Kinetic Study of NO Reduction over Biomass Char under Dynamic Conditions

This paper reports an experimental study of the NO−char reaction using two types of biomasswheat straw and eucalyptus wood. The experiments were performed in a fixed bed reactor at 1023−1173 K with NO inlet concentrations ranging from 50 to 1500 ppmv. The char was produced in-situ at the reaction temperature, and a special interest of the study was to measure the initial rate constant before significant char thermal deactivation had occurred. Separate experiments were carried out to investigate when the influence of volatiles on NO reduction could be neglected and the observed rate constant was only due to the heterogeneous NO−char interaction. The kinetic expressions for the initial rate obtained under these dynamic conditions are the following:  − rNO = 3.26 × 104 × exp(−11092/T) × CNO0.45 mol/(kg C in char·s) for wheat straw, and − rNO = 3.55 × 103 × exp(− 9305.5/T) × CNO0.3 mol/(kg C in char·s) for eucalyptus wood. For comparison also the reaction rate constant at pseudo steady-state conditions was de...

[1]  B. Adams,et al.  Biomass as a reburning fuel: a specialized cofiring application. , 2000 .

[2]  Jan Erik Johnsson,et al.  Reduction of NO over Wheat Straw Char , 2001 .

[3]  Tadafumi Adschiri,et al.  Nitric oxide reduction by char and carbon monoxide: Fundamental kinetics of nitric oxide reduction in fluidizedbed combustion of coal , 1985 .

[4]  Eric M. Suuberg,et al.  A review of the kinetics of the nitric oxide-carbon reaction , 1997 .

[5]  P. Chambrion,et al.  C−NO reaction in the presence of O2 , 1998 .

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

[7]  P. Chambrion,et al.  Role of N-Containing Surface Species on NO Reduction by Carbon , 1998 .

[8]  János M. Beér,et al.  Kinetics of the NOcarbon reaction at fluidized bed combustor conditions , 1983 .

[9]  Robert H. Hurt,et al.  Thermal Annealing of Chars from Diverse Organic Precursors under Combustion-like Conditions , 2000 .

[10]  Hans Erik Jannerup,et al.  Experimental investigation of no from pulverized char combustion , 2000 .

[11]  W. Hecker,et al.  Kinetics of NO reduction by char: Effects of coal rank , 1998 .

[12]  James A. Miller,et al.  Reburning using Several Hydrocarbon Fuels: A Kinetic Modeling Study , 1998 .

[13]  J. Gibbins,et al.  Structural ordering in high temperature coal chars and the effect on reactivity , 1999 .

[14]  J. Moulijn,et al.  Towards a unified theory of reactions of carbon with oxygen-containing molecules , 1995 .

[15]  Adel F. Sarofim,et al.  NO/char reactions at pulverized coal flame conditions , 1981 .

[16]  A. Jensen,et al.  Experimental study of char thermal deactivation , 2002 .

[17]  J. Swinehart,et al.  The Oxidation of Cardon by Nitric Oxide , 1959 .

[18]  S. N. Upadhyay,et al.  Particle-Fluid Mass Transfer in Fixed and Fluidized Beds , 1977 .

[19]  I. Aarna,et al.  A study of the reaction order of the NO-carbon gasification reaction , 1998 .

[20]  R. Schlögl,et al.  Reaction of NO with carbonaceous materials: 1. reaction and adsorption of NO on ashless carbon black , 2000 .

[21]  R. Kandiyoti,et al.  NO release and reactivity of chars during combustion: The effect of devolatilization temperature and heating rate , 1996 .

[22]  G. Soete.  Heterogeneous N2O and NO formation from bound nitrogen atoms during coal char combustion , 1991 .

[23]  A. Jensen,et al.  Kinetic Analysis of Char Thermal Deactivation , 2000 .

[24]  T. Ganga Devi,et al.  Gasification of biomass chars in air : Effect of heat treatment temperature , 2000 .

[25]  A. Jensen,et al.  Activation Energy Distribution of Thermal Annealing of a Bituminous Coal , 2003 .

[26]  Ron Zevenhoven,et al.  The reactivity of chars from coal, peat and wood towards NO, with and without CO , 1998 .

[27]  J. Calo,et al.  Studies on the reduction of nitric oxide by carbon: the nitric oxide-carbon gasification reaction , 1992 .

[28]  Robert H. Hurt,et al.  Structural and compositional transformations of biomass chars during combustion , 1995 .

[29]  David W. Pershing,et al.  REDUCTION OF NITRIC OXIDE ON THE CHAR SURFACE AT PULVERIZED COMBUSTION CONDITIONS , 2002 .

[30]  Takeshi Suzuki,et al.  Study on the Carbon-Nitric Oxide Reaction in the Presence of Oxygen , 1994 .

[31]  Á. Linares-Solano,et al.  NO reduction by activated carbons. VII: Some mechanistic aspects of uncatalyzed and catalyzed reaction , 1996 .

[32]  Eric M. Suuberg,et al.  The role of carbon monoxide in the NO-carbon reaction , 1999 .

[33]  Á. Linares-Solano,et al.  Potassium-Containing Coal Chars as Catalysts for NOx Reduction in the Presence of Oxygen , 1998 .

[34]  James A. Miller,et al.  Kinetic modeling of hydrocarbon/nitric oxide interactions in a flow reactor , 1998 .

[35]  R. Bilbao,et al.  Simplified kinetic model of the chemistry in the reburning zone using natural gas , 1995 .

[36]  R. T. Yang,et al.  Unified Mechanism of Alkali and Alkaline Earth Catalyzed Gasification Reactions of Carbon by CO2 and H2O , 1997 .