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Combining model-free and model-fitting methods for the determination of the global kinetics of cashew nut and coconut shells pyrolysis
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.ORCID iD: 0000-0002-1837-5439
KTH, School of Industrial Engineering and Management (ITM), Materials Science and Engineering, Energy and Furnace Technology.
2008 (English)In: 27th Annual International Conference on Thermal Treatment Technologies 2008, 2008, 688-708 p.Conference paper, Published paper (Other academic)
Abstract [en]

Thermal characterisation of unique tropical biomass, as coconut (CcNS) and cashew nut shells (CNS) has been the main focus of a research being conducted by the authors of this study. In this work, the objective was assess avoid the influence of the compensation factor in the kinetics results obtained from model fitting approach. This was done by combining model-free methods and model fitting procedures for the determination of pyrolysis global kinetic parameters of these two tropical biomasses. Thus, thermogravimetric analysis was performed at 10, 30 and 100 K/min in an inert atmosphere. Data analysis was primarily performed using model-free methods. Then, results from these analyses were used as reference for the determination of the reaction order. The results were then compared with those obtained previously through Coats-Redfern method. A good agreement between all the results was achieved and the experimental data were predicted with high precision. The average frequency factor and activation energy for CcNS pyrolysis were 3.16E14 1/s and 195.73±8.29 kJ/mol, respectively. For CNS, they were 1.66E08 1/s and 122.34±18.48 kJ/mol, respectively.\br| The averaged deviation was 12.39 1/s for A and 15.233kJ/mol for Eact, in CNS pyrolysis, while for CcNS was 9.33 1/s for A and 12.661kJ/mol for Eact. It had been proved that model-free methods are reliable auxiliar tools for the determination of apparent kinetics especially, as input data in modelling techniques as well as for generating primary data for model-fitting techniques.

Place, publisher, year, edition, pages
2008. 688-708 p.
Keyword [en]
pyrolysis, kinetics, isoconversional, model-free, model-fitting methods
National Category
Engineering and Technology
Identifiers
URN: urn:nbn:se:kth:diva-9139Scopus ID: 2-s2.0-55849136212ISBN: 978-160560379-7 (print)OAI: oai:DiVA.org:kth-9139DiVA: diva2:25244
Conference
27th Annual International Conference on Thermal Treatment Technologies 2008. Montreal, QC. 12 May 2008 - 16 May 2008
Note
QC 20100914. Updated from submitted to published, 20120315Available from: 2008-09-24 Created: 2008-09-24 Last updated: 2012-03-15Bibliographically approved
In thesis
1. Fundamental Study of two Selected Tropical Biomasses for Energy: coconut and cashew nut shells
Open this publication in new window or tab >>Fundamental Study of two Selected Tropical Biomasses for Energy: coconut and cashew nut shells
2008 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

 Cashew nut and coconut shells are two potential renewable and environmentally friendly energy sources that are commonly found as agro-industrial wastes in tropical countries. Despite this fact, they are not yet widely studied as such. Given this lack of specific technical and reliable data, technologies for their conversion into energy cannot be designed with confidence as it happens with other commonly studied biomass feedstock. Thus, the need to generate these data guided this research in order to provide technical information for the designing of appropriate thermochemical conversion technologies for energy generation, particularly, in remote areas, where electricity grid is neither a feasible nor an affordable solution.Among thermochemical processes, pyrolysis plays a key role as it is found in both combustion and gasification at their earlier stages. In both technologies, pyrolysis products are generated and later submitted to further transformations according to the process in use.Hence, pyrolysis was selected for thermal characterisation of cashew nut and coconut shells. The main characteristics envisaged are i) pyrolysis profiles; ii) global, semi-global and individual kinetics; iii) pyrolysis global and individual yields; iv) modelled pyrolysis yields at high heating rates; and, v)char combustion kinetics and reactivity. The main technique used for experimental data generation is thermogravimetry and FTIR spectroscopy. Data experimentally generated from TG and TG-FTIR experiments were processed through different methods and codes, such as the Coats and Redfern model-fitting method, the modelfree methods of Ozawa-Flynn-Wall, Friedman and ASTM E698, for semi-global and global kinetics; DAEM and FG-Biomass were used for pyrolysis individual kinetics and yields determination. Proximate and ultimate analyses were performed as well.The study revealed peculiar characteristics compared to the commonly known lignocellulosic biomass. The volatiles content was above 66%w/w; hemicelluloses DTG peak did not overlap with the cellulose peak; the global pyrolysis activation energies were around 200 and 120 kJ/mol for coconut and cashew nut shells, respectively. Hemicelluloses and cellulose showed varying activation energies as 130-216 and 155-208 kJ/mol, respectively. Char combustion showed two steps with activation energies of 135 and 121 kJ/mol (cashew nut shells); 105 and 190kJ/mol (coconut shells). Individual yields and kinetics were determined for 17 compounds, including tars. These data are of key importance for modelling and the consequent data generation for the designing of appropriate thermochemical energy for these biomasses.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. xi, 71 p.
Keyword
Cashew nut shells, coconut shells, biomass, thermogravimetry, pyrolysis, kinetics, combustion
National Category
Engineering and Technology
Identifiers
urn:nbn:se:kth:diva-9138 (URN)978-91-7415-079-7 (ISBN)
Public defence
2008-09-30, F3, Lindstedtsvägen 26, Stockholm, 10:00 (English)
Opponent
Supervisors
Note
QC 20100914Available from: 2008-09-24 Created: 2008-09-24 Last updated: 2010-09-14Bibliographically approved

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Yang, Weihong

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