A char combustion sub-model for CFD-predictions of fluidized bed combustion - experiments and mathematical modeling

Bibrzycki, J.; Mancini, Marco; Szlęk, Andrzej; Weber, Roman

doi:10.1016/j.combustflame.2015.09.024

Cited by 23 publications

(7 citation statements)

References 55 publications

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“…However, the size of the ash layer is increasing and the char core keeps shrinking. Hence, this process is similar to the ''shrinking particle model'' discussed in the study by Bibrzycki et al 18 On the surface of the firebrand, there are several possible heat transfer processes. As the oxidation reaction takes place on the surface, heat is being generated.…”

Section: Theoretical Backgroundsupporting

confidence: 52%

A computational fluid dynamics model to estimate local quantities in firebrand char oxidation

Banagiri,

Meadows,

Lattimer

2023

Journal of Fire Sciences

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Firebrand burning is a complex phenomenon that is influenced by several parameters which are difficult to fully explore experimentally. Computational fluid dynamics models capable of predicting local quantities are essential for accurate prediction of char oxidation in firebrands. This article presents a computational fluid dynamics model to estimate firebrand mass loss, diameter change, and surface temperature during char oxidation. The model was validated using previously conducted wind tunnel experiments. These experiments were conducted for firebrands of two different aspect ratios, which were arranged in three different configurations (single, horizontal array, and vertical array), and for four different wind speeds (0.5, 1, 1.5, and 2 m/s). The computational fluid dynamics results were compared with a previous 1 D model. In all the test cases, the computational fluid dynamics model predicted the physical phenomena with significantly improved accuracy compared to a 1 D model. The char oxidation model presented in this article can be coupled with other models to study firebrand generation and trajectory, biomass pyrolysis, fluidized bed reactors, and coal combustion.

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Section: Theoretical Backgroundsupporting

confidence: 52%

A computational fluid dynamics model to estimate local quantities in firebrand char oxidation

Banagiri,

Meadows,

Lattimer

2023

Journal of Fire Sciences

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“…The sensitivity n of the combustion rate to O 2 concentration is important in the simulation and prediction of char combustion; n is commonly taken to be 0–1. In the calculation of kinetic parameters, it is frequently assumed that n = 0.5 or n = 1. − The reported values of n vary widely and are contentious. One important reason is that it is difficult to measure heat and mass transfer.…”

Section: Resultsmentioning

confidence: 99%

Development of a Multistage in Situ Reaction Analyzer Based on a Micro Fluidized Bed and Its Suitability for Rapid Gas–Solid Reactions

et al. 2016

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An in situ decoupling analytical method was proposed and a multistage in situ reaction analyzer based on a micro fluidized bed (MFB-MIRA) was developed for in situ and on-line analysis of multistage gas−solid reaction processes. The responses of the pipe system to various gas concentration waves were analyzed. The in situ decoupled combustion properties of three coals were investigated using a two-stage reaction procedure involving devolatilization in Ar and combustion in O 2 /Ar. The Peclet number of the pipe flow was as large as 87, indicating approximate plug flow in the MFB-MIRA. A concentration correction model was built to simulate the real gas release process in the micro fluidized-bed reactor. The measurement distortions in the char combustion concentration curves were found negligible, which proved the reliability of using the measured results directly to derive the carbon conversion processes. The MFB-MIRA gives a good mass balance. The combustion reaction orders of the three in situ chars in O 2 were all about 0.9 during the main reaction period and decreased monotonously with increasing carbon conversion after the maximum rate. Calculations of heat and mass transfer during char combustion showed that isothermal reaction conditions were guaranteed and combustion during carbon conversions of 0.3−0.8 were kinetically controlled. This study proves that the MFB-MIRA is suitable for rapid gas−solid reactions.

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“…The oxygen transfer is much slower then the reaction; the reaction front is narrowed to the particle surface the random pore model (RPM) method developed by Bhatia and Perlmutter (1980). Several research groups have used this method successfully (Kreitzberg et al 2020;Bibrzycki et al 2016;Beckmann et al 2017). Several particle models cover the combustion of nonconventional chars.…”

Section: Oxygen Availabilitymentioning

confidence: 99%

Developing an all-round combustion kinetics model for nonspherical waste-derived solid fuels

Szűcs

Szentannai

2020

Chem. Pap.

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The utilization of challenging solid fuels in the energy industry (especially the ones derived from wastes) has a big priority nowadays, as it is a valid option to keep the recent EU directive related to the decrease of landfills. However, there are serious technical challenges, connecting to the lack of knowledge about the behavior of these fuels in the combustion chamber. This paper discusses the specific aspects of developing particle models concerning the combustion of these non-conventional fuels. A new modeling approach is presented, using which it is possible to develop an all-round particle model that includes every significant influencing process. Moreover, it does not have any restrictions regarding the shape, size and the origin of the particle. As an integral component of this model, the distinctive aspects of intrinsic reaction kinetics related to waste fuels are presented as well.

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A char combustion sub-model for CFD-predictions of fluidized bed combustion - experiments and mathematical modeling

Cited by 23 publications

References 55 publications

A computational fluid dynamics model to estimate local quantities in firebrand char oxidation

A computational fluid dynamics model to estimate local quantities in firebrand char oxidation

Development of a Multistage in Situ Reaction Analyzer Based on a Micro Fluidized Bed and Its Suitability for Rapid Gas–Solid Reactions

Developing an all-round combustion kinetics model for nonspherical waste-derived solid fuels

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