Coal Char-CO2 Gasification Measurements and Modeling in a Pressurized Flat-Flame Burner

A pressurized flat-flame burner (PFFB) was used to conduct coal gasification studies. The PFFB was designed to provide an environment with laminar, dispersed entrained flow, with particle heating rates of ∼105 K/s, pressures of up to 15 atm, and gas temperatures of up to 2000 K. Residence times were varied from 30 to 700 ms in this study. Char gasification studies by CO2 were conducted on a subbituminous coal and 4 bituminous coals in the PFFB. Pressures of 5, 10, and 15 atm were used with gas compositions of 20, 40, and 90 mol % CO2. Gas conditions with peak temperatures of 1700 to 2000 K were used, which resulted in char particle temperatures of 1000 to 1800 K. Three gasification models were developed to fit and analyze the gasification data. A simple first-order model was used to show that the measured gasification rates were far below the film-diffusion limit. The other two models, designated CCK and CCKN, were based on three versions of the CBK models. CCKN used an nth-order kinetic mechanism, and CC...

[1]  D. Zeng.  Effects of Pressure on Coal Pyrolysis at High Heating Rates and Char Combustion , 2005 .

[2]  Alan W. Scaroni,et al.  Effect of pressure on the devolatilization and swelling behaviour of a softening coal during rapid heating , 1991 .

[3]  T. Fletcher,et al.  Development and Application of a Correlation of 13C NMR Chemical Structural Analyses of Coal Based on Elemental Composition and Volatile Matter Content , 1999 .

[4]  L. Douglas Smoot,et al.  Coal Combustion and Gasification , 1985 .

[5]  D. G. Roberts,et al.  Char Gasification with O2, CO2, and H2O: Effects of Pressure on Intrinsic Reaction Kinetics , 2000 .

[6]  B. M. Gibbs,et al.  Gasification kinetics of an Indonesian sub-bituminous coal-char with CO2 at elevated pressure , 2001 .

[7]  John Lucas,et al.  Effect of Pressure on Char Formation during Pyrolysis of Pulverized Coal , 2004 .

[8]  Rafael Kandiyoti,et al.  CO2 and steam-gasification in a high-pressure wire-mesh reactor: the reactivity of Daw Mill coal and combustion reactivity of its chars , 1999 .

[9]  Alan R. Kerstein,et al.  Chemical percolation model for devolatilization. 3. Direct use of carbon-13 NMR data to predict effects of coal type , 1992 .

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

[11]  Joseph W. Hogge,et al.  Coal Swelling Model for Pressurized High Particle Heating Rate Pyrolysis Applications , 2012 .

[12]  Robert H. Hurt,et al.  A Kinetic Model of Carbon Burnout in Pulverized Coal Combustion , 1998 .

[13]  Shiro Kajitani,et al.  CO2 gasification rate analysis of coal char in entrained flow coal gasifier , 2006 .

[14]  D. G. Roberts,et al.  Gasification behaviour of Australian coals at high temperature and pressure , 2006 .

[15]  Thomas H. Fletcher,et al.  Modeling high-pressure char oxidation using langmuir kinetics with an effectiveness factor , 2000 .

[16]  M. Clark,et al.  Swelling properties and intrinsic reactivities of coal chars produced at elevated pressures and high heating rates , 2005 .

[17]  A. Megaritis,et al.  Gasification and char combustion reactivities of Daw Mill coal in wire-mesh and ‘hot-rod’ reactors , 1997 .

[18]  Terry Wall,et al.  An experimental study on the effect of system pressure on char structure of an Australian bituminous coal , 2000 .

[19]  T. Fletcher,et al.  Coal Swelling Model for High Heating Rate Pyrolysis Applications , 2011 .

[20]  D. G. Roberts,et al.  Kinetics of Char Gasification with CO2 under Regime II Conditions: Effects of Temperature, Reactant, and Total Pressure , 2010 .

[21]  R. Essenhigh,et al.  Autocorrelations of kinetic parameters in coal and char reactions , 1990 .

[22]  Robert H. Hurt,et al.  Unified high-temperature char combustion kinetics for a suite of coals of various rank , 1992 .

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

[24]  D. G. Roberts,et al.  A kinetic analysis of coal char gasification reactions at high pressures , 2006 .

[25]  T. Fletcher.  Swelling properties of coal chars during rapid pyrolysis and combustion , 1993 .

[26]  Haiping Yang,et al.  Influence of Pressure on Coal Pyrolysis and Char Gasification , 2007 .

[27]  J. Carberry.  The micro‐macro effectiveness factor for the reversible catalytic reaction , 1962 .

[28]  Kenneth B. Bischoff,et al.  Effectiveness factors for general reaction rate forms , 1965 .

[29]  Haiping Yang,et al.  Pressurized Pyrolysis and Gasification of Chinese Typical Coal Samples , 2008 .

[30]  R. Hurt,et al.  Coal conversion submodels for design applications at elevated pressures. Part I. devolatilization and char oxidation , 2003 .

[31]  D. G. Roberts,et al.  On the Effects of High Pressure and Heating Rate during Coal Pyrolysis on Char Gasification Reactivity , 2003 .

[32]  G. J. Germane,et al.  Char oxidation at elevated pressures , 1995 .

[33]  R. Kandiyoti,et al.  Factors governing reactivity in low temperature coal gasification. Part 1. An attempt to correlate results from a suite of coals with experiments on maceral concentrates , 2000 .

[34]  Randy C. Shurtz.  Effects of Pressure on the Properties of Coal Char Under Gasification Conditions at High Initial Heating Rates , 2011 .

[35]  Robert H. Hurt,et al.  Mechanisms of extinction and near-extinction in pulverized solid fuel combustion , 2000 .

[36]  F. F. Peng,et al.  Reactivities of in situ and ex situ coal chars during gasification in steam at 1000–1400°C , 1995 .

[37]  C. H. Bartholomew,et al.  Decreases in the Swelling and Porosity of Bituminous Coals during Devolatilization at High Heating Rates , 1995 .

[38]  Stephen Niksa,et al.  Coal conversion submodels for design applications at elevated pressures. Part II. Char gasification , 2004 .

[39]  T. Fletcher,et al.  Effects of Pressure on Coal Pyrolysis and Char Morphology , 2005 .

[40]  D. G. Roberts,et al.  The Significance of Char Morphology to the Analysis of High-Temperature Char−CO2 Reaction Rates† , 2010 .