Gasification of woodchip particles: Experimental and numerical study of char–H2O, char–CO2, and char–O2 reactions

Steene, Laurent Van de; Tagutchou, Jean Philippe; Sanz, Francisco Javier Escudero; Salvador, Sylvain

doi:10.1016/j.ces.2011.05.045

Cited by 69 publications

(79 citation statements)

References 28 publications

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“…In a recent study [23,14], the authors demonstrated that the gasification rate was not influenced when varying the char particle size in the range of 10.5 15 mm. The influencing characteristic dimension was rather the particle thickness, as it slowed down the reaction rate by 1.6 times when it was increased from 1.5 to 6 mm for a constant size of 10.5 mm.…”

Section: Biomass Feedstock and Char Preparation 221 Biomass Feedstockmentioning

confidence: 99%

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The gasification reactivity of high-heating-rate chars in single and mixed atmospheres of H2O and CO2

Guizani

Sanz

Salvador

2013

Fuel

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145

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. The gasification reactivity of high-heating-rate chars in single and mixed atmospheres of H2O and CO2. Fuel, Elsevier, 2013, 108, pp.812-823. 10.1016/j.fuel.2013 The gasification reactivity of high-heating-rate chars in single and mixed atmospheres of H 2 O and CO 2 C. Guizani ⇑ , F.J. Escudero Sanz, S. Salvador t r a c tGasification reactivity of high heating rate chars (HHR chars) in steam, carbon dioxide and their mix tures was investigated in a new macro TG experimental device. The higher reactivity of the HHR chars was highlighted by a comparison with reference chars prepared at a low heating rate (LHR chars). It was found that the char reactivity in a mixed atmosphere of steam and carbon dioxide can be expressed as the sum of the individual reactivities obtained in single atmosphere gasification experiments. This result was not dependent on the pyrolysis heating rate. In addition, gas alternation gasification experi ments for both HHR chars and LHR chars showed that gasifying the char with CO 2 up to 30% of con version does not affect its reactivity to H 2 O. Altogether, the results tend to indicate that the two reactant gases H 2 O and CO 2 react on separate active sites when mixed atmospheres are used, and that CO 2 does not affect the char structure to favor or inhibit the char H 2 O gasification reaction.

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Section: Biomass Feedstock and Char Preparation 221 Biomass Feedstockmentioning

confidence: 99%

“…For instance, some authors referred to a (0.2 0.8) conversion range with a reference at X 0.2 [36], others chose ranges between (0.2 0.8) and (0.15 0.9) with a reference reactivity at X 0.5 [26,23]. In our study, FðXÞ is determined in the conver sion level range of 0.2 0.9.…”

Section: Fðxþmentioning

confidence: 99%

The gasification reactivity of high-heating-rate chars in single and mixed atmospheres of H2O and CO2

Guizani

Sanz

Salvador

2013

Fuel

Self Cite

145

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“…-development and calibration of a detailed particle model that enables the prediction of the particle conversion rate of a char particle under various gasification operating conditions [3,10]; -choice of a limited set of influencing parameters regarding gasification reactions; -determination of functions thanks to ''numerical'' experiments using the validated model.…”

Section: Methodsmentioning

confidence: 99%

“…In the present work, the only output of interest from the model is the global conversion of the char particle versus time: X(t). Accurate sensitivity of the calculated conversion to operating conditions and particle size was demonstrated by comparing simulations with experimental results [10].…”

Section: The Particle Modelmentioning

confidence: 99%

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Prediction of the gasification kinetics of a single wood char particle from a limited set of parameters

Teixeira¹,

Steene²,

Ponthieux³

et al. 2014

Fuel

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. Prediction of the gasification kinetics of a single wood char particle from a limited set of parameters. Fuel, Elsevier, 2014, 123, pp.194-204 Three functions were built to calculate particle conversion rate of steam gasification, Boudouard reaction and combustion. Function determination includes the use of a validated particle model and a numerical experimental design. The functions take into account all phenomena controlling particle conversion rate of a char particle under a reactive atmosphere.The functions depend on a limited set of operating conditions -T, p i -and particle properties: e 0 , e p,0 and A i .The functions can be easily adapted to a new wood char by confronting 3-5 experimental results to the function. Keywords:Gasification Particle conversion rate Char particle Modeling a b s t r a c t Many biomass gasification models have been developed at reactor scale with the objectives of understanding the phenomena involved and optimizing the processes. Most of usual models consist in solving equations of heat, mass and momentum balance in a multiphase media. These equations call for source terms that provide production or consumption of heat and species by the reactions. The heat and mass source terms are directly derived from the particle conversion rate, dX/dt. This paper focuses on the determination of these source terms regarding the char gasification stage of the gasification process.We propose three simple functions to calculate wood particle conversion rate of steam gasification, Boudouard reaction and combustion. The determination of each function is based on a validated char gasification model at particle size and a numerical experimental design. The model of char particle gasification includes all the complexity of the transformation: intrinsic reaction kinetic and both internal and external heat/mass transfer limitations. The experimental design was used to define simulations to be carried out, and to establish a relevant correlation between the particle conversion rate and a limiting set of 5 influencing parameters. Two of them are representative of the operating conditions -temperature and partial pressure of the reactant gas, the three others corresponds to particle properties: porosity, thickness, and reactivity constant.The three functions were determined for the gasification of a wood chips char particle in a H 2 O/N 2 , CO 2 / N 2 , and O 2 /N 2 atmosphere respectively. And finally, considering wood pellet char, we showed that the functions could be adapted to this new char from only 3 to 5 experiments, showing a good correspondence between prediction functions and experimental results.

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Simulation of biomass char gasification in a downdraft reactor for syngas production

et al. 2015

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A steady state, one-dimensional computational fluid dynamics model of wood char gasification in a downdraft reactor is presented. The model is not only based on reaction kinetics and fluid flow in the porous char bed but also on equations of heat and mass conservation. An original OpenFOAM solver is used to simulate the model and the results are found to be in good agreement with published experimental data. Next, a sensitivity analysis is performed to study the influence of reactor inlet temperature and gas composition on char conversion, bed temperature profile and syngas composition. In addition, the evolution of the complex reaction mechanisms involved in mixed atmosphere gasification is investigated, and the most suitable operating parameters for controlling syngas composition are evaluated. Our simulation results provide essential knowledge for optimizing the design and operation of downdraft gasifiers to produce syngas that meets the requirements of various biofuel applications.In all graphs, the experimental data provided by Teixeira et al. 24 are represented by triangles, and the predicted values from OPENFOAM and COMSOL 24 simulations are represented by solid and dashed lines, respectively. [Color figure can be viewed in the online issue, which is available at wileyonlinelibrary.com.]

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Gasification of woodchip particles: Experimental and numerical study of char–H2O, char–CO2, and char–O2 reactions

Cited by 69 publications

References 28 publications

The gasification reactivity of high-heating-rate chars in single and mixed atmospheres of H2O and CO2

The gasification reactivity of high-heating-rate chars in single and mixed atmospheres of H2O and CO2

Prediction of the gasification kinetics of a single wood char particle from a limited set of parameters

Simulation of biomass char gasification in a downdraft reactor for syngas production

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