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Pyrolysis of centimeter-scale woody biomass particles: kinetic modeling and experimental validation Michele Corbetta, Alessio Frassoldati, Hayat Bennadji, Krystle Smith, Michelle J. Serapiglia, Guillaume Gauthier, Thierry Melkior, Eliseo Ranzi, and Elizabeth M. Fisher Energy Fuels, Just Accepted Manuscript • DOI: 10.1021/ef500525v • Publication Date (Web): 27 May 2014 Downloaded from http://pubs.acs.org on June 3, 2014
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Energy & Fuels
Pyrolysis of centimeter-scale woody biomass particles: kinetic modeling and experimental validation Michele Corbettaa, Alessio Frassoldatia, Hayat Bennadjib, Krystle Smithb#, Michelle J. Serapigliac†, Guillaume Gauthierd§, Thierry Melkiord, Eliseo Ranzia, Elizabeth M. Fisherb*
a
CMIC, Politecnico di Milano, Piazza L. da Vinci 32, 20133 Milano, Italy; bSibley School of
Mechanical and Aerospace Engineering, Cornell University, Ithaca, NY, 14853, USA; cNew York State Agricultural Experiment Station, Department of Horticulture, Cornell University, Geneva, NY 14456, USA; dCEA-LITEN Biomass Technologies Laboratory, 17 rue des Martyrs – 38054 Grenoble Cedex 09, France. KEYWORDS biomass pyrolysis; kinetic mechanism; thermochemistry; modeling; heat transfer; thermally thick particle. ABSTRACT Pyrolysis of centimeter-scale wood particles is of practical interest, and also provides a sensitive test of pyrolysis models, especially their thermochemistry. In this paper we present an updated comprehensive pyrolysis model including chemical reactions and transport of heat and species, implemented independently in two different software environments. Results of the model are compared to experimental results of three independent sets of centimeter-scale experiments. Temperatures, mass losses, and rate of production of several gaseous and light tar species are included in the comparisons. Predictions and experiments agree qualitatively, and in most cases have reasonable quantitative agreement. We also report comparisons of model predictions to literature data obtained in other regimes (thermogravimetric analysis and
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homogeneous tar cracking) in order to demonstrate that predictive capabilities of the model have not been compromised by the modifications presented here. INTRODUCTION Diverse routes can be used to convert the chemical energy of biomass into thermal energy, fuels, and other useful products. When considering thermal routes, the ability to model the effect of process conditions such as external heating rate and temperature on conversion times and product yields is clearly valuable to the engineers responsible for process design. A kinetic model of pyrolysis is a key building block that can be combined with intra-particle transport models, reactor models, and gas phase kinetics to predict the outcomes of industrial processes. Biomass particle size has an important impact on pyrolysis behavior, as can be seen by considering the pyrolysis number, Py, the ratio of timescales for kinetics vs heat transfer,1 and the Biot number, Bi, the ratio of timescales for internal vs external heat transfer. Small particles, used in many industrial devices such as entrained flow reactors, typically are pyrolyzed under “thermally thin,” kinetically controlled conditions (Py>>1; Bi
