Large eddy simulation of pulverized coal combustion in multi-burner system–effect of in-furnace blending method on NO emission

Muto, Masaya; Watanabe, Hiroaki; Kurose, Ryoichi

doi:10.1016/j.apt.2019.09.024

Cited by 23 publications

(7 citation statements)

References 33 publications

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“…Similar treatments can be found in many previous studies. 2,7,8 Finally, the discrepancy of release rate between the N content and CHO content is neglected. Note that the present work focuses on the development of the FPV approach for better NO prediction, thus relatively simple fuel-N composition and distribution are employed without considering the effects of particle thermal history and fuel-N contained species release rate.…”

Section: Methodsmentioning

confidence: 99%

“…Currently, a lot of numerical investigations have been conducted for NO x prediction in pulverized coal flames. − In these studies, the chemical reactions between the major species released from the coal particles and the ambient gas are often described by the global reaction mechanisms − or the mixture fraction method. , The additional global reaction mechanisms of NO x are used for NO x prediction through a postprocessing approach, − which is usually formulated as the functions of species and gas temperature. In this way, minor species cannot be directly obtained from the combustion field and are commonly neglected or treated with equilibrium assumption during the simulations.…”

Section: Introductionmentioning

confidence: 99%

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Hybrid Flamelet/Progress Variable Approach for NO Prediction in Pulverized Coal Flames

et al. 2020

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The flamelet/progress variable (FPV) approach is further extended for a better prediction of NO emission in pulverized coal flames. The predicted results are compared with detailed chemistry simulation solutions for model evaluation. The results show that the original FPV approach with a conventional progress variable consisting of major species can predict the gas temperature and major products well but can roughly predict the NO variation. Therefore, the extended FPV approach with a modified progress variable including both NO and major species is further evaluated. The results indicate that the prediction accuracy of NO is sensitive to the proportion of NO introduced in the modified progress variable. The best prediction of NO can be obtained with the modified progress variable where the concentration of NO is comparable to that of all major species. However, the predictions of other quantities of interest are simultaneously deteriorated to some extent. Based on these analyses, a hybrid FPV approach is developed in which two flamelet libraries are constructed with conventional and modified progress variables, respectively. The results indicate that the hybrid FPV approach can predict both NO and other quantities of interest quite well at the same time under various operating conditions of strain rate, coal particle diameter, coal mass flow rate, and initial temperature.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Hybrid Flamelet/Progress Variable Approach for NO Prediction in Pulverized Coal Flames

et al. 2020

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“…Therefore this SGS model becomes case sensitive. Rieth et al 8 used Smagorinsky SGS model, whereas Adamczyk et al, Muto et al, 9,10 used Dynamic SGS model to model fine scales in LES turbulent model applied to PCC. Irrespective of the different approach used to model SGS, LES need a longer computational time with a multi-core parallel processing facility, which is mentioned by all the authors.…”

Section: Gas-phase Turbulent Modelsmentioning

confidence: 99%

Pulverized coal combustion computational modeling approach: A review

Ghose

Sahoo

Sahu

2022

Proceedings of the Institution of Mechanical Engineers, Part A:

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CFD (Computational fluid dynamics) is a tool, through which, the entire combustion process for pulverized coal combustion (PCC) can be predicted. The solid fuel combustion modeling is not as simple as gaseous or liquid fuel combustion modeling. In the solid fuel combustion process, various physical transformations and chemical reactions occur simultaneously. Therefore in the computational modeling approach for PCC, basic physical and chemical processes such as; turbulence, radiation, devolatilization, gas-phase combustion, char reaction and soot formation/reduction are integrated to obtain the desired results. However, in order to reach the desired accuracy, different computational models should be chosen carefully. In this review, various common models that are widely used in PCC simulation are discussed scientifically along with their modeling aspects. The basic advantages and disadvantages of these models are also discussed in this study. Moreover, different models preferred by various authors for pulverized coal combustion simulation process are also summarized. From the review, it has been observed that the eddy viscosity based two-equation turbulent models and Eulerian-Lagrangian multiphase approach are mostly preferred due to better computational economy. Two competing rate devolatilization model from various finite rate models and FG-DVC devolatilization model from various phenomenological models are mostly used for PCC. Diffusion kinetic control and Intrinsic char combustion models are mostly chosen to predict the char reaction. Finite reaction rate models are preferred when the computational economy is a concern, whereas phenomenological models provide results with better accuracy because in phenomenological models realistic inputs are given as input for simulation whereas, in finite rate models, finite rate constants are mostly empirical. Most of the gas phase models are given almost equal importance. Discrete ordinate (DO) is mostly used for PCC due to its ability of volumetric radiation calculation and the ability to evaluate radiation effect on the particle phase.

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“…Even though the calorific value of Coal C is higher than Coal B, the predicted temperature for Coal C is lower than the Coal B. Theoretically, coals with higher fixed carbon and calorific value might result in higher temperature during the combustion process [17]. However, other parameter such as fuel ratio could also play significant role in the combustion behaviour [18]. Fuel ratio is the ratio of fixed carbon to volatile matter.…”

Section: Flame Temperature Velocity O2 and Co Mass Fractionmentioning

confidence: 99%

CFD Analysis on the Effects of Different Coal on Combustion Characteristics in Coal-fired Boiler

Noor

Hasini

Samsuri

et al. 2020

CFDL

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Coal quality is essential for the optimum functioning of coal-fired power plants. One of the issues associated with coal quality deterioration is poor combustion behaviour which could result in ash deposition and environmental issues. This paper presents a CFD investigation of flow and combustion process in a full-scale furnace. Three different sub-bituminous coals with different properties were tested namely Coal A, B and C. The aim is to predict the combustion performance of these coals by observing its flow, temperature and species concentration inside the furnace. The exact boiler furnace geometry obtained from boiler operator was translated into CFD model with very little modification made for optimizing mesh. Grid dependency test carried out prior to the work shows the current mesh scheme is sufficient to accurately resolve the flow field. The results of the study show that combustion temperature for Coal B is the highest at approximately 1400°C. Coal C is predicted to give the highest velocity peak at certain regions of the furnace and interestingly enough, the same coal shows the shortest flame length and thus requiring additional flow to achieve the same penetration compared to other coals. Tracing of oxygen concentration inside the furnace show minimum oxygen left in the rear pass given by Coal A, indicating optimum combustion.

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Large eddy simulation of pulverized coal combustion in multi-burner system–effect of in-furnace blending method on NO emission

Cited by 23 publications

References 33 publications

Hybrid Flamelet/Progress Variable Approach for NO Prediction in Pulverized Coal Flames

Hybrid Flamelet/Progress Variable Approach for NO Prediction in Pulverized Coal Flames

Pulverized coal combustion computational modeling approach: A review

CFD Analysis on the Effects of Different Coal on Combustion Characteristics in Coal-fired Boiler

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