A predictive multi-step kinetic model of coal devolatilization

Sommariva, Samuele; Maffei, Tiziano; Migliavacca, G.; Faravelli, Tiziano; Ranzi, E.

doi:10.1016/j.fuel.2009.07.023

Cited by 114 publications

(69 citation statements)

References 30 publications

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“…Pyrolytic conversion rates against temperature of the samples are presented in Figures –, and the optimized kinetic parameters are summarized in Table . Previously, two parallel decomposition reactions of coal are proposed by Kobayashi et al, and more complex multi‐step reaction schemes have been also proposed . From this work, the coal pyrolysis process can be predicted by three‐step reaction model as shown in Figure .…”

Section: Resultsmentioning

confidence: 93%

“…The rate equation can be expressed by the Arrhenius equation as:

\frac{d α}{d t} = A e x p true(- \frac{E}{R T} true) {true(1 - α true)}^{n}

where

E

is the activation energy;

R

is the universal gas constant of 8.314 Jmol · K; and

T

is the absolute temperature. However, since the thermal decomposition of solid fuel involves numerous reactions in parallel and in series over the process, multi‐step kinetic models have been proposed to evaluate the pyrolysis behaviour of coal and oil shale in literature, and so the other approach is carried out by a simplified multi‐step model assuming a number of paralleled n th ‐order reactions. The number of steps referring to the amount of kinetic pathways can be typically postulated to be two or three, while a larger number of steps has a risk of overfitting regardless of longer computation times .…”

Section: Methodsmentioning

confidence: 99%

“…Previously, two parallel decomposition reactions of coal are proposed by Kobayashi et al, [14] and more complex multi-step reaction schemes have been also proposed. [15] From this work, the coal pyrolysis process can be predicted by three-step reaction model as shown in Figure 4. The global reaction order of coal pyrolysis is determined to be higher than unity, and such a high value is a measure of complexity and multiplicity of the reaction mechanism.…”

Section: Kinetic Analysismentioning

confidence: 99%

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Pyrolysis and char oxidation characteristics of oil shales and coal in a thermogravimetric analyzer

Park

Song

2017

Can J Chem Eng

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Non‐isothermal thermogravimetric analysis was carried out on two different oil shales and sub‐bituminous coal in order to evaluate effects of the fuel properties and compare the reaction characteristics. The samples and their chars after the devolatilization were heated up to 900 °C at a constant heating rate of 10 K/min under inert and oxidizing atmospheres, respectively. Experimental results exhibit distinct behaviour between the samples for both pyrolysis and char oxidation processes. Pyrolysis of oil shale occurs in two temperature regimes corresponding to its organic and mineral degradation, and mineral matter plays important roles in production of the residual char at the second pyrolysis stage and its reactivity to the subsequent char oxidation. Kinetic analysis was performed using the global one‐ and multi‐step models with nth order reaction mechanism. Organic devolatilization processes of coal and oil shale are analyzed by three‐ and two‐step models, respectively, however mineral degradation of oil shale and char oxidation are analyzed by a one‐step model. Finally, a reasonable fit to the experimental data can be achieved for all the samples and their chars at different atmospheres.

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Section: Resultsmentioning

confidence: 93%

“…The rate equation can be expressed by the Arrhenius equation as:

\frac{d α}{d t} = A e x p true(- \frac{E}{R T} true) {true(1 - α true)}^{n}

where

E

is the activation energy;

R

is the universal gas constant of 8.314 Jmol · K; and

T

Section: Methodsmentioning

confidence: 99%

Section: Kinetic Analysismentioning

confidence: 99%

See 1 more Smart Citation

Pyrolysis and char oxidation characteristics of oil shales and coal in a thermogravimetric analyzer

Park

Song

2017

Can J Chem Eng

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“…The actual agent (gas) among those previously listed which was responsible for the phenomena of textural changes was not clear, although it was likely the same as the gas that coal itself produced during thermal treatment. If so, then ethylene should be considered as a possible gas that affected texture adjustments because it was a common phase formed during thermal transformations in coals [20]. However, this assumption should be verified by coke-making experiments in a gas-controlled environment.…”

Section: Interpretation Of the Resultsmentioning

confidence: 99%

Textural changes in metallurgical coke prepared with polyethylene

Gornostayev

Heino

Kokkonen

et al. 2014

Int J Miner Metall Mater

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The effect of high-density polyethylene (HDPE) on the textural features of experimental coke was investigated using polarized-light optical microscopy and wavelet-based image analysis. Metallurgical coke samples were prepared in a laboratory-scale furnace with 2.5%, 5.0%, 7.5%, 10.0%, and 12.5% HDPE by mass, and one sample was prepared by 100% coal. The amounts and distribution of textures (isotropic, mosaic and banded) and pores were obtained. The calculations reveal that the addition of HDPE results in a decrease of mosaic texture and an increase of isotropic texture. Ethylene formed from the decomposition of HDPE is considered as a probable reason for the texture modifications. The approach used in this study can be applied to indirect evaluation for the reactivity and strength of coke.

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“…Network pyrolysis models modelled the coal chemical structure as a macromolecular network in FG-DVC (group-depolymerization, vaporization and cross-linking) [3,12], FLASHCHAIN (distributed-energy chain) [13][14][15][16] and CPD (chemical percolation model for devolatilization) [17][18][19]. Recently Sommariva et al [20,21] presented a multi-step kinetic chemical mechanism by describing coals in three reference configurations. Although many researchers have done excellent work in modelling pyrolysis chemical changes, some phenomena are still not explained, such as the high volatile releases at high temperatures and how coals with similar initial chemical compositions have different final yields in the same pyrolysis environment.…”

Section: Introductionmentioning

confidence: 99%

Fragmentation and diffusion model for coal pyrolysis

Chen

2011

Journal of Analytical and Applied Pyrolysis

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A predictive multi-step kinetic model of coal devolatilization

Cited by 114 publications

References 30 publications

Pyrolysis and char oxidation characteristics of oil shales and coal in a thermogravimetric analyzer

Pyrolysis and char oxidation characteristics of oil shales and coal in a thermogravimetric analyzer

Textural changes in metallurgical coke prepared with polyethylene

Fragmentation and diffusion model for coal pyrolysis

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