Effects of flue gas recirculation on self-excited combustion instability and NOx emission of a premixed flame

Pan, Deng; Zhu, Tong; Ji, Chenzhen; Ke, Enlei

doi:10.1016/j.tsep.2022.101252

Cited by 15 publications

(8 citation statements)

References 33 publications

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“…recirculation performance is often evaluated by the FGR rate, the mass flow rate of recirculated flue gas to the burnt gas without recirculation (Shi et al, 2018;Pan et al, 2022). A typical FGR rate of 13% can remove half of NO emissions (Shi et al, 2018).…”

Section: Effects Of Hydrogen Addition On No X Formation In a Nonpremi...mentioning

confidence: 99%

“…An FGR rate higher than 20% may cause unstable combustion. FGR is classified as external flue gas recirculation (EFGR) (Pan et al, 2022) and internal flue gas recirculation (IFGR) (Fąfara and Modliński, 2022), depends on whether part of flue gas is recirculated outside or inside of the furnace. Due to the inconvenient transformation, IFGR has not received sufficient focus in contrast to EFGR.…”

Section: Effects Of Hydrogen Addition On No X Formation In a Nonpremi...mentioning

confidence: 99%

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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: Effects Of Hydrogen Addition On No X Formation In a Nonpremi...mentioning

confidence: 99%

Section: Effects Of Hydrogen Addition On No X Formation In a Nonpremi...mentioning

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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“…In summary, most of the studies have focused on the effect of equivalence ratio or oxygen enrichment on combustion instability, and there are few studies on the law of influence of lower oxygen content on the combustion instability phenomenon. Due to the improvement of emission requirements for gas turbine combustion chambers, flue gas recirculation technology can reduce pollutant emissions from combustion [30][31][32][33], but because the flue gas recirculation technology reduces the oxygen content at the combustion chamber inlet [34][35][36], which leads to a more pronounced combustion instability phenomenon [37][38][39], a study on combustion instability at lower oxygen content is needed. Therefore, it is necessary to study the velocity, temperature, OH, pressure pulsation, and exothermic pulsation of the flow field in the combustion chamber at different oxygen contents to determine the effect of low oxygen content on combustion instability.…”

Section: Introductionmentioning

confidence: 99%

Impact of Oxygen Content on Flame Dynamics in a Non-Premixed Gas Turbine Model Combustor

Chen,

Huang,

Wang

et al. 2024

JMSE

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In this study, large eddy simulation (LES) was used to investigate the dynamic characteristics of diffusion flames in a swirl combustion chamber at an oxygen content of 11–23 wt% and temperature of 770 K. The proper orthogonal decomposition (POD) method was employed to obtain flame dynamic modes. The results indicate that oxygen content has a significant impact on the downstream flow and flame combustion characteristics of the swirl combustion chamber. With oxygen content increasing, the size of the recirculation zone is reduced, and the flame field fluctuations are intensified. The pressure and heat release fluctuations under different oxygen contents were analyzed using frequency spectrum analysis. Finally, the flame modes were analyzed using the POD method, and it was found that the coherent structures are asymmetric relative to the local coordinate system. At an oxygen content of 11 wt%, they exhibit larger coherent structures, while at an oxygen content of 23 wt%, they exhibit numerous turbulent structures.

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“…Mohsen Abdelaal and Medhat El-Riedy et al found that the flame remains stable up to a recirculation level of 40%, but the temperature decreases by about 25%, and the SO X content decreases from 90 to 5 ppm [31]. In this case, combustion instability can be associated with the level of NO X emissions in premix burners [32]. Ehsan Houshfar and colleagues used two different compositions of recirculating flue gases: CO 2 and CO 2 + NO [33].…”

Section: Introductionmentioning

confidence: 99%

Applying the Random Forest Method to Improve Burner Efficiency

et al. 2022

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Fuel power plants are one of the main sources of pollutant emissions, so special attention should be paid to improving the efficiency of the fuel combustion process. The mathematical modeling of processes in the combustion chamber makes it possible to reliably predict and find the best dynamic characteristics of the operation of a power plant, in order to quantify the emission of harmful substances, as well as the environmental and technical and economic efficiency of various regime control actions and measures, and the use of new types of composite fuels. The main purpose of this article is to illustrate how machine learning methods can play an important role in modeling and predicting the performance and control of the combustion process. The paper proposes a mathematical model of an unsteady turbulent combustion process, presents a model of a combustion chamber with a combined burner, and performs a numerical study using the STAR-CCM+ multidisciplinary platform. The influence of various input indicators on the efficiency of burner devices, which is evaluated by several parameters at the output, is investigated. In this case, three possible states of the burners are assumed: optimal, satisfactory and unsatisfactory.

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Effects of flue gas recirculation on self-excited combustion instability and NOx emission of a premixed flame

Cited by 15 publications

References 33 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

Impact of Oxygen Content on Flame Dynamics in a Non-Premixed Gas Turbine Model Combustor

Applying the Random Forest Method to Improve Burner Efficiency

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