Sulfur in the Burnt Gas of Hydrogen-Oxygen Flames

Fenimore, C.P.; Jones, G.W.

doi:10.1021/j100894a057

Cited by 63 publications

(37 citation statements)

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“…This reaction has been assumed to be an important consumption step for SO 3 in flames [18][19][20][21][22] and in flow reactor experiments, 7,10 whereas the reverse step between SO 2 and O 2 (2b) has been believed to contribute to SO 3 formation in SO 2 /O 2 systems. 6, 23 The present analysis indicate that reaction 2 is too slow to be important in any of these systems and that the observed SO 3 consumption must be attributed to other reactions, primarily SO 3 + H (1).…”

Section: Modeling Results and Discussionmentioning

confidence: 99%

“…10,16,17 The rate constant for the reaction between SO 3 and O (2) has not been measured directly and reported data vary by several orders of magnitude. Indirect determinations have been reported on the basis of results from laminar premixed flames [18][19][20][21][22] and, for the reverse step, from reactor experiments. 10,23 A recent re-interpretation of selected flame results, 12 based on a more accurate value of k 4 , indicates a fairly high rate constant for reaction SO 3 + O h SO 2 + O 2 , in agreement with earlier evaluations, [20][21][22] and a fast reaction is also supported by other experiments.…”

Section: Introductionmentioning

confidence: 99%

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Reactions of SO₃ with the O/H Radical Pool under Combustion Conditions

Hindiyarti

Glarborg²,

Marshall

2007

J. Phys. Chem. A

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The reactions of SO 3 with H, O, and OH radicals have been investigated by ab initio calculations. For the SO 3 + H reaction (1), the lowest energy pathway involves initial formation of HSO 3 and rearrangement to HOSO 2 , followed by dissociation to OH + SO 2 . The reaction is fast, with k 1 ) 8.4 × 10 9 T 1.22 exp(-13.9 kJ mol -1 /RT) cm 3 mol -1 s -1 (700-2000 K). The SO 3 + O f SO 2 + O 2 reaction (2) may proceed on both the triplet and singlet surfaces, but due to a high barrier the reaction is predicted to be slow. The rate constant can be described as k 2 ) 2.8 × 10 4 T 2.57 exp(-122.3 kJ mol -1 /RT) cm 3 mol -1 s -1 for T > 1000 K. The SO 3 + OH reaction to form SO 2 + HO 2 (3) proceeds by direct abstraction but is comparatively slow, with k 3 ) 4.8 × 10 4 T 2.46 exp(-114.1 kJ mol -1 /RT) cm 3 mol -1 s -1 (800-2000 K). The revised rate constants and detailed reaction mechanism are consistent with experimental data from batch reactors, flow reactors, and laminar flames on oxidation of SO 2 to SO 3 . The SO 3 + O reaction is found to be insignificant during most conditions of interest; even in lean flames, SO 3 + H is the major consumption reaction for SO 3 .

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Section: Modeling Results and Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Reactions of SO₃ with the O/H Radical Pool under Combustion Conditions

Hindiyarti

Glarborg²,

Marshall

2007

J. Phys. Chem. A

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“…These results were similar to the conversion trends previously studied at higher gas temperatures and indicate that sufficient levels of SO 3 can be generated even when burning low-sulfur coal. 7,8 …”

Section: Resultsmentioning

confidence: 99%

“…This process has been studied at boiler temperatures and reviewed by Cullis and Mulcahy. [4][5][6][7][8][9][10] The motivating factor for many of these efforts was the desire to minimize corrosion in coal-fired boilers and economizer sections which resulted when the SO 3 reacted with water to form sulfuric acid. The process, while potentially detrimental to boiler tubes, may be beneficial if applied immediately upstream of the electrostatic precipitator.…”

Section: Introductionmentioning

confidence: 99%

An Alternative to Additional SO₃ Injection for Fly Ash Conditioning

Bayless

Khan

Tanneer

et al. 2000

Journal of the Air & Waste Management Association

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Small concentrations, approximately 2-10 parts per million (ppm), of injected sulfur trioxide (SO 3 ) have improved particulate collection efficiencies of electrostatic precipitators burning lower-sulfur coal. However, the addition of extra SO 3 not only incurs costs but also presents negative environmental effects. This work explored a method that could be applied to existing coal-fired power plants to convert the sulfur dioxide (SO 2 ) already present in the flue gas to sufficient levels of SO 3 for fly ash conditioning as an alternative to adding SO 3 by burning elemental sulfur. During this research, a pre-mixed natural gas flame was used to promote the conversion of SO 2 to SO 3 in a drop-tube furnace with average non-flame, free stream gas temperatures of 450 and 1000 K. SO 3 concentrations measured by wet chemistry and confirmed using elemental balances of other sulfur species measured by gas chromatography revealed that as much as 7% of SO 2 was homogeneously transformed to SO 3 . The results also showed that at low temperatures, the rate at which SO 3 is converted back to SO 2 decreased, thus extending the time period during IMPLICATIONS Pulverized-coal-fired power plants that switch to lowsulfur coal often experience higher ash loading and lower fly ash resistivity, resulting in higher stack opacity. Many of these power plants add small concentrations of SO 3 from the oxidation of elemental sulfur to lower resistivity and improve ash collection in the electrostatic precipitator. While this technique may avoid some expense of retrofitting additional precipitator collection areas, the extra SO 3 can lead to the formation of a "blue plume" and release acid rain precursors. This paper shows that SO 2 existing in the flue gas could be used to produce sufficient SO 3 through a combustion-based process immediately upstream of the electrostatic precipitator. This technique also humidifies the flue gas, which may further enhance precipitator performance.

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“…The presence of SO2 has been reported to catalyze H atom removal at medium to high temperatures in rich, premixed laminar flames [1,2,3,4,5,6,7] and laboratory reactors [8,9]. The mechanism for radical removal is commonly recognized to be of the type, X+SO2+M→XSO2+M, Y+XSO2→XY+SO2, where X and Y may be H, O, or OH.…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of radical removal by SO2

Rasmussen

Glarborg

Marshall

2007

Proceedings of the Combustion Institute

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It is well established from experiments in premixed, laminar flames, jet-stirred reactors, flow reactors, and batch reactors that SO2 acts to catalyze hydrogen atom removal at stoichiometric and reducing conditions. However, the commonly accepted mechanism for radical removal, SO2 + H(+M) HOSO(+M), HOSO + H/OH SO2 + H2/H2O, has been challenged by recent theoretical and experimental results. Based on ab initio calculations for key reactions, we update the kinetic model for this chemistry and re-examine the mechanism of fuel/SO2 interactions. We find that the interaction of SO2 with the radical pool is more complex than previously assumed, involving HOSO and SO, as well as, at high temperatures also HSO, SH and S. The revised mechanism with a high rate constant for H+SO2 recombination and with SO+H2O, rather than SO2+H2, as major products of the HOSO+H reaction is in agreement with a range of experimental results from batch and flow reactors, as well as laminar flames.

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Sulfur in the Burnt Gas of Hydrogen-Oxygen Flames

Cited by 63 publications

References 0 publications

Reactions of SO₃ with the O/H Radical Pool under Combustion Conditions

Reactions of SO₃ with the O/H Radical Pool under Combustion Conditions

An Alternative to Additional SO₃ Injection for Fly Ash Conditioning

Mechanisms of radical removal by SO2

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Sulfur in the Burnt Gas of Hydrogen-Oxygen Flames

Cited by 63 publications

References 0 publications

Reactions of SO3 with the O/H Radical Pool under Combustion Conditions

Reactions of SO3 with the O/H Radical Pool under Combustion Conditions

An Alternative to Additional SO3 Injection for Fly Ash Conditioning

Mechanisms of radical removal by SO2

Contact Info

Product

Resources

About

Reactions of SO₃ with the O/H Radical Pool under Combustion Conditions

Reactions of SO₃ with the O/H Radical Pool under Combustion Conditions

An Alternative to Additional SO₃ Injection for Fly Ash Conditioning