Kinetic study of biomass char combustion in a low temperature fluidized bed reactor

Morin, Mathieu; Pécate, Sébastien; Hémati, Mehrdji

doi:10.1016/j.cej.2017.08.063

Cited by 50 publications

(25 citation statements)

References 45 publications

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“…As a general rule, polymers with an aliphatic backbone, like PLA, tend to generate less smoke during combustion than polyenic polymers and those with pendant aromatic groups, such as polystyrene, which produce more smoke [ 49 ]. Organic materials produce toxic carbon monoxide (CO) when not completely combusted, and in the later stages of combustion CO is oxidized to CO 2 [ 50 ]. From Table 6 , the addition of BP significantly increased the amounts of CO and CO 2 released from the material, whereas its substitution with BC had very mixed results for CO and CO 2 release.…”

Section: Resultsmentioning

confidence: 99%

Development of Biodegradable Flame-Retardant Bamboo Charcoal Composites, Part I: Thermal and Elemental Analyses

et al. 2020

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In this study, bamboo charcoal (BC) was used as a substitute filler for bamboo powder (BP) in a lignocellulose-plastic composite made from polylactic acid (PLA), with aluminum hypophosphite (AHP) added as a fire retardant. A set of BC/PLA/AHP composites were successfully prepared and tested for flame-retardancy properties. Objectives were to (a) assess compatibility and dispersibility of BC and AHP fillers in PLA matrix, and (b) improve flame-retardant properties of PLA composite. BC reduced flexural properties while co-addition of AHP enhanced bonding between PLA and BC, improving strength and ductility properties. Adding AHP drastically reduced the heat release rate and total heat release of the composites by 72.2% compared with pure PLA. The formation of carbonized surface layers in the BC/PLA/AHP composites effectively improved the fire performance index (FPI) and reduced the fire growth index (FGI). Flame-retardant performance was significantly improved with limiting oxygen index (LOI) of BC/PLA/AHP composite increased to 31 vol%, providing a V-0 rating in UL-94 vertical flame test. Adding AHP promoted earlier initial thermal degradation of the surface of BC/PLA/AHP composites with a carbon residue rate up to 40.3%, providing a protective layer of char. Further raw material and char residue analysis are presented in Part II of this series.

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Section: Resultsmentioning

confidence: 99%

Development of Biodegradable Flame-Retardant Bamboo Charcoal Composites, Part I: Thermal and Elemental Analyses

et al. 2020

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“…During combustion of organic materials, CO and CO 2 are primary products of the carbon–oxygen reaction. CO is generated first, which reacts with O 2 to form CO 2 [ 29 ]. A study by Du et al, (1991) [ 30 ] demonstrated how the presence of Ca in char particles strongly favours the formation of CO 2 as the substrate combusts; at 390 °C, the Ca content in char particles reduced the CO/CO 2 product ratio from 0.53 to 0.007.…”

Section: Resultsmentioning

confidence: 99%

Development of Biodegradable Flame-Retardant Bamboo Charcoal Composites, Part II: Thermal Degradation, Gas Phase, and Elemental Analyses

et al. 2020

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Bamboo charcoal (BC) and aluminum hypophosphite (AHP) singly and in combination were investigated as flame-retardant fillers for polylactic acid (PLA). A set of BC/PLA/AHP composites were prepared by melt-blending and tested for thermal and flame-retardancy properties in Part I. Here, in Part II, the results for differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), Fourier transform infrared (FTIR), thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR), X-ray diffraction (XRD), and X-ray photoelectron analysis (XPS) are presented. The fillers either singly or together promoted earlier initial thermal degradation of the surface of BC/PLA/AHP composites, with a carbon residue rate up to 40.3%, providing a protective layer of char. Additionally, BC promotes heterogeneous nucleation of PLA, while AHP improves the mechanical properties and machinability. Gaseous combustion products CO, aromatic compounds, and carbonyl groups were significantly suppressed in only the BC-PLA composite, but not pure PLA or the BC/PLA/AHP system. The flame-retardant effects of AHP and BC-AHP co-addition combine effective gas-phase and condensed-phase surface phenomena that provide a heat and oxygen barrier, protecting the inner matrix. While it generated much CO2 and smoke during combustion, it is not yet clear whether BC addition on its own contributes any significant gas phase protection for PLA.

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“…The ring system and random bonding reduce the density of charcoal to 1.0 g/cm 3 , which is significantly lower than that of single-crystal graphite (2.267 g/cm 3 ). The spaces between these bonded LCMs constitute the microporous structures of the charcoal, and during pyrolysis and carbonization, mesopores and macropores develop within the char matrix due to shrinkage [7].…”

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confidence: 80%

“…At low and high temperatures, oxygen almost completely penetrates the charcoal particle before the onset of significant oxidation. At temperatures < 900 K, the specific surface area of char changes as predicted by random pore models [3]. The reactivity of char under both oxidizing and inert conditions has been studied by thermogravimetric analysis [4,5].…”

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confidence: 99%

Reactivity and Free Radical Chemistry of Lilac (Syringa vulgaris) Charcoal

2019

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HIGHLIGHTSo Lilac ignites quickly (250-290 o C), and has a narrow combustion temperature range (300-o It is microporous with a surface area of 4.3706m 2 /g, o Lilac has C-C free radicals arising from carbonization, o It forms peroxyl radicals on oxidation in air, o Degassing in N2 and acid washing removes the free radicals. ABSTRACTThe reactivity, porosity and surface chemistry of charcoal determine its combustion behaviour, and these properties depend on the source of the original wood, production conditions and treatment. Here we studied the properties of charcoal derived from lilac (Syringa vulgaris). Its reactivity was tested by isothermal and non-isothermal thermogravimetric analysis and differential scanning calorimetry in air and nitrogen. Its porosity was tested by monitoring nitrogen adsorption at 77 K. The free radical concentration was determined by measuring the electron spin resonance of fresh charcoal, after washing with HCl, and after degassing in air with or without nitrogen. We found that lilac has a specific surface area of 4.3706 m 2 /g and is highly reactive, igniting at 250-300°C with peak combustion at 320-520°C. The quantity of oxygen consumed and heat released during oxidation increased with temperature. The free radical concentration in the fresh charcoal was 5.29 x 10 18 spins/g, compared to 3.49 x 10 19 spins/g after acid washing, 7.06 x 10 19 spins/g after exposure to air, and 3.75 x 10 17 spins/g after degassing with nitrogen before exposure to air. The line width of all the charcoal samples was 11.6-11.9 G. However, degassing the charcoal in nitrogen followed by exposure to air at low temperatures resulted in a four-fold increase in the line width to 41.8 G. The exposure of lilac charcoal to air alone at low temperatures resulted in the formation of persistent peroxyl radicals superimposed on the main peak. The g-values of charcoal samples that were fresh, acid washed, degassed in N2 + air, and degassed in air alone (main peak) were 2.00481, 2.00477, 2.00260 and 2.00483, respectively. The corresponding g-values of the peroxyl radicals superimposed on the main peak were 2.0155, 2.0138, 2.0020 and 2.0007, respectively. The reactivity, free radical content and specific surface area suggest that lilac charcoal is particularly suitable for applications involving energetic materials, catalysis and co-firing.

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Kinetic study of biomass char combustion in a low temperature fluidized bed reactor

Cited by 50 publications

References 45 publications

Development of Biodegradable Flame-Retardant Bamboo Charcoal Composites, Part I: Thermal and Elemental Analyses

Development of Biodegradable Flame-Retardant Bamboo Charcoal Composites, Part I: Thermal and Elemental Analyses

Development of Biodegradable Flame-Retardant Bamboo Charcoal Composites, Part II: Thermal Degradation, Gas Phase, and Elemental Analyses

Reactivity and Free Radical Chemistry of Lilac (Syringa vulgaris) Charcoal

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