Global Kinetic Modeling of Coal Devolatilization in a Thermogravimetric Balance and Drop-Tube Furnace

Authier, Olivier; Thunin, Emmanuel; Plion, P.; Porcheron, Lynda

doi:10.1021/ef502600t

Cited by 16 publications

(27 citation statements)

References 24 publications

(73 reference statements)

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“…Validation of reduced models relies on experimental data. For coal combustion the most common experiments have historically been thermogravimetric analysis (TGA) and drop tube reactor (DTR) experiments [26][27][28], although recently the entrained flow reactors (EFR) are emerging as a more viable tool for derivation, validation and uncertainty quantification of models in conditions similar to those of industrial-scale facilities [29][30][31]. The experimental data used in this work are the results of devolatilization tests carried out in the same experimental apparatus, the Isothermal Plug Flow Reactor (IPFR), at 1173, 1373 and 1573 K, and performed on the Sebuku bituminous coal.…”

Section: Experimental Datamentioning

confidence: 99%

Collaborative simulations and experiments for a novel yield model of coal devolatilization in oxy-coal combustion conditions

Iavarone

Smith

et al. 2017

Fuel Processing Technology

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Oxy-coal combustion is an emerging low-cost "clean coal" technology for emissions reduction and Carbon Capture and Sequestration (CCS). The use of Computational Fluid Dynamics (CFD) tools is crucial for the development of cost-effective oxy-fuel technologies and the minimization of environmental concerns at industrial scale. The coupling of detailed chemistry models and CFD simulations is still challenging, especially for large-scale plants, because of the high computational efforts required. The development of scale-bridging models is therefore necessary, to find a good compromise between computational efforts and the physical-chemical modeling precision. This work presents a procedure for scale-bridging modeling of coal devolatilization, in the presence of experimental error, that puts emphasis on the thermodynamic aspect of devolatilization, namely the final volatile yield of coal, rather than kinetics. The procedure consists of an engineering approach based on dataset consistency and Bayesian methodology including Gaussian-Process Regression (GPR). Experimental data from devolatilization tests carried out in an oxy-coal entrained flow reactor were considered and CFD simulations of the reactor were performed. Jointly evaluating data and simulations, a novel yield model was validated against the data via consistency analysis. In parallel, a Gaussian-Process Regression was performed, to improve the understanding of the uncertainty associated to the devolatilization, based on the experimental measurements. Potential model forms that could predict yield during devolatilization were obtained. The set of model forms obtained via GPR includes the yield model that was proven to be consistent with the data. The overall procedure has resulted in a novel yield model for coal devolatilization and in a valuable evaluation of uncertainty in the data, in the model form, and in the model parameters.

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Section: Experimental Datamentioning

confidence: 99%

Collaborative simulations and experiments for a novel yield model of coal devolatilization in oxy-coal combustion conditions

Iavarone

Smith

et al. 2017

Fuel Processing Technology

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“…Although this technique allows obtaining accurate mass loss curves with a high time resolution, only low heating rates (typically less than 50 K min –1 ) can be set, which is significantly different from the conditions involved in industrial combustors. To tackle this issue, more realistic experimental devices, including flat flame reactors (FFR) − and drop tube furnaces (DTF), ,,, are also used. Fast heating rates between 10 4 and 10 6 K s –1 can then be reached, which allows the assessment of kinetic parameters that are more relevant for industrial applications.…”

Section: Introductionmentioning

confidence: 99%

Kinetic Modeling of the Devolatilization of Pulverized Coal, Poplar Wood, and Their Blends in a Thermogravimetric Analyzer and a Flat Flame Reactor

Lemaire,

Wang,

Menanteau

2023

ACS Omega

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Devolatilization kinetics of coal, poplar wood, and blends containing 10 and 20 wt % of biomass were characterized. Measurements were carried out under inert atmosphere with heating rates between 10 K min–1 and ∼106 K s–1 using a thermogravimetric analyzer (TGA) and a flat flame reactor (FFR). Measured data were simulated using the chemical percolation devolatilization (CPD) model and a global kinetic scheme based on two competitive reactions integrating a refined differential reaction model. The CPD model failed to simulate TGA results but reproduced FFR data relatively well. As for the global model, selecting kinetic parameters from the literature turned out to lead to unsuitable predictions. Fitted values of the activation energies E a,i , pre-exponential factors A i , mass stoichiometric coefficients Y i , and the reaction model factor n were therefore inferred using a genetic algorithm-based optimization procedure, leading to obtain an excellent agreement between simulated and measured data. The assessed E a,i values were found to be lower for wood than for coal, which is consistent with the higher energy required to break the strong C–C bonds holding the highly cross-linked aromatic structures of coal. Besides, blending coal with 20 wt % of wood induced a decrease of E a,i values, which went from 99.79 to 86.1 kJ mol–1 and from 186.72 to 171.57 kJ mol–1 for the first and second reactions prevailing at low and high temperatures, respectively. Finally, the fact that the activation energy of the first devolatilization reaction was found to be lower with the blend containing 20% of wood than for wood illustrated the probable existence of synergies, as also exemplified by the characteristic devolatilization times for blended samples, which were found to be relatively similar to and even lower than that of wood.

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“…For coal devolatilization, a variety of models were developed to define the rate of the process and the amount of volatile matter released. These models were validated on experimental data usually taken from thermogravimetric analysis (TGA) and drop tube reactor (DTR) experiments [4][5][6], although the entrained flow reactors (EFRs) are recently emerging as the most viable way for validation of solid fuel behavior at temperatures and heating rates typical of industrial combustion devices. Indeed, EFRs could provide the most valuable validation dataset for predicting the ignition behavior of coal and the heating rate influence on coal devolatilization in industrial boilers [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

CFD-aided benchmark assessment of coal devolatilization one-step models in oxy-coal combustion conditions

Iavarone

Galletti

Contino

et al. 2016

Fuel Processing Technology

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Coal devolatilization, as first step in thermochemical processes involving solid fuels, has been targeted in plenty of CFD investigations: despite the variety of models that were developed to define the rate of the process and the amount of volatile matter released, not all of them are suitable for CFD simulations of large-scale coal combustors. Empirical models ensure both simplicity and feasibility, but not full reliability for all coal types and operating conditions. CFD modeling results for coal conversion during devolatilization in an entrained flow reactor and oxy-conditions are presented and compared to experimental data. A benchmark assessment of one-step models on the accuracy of the volatile yield prediction is then performed. It is shown that the heating rate strongly influences the devolatilization process and its modeling, not only in terms of rate but also in terms of yield, which differs significantly from the proximate analysis value. This indicates the need for a model able to predict the variation of coal volatile yield with temperature and heating rate, in addition to the kinetic model

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Global Kinetic Modeling of Coal Devolatilization in a Thermogravimetric Balance and Drop-Tube Furnace

Cited by 16 publications

References 24 publications

Collaborative simulations and experiments for a novel yield model of coal devolatilization in oxy-coal combustion conditions

Collaborative simulations and experiments for a novel yield model of coal devolatilization in oxy-coal combustion conditions

Kinetic Modeling of the Devolatilization of Pulverized Coal, Poplar Wood, and Their Blends in a Thermogravimetric Analyzer and a Flat Flame Reactor

CFD-aided benchmark assessment of coal devolatilization one-step models in oxy-coal combustion conditions

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