Impact of oxygen enhanced combustion of natural gas on thermal efficiency of combustion aggregate

Dzurňák, Róbert; Jablonský, Gustáv; Varga, Augustín; Kizek, Ján; Pástor, Marcel; Lukáč, Ladislav

doi:10.1051/matecconf/201816807016

Cited by 3 publications

(2 citation statements)

References 2 publications

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“…Often, an increase in the production capacity and plant flexibility is also pursued [32,33]. Considering these goals, several approaches can be adopted, including: -Fuel switch to cleaner and/or cheaper one, often retrofitting fossil fuel boiler to (co-) combustion of natural gas [34], process gases [35], biomass [36,37] or waste fuels [38,39]; -Refitting the existing boilers to oxycombustion [40], which requires installation of an air separation unit for oxygen-enriched air production [41,42] improving fuel burnout, cuts down greenhouse gases emissions [43,44], and can be a pre-requisite to carbon capture from flue gas [45,46]; -Supplementing the existing boilers with a gasification unit [47,48], enabling processing of a wide range of even low-quality materials into combustible gas [49,50]; -Adding a "topping" unit to the existing Rankine cycle unit, usually a gas turbine [51,52], internal combustion engine [53] or a battery of fuel cells [32], resulting in multiple variants of modified plant layout [54]. Each of those variants results in layout reorganization of the remaining plant parts, usually including changes in boiler feedwater train [55,56], boiler air and flue gas fans, and in flue gas and ash handling equipment [57] to boost the energy efficiency even further and to meet the tightening limits of pollutant emissions set by legislation [58].…”

Section: Repowering Of Thermal Power Plants and Industrialmentioning

confidence: 99%

Repowering Industrial Combined Heat and Power Units: a Contribution to Cleaner Energy Production

Variny¹,

Kšiňanová²

2022

Pol. J. Environ. Stud.

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Repowering of industrial combined heat and power units allows reducing industrial greenhouse gases emissions. An existing industrial unit served as model in the gas turbines-based repowering study, aiming at fuel consumption and carbon dioxide emissions reduction. Following unit's model setup and verification, two conservative repowering options (hot windbox and separate gas turbine + heat recovery steam generator) were assessed from economic, energetic, and environmental point of view, including seasonal impact. Hot windbox option leads to annual power production increase by 14.3% (72.8 GWh/year), accompanied by carbon dioxide emissions reduction by 3.9 % (29.5 ktons/year) compared to the base case. The second option delivered more significant power production increase (+261.9 to +298.6 GWh/year) with CO 2 emissions, either slightly higher (+1.5 %) or modestly lower (-4.0%), than in base case depending on heat recovery efficiency from gas turbine exhaust. Both options show feasible economics with simple payback period as low as four years under favorable combination of fuel and electricity prices and CO 2 costs. External CO 2 emissions change due to the change in unit's power production further reduces the total CO 2 emissions, strongly depending on the applied power production emission factor.

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Section: Repowering Of Thermal Power Plants and Industrialmentioning

confidence: 99%

Repowering Industrial Combined Heat and Power Units: a Contribution to Cleaner Energy Production

Variny¹,

Kšiňanová²

2022

Pol. J. Environ. Stud.

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“…burners and, as a consequence, can be employed in various combustion systems [6]. Previous studies have suggested that Lowlevel oxygen enrichment not only costs less among these three enhancement regimes, but has also a positive impact on heating rate increase and fuel saving [3] and efficiency [9] in furnaces, fuel consumption and flue gases reduction in a gas turbine [10], thermal efficiency increase and fuel consumption and unburned hydrocarbons decrease in a diesel engine [11], and a higher combustion efficiency in a combustion chamber with heat exchanger [12]. In such circumstances, noise level will play an important role in the feasibility of using low-level oxygen enhanced systems in burners while it has not been yet addressed in low level OEC or combustion noise studies.…”

Section: Introductionmentioning

confidence: 99%

Large eddy simulation on combustion noise in a non-premixed turbulent free flame: Effect of oxygen enhancement

Ehsaniderakhshan

Mazaheri

Mahmoudi

2020

Energy

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Present work examines the effect of a low-level oxygen concentration enhancement in the oxidizer stream, on the generation of direct combustion noise in a non-premixed turbulent free flame. A hybrid approach utilizing a large eddy simulation, partially stirred reactor combustion model, and Lighthill analogy was employed to predict the sound pressure level in the farfield of the flame. Contributions of different noise sources, including heat release rate and, mole consumption and production rate fluctuations are calculated to predict the sound pressure level in the farfield.Results show that, in comparison to the flame burning with air, the higher temperature in oxygen enhanced flame leads to an increase in the heat release rate and an increase in the rate of consumption and production of the species. The total sound pressure level found to increase by adding oxygen to the oxidizer stream, especially in low frequency ranges. Enhancement of molar oxygen by 10%, increases the noise contribution of the heat release rate fluctuations about 20 dB in low frequency range, and about 10 dB in high frequencies. Additionally, the noise contribution from the mole consumption and production rate decreases about 5 dB in low frequency range and 10 dB in high frequencies.

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Comment on Hamayun et al. Evaluation of Two-Column Air Separation Processes Based on Exergy Analysis. Energies 2020, 13, 6361

2021

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Oxygen production from air belongs to energy-intense processes and, as a result, possibilities for its decrease are a frequent topic of optimization studies, often performed with simulation software such as Aspen Plus or Aspen HYSYS. To obtain veritable results and sound solutions, a suitable calculation method hand in hand with justified assumptions and simplifications should form the base of any such studies. Thus, an analysis of the study by Hamayun et al., Energies 2020, 13, 6361, has been performed, and several weak spots of the study, including oversimplified assumptions, improper selection of a thermodynamic package for simulation and omission of certain technological aspects relevant for energy consumption optimization studies, were identified. For each of the weak spots, a recommendation based on good praxis and relevant scientific literature is provided, and general recommendations are formulated with the hope that this comment will aid all researchers utilizing Aspen Plus and Aspen HYSYS software in their work.

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Impact of oxygen enhanced combustion of natural gas on thermal efficiency of combustion aggregate

Cited by 3 publications

References 2 publications

Repowering Industrial Combined Heat and Power Units: a Contribution to Cleaner Energy Production

Repowering Industrial Combined Heat and Power Units: a Contribution to Cleaner Energy Production

Large eddy simulation on combustion noise in a non-premixed turbulent free flame: Effect of oxygen enhancement

Comment on Hamayun et al. Evaluation of Two-Column Air Separation Processes Based on Exergy Analysis. Energies 2020, 13, 6361

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