Enhancement of hydrogen sulfide oxidation via excitation of oxygen molecules to the singlet delta state

Starik, A. M.; Savelieva, V. A.; Sharipov, Alexander S.; Титова, Н. С.

doi:10.1016/j.combustflame.2016.05.014

Cited by 16 publications

(5 citation statements)

References 41 publications

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“…However, the reaction barrier for the initial step is too high for it to be important under the current conditions. Another possibility, as suggested by Starik et al [72], is that reaction of H 2 S with the tiny equilibrium population of singlet oxygen may promote [94] was obtained for quartet transition state. For completeness, we did TST calculations also via the doublet TS.…”

Section: Detailed Kinetic Modelmentioning

confidence: 99%

An Exploratory Flow Reactor Study of H₂S Oxidation at 30–100 Bar

Song

Hashemi

Christensen

et al. 2016

Int J of Chemical Kinetics

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Hydrogen sulfide oxidation experiments were conducted in O2/N2 at high pressure (30 and 100 bar) under oxidizing and stoichiometric conditions. Temperatures ranged from 450 to 925 K, with residence times of 3–20 s. Under stoichiometric conditions, the oxidation of H2S was initiated at 600 K and almost completed at 900 K. Under oxidizing conditions, the onset temperature for reaction was 500–550 K, depending on pressure and residence time, with full oxidization to SO2 at 550–600 K. Similar results were obtained in quartz and alumina tubes, indicating little influence of surface chemistry. The data were interpreted in terms of a detailed chemical kinetic model. The rate constants for selected reactions, including SH + O2 ⇄ SO2 + H, were determined from ab initio calculations. Modeling predictions generally overpredicted the temperature for onset of reaction. Calculations were sensitive to reactions of the comparatively unreactive SH radical. Under stoichiometric conditions, the oxidation rate was mostly controlled by the SH + SH branching ratio to form H2S + S (promoting reaction) and HSSH (terminating). Further work is desirable on the SH + SH recombination and on subsequent reactions in the S2 subset of the mechanism. Under oxidizing conditions, a high O2 concentration (augmented by the high pressure) causes the termolecular reaction SH + O2 + O2 → HSO + O3 to become the major consumption step for SH, according to the model. Consequently, calculations become very sensitive to the rate constant and product channels for the H2S + O3 reaction, which are currently not well established.

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Section: Detailed Kinetic Modelmentioning

confidence: 99%

An Exploratory Flow Reactor Study of H₂S Oxidation at 30–100 Bar

Song

Hashemi

Christensen

et al. 2016

Int J of Chemical Kinetics

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“…For the numerical study of H2S-H2O-air mixture conversion in a flow reactor, the reaction mechanism [3] was taken as a basic one. This mechanism was supplemented by the reactions with participation of O2(a 1 Δg) and O2(b 1 Σg + ) molecules which were taken from [10]. Fig.…”

Section: Methodsmentioning

confidence: 99%

Numerical study of H₂S-H₂O-air mixture conversion to hydrogen via activation of air by an electric discharge

2018

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The numerical analysis of H2 production during partial oxidation of H2S–H2O–air in a plug-flow reactor at a rather low temperature (T 0=500 K) was conducted. For the reforming process promotion, the oxidizer (air) was activated by an electrical discharge with different values of reduced electric field E/N and input energy E s. It was shown that a significant hydrogen yield in a flow reactor can be obtained only after mixture ignition. The ignition delay length turned out to be minimal at E/N~4–10 and 120–150 Td, when O2(a1Δg) mole fraction in the discharge products is maximal. If the H2S–H2O–air mixture ignites inside the flow reactor, the H2 mole fraction and its relative yield do not depend on E/N. The relative hydrogen yield increases monotonically with an increase of H2O amount. The specific energy requirement for H2 production in considered process was evaluated.

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“…The base mechanism was developed on the basis of Zhou et al’s mechanism. The mechanism contains the updated rate parameters for the initiation channel, H 2 S + O 2 , proposed by Starik et al A comparison of the experimental data with model predictions using the adopted mechanism in this work and some of the recently proposed mechanisms by Gersen et al and Colom-Díaz et al is shown in Figure . In general, all the models satisfactorily captured the experimentally observed profiles of H 2 S oxidation and SO 2 formation in a flow reactor.…”

Section: Reaction Mechanism Developmentmentioning

confidence: 99%

“…However, some uncertainties still remain regarding the kinetics of H 2 S/SH oxidation reactions (including HS + O 2 , H 2 S + HO 2 , and H 2 S + O 2 ), whose rate parameters were estimated in Zhou et al based on similar reactions. Starik et al , conducted ab-initio calculations and revealed the importance of the initiation reaction, H 2 S + O 2 ⇌ HS + HO 2 , (ignored in the H 2 S oxidation mechanisms) in predicting satisfactorily a wide range of experimental data on laminar burning velocity and ignition delay. They published a revised mechanism for H 2 S oxidation containing 27 species and 233 reactions.…”

Section: Introductionmentioning

confidence: 99%

Detailed Reaction Mechanism To Predict Ammonia Destruction in the Thermal Section of Sulfur Recovery Units

Ibrahim

Hamadi

Raj

2020

Ind. Eng. Chem. Res.

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Ammonia and aromatics such as benzene, toluene, and xylene are typically found in acid gas and sour water stripper gas in oil and gas processing plants and gasification facilities. This gas is often processed in sulfur recovery units (SRUs) to recover marketable sulfur and thermal energy. Ammonia must be completely oxidized at high temperatures in the furnace to prevent the plugging of catalytic reactors and the corrosion of downstream equipment in the SRU. In this paper, a detailed reaction mechanism is presented to capture the chemistry of ammonia destruction in the presence of several chemically active species of acid gas combustion in the thermal section of SRUs. The mechanism is validated with different sets of experimental data from lab-scale and industrial plant studies. The reaction mechanism is utilized to simulate the furnace and the waste heat boiler (WHB) of SRUs in CHEMKIN PRO software. Through the furnace and WHB simulations, the most suitable operating conditions of the furnace that could lead to an effective destruction of ammonia in the furnace is investigated, and the dominant reaction pathways involved in the oxidation process are identified. With increasing feed temperature and oxygen concentration in air, the ammonia concentration was found to decrease substantially down to an acceptable limit of <150 ppm at the exit of the thermal section of SRUs. The decrease in NH 3 occurred because of its enhanced oxidation by several oxidants (OH, SO, and O 2 ) at high temperatures above 1300 °C, though it also led to a decrease in sulfur recovery efficiency and an increase in CO production at the exit of the thermal section. This indicates the need for optimized furnace parameters that could lead to a reasonable trade-off between ammonia destruction and CO emissions from the SRU. The developed reaction mechanism provides a way to obtain optimized SRU parameters to achieve ammonia destruction, enhanced catalyst life, and reduced emission of harmful gases (CO and SO 2 ).

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Enhancement of hydrogen sulfide oxidation via excitation of oxygen molecules to the singlet delta state

Cited by 16 publications

References 41 publications

An Exploratory Flow Reactor Study of H₂S Oxidation at 30–100 Bar

An Exploratory Flow Reactor Study of H₂S Oxidation at 30–100 Bar

Numerical study of H₂S-H₂O-air mixture conversion to hydrogen via activation of air by an electric discharge

Detailed Reaction Mechanism To Predict Ammonia Destruction in the Thermal Section of Sulfur Recovery Units

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Enhancement of hydrogen sulfide oxidation via excitation of oxygen molecules to the singlet delta state

Cited by 16 publications

References 41 publications

An Exploratory Flow Reactor Study of H2S Oxidation at 30–100 Bar

An Exploratory Flow Reactor Study of H2S Oxidation at 30–100 Bar

Numerical study of H2S-H2O-air mixture conversion to hydrogen via activation of air by an electric discharge

Detailed Reaction Mechanism To Predict Ammonia Destruction in the Thermal Section of Sulfur Recovery Units

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Product

Resources

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An Exploratory Flow Reactor Study of H₂S Oxidation at 30–100 Bar

An Exploratory Flow Reactor Study of H₂S Oxidation at 30–100 Bar

Numerical study of H₂S-H₂O-air mixture conversion to hydrogen via activation of air by an electric discharge