Characteristics of Biochar Obtained by Pyrolysis of Residual Forest Biomass at Different Process Scales

In this work, the pyrolysis process and the characteristics of biochar produced using a bench-scale fixed-bed reactor and a prototype-scale auger reactor were studied. Residual forest biomass (RFB) from acacia, broom, gorse, and giant reed was used as feedstock. Besides information on pyrolysis char...

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Main Authors: Márcia Santos, Ana Carolina Morim, Mariana Videira, Flávio Silva, Manuel Matos, Luís A. C. Tarelho
Format: Article
Language:English
Published: MDPI AG 2024-09-01
Series:Energies
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Online Access:https://www.mdpi.com/1996-1073/17/19/4861
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author Márcia Santos
Ana Carolina Morim
Mariana Videira
Flávio Silva
Manuel Matos
Luís A. C. Tarelho
author_facet Márcia Santos
Ana Carolina Morim
Mariana Videira
Flávio Silva
Manuel Matos
Luís A. C. Tarelho
author_sort Márcia Santos
collection DOAJ
description In this work, the pyrolysis process and the characteristics of biochar produced using a bench-scale fixed-bed reactor and a prototype-scale auger reactor were studied. Residual forest biomass (RFB) from acacia, broom, gorse, and giant reed was used as feedstock. Besides information on pyrolysis characteristics of these specific biomass species from the Iberian Peninsula, new knowledge on the understanding of how results from small-scale reactors can be used to predict the behavior of higher-scale and continuous-operation reactors is offered. Batch pyrolysis was carried out using 40 g of biomass sample in a fixed-bed reactor with a heating rate of 20 °C∙min<sup>−1</sup>, pyrolysis temperature of 450 and 550 °C, and a residence time of 30 min, while for the continuous process it was used a prototype of an auger reactor with continuous operation with a biomass flow rate up to 1 kg/h, with temperatures of 450 and 550 °C, and a solids residence time of 5 min. The biochar yield was in the range of 0.26 to 0.36 kg/kg biomass dry basis, being similar for both types of reactors and slightly lower when using the auger reactor. The proximate analysis of the biochar shows volatile matter in the range 0.10 to 0.27 kg/kg biochar dry basis, fixed carbon in the range 0.65 to 0.84 kg/kg biochar dry basis, and ash in the range 0.04 to 0.08 kg/kg biochar dry basis. The carbon, oxygen, and hydrogen content of the biochar was in the range of 0.71 to 0.81, 0.09 to 0.22, and 0.02 to 0.03 kg/kg biochar dry basis, respectively. The results show that the up-scaling of the reactor and regime of operation does not have an important influence on the yield and characteristics of the biochar produced. The biochar obtained in the two types of reactors has characteristics appropriate for environmental applications, such as an additive to improve soil properties. It is possible to see that the characteristics of the biochar are influenced by the type of biomass and the conditions and parameters of the process; therefore, it is of major importance to control and know of these conditions, especially when considering upscaling scenarios.
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spelling doaj-art-c4c4171239e14b3593e903d49846e2da2025-08-20T01:47:45ZengMDPI AGEnergies1996-10732024-09-011719486110.3390/en17194861Characteristics of Biochar Obtained by Pyrolysis of Residual Forest Biomass at Different Process ScalesMárcia Santos0Ana Carolina Morim1Mariana Videira2Flávio Silva3Manuel Matos4Luís A. C. Tarelho5Department of Environment and Planning, Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, PortugalDepartment of Environment and Planning, Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, PortugalDepartment of Environment and Planning, Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, PortugalDepartment of Environment and Planning, Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, PortugalDepartment of Environment and Planning, Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, PortugalDepartment of Environment and Planning, Centre for Environmental and Marine Studies (CESAM), University of Aveiro, 3810-193 Aveiro, PortugalIn this work, the pyrolysis process and the characteristics of biochar produced using a bench-scale fixed-bed reactor and a prototype-scale auger reactor were studied. Residual forest biomass (RFB) from acacia, broom, gorse, and giant reed was used as feedstock. Besides information on pyrolysis characteristics of these specific biomass species from the Iberian Peninsula, new knowledge on the understanding of how results from small-scale reactors can be used to predict the behavior of higher-scale and continuous-operation reactors is offered. Batch pyrolysis was carried out using 40 g of biomass sample in a fixed-bed reactor with a heating rate of 20 °C∙min<sup>−1</sup>, pyrolysis temperature of 450 and 550 °C, and a residence time of 30 min, while for the continuous process it was used a prototype of an auger reactor with continuous operation with a biomass flow rate up to 1 kg/h, with temperatures of 450 and 550 °C, and a solids residence time of 5 min. The biochar yield was in the range of 0.26 to 0.36 kg/kg biomass dry basis, being similar for both types of reactors and slightly lower when using the auger reactor. The proximate analysis of the biochar shows volatile matter in the range 0.10 to 0.27 kg/kg biochar dry basis, fixed carbon in the range 0.65 to 0.84 kg/kg biochar dry basis, and ash in the range 0.04 to 0.08 kg/kg biochar dry basis. The carbon, oxygen, and hydrogen content of the biochar was in the range of 0.71 to 0.81, 0.09 to 0.22, and 0.02 to 0.03 kg/kg biochar dry basis, respectively. The results show that the up-scaling of the reactor and regime of operation does not have an important influence on the yield and characteristics of the biochar produced. The biochar obtained in the two types of reactors has characteristics appropriate for environmental applications, such as an additive to improve soil properties. It is possible to see that the characteristics of the biochar are influenced by the type of biomass and the conditions and parameters of the process; therefore, it is of major importance to control and know of these conditions, especially when considering upscaling scenarios.https://www.mdpi.com/1996-1073/17/19/4861biomasspyrolysischarauger reactorfixed-bed batch reactor
spellingShingle Márcia Santos
Ana Carolina Morim
Mariana Videira
Flávio Silva
Manuel Matos
Luís A. C. Tarelho
Characteristics of Biochar Obtained by Pyrolysis of Residual Forest Biomass at Different Process Scales
Energies
biomass
pyrolysis
char
auger reactor
fixed-bed batch reactor
title Characteristics of Biochar Obtained by Pyrolysis of Residual Forest Biomass at Different Process Scales
title_full Characteristics of Biochar Obtained by Pyrolysis of Residual Forest Biomass at Different Process Scales
title_fullStr Characteristics of Biochar Obtained by Pyrolysis of Residual Forest Biomass at Different Process Scales
title_full_unstemmed Characteristics of Biochar Obtained by Pyrolysis of Residual Forest Biomass at Different Process Scales
title_short Characteristics of Biochar Obtained by Pyrolysis of Residual Forest Biomass at Different Process Scales
title_sort characteristics of biochar obtained by pyrolysis of residual forest biomass at different process scales
topic biomass
pyrolysis
char
auger reactor
fixed-bed batch reactor
url https://www.mdpi.com/1996-1073/17/19/4861
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