Comparison of different global reaction mechanisms for coal-fired utility boilers

Rückert, Frank U.; Sabel, Thomas; Schnell, Uwe; Hein, K. R. G.; Risio, Benedetto

doi:10.1504/pcfd.2003.003773

Cited by 11 publications

(3 citation statements)

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“…The reaction rates of each species are calculated on a mass balance for the fine-structure reactor. Denoting quantities of fine structures with asterisk, the i species conservation equation can be expressed as follows [46]:…”

Section: Models For Reactive Flow Simulations Of Chemical Reactions A...mentioning

confidence: 99%

Impact of Chemistry–Turbulence Interaction Modeling Approach on the CFD Simulations of Entrained Flow Coal Gasification

Mularski

Modliński

2020

Energies

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This paper examines the impact of different chemistry–turbulence interaction approaches on the accuracy of simulations of coal gasification in entrained flow reactors. Infinitely fast chemistry is compared with the eddy dissipation concept considering the influence of turbulence on chemical reactions. Additionally, ideal plug flow reactor study and perfectly stirred reactor study are carried out to estimate the accuracy of chosen simplified chemical kinetic schemes in comparison with two detailed mechanisms. The most accurate global approach and the detailed one are further implemented in the computational fluid dynamics (CFD) code. Special attention is paid to the water–gas shift reaction, which is found to have the key impact on the final gas composition. Three different reactors are examined: a pilot-scale Mitsubishi Heavy Industries reactor, a laboratory-scale reactor at Brigham Young University and a Conoco-Philips E-gas reactor. The aim of this research was to assess the impact of gas phase reaction model accuracy on simulations of the entrained flow gasification process. The investigation covers the following issues: impact of the choice of gas phase kinetic reactions mechanism as well as influence of the turbulence–chemistry interaction model. The advanced turbulence–chemistry models with the complex kinetic mechanisms showed the best agreement with the experimental data.

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Section: Models For Reactive Flow Simulations Of Chemical Reactions A...mentioning

confidence: 99%

Impact of Chemistry–Turbulence Interaction Modeling Approach on the CFD Simulations of Entrained Flow Coal Gasification

Mularski

Modliński

2020

Energies

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“…Pulverized fuel combustion has been investigated by many researchers over several decades [10][11][12][13][14][15][16][17][18][19][20][21][22]. Comprehensive overviews on simulation procedures for the combustion of pulverized coal are provided in Epple et al [23] and Hasse et al [24].…”

Section: Introductionmentioning

confidence: 99%

A Validation Study for RANS Based Modelling of Swirling Pulverized Fuel Flames

2021

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A swirling pulverized coal flame is computationally investigated. A Eulerian–Lagrangian formulation is used to describe the two-phase flow. Turbulence is modelled within a RANS (Reynolds averaged numerical simulation) framework. Four turbulence viscosity- (TV) based models, namely the standard k-ε model, realizable k-ε model, renormalization group theory k-ε model, and the shear stress transport k-ω model are used. In addition, a Reynolds stress transport model (RSM) is employed. The models are assessed by comparing the predicted velocity fields with the measurements of other authors. In terms of overall average values, the agreement of the predictions to the measurements is observed to be within the range 20–40%. A better performance of the RSM compared to the TV models is observed, with a nearly twice as better overall agreement to the experiments, particularly for the swirl velocity. In the second part of the investigation, the resolution of the discrete particle phase in modelling the turbulent particle dispersion (TPD) and particle size distribution (SD) is investigated. Using the discrete random walk model for the TPD, it is shown that even five random walks are sufficient for an accuracy that is quite high, with a less than 1% mean deviation from the solution obtained by thirty random walks. The approximation of the measured SD is determined by a continuous Rosin–Rammler distribution function, and inaccuracies that can occur in its subsequent discretization are demonstrated and discussed. An investigation on the resolution of the SD by discrete particle size classes (SC) indicates that 12 SC are required for an accuracy with a less than 1% mean deviation from the solution with 18 SC. Although these numbers may not necessarily be claimed to be sufficiently universal, they may serve as guidance, at least for SD with similar characteristics.

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“…The main combustion parameters used for these improvements were equivalence ratio and the reactants input conditions . Many researchers have developed these global mechanisms exclusively for a certain application or to predict certain combustion properties, e.g., the laminar flame speed, the ignition delay time, , CO concentration and the heat release or the flame temperature, − and NO and CO pollutants concentration. , …”

Section: Introductionmentioning

confidence: 99%

Integrated Procedure, Using Differential Evolution Optimization of Rate Parameters, for Design of Small and Accurate Multistep Global Chemical Mechanisms

Shakeri

Mazaheri

2018

Ind. Eng. Chem. Res.

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Three-dimensional analysis of combustion chambers in industrial gas turbines suffers from lack of simple and accurate reduced mechanisms for oxidation of hydrocarbon fuels. Here, an integrated procedure is introduced based on a differential evolution optimization technique. The procedure is flexible and modular and allows optimization of many rate parameters of a multistep global mechanism based on many different combustion criteria and inlet or operational conditions. The procedure uses any selected chemical reactor model and any reference combustion mechanism provided. Sample design criteria used here are flame temperature, ignition delay time, and concentration of selected species, especially pollutants. Different low atmospheric pressures and high pressure combustion conditions are considered. Reactor models used here are zero and one-dimensional reactors of PSR, PFR, IGNITION, and PREMIX models. To show applicability and performance of the procedure, the algorithm is analyzed in detail during four different case studies. The first two cases consider application to methane, using a five-step global mechanism. Case 3 considers application of a 3-sep mechanism for simulation of propane oxidation, and finally kerosene oxidation via a 3-step mechanism to predict its transient behavior is studied in case 4. Many global, temporal and spatial combustion properties are studied, and it is shown that for most off-design conditions studied here, the relative error of the most significant performance parameters is below one percent.

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Comparison of different global reaction mechanisms for coal-fired utility boilers

Cited by 11 publications

References 0 publications

Impact of Chemistry–Turbulence Interaction Modeling Approach on the CFD Simulations of Entrained Flow Coal Gasification

Impact of Chemistry–Turbulence Interaction Modeling Approach on the CFD Simulations of Entrained Flow Coal Gasification

A Validation Study for RANS Based Modelling of Swirling Pulverized Fuel Flames

Integrated Procedure, Using Differential Evolution Optimization of Rate Parameters, for Design of Small and Accurate Multistep Global Chemical Mechanisms

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