Experimental and Kinetic Modeling

Combustion Kinetic Modeling

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