Detailed Kinetic Modeling of Moist CO Oxidation Inhibited by Trace Quantities of HCl

Roesler, J. F.; Yetter, Richard A.; Dryer, Frederick L.

doi:10.1080/00102209208947157

Cited by 46 publications

(40 citation statements)

References 7 publications

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“…At higher injection temperatures, CO returns to equilibrium levels expected for methane/air combustion products without CH 2 Cl 2 injection. This is consistent with a two-stage CHC combustion process of fast CHC reactions to form CO and intermediate species, followed by a slower, chlorine-inhibited CO to CO 2 burnout [13,[37][38][39][40].…”

Section: Major Speciessupporting

confidence: 58%

Postflame reaction chemistry of dichloromethane: variations in equivalence ratio and temperature

Sgro

Koshland

Lucas

et al. 2000

Combustion and Flame

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We report on the destruction pathways and byproduct formation of dichloromethane (CH 2 Cl 2 ) in conditions typical of incinerator postflame regions (injection temperature ϭ 900 -1200 K; equivalence ratio ϭ 0.6, 0.9, 1.0, 1.1; residence time ϭ 0.28 -0.35 s). This is the first study to independently vary equivalence ratio and temperature, and evaluate their impacts on byproduct yield and destruction efficiency. We inject 750 ppm CH 2 Cl 2 into postflame combustion products and measure byproducts with extractive FTIR spectroscopy. We use a detailed chemical kinetic mechanism and reaction rate analysis to predict the changes in reaction pathways as a function of equivalence ratio. The predictions for major products and several intermediate species compare well with experiments; the largest disparities are an underprediction of phosgene (CCl 2 O) and an overprediction of methyl chloride (CH 3 Cl). Both the experiment and the numerical predictions show increased destruction at lower equivalence ratios. However, the experiments reveal increased levels of stable chlorinated organics at lower equivalence ratios, opposite to the numerical prediction. We discuss reasons for this discrepancy and implications of these results for designing control strategies to promote full conversion to HCl and to reduce chlorinated byproduct emissions.

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Section: Major Speciessupporting

confidence: 58%

Postflame reaction chemistry of dichloromethane: variations in equivalence ratio and temperature

Sgro

Koshland

Lucas

et al. 2000

Combustion and Flame

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“…During combustion or gasification, the chlorine is released as HCl and Cl 2 , which are known to act as inhibitor by catalyzing the recombination of radicals O, H, OH, and HO 2 in the flame. Therefore, HCl is likely to affect the oxidation of CO [2][3][4][5] and the formation of NO [6,7] in combustion.…”

Section: Introductionmentioning

confidence: 99%

Influence of HCl on CO and NO emissions in combustion

Wei¹,

Wang²,

Dian-fu³

et al. 2009

Fuel

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a b s t r a c tThe influence of HCl on CO and NO emissions was experimentally investigated in an entrained flow reactor (EFR) and an internally circulating fluidized bed (ICFB). The results in EFR show the addition of HCl inhibits CO oxidation and NO formation at 1073 K and 1123 K. At the lower temperature (1073 K) the inhibition of HCl becomes more obvious. In ICFB, chlorine-containing plastic (PVC) was added to increase the concentration of HCl during the combustion of coal or coke. Results show that HCl is likely to enhance the reduction of NO and N 2 O. HCl greatly increases CO and CH 4 emission in the flue gas. A detailed mechanism of CO/NO/HCl/SO 2 system was used to model the effect of HCl in combustion. The results indicate that HCl not only promotes the recombination of radicals O, H, and OH, but also accelerates the chemical equilibration of radicals. The influence of HCl on the radicals mainly occurs at 800-1200 K.

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“…ChemKin 4 was used as a modeling platform along with a core kinetic mechanism developed by Niksa, Helble, and coworkers [7] with the chlorine chemistry of Roessler et al [8,9] to predict the concentrations of Cl 2 present in the flue gas as it enters the impingers, using the timetemperature history in the furnace as previously reported. In Roessler's model, the Cl 2 is formed from the recombination of chlorine radicals within the reactor.…”

Section: Homogeneous Oxidation -University Of Utah Resultsmentioning

confidence: 99%

Fundamentals of Mercury Oxidation in Flue Gas

Lighty¹,

Silcox²,

Senior³

et al. 2008

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The objective of this project was to understand the importance of and the contribution of gasphase and solid-phase coal constituents in the mercury oxidation reactions. The project involved both experimental and modeling efforts. The team was comprised of the University of Utah, Reaction Engineering International, and the University of Connecticut. The objective was to determine the experimental parameters of importance in the homogeneous and heterogeneous oxidation reactions; validate models; and, improve existing models. Parameters studied include HCl, NOx, and SO 2 concentrations, ash constituents, and temperature.The results suggested that homogeneous mercury oxidation is below 10% which is not consistent with previous data of others and work which was completed early in this research program. Previous data showed oxidation above 10% and up to 100%. However, the previous data are suspect due to apparent oxidation occurring within the sampling system where hypochlorite ion forms in the KCl impinger, which in turn oxidized mercury. Initial tests with entrained iron oxide particles injected into a flame reactor suggest that iron present on fly ash particle surfaces can promote heterogeneous oxidation of mercury in the presence of HCl under entrained flow conditions.Using the data generated above, with homogeneous reactions accounting for less than 10% of the oxidation, comparisons were made to pilot-and full-scale data. The results suggest that heterogeneous reactions, as with the case of iron oxide, and adsorption on solid carbon must be taking place in the full-scale system.Modeling of mercury oxidation using parameters from the literature was conducted to further study the contribution of homogeneous pathways to Hg oxidation in coal combustion systems. Calculations from the literature used rate parameters developed in different studies, in some cases using transition state theory with a range of approaches and basis sets, and in other cases using empirical approaches. To address this, rate constants for the entire 8-step homogeneous Hg oxidation sequence were developed using an internally consistent transition state approach. These rate constants when combined with the appropriate sub-mechanisms produced lower estimates of the overall extent of homogeneous oxidation, further suggesting that heterogeneous pathways play an important role in Hg oxidation in coal-fired systems.3

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Detailed Kinetic Modeling of Moist CO Oxidation Inhibited by Trace Quantities of HCl

Cited by 46 publications

References 7 publications

Postflame reaction chemistry of dichloromethane: variations in equivalence ratio and temperature

Postflame reaction chemistry of dichloromethane: variations in equivalence ratio and temperature

Influence of HCl on CO and NO emissions in combustion

Fundamentals of Mercury Oxidation in Flue Gas

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