Numerical modeling of heat transfer characteristics in a two-pass oxygen transport reactor for fire tube boilers under oxy-fuel combustion

Mansir, Ibrahim B.; Ben‐Mansour, Rached; Habib, Mohamed A.

doi:10.1016/j.applthermaleng.2021.117248

Cited by 12 publications

(4 citation statements)

References 45 publications

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“…A series of CFD simulations were conducted on the commercial software ANSYS FLUENT, as a common method in studies on combustion characteristics in boiler (Mansir et al, 2021;Jin et al, 2022). Reynolds-Averaged-Numerical-Simulation (RANS) was conducted where the variables in a turbulent flow are assumed as averaged or mean quantities (Amani et al, 2019).…”

Section: Governing Equationsmentioning

confidence: 99%

Effects of hydrogen addition on NOx formation in a non-premixed methane low-NOx combustor

CHENG,

ZHU,

DENG

2024

Mechanical Engineering Journal

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Hydrogen is a promising carbon-free fuel, but nitric oxides (NO x ) emissions are significantly increased with higher temperature in hydrogen combustion. Internal flue gas recirculation (IFGR) is one of the most effective NO x reduction techniques in boilers. Previous research has widely reported NO x generation with hydrogen enrichments from a chemical kinetic perspective, however, the NO x formation principles in non-premixed methane/air combustion using IFGR with hydrogen addition are still unclear. This work aims to investigate the effects of hydrogen addition on NO x formation in a non-premixed methane low-NO x combustor using IFGR. The Reynolds-averaged Navier-Stokes (RANS) simulations were conducted on a 5 kW non-premixed combustor with IFGR rate of 17.7%, which generated 11.3 mg/m 3 of total NO x generation in methane combustion. A series of three-dimensional computational fluid dynamics (CFD) simulations with detailed mechanisms was tested on four hydrogen power fractions. The reaction intensities of the main NO x formation pathways were analyzed on reaction rates. The results show that 70% hydrogen power fractions lead to significantly greater NO x concentration to 677.8 mg/m 3 , as high as 60 times of the original concentration. With no additional techniques, the original methane low-NO x combustor is only allowed for hydrogen addition of less than 20% power fraction. The NNH route becomes the second dominant pathway in hydrogen-added flames. Influenced by the growing hydrogen contents, the generation of the NNH route is largely generated from 2 mg/m 3 to 65 mg/m 3 . This work connects the hydrogen addition and the NO x formation pathways in non-premixed methane combustion, and highlights the importance of eliminating thermal NO x and the NNH route to achieve low-NO x combustion rather than sole NO x suppression method, which can provide a reference for designing low-NO x techniques.

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Section: Governing Equationsmentioning

confidence: 99%

Effects of hydrogen addition on NOx formation in a non-premixed methane low-NOx combustor

CHENG,

ZHU,

DENG

2024

Mechanical Engineering Journal

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“…Ben-Mansour et al [18] compared air combustion and oxy-fuel FGR combustion in a water tube boiler. Mansir et al [19] and Ahn et al [20] compared the two combustion methods in a fire tube boiler. FGR can further decrease the flame temperature, helping to mitigate issues such as high-temperature corrosion and thermal NOx formation [21].…”

Section: Introductionmentioning

confidence: 99%

“…The aforementioned studies [16][17][18][19][20][21] focused on the combustion chamber's flame and heat transfer characteristics. However, to successfully retrofit oxy-fuel combustion into existing industrial boilers, it is essential to consider heat transfer in components beyond the combustion chamber.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer and Thermal Efficiency in Oxy-Fuel Retrofit of 0.5 MW Fire Tube Gas Boiler

Ahn

2024

Processes

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Industrial boilers cause significant energy wastage that could be mitigated with oxy-fuel combustion versus traditional air combustion. Despite several feasibility studies on oxy-fuel burners, they are widely avoided in industry due to major infrastructural challenges. This study measured the performance and heat transfer characteristics of each component in a 0.5 MW fire tube gas boiler after retrofitting it with an oxy-fuel burner. Comparisons were drawn across three combustion modes—air combustion, oxy-fuel combustion, and oxy-fuel flue gas recirculation (FGR). The Dittus–Boelter equation was employed to predict heat transfer in the fire tube for all combustion modes at full load (100%). Heat transfer in the latent heat section of the economizer was measured and compared with predictions using the Zukauskas equation. With this retrofit, oxy-fuel combustion improved the thermal efficiency by about 3–4%. In oxy-fuel combustion, the flow rate of exhaust gas decreased. When integrated into an existing fire tube boiler, the fire tube’s heat transfer contribution diminished greatly, suggesting the economic viability of a redesigned, reduced fire tube section. Additionally, a new design could address the notable increase in gas radiation from the fire tube in oxy-fuel and FGR, as well as aid in the efficient recovery of condensation heat from exhaust gases.

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“…IB. Mansir et al [13,14] proposed a two-pass methane combustion reactor used in a fire tube boiler which can generate 1-5 MW power, and numerically investigated the effects of the emissivity and thermal conductivity of materials on the heat transfer behavior of the reactor.…”

Section: Introductionmentioning

confidence: 99%

CFD Simulation of Syngas Combustion in a Two-Pass Oxygen Transport Membrane Reactor for Fire Tube Boiler Application

Zhao

Chen

2021

Energies

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The oxygen transport membrane reactor technology enables the stable combustion of syngas and reduction in NOx emission. Applying the syngas combustion membrane reactor to fire tube boiler can integrate oxygen separation, syngas combustion, and steam generation in a single apparatus. In this study, a CFD model for oxygen permeation and syngas combustion in a two-pass LSCoF-6428 tubular membrane reactor for fire tube boiler application was developed to study the effects of the inlet temperature, the sweep gas flow rate, and the syngas composition on the reactor performance. It is shown that the inlet temperature has a strong effect on the reactor performance. Increasing the inlet temperature can efficiently and significantly improve the oxygen permeability and the heat production capacity. A 34-times increase of oxygen permeation rate and a doubled thermal power output can be obtained when increasing the inlet temperature from 1073 to 1273 K. The membrane temperature, the oxygen permeation rate, and the thermal power output of the reactor all increase with the increase of sweep gas flow rate or H2/CO mass ratio in syngas. The feasibility of the syngas combustion membrane reactor for fire tube boiler application was elucidated.

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Numerical modeling of heat transfer characteristics in a two-pass oxygen transport reactor for fire tube boilers under oxy-fuel combustion

Cited by 12 publications

References 45 publications

Effects of hydrogen addition on NO<i><sub>x</sub></i> formation in a non-premixed methane low-NO<i><sub>x</sub></i> combustor

Effects of hydrogen addition on NO<i><sub>x</sub></i> formation in a non-premixed methane low-NO<i><sub>x</sub></i> combustor

Heat Transfer and Thermal Efficiency in Oxy-Fuel Retrofit of 0.5 MW Fire Tube Gas Boiler

CFD Simulation of Syngas Combustion in a Two-Pass Oxygen Transport Membrane Reactor for Fire Tube Boiler Application

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