Thermal behavior of an engineered fuel and its constituents for a large range of heating rates with emphasis on heat transfer limitations

Vekemans, Odile; Laviolette, Jean‐Philippe; Chaouki, Jamal

doi:10.1016/j.tca.2014.12.007

Cited by 17 publications

(21 citation statements)

References 32 publications

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“…These newly found values are 19 to 21 % lower than those found from the literature from similar coals . The results can be explained by a gradient of temperature of 185 to 209 °C . More explanation is given in the Gasification section.…”

Section: Resultsmentioning

confidence: 93%

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Coal pyrolysis and gasification in a fluidized bed thermogravimetric analyzer

Samih

Chaouki

2018

Can J Chem Eng

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The kinetics and modelling of coal gasification were studied in the newly developed fluidized bed thermogravimetric analyzer. The total weight loss obtained from the fluidized bed reactor and the total gas product are in general agreement. The presented model for the micro‐fluidized bed reactor encompasses the kinetics of coal pyrolysis as well as the gasification reactions. For coal pyrolysis, the resulting activation energies for the individual gases were 34.7 to 59.8 kcal/mol. These values are 19 to 21 % lower than those found in the literature for similar coals. This decrease of the activation energies of the endothermic pyrolysis reactions is attributed to a gradient of temperature of 185 to 209 °C. The obtained activation energy for the CO shift reaction is 46.6 kcal/mol, increasing by 20 % from the one used in the literature. This increase of the activation energy of such a mildly exothermic reaction represents an equivalent of 170 °C gradient of temperature. The effects of temperature on the yield and the composition of the gas product are studied. Experimental results and equilibrium data are also compared. The model shows reasonably good agreement with the experimental results, except for the water gas shift reaction.

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Section: Resultsmentioning

confidence: 93%

“…The result is extremely interesting and is attributed to a measurement error of the local temperature in the past studies. In fact, the 20 % increase of the activation energy is the equivalent of a temperature gradient of 170 °C of such moderately exothermic reaction …”

Section: Resultsmentioning

confidence: 99%

Coal pyrolysis and gasification in a fluidized bed thermogravimetric analyzer

Samih

Chaouki

2018

Can J Chem Eng

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“…Limitations of conventional TGAs are related to sample size and heat and mass transfer rates. In samples with larger sizes, (<50 mg), heating rates within the sample are not rapid enough to ensure isothermal conditions, and poor mass transfer creates radial and axial concentration gradients . These limitations add uncertainty to kinetic parameters derived from conventional thermogravimetric analyzers (TGA) …”

Section: Uncertaintymentioning

confidence: 99%

“…The model assumed convection between the thermocouple and the sample holder was negligible and the gas volume produced during the degradation was inconsequential compared to the inlet gas flow. Further, it ignored radiation and included only conduction and convection from the gas stream (Equation ):

F_{gas} C_{normalp, gas} ((), T_{in} - T_{out}) + italicUS ((), T_{F} - T_{S}) = {mC}_{normalp, sample} \frac{normald T_{s}}{normald t} - normalΔ H_{rxn} \frac{normald m}{normald t} .

…”

Section: Uncertaintymentioning

confidence: 99%

Experimental methods in chemical engineering: Thermogravimetric analysis—TGA

et al. 2019

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Thermogravimetric analysis (TGA) is a quantitative analytical technique that monitors the mass of a sample from 1 mg to several g as a furnace ramps temperature to as high as 1600°C under a stable or changing gas flow. The first gravimetric test was in 27 BC when Vitruvius measured limestone's change of mass as it calcined to lime. In modern chemical engineering, researchers apply the technique to derive conversions, kinetics, and mechanisms for any process with a change of mass by isothermal, non‐isothermal, and quasi‐isothermal methods. The mass drops as the sample decomposes, volatile compounds evaporate, or the oxidation state decreases, while in reactive environments (with O2, for example), the mass of transition metals may increase. TGA is incapable of detecting phase transitions, polymorphic transformations, or reactions for which mass is invariant. DSC or DTA couple with TGA to help deconvolute a DSC plot by separating physical changes from chemical changes. Evolved gas analysis techniques monitor the gaseous products exiting the TGA furnace on‐line as the temperature ramps. A bibliometric map of keywords from articles citing TGA indexed by Web of Science in 2016 and 2017 identified five research clusters: nanoparticles, performance, and films; crystal structures, acid, and oxidation; composites, nanocomposites, and mechanical properties; kinetics, pyrolysis, and temperature; and adsorption, water and wastewater, and aqueous solutions. This review provides an overview of the basic principles of modern TGA.

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“…The waste fraction is made of 80% waste fibers (paper, cardboard, wood and some textiles), 10% waste hard plastics (HDPE (high-density polyethylene), PS (polystyrene) and PVC (polyvinyl chloride)) and 10% waste soft plastics (LDPE (low-density polyethylene) and LDPP (low-density polypropylene)). The ReEF™ without sorbent consists of a mixture of particles of fiber and plastics, which decompose independently [26]. SEM-EDS analysis of different ReEF™ samples was made.…”

Section: Methodsmentioning

confidence: 99%