Susanne K. Langer:

Lyon, Arabella

doi:10.2307/j.ctt5hjt73.18

Cited by 10 publications

(11 citation statements)

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“…Selective noncatalytic reduction, SNCR, is a well-known technique to reduce NO x emissions in combustion processes. Since 1975, when Lyon patented the process called Thermal DeNO x in which ammonia is used as a reducing agent of NO under lean conditions, many works have dealt with the study of such technique in both laboratory, pilot, and full scale plants. − The different combustion devices that exist (utility boilers, waste incinerators, and other stationary combustors), the various nitrogen reducing agents that are used (ammonia, urea, cyanuric acid, etc. ), as well as the possible modifications that can be necessary when implementing the SNCR technique result in a variety of cases and operating conditions which need individual and careful analysis.…”

Section: Introductionmentioning

confidence: 99%

Interactions between Nitric Oxide and Urea under Flow Reactor Conditions

et al. 1998

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An experimental and theoretical study of the interactions between urea and NO under lean selective noncatalytic reduction conditions has been performed. The experiments were conducted in an isothermal quartz flow reactor at atmospheric pressure in the temperature range 700-1500 K. The influence of the temperature, oxygen concentration, and urea/NO ratio on the NO reduction has been analyzed. A reaction mechanism including literature NH 3 , HNCO, and moist CO oxidation subsets as well as their interactions with NO and reactions describing urea thermal decomposition have been used for calculations. The results show that urea is effective in reducing NO in a given temperature window, accompanied by the formation of an appreciable amount of N 2 O, which reaches its maximum value for the higher NO reduction. The impact of oxygen concentration in the 1-10% range is appreciable, and lower O 2 concentrations shift the reduction regime toward higher temperatures, the higher N 2 O formation being observed for the richer environment. Using urea, the onset of NO reduction is shifted to higher temperatures compared to the use of ammonia, even though the effective temperature window for NO reduction roughly coincides for both selective reduction agents. The efficiency of NO reduction and the NO to N 2 O conversion increase as the urea/NO ratio increases, even though at high temperatures the excess of urea can be oxidized to NO. Model predictions are in good agreement with the experimental results and indicate that the classical reaction pathway for urea decomposition (i.e., H 2 N-CO-NH 2 f NH 3 + HNCO) is not able alone to reproduce the experimental findings obtained in the upper temperature range. This is attributed either to uncertainties of the HNCO oxidation mechanism or to the fact that other decomposition channels are likely to be produced. Results of this work as well as other literature data suggest that the method chosen for urea injection is important with respect to the N 2 O emissions attained. Adding urea at least partially decomposed prior to its interaction with NO results in similar NO reduction efficiencies but in considerably lower N 2 O concentrations.

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Section: Introductionmentioning

confidence: 99%

Interactions between Nitric Oxide and Urea under Flow Reactor Conditions

et al. 1998

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“…Over the years significant efforts have been undertaken to develop a detailed reaction mechanism for the selective noncatalytic reduction of nitric oxide by ammonia. − This process, which was discovered by Lyon in 1972 and coined thermal De−NO x , is widely used as a practical NO x control technique, but details of the reaction mechanism remain controversial.…”

Section: Introductionmentioning

confidence: 99%

Branching Fraction of the NH₂ + NO Reaction between 1210 and 1370 K

et al. 1997

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The branching fraction for the NH2 + NO reaction has been determined in the temperature range 1210−1370 K from flow reactor experiments on the NH3/NO/O2 and CO/NH3/NO/O2 systems. The branching fraction is defined as α = k 1/(k 1 + k 2), where NH2 + NO → NNH + OH (1) and NH2 + NO → N2 + H2O (2). The experiments were performed at very low oxygen concentrations to minimize the impact of secondary reactions. The results show that α increases gradually from a value of 0.35 ± 0.04 at 1211 K to 0.45 ± 0.02 at 1369 K. The data blend smoothly with the most recent direct measurements and confirm the significant rise in branching fraction suggested by previous high-temperature determinations in static reactors and flames.

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“…The reaction of NH 2 with NO 2 has been considered to be one of the most important steps in the removal of NO 2 by NH 3 − and in the decomposition of ammonium nitrate (AN) and ammonium dinitramide (ADN) − because of its high probability of producing atomic and radical chain carriers. The possible major product channels are − …”

Section: Introductionmentioning

confidence: 99%

A Mass Spectrometric Study of the NH₂ + NO₂ Reaction

Park

Lin

1997

J. Phys. Chem. A

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The total rate constant and product branching ratios of the NH2 + NO2 reaction have been determined in the temperature range of 300−910 K using a pulsed laser photolysis/mass spectrometric technique by probing H2O and N2O product formation and NO2 reactant decay. A weighted least-squares fit of our result for the total rate constant yields the following expression: k 1 = (8.1 ± 0.33) × 1016 T -1.44 exp(−135/T) cm3/(mol·s). The product branching ratio for the N2O + H2O channel of the NH2 + NO2 reaction obtained by modeling the absolute N2O product yield near or at its plateau value gives 0.19 ± 0.02 without significant temperature dependence, confirming our earlier result obtained by using a high-gain amplifier with no time-resolved information (ref ).

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Susanne K. Langer:

Cited by 10 publications

References 0 publications

Interactions between Nitric Oxide and Urea under Flow Reactor Conditions

Interactions between Nitric Oxide and Urea under Flow Reactor Conditions

Branching Fraction of the NH₂ + NO Reaction between 1210 and 1370 K

A Mass Spectrometric Study of the NH₂ + NO₂ Reaction

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Susanne K. Langer:

Cited by 10 publications

References 0 publications

Interactions between Nitric Oxide and Urea under Flow Reactor Conditions

Interactions between Nitric Oxide and Urea under Flow Reactor Conditions

Branching Fraction of the NH2 + NO Reaction between 1210 and 1370 K

A Mass Spectrometric Study of the NH2 + NO2 Reaction

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Branching Fraction of the NH₂ + NO Reaction between 1210 and 1370 K

A Mass Spectrometric Study of the NH₂ + NO₂ Reaction