Fast pyrolysis of biomass: A review of relevant aspects. Part I: Parametric study (original) (raw)
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Biomass conversion to chemicals and fuels through fast pyrolysis shows great potential but requires a more fundamental approach for its deployment. To this end, molecularbased kinetic modeling is starting to play a central role in the prediction of the molecular composition of bio-oil. A molecular-level representation of biomass provides the start point for the generation of detailed pyrolysis reaction networks for both the condensed and the gas phases. Significant progress has been made for cellulose, glucosebased carbohydrates, and lignin, together with the incorporation of the catalytic effects of minerals. Ab initio techniques are widely used to discriminate between reaction mechanisms and to calculate kinetic parameters. Automatic kinetic model generation is expected to play an even more important role in fast pyrolysis as it does already today. Experimental techniques enabled to obtain intrinsic kinetics and to decouple the timescales between reaction kinetics and analytic techniques. This greatly benefits the improvement of detailed kinetic models. The prospects for achieving a first-principles based kinetic model of biomass fast pyrolysis are promising. However, significant work is still needed to couple condensed-and gas-phase reaction networks.
Biomass Fast Pyrolysis: Experimental Analysis and Modeling Approach †
Energy & Fuels, 2010
A single particle model able to predict the evolution of the products yields during biomass fast pyrolysis is developed. Mass balances equations based on a kinetic scheme of solid phase pyrolysis are coupled to heat transfer phenomena. This model is solved by the finite volume method. The model results are compared to experimental data obtained in an image furnace where biomass pellets are submitted to a controlled and concentrated radiation. Heat fluxes used are similar to those encountered in fluidized bed (0.2 -0.8 x 10 6 W.m -2 ). The comparison between the experimental and simulated data shows that the model correctly simulates the time-evolution of the products formation, but the kinetic parameters should be optimized in order to represent precisely the final products yields.
Pyrolysis of thick biomass particles: Experimental and kinetic modelling
Chemical Engineering Transactions, 2013
The aim of this work is to analyze some new experimental data of pyrolysis of thick woody biomass particles with the help of a general and comprehensive mathematical model. This multiphase and multiscale problem involves strong interactions between chemical kinetics, both in the solid and in the gas phase, and heat/mass transfer phenomena. Detailed experimental measurements have been obtained in an original lab scale reactor. This setup is designed to measure the products yielded along the pyrolysis of a single biomass (beech) particle as well as the temperature profiles into the sample. Experiments are carried out with pyrolysis temperatures ranging between 723 K and 1073 K. Lower-temperature pyrolysis data for poplar from a second reactor are also presented. These results constitute a very useful data set to tune and validate a predictive multistep kinetic model of biomass pyrolysis (Ranzi et al. 2008) and to analyse and discuss the relative effect of different phenomena. The thermal behavior of the pyrolysis process is particularly highlighted.
Chemical Kinetics of Biomass Pyrolysis
Energy & Fuels, 2008
This paper analyzes the main kinetic features of biomass pyrolysis, devolatilization, and the gas phase reactions of the released species. Three complex steps are faced in sequence: the characterization of biomasses, the description of the release of the species, and finally, their chemical evolution in the gas phase. Biomass is characterized as a mixture of reference constituents: cellulose, hemicellulose, and lignin. This assumption is verified versus experimental data, mainly relating to thermal degradation of different biomasses. Devolatilization of biomasses is a complex process in which several chemical reactions take place in both the gas and the condensed phase alongside the mass and thermal resistances involved in the pyrolysis process. A novel characterization of the released species is applied in the proposed devolatilization models. The successive gas phase reactions of released species are included into an existing detailed kinetic scheme of pyrolysis and oxidation of hydrocarbon fuels. Comparisons with experimental measurements in a drop tube reactor confirm the high potentials of the proposed modeling approach.
Biomass Pyrolysis Kinetics: A Review of Molecular-Scale Modeling Contributions
Brazilian Journal of Chemical Engineering
Decades of classical research on pyrolysis of lignocellulosic biomass has not yet produced a generalized formalism for design and prediction of reactor performance. Plagued by the limitations of experimental techniques such as thermogravimetric analysis (TGA) and extremely fast heating rates and low residence times to achieve high conversion to useful liquid products, researchers are now turning to molecular modeling to gain insights. This contribution briefly summarizes prior reviews along the historical path towards kinetic modeling of biomass pyrolysis and focusses on the more recent work on molecular modeling and the associated experimental efforts to validate model predictions. Clearly a new era of molecular-scale modelingdriven inquiry is beginning to shape the research landscape and influence the description of how cellulose and associated hemicellulose and lignin depolymerize to form the many hundreds of potential products of pyrolysis.
Journal of the Energy Institute
Pyrolysis is a versatile technology for exploiting diversified feedstocks to produce a wide range of products, including biochar, bio-oil, and syngas with high potential in diverse applications. The cardinal motivation of pyrolysis research is to productively use diverse biomass to reduce adverse impacts on ecology and enhance process economics. However, complex reactions of pyrolysis pose operational challenges. Thus, the present review targets the reaction mechanisms and kinetics of pyrolysis to enhance the understanding for better process control, improved performance, and product distribution. Pyrolysis mechanisms of the major structural components of biomass, such as cellulose, lignin, and hemicellulose, as well as proteins, lipids, and carbohydrates, are discussed in detail. Various modeling techniques and tools, viz., mathematical, kinetic, computational fluid dynamic modeling, and machine learning algorithms, have been employed to better understand the pyrolysis mechanisms and product distribution. In addition, the most critical challenges, namely aerosol formation, tar formation and their removal mechanisms, that severely impact the pyrolysis process and products are identified and reported. Thus, the present work critically discusses state-of-art biomass pyrolysis, focusing on the reaction mechanism, modeling, and associated challenges to overcome, given that the pyrolysis products and the process are enhanced.
Fast pyrolysis of biomass: advances in science and technology: a book review.pdf
Journal of Cleaner Production, 2019
Fast pyrolysis of biomass: Advances in science and technology: A book review Fast Pyrolysis of Biomass: Advances in Science and Technology Edited by Robert C. Brown and Kaige Wang, published by Royal Society of Chemistry, 2017, Price: £149.00 (Exclusive of Taxes); PDF eISBN: 978-1-78801-024-5; doi:10.1039/9781788010245-FP001; Page No. 276 (Fig. 1).
New Advances in the Fast Pyrolysis of Biomass
Journal of Biobased Materials and Bioenergy, 2012
The need to change the existing energy model requires the development of advanced technologies capable of making use of renewable sources in a way that combines high efficiency, improved environmental sustainability and cost-effectiveness. Fast pyrolysis is a novel technology capable of converting lignocellulosic biomass into combustible bio-oil with product yields typically above 70 wt%. This transformation brings about notable economic and technical advantages which affect the storage, transportation, processing and utilization of this energy source. Research and development in the fast pyrolysis of biomass has been absorbing substantial amounts of human and economic resources over the last two decades, resulting in notable advances in various areas including: design and construction of robust and efficient pyrolysis reactors; characterization and upgrading of pyrolysis bio-oils; novel technologies capable of making use of the energy and chemical potential of the bio-oil. On the verge of an upsurge in the commercial exploitation of this technology, this paper provides an updated review of its chemical basis, a description of chemical and fuel characteristics of bio-oils and a critical analysis of upgrading alternatives and potential applications. In addition, field information has been gathered from key players in the fast pyrolysis market regarding alternative reactor configurations and the characteristics of the most representative commercial and demonstration plants operating around the world.