On the Experimental Evidence of Exothermicity in Wood and Biomass Pyrolysis

Blasi, Colomba Di; Branca, Carmen; Galgano, Antonio

doi:10.1002/ente.201600091

Cited by 43 publications

(30 citation statements)

References 74 publications

(157 reference statements)

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“…The exothermic effect of BSG pyrolysis was also observed by Ferraz et al [64]. Subject literature reports that pyrolysis at a small scale (mg) is endothermic [65][66][67][68]; however, the exothermic effect of biomass pyrolysis is also reported [69][70][71]. The final thermal effect of thermal degradation strongly depends on the composition of the investigated material.…”

Section: Heat Flow During Pyrolysis Reactionsupporting

confidence: 58%

Pyrolysis Kinetics of Hydrochars Produced from Brewer’s Spent Grains

et al. 2019

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The current market situation shows that large quantities of the brewer’s spent grains (BSG)—the leftovers from the beer productions—are not fully utilized as cattle feed. The untapped BSG is a promising feedstock for cheap and environmentally friendly production of carbonaceous materials in thermochemical processes like hydrothermal carbonization (HTC) or pyrolysis. The use of a singular process results in the production of inappropriate material (HTC) or insufficient economic feasibility (pyrolysis), which hinders their application on a larger scale. The coupling of both processes can create synergies and allow the mentioned obstacles to be overcome. To investigate the possibility of coupling both processes, we analyzed the thermal degradation of raw BSG and BSG-derived hydrochars and assessed the solid material yield from the singular as well as the coupled processes. This publication reports the non-isothermal kinetic parameters of pyrolytic degradation of BSG and derived hydrochars produced in three different conditions (temperature-retention time). It also contains a summary of their pyrolytic char yield at four different temperatures. The obtained KAS (Kissinger–Akahira–Sunose) average activation energy was 285, 147, 170, and 188 kJ mol−1 for BSG, HTC-180-4, HTC-220-2, and HTC-220-4, respectively. The pyrochar yield for all hydrochar cases was significantly higher than for BSG, and it increased with the severity of the HTC’s conditions. The results reveal synergies resulting from coupling both processes, both in the yield and the reduction of the thermal load of the conversion process. According to these promising results, the coupling of both conversion processes can be beneficial. Nevertheless, drying and overall energy efficiency, as well as larger scale assessment, still need to be conducted to fully confirm the concept.

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Section: Heat Flow During Pyrolysis Reactionsupporting

confidence: 58%

Pyrolysis Kinetics of Hydrochars Produced from Brewer’s Spent Grains

et al. 2019

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“…Recent work explains that exothermicity is linked to the heterogeneous secondary reactions of volatile species. This is in agreement with the results presented by Di Blasi et al [19]; the lowly porous structure of the particle may impact on the secondary reactions of the process. Thus, in a biomass matrix structure (with low porosity), the retention time of the produced gases during torrefaction is higher, which could contribute to increasing the charring reactions (and the associated exothermicity) [19].…”

Section: Torrefaction At Laboratory Scalesupporting

confidence: 94%

“…This is in agreement with the results presented by Di Blasi et al [19]; the lowly porous structure of the particle may impact on the secondary reactions of the process. Thus, in a biomass matrix structure (with low porosity), the retention time of the produced gases during torrefaction is higher, which could contribute to increasing the charring reactions (and the associated exothermicity) [19]. Interestingly, the peak at 350 • C is higher than that obtained at 300 • C. The results indicate that the peaks' height can be associated with the amount of produced volatile species (obviously, at 350 • C, the cellulose is more degraded than at 300 • C).…”

Section: Torrefaction At Laboratory Scalesupporting

confidence: 94%

Upscaling Severe Torrefaction of Agricultural Residues to Produce Sustainable Reducing Agents for Non-Ferrous Metallurgy

Demey

Rodriguez-Alonso

Lacombe

et al. 2021

Metals

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Torrefaction of almond shells and olive stones, which are typically considered agricultural waste in the southern regions of the European Union, was investigated in this work for application as reducing agents in the metallurgical industry. Four different temperatures were tested: 250, 280, 300 and 350 °C. The evolution of the solid yields with the temperature was determined with TGA measurements. This showed that the duration of torrefaction should not exceed 45 min. The kinetic profiles were successfully fitted using the pseudo-first-order rate equation (PFORE). Then, torrefaction for 45 min was systematically carried out at every temperature and for each resource in a laboratory-scale batch device. The raw and torrefied biomasses were characterized using proximate, ultimate and calorific analyses. The carbon/oxygen ratio and the heating values were increased as a result of the torrefaction severity (from 20 MJ/kg for both raw biomasses to 30 MJ/kg at 350 °C). The highest mass losses were obtained at the highest temperature (67.35 and 65.04 %w for almond shells and olive stones, respectively, at 350 °C). The fixed carbon value also increased, being higher than 67 %w for torrefaction at 350 °C. The large-scale torrefaction at 350 °C (45 min) of these biomasses was carried out in a continuous pilot plant. The solids were characterized as well, and their properties were close to those of the biomasses torrefied in the laboratory-scale batch reactor under the same conditions. This thermal treatment provided biochars with all the required properties to be used as reducing materials in metallurgy.

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“…One refers to oxidative pyrolysis, which consists of introducing a small amount of air to stimulate the heterogeneous reactions and supply energy for the pyrolytic process (Çetinkaya and Yürüm 2000;Senneca et al 2002;Daouk et al 2015). Another is referred to as exothermic pyrolysis, where exothermicity conditions are revealed only in terms of particle-pyrolytic products interactions, under a completely inert atmosphere (Kilzer and Broido 1965;Yang et al 2007;Di Blasi et al 2017). Our study fits in the second case.…”

Section: Introductionsupporting

confidence: 53%

On the strong exothermicity of fecal matter pyrolysis under an inert atmosphere

Bittencourt

Martins

2020

Braz. J. Chem. Eng.

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Understanding the role of the exothermic pyrolysis is important for the design of reactors and gasifiers that seek to convert or even destroy fecal matter. In the present work, we reveal clear experimental evidence of fecal matter exothermic pyrolysis from human, pig, and chicken, under the conditions of differential scanning calorimetry. The results suggested that the strong exothermicity is related to the presence of inorganic elements in feces, Fe, Cu, Si, Pb, and Al, catalyzing the exothermic reactions, such as the partial fixed carbon oxidation and the inorganic reduction reactions. The pig feces presented the highest inorganic content, and the lowest fixed carbon content, 4.21 wt%. For all samples, the exothermicity of pyrolysis overcame endothermic reactions, leading to a maximum positive balance of 631.84 J/g. The pyrolysis efficiency reached values up to 10%. Based on the experimental evidence, a conceptual mechanism leading to exothermicity was drew for heterogeneous and homogeneous exothermic reactions affecting positively the overall energy balance of pyrolysis.

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On the Experimental Evidence of Exothermicity in Wood and Biomass Pyrolysis

Cited by 43 publications

References 74 publications

Pyrolysis Kinetics of Hydrochars Produced from Brewer’s Spent Grains

Pyrolysis Kinetics of Hydrochars Produced from Brewer’s Spent Grains

Upscaling Severe Torrefaction of Agricultural Residues to Produce Sustainable Reducing Agents for Non-Ferrous Metallurgy

On the strong exothermicity of fecal matter pyrolysis under an inert atmosphere

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