2001
Journal Articles
Bilbao, Rafael; Mastral, José Francisco; Aldea, María E; Ceamanos, Jesús; Betrán, Mónica; Lana, José A
Experimental and theoretical study of the ignition and smoldering of wood including convective effects Journal Article
In: Combustion and Flame, vol. 126, no. 1-2, pp. 1363–1372, 2001, ISSN: 00102180.
@article{Bilbao2001,
title = {Experimental and theoretical study of the ignition and smoldering of wood including convective effects},
author = {Rafael Bilbao and José Francisco Mastral and María E Aldea and Jesús Ceamanos and Mónica Betrán and José A Lana},
doi = {10.1016/S0010-2180(01)00251-6},
issn = {00102180},
year = {2001},
date = {2001-07-01},
journal = {Combustion and Flame},
volume = {126},
number = {1-2},
pages = {1363--1372},
publisher = {Elsevier},
abstract = {Ignition, as one of the most important processes during the initiation and development of a fire, needs to be studied in different situations. In this work, an experimental and theoretical study of the ignition of wood, including convective effects, has been performed. The experimental study includes tests of both spontaneous and piloted ignition with air flows at different velocities over the sample. Depending on the conditions, smoldering was observed, followed either by ignition or extinction. In some cases, decomposition of the sample occurred without the appearance of a flame. A mathematical model has been used that includes the kinetics of thermal decomposition of wood, the latent heat of vaporization of water, and variable thermal properties. The model provided the temperature at each point in the solid, the local conversion of solid, the time to smoldering, and the time to ignition of the material. In general, reasonable agreement between experimental and theoretical results was obtained. Copyright textcopyright 2001 Elsevier Science Inc.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Ignition, as one of the most important processes during the initiation and development of a fire, needs to be studied in different situations. In this work, an experimental and theoretical study of the ignition of wood, including convective effects, has been performed. The experimental study includes tests of both spontaneous and piloted ignition with air flows at different velocities over the sample. Depending on the conditions, smoldering was observed, followed either by ignition or extinction. In some cases, decomposition of the sample occurred without the appearance of a flame. A mathematical model has been used that includes the kinetics of thermal decomposition of wood, the latent heat of vaporization of water, and variable thermal properties. The model provided the temperature at each point in the solid, the local conversion of solid, the time to smoldering, and the time to ignition of the material. In general, reasonable agreement between experimental and theoretical results was obtained. Copyright textcopyright 2001 Elsevier Science Inc.
Alzueta, María U; Bilbao, Rafael; Finestra, M
Methanol oxidation and its interaction with nitric oxide Journal Article
In: Energy and Fuels, vol. 15, no. 3, pp. 724–729, 2001, ISSN: 08870624.
@article{Alzueta2001,
title = {Methanol oxidation and its interaction with nitric oxide},
author = {María U Alzueta and Rafael Bilbao and M Finestra},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef0002602},
issn = {08870624},
year = {2001},
date = {2001-05-01},
journal = {Energy and Fuels},
volume = {15},
number = {3},
pages = {724--729},
publisher = {American Chemical Society},
abstract = {An experimental and theoretical study of the oxidation of methanol 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 the temperature, oxygen concentration, and presence of NO on the concentrations of methanol, CO, CO2, and NO has been analyzed. A reaction mechanism based on the model of Glarborg et al. for hydrocarbons/NO interactions, updated in relation to the methanol reaction subset has been used for calculations. The results show that the oxidation regime of methanol for different air excess conditions is very Similar in the absence of NO, but significant differences are observed when NO is present. The presence of NO implies a different behaviour depending on the stoichiometry, in the way that such presence results in a inhibition of methanol conversion for richest conditions, while it promotes methanol 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 methanol 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 the temperature, oxygen concentration, and presence of NO on the concentrations of methanol, CO, CO2, and NO has been analyzed. A reaction mechanism based on the model of Glarborg et al. for hydrocarbons/NO interactions, updated in relation to the methanol reaction subset has been used for calculations. The results show that the oxidation regime of methanol for different air excess conditions is very Similar in the absence of NO, but significant differences are observed when NO is present. The presence of NO implies a different behaviour depending on the stoichiometry, in the way that such presence results in a inhibition of methanol conversion for richest conditions, while it promotes methanol oxidation for very lean conditions. The experimental results are analyzed in terms of detailed chemistry and the main issues are discussed.
García, Lucía; Salvador, María L; Arauzo, Jesús; Bilbao, Rafael
Catalytic pyrolysis of biomass: Influence of the catalyst pretreatment on gas yields Journal Article
In: Journal of Analytical and Applied Pyrolysis, vol. 58-59, pp. 491–501, 2001, ISSN: 01652370.
@article{Garcia2001,
title = {Catalytic pyrolysis of biomass: Influence of the catalyst pretreatment on gas yields},
author = {Lucía García and María L Salvador and Jesús Arauzo and Rafael Bilbao},
doi = {10.1016/S0165-2370(00)00114-5},
issn = {01652370},
year = {2001},
date = {2001-04-01},
journal = {Journal of Analytical and Applied Pyrolysis},
volume = {58-59},
pages = {491--501},
publisher = {Elsevier},
abstract = {This experimental study of biomass catalytic pyrolysis at low temperatures (650 and 700°C) was carried out in an installation based on the Waterloo Fast Pyrolysis Process (WFPP) technology, with a Ni/Al coprecipitated catalyst introduced into the reaction bed where the thermochemical decomposition of biomass took place. The influence of the calcination temperature (750-850°C) and the activation conditions (hydrogen flow rate) of the catalyst were analyzed. The calcination temperature significantly influences the properties and performance of the catalyst. For the two reaction temperatures, 650 and 700°C, and with the catalyst calcined at 850°C, higher H2 and CO yields were obtained with the reduced catalyst (flow rate 3080 cm3 (STP)/min; WHSV = 0.826 h-1) than without reduction. However, the catalyst calcined at 750°C without reduction showed a good performance at the reaction temperature of 700°C. Considering the characterization and experimental results, it can be deduced that the catalyst calcined at 750°C is reduced by the reaction atmosphere forming a stable active phase, whereas for the catalyst calcined at 850°C more severe reduction conditions are necessary. textcopyright 2001 Elsevier Science B.V.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
This experimental study of biomass catalytic pyrolysis at low temperatures (650 and 700°C) was carried out in an installation based on the Waterloo Fast Pyrolysis Process (WFPP) technology, with a Ni/Al coprecipitated catalyst introduced into the reaction bed where the thermochemical decomposition of biomass took place. The influence of the calcination temperature (750-850°C) and the activation conditions (hydrogen flow rate) of the catalyst were analyzed. The calcination temperature significantly influences the properties and performance of the catalyst. For the two reaction temperatures, 650 and 700°C, and with the catalyst calcined at 850°C, higher H2 and CO yields were obtained with the reduced catalyst (flow rate 3080 cm3 (STP)/min; WHSV = 0.826 h-1) than without reduction. However, the catalyst calcined at 750°C without reduction showed a good performance at the reaction temperature of 700°C. Considering the characterization and experimental results, it can be deduced that the catalyst calcined at 750°C is reduced by the reaction atmosphere forming a stable active phase, whereas for the catalyst calcined at 850°C more severe reduction conditions are necessary. textcopyright 2001 Elsevier Science B.V.
Puértolas, Rosa; Gea, Gloria; Murillo, María Benita; Arauzo, Jesús
Pyrolysis of black liquors from alkaline pulping of straw. Influence of a preoxidation stage on the char characteristics Journal Article
In: Journal of Analytical and Applied Pyrolysis, vol. 58-59, pp. 955–966, 2001, ISSN: 01652370.
@article{Puertolas2001,
title = {Pyrolysis of black liquors from alkaline pulping of straw. Influence of a preoxidation stage on the char characteristics},
author = {Rosa Puértolas and Gloria Gea and María Benita Murillo and Jesús Arauzo},
doi = {10.1016/S0165-2370(00)00175-3},
issn = {01652370},
year = {2001},
date = {2001-04-01},
journal = {Journal of Analytical and Applied Pyrolysis},
volume = {58-59},
pages = {955--966},
publisher = {Elsevier},
abstract = {New alternative processes such as low temperature gasification are currently being developed in order to use of black liquors from pulp and paper mills with energy proposes. The development of these new processes makes necessary to study the behavior of black liquors during pyrolysis and gasification paying special attention on their thermoplastic properties, which can cause important operational problems due to its swelling when heated. Present work is focused to the study of pyrolysis of alkaline black liquors from pulping of straw. The influence of an oxidation stage at low temperature previous to pyrolysis, on specific surface area of the char and on the black liquor swelling, is studied. For that, two main variables are analyzed: time of preoxidation and final temperature of pyrolysis. Dry black liquors from alkaline pulping of straw were used as material. The resulting chars obtained showed a clear decrease in swelling level of the black liquors, as well as an increase on their specific surface area, within the pyrolysis temperature and the preoxidation time. Materials with specific surface areas varying from 2 up to nearly 500 m2 g-1 can be produced with the correct choice of experimental conditions. From the results, further research on the influence of a preoxidation stage on black liquors may lead to a better understanding of new alternative processes, which are nowadays being developed. textcopyright 2001 Elsevier Science B.V.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
New alternative processes such as low temperature gasification are currently being developed in order to use of black liquors from pulp and paper mills with energy proposes. The development of these new processes makes necessary to study the behavior of black liquors during pyrolysis and gasification paying special attention on their thermoplastic properties, which can cause important operational problems due to its swelling when heated. Present work is focused to the study of pyrolysis of alkaline black liquors from pulping of straw. The influence of an oxidation stage at low temperature previous to pyrolysis, on specific surface area of the char and on the black liquor swelling, is studied. For that, two main variables are analyzed: time of preoxidation and final temperature of pyrolysis. Dry black liquors from alkaline pulping of straw were used as material. The resulting chars obtained showed a clear decrease in swelling level of the black liquors, as well as an increase on their specific surface area, within the pyrolysis temperature and the preoxidation time. Materials with specific surface areas varying from 2 up to nearly 500 m2 g-1 can be produced with the correct choice of experimental conditions. From the results, further research on the influence of a preoxidation stage on black liquors may lead to a better understanding of new alternative processes, which are nowadays being developed. textcopyright 2001 Elsevier Science B.V.
García, Lucía; Salvador, María L; Arauzo, Jesús; Bilbao, Rafael
CO2 as a gasifying agent for gas production from pine sawdust at low temperatures using a Ni/Al coprecipitated catalyst Journal Article
In: Fuel processing technology, vol. 69, no. 2, pp. 157–174, 2001, ISSN: 03783820.
@article{Garcia2001a,
title = {CO2 as a gasifying agent for gas production from pine sawdust at low temperatures using a Ni/Al coprecipitated catalyst},
author = {Lucía García and María L Salvador and Jesús Arauzo and Rafael Bilbao},
doi = {10.1016/S0378-3820(00)00138-7},
issn = {03783820},
year = {2001},
date = {2001-02-01},
journal = {Fuel processing technology},
volume = {69},
number = {2},
pages = {157--174},
publisher = {Elsevier Science Publishers B.V.},
abstract = {Catalytic CO2 gasification of pine sawdust has been carried out at a relatively low temperature, 700 °C, and at atmospheric pressure. The Ni/Al catalyst used was prepared by coprecipitation and calcined at 750 °C for 3 h. The influence of the catalyst weight/biomass flow rate (W/mb) ratio on product distribution and gas composition was analyzed. Using a CO2/biomass ratio of around 1, the increase of the W/mb ratio increases H2 and CO yields while CH4 and C2 yields decrease. Deactivation of the catalyst was also observed under the experimental conditions employed. The influence of the W/mb ratio on the initial gas yields has been also analyzed. For W/mb ratios ≥0.3 h, no significant modifications are observed on the initial yields of different gases, and it is confirmed that under these conditions the initial gas composition is close to that for thermodynamic equilibrium. The influence of the reaction atmosphere on gas yields has also been carried out, analyzing the results obtained in pyrolysis, steam gasification and CO2 gasification.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Catalytic CO2 gasification of pine sawdust has been carried out at a relatively low temperature, 700 °C, and at atmospheric pressure. The Ni/Al catalyst used was prepared by coprecipitation and calcined at 750 °C for 3 h. The influence of the catalyst weight/biomass flow rate (W/mb) ratio on product distribution and gas composition was analyzed. Using a CO2/biomass ratio of around 1, the increase of the W/mb ratio increases H2 and CO yields while CH4 and C2 yields decrease. Deactivation of the catalyst was also observed under the experimental conditions employed. The influence of the W/mb ratio on the initial gas yields has been also analyzed. For W/mb ratios ≥0.3 h, no significant modifications are observed on the initial yields of different gases, and it is confirmed that under these conditions the initial gas composition is close to that for thermodynamic equilibrium. The influence of the reaction atmosphere on gas yields has also been carried out, analyzing the results obtained in pyrolysis, steam gasification and CO2 gasification.
Lumbreras, M; Alzueta, María U; Millera, Ángela; Bilbao, Rafael
A study of pyrrole oxidation under flow reactor conditions Journal Article
In: Combustion Science and Technology, vol. 172, no. 1, pp. 123–139, 2001, ISSN: 00102202.
@article{Lumbreras2001,
title = {A study of pyrrole oxidation under flow reactor conditions},
author = {M Lumbreras and María U Alzueta and Ángela Millera and Rafael Bilbao},
url = {https://www.tandfonline.com/doi/abs/10.1080/00102200108945397},
doi = {10.1080/00102200108945397},
issn = {00102202},
year = {2001},
date = {2001-01-01},
journal = {Combustion Science and Technology},
volume = {172},
number = {1},
pages = {123--139},
publisher = {Taylor and Francis Inc.},
abstract = {An experimental study of the oxidation of pyrrole 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 the temperature, air excess ratio (corresponding to rich, stoichiometric, and lean conditions), and presence of NO on the concentrations of CO, CO2, HCN, and NO has been analyzed. The present work, which corresponds to the global objective of studying the conversion of volatile nitrogen compounds, contributes to it with results related to pyrrole that contribute to extend the experimental database on the conversion of nitrogen volatile compounds. Also, a preliminary 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 pyrrole 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 the temperature, air excess ratio (corresponding to rich, stoichiometric, and lean conditions), and presence of NO on the concentrations of CO, CO2, HCN, and NO has been analyzed. The present work, which corresponds to the global objective of studying the conversion of volatile nitrogen compounds, contributes to it with results related to pyrrole that contribute to extend the experimental database on the conversion of nitrogen volatile compounds. Also, a preliminary reaction mechanism based on various literature mechanisms has been used for simulating the experimental results.
2000
Journal Articles
Oliva, Miriam; Alzueta, María U; Millera, Ángela; Bilbao, Rafael
Theoretical study of the influence of mixing in the SNCR process. Comparison with pilot scale data Journal Article
In: Chemical Engineering Science, vol. 55, no. 22, pp. 5321–5332, 2000, ISSN: 00092509.
@article{Oliva2000,
title = {Theoretical study of the influence of mixing in the SNCR process. Comparison with pilot scale data},
author = {Miriam Oliva and María U Alzueta and Ángela Millera and Rafael Bilbao},
doi = {10.1016/S0009-2509(00)00149-4},
issn = {00092509},
year = {2000},
date = {2000-11-01},
journal = {Chemical Engineering Science},
volume = {55},
number = {22},
pages = {5321--5332},
publisher = {Elsevier Science Ltd},
abstract = {A theoretical study of the influence of mixing on the selective non-catalytic reduction (SNCR) process has been performed. The study includes the use of a detailed kinetic reaction mechanism together with a simple approach for mixing based on the `maximum mixedness model' proposed by Zwietering (1959). Two different configurations for that simple mixing approach have been considered and discussed, i.e. the `direct approach' which implies entrainment of the jet flow (containing the SNCR reduction agent) into a bulk flow (containing the products of the main combustion zone); and the `reverse approach' which represents entrainment of the bulk flow into the jet stream. The main features of both approaches applied to the SNCR process are analyzed and discussed. Furthermore, comparison of the results obtained with the present approaches with different experimental pilot scale results is performed.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A theoretical study of the influence of mixing on the selective non-catalytic reduction (SNCR) process has been performed. The study includes the use of a detailed kinetic reaction mechanism together with a simple approach for mixing based on the `maximum mixedness model’ proposed by Zwietering (1959). Two different configurations for that simple mixing approach have been considered and discussed, i.e. the `direct approach’ which implies entrainment of the jet flow (containing the SNCR reduction agent) into a bulk flow (containing the products of the main combustion zone); and the `reverse approach’ which represents entrainment of the bulk flow into the jet stream. The main features of both approaches applied to the SNCR process are analyzed and discussed. Furthermore, comparison of the results obtained with the present approaches with different experimental pilot scale results is performed.
Glarborg, Peter; Kristensen, Per G; Dam-Johansen, Kim; Alzueta, María U; Millera, Ángela; Bilbao, Rafael
Nitric oxide reduction by non-hydrocarbon fuels. Implications for reburning with gasification gases Journal Article
In: Energy and Fuels, vol. 14, no. 4, pp. 828–838, 2000, ISSN: 08870624.
@article{Glarborg2000,
title = {Nitric oxide reduction by non-hydrocarbon fuels. Implications for reburning with gasification gases},
author = {Peter Glarborg and Per G Kristensen and Kim Dam-Johansen and María U Alzueta and Ángela Millera and Rafael Bilbao},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef990186r},
issn = {08870624},
year = {2000},
date = {2000-07-01},
journal = {Energy and Fuels},
volume = {14},
number = {4},
pages = {828--838},
publisher = {ACS},
abstract = {The ability of non-hydrocarbon fuels such as CO and H2 to reduce nitric oxide under conditions relevant for the reburning process is investigated experimentally and theoretically. Flow reactor experiments on reduction of NO by CO and H2 are conducted under fuel-rich conditions, covering temperatures of 1200-1800 K and a range of stoichiometries and reactant levels. Bench and pilot scale results from literature on reburning with CO, H2, and low calorific value gases are also considered. The experimental data are interpreted in terms of a detailed reaction mechanism, and the reactions responsible for removal of NO are identified. The experimental results indicate that under typical reburn process conditions these non-hydrocarbon fuels may remove 20-30% of the nitric oxide entering the reburn zone. However, results indicate that the process potential increases with temperature and reburn fuel fraction, and at high temperatures and reburn fuel fractions of about 30%, the reduction efficiency approaches that of hydrocarbon gases. If dilution effects and the lowering of the primary zone NO (maintaining the overall load) are accounted for, the reduction potential is further increased. Modeling results indicate that the mixing process may affect the NO reduction in the reducing zone. The modeling predictions are in qualitative agreement with the experimental results but tend to underestimate the reduction of NO. Conversion of NO to N2 in the reburn zone proceeds primarily through the following sequence: H+NO+M⇔HNO+M, HNO+H⇔NH+OH, NH+NO→N2+... The implications of the results for reburning with fuels with a low hydrocarbon content are discussed, with special emphasis on gasified fuels.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The ability of non-hydrocarbon fuels such as CO and H2 to reduce nitric oxide under conditions relevant for the reburning process is investigated experimentally and theoretically. Flow reactor experiments on reduction of NO by CO and H2 are conducted under fuel-rich conditions, covering temperatures of 1200-1800 K and a range of stoichiometries and reactant levels. Bench and pilot scale results from literature on reburning with CO, H2, and low calorific value gases are also considered. The experimental data are interpreted in terms of a detailed reaction mechanism, and the reactions responsible for removal of NO are identified. The experimental results indicate that under typical reburn process conditions these non-hydrocarbon fuels may remove 20-30% of the nitric oxide entering the reburn zone. However, results indicate that the process potential increases with temperature and reburn fuel fraction, and at high temperatures and reburn fuel fractions of about 30%, the reduction efficiency approaches that of hydrocarbon gases. If dilution effects and the lowering of the primary zone NO (maintaining the overall load) are accounted for, the reduction potential is further increased. Modeling results indicate that the mixing process may affect the NO reduction in the reducing zone. The modeling predictions are in qualitative agreement with the experimental results but tend to underestimate the reduction of NO. Conversion of NO to N2 in the reburn zone proceeds primarily through the following sequence: H+NO+M⇔HNO+M, HNO+H⇔NH+OH, NH+NO→N2+… The implications of the results for reburning with fuels with a low hydrocarbon content are discussed, with special emphasis on gasified fuels.
Muñoz, Mariano; Moreno, Francisco; Morea-Roy, J; Ruiz, Joaquín; Arauzo, Jesús
Low heating value gas on spark ignition engines Journal Article
In: Biomass and Bioenergy, vol. 18, no. 5, pp. 431–439, 2000, ISSN: 09619534.
@article{Munoz2000,
title = {Low heating value gas on spark ignition engines},
author = {Mariano Muñoz and Francisco Moreno and J Morea-Roy and Joaquín Ruiz and Jesús Arauzo},
doi = {10.1016/S0961-9534(99)00101-4},
issn = {09619534},
year = {2000},
date = {2000-05-01},
journal = {Biomass and Bioenergy},
volume = {18},
number = {5},
pages = {431--439},
publisher = {Elsevier Science Ltd},
abstract = {The performance of a spark ignition engine using low heating value (LHV) gas generated in a fixed bed downdraft (co-current) gasifier, using agricultural and forestry residues was measured on a dynamometer test bench. The parameters measured include torque, power output, emissions measurement, exhaust gas temperature for both operation on gasoline and LHV gas. Improvements in hydrocarbon and carbon monoxide emissions were obtained and the engine suffered less thermal stress under LHV gas operation. The power loss was relatively low, though the experimental arrangement restricted the power output at high throughputs of gas. (C) 2000 Elsevier Science Ltd.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The performance of a spark ignition engine using low heating value (LHV) gas generated in a fixed bed downdraft (co-current) gasifier, using agricultural and forestry residues was measured on a dynamometer test bench. The parameters measured include torque, power output, emissions measurement, exhaust gas temperature for both operation on gasoline and LHV gas. Improvements in hydrocarbon and carbon monoxide emissions were obtained and the engine suffered less thermal stress under LHV gas operation. The power loss was relatively low, though the experimental arrangement restricted the power output at high throughputs of gas. (C) 2000 Elsevier Science Ltd.
Alzueta, María U; Bilbao, Rafael; Millera, Ángela; Oliva, Miriam; Ibañez, J C
Impact of new findings concerning urea thermal decomposition on the modeling of the urea-SNCR process Journal Article
In: Energy and Fuels, vol. 14, no. 2, pp. 509–510, 2000, ISSN: 08870624.
@article{Alzueta2000,
title = {Impact of new findings concerning urea thermal decomposition on the modeling of the urea-SNCR process},
author = {María U Alzueta and Rafael Bilbao and Ángela Millera and Miriam Oliva and J C Ibañez},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef990187j},
issn = {08870624},
year = {2000},
date = {2000-01-01},
journal = {Energy and Fuels},
volume = {14},
number = {2},
pages = {509--510},
publisher = {American Chemical Society},
abstract = {The interest in selective non-catalytic reduction (SNCR) applications has motivated the study of a number of possible configurations for NO x reduction. Among those, the use of urea as selective non-catalytic agent appears to be interesting. 1,2 Urea seems to be suitable because of handling and storage reasons, compared to other selective NO x reduction agents such as ammonia. A number of investigations have been carried out concerning the use of urea in the SNCR process during the past years, both experimentally on different scales, 2-4 and from a kinetic modeling point of view. 3,5 While the effectiveness in the process is well demonstrated experimentally through the different investigations, the kinetic modeling of the process presented some uncertainties mainly due to the behavior of urea under high temperature conditions. Urea has been traditionally considered to be decomposed into NH 3 and HNCO at high temperatures, 6,7 even though other decomposition paths have been proposed. 5,8 The agreement between experiments and calculations using those different mechanisms for urea decomposition is reasonably good, but a reliable determination of urea thermal decomposition was needed. Recent experimental results have appeared concerning the measurement of the reaction rate for the thermal urea decomposition reaction under conditions applicable to SNCR conditions. 9 In this communication, we want to show the impact of the new recent results by Aoki et al. 9 in the modeling of the SNCR process using urea. Aoki et al. 9 determined the reaction rate and products distribution of the thermal decomposition of urea. They obtained the following rates and product channels for the decomposition of urea at high temperatures when it is fed as an aqueous solution: We have included those reactions in the mechanism we used previously for studying the urea-SNCR process, 3 and the results are in good agreement with the previous Figure 1. Experimental and calculated results of NO and N2O concentrations vs temperature. Solid lines: calculations made assuming ideal mixing. Dashed lines: calculations made assuming a mixing time of 10 ms. (Inlet concentrations: 100 ppm NO, 150 ppm urea, 4% O2, 4% H2O, N2 to balance). Residence time(s)) 200/T(K). (NH 2) 2 CO f NH 3 + HNCO k 1) 1.2676 × 10 4 exp(-15540/[cal/mol]RT) (NH 2) 2 CO + H 2 O f 2 NH 3 + CO 2 k 2) 9.925 × 10 3 exp(-20980/[cal/mol]RT) 509},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The interest in selective non-catalytic reduction (SNCR) applications has motivated the study of a number of possible configurations for NO x reduction. Among those, the use of urea as selective non-catalytic agent appears to be interesting. 1,2 Urea seems to be suitable because of handling and storage reasons, compared to other selective NO x reduction agents such as ammonia. A number of investigations have been carried out concerning the use of urea in the SNCR process during the past years, both experimentally on different scales, 2-4 and from a kinetic modeling point of view. 3,5 While the effectiveness in the process is well demonstrated experimentally through the different investigations, the kinetic modeling of the process presented some uncertainties mainly due to the behavior of urea under high temperature conditions. Urea has been traditionally considered to be decomposed into NH 3 and HNCO at high temperatures, 6,7 even though other decomposition paths have been proposed. 5,8 The agreement between experiments and calculations using those different mechanisms for urea decomposition is reasonably good, but a reliable determination of urea thermal decomposition was needed. Recent experimental results have appeared concerning the measurement of the reaction rate for the thermal urea decomposition reaction under conditions applicable to SNCR conditions. 9 In this communication, we want to show the impact of the new recent results by Aoki et al. 9 in the modeling of the SNCR process using urea. Aoki et al. 9 determined the reaction rate and products distribution of the thermal decomposition of urea. They obtained the following rates and product channels for the decomposition of urea at high temperatures when it is fed as an aqueous solution: We have included those reactions in the mechanism we used previously for studying the urea-SNCR process, 3 and the results are in good agreement with the previous Figure 1. Experimental and calculated results of NO and N2O concentrations vs temperature. Solid lines: calculations made assuming ideal mixing. Dashed lines: calculations made assuming a mixing time of 10 ms. (Inlet concentrations: 100 ppm NO, 150 ppm urea, 4% O2, 4% H2O, N2 to balance). Residence time(s)) 200/T(K). (NH 2) 2 CO f NH 3 + HNCO k 1) 1.2676 × 10 4 exp(-15540/[cal/mol]RT) (NH 2) 2 CO + H 2 O f 2 NH 3 + CO 2 k 2) 9.925 × 10 3 exp(-20980/[cal/mol]RT) 509
Alzueta, María U; Glarborg, Peter; Dam-Johansen, Kim
Experimental and kinetic modeling study of the oxidation of benzene Journal Article
In: International Journal of Chemical Kinetics, vol. 32, no. 8, pp. 498–522, 2000, ISSN: 05388066.
@article{Alzueta2000b,
title = {Experimental and kinetic modeling study of the oxidation of benzene},
author = {María U Alzueta and Peter Glarborg and Kim Dam-Johansen},
url = {https://onlinelibrary.wiley.com/doi/full/10.1002/1097-4601%282000%2932%3A8%3C498%3A%3AAID-KIN8%3E3.0.CO%3B2-H https://onlinelibrary.wiley.com/doi/abs/10.1002/1097-4601%282000%2932%3A8%3C498%3A%3AAID-KIN8%3E3.0.CO%3B2-H https://onlinelibrary.wiley.com/doi/10.1002/1097-4601(2000)32:8%3C498::AID-KIN8%3E3.0.CO;2-H},
doi = {10.1002/1097-4601(2000)32:8<498::AID-KIN8>3.0.CO;2-H},
issn = {05388066},
year = {2000},
date = {2000-01-01},
journal = {International Journal of Chemical Kinetics},
volume = {32},
number = {8},
pages = {498--522},
publisher = {John Wiley & Sons Inc},
abstract = {The oxidation of benzene under flow-reactor conditions has been studied experimentally and in terms of a detailed chemical kinetic model. The experiments were performed under plug-flow conditions, at excess air ratios ranging from close to stoichiometric to very lean. The temperature range was 900-1450 K and the residence time of the order of 150 ms. The radical pool was perturbed by means of varying the concentration of water vapor and by adding NO. Furthermore, a few experiments were conducted on pyrolysis and oxidation of phenol. Benzene oxidation is initiated at approximately 1000 K; the temperature for complete oxidation depends on stoichiometry, ranging from 1100 K (very lean conditions) to 1300 K (close to stoichiometric). The water vapor level and the presence of NO have only a minor impact on the temperature regime for oxidation. The proposed chemical kinetic model was validated by comparison with the present experimental data as well as flow reactor and mixed reactor data from literature. The model provides a reasonably good description of the overall oxidation behavior of benzene over the range of conditions investigated. However, before details of the oxidation behavior can be predicted satisfactorily, a number of kinetic issues need to be resolved. These include product channels and rates for the reactions of phenyl and cyclopentadienyl with molecular oxygen as well as reaction chemistry for the oxygenated cyclic compounds formed as intermediates in the oxidation process.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The oxidation of benzene under flow-reactor conditions has been studied experimentally and in terms of a detailed chemical kinetic model. The experiments were performed under plug-flow conditions, at excess air ratios ranging from close to stoichiometric to very lean. The temperature range was 900-1450 K and the residence time of the order of 150 ms. The radical pool was perturbed by means of varying the concentration of water vapor and by adding NO. Furthermore, a few experiments were conducted on pyrolysis and oxidation of phenol. Benzene oxidation is initiated at approximately 1000 K; the temperature for complete oxidation depends on stoichiometry, ranging from 1100 K (very lean conditions) to 1300 K (close to stoichiometric). The water vapor level and the presence of NO have only a minor impact on the temperature regime for oxidation. The proposed chemical kinetic model was validated by comparison with the present experimental data as well as flow reactor and mixed reactor data from literature. The model provides a reasonably good description of the overall oxidation behavior of benzene over the range of conditions investigated. However, before details of the oxidation behavior can be predicted satisfactorily, a number of kinetic issues need to be resolved. These include product channels and rates for the reactions of phenyl and cyclopentadienyl with molecular oxygen as well as reaction chemistry for the oxygenated cyclic compounds formed as intermediates in the oxidation process.
1999
Journal Articles
Ruiz, Joaquín; Bilbao, Rafael; Murillo, María Benita
Convective transport and removal of vapors of two volatile compounds in sand columns under different air humidity conditions Journal Article
In: Environmental Science and Technology, vol. 33, no. 21, pp. 3774–3780, 1999, ISSN: 0013936X.
@article{Ruiz1999,
title = {Convective transport and removal of vapors of two volatile compounds in sand columns under different air humidity conditions},
author = {Joaquín Ruiz and Rafael Bilbao and María Benita Murillo},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/es9811344},
issn = {0013936X},
year = {1999},
date = {1999-11-01},
journal = {Environmental Science and Technology},
volume = {33},
number = {21},
pages = {3774--3780},
publisher = {ACS},
abstract = {The convective transport and removal of vapors of a polar compound (methyl ethyl ketone) and a nonpolar compound (n-octane) in quartz sand has been studied. A sharp front in the transport of the organic vapors through the sand and a tailing process in the removal of the compounds as a consequence of nonlinear adsorption have been observed. Due to the great influence that water vapor can have on the sorption of organic compounds onto soils, several experiments have been designed and carried out under different air humiditY and sand conditions. A competitive effect between the water and the organic molecules for the adsorption sites has been found as well as a substantial difference in behavior between the polar and the nonpolar compounds in the presence of water in the transport and in the removal of the organics from the sand. Simultaneously, a simple mathematical model has been developed to simulate the behavior of the two volatiles. This model takes into account the competitive sorption between organic and water molecules and considers that the adsorption takes place in equilibrium conditions, disregarding any kinetic effects. This model has been solved numerically and validated with the experimental results obtained, predicting quite accurately the behavior of the two organic compounds under very different conditions.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The convective transport and removal of vapors of a polar compound (methyl ethyl ketone) and a nonpolar compound (n-octane) in quartz sand has been studied. A sharp front in the transport of the organic vapors through the sand and a tailing process in the removal of the compounds as a consequence of nonlinear adsorption have been observed. Due to the great influence that water vapor can have on the sorption of organic compounds onto soils, several experiments have been designed and carried out under different air humiditY and sand conditions. A competitive effect between the water and the organic molecules for the adsorption sites has been found as well as a substantial difference in behavior between the polar and the nonpolar compounds in the presence of water in the transport and in the removal of the organics from the sand. Simultaneously, a simple mathematical model has been developed to simulate the behavior of the two volatiles. This model takes into account the competitive sorption between organic and water molecules and considers that the adsorption takes place in equilibrium conditions, disregarding any kinetic effects. This model has been solved numerically and validated with the experimental results obtained, predicting quite accurately the behavior of the two organic compounds under very different conditions.
García, Lucía; Salvador, María L; Arauzo, Jesús; Bilbao, Rafael
In: Energy and Fuels, vol. 13, no. 4, pp. 851–859, 1999, ISSN: 08870624.
@article{Garcia1999,
title = {Catalytic steam gasification of pine sawdust. Effect of catalyst weight/biomass flow rate and steam/biomass ratios on gas production and composition},
author = {Lucía García and María L Salvador and Jesús Arauzo and Rafael Bilbao},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef980250p},
issn = {08870624},
year = {1999},
date = {1999-07-01},
journal = {Energy and Fuels},
volume = {13},
number = {4},
pages = {851--859},
publisher = {ACS},
abstract = {Pine sawdust catalytic steam gasification has been studied in a fluidized bed at a relatively low temperature, 700 °C. The Ni-Al catalyst used was prepared by coprecipitation and calcined at 750 °C for 3 h. The influence of the catalyst weight/biomass flow rate (W/mb) and steam/biomass (S/B) ratios on the product distribution and on the quality of the gas product obtained was analyzed. An increase of the W/mb ratio increases the total gas, H2, CO, and CO2 yields, while CH4 and C2 yields decrease. An increase of the S/B ratio increases H2 and CO2 yields while CO and CH4 yields decrease. This fact can be explained by steam reforming and water-gas shift reactions. The increase of the S/B ratio also has a positive effect on the life of the catalyst. The gas composition and gas yields at initial time have also been studied. For W/mb ratios>0.5 h, the gas composition at initial time is similar to that for thermodynamic equilibrium for different S/B ratios. The influence of the S/B ratio on gas yield at initial time is more marked, up to a ratio of 1.5.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Pine sawdust catalytic steam gasification has been studied in a fluidized bed at a relatively low temperature, 700 °C. The Ni-Al catalyst used was prepared by coprecipitation and calcined at 750 °C for 3 h. The influence of the catalyst weight/biomass flow rate (W/mb) and steam/biomass (S/B) ratios on the product distribution and on the quality of the gas product obtained was analyzed. An increase of the W/mb ratio increases the total gas, H2, CO, and CO2 yields, while CH4 and C2 yields decrease. An increase of the S/B ratio increases H2 and CO2 yields while CO and CH4 yields decrease. This fact can be explained by steam reforming and water-gas shift reactions. The increase of the S/B ratio also has a positive effect on the life of the catalyst. The gas composition and gas yields at initial time have also been studied. For W/mb ratios>0.5 h, the gas composition at initial time is similar to that for thermodynamic equilibrium for different S/B ratios. The influence of the S/B ratio on gas yield at initial time is more marked, up to a ratio of 1.5.
Alzueta, María U; Muro, Julio; Bilbao, Rafael; Glarborg, Peter
Oxidation of Dimethyl Ether and its Interaction with Nitrogen Oxides Journal Article
In: Israel Journal of Chemistry, vol. 39, no. 1, pp. 73–86, 1999, ISSN: 00212148.
@article{Alzueta1999,
title = {Oxidation of Dimethyl Ether and its Interaction with Nitrogen Oxides},
author = {María U Alzueta and Julio Muro and Rafael Bilbao and Peter Glarborg},
url = {http://doi.wiley.com/10.1002/ijch.199900008},
doi = {10.1002/ijch.199900008},
issn = {00212148},
year = {1999},
date = {1999-01-01},
journal = {Israel Journal of Chemistry},
volume = {39},
number = {1},
pages = {73--86},
publisher = {Laser Pages Publishing Ltd.},
abstract = {The oxidation of dimethyl ether (DME) under flow reactor conditions has been studied experimentally and in terms of a detailed chemical kinetic model. The experiments were performed at atmospheric pressure in the temperature range 600-1500 K and at different air/fuel ratios. Of particular interest was the interaction of DME with nitrogen oxides. The results show that the oxidation of DME occurs readily at temperatures above 1000 K, largely independent of the stoichiometry. Addition of NO under stoichiometric and fuel-rich conditions does not affect the oxidation chemistry for DME, but above 1100 K a minor amount of the NO is reduced to HCN and N2 in reburn-type reactions. Addition of NO or NO2 under oxidizing conditions significantly enhances the oxidation rate of DME and shifts the temperature for onset of oxidation to lower values, a phenomenon similar to that of NOx-sensitized oxidation of hydrocarbons. The proposed chemical kinetic model provides a good description of DME oxidation in the absence of nitrogen oxides. Under the conditions of the present study, the conversion of DME proceeds mainly through the high-temperature mechanism, with little importance of the intermediate peroxy species. In the presence of NO or NO2, the reaction CH3 + NO2 ⇌ CH3O + NO, followed by dissociation of CH3O, readily provides H atoms and thereby promotes the oxidation. At lower temperatures the mechanism involves CH3OCH2O2 and CH3O2 radicals. While the effect of NOx generally is described satisfactorily by the model, deviations at lower temperatures may indicate inadequacies in the reaction subset for these peroxy species.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The oxidation of dimethyl ether (DME) under flow reactor conditions has been studied experimentally and in terms of a detailed chemical kinetic model. The experiments were performed at atmospheric pressure in the temperature range 600-1500 K and at different air/fuel ratios. Of particular interest was the interaction of DME with nitrogen oxides. The results show that the oxidation of DME occurs readily at temperatures above 1000 K, largely independent of the stoichiometry. Addition of NO under stoichiometric and fuel-rich conditions does not affect the oxidation chemistry for DME, but above 1100 K a minor amount of the NO is reduced to HCN and N2 in reburn-type reactions. Addition of NO or NO2 under oxidizing conditions significantly enhances the oxidation rate of DME and shifts the temperature for onset of oxidation to lower values, a phenomenon similar to that of NOx-sensitized oxidation of hydrocarbons. The proposed chemical kinetic model provides a good description of DME oxidation in the absence of nitrogen oxides. Under the conditions of the present study, the conversion of DME proceeds mainly through the high-temperature mechanism, with little importance of the intermediate peroxy species. In the presence of NO or NO2, the reaction CH3 + NO2 ⇌ CH3O + NO, followed by dissociation of CH3O, readily provides H atoms and thereby promotes the oxidation. At lower temperatures the mechanism involves CH3OCH2O2 and CH3O2 radicals. While the effect of NOx generally is described satisfactorily by the model, deviations at lower temperatures may indicate inadequacies in the reaction subset for these peroxy species.
1998
Journal Articles
Glarborg, Peter; Alzueta, María U; Dam-Johansen, Kim; Miller, James A
Kinetic modeling of hydrocarbon/nitric oxide interactions in a flow reactor Journal Article
In: Combustion and Flame, vol. 115, no. 1-2, pp. 1–27, 1998, ISSN: 00102180.
@article{Glarborg1998,
title = {Kinetic modeling of hydrocarbon/nitric oxide interactions in a flow reactor},
author = {Peter Glarborg and María U Alzueta and Kim Dam-Johansen and James A Miller},
doi = {10.1016/S0010-2180(97)00359-3},
issn = {00102180},
year = {1998},
date = {1998-10-01},
journal = {Combustion and Flame},
volume = {115},
number = {1-2},
pages = {1--27},
publisher = {Elsevier Inc.},
abstract = {The reduction of nitric oxide by reaction with C1 and C2 hydrocarbons under reducing conditions in a flow reactor has been analyzed in terms of a detailed chemical kinetic model. The experimental data were partly adopted from previous work and partly obtained in the present study; they cover the temperature range 800-1500 K and the reburn fuels CH4, C2H2, C2H4, C2H6, and natural gas. Modeling predictions indicate that, under the conditions investigated, HCCO + NO and CH3 + NO are the reactions most important in reducing NO. The HCCO + NO reaction is the dominant reaction when using natural gas or C2 hydrocarbons as reburn fuels. This reaction leads partly to HCNO, which is recycled to NO, and partly to HCN, which is converted to N2 or NO. When methane or natural gas are used as reburn fuel, the CH3 + NO reaction contributes significantly to remove NO. Modeling predictions are in reasonably good agreement with the experimental observations for the fuels investigated, even though the NO reduction potential is overpredicted for methane and underpredicted for ethane. Modeling predictions for NO are very sensitive to the formation of HCCO and to the product branching ratio for the HCCO + NO reaction. Furthermore, the present analysis indicates that more work is needed on critical steps in the hydrocarbon oxidation scheme.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The reduction of nitric oxide by reaction with C1 and C2 hydrocarbons under reducing conditions in a flow reactor has been analyzed in terms of a detailed chemical kinetic model. The experimental data were partly adopted from previous work and partly obtained in the present study; they cover the temperature range 800-1500 K and the reburn fuels CH4, C2H2, C2H4, C2H6, and natural gas. Modeling predictions indicate that, under the conditions investigated, HCCO + NO and CH3 + NO are the reactions most important in reducing NO. The HCCO + NO reaction is the dominant reaction when using natural gas or C2 hydrocarbons as reburn fuels. This reaction leads partly to HCNO, which is recycled to NO, and partly to HCN, which is converted to N2 or NO. When methane or natural gas are used as reburn fuel, the CH3 + NO reaction contributes significantly to remove NO. Modeling predictions are in reasonably good agreement with the experimental observations for the fuels investigated, even though the NO reduction potential is overpredicted for methane and underpredicted for ethane. Modeling predictions for NO are very sensitive to the formation of HCCO and to the product branching ratio for the HCCO + NO reaction. Furthermore, the present analysis indicates that more work is needed on critical steps in the hydrocarbon oxidation scheme.
Ruiz, Joaquín; Bilbao, Rafael; Murillo, María Benita
Adsorption of different VOC onto soil minerals from gas phase: Influence of mineral, type of VOC, and air humidity Journal Article
In: Environmental Science and Technology, vol. 32, no. 8, pp. 1079–1084, 1998, ISSN: 0013936X.
@article{Ruiz1998,
title = {Adsorption of different VOC onto soil minerals from gas phase: Influence of mineral, type of VOC, and air humidity},
author = {Joaquín Ruiz and Rafael Bilbao and María Benita Murillo},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/es9704996},
issn = {0013936X},
year = {1998},
date = {1998-04-01},
journal = {Environmental Science and Technology},
volume = {32},
number = {8},
pages = {1079--1084},
publisher = {ACS},
abstract = {The adsorption of volatile organic compounds (VOC) onto soils plays an important role in the mobility of these kinds of contaminant through soils. It is therefore of interest to learn more about the mechanisms of interaction between VOC and soil particles. An experimental study has been carried out in order to determine the adsorption isotherms of volatile organic gases of different properties on soil minerals of different characteristics, working in a wide range of compound concentrations. The adsorption of seven organic compounds concentrations. The adsorption of seven organic compounds (n- hexane, n-heptane, n-octane, toluene, xylene, ethylbenzene, and methyl ethyl ketone) and of water vapor on sand, clay, and limestone has been analyzed. The influence of the presence of water on the adsorption of these compounds has also been analyzed working at levels below the limit of applicability of Henry's law. The levels of relative air humidity used were 20 and 50%. The results show a big difference between the adsorption levels of the three soil minerals and a higher adsorption for polar compounds than for aliphatic and aromatic compounds. The water affects the VOC adsorption by decreasing the retention of these compounds to a greater extent for aromatic and aliphatic compounds than for the polar compound and by linearizing the isotherms. This reduction has been quantified by a simple exponential equation.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The adsorption of volatile organic compounds (VOC) onto soils plays an important role in the mobility of these kinds of contaminant through soils. It is therefore of interest to learn more about the mechanisms of interaction between VOC and soil particles. An experimental study has been carried out in order to determine the adsorption isotherms of volatile organic gases of different properties on soil minerals of different characteristics, working in a wide range of compound concentrations. The adsorption of seven organic compounds concentrations. The adsorption of seven organic compounds (n- hexane, n-heptane, n-octane, toluene, xylene, ethylbenzene, and methyl ethyl ketone) and of water vapor on sand, clay, and limestone has been analyzed. The influence of the presence of water on the adsorption of these compounds has also been analyzed working at levels below the limit of applicability of Henry’s law. The levels of relative air humidity used were 20 and 50%. The results show a big difference between the adsorption levels of the three soil minerals and a higher adsorption for polar compounds than for aliphatic and aromatic compounds. The water affects the VOC adsorption by decreasing the retention of these compounds to a greater extent for aromatic and aliphatic compounds than for the polar compound and by linearizing the isotherms. This reduction has been quantified by a simple exponential equation.
Alzueta, María U; Bilbao, Rafael; Millera, Ángela; Glarborg, Peter; Østberg, Martin; Dam-Johansen, Kim
Modeling low-temperature gas reburning. NOx reduction potential and effects of mixing Journal Article
In: Energy and Fuels, vol. 12, no. 2, pp. 329–338, 1998, ISSN: 08870624.
@article{Alzueta1998,
title = {Modeling low-temperature gas reburning. NOx reduction potential and effects of mixing},
author = {María U Alzueta and Rafael Bilbao and Ángela Millera and Peter Glarborg and Martin Østberg and Kim Dam-Johansen},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef9701293},
issn = {08870624},
year = {1998},
date = {1998-01-01},
journal = {Energy and Fuels},
volume = {12},
number = {2},
pages = {329--338},
publisher = {American Chemical Society},
abstract = {A model for simulating reburning in semi-industrial scale has been developed. It consists of a recently developed reaction mechanism for reburning with C1 and C2 hydrocarbons, in combination with ideal reactor modeling and a simplified mixing approach. The reaction mechanism as well as the mixing model has been validated separately against experimental data from laboratory and pilot scale tests. Modeling predictions have been compared with experimental data from a number of pilot scale studies of gas reburning with good results. The large differences in reburn efficiency reported in different low-temperature pilot scale experiments are reconciled in terms of the different operating conditions used. The model has been used to assess the potential of the reburn process at low temperatures, and recommendations for process optimization are provided. Results show that the low-temperature gas reburn process has a significant potential for NO reduction and that both the reburn and burnout regions are important in process optimization.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
A model for simulating reburning in semi-industrial scale has been developed. It consists of a recently developed reaction mechanism for reburning with C1 and C2 hydrocarbons, in combination with ideal reactor modeling and a simplified mixing approach. The reaction mechanism as well as the mixing model has been validated separately against experimental data from laboratory and pilot scale tests. Modeling predictions have been compared with experimental data from a number of pilot scale studies of gas reburning with good results. The large differences in reburn efficiency reported in different low-temperature pilot scale experiments are reconciled in terms of the different operating conditions used. The model has been used to assess the potential of the reburn process at low temperatures, and recommendations for process optimization are provided. Results show that the low-temperature gas reburn process has a significant potential for NO reduction and that both the reburn and burnout regions are important in process optimization.
García, Lucía; Salvador, María L; Bilbao, Rafael; Arauzo, Jesús
Influence of calcination and reduction conditions on the catalyst performance in the pyrolysis process of biomass Journal Article
In: Energy and Fuels, vol. 12, no. 1, pp. 139–143, 1998, ISSN: 08870624.
@article{Garcia1998,
title = {Influence of calcination and reduction conditions on the catalyst performance in the pyrolysis process of biomass},
author = {Lucía García and María L Salvador and Rafael Bilbao and Jesús Arauzo},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef970097j},
issn = {08870624},
year = {1998},
date = {1998-01-01},
journal = {Energy and Fuels},
volume = {12},
number = {1},
pages = {139--143},
publisher = {American Chemical Society},
abstract = {The influence of several preparation parameters on the performance of a coprecipitated nickel alumina catalyst for use in the pyrolysis of lignocellulosic residues has been studied. The variables considered were calcination temperature (750 and 850 °C), reduction time (1, 2, and 3 h), and hydrogen flow in the reduction step (1740 and 3080 cm3 (STP)/min). The catalyst performance was evaluated on a bench scale plant equipped with a continuous fluidized bed reactor using the Waterloo fast pyrolysis process (WFPP) technology. The biomass used was pine sawdust and the reaction temperature was 650 °C. The results show that when the higher calcination temperature is applied, more severe operating conditions on the reduction process must also be applied, but catalyst sintering can appear when very severe reduction conditions are used.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
The influence of several preparation parameters on the performance of a coprecipitated nickel alumina catalyst for use in the pyrolysis of lignocellulosic residues has been studied. The variables considered were calcination temperature (750 and 850 °C), reduction time (1, 2, and 3 h), and hydrogen flow in the reduction step (1740 and 3080 cm3 (STP)/min). The catalyst performance was evaluated on a bench scale plant equipped with a continuous fluidized bed reactor using the Waterloo fast pyrolysis process (WFPP) technology. The biomass used was pine sawdust and the reaction temperature was 650 °C. The results show that when the higher calcination temperature is applied, more severe operating conditions on the reduction process must also be applied, but catalyst sintering can appear when very severe reduction conditions are used.
Alzueta, María U; Bilbao, Rafael; Millera, Ángela; Oliva, Miriam; Ibañez, J C
Interactions between nitric oxide and urea under flow reactor conditions Journal Article
In: Energy and Fuels, vol. 12, no. 5, pp. 1001–1007, 1998, ISSN: 08870624.
@article{Alzueta1998a,
title = {Interactions between nitric oxide and urea under flow reactor conditions},
author = {María U Alzueta and Rafael Bilbao and Ángela Millera and Miriam Oliva and J C Ibañez},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ef980055a},
issn = {08870624},
year = {1998},
date = {1998-01-01},
journal = {Energy and Fuels},
volume = {12},
number = {5},
pages = {1001--1007},
publisher = {American Chemical Society},
abstract = {An experimental and theoretical study of the interactions between urea and NO under lean selective noncatalytic reduction conditions 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 the temperature, oxygen concentration, and urea/NO ratio on the NO reduction has been analyzed. A reaction mechanism including literature NHs, HNCO, and moist CO oxidation subsets as well as their interactions with NO and reactions describing urea thermal decomposition have been used for calculations. The results show that urea is effective in reducing NO in a given temperature window, accompanied by the formation of an appreciable amount of N2O, which reaches its maximum value for the higher NO reduction. The impact of oxygen concentration in the 1-10% range is appreciable, and lower O2 concentrations shift the reduction regime toward higher temperatures, the higher N2O formation being observed for the richer environment. Using urea, the onset of NO reduction is shifted to higher temperatures compared to the use of ammonia, even though the effective temperature window for NO reduction roughly coincides for both selective reduction agents. The efficiency of NO reduction and the NO to N2O conversion increase as the urea/NO ratio increases, even though at high temperatures the excess of urea can be oxidized to NO. Model predictions are in good agreement with the experimental results and indicate that the classical reaction pathway for urea decomposition (i.e., H2N-CO-NH2 → NH3 + HNCO) is not able alone to reproduce the experimental findings obtained in the upper temperature range. This is attributed either to uncertainties of the HNCO oxidation mechanism or to the fact that other decomposition channels are likely to be produced. Results of this work as well as other literature data suggest that the method chosen for urea injection is important with respect to the N2O emissions attained. Adding urea at least partially decomposed prior to its interaction with NO results in similar NO reduction efficiencies but in considerably lower N2O concentrations.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
An experimental and theoretical study of the interactions between urea and NO under lean selective noncatalytic reduction conditions 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 the temperature, oxygen concentration, and urea/NO ratio on the NO reduction has been analyzed. A reaction mechanism including literature NHs, HNCO, and moist CO oxidation subsets as well as their interactions with NO and reactions describing urea thermal decomposition have been used for calculations. The results show that urea is effective in reducing NO in a given temperature window, accompanied by the formation of an appreciable amount of N2O, which reaches its maximum value for the higher NO reduction. The impact of oxygen concentration in the 1-10% range is appreciable, and lower O2 concentrations shift the reduction regime toward higher temperatures, the higher N2O formation being observed for the richer environment. Using urea, the onset of NO reduction is shifted to higher temperatures compared to the use of ammonia, even though the effective temperature window for NO reduction roughly coincides for both selective reduction agents. The efficiency of NO reduction and the NO to N2O conversion increase as the urea/NO ratio increases, even though at high temperatures the excess of urea can be oxidized to NO. Model predictions are in good agreement with the experimental results and indicate that the classical reaction pathway for urea decomposition (i.e., H2N-CO-NH2 → NH3 + HNCO) is not able alone to reproduce the experimental findings obtained in the upper temperature range. This is attributed either to uncertainties of the HNCO oxidation mechanism or to the fact that other decomposition channels are likely to be produced. Results of this work as well as other literature data suggest that the method chosen for urea injection is important with respect to the N2O emissions attained. Adding urea at least partially decomposed prior to its interaction with NO results in similar NO reduction efficiencies but in considerably lower N2O concentrations.
García, Lucía; Salvador, María L; Arauzo, Jesús; Bilbao, Rafael
Influence of catalyst weight/biomass flow rate ratio on gas production in the catalytic pyrolysis of pine sawdust at low temperatures Journal Article
In: Industrial and Engineering Chemistry Research, vol. 37, no. 10, pp. 3812–3819, 1998, ISSN: 08885885.
@article{Garcia1998a,
title = {Influence of catalyst weight/biomass flow rate ratio on gas production in the catalytic pyrolysis of pine sawdust at low temperatures},
author = {Lucía García and María L Salvador and Jesús Arauzo and Rafael Bilbao},
url = {https://pubs.acs.org/sharingguidelines},
doi = {10.1021/ie9801960},
issn = {08885885},
year = {1998},
date = {1998-01-01},
journal = {Industrial and Engineering Chemistry Research},
volume = {37},
number = {10},
pages = {3812--3819},
publisher = {American Chemical Society},
abstract = {Pine sawdust catalytic pyrolysis has been studied in a fluidized bed at temperatures of 650 and 700 °C. The experimental work was carried out in a bench-scale plant based on Waterloo Fast Pyrolysis Process (WFPP) technology. The Ni-Al catalyst used was prepared by coprecipitation with a molar ratio 1:2 (Ni-Al) and calcined at 750 °C for 3 h. The catalyst was not reduced prior to the biomass reaction. The influence of the catalyst weight/biomass flow rate ratio (Wl mb) on the product distribution and on the quality of the gas product obtained was analyzed. An increase of the W/mb ratio increases the total gas yield and diminishes the liquid yield. When the W/mb ratio increases, H2 and CO yields increase while CO2, CH4, and C2 yields decrease. For W/mb ratios ≥ 0.4 h, no significant modifications are observed on the initial yields of different gases, and it is confirmed that under these conditions the initial gas composition is similar to that for thermodynamic equilibrium. For W/mb ratios < 0.4 h, a simple first-order kinetic equation has been suggested for H2 and CO formation. textcopyright 1998 American Chemical Society.},
keywords = {},
pubstate = {published},
tppubtype = {article}
}
Pine sawdust catalytic pyrolysis has been studied in a fluidized bed at temperatures of 650 and 700 °C. The experimental work was carried out in a bench-scale plant based on Waterloo Fast Pyrolysis Process (WFPP) technology. The Ni-Al catalyst used was prepared by coprecipitation with a molar ratio 1:2 (Ni-Al) and calcined at 750 °C for 3 h. The catalyst was not reduced prior to the biomass reaction. The influence of the catalyst weight/biomass flow rate ratio (Wl mb) on the product distribution and on the quality of the gas product obtained was analyzed. An increase of the W/mb ratio increases the total gas yield and diminishes the liquid yield. When the W/mb ratio increases, H2 and CO yields increase while CO2, CH4, and C2 yields decrease. For W/mb ratios ≥ 0.4 h, no significant modifications are observed on the initial yields of different gases, and it is confirmed that under these conditions the initial gas composition is similar to that for thermodynamic equilibrium. For W/mb ratios < 0.4 h, a simple first-order kinetic equation has been suggested for H2 and CO formation. textcopyright 1998 American Chemical Society.