Kinetic study and modelling of char combustion in TGA in isothermal conditions

The purpose of this work is the kinetic study of biomass char combustion in isothermal conditions in TGA. This char was obtained from fast pyrolysis of beech bark pellet in a fluidized bed reactor at 850 °C and atmospheric pressure. Kinetic study of isothermal char combustion was performed for temperatures up to 400 °C, oxygen partial pressures ranging from 5065 to 21,273 Pa and a char particles size of 25 μm. Mass transfer effects around and within the crucible were thoroughly characterized by naphthalene vaporization. Oxygen diffusion was found to have no effect on char combustion for temperatures below 400 °C. A novel method including the transfer function of the TGA which describes the variation of oxygen partial pressure just after switching the gas from inert to reactive in the TGA was taken into consideration in the kinetic modelling. Two kinetic models (the Grain Model and the Random Pore Model) were used to determine kinetic parameters. The Grain Model was found to be in very good agreement with experimental data. Values of activation energy and reaction order with respect to oxygen are respectively equal to 124 kJ/mol and 0.74. Besides, the maximum combustion rate commonly observed in the literature during char combustion was found to be the result of the non-uniform oxygen partial pressure in the TGA at the initial stage of the char combustion.

[1]  R. Warnecke,et al.  Gasification of biomass: comparison of fixed bed and fluidized bed gasifier , 2000 .

[2]  Alan K. Burnham,et al.  ICTAC Kinetics Committee recommendations for performing kinetic computations on thermal analysis data , 2011 .

[3]  C. Wen,et al.  Reactivity of Coal and Char. 2. In Oxygen-Nitrogen Atmosphere , 1977 .

[4]  M. P. Morales,et al.  Biomass gasification for electricity generation: Review of current technology barriers , 2013 .

[5]  Rolando Zanzi,et al.  Rapid high-temperature pyrolysis of biomass in a free-fall reactor , 1996 .

[6]  N. Mahinpey,et al.  A comprehensive experimental procedure for CO2 coal gasification: Is there really a maximum reaction rate? , 2014 .

[7]  Johan E. Hustad,et al.  Steam Gasification of Wood Char and the Effect of Hydrogen Inhibition on the Chemical Kinetics , 2000 .

[8]  R. Gupta,et al.  Influence of carbonization conditions on the gasification of acacia and eucalyptus wood chars by carbon dioxide , 1994 .

[9]  C. Y. Wen,et al.  NONCATALYTIC HETEROGENEOUS SOLID-FLUID REACTION MODELS , 1968 .

[10]  RajenderKumar Gupta,et al.  Influence of pyrolysis conditions on the structure and gasification reactivity of biomass chars , 2004 .

[11]  Atsushi Tsutsumi,et al.  Effect of heating rate on steam gasification of biomass. 1. Reactivity of char , 2003 .

[12]  N. Mahinpey,et al.  Kinetic study of coal steam and CO2 gasification: A new method to reduce interparticle diffusion , 2015 .

[13]  D. D. Perlmutter,et al.  A random pore model for fluid‐solid reactions: I. Isothermal, kinetic control , 1980 .

[14]  F. Dullien.  Porous Media: Fluid Transport and Pore Structure , 1979 .

[15]  R. Hurt,et al.  Semi-global intrinsic kinetics for char combustion modeling Entry 2 has also been referred to as , 2001 .

[16]  V. Cozzani.  Reactivity in Oxygen and Carbon Dioxide of Char Formed in the Pyrolysis of Refuse-Derived Fuel , 2000 .

[17]  R. Essenhigh.  RATE EQUATIONS FOR THE CARBON-OXYGEN REACTION : AN EVALUATION OF THE LANGMUIR ADSORPTION ISOTHERM AT ATMOSPHERIC PRESSURE , 1991 .

[18]  J. Parlange.  Porous Media: Fluid Transport and Pore Structure , 1981 .

[19]  P. A. Jensen,et al.  The Influence of Inorganic Materials on the Thermal Deactivation of Fuel Chars , 2001 .

[20]  Normand M. Laurendeau,et al.  Heterogeneous Kinetics of Coal Char Gasification and Combustion , 1979 .

[21]  Mehrdji Hemati,et al.  Pyrolysis of biomass in a batch fluidized bed reactor: Effect of the pyrolysis conditions and the nature of the biomass on the physicochemical properties and the reactivity of char , 2016 .

[22]  Ammar Khawam,et al.  Solid‐State Kinetic Models: Basics and Mathematical Fundamentals , 2006 .

[23]  Colomba Di Blasi,et al.  Modeling chemical and physical processes of wood and biomass pyrolysis , 2008 .

[24]  Guangwen Xu,et al.  Characterization of Char Gasification in a Micro Fluidized Bed Reaction Analyzer , 2014 .

[25]  Colomba Di Blasi,et al.  Combustion and gasification rates of lignocellulosic chars , 2009 .

[26]  A. Bridgwater.  The technical and economic feasibility of biomass gasification for power generation , 1995 .

[27]  Robert H. Essenhigh,et al.  Influence of pressure on the combustion rate of carbon , 1996 .

[28]  Arturo Gomez,et al.  Review of gasification fundamentals and new findings: Reactors, feedstock, and kinetic studies , 2016 .

[29]  Ammar Khawam,et al.  Role of isoconversional methods in varying activation energies of solid-state kinetics , 2005 .

[30]  P. Ollero,et al.  Diffusional effects in TGA gasification experiments for kinetic determination , 2002 .

[31]  Takashi Kashiwagi,et al.  Global kinetic constants for thermal oxidative degradation of a cellulosic paper , 1992 .

[32]  M. Antal,et al.  Combustion Kinetics of Corncob Charcoal and Partially Demineralized Corncob Charcoal in the Kinetic Regime , 2006 .

[33]  S. Schulze,et al.  Heat and mass transfer within thermogravimetric analyser: From simulation to improved estimation of kinetic data for char gasification , 2017 .

[34]  M. V. Gil,et al.  Kinetic Parameters and Reactivity for the Steam Gasification of Coal Chars Obtained under Different Pyrolysis Temperatures and Pressures , 2011 .

[35]  James W. Evans,et al.  Gas-solid reactions , 1976 .

[36]  Marco J. Castaldi,et al.  Catalyst Properties and Catalytic Performance of Char from Biomass Gasification , 2012 .

[37]  A. Gómez-Barea,et al.  Reaction-diffusion model of TGA gasification experiments for estimating diffusional effects , 2005 .

[38]  Colomba Di Blasi,et al.  Reactivities of some biomass chars in air , 1999 .

[39]  A. Cukierman,et al.  Kinetic Study of the Reaction of Different Hardwood Sawdust Chars with Oxygen. Chemical and Structural Characterization of the Samples , 1993 .

[40]  W. Prins,et al.  Combustion Kinetics of Char Obtained by Flash Pyrolysis of Pine Wood , 1998 .

[41]  B. Ozum,et al.  CO2 GASIFICATION KINETICS OF TWO ALBERTA COAL CHARS , 1991 .

[42]  G Kabir,et al.  A thermogravimetric analysis of the combustion kinetics of karanja (Pongamia pinnata) fruit hulls char. , 2016, Bioresource technology.

[43]  Muhammad Usman,et al.  Coal gasification in CO2 atmosphere and its kinetics since 1948: A brief review , 2011 .

[44]  B. Stanmore,et al.  The combustion characteristics of char from pulverized bagasse , 1992 .

[45]  John B. Agnew,et al.  Gasification of a South Australian low-rank coal with carbon dioxide and steam: kinetics and reactivity studies , 1998 .

[46]  Mohammad Asadullah,et al.  Effects of biomass char structure on its gasification reactivity. , 2010, Bioresource technology.

[47]  Hiromitsu Matsuda,et al.  Gasification rate analysis of coal char with a pressurized drop tube furnace , 2002 .

[48]  Christopher R. Shaddix,et al.  Combustion kinetics of coal chars in oxygen-enriched environments , 2006 .

[49]  F. Golfier,et al.  Influence of the pyrolysis heating rate on the steam gasification rate of large wood char particles , 2006 .

[50]  K. Sakanishi,et al.  Effect of pyrolysis conditions on gasification reactivity of woody biomass-derived char , 2009 .

[51]  María U. Alzueta,et al.  Pyrolysis of eucalyptus at different heating rates: studies of char characterization and oxidative reactivity , 2005 .

[52]  C. Blasi,et al.  Global Kinetics of Wood Char Devolatilization and Combustion , 2003 .

[53]  J. C. Abanades,et al.  Determination of biomass char combustion reactivities for FBC applications by a combined method , 2001 .

[54]  N. Standish,et al.  Gasification of single wood charcoal particles in CO2 , 1988 .