Heat requirement for fixed bed pyrolysis of beechwood chips

The evaluation of heat of pyrolysis reactions at conditions relevant to the industrial practice is of great importance from the point of view of reactor design. Here, the evolution of heat during the pyrolysis of beechwood chips was experimentally measured in a lab-scale fixed bed pyrolysis system....

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Bibliographic Details
Published in:Energy (Oxford) 2019-07, Vol.178, p.145-157
Main Authors: Ábrego, J., Atienza-Martínez, M., Plou, F., Arauzo, J.
Format: Article
Language:English
Subjects:
Biomass pyrolysis
Cellulose
Chips (electronics)
Enthalpy
Evolution
Exothermic reactions
Fixed beds
Heat
Heat for pyrolysis
Hemicellulose
High temperature
Lab-scale fixed bed pyrolysis
Lignin
Pyrolysis
Reactor design
Temperature
Temperature effects
Temperature gradients
Wood
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Summary:The evaluation of heat of pyrolysis reactions at conditions relevant to the industrial practice is of great importance from the point of view of reactor design. Here, the evolution of heat during the pyrolysis of beechwood chips was experimentally measured in a lab-scale fixed bed pyrolysis system. Wood was heated and pyrolyzed by means of heat transferred from a mass of surrounding inert material (sand) initially heated at temperatures between 400 and 800 °C. Monitoring the evolution of temperatures in the system allowed calculation of heat for pyrolysis (QP) as a function of wood bed temperature. At pyrolysis conditions where slow heating rates of the wood bed are realized, changes in QP were clearly linked to the decomposition of the individual constituents of biomass (cellulose, hemicellulose and lignin), with consecutive exothermic and endothermic stages. When high temperature gradients were present, these stages were simultaneous and QP continuously increased with temperature, reaching 550 kJ kg−1. Under these circumstances, a correlation is provided for QP (T) up to 556 °C. The enthalpy of the pyrolysis reactions (ΔHP) was also estimated. Results show good coincidence with previously reported literature values. The proposed experimental system could be useful for determining heat requirements of pyrolysis under different operational conditions. [Display omitted] •Novel experimental system and procedure for determining heat for pyrolysis (QP).•Evolution of QP as a function of pyrolysis temperature is described.•Enthalpy of pyrolysis reactions (ΔHP) is estimated as a function of temperature.•Heat requirements are clearly linked to decomposition of biomass components.
ISSN:0360-5442
1873-6785
DOI:10.1016/j.energy.2019.04.078