2005
Proceedings Articles
Ayllón, María; Gea, Gloria; Murillo, María Benita; Sánchez, José Luis; Arauzo, Jesús
Kinetic study of meat and bone meal pyrolysis: An evaluation and comparison of different possible kinetic models Proceedings Article
In: Journal of Analytical and Applied Pyrolysis, pp. 445–453, Elsevier, 2005, ISSN: 01652370.
@inproceedings{Ayllon2005,
title = {Kinetic study of meat and bone meal pyrolysis: An evaluation and comparison of different possible kinetic models},
author = {María Ayllón and Gloria Gea and María Benita Murillo and José Luis Sánchez and Jesús Arauzo},
doi = {10.1016/j.jaap.2004.11.022},
issn = {01652370},
year = {2005},
date = {2005-08-01},
booktitle = {Journal of Analytical and Applied Pyrolysis},
volume = {74},
number = {1-2},
pages = {445--453},
publisher = {Elsevier},
abstract = {Alternative treatments such as gasification or pyrolysis need to be developed for the disposal of meat and bone meal (MBM). The present work is focussed on a study of the pyrolysis of MBM in a thermobalance in order to compare different possible kinetic methods of obtaining information about the MBM decomposition process. Previous experiments were performed to establish the optimum operating conditions. Several dynamic experiments were then carried out at low heating rates (5, 10, 15 and 20 °C/min) up to 900 °C under the optimum operating conditions obtained, 250-350 $mu$m, 15 mg and 100 cm 3/min NTP of nitrogen. Different kinetic models were tested and compared, considering one fraction or two, three or four fractions decomposing simultaneously. The basis of comparison was the goodness of the fit with regard to the linear correlation coefficients of the lines $alpha$ experimental = $alpha$calculated and d$alpha$/dT experimental = d$alpha$/dTcalculated. The most valuable kinetic expressions and the kinetic parameters obtained are shown. The kinetic model which best describes the decomposition of MBM considers four fractions decomposing simultaneously following a second order equation (F2). However, other models tested with lower fitting parameters values can also be considered satisfactory depending on the degree of accuracy required in the kinetics. The results obtained with the different models were compared with those found in the literature. textcopyright 2005 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {inproceedings}
}
Alternative treatments such as gasification or pyrolysis need to be developed for the disposal of meat and bone meal (MBM). The present work is focussed on a study of the pyrolysis of MBM in a thermobalance in order to compare different possible kinetic methods of obtaining information about the MBM decomposition process. Previous experiments were performed to establish the optimum operating conditions. Several dynamic experiments were then carried out at low heating rates (5, 10, 15 and 20 °C/min) up to 900 °C under the optimum operating conditions obtained, 250-350 $mu$m, 15 mg and 100 cm 3/min NTP of nitrogen. Different kinetic models were tested and compared, considering one fraction or two, three or four fractions decomposing simultaneously. The basis of comparison was the goodness of the fit with regard to the linear correlation coefficients of the lines $alpha$ experimental = $alpha$calculated and d$alpha$/dT experimental = d$alpha$/dTcalculated. The most valuable kinetic expressions and the kinetic parameters obtained are shown. The kinetic model which best describes the decomposition of MBM considers four fractions decomposing simultaneously following a second order equation (F2). However, other models tested with lower fitting parameters values can also be considered satisfactory depending on the degree of accuracy required in the kinetics. The results obtained with the different models were compared with those found in the literature. textcopyright 2005 Elsevier B.V. All rights reserved.
Technical Reports
Ruiz, Joaquín
An Open-Ended Mass Balance Problem Technical Report
no. 1, 2005, ISSN: 2165-6428.
@techreport{Ruiz2005,
title = {An Open-Ended Mass Balance Problem},
author = {Joaquín Ruiz},
url = {http://www.chebro.es/},
issn = {2165-6428},
year = {2005},
date = {2005-01-01},
booktitle = {Chemical Engineering Education},
volume = {39},
number = {1},
pages = {22--27},
abstract = {Current "Class and Home Problems" article.},
keywords = {},
pubstate = {published},
tppubtype = {techreport}
}
Current “Class and Home Problems” article.
2004
Journal Articles
Sánchez, José Luis; Gea, Gloria; Gonzalo, Alberto; Bilbao, Rafael; Arauzo, Jesús
Kinetic study of the thermal degradation of alkaline straw black liquor in nitrogen atmosphere Journal Article
In: Chemical Engineering Journal, vol. 104, no. 1-3, pp. 1–6, 2004, ISSN: 13858947.
@article{Sanchez2004,
title = {Kinetic study of the thermal degradation of alkaline straw black liquor in nitrogen atmosphere},
author = {José Luis Sánchez and Gloria Gea and Alberto Gonzalo and Rafael Bilbao and Jesús Arauzo},
doi = {10.1016/j.cej.2004.06.003},
issn = {13858947},
year = {2004},
date = {2004-11-01},
journal = {Chemical Engineering Journal},
volume = {104},
number = {1-3},
pages = {1--6},
publisher = {Elsevier},
abstract = {The kinetics of solid weight loss in the pyrolysis of straw black liquor solids at low temperature (<500°C) has been studied by thermogravimetric techniques in nitrogen atmosphere. Isothermal and dynamic experiments have been performed. Assuming a first order for the thermal decomposition rate of the solid at a given temperature, the instantaneous kinetic constant for the same temperature diminishes as the reaction proceeds. This could be due mainly to the heterogeneity of straw black liquor solids. Both, the pre-exponential factor and the activation energy of the Arrhenius law, seem to vary linearly with the solid conversion. textcopyright 2004 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The kinetics of solid weight loss in the pyrolysis of straw black liquor solids at low temperature (<500°C) has been studied by thermogravimetric techniques in nitrogen atmosphere. Isothermal and dynamic experiments have been performed. Assuming a first order for the thermal decomposition rate of the solid at a given temperature, the instantaneous kinetic constant for the same temperature diminishes as the reaction proceeds. This could be due mainly to the heterogeneity of straw black liquor solids. Both, the pre-exponential factor and the activation energy of the Arrhenius law, seem to vary linearly with the solid conversion. textcopyright 2004 Elsevier B.V. All rights reserved.
Gea, Gloria; Sánchez, José Luis; Murillo, María Benita; Arauzo, Jesús
Kinetics of CO2 gasification of alkaline black liquor from wheat straw. Influence of CO and CO2 concentrations on the gasification rate Journal Article
In: Industrial and Engineering Chemistry Research, vol. 43, no. 13, pp. 3233–3241, 2004, ISSN: 08885885.
@article{Gea2004,
title = {Kinetics of CO2 gasification of alkaline black liquor from wheat straw. Influence of CO and CO2 concentrations on the gasification rate},
author = {Gloria Gea and José Luis Sánchez and María Benita Murillo and Jesús Arauzo},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ie034338o},
issn = {08885885},
year = {2004},
date = {2004-06-01},
journal = {Industrial and Engineering Chemistry Research},
volume = {43},
number = {13},
pages = {3233--3241},
publisher = {American Chemical Society},
abstract = {Interest in the use of nonwoody biomass as a raw material for pulp and paper production is growing worldwide. Moreover, new technologies are being developed to solve the problems caused by the silica present in alkaline black liquor (ABL) from straw in heat recovery systems. Because, among the various possible technologies, gasification is becoming attractive as a new alternative recovery system for ABL, in-depth studies of ABL gasification are therefore required. The present work is focused on the study of CO2 gasification of a char obtained from the ABL pyrolysis. Specifically, the influence of [CO] and [CO2] on the gasification rate at different gasification temperatures has been studied. The process may be described by a Langmuir-Hinshelwood equation for a specific range of operating conditions. The data obtained suggest that this operational range could be broader if the number of catalytic sites is considered as a function of [CO] and the final pyrolysis temperature rather than as constant.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Interest in the use of nonwoody biomass as a raw material for pulp and paper production is growing worldwide. Moreover, new technologies are being developed to solve the problems caused by the silica present in alkaline black liquor (ABL) from straw in heat recovery systems. Because, among the various possible technologies, gasification is becoming attractive as a new alternative recovery system for ABL, in-depth studies of ABL gasification are therefore required. The present work is focused on the study of CO2 gasification of a char obtained from the ABL pyrolysis. Specifically, the influence of [CO] and [CO2] on the gasification rate at different gasification temperatures has been studied. The process may be described by a Langmuir-Hinshelwood equation for a specific range of operating conditions. The data obtained suggest that this operational range could be broader if the number of catalytic sites is considered as a function of [CO] and the final pyrolysis temperature rather than as constant.
Mendiara, Teresa; Alzueta, María U; Millera, Ángela; Bilbao, Rafael
An augmented reduced mechanism for methane combustion Journal Article
In: Energy and Fuels, vol. 18, no. 3, pp. 619–627, 2004, ISSN: 08870624.
@article{Mendiara2004,
title = {An augmented reduced mechanism for methane combustion},
author = {Teresa Mendiara and María U Alzueta and Ángela Millera and Rafael Bilbao},
url = {http://www.me.berkeley.edu/},
doi = {10.1021/ef030111u},
issn = {08870624},
year = {2004},
date = {2004-05-01},
journal = {Energy and Fuels},
volume = {18},
number = {3},
pages = {619--627},
publisher = {American Chemical Society},
abstract = {An augmented reduced mechanism (ARM) for methane combustion has been developed from the detailed mechanism of Glarborg and co-workers (reported in 1998) that was formed by 447 elementary reversible reactions and 65 chemical species. First, an intermediate state of reduction, the skeletal mechanism, is reached by means of sensitivity analysis and reaction-rate analysis. After that, a systematic method for reducing mechanisms based on the steady-state hypothesis and the partial equilibrium assumption is used. The reduced mechanism is obtained via an algebraic procedure. This mechanism consists of 18 lumped reaction steps and 22 chemical species. Both the skeletal and reduced mechanisms are validated by comparison with the results predicted by the detailed mechanism for the main species in methane combustion (CH4, CO, and CO2) in a wide range of operating conditions and generally show good agreement.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An augmented reduced mechanism (ARM) for methane combustion has been developed from the detailed mechanism of Glarborg and co-workers (reported in 1998) that was formed by 447 elementary reversible reactions and 65 chemical species. First, an intermediate state of reduction, the skeletal mechanism, is reached by means of sensitivity analysis and reaction-rate analysis. After that, a systematic method for reducing mechanisms based on the steady-state hypothesis and the partial equilibrium assumption is used. The reduced mechanism is obtained via an algebraic procedure. This mechanism consists of 18 lumped reaction steps and 22 chemical species. Both the skeletal and reduced mechanisms are validated by comparison with the results predicted by the detailed mechanism for the main species in methane combustion (CH4, CO, and CO2) in a wide range of operating conditions and generally show good agreement.
Berrueco, César; Ceamanos, Jesús; Esperanza, Ernesto; Mastral, José Francisco
Experimental study of co-pyrolysis of polyethylene/sawdust mixtures Journal Article
In: Thermal Science, vol. 8, no. 2, pp. 65–80, 2004, ISSN: 0354-9836.
@article{Berrueco2004,
title = {Experimental study of co-pyrolysis of polyethylene/sawdust mixtures},
author = {César Berrueco and Jesús Ceamanos and Ernesto Esperanza and José Francisco Mastral},
doi = {10.2298/tsci0402065b},
issn = {0354-9836},
year = {2004},
date = {2004-01-01},
journal = {Thermal Science},
volume = {8},
number = {2},
pages = {65--80},
publisher = {National Library of Serbia},
abstract = {A study of the behavior of the thermal decomposition of mixtures of biomass and thermoplastics, such as polyethylene, is of interest for processes for the thermal recovery of industrial and urban wastes such as pyrolysis or gasification. No solid residue is formed during the thermal degradation of pure polyethylene. However, the addition of biomass,which generates char, can vary the product distribution and increase the heating value of the gas obtained. A study of the thermal degradation of pine sawdust, polyethylene and mixtures of polyethylene and pine sawdust has been carried out in a fluidised bed reactor. Experiments were carried out at five different temperatures: 640, 685, 730, 780, and 850 textordmasculineC. The yields and composition of the derived oil, wax, and gas were determined. The addition of polyethylene increases the gas production and decreases theproduction of waxes and liquids for the different temperatures tested. The main gases produced from the co-pyrolysis process were, at low temperatures, carbon monoxide, ethylene, carbon dioxide, propylene, butadiene, methane and pentadiene, while at high temperatures the gas composition changed drastically, the main components being carbon monoxide (more than 33 wt.%), ethylene, methane, benzene and hydrogen. The analysis of the liquid fraction shows a decrease of the concentration of oxygenated and aliphatic compounds.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A study of the behavior of the thermal decomposition of mixtures of biomass and thermoplastics, such as polyethylene, is of interest for processes for the thermal recovery of industrial and urban wastes such as pyrolysis or gasification. No solid residue is formed during the thermal degradation of pure polyethylene. However, the addition of biomass,which generates char, can vary the product distribution and increase the heating value of the gas obtained. A study of the thermal degradation of pine sawdust, polyethylene and mixtures of polyethylene and pine sawdust has been carried out in a fluidised bed reactor. Experiments were carried out at five different temperatures: 640, 685, 730, 780, and 850 textordmasculineC. The yields and composition of the derived oil, wax, and gas were determined. The addition of polyethylene increases the gas production and decreases theproduction of waxes and liquids for the different temperatures tested. The main gases produced from the co-pyrolysis process were, at low temperatures, carbon monoxide, ethylene, carbon dioxide, propylene, butadiene, methane and pentadiene, while at high temperatures the gas composition changed drastically, the main components being carbon monoxide (more than 33 wt.%), ethylene, methane, benzene and hydrogen. The analysis of the liquid fraction shows a decrease of the concentration of oxygenated and aliphatic compounds.
2003
Journal Articles
Gea, Gloria; Murillo, María Benita; Sánchez, José Luis; Arauzo, Jesús
Thermal Degradation of Alkaline Black Liquor from Wheat Straw. 2. Fixed-Bed Reactor Studies Journal Article
In: Industrial & Engineering Chemistry Research, vol. 42, no. 23, pp. 5782–5790, 2003, ISSN: 0888-5885.
@article{Gea2003b,
title = {Thermal Degradation of Alkaline Black Liquor from Wheat Straw. 2. Fixed-Bed Reactor Studies},
author = {Gloria Gea and María Benita Murillo and José Luis Sánchez and Jesús Arauzo},
url = {https://pubs.acs.org/sharingguidelines https://pubs.acs.org/doi/10.1021/ie030116e},
doi = {10.1021/ie030116e},
issn = {0888-5885},
year = {2003},
date = {2003-11-01},
journal = {Industrial & Engineering Chemistry Research},
volume = {42},
number = {23},
pages = {5782--5790},
publisher = {American Chemical Society},
abstract = {The usual problems experienced with common recovery boilers are aggravated in processes involving alkaline black liquor derived from straw. The consequent need to develop alternative processes for the use of black liquor for energy purposes, such as pyrolysis or gasification, requires a good understanding of the thermochemical behavior of this substance. There is, however, little information available. Part 1 of this work (Gea, G.; Murillo, M. B.; Arauzo, J. Ind. Eng. Chem. Res. 2002, 41, 4714), therefore, studied the thermal degradation of alkaline black liquor from straw in a thermogravimetric system. The present work also focuses on its pyrolysis. In particular, the influence has been analyzed of the final pyrolysis temperature (250-900 °C) and the heating rate (5-30 °C/min) on the product yields, gas composition, and specific surface area of the resulting char in a fixed-bed reactor. The results obtained show that both the energy recovery and the specific surface area of the char increase with a rise in the final pyrolysis temperature and the heating rate.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The usual problems experienced with common recovery boilers are aggravated in processes involving alkaline black liquor derived from straw. The consequent need to develop alternative processes for the use of black liquor for energy purposes, such as pyrolysis or gasification, requires a good understanding of the thermochemical behavior of this substance. There is, however, little information available. Part 1 of this work (Gea, G.; Murillo, M. B.; Arauzo, J. Ind. Eng. Chem. Res. 2002, 41, 4714), therefore, studied the thermal degradation of alkaline black liquor from straw in a thermogravimetric system. The present work also focuses on its pyrolysis. In particular, the influence has been analyzed of the final pyrolysis temperature (250-900 °C) and the heating rate (5-30 °C/min) on the product yields, gas composition, and specific surface area of the resulting char in a fixed-bed reactor. The results obtained show that both the energy recovery and the specific surface area of the char increase with a rise in the final pyrolysis temperature and the heating rate.
Mastral, José Francisco; Esperanza, Ernesto; Berrueco, César; Juste, Marta; Ceamanos, Jesús
Fluidized bed thermal degradation products of HDPE in an inert atmosphere and in air-nitrogen mixtures Journal Article
In: Journal of Analytical and Applied Pyrolysis, vol. 70, no. 1, pp. 1–17, 2003, ISSN: 01652370.
@article{Mastral2003,
title = {Fluidized bed thermal degradation products of HDPE in an inert atmosphere and in air-nitrogen mixtures},
author = {José Francisco Mastral and Ernesto Esperanza and César Berrueco and Marta Juste and Jesús Ceamanos},
doi = {10.1016/S0165-2370(02)00068-2},
issn = {01652370},
year = {2003},
date = {2003-10-01},
journal = {Journal of Analytical and Applied Pyrolysis},
volume = {70},
number = {1},
pages = {1--17},
publisher = {Elsevier},
abstract = {Different processes involving thermal decomposition such as incineration, pyrolysis, gasification or co-combustion are becoming important for energy generation using plastic wastes as combustible materials. The thermal degradation of the material, the product distribution and consequently the economics of the process are strongly influenced by the experimental conditions used. In this work, the thermal degradation of high-density polyethylene (HDPE) has been carried out using a fluidized bed reactor under different temperature conditions. Two types of experiments have been performed, pyrolysis experiments, in which nitrogen has been used as inert gas, and gasification experiments, meaning that the thermal decomposition has been carried out in a nitrogen-air mixture with low oxygen concentration. The influence of the operating parameters on the product distribution and gas composition has been investigated using GC and MS/GC for the analysis of the gas, wax and oil fractions obtained. The results obtained show a widely differing product yield in both processes. The main objective of the paper is a comparison of pyrolysis and gasification in terms of the generation of products of high heating value, and the energy requirements for the thermal degradation and production of residues and polyaromatic compounds. An optimum interval of operation temperatures is suggested in order to obtain high yield to gases of high heating values and low yield to PAHs. textcopyright 2002 Elsevier B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Different processes involving thermal decomposition such as incineration, pyrolysis, gasification or co-combustion are becoming important for energy generation using plastic wastes as combustible materials. The thermal degradation of the material, the product distribution and consequently the economics of the process are strongly influenced by the experimental conditions used. In this work, the thermal degradation of high-density polyethylene (HDPE) has been carried out using a fluidized bed reactor under different temperature conditions. Two types of experiments have been performed, pyrolysis experiments, in which nitrogen has been used as inert gas, and gasification experiments, meaning that the thermal decomposition has been carried out in a nitrogen-air mixture with low oxygen concentration. The influence of the operating parameters on the product distribution and gas composition has been investigated using GC and MS/GC for the analysis of the gas, wax and oil fractions obtained. The results obtained show a widely differing product yield in both processes. The main objective of the paper is a comparison of pyrolysis and gasification in terms of the generation of products of high heating value, and the energy requirements for the thermal degradation and production of residues and polyaromatic compounds. An optimum interval of operation temperatures is suggested in order to obtain high yield to gases of high heating values and low yield to PAHs. textcopyright 2002 Elsevier B.V. All rights reserved.
Alzueta, María U; Glarborg, Peter
Formation and destruction of CH2O in the exhaust system of a gas engine Journal Article
In: Environmental Science and Technology, vol. 37, no. 19, pp. 4512–4516, 2003, ISSN: 0013936X.
@article{Alzueta2003,
title = {Formation and destruction of CH2O in the exhaust system of a gas engine},
author = {María U Alzueta and Peter Glarborg},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/es026144q},
issn = {0013936X},
year = {2003},
date = {2003-10-01},
journal = {Environmental Science and Technology},
volume = {37},
number = {19},
pages = {4512--4516},
publisher = {American Chemical Society},
abstract = {A computational study of chemical reactions occurring in the exhaust system of natural gas engines has been conducted, emphasizing the formation and destruction of formaldehyde. The modeling was based on a detailed reaction mechanism, developed for describing oxidation of C1-C2 hydrocarbons and formaldehyde. The mechanism was validated against data from laboratory flow reactors and from the exhaust system of a full-scale gas engine. A parametric study of the exhaust system chemistry was performed, investigating the effect of temperature, stoichiometry, pressure, and exhaust gas composition. The results indicate a complexinteraction between unburned hydrocarbons (UHC), formaldehyde, and nitrogen oxides. Above 850 K, partial oxidation of unburned hydrocarbons may occur, resulting in net formation or net destruction of CH20 depending on the unburned hydrocarbons/CH20 ratio and the reaction conditions. At the typical unburned hydrocarbons/CH20 ratio of 1.0-1. 5% for gas engines, net formaldehyde formation may occur in the exhaust system if temperatures above 850 K are reached.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A computational study of chemical reactions occurring in the exhaust system of natural gas engines has been conducted, emphasizing the formation and destruction of formaldehyde. The modeling was based on a detailed reaction mechanism, developed for describing oxidation of C1-C2 hydrocarbons and formaldehyde. The mechanism was validated against data from laboratory flow reactors and from the exhaust system of a full-scale gas engine. A parametric study of the exhaust system chemistry was performed, investigating the effect of temperature, stoichiometry, pressure, and exhaust gas composition. The results indicate a complexinteraction between unburned hydrocarbons (UHC), formaldehyde, and nitrogen oxides. Above 850 K, partial oxidation of unburned hydrocarbons may occur, resulting in net formation or net destruction of CH20 depending on the unburned hydrocarbons/CH20 ratio and the reaction conditions. At the typical unburned hydrocarbons/CH20 ratio of 1.0-1. 5% for gas engines, net formaldehyde formation may occur in the exhaust system if temperatures above 850 K are reached.
Glarborg, Peter; Alzueta, María U; Kjærgaard, K; Dam-Johansen, Kim
Oxidation of formaldehyde and its interaction with nitric oxide in a flow reactor Journal Article
In: Combustion and Flame, vol. 132, no. 4, pp. 629–638, 2003, ISSN: 00102180.
@article{Glarborg2003,
title = {Oxidation of formaldehyde and its interaction with nitric oxide in a flow reactor},
author = {Peter Glarborg and María U Alzueta and K Kjærgaard and Kim Dam-Johansen},
doi = {10.1016/S0010-2180(02)00535-7},
issn = {00102180},
year = {2003},
date = {2003-03-01},
journal = {Combustion and Flame},
volume = {132},
number = {4},
pages = {629--638},
publisher = {Elsevier Inc.},
abstract = {The oxidation of formaldehyde in a flow reactor has been studied experimentally under diluted conditions at 800 to 1400 K and with the stoichiometry between fuel-rich and very lean. Of particular interest was the interaction of formaldehyde with nitrogen oxides. The results show that the oxidation of CH2O is initiated above 900 K, with the oxidation rate decreasing slightly with increasing [O2]. Addition of NO under fuel-rich conditions inhibits oxidation, while under lean conditions a mutually promoted oxidation of CH2O and NO is observed at 750-1100 K. Based partly on recent accurate measurements of key reactions of CH2O and HCO, a detailed reaction mechanism for the oxidation of formaldehyde under post-flame conditions is proposed. It provides a good description of the experimental measurements as well as data from the literature. textcopyright 2003 The Combustion Institute. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The oxidation of formaldehyde in a flow reactor has been studied experimentally under diluted conditions at 800 to 1400 K and with the stoichiometry between fuel-rich and very lean. Of particular interest was the interaction of formaldehyde with nitrogen oxides. The results show that the oxidation of CH2O is initiated above 900 K, with the oxidation rate decreasing slightly with increasing [O2]. Addition of NO under fuel-rich conditions inhibits oxidation, while under lean conditions a mutually promoted oxidation of CH2O and NO is observed at 750-1100 K. Based partly on recent accurate measurements of key reactions of CH2O and HCO, a detailed reaction mechanism for the oxidation of formaldehyde under post-flame conditions is proposed. It provides a good description of the experimental measurements as well as data from the literature. textcopyright 2003 The Combustion Institute. All rights reserved.
Gea, Gloria; Murillo, María Benita; Arauzo, Jesús; Frederick, W J
Swelling behavior of black liquor from soda pulping of wheat straw Journal Article
In: Energy and Fuels, vol. 17, no. 1, pp. 46–53, 2003, ISSN: 08870624.
@article{Gea2003,
title = {Swelling behavior of black liquor from soda pulping of wheat straw},
author = {Gloria Gea and María Benita Murillo and Jesús Arauzo and W J Frederick},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef0200469},
issn = {08870624},
year = {2003},
date = {2003-01-01},
journal = {Energy and Fuels},
volume = {17},
number = {1},
pages = {46--53},
publisher = {American Chemical Society},
abstract = {The primary aim of this research work was to characterize the swelling properties of black liquor and their dependence on the temperature and gas composition of the combustion or gasification environment. The measurements were made using an industrial black liquor from soda pumping of wheat straw. The swelling measurements were carried out in a single droplet reactor. This paper presents data that show the influence of the reactor temperature and the gas composition on the swelling during devolatilization, and compares the swelling characteristics of a straw black liquor with similar published data on black liquors from kraft pulping of wood. Experiments were carried out in inert, oxiding, and gasifying environments, at temperatures from 500 to 900°C. One interesting result was that the straw liquor swelled much more than most kraft or soda liquors from pulping of wood. Another result was that droplets subjected to hot gas atmospheres containing O2, CO2 and/or H2O(v) swelled less than those subjected to hot N2 atmospheres. The data obtained suggest that the straw soda black liquor would burn more rapidly than most kraft liquors from pulping of wood because of its high external surface area when swollen. This highly swelling liquor caused problems with fluidization when straw liquors were injected in a laboratory-scale fluidized bed gasifier.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The primary aim of this research work was to characterize the swelling properties of black liquor and their dependence on the temperature and gas composition of the combustion or gasification environment. The measurements were made using an industrial black liquor from soda pumping of wheat straw. The swelling measurements were carried out in a single droplet reactor. This paper presents data that show the influence of the reactor temperature and the gas composition on the swelling during devolatilization, and compares the swelling characteristics of a straw black liquor with similar published data on black liquors from kraft pulping of wood. Experiments were carried out in inert, oxiding, and gasifying environments, at temperatures from 500 to 900°C. One interesting result was that the straw liquor swelled much more than most kraft or soda liquors from pulping of wood. Another result was that droplets subjected to hot gas atmospheres containing O2, CO2 and/or H2O(v) swelled less than those subjected to hot N2 atmospheres. The data obtained suggest that the straw soda black liquor would burn more rapidly than most kraft liquors from pulping of wood because of its high external surface area when swollen. This highly swelling liquor caused problems with fluidization when straw liquors were injected in a laboratory-scale fluidized bed gasifier.
Gea, Gloria; Murillo, María Benita; Sánchez, José Luis; Bilbao, Rafael; Arauzo, Jesús
Straw black liquor gasification studies at the University of Zaragoza Journal Article
In: Pulp and Paper Canada, vol. 104, no. 3, pp. 44–48, 2003.
@article{Gea2003a,
title = {Straw black liquor gasification studies at the University of Zaragoza},
author = {Gloria Gea and María Benita Murillo and José Luis Sánchez and Rafael Bilbao and Jesús Arauzo},
url = {https://www.osti.gov/etdeweb/biblio/20341706},
year = {2003},
date = {2003-01-01},
journal = {Pulp and Paper Canada},
volume = {104},
number = {3},
pages = {44--48},
abstract = {Results of studies on the thermal behaviour of straw black liquor and fluidized bed gasification are discussed. Agglomeration of the bed and low gas yield, coupled with high tar formation, was observed during fluidized bed gasification. To avoid agglomeration a spouted bed reactor was used and the black liquor was pretreated to reduce its swelling. Attempt were made to reduce tar formation by adding a secondary catalyst (NiAlsub 2Osub 4) to the fluidized bed which is known to be useful in cracking tars formed during the pyrolysis stage. Results of selected additional studies on several variables such as the furnace temperature and gas composition on the swelling of a soda straw black liquor are also included},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Results of studies on the thermal behaviour of straw black liquor and fluidized bed gasification are discussed. Agglomeration of the bed and low gas yield, coupled with high tar formation, was observed during fluidized bed gasification. To avoid agglomeration a spouted bed reactor was used and the black liquor was pretreated to reduce its swelling. Attempt were made to reduce tar formation by adding a secondary catalyst (NiAlsub 2Osub 4) to the fluidized bed which is known to be useful in cracking tars formed during the pyrolysis stage. Results of selected additional studies on several variables such as the furnace temperature and gas composition on the swelling of a soda straw black liquor are also included
2002
Journal Articles
Olazar, Martín; Aguado, Roberto; Sánchez, José Luis; Bilbao, Rafael; Arauzo, Jesús
Thermal processing of straw black liquor in fluidized and spouted bed Journal Article
In: Energy and Fuels, vol. 16, no. 6, pp. 1417–1424, 2002, ISSN: 08870624.
@article{Olazar2002,
title = {Thermal processing of straw black liquor in fluidized and spouted bed},
author = {Martín Olazar and Roberto Aguado and José Luis Sánchez and Rafael Bilbao and Jesús Arauzo},
doi = {10.1021/ef020034n},
issn = {08870624},
year = {2002},
date = {2002-11-01},
journal = {Energy and Fuels},
volume = {16},
number = {6},
pages = {1417--1424},
abstract = {Nowadays, black liquor recovery is important for the economics of the pulp and paper production industry. As a result of the high capital cost of the recovery unit, the corrosive nature of the smelt, and the risk of smeltwater explosions, alternatives to the conventional recovery cycle are under research in order to achieve more efficient and environmentally cleaner processes. These alternatives fall into two categories: high-temperature and low-temperature, according to whether or not the melting point of the black liquor inorganics is reached. The advantage of low-temperature processes is to avoid the formation of smelt. In this work, the feasibility of the thermal processing at low temperature of straw black liquor in two different bench scale reactors has been tested. In the fluidized bed, the loss of fluidization due to bed agglomeration was found to be the main problem in the reactor used. The second reactor used, a spouted bed, presents different characteristics from the fluidized bed, and has been tested in order to overcome the agglomeration observed. Experiments in different operating conditions were carried out in order to get a basic knowledge about the behavior of this residue during pyrolysis, gasification, and combustion processes. To work below the melting point of the black liquor inorganics, reaction temperature was kept under 600°C. Liquid black liquor and dry black liquor were used as feedstocks. Nitrogen, air, and nitrogen-oxygen mixtures were considered as reaction atmospheres.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Nowadays, black liquor recovery is important for the economics of the pulp and paper production industry. As a result of the high capital cost of the recovery unit, the corrosive nature of the smelt, and the risk of smeltwater explosions, alternatives to the conventional recovery cycle are under research in order to achieve more efficient and environmentally cleaner processes. These alternatives fall into two categories: high-temperature and low-temperature, according to whether or not the melting point of the black liquor inorganics is reached. The advantage of low-temperature processes is to avoid the formation of smelt. In this work, the feasibility of the thermal processing at low temperature of straw black liquor in two different bench scale reactors has been tested. In the fluidized bed, the loss of fluidization due to bed agglomeration was found to be the main problem in the reactor used. The second reactor used, a spouted bed, presents different characteristics from the fluidized bed, and has been tested in order to overcome the agglomeration observed. Experiments in different operating conditions were carried out in order to get a basic knowledge about the behavior of this residue during pyrolysis, gasification, and combustion processes. To work below the melting point of the black liquor inorganics, reaction temperature was kept under 600°C. Liquid black liquor and dry black liquor were used as feedstocks. Nitrogen, air, and nitrogen-oxygen mixtures were considered as reaction atmospheres.
Alzueta, María U; Tena, A; Bilbao, Rafael
Pyridine conversion in a flow reactor and its interaction with nitric oxide Journal Article
In: Combustion Science and Technology, vol. 174, no. 10, pp. 151–169, 2002, ISSN: 00102202.
@article{Alzueta2002,
title = {Pyridine conversion in a flow reactor and its interaction with nitric oxide},
author = {María U Alzueta and A Tena and Rafael Bilbao},
url = {https://www.tandfonline.com/doi/abs/10.1080/00102200290021470},
doi = {10.1080/00102200290021470},
issn = {00102202},
year = {2002},
date = {2002-10-01},
journal = {Combustion Science and Technology},
volume = {174},
number = {10},
pages = {151--169},
publisher = {Taylor & Francis Group},
abstract = {An experimental study of the oxidation of pyridine both in the absence and in the presence of NO has been performed. The experiments were conducted in an isothermal quartz flow reactor at atmospheric pressure in the temperature range 700-1500 K. The influence of temperature, air excess ratio (corresponding to fuel-rich, stoichiometric, and lean conditions), and NO on the concentrations of CO, CO2, HCN, and NO has been analyzed. The current work contributes to a series of works on the conversion of volatile nitrogen compounds with experimental results related to pyridine. Also, a reaction mechanism based on various literature mechanisms has been used for simulating the experimental results.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An experimental study of the oxidation of pyridine both in the absence and in the presence of NO has been performed. The experiments were conducted in an isothermal quartz flow reactor at atmospheric pressure in the temperature range 700-1500 K. The influence of temperature, air excess ratio (corresponding to fuel-rich, stoichiometric, and lean conditions), and NO on the concentrations of CO, CO2, HCN, and NO has been analyzed. The current work contributes to a series of works on the conversion of volatile nitrogen compounds with experimental results related to pyridine. Also, a reaction mechanism based on various literature mechanisms has been used for simulating the experimental results.
Gea, Gloria; Murillo, María Benita; Arauzo, Jesús
Thermal degradation of alkaline black liquor from straw. Thermogravimetric study Journal Article
In: Industrial and Engineering Chemistry Research, vol. 41, no. 19, pp. 4714–4721, 2002, ISSN: 08885885.
@article{Gea2002,
title = {Thermal degradation of alkaline black liquor from straw. Thermogravimetric study},
author = {Gloria Gea and María Benita Murillo and Jesús Arauzo},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ie020283z},
issn = {08885885},
year = {2002},
date = {2002-09-01},
journal = {Industrial and Engineering Chemistry Research},
volume = {41},
number = {19},
pages = {4714--4721},
publisher = {American Chemical Society},
abstract = {Both pyrolysis and gasification can be considered as alternatives to conventional boilers for recovering chemicals and energy from black liquor. The present work is focused on the study of pyrolysis of alkaline black liquor from straw, and its interest is enhanced by the fact that the material used has hardly been studied before. The influence has been studied of the final pyrolysis temperature (500-900 °C), the heating rate (5-30 °C/min), and the addition of a determined CO concentration in the N2 atmosphere (5-40% vol) on both the final solid conversion and the devolatilization rate. The results show that the thermal decomposition of the organic matter fraction of black liquor takes place at temperatures below 550 °C in N2 atmosphere. The weight loss observed at temperatures higher than 550 °C is mainly due to reduction reactions of alkaline compounds by the carbon. The final solid conversion and the devolatilization rate are also noticeably influenced by the addition of a certain CO flow rate in N2 atmosphere.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Both pyrolysis and gasification can be considered as alternatives to conventional boilers for recovering chemicals and energy from black liquor. The present work is focused on the study of pyrolysis of alkaline black liquor from straw, and its interest is enhanced by the fact that the material used has hardly been studied before. The influence has been studied of the final pyrolysis temperature (500-900 °C), the heating rate (5-30 °C/min), and the addition of a determined CO concentration in the N2 atmosphere (5-40% vol) on both the final solid conversion and the devolatilization rate. The results show that the thermal decomposition of the organic matter fraction of black liquor takes place at temperatures below 550 °C in N2 atmosphere. The weight loss observed at temperatures higher than 550 °C is mainly due to reduction reactions of alkaline compounds by the carbon. The final solid conversion and the devolatilization rate are also noticeably influenced by the addition of a certain CO flow rate in N2 atmosphere.
García, Lucía; Benedicto, A; Romeo, E; Salvador, María L; Arauzo, Jesús; Bilbao, Rafael
Hydrogen production by steam gasification of biomass using Ni-Al coprecipitated catalysts promoted with magnesium Journal Article
In: Energy and Fuels, vol. 16, no. 5, pp. 1222–1230, 2002, ISSN: 08870624.
@article{Garcia2002,
title = {Hydrogen production by steam gasification of biomass using Ni-Al coprecipitated catalysts promoted with magnesium},
author = {Lucía García and A Benedicto and E Romeo and María L Salvador and Jesús Arauzo and Rafael Bilbao},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef020035f},
issn = {08870624},
year = {2002},
date = {2002-09-01},
journal = {Energy and Fuels},
volume = {16},
number = {5},
pages = {1222--1230},
publisher = {American Chemical Society},
abstract = {Ni-Al coprecipitated catalysts promoted with magnesium have been prepared using the rising and the constant pH techniques, two precipitant agents [(1) KOH and K2CO3, and (2) NH4OH)] and different metal contents. Catalyst characterization by temperature-programmed reduction and CO2 reforming of methane as a test reaction served to select the appropriate catalysts for use in the steam gasification of biomass. The catalysts selected were NiMgAl2O5, prepared at constant pH and precipitated with KOH and K2CO3; NiMgAl4O8 and NiMgAl1.24O3.86, both prepared at increasing pH with NH4OH. Biomass steam gasification experiments were carried out at 700 °C and at atmospheric pressure using different steam/biomass (S/B) and catalyst weightY biomass flow rate (W/B) ratios. From an analysis of the results obtained, the initial activity and stability of the catalysts have been studied. The NiMgAl2O5 catalyst presents the best performance showing the highest initial activity and stability. This work evidences an improvement of the NiMgAl2O5 catalyst with respect to the previously studied NiAl2O4 catalyst.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ni-Al coprecipitated catalysts promoted with magnesium have been prepared using the rising and the constant pH techniques, two precipitant agents [(1) KOH and K2CO3, and (2) NH4OH)] and different metal contents. Catalyst characterization by temperature-programmed reduction and CO2 reforming of methane as a test reaction served to select the appropriate catalysts for use in the steam gasification of biomass. The catalysts selected were NiMgAl2O5, prepared at constant pH and precipitated with KOH and K2CO3; NiMgAl4O8 and NiMgAl1.24O3.86, both prepared at increasing pH with NH4OH. Biomass steam gasification experiments were carried out at 700 °C and at atmospheric pressure using different steam/biomass (S/B) and catalyst weightY biomass flow rate (W/B) ratios. From an analysis of the results obtained, the initial activity and stability of the catalysts have been studied. The NiMgAl2O5 catalyst presents the best performance showing the highest initial activity and stability. This work evidences an improvement of the NiMgAl2O5 catalyst with respect to the previously studied NiAl2O4 catalyst.
Oliva, Miriam; Alzueta, María U; Millera, Ángela; Bilbao, Rafael
An approach to the analysis of mixing in reactive systems Journal Article
In: Chemical Engineering and Technology, vol. 25, no. 4, pp. 417–419, 2002, ISSN: 09307516.
@article{Oliva2002,
title = {An approach to the analysis of mixing in reactive systems},
author = {Miriam Oliva and María U Alzueta and Ángela Millera and Rafael Bilbao},
doi = {10.1002/1521-4125(200204)25:4<417::AID-CEAT417>3.0.CO;2-0},
issn = {09307516},
year = {2002},
date = {2002-04-01},
journal = {Chemical Engineering and Technology},
volume = {25},
number = {4},
pages = {417--419},
abstract = {A simple mixing approach for use in reactive systems is considered. This mixing approach has so far been applied to reburning and selective non-catalytic reduction (SNCR) processes, two well-known techniques to reduce NOx emissions. Detailed kinetic models together with the mixing approaches, based on the work of Zwietering, are used to simulate both the chemistry and mixing of the reactants. Two different configurations for the mixing approach have been considered: the so-called direct and reverse approach. The study includes a comparison between different experimental results obtained in pilot installations and theoretical results calculated with the present approach.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A simple mixing approach for use in reactive systems is considered. This mixing approach has so far been applied to reburning and selective non-catalytic reduction (SNCR) processes, two well-known techniques to reduce NOx emissions. Detailed kinetic models together with the mixing approaches, based on the work of Zwietering, are used to simulate both the chemistry and mixing of the reactants. Two different configurations for the mixing approach have been considered: the so-called direct and reverse approach. The study includes a comparison between different experimental results obtained in pilot installations and theoretical results calculated with the present approach.
Bilbao, Rafael; Mastral, José Francisco; Lana, José A; Ceamanos, Jesús; Aldea, María E; Betrán, Mónica
A model for the prediction of the thermal degradation and ignition of wood under constant and variable heat flux Journal Article
In: Journal of Analytical and Applied Pyrolysis, vol. 62, no. 1, pp. 63–82, 2002, ISSN: 01652370.
@article{Bilbao2002,
title = {A model for the prediction of the thermal degradation and ignition of wood under constant and variable heat flux},
author = {Rafael Bilbao and José Francisco Mastral and José A Lana and Jesús Ceamanos and María E Aldea and Mónica Betrán},
doi = {10.1016/S0165-2370(00)00214-X},
issn = {01652370},
year = {2002},
date = {2002-01-01},
journal = {Journal of Analytical and Applied Pyrolysis},
volume = {62},
number = {1},
pages = {63--82},
publisher = {Elsevier},
abstract = {The ignition of combustible materials is an important aspect of the processes taking place in an unwanted fire. In this work, an experimental and theoretical study of the ignition process of wood has been carried out. Experiments of both spontaneous and piloted ignition have been performed. Constant and decreasing variable heat fluxes have been tested. A mathematical model has been used to predict the time to ignition of wood for the different operating conditions used. The solution of the model provides the temperature at each point of the solid, the local solid conversion and the time to ignition of the material. In general, a good agreement between experimental and theoretical results is obtained. textcopyright 2002 Elsevier Science B.V. All rights reserved.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The ignition of combustible materials is an important aspect of the processes taking place in an unwanted fire. In this work, an experimental and theoretical study of the ignition process of wood has been carried out. Experiments of both spontaneous and piloted ignition have been performed. Constant and decreasing variable heat fluxes have been tested. A mathematical model has been used to predict the time to ignition of wood for the different operating conditions used. The solution of the model provides the temperature at each point of the solid, the local solid conversion and the time to ignition of the material. In general, a good agreement between experimental and theoretical results is obtained. textcopyright 2002 Elsevier Science B.V. All rights reserved.
Alzueta, María U; Hernández, J M
Ethanol oxidation and its interaction with nitric oxide Journal Article
In: Energy and Fuels, vol. 16, no. 1, pp. 166–171, 2002, ISSN: 08870624.
@article{Alzueta2002b,
title = {Ethanol oxidation and its interaction with nitric oxide},
author = {María U Alzueta and J M Hernández},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef010153n},
issn = {08870624},
year = {2002},
date = {2002-01-01},
journal = {Energy and Fuels},
volume = {16},
number = {1},
pages = {166--171},
publisher = {American Chemical Society},
abstract = {An experimental and theoretical study of the oxidation of ethanol in absence and in the presence of NO has been performed. The experiments were conducted in an isothermal quartz flow reactor at atmospheric pressure in the 700-1500 K temperature range. The influence of the temperature, oxygen concentration, and presence of NO on the concentrations of ethanol, CO, CO2, and NO has been analyzed. A reaction mechanism based on the model of Glarborg et al.1 for hydrocarbon/NO interactions, the mechanism for methanol oxidation2, updated in relation to the ethanol reaction subset, mainly with reactions taken from Marinov3, has been used for calculations. The results show that the oxidation regime of ethanol for different air excess conditions is very similar in the absence and presence of NO, even though differences can be seen. In general, as the stoichiometry becomes leaner, the oxidation of ethanol is produced at lower temperatures, with little differences between rich and close to stoichiometric conditions. The presence of NO results in higher differences of the oxidation regimes of ethanol, in the way that NO inhibits ethanol conversion for the richest conditions, while it promotes ethanol oxidation for very lean conditions. The experimental results are analyzed in terms of detailed chemistry and the main issues are discussed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An experimental and theoretical study of the oxidation of ethanol in absence and in the presence of NO has been performed. The experiments were conducted in an isothermal quartz flow reactor at atmospheric pressure in the 700-1500 K temperature range. The influence of the temperature, oxygen concentration, and presence of NO on the concentrations of ethanol, CO, CO2, and NO has been analyzed. A reaction mechanism based on the model of Glarborg et al.1 for hydrocarbon/NO interactions, the mechanism for methanol oxidation2, updated in relation to the ethanol reaction subset, mainly with reactions taken from Marinov3, has been used for calculations. The results show that the oxidation regime of ethanol for different air excess conditions is very similar in the absence and presence of NO, even though differences can be seen. In general, as the stoichiometry becomes leaner, the oxidation of ethanol is produced at lower temperatures, with little differences between rich and close to stoichiometric conditions. The presence of NO results in higher differences of the oxidation regimes of ethanol, in the way that NO inhibits ethanol conversion for the richest conditions, while it promotes ethanol oxidation for very lean conditions. The experimental results are analyzed in terms of detailed chemistry and the main issues are discussed.
2001
Journal Articles
Alzueta, María U; Bilbao, Rafael; Glarborg, Peter
Inhibition and sensitization of fuel oxidation by SO2 Journal Article
In: Combustion and Flame, vol. 127, no. 4, pp. 2234–2251, 2001, ISSN: 00102180.
@article{Alzueta2001a,
title = {Inhibition and sensitization of fuel oxidation by SO2},
author = {María U Alzueta and Rafael Bilbao and Peter Glarborg},
doi = {10.1016/S0010-2180(01)00325-X},
issn = {00102180},
year = {2001},
date = {2001-12-01},
journal = {Combustion and Flame},
volume = {127},
number = {4},
pages = {2234--2251},
publisher = {Elsevier Inc.},
abstract = {An experimental and theoretical study of the interaction of SO2 with the radical pool under combustion conditions has been carried out. Experiments on moist CO oxidation were conducted in an isothermal quartz flow reactor at 1 atm; temperature ranged from 800 to 1,500 K and stoichiometries from fuel-rich to very lean. In addition, literature data on sulfur species concentration profiles and H atom decay in fuel-rich H2/O2 flames doped with SO2 were analyzed. The results show that under flow-reactor conditions SO2 may inhibit or promote oxidation of fuel, depending on conditions. In a narrow range of operating conditions close to stoichiometric SO2 promotes oxidation through the sequence: SO2 + H ⇌ SO + OH, SO + O2 ⇌ SO2 + O. Inhibition of oxidation by removal of radicals can be explained in terms of the SO2+O+M reaction, even under fuel-rich conditions. From the shift in temperature for the onset of CO oxidation because of SO2 addition under reducing conditions an upper limit of 3.0 × 1014 cm6 mol-2s-1 at 1,060 K can be estimated for the rate constant of H + SO2 + N2 ⇌ HOSO + N2. This value is consistent with a significant barrier to reaction as proposed theoretically, but an order of magnitude lower than indicated by both ab initio calculations (Marshall and co-workers) and reaction rates derived from flames. However, we find that data on H atom decay in flames doped with SO2 are not suitable for deriving rate constants because of uncertainty in important side reactions involving SO. Furthermore, we propose that the enhanced H atom decay observed in these flames may be attributed to recombination of H atoms with SO and S2 species, rather than to a mechanism initiated by the H + SO2 + M reaction. textcopyright 2001 by The Combustion Institute.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An experimental and theoretical study of the interaction of SO2 with the radical pool under combustion conditions has been carried out. Experiments on moist CO oxidation were conducted in an isothermal quartz flow reactor at 1 atm; temperature ranged from 800 to 1,500 K and stoichiometries from fuel-rich to very lean. In addition, literature data on sulfur species concentration profiles and H atom decay in fuel-rich H2/O2 flames doped with SO2 were analyzed. The results show that under flow-reactor conditions SO2 may inhibit or promote oxidation of fuel, depending on conditions. In a narrow range of operating conditions close to stoichiometric SO2 promotes oxidation through the sequence: SO2 + H ⇌ SO + OH, SO + O2 ⇌ SO2 + O. Inhibition of oxidation by removal of radicals can be explained in terms of the SO2+O+M reaction, even under fuel-rich conditions. From the shift in temperature for the onset of CO oxidation because of SO2 addition under reducing conditions an upper limit of 3.0 × 1014 cm6 mol-2s-1 at 1,060 K can be estimated for the rate constant of H + SO2 + N2 ⇌ HOSO + N2. This value is consistent with a significant barrier to reaction as proposed theoretically, but an order of magnitude lower than indicated by both ab initio calculations (Marshall and co-workers) and reaction rates derived from flames. However, we find that data on H atom decay in flames doped with SO2 are not suitable for deriving rate constants because of uncertainty in important side reactions involving SO. Furthermore, we propose that the enhanced H atom decay observed in these flames may be attributed to recombination of H atoms with SO and S2 species, rather than to a mechanism initiated by the H + SO2 + M reaction. textcopyright 2001 by The Combustion Institute.