CFD investigation on combustion and NO emission characteristics in a 600 MW wall-fired boiler under high temperature and strong reducing atmosphere

Du, Yongbo; Wang, Chang‐An; Lv, Qiang; Li, Debo; Liu, Hu; Che, Defu

doi:10.1016/j.applthermaleng.2017.07.147

Cited by 64 publications

(29 citation statements)

References 40 publications

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“…Then, these NO x can get a higher reduction in the primary zone since the residence time is longer. 15 Besides, injecting semi-coke from the lower layers increases the density of unburned carbon in the bottom and middle of the burner zone, which can effectively promote the reduction of NO x . 25 Therefore, the NO x emission in case 5 decreases evidently from case 4, and it is even lower than case 3.…”

Section: Resultsmentioning

confidence: 99%

“…This is different from the conventional coal-fired condition, in which the NO concentration generally gets declined through this zone, even though the air coefficient of primary zone is as high as 0.9. 15,27 In the primary zone, co-firing semi-coke could partly postpone the char combustion, which should mostly occur near the burners when firing bituminous coal. Since the char of semi-coke contains the majority of fuel-N, the char combustion would generate a considerable quality NO in this zone, which should be larger than the reduction rate of the upstream NO.…”

Section: Resultsmentioning

confidence: 99%

“…The rate of devolatilization and char combustion was respectively calculated by the two-competing-reactions model and the kinetics/diffusion-limited model. 15,17 The finite-rate/eddy-dissipation model was adopted to describe the turbulence–chemistry interaction for gas phase, and the gas-phase reaction was represented by the following four reactions 18 …”

Section: Modelling Methodologymentioning

confidence: 99%

“…1,13,14 The P-1 model was employed for the radiation heat transfer, with the number of bands set to zero, since it is reasonable to assume that only gray radiation exists in furnace. 15,16 The movement of particles was modeled by Lagrangian method, and the interaction in radiation between particles and gas was included. The rate of devolatilization and char combustion was respectively calculated by the two-competing-reactions model and the kinetics/ diffusion-limited model.…”

Section: Sub-models In Cfd Studymentioning

confidence: 99%

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Computational fluid dynamics investigation on the effect of co-firing semi-coke and bituminous coal in a 300 MW tangentially fired boiler

Wang

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part A:

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In this paper, the effect of co-firing semi-coke in a 300 MW tangentially fired boiler was numerically investigated. The results indicate that the incomplete combustion heat loss and NO x emission both increase with semi-coke co-fired ratio. Semi-coke may be injected into the furnace at a different height, which can lead to different thermal efficiency and NO x emission. It is suggested that semi-coke should not be fed from the top or bottom layer burners, since this could give rise to high carbon content respectively in fly ash and bottom slag. In addition, injecting semi-coke from the top burners could significantly increase the NO x emission. Under 1/2 co-firing ratio, the optimal fuel allocation is that feeding semi-coke from the B, D, and E layer burners. The growth in semi-coke particle size could increase the unburned carbon loss and NO x emission. It is highly recommended to reduce the unburned carbon loss under semi-coke co-fired condition by increasing the stoichiometric ratio of primary air for semi-coke. As it is increased from 0.25 to 0.3, the combustion efficiency of the co-fired condition is 99.47%, the same as when only firing bituminous coal, and the NO x emission is about 30% higher.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Modelling Methodologymentioning

confidence: 99%

Section: Sub-models In Cfd Studymentioning

confidence: 99%

See 2 more Smart Citations

Computational fluid dynamics investigation on the effect of co-firing semi-coke and bituminous coal in a 300 MW tangentially fired boiler

Wang

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part A:

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“…The governing equations are the mass and energy conservation equations as follows: is calculated using Eq. (1) or (2), Cp, p is the specific heat of coal particle, and Qconv, Qtrad, and Qreac are the amounts of convective, radiative, and reaction heat transfers, respectively, and were calculated using the following equations.Qconv = h* (Tg -Tp)Sp(10)…”

mentioning

confidence: 99%

Extending Semi-parallel Reaction Model of Pulverized Coal Particle to Various Coal Types

Akaotsu

Ishimoda

Saito

et al. 2019

J. Jpn. Inst. Energy

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A new concept for modeling the overlap between devolatilization and char oxidation was extended to various coal types. Quasi-steady mass transfer analysis around a single coal particle with devolatilization was performed, and the overlap between devolatilization and char oxidation was modeled with a semi-parallel reaction model. The semi-parallel reaction model can capture the differences in the char oxidation rates of each coal by a single fitting parameter called the inhibition factor. The combustion simulation of the single coal particle indicated the superiority of the semi-parallel reaction model over the previously reported modeling concepts because the semi-parallel reaction model could describe the decrease in char oxidation rate during devolatilization, which is not represented by other reaction models. Although the inhibition factor is not correlated with the proximate analysis of the volatile matter, it is correlated with the temperature at which the rate-controlling step of char oxidation shifts. This is because the proximate analysis does not include information on char reactivity. Therefore, it is suggested that the inhibition effect of devolatilization on char oxidation strongly correlates with the parameter that describes the sensitivity of char oxidation to the mass transfer processes of the oxidant.

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Numerical study on combustion characteristics and heat flux distributions of 660‐MW ultra‐supercritical double‐reheat tower‐type boiler

Deng

Zhang

et al. 2021

Asia-Pacific J Chem Eng

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Ultra‐supercritical double‐reheat technology, as one of the most advanced coal‐fired power generation technology, is an important direction for emission reduction and energy saving in the world. In this study, the numerical calculation was executed in a 660‐MW ultra‐supercritical double‐reheat tower‐type boiler under deep‐air‐staging conditions. The refined HCN oxidation model was adopted to substitute the default model implemented by the user‐defined functions to calculate the NOx emission. The influences of the boiler load, over‐fire air (OFA) ratio, and excess air coefficient on temperature, species, and heat flux distributions were investigated. Results show that the decrement of the boiler load from boiler maximum continuous rating to 50% turbine heat acceptance gives rise to an increase of NOx emission. The heat flux distributions along with the furnace width direction present bell shaped. When the OFA ratio rises from 17% to 43%, NOx emission descends from 357.7 to 179.3 mg m−3 at the furnace outlet, and the heat flux distributions become more uniform along with the furnace width direction with lower peaks. Temperatures, species, and heat flux distributions are similar under the three different excess air coefficients. The NOx emission is the lowest when the excess air coefficient is 1.15. The results could provide a reference for combustion characteristics optimization and hydrodynamic calculation of ultra‐supercritical double‐reheat tower‐type boiler.

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CFD investigation on combustion and NO emission characteristics in a 600 MW wall-fired boiler under high temperature and strong reducing atmosphere

Cited by 64 publications

References 40 publications

Computational fluid dynamics investigation on the effect of co-firing semi-coke and bituminous coal in a 300 MW tangentially fired boiler

Computational fluid dynamics investigation on the effect of co-firing semi-coke and bituminous coal in a 300 MW tangentially fired boiler

Extending Semi-parallel Reaction Model of Pulverized Coal Particle to Various Coal Types

Numerical study on combustion characteristics and heat flux distributions of 660‐MW ultra‐supercritical double‐reheat tower‐type boiler

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