Numerical study of hydrogen-enriched methane-air combustion under ultra-lean conditions

Mokheimer, Esmail M. A.; Sanusi, Yinka S.; Habib, Mohamed A.

doi:10.1002/er.3477

Cited by 25 publications

(8 citation statements)

References 47 publications

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“…Alzahrani et al explored the accuracy of a selected set of kinetics and combustion mechanisms for syngas combustion. Mokheimer et al numerically investigated the stability and emission of hydrogen enriched methane under very lean air combustion in a diffusion flam. They developed a combustion mechanism that can closely fit with the experimental results by Sanusi et al From their numerical analysis, Mokheimer et al could determine the optimum equivalence ratio at which the CO emission can be eliminated and NOx emission can be limited below 5 ppm.…”

Section: Trends Of Oxycombustion Technologymentioning

confidence: 99%

Oxy-fuel combustion technology: current status, applications, and trends

Nemitallah

Habib

Badr

et al. 2017

Int. J. Energy Res.

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117

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Summary The increased level of emissions of carbon dioxide into the atmosphere due to burning of fossil fuels represents one of the main barriers toward the reduction of greenhouse gases and the control of global warming. In the last decades, the use of renewable and clean sources of energies such as solar and wind energies has been increased extensively. However, due to the tremendously increasing world energy demand, fossil fuels would continue in use for decades which necessitates the integration of carbon capture technologies (CCTs) in power plants. These technologies include oxycombustion, pre‐combustion, and post‐combustion carbon capture. Oxycombustion technology is one of the most promising carbon capture technologies as it can be applied with slight modifications to existing power plants or to new power plants. In this technology, fuel is burned using an oxidizer mixture of pure oxygen plus recycled exhaust gases (consists mainly of CO2). The oxycombustion process results in highly CO2‐concentrated exhaust gases, which facilitates the capture process of CO2 after H2O condensation. The captured CO2 can be used for industrial applications or can be sequestrated. The current work reviews the current status of oxycombustion technology and its applications in existing conventional combustion systems (including gas turbines and boilers) and novel oxygen transport reactors (OTRs). The review starts with an introduction to the available CCTs with emphasis on their different applications and limitations of use, followed by a review on oxycombustion applications in different combustion systems utilizing gaseous, liquid, and coal fuels. The current status and technology readiness level of oxycombustion technology is discussed. The novel application of oxycombustion technology in OTRs is analyzed in some details. The analyses of OTRs include oxygen permeation technique, fabrication of oxygen transport membranes (OTMs), calculation of oxygen permeation flux, and coupling between oxygen separation and oxycombustion of fuel within the same unit called OTR. The oxycombustion process inside OTR is analyzed considering coal and gaseous fuels. The future trends of oxycombustion technology are itemized and discussed in details in the present study including: (i) ITMs for syngas production; (ii) combustion utilizing liquid fuels in OTRs; (iii) oxy‐combustion integrated power plants and (iv) third generation technologies for CO2 capture. Techno‐economic analysis of oxycombustion integrated systems is also discussed trying to assess the future prospects of this technology. Copyright © 2017 John Wiley & Sons, Ltd.

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Section: Trends Of Oxycombustion Technologymentioning

confidence: 99%

Oxy-fuel combustion technology: current status, applications, and trends

Nemitallah

Habib

Badr

et al. 2017

Int. J. Energy Res.

Self Cite

117

View full text Add to dashboard Cite

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“…We, therefore, adopted this kinetic scheme to model the combustion zone in the MRCR. The global reaction mechanism of methane by Westbrook has been reported to give a satisfactory prediction of methane‐air flame . This mechanism, given in Table , was used to account for the oxidation of the un‐reformed methane.…”

Section: Numerical Modelmentioning

confidence: 99%

Performance analysis of a membrane‐based reformer‐combustor reactor for hydrogen generation

Sanusi

Mokheimer

2018

Int J Energy Res

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Summary Hydrogen is mostly produced in conventional steam methane reforming plants. In this work, we proposed a membrane‐based reformer‐combustor reactor (MRCR) for hydrogen generation in order to improve heat recovery and overall thermal efficiency. The proposed configuration will also reduce the complexity in existing steam methane reforming (SMR) plants. The proposed MRCR comprises combustion zone, hydrogen permeate zone, and SMR zone. A computational fluid dynamics model was developed using ANSYS‐Fluent software to simulate and analyze the performance of the proposed MRCR. Results show that high hydrogen yields were observed at high reformer pressures (RPs) and low gas hourly space velocities (GHSVs). Furthermore, by increasing the steam to methane ratio and addition of excess air in the combustion side, the hydrogen yield from the MRCR decreases. This is attributed to the reduction in the effective temperature of the hydrogen membrane. High RP, low GHSV, and low steam to methane ratio that increased the hydrogen yield also decreased carbon monoxide (CO) emissions. For an increased RP from 1 to 10 bar, the CO emission decreased by about 99%. The reduction in CO emission at high RP would be attributed to the effect of water gas shift reaction in the MRCR. Results of the extensive parametric study presented in this work can be used to determine the operating conditions based on tradeoffs between hydrogen yield (mole H2/mole CH4), hydrogen production rate (kg of H2/h), allowable CO emissions, and exhaust gas temperature for other applications such as gas turbine.

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“…CFD combustion study enables researcher to get more insight on the flame dynamics in a cheaper and safer way. It has been used by various researchers [29][30][31] in the prediction of combustion and emission characteristics.…”

Section: Introductionmentioning

confidence: 99%

Effect of different syngas compositions on the combustion characteristics and emission of a model combustor

Sanusi¹,

Dandajeh²

2020

Nig. J. Tech.

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There is a growing need to design fuel flexible combustors. This require understanding of the combustion and emission characteristics of the combustors under varying fuel compositions. In the present study, the combustion characteristics and emission of methane and syngas flames were investigated numerically in a swirl stabilized combustor. The numerical model was developed using ANSYS-fluent software and validated using experimental values of temperature, CO2 and NOx emissions. A two-step chemical mechanism was used to model methane-air combustion. Results of the numerical validation showed similar trend between the experimental and predicted temperature along the combustor axis with about 5 % over prediction of the temperature. Syngas-air combustion was thereafter modeled using a 21 step chemical mechanism. Syngas compositions studied were: syngas A (67% CO: 33% H2), syngas B (50% CO: 50% H2) and syngas C (33% CO: 67% H2). Results showed that for pure methane, a V-shaped flame was observed with the flame attached to the fuel nozzle, while a lifted flame was observed for case of syngas A composition. CO gas with higher ignition temperature and flammability as compared to H2 gas is the dominant gas in syngas A fuel composition. Jet flames were observed for syngas B and syngas C. Carbon monoxide is a slow burning gas. Therefore syngas with low CO content has a low tendency of emission of CO from the combustor. This suggests that syngas with high CO content such syngas A may require more residence time to completely combust the CO gas. The NOx emission was observed to have the same trend as that of the combustor maximum temperature. Syngas C flame had the highest NOx emission, while, syngas A flame had no NOx emission. This is due to low combustor temperature observed in the case of syngas A flame. Keywords: Syngas, ANSYS-FLUENT, Swirl-stabilized combustor, NOx emission, Chemical Mechanism

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Numerical study of hydrogen-enriched methane-air combustion under ultra-lean conditions

Cited by 25 publications

References 47 publications

Oxy-fuel combustion technology: current status, applications, and trends

Oxy-fuel combustion technology: current status, applications, and trends

Performance analysis of a membrane‐based reformer‐combustor reactor for hydrogen generation

Effect of different syngas compositions on the combustion characteristics and emission of a model combustor

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