Oxy-fuel combustion in a two-pass oxygen transport reactor for fire tube boiler application

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

doi:10.1016/j.apenergy.2018.08.057

Cited by 12 publications

(11 citation statements)

References 41 publications

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“…These two features are crucial for better performance of the membrane when the results are projected on the case of membrane reactor operation. For the case of OTMRs, membranes should be kept at higher temperature (from 650°C to 950°C) to be activated for oxygen permeation . As shown in Figure , the temperature beside the porous plate surface is in the range of 800 K to 1600 K, which is a good range for operation of the membrane when the results are projected on the case of OTMRs operation.…”

Section: Resultsmentioning

confidence: 99%

“…However, a limited number of experimental investigations have been performed on OTMRs under oxy‐fuel combustion conditions for CO 2 capture purposes. The operation of the OTMRs has some limitations in terms of low oxygen permeation flux for complete conversion of the fuel, membrane contamination and sensitivity to some gases especially CO 2 and H 2 O, and limited operating range of temperature before thermal cracking (<950°C) . Such limitations restrict the possibility of studying the oxy‐combustion characteristics and oxy‐flame stability within OTMRs under real reacting conditions.…”

Section: Introductionmentioning

confidence: 99%

“…Successful application of oxycombustion in OTMRs is the main goal that should allow the replacement of conventional burners by ceramic membrane reactors, where oxygen separation and in situ oxy-fuel burning occur within the same unit. Such replacement of conventional burners by OTMRs has been investigated numerically in a number of studies [20][21][22][23][24] ; however, experimental investigations are rare. 25 A limited number of studies have been performed to demonstrate the performance of ceramic membranes on the industrial level.…”

Section: Introductionmentioning

confidence: 99%

“…The operation of the OTMRs has some limitations in terms of low oxygen permeation flux for complete conversion of the fuel, membrane contamination and sensitivity to some gases especially CO 2 and H 2 O, [26][27][28][29][30] and limited operating range of temperature before thermal cracking (<950°C). 24,25 Such limitations restrict the possibility of studying the oxy-combustion characteristics and oxy-flame stability within OTMRs under real reacting conditions. Still, oxygen transport membranes are under development for higher oxygen permeation flux and stability under oxy-combustion conditions, and they are of great potential for industrial application in the near future.…”

Section: Introductionmentioning

confidence: 99%

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Experimental and numerical study of oxy‐methane flames in a porous‐plate reactor mimicking membrane reactor operation

2019

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Summary The work investigates the reacting flow field, oxy‐methane flame characteristics and location, and the species distributions in a porous‐plate reactor mimicking the operation of oxygen transport membrane reactors (OTMRs). The study was performed experimentally and numerically considering ranges of operating equivalence ratio, from 0.5 to 1.0, and CO2 concentrations in the total oxidizer flow (O2 and CO2), from 0% to 55% (by Vol). Oxygen was supplied through a slightly pressurized top and bottom chambers to cross the two porous plates to the central chamber, where a premixed mixture of CH4 and CO2 is introduced. ANSYS Fluent 17.1 software was used to solve for conservation and radiative transfer equations in the full three‐dimensional (3‐D) domain. The modified Westbrook‐Dryer (Oxy‐WD) two‐step reduced mechanism for oxy‐methane combustion was adapted for the calculations of chemical kinetics. The captured flame shapes using a high‐speed camera were compared with the calculated ones, and the results showed good agreements. At fixed equivalence ratio, elongated flames were obtained at higher CO2 concentrations due to the increase in the mainstream Reynolds number and reduction in reaction rates, which delays the completeness of combustion. At fixed CO2 concentration, the increase in equivalence ratio resulted in more compact and intense flames. The effective mixing and flame stability resulted in complete fuel conversion under stoichiometric condition. Stable flames were located between the two porous plates at reasonable distance. This perfect flame location prevents the thermal fracture of the membranes and improves their oxygen permeation flux, resulting in better combustion characteristics when the results are projected on the case of OTMRs. This implies efficient and safe applicability of the OTMRs by the condition that membranes can provide sufficient oxygen flux for complete combustion. A warm outer recirculation zone (ORZ) was created beside each porous plate, which helps anchoring the flame at the leading edge of the porous plate. The range of temperature within the ORZ was 800 to 1600 K, which lies in the operability limits of membranes for the case of OTMRs. The effective complete mixing and flame stability resulted in complete fuel conversion under stoichiometric condition. The temperature and species distributions within the reactor are presented in detail over wide ranges of operating conditions. The results recommended the reactor operation under stoichiometric combustion condition based on performance and economic points of views. The results are promising when projected on the application of the OTMRs under oxy‐combustion conditions for clean and efficient energy production.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Experimental and numerical study of oxy‐methane flames in a porous‐plate reactor mimicking membrane reactor operation

2019

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“…Owing to the increasing attention given to new carbon capture and storage (CCS) technologies, cleaner and more efficient techniques, such as oxygen-fired combustion, and chemical looping combustion, have been implemented in CFB boilers. In oxygen-fired CFB boilers, the fuel is burned with a mixture of pure oxygen and recycled flue gas [28]. The higher level of radiating gases in oxygen fired combustion limits the use of spectral radiation models, which are developed for conventional air-fired combustion systems [3,6,4].…”

Section: Introductionmentioning

confidence: 99%

Improved banded method for spectral thermal radiation in participating media with spectrally dependent wall emittance

2019

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To develop an efficient and practical spectral radiation model for CFD simulations, a banded approach is proposed for a mixture of carbon dioxide and water vapor in varying thermodynamic states. Using a previously reported band dividing scheme, a statistical narrow band model is implemented to provide gray band absorption coefficient databases. The databases were then approximated by certain simple correlations, which can be readily used in CFD calculations of RTE solvers. The correlations were validated in several 1D and 3D benchmarks representing various combustion conditions. The accuracy and CPU cost of the proposed banded approach were studied and compared with those of other similar methods. The results demonstrated that the new approach is an efficient and accurate method that can be conveniently applied in a commercial CFD code for spectral radiation; moreover, it can handle non-gray walls. As a practical case study, the proposed approach was used to simulate radiative heat transfer within a back pass channel of a CFB boiler. The effect of combustion scenarios, i.e., air-and oxygen-fired, boiler load, inlet flow conditions, and wall material, was analyzed by the CFD model. The predictions of two different RTE solvers, i.e., P1 and DO, and the required CPU time were compared for gray and non-gray models.

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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

Mansir

Ben‐Mansour

Habib

2021

Applied Thermal Engineering

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Oxy-fuel combustion in a two-pass oxygen transport reactor for fire tube boiler application

Cited by 12 publications

References 41 publications

Experimental and numerical study of oxy‐methane flames in a porous‐plate reactor mimicking membrane reactor operation

Experimental and numerical study of oxy‐methane flames in a porous‐plate reactor mimicking membrane reactor operation

Improved banded method for spectral thermal radiation in participating media with spectrally dependent wall emittance

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

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