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Enrico Biagini - One of the best experts on this subject based on the ideXlab platform.
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Development of a Variable Activation Energy Model for Biomass Devolatilization
Energy & Fuels, 2009Co-Authors: Enrico Biagini, Ludovica Guerrini, Cristiano NicolellaAbstract:A thermogravimetric balance is used in this work to characterize different classes of biomass fuels: residues (rice husks, olive cake, cacao shells), woods (poplar, beech, pellets), and grasses (mischantus). The effect of the heating rate is evaluated in the range 10-80 K/min providing significant parameters for the fingerprinting of the fuels. Kinetic parameters are obtained by applying traditional isoconversional methods. The activation energy as a function of the conversion reveals the multistep nature of the biomass Devolatilization. Although average values allow the reactivity of different fuels to be compared, a first-order reaction model can hardly predict the biomass Devolatilization in the whole range of conversions. A VEB (variable activation energy model for biomass Devolatilization) model is developed, based on the results of the kinetic analysis, maintaining a simple kinetic scheme. A good agreement is obtained for the biomass residues in all HR runs in the entire range of temperatures. The multistep mechanism can be studied without assuming any chemical components or pseudocomponents, thus limiting the number of model parameters. Similarities in the optimized VEB curves for the fuels studied in this work give useful generalization parameters for biomass Devolatilization modeling
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Development of a variable activation energy model for biomass Devolatilization
Energy and Fuels, 2009Co-Authors: Enrico Biagini, Ludovica Guerrini, Cristiano NicolellaAbstract:A thermogravimetric balance is used in this work to characterize different classes of biomass fuels: residues (rice husks, olive cake, cacao shells), woods (poplar, beech, pellets), and grasses (mischantus). The effect of the heating rate is evaluated in the range 10?80 K/min providing significant parameters for the fingerprinting of the fuels. Kinetic parameters are obtained by applying traditional isoconversional methods. The activation energy as a function of the conversion reveals the multistep nature of the biomass Devolatilization. Although average values allow the reactivity of different fuels to be compared, a first-order reaction model can hardly predict the biomass Devolatilization in the whole range of conversions. A VEB (variable activation energy model for biomass Devolatilization) model is developed, based on the results of the kinetic analysis, maintaining a simple kinetic scheme. A good agreement is obtained for the biomass residues in all HR runs in the entire range of temperatures. The multistep mechanism can be studied without assuming any chemical components or pseudocomponents, thus limiting the number of model parameters. Similarities in the optimized VEB curves for the fuels studied in this work give useful generalization parameters for biomass Devolatilization modeling.\nA thermogravimetric balance is used in this work to characterize different classes of biomass fuels: residues (rice husks, olive cake, cacao shells), woods (poplar, beech, pellets), and grasses (mischantus). The effect of the heating rate is evaluated in the range 10?80 K/min providing significant parameters for the fingerprinting of the fuels. Kinetic parameters are obtained by applying traditional isoconversional methods. The activation energy as a function of the conversion reveals the multistep nature of the biomass Devolatilization. Although average values allow the reactivity of different fuels to be compared, a first-order reaction model can hardly predict the biomass Devolatilization in the whole range of conversions. A VEB (variable activation energy model for biomass Devolatilization) model is developed, based on the results of the kinetic analysis, maintaining a simple kinetic scheme. A good agreement is obtained for the biomass residues in all HR runs in the entire range of temperatures. The multistep mechanism can be studied without assuming any chemical components or pseudocomponents, thus limiting the number of model parameters. Similarities in the optimized VEB curves for the fuels studied in this work give useful generalization parameters for biomass Devolatilization modeling.
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effect of the heating rate on the Devolatilization of biomass residues
Thermochimica Acta, 2008Co-Authors: Enrico Biagini, A Fantei, Leonardo TognottiAbstract:Abstract The Devolatilization is the basic step of thermochemical processes and requires a fundamental characterization. Three biomass residues (rice husks, olive cake, cacao shells) are studied here in a thermogravimetric (TG) balance. The effect of the heating rate (HR) is evaluated in the range 5–100 K/min providing significant parameters for the fingerprinting of the fuels. Kinetics are obtained by applying traditional isoconversional methods. The activation energy as function of the conversion reveals the multi-step nature of the biomass Devolatilization. Although average values allow the reactivity of different fuels to be compared, a first order reaction model can hardly predict the biomass Devolatilization. A VEB (Variable activation Energy model for Biomass Devolatilization) model is developed, basing on the results of the kinetic analysis. A good agreement is obtained for the biomass residues in all HR runs in the entire range of temperatures. Similarities in the optimized E VEB curves for the three fuels of this work suggest to pursue a generalization in the approach, enlarging the number and variety of fuels studied.
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Effect of the heating rate on the Devolatilization of biomass residues
Thermochimica Acta, 2008Co-Authors: Enrico Biagini, A Fantei, Leonardo TognottiAbstract:The Devolatilization is the basic step of thermochemical processes and requires a fundamental characterization. Three biomass residues (rice husks, olive cake, cacao shells) are studied here in a thermogravimetric (TG) balance. The effect of the heating rate (HR) is evaluated in the range 5-100 K/min providing significant parameters for the fingerprinting of the fuels. Kinetics are obtained by applying traditional isoconversional methods. The activation energy as function of the conversion reveals the multi-step nature of the biomass Devolatilization. Although average values allow the reactivity of different fuels to be compared, a first order reaction model can hardly predict the biomass Devolatilization. A VEB (Variable activation Energy model for Biomass Devolatilization) model is; developed, basing on the results of the kinetic analysis. A good agreement is obtained for the biomass residues in all HR runs in the entire range of temperatures. Similarities in the optimized E-VEB curves for the three fuels of this work suggest to pursue a generalization in the approach, enlarging the number and variety of fuels studied. (C) 2008 Elsevier B.V. All rights reserved
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Devolatilization of biomass fuels and biomass components studied by tg ftir technique
Industrial & Engineering Chemistry Research, 2006Co-Authors: Enrico Biagini, Federica Barontini, Leonardo TognottiAbstract:Biomass fuels represent a renewable energy source, they are CO2 neutral fuels, and their use reduces the consumption of fossil fuels and limits the emissions of SOx, NOx, and heavy metals. They are used in pyrolysis, gasification, combustion, and co-combustion. The Devolatilization is a fundamental mechanism in all these processes, especially for high volatile matter fuels. In this work, the Devolatilization of biomass fuels (of different origin, properties, and composition) and biomass components is studied coupling thermogravimetric (TG) analysis with infrared spectroscopy. The characteristic temperatures are determined for the main Devolatilization steps and compared for all fuels. A bituminous coal and a paper sludge are also studied for comparison. Light gases released (CO, CO2, H2O, CH4, CH3OH, HCOOH) are detected, whereas more complex organic (hydrocarbon and oxygenated) compounds are grouped because of the large variety of volatile species released in a narrow range of temperature. The weight loss...
Leonardo Tognotti - One of the best experts on this subject based on the ideXlab platform.
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effect of the heating rate on the Devolatilization of biomass residues
Thermochimica Acta, 2008Co-Authors: Enrico Biagini, A Fantei, Leonardo TognottiAbstract:Abstract The Devolatilization is the basic step of thermochemical processes and requires a fundamental characterization. Three biomass residues (rice husks, olive cake, cacao shells) are studied here in a thermogravimetric (TG) balance. The effect of the heating rate (HR) is evaluated in the range 5–100 K/min providing significant parameters for the fingerprinting of the fuels. Kinetics are obtained by applying traditional isoconversional methods. The activation energy as function of the conversion reveals the multi-step nature of the biomass Devolatilization. Although average values allow the reactivity of different fuels to be compared, a first order reaction model can hardly predict the biomass Devolatilization. A VEB (Variable activation Energy model for Biomass Devolatilization) model is developed, basing on the results of the kinetic analysis. A good agreement is obtained for the biomass residues in all HR runs in the entire range of temperatures. Similarities in the optimized E VEB curves for the three fuels of this work suggest to pursue a generalization in the approach, enlarging the number and variety of fuels studied.
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Effect of the heating rate on the Devolatilization of biomass residues
Thermochimica Acta, 2008Co-Authors: Enrico Biagini, A Fantei, Leonardo TognottiAbstract:The Devolatilization is the basic step of thermochemical processes and requires a fundamental characterization. Three biomass residues (rice husks, olive cake, cacao shells) are studied here in a thermogravimetric (TG) balance. The effect of the heating rate (HR) is evaluated in the range 5-100 K/min providing significant parameters for the fingerprinting of the fuels. Kinetics are obtained by applying traditional isoconversional methods. The activation energy as function of the conversion reveals the multi-step nature of the biomass Devolatilization. Although average values allow the reactivity of different fuels to be compared, a first order reaction model can hardly predict the biomass Devolatilization. A VEB (Variable activation Energy model for Biomass Devolatilization) model is; developed, basing on the results of the kinetic analysis. A good agreement is obtained for the biomass residues in all HR runs in the entire range of temperatures. Similarities in the optimized E-VEB curves for the three fuels of this work suggest to pursue a generalization in the approach, enlarging the number and variety of fuels studied. (C) 2008 Elsevier B.V. All rights reserved
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Devolatilization of biomass fuels and biomass components studied by tg ftir technique
Industrial & Engineering Chemistry Research, 2006Co-Authors: Enrico Biagini, Federica Barontini, Leonardo TognottiAbstract:Biomass fuels represent a renewable energy source, they are CO2 neutral fuels, and their use reduces the consumption of fossil fuels and limits the emissions of SOx, NOx, and heavy metals. They are used in pyrolysis, gasification, combustion, and co-combustion. The Devolatilization is a fundamental mechanism in all these processes, especially for high volatile matter fuels. In this work, the Devolatilization of biomass fuels (of different origin, properties, and composition) and biomass components is studied coupling thermogravimetric (TG) analysis with infrared spectroscopy. The characteristic temperatures are determined for the main Devolatilization steps and compared for all fuels. A bituminous coal and a paper sludge are also studied for comparison. Light gases released (CO, CO2, H2O, CH4, CH3OH, HCOOH) are detected, whereas more complex organic (hydrocarbon and oxygenated) compounds are grouped because of the large variety of volatile species released in a narrow range of temperature. The weight loss...
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characterization of Devolatilization of secondary fuels in different conditions
Combustion Science and Technology, 2004Co-Authors: Enrico Biagini, C Fantozzi, Leonardo TognottiAbstract:The applicability of secondary fuels in practical plants (combustion, pyrolysis, gasification) requires a detailed characterization, mainly in severe thermal conditions, to provide optimized parameters for design and modeling purposes. Devolatilization is the basic step in all thermal treatments of materials. An experimental procedure is developed, described, and applied to the Devolatilization of biomass (lignin-cellulosic materials), wastes (paper and sewage sludges), and low-quality coals. It consists of a preliminary characterization followed by further investigation (TG-FTIR analysis, kinetic abstraction, analysis on solid residue) to shed light on the effects of different operating conditions. The volatile matter released is found to strongly depend on the conditions used during the thermal treatment. Kinetics of Devolatilization are obtained as functions of the heating rate in a wide range of conditions using different facilities on a laboratory scale (TG balance, wire mesh reactor, electrodynamic ...
Cristiano Nicolella - One of the best experts on this subject based on the ideXlab platform.
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Development of a Variable Activation Energy Model for Biomass Devolatilization
Energy & Fuels, 2009Co-Authors: Enrico Biagini, Ludovica Guerrini, Cristiano NicolellaAbstract:A thermogravimetric balance is used in this work to characterize different classes of biomass fuels: residues (rice husks, olive cake, cacao shells), woods (poplar, beech, pellets), and grasses (mischantus). The effect of the heating rate is evaluated in the range 10-80 K/min providing significant parameters for the fingerprinting of the fuels. Kinetic parameters are obtained by applying traditional isoconversional methods. The activation energy as a function of the conversion reveals the multistep nature of the biomass Devolatilization. Although average values allow the reactivity of different fuels to be compared, a first-order reaction model can hardly predict the biomass Devolatilization in the whole range of conversions. A VEB (variable activation energy model for biomass Devolatilization) model is developed, based on the results of the kinetic analysis, maintaining a simple kinetic scheme. A good agreement is obtained for the biomass residues in all HR runs in the entire range of temperatures. The multistep mechanism can be studied without assuming any chemical components or pseudocomponents, thus limiting the number of model parameters. Similarities in the optimized VEB curves for the fuels studied in this work give useful generalization parameters for biomass Devolatilization modeling
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Development of a variable activation energy model for biomass Devolatilization
Energy and Fuels, 2009Co-Authors: Enrico Biagini, Ludovica Guerrini, Cristiano NicolellaAbstract:A thermogravimetric balance is used in this work to characterize different classes of biomass fuels: residues (rice husks, olive cake, cacao shells), woods (poplar, beech, pellets), and grasses (mischantus). The effect of the heating rate is evaluated in the range 10?80 K/min providing significant parameters for the fingerprinting of the fuels. Kinetic parameters are obtained by applying traditional isoconversional methods. The activation energy as a function of the conversion reveals the multistep nature of the biomass Devolatilization. Although average values allow the reactivity of different fuels to be compared, a first-order reaction model can hardly predict the biomass Devolatilization in the whole range of conversions. A VEB (variable activation energy model for biomass Devolatilization) model is developed, based on the results of the kinetic analysis, maintaining a simple kinetic scheme. A good agreement is obtained for the biomass residues in all HR runs in the entire range of temperatures. The multistep mechanism can be studied without assuming any chemical components or pseudocomponents, thus limiting the number of model parameters. Similarities in the optimized VEB curves for the fuels studied in this work give useful generalization parameters for biomass Devolatilization modeling.\nA thermogravimetric balance is used in this work to characterize different classes of biomass fuels: residues (rice husks, olive cake, cacao shells), woods (poplar, beech, pellets), and grasses (mischantus). The effect of the heating rate is evaluated in the range 10?80 K/min providing significant parameters for the fingerprinting of the fuels. Kinetic parameters are obtained by applying traditional isoconversional methods. The activation energy as a function of the conversion reveals the multistep nature of the biomass Devolatilization. Although average values allow the reactivity of different fuels to be compared, a first-order reaction model can hardly predict the biomass Devolatilization in the whole range of conversions. A VEB (variable activation energy model for biomass Devolatilization) model is developed, based on the results of the kinetic analysis, maintaining a simple kinetic scheme. A good agreement is obtained for the biomass residues in all HR runs in the entire range of temperatures. The multistep mechanism can be studied without assuming any chemical components or pseudocomponents, thus limiting the number of model parameters. Similarities in the optimized VEB curves for the fuels studied in this work give useful generalization parameters for biomass Devolatilization modeling.
Reginald E. Mitchell - One of the best experts on this subject based on the ideXlab platform.
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high heating rate Devolatilization kinetics of pulverized biomass fuels
Energy & Fuels, 2018Co-Authors: Joakim Myung Johansen, Peter Arendt Jensen, Peter Glarborg, Nikolai De Martini, Paul Ek, Reginald E. MitchellAbstract:Devolatilization kinetics for the biomass fuels miscanthus, leached miscanthus, and KCl-doped pinewood were determined at high heating rates (∼105 K s–1), high peak temperatures (1405–1667 K), and short residence times (<70 ms). The particle temperature and residence time distribution were obtained from computational fluid dynamic simulations. The measured Devolatilization rates, formulated in terms of single first-order reactions, were significantly faster than data reported in the literature. This difference was attributed partly to the fast heating rate/high-temperature conditions of the present study and partly to a more accurate estimate of the particle temperature. The current results indicate that neither the biomass type nor the alkali content of the biomass has a significant impact on the Devolatilization rate under the investigated conditions. The development in the particle morphology was studied by electron microscopy as each fuel underwent partial to full conversion. The char yields ranged fr...
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extension of apparent Devolatilization kinetics from thermally thin to thermally thick particles in zero dimensions for woody biomass
Energy, 2016Co-Authors: Joakim Myung Johansen, Peter Arendt Jensen, Peter Glarborg, Marco Mancini, Roman Weber, Reginald E. MitchellAbstract:This work aims to provide an accurate and simple model, predicting the time dependent Devolatilization of woody biomass at conditions (Tgas < 2000 K) and particle sizes (<2 mm) relevant to suspension fired boilers. The zero dimensional model is developed from reference calculations with a one-dimensional heat transport model coupled with a drying and a Devolatilization model. The model output has been used to generate pyrolysis kinetics corrected for non-isothermal effects, i.e. intraparticle heat transport limitations. Analysis of the modeling results indicate that heat transport corrections of even small particles are necessary. The current work divides a given particle size distribution into suitable size categories based on their internal heat transport properties. The Devolatilization is described by size category specific rate constants based on a single first order reaction mechanism. This approach allows for significantly more accurate Devolatilization predictions of any particle size distribution to be described by simple kinetic mechanisms and isothermal particle heat balances. Such an approach is easily implemented into most commercial CFD (computational fluid dynamics) codes without adding any additional strain to the computational requirements.
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Release of inorganic material during coal Devolatilization
Combustion and Flame, 1997Co-Authors: L.l. Baxter, Reginald E. Mitchell, Thomas H. FletcherAbstract:Experimental results presented in this paper indicate that coal Devolatilization products convectively remove a fraction of the nonvolatile components of inorganic material atomically dispersed in the coal matrix. Results from three facilities burning six different coals illustrate this mechanism of ash transformation and release from coal particles. Titanium is chosen to illustrate this type of mass release from coal particles on the basis of its low volatility and mode of occurrence in the coal. During moderate rates of Devolatilization (lo4 K/s heating rate), no significant loss of titanium is noted. At more rapid rates of heating/Devolatilization (10’ K/s) a consistent but minor (3%-4%) loss of titanium is noted. During rapid Devolatilization (5 X lo5 K/s and higher), significant (lo%-20%) amounts of titanium leave the coal. The loss of titanium monitored in coals ranging in rank from subbituminous to high-volatile bituminous coals and under conditions typical of pulverized-coal combustion. The amount of titanium lost during Devolatilization exhibits a complex rank dependence. These results imply that other atomically dispersed material (alkali and alkaline earth elements) may undergo similar mechanisms of transformation and release. Copyright 0 1997 by The
Yi Cheng - One of the best experts on this subject based on the ideXlab platform.
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Modeling pyrolysis of asphalt using Chemical Percolation Devolatilization theory
Fuel, 2017Co-Authors: Yan Cheng, Tianyang Li, Hang An, Yue Li, Yi ChengAbstract:Abstract Chemical Percolation Devolatilization (CPD) theory was applied to investigate the Devolatilization performance of asphalt. On the basis of the original CPD model, algebraic approaches for two chemical structure parameters (i.e., initial intact bridge and char bridge fractions) were modified with the consideration of the structure features of asphalt sample. The 13C NMR analysis data of the sample were adopted to determine the modified chemical structure parameters, while kinetic parameters were fitted based on the data of thermogravimetric analysis. Two sub-models, i.e., the distillation model and the cross-linking model, were found to be indispensable for describing asphalt Devolatilization. As a result, the model predictions revealed the evolution of bridge variables during Devolatilization, which helped to interpret the reaction procedures in detail. Further discussion was made to theoretically predict the yields of products at different heating rates, and the results indicated that an increasing heating rate did benefit the yield of the total volatiles from the asphalt sample.
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Generalized model of heat transfer and volatiles evolution inside particles for coal Devolatilization
Aiche Journal, 2014Co-Authors: Yan Cheng, Pengcheng Xu, Yi ChengAbstract:Devolatilization is acknowledged as the first important step in coal conversion techniques. A comprehensive heat transfer and Devolatilization model was established, with special consideration of the particle-scale physics and chemistry, to predict the internal heat transport and pyrolysis behavior of particles. The chemical percolation Devolatilization model with corrected kinetic parameters and structure parameters was validated with a lot of experimental data and then adopted to describe the Devolatilization behaviors under a broader range of temperatures, heating rates, and coal types. The newly achieved understanding of the integrated effect of heating rate and coal type on coal Devolatilization could help to provide a preliminary coal rank selection method for industrial processes. In particular, in-depth discussion of the influences of heat conduction, volatiles diffusion, and endothermic heat of Devolatilization inside particle indicated the dominant roles of these factors when the intensity of heat transfer was strong or the release of volatiles was rapid. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2893–2906, 2014
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analysis of particle heating and Devolatilization during rapid coal pyrolysis in a thermal plasma reactor
Fuel Processing Technology, 2012Co-Authors: Yi ChengAbstract:Abstract Using thermal plasma for coal pyrolysis to acetylene provides a direct route to make chemicals from coal resources, where the temperature field in the reactor plays a dominant role in the performance of coal Devolatilization. A comprehensive computational fluid dynamics with discrete phase model (CFD-DPM) has been established to describe the rapid coal pyrolysis process in a reactor under ultra-high temperatures. The simulations based on this model helped to understand the complex gas–particle reaction behavior in the millisecond process of coal pyrolysis. The particle-scale physics such as the heat conduction inside solid materials, diffusion of released volatile gases, coal Devolatilization, and tar cracking reactions were incorporated. The improved chemical percolation Devolatilization (CPD) model was applied to describe the Devolatilization behavior of rapidly heated coal based on the physical and chemical transformations of the coal structure. This model was proved to be qualified for describing the complex gas–particle reaction behavior with milliseconds residence time by the operation experience of a 5-MW plasma reactor. Then the simulations revealed the fact that the particle heating and Devolatilization are strongly affected by the grade of the temperature and the residence time of coal particles in the high temperature zone(s). Highly concentrated energy input in the reactor may not intensify the reactor performance. As a potential solution, multi-stage heating design would provide more flexibilities to effectively adjust the Devolatilization performances under the same energy input.