The gasification reactivity of high-heating-rate chars in single and mixed atmospheres of H2O and CO2

Gasification reactivity of high-heating-rate chars (HHR-chars) in steam, carbon dioxide and their mixtures was investigated in a new macro-TG experimental device. The higher reactivity of the HHR-chars was highlighted by a comparison with reference chars prepared at a low heating rate (LHR-chars). It was found that the char reactivity in a mixed atmosphere of steam and carbon dioxide can be expressed as the sum of the individual reactivities obtained in single-atmosphere gasification experiments. This result was not dependent on the pyrolysis heating rate. In addition, gas-alternation gasification experiments – for both HHR-chars and LHR-chars – showed that gasifying the char with CO2 up to 30% of conversion does not affect its reactivity to H2O. Altogether, the results tend to indicate that the two reactant gases H2O and CO2 react on separate active sites when mixed atmospheres are used, and that CO2 does not affect the char structure to favor or inhibit the char–H2O gasification reaction.

[1]  Wei Liu,et al.  Effect of pyrolysis conditions on the char gasification with mixtures of CO2 and H2O , 2013 .

[2]  Hongwei Wu,et al.  Biochar as a Fuel: 3. Mechanistic Understanding on Biochar Thermal Annealing at Mild Temperatures and Its Effect on Biochar Reactivity , 2011 .

[3]  Chun-Zhu Li,et al.  Changes in Char Structure during the Gasification of Mallee Wood: Effects of Particle Size and Steam Supply , 2012 .

[4]  M. Uddin,et al.  Gasification of woody biomass char with CO2: The catalytic effects of K and Ca species on char gasification reactivity , 2011 .

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

[6]  J. Xiang,et al.  Effect of temperature on gas composition and char structural features of pyrolyzed agricultural residues. , 2011, Bioresource technology.

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

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

[9]  D. G. Roberts,et al.  Char gasification in mixtures of CO2 and H2O: Competition and inhibition , 2007 .

[10]  S. Kajitani,et al.  Modeling of coal char gasification in coexistence of CO2 and H2O considering sharing of active sites , 2013 .

[11]  Hai Zhang,et al.  Kinetic studies of char gasification by steam and CO2 in the presence of H2 and CO , 2010 .

[12]  W. V. Swaaij,et al.  Gasification of coal-derived chars in synthesis gas mixtures under intraparticle mass-transfer-controlled conditions , 1986 .

[13]  Iain S. Donnison,et al.  Influence of particle size on the analytical and chemical properties of two energy crops , 2007 .

[14]  Marco J Castaldi,et al.  CO2 as a carbon neutral fuel source via enhanced biomass gasification. , 2009, Environmental science & technology.

[15]  Rolando Zanzi,et al.  Thermochemical treatment of biomass in a flow of steam or in a mixture of steam and carbon dioxide , 2000 .

[16]  G. Florides,et al.  Global warming and carbon dioxide through sciences. , 2009, Environment international.

[17]  Xiu-li Yin,et al.  Effects of metal catalysts on CO2 gasification reactivity of biomass char. , 2009, Biotechnology advances.

[18]  Prabir Basu,et al.  Biomass Gasification and Pyrolysis: Practical Design and Theory , 2010 .

[19]  A. Gómez-Barea,et al.  Modeling of biomass gasification in fluidized bed , 2010 .

[20]  Delani Njapha,et al.  Reaction kinetics of pulverized coal-chars derived from inertinite-rich coal discards: Gasification with carbon dioxide and steam , 2006 .

[21]  Hongwei Wu,et al.  Effect of Alkali and Alkaline Earth Metallic Species on Biochar Reactivity and Syngas Compositions during Steam Gasification , 2010 .

[22]  Chun-Zhu Li,et al.  Drastic changes in biomass char structure and reactivity upon contact with steam , 2008 .

[23]  Susanna Nilsson,et al.  Gasification reactivity of char from dried sewage sludge in a fluidized bed , 2012 .

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

[25]  Chun-Zhu Li,et al.  Effects of gasifying agent on the evolution of char structure during the gasification of Victorian brown coal , 2013 .

[26]  P. Bonelli,et al.  Effect of pyrolysis temperature on composition, surface properties and thermal degradation rates of Brazil Nut shells. , 2001, Bioresource technology.

[27]  P. Ollero,et al.  The CO2 gasification kinetics of olive residue , 2003 .

[28]  R. Dhillon,et al.  Mitigation of global warming through renewable biomass , 2013 .

[29]  Alberto Gómez-Barea,et al.  Diffusional effects in CO2 gasification experiments with single biomass char particles. 1. Experimental investigation , 2006 .

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

[31]  P. Salatino,et al.  A Semi-Detailed Kinetic Model of Char Combustion with Consideration of Thermal Annealing , 2011 .

[32]  S. Salvador,et al.  Gasification of woodchip particles: Experimental and numerical study of char–H2O, char–CO2, and char–O2 reactions , 2011 .

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

[34]  A. Gómez-Barea,et al.  Gasification of char from dried sewage sludge in fluidized bed: Reaction rate in mixtures of CO2 and H2O , 2013 .

[35]  J. Lédé.  Biomass Pyrolysis: Comments on Some Sources of Confusions in the Definitions of Temperatures and Heating Rates , 2010 .

[36]  M. Hanna,et al.  THERMOCHEMICAL BIOMASS GASIFICATION—A REVIEW OF THE CURRENT STATUS OF THE TECHNOLOGY , 2009 .

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

[38]  T. Liliedahl,et al.  Modelling of char-gas reaction kinetics , 1997 .

[39]  D. Vamvuka,et al.  Gasification of waste biomass chars by carbon dioxide via thermogravimetry. Part I: Effect of mineral matter , 2011 .