Tesi sul tema "Pyrolyse du bois"
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Grioui, Najla. "Etude thermocinétique de la pyrolyse du bois : application à la pyrolyse du bois d'olivier". Nancy 1, 2006. http://www.theses.fr/2006NAN10111.
A theoretical and experimental study of thermo-kinetic of this wood particles pyrolysis has been developed. The thermophysical properties of the olive wood such as apparent density, porosity, permeability and thermal conductivity have been determined experimentally by different measurement methods. A kinetic measurements are carried out by thermogravimetric analysis in isothermal mode in the temperature range between 498 K and 648 K. The experimental curves obtained are interpreted by a kinetic model based on several decomposition stages. The kinetic model coupled with energy conservation equation leads to a non linear equations system which has been solved iteratively by using an implicit finite differences method. The obtained results are in good agreement with the available experimental data. The developed model is then applied to the pyrolysis of a cylindrical olive wood particle in different operating condition to simulate the effect of the reactor temperature and the particle size on the evolution of the temperature profile as well as the residual mass inside the thick particle
Donnot, André. "Craquage catalytique de goudron de pyrolyse du bois". Nancy 1, 1989. http://docnum.univ-lorraine.fr/public/SCD_T_1989_0298_DONNOT.pdf.
Quirino, Waldir Ferreira. "Valorisation énergétique de déchets de bois par pyrolyse étagée". Nancy 1, 2000. http://www.theses.fr/2000NAN10220.
Ratte, Julien. "Modélisation d'un réacteur de pyrolyse lente de bois pollué". Pau, 2009. http://www.theses.fr/2009PAUU3019.
The slow pyrolysis is a solution of elimination and valuation of waste waste, that they are treated or not. It is an environment-friendly solution of treatment based on the thermal degradation of the organic matter. A mathematical model including the transfers of heat and mass and the chemical reactions of thermal degradation of a wooden particle was built. A spherical particle is warmed by a convective stream of nitrogen. The overall process is characterized by three big stages: 1) Drying of the sample; 2) Heating of the sample until the reactions of pyrolysis start; 3) Pyrolysis and production of char and volatile matters. The mathematical model is based on the concept of the method of volume averaging and allows to describe the internal profiles of several variables (temperature, moisture, wood concentration). This last one is then injected in a global model of industrial reactor. The final purpose is to build a tool to assist in designing and optimizing of industrial unit of wood waste
Senga, kiesse Silao Esperance. "Valorisation énergétique des déchets de bois traités par voies thermochimiques (pyrolyse et hydroliquéfaction) : Application aux bois traités aux sels de CCB (cuivre-chrome-bore)". Phd thesis, Ecole des Mines de Nantes, 2013. http://tel.archives-ouvertes.fr/tel-00813887.
Permadi, Pipin. "Optimisation du traitement thermique appliqué au bois d'oeuvre pour l'amélioration des propriétés des espèces non durables". Compiègne, 2000. http://www.theses.fr/2000COMP1270.
Placet, Vincent Perré Patrick. "Conception et exploitation d'un dispositif expérimental innovant pour la caractérisation du comportement viscoélastique et de la dégradation thermique du bois dans des conditions sévères". [S.l.] : [s.n.], 2006. http://www.scd.uhp-nancy.fr/docnum/SCD_T_2006_0102_PLACET.pdf.
Rousset, Patrick. "Choix et validation expérimentale d'un modèle de pyrolyse pour le bois traité par haute température : de la micro-particule au bois massif". Paris, ENGREF, 2004. http://www.theses.fr/2004ENGR0018.
The thermal treatment of wood is a well known process that has been studied for many years. In spite of the large amount of research work injected into this topic, it is still a difficult task to identify the precise loss of product quality that has been incurred as a result of this process. This fact provides the motivation for a fundamental study that explains the mechanisms of thermal treatment. The first objective of this study is to adapt an existing computational model for simulating coupled heat and mass transfer in a porous medium to include the chemical reactions that arise during pyrolysis. Paralleling this work, near infrared spectrometry (NIRS) has been used to characterize large wood samples submitted to different thermal treatments. The results show that the pyrolysis model, when coupled to the comprehensive heat and mass transfer model, is able to account the effect of exothermic reactions on the internal overpressure within the board. NIRS seems to be a promising technique that we believe permits the profiles of degradation to be used to validate the computational model
Ouartassi, Bajil Zoulalian André. "Etude numérique de la dynamique des transferts couplés au sein d'un milieu poreux". S. l. : Nancy 1, 2009. http://www.scd.uhp-nancy.fr/docnum/SCD_T_2009_0039_OUARTASSI.pdf.
Bennini, Souad. "Mise au point d'une méthode d'analyse des mécanismes de pyrolyse du bois à haute température à l'aide de matériaux marqués". Toulouse 3, 1989. http://www.theses.fr/1989TOU30147.
Vîjeu, Rãzvan Andrei. "Étude de la gazéification des déchets de bois : modélisation thermochimique pour la production des combustibles gazeux propres". Nantes, 2009. http://www.theses.fr/2009NANT2017.
In the actual economical and environmental context, favorable to the development of renewable energies, gasification proves to be a viable technology for the energetic valorization of biomass waste, and in particular of wood waste. The work presented in this report is part of a wider research oriented on staged gasification, in which the three main phases (drying/pyrolysis, partial combustion and reduction) have their own separate reactors. The theoretical study concentrates on the phases of drying/pyrolysis and reduction. The 2D model developed for the first phase is based on a nodal heat transfer method and uses simple mechanisms for thermal decomposition of wood and for mass transfer within the reactor. A similar model is also developed for reduction but in 1D configuration. It takes into account the reduction reactions with water, carbon dioxide, oxygen and hydrogen and also the water-gas shift reaction for the gas phase equilibrium. The two models are validated using experimental laboratory data or literature data. In a purely exploratory approach, the knowledge acquired during the theoretical study allowed the design and construction of a pilot gasifier, containing three reactors especially developed for the three phases. The experimental data obtained aids the process optimization and highlights the steps to be taken towards an eventual pre-commercial state
Gauthier, Guillaume. "Synthèse de biocarburants de deuxième génération : étude de la pyrolyse à haute température de particules de bois centimétriques". Phd thesis, Ecole des Mines d'Albi-Carmaux, 2013. http://tel.archives-ouvertes.fr/tel-00995288.
Tran, Trong Tuan. "Comportement au feu des structures bois assemblées par des tourillons en bois densifié". Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0298.
As part of a European project, a new assembly using densified dowels to hold wooden slats is currently being validated at the structural level. This type of assembly has the advantage of not using glues and of making it possible to manufacture large-sized structures consisting only of wood. The principle consists of positioning the wooden planks as desired, then drilling and inserting densified dowels: under the effect of moisture absorption, the densified dowels swell and block the assembly, making the structure rigid.The use of this type of assembly requires a multitude of sizing and behavior checks under various stresses, including thermomechanical variations. Thus, within the framework of this thesis work, the objective will be to characterize the behavior of wood lamellar assemblies by densified dowels subjected to significant thermo-hydric stresses, in particular during the fire. To do this, we propose an approach coupled with experiments and numerical modeling. The experiments will first allow the acquisition of the basic data to develop the model. Numerical modeling will then make it possible to better understand the mechanisms involved in the fire of these types of structures in order to improve their performance. This will also reduce the number of expensive trials. The model will be validated by temperature measurements at different depths in the section of the lamellae, but also within the densified dowels. These results will then be compared to experimental tests for validation on a few fire tests under mechanical stress.This model can then be used to estimate the behavior of more complex structures subjected to fire and to provide basic data for the sizing of complete buildings. The results can also serve as a basis for amending regulatory texts such as Eurocode 5
Le, Brech Yann. "Analyse des mécanismes primaires de pyrolyse de la biomasse". Thesis, Université de Lorraine, 2015. http://www.theses.fr/2015LORR0106/document.
Current research studies focus on biomass thermochemical conversion to produce other energetic vectors more appropriate to be conveyed, such as electricity, gas or liquid products. Pyrolysis is the first mechanism occurring in all thermochemical processes for solid fuels conversion (combustion, gasification, pyrolysis). It controls in a large extent products (gas, condensables and char) distribution and composition. The prediction of pyrolysis products and the understanding of the chemical mechanisms are thus pivotal for developing thermochemical reactors. Extensive work has been conducted for more than one century but the important heterogeneity of biomasses and pyrolysis conditions make it difficult to encompass a global chemical mechanism. The aim of this study is to develop complementary analyses of pyrolysis products. Pyrolysis is conducted in a fixed bed reactor under slow pyrolysis conditions (5 K/min), for a wide range of final temperature (200°C and 500°C) and for different biomasses (miscanthus, douglas and oak). Various analytical methods have been used in order to characterise the pyrolysis products: nuclear magnetic resonance (carbon 13C and proton 1H NMR), Calorimetry, Thermogravimetry, GC/MS (Gas Chromatography and Mass spectrometry), LC/MS (Liquid Chromatography and Mass Spectrometry) and soft ionization mass spectrometry (Single Photo Ionisation SPI). Original analytical methods such as 2D NMR HETCOR 1H-13C (for the analysis of chemical moieties in char) and high temperature 1H NMR (for in-situ analysis of mobile protons) have been used. The latter allowed a novel characterization of the interaction between biomass and minerals during pyrolysis
Chhiti, Younes. "Gazéification non catalytique des huiles de pyrolyse de bois sous vapeur d'eau". Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0064/document.
Energy production from ligno-cellulosic biomass via gasification technology appears as an attractive option in the current energy context. The combination of decentralized fast pyrolysis of biomass to produce bio-oil, followed by transportation and gasification of bio-oil in bio-refinery has appeared as one of the most economically viable methods for syngas (H2+CO) production. The objective of this work is to bridge the lack of knowledge concerning the physicochemical transformation of bio-oil into syngas using non catalytic steam gasification in entrained flow reactors. This complex process involves vaporization, thermal cracking reactions with formation of gas, tars and two solid residues - char and soot - that are considered as undesirable products. This is followed by steam reforming of gas and tars, together with char and soot conversion. To better understand the process, the first step of gasification (pyrolysis) and thereafter the whole process (pyrolysis + gasification) were studied. The pyrolysis study focused on the influence of the heating rate, the final pyrolysis temperature and the ash content of bio-oil on char, tars and gas yields. At the higher heating rate char yield is smaller than 1%. In addition, ash seems to promote polymerization reactions and causes a decrease of gas yield. Concerning gasification, the effect of temperature on syngas yield and composition was studied. An increase in the reaction temperature implies higher hydrogen yield and higher solid carbon conversion. A thermodynamic equilibrium calculation showed that equilibrium was reached at 1400°C. Finally, the soot formation and oxidation mechanisms were investigated through experiments in three different atmospheres: inert (pyrolysis), rich in steam (gasification) and in the presence of oxygen (partial oxidation). A semi-empirical model was proposed and validated. It is based on detailed chemistry to describe gas phase reactions, a single reaction using C2H2 concentration to describe soot formation and one main heterogeneous reaction to describe soot oxidation
Heitz, Michèle. "Liquéfaction par fractionnement de la biomasse". Nancy 1, 1993. http://www.theses.fr/1993NAN10326.
Weiland, Jean-jacques. "Etude physico-chimique du traitement thermique du bois : Optimisation de paramètres du procédé de rétification". Grenoble INPG, 2000. http://tel.archives-ouvertes.fr/tel-00820822.
Marin, Nicolas. "Étude du comportement thermique et valorisation des déchets du bois". Metz, 2001. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2001/Marin.Nicolas.SMZ0106.pdf.
In the frame of the European program Inco-Copernicus “Bioval Network”, our study consisted in the characterization of the thermal behavior of the samples defined in the network. This was realized by thermal analysis using different experimental conditions. For the second part of this work, results of wood pyrolysis in autoclave were studied. Considering the fact that several biomass-plastic composites are actually prepared, or that waste upgrading needs treatment of biomass products and plastic materials, we also analyzed results of wood-plastic copyrolysis in autoclave. In particular, we insisted on analyzing light liquid fractions (bp < 180° C, under atmospheric pressure) of our experiments. Main results are : using two thermogravimetric configurations, obtained results are comparable so much for characteristic temperatures than for weight evolutions ; concerning kinetic parameters, obtained values are in agreement with those of the literature and the degradation of the studied polymers is independent of wood whatever its origin. This shows that during heating wood-plastic mixture, in TGA conditions, results are additive. As demonstrated in this work, the mixtures of the different types of biomass and polyolefinic polymers can be radically converted to liquid products by pyrolysis under inert atmosphere in the autoclave conditions. The origin of biomass as well as the type of polymers plays an important role on final product distribution. Obtained results demonstrate the potential of wood-plastic copyrolysis process for utilization of lignocellulosic waste in liquid production
Christodoulou, Mélina. "Pyrolyse de bois dans les conditions d'un lit fluidisé : étude expérimentale et modélisation". Thesis, Université de Lorraine, 2013. http://www.theses.fr/2013LORR0200/document.
This study contributes to the French biomass gasification project: Gaya project. It is a large R&D project financed by ADEME and coordinated by GDF SUEZ. The project GAYA will develop a demonstration platform for a new biomass gasification and methanation process. In this context, our objective is to build a biomass pyrolysis model, representative of the conditions encountered in the fluidized bed gasifier developed in this project. An experimental machine, the vertical image furnace, has been developed to reproduce the heat conditions of the fluidized bed gasifier at 850°C. This experimental model permits to collect all the pyrolysis products for a later analysis. Then, kinetics parameters are determined from both the physico-chemical process and the optimization of experimental results. The thermal cracking of condensable vapours, is studied during the first 300th milliseconds after their ejection from the biomass particle. For this purpose, cracking experiments are led on the experimental machine which combines a tubular pyrolysis reactor and a continuous self-stirred tank cracking reactor. The model developed allows us to represent the biomass pyrolysis introduced in the gasification reactor
Rousset, Patrick. "CHOIX ET VALIDATION EXPERIMENTALE D'UN MODELE DE PYROLYSE POUR LE BOIS TRAITE PAR HAUTE TEMPERATURE : DE LA MICRO-PARTICULE AU BOIS MASSIF". Phd thesis, ENGREF (AgroParisTech), 2004. http://tel.archives-ouvertes.fr/tel-00106360.
Les résultats montrent que le modèle de pyrolyse couplé au modèle de transport rend compte des différents événements caractéristiques se déroulant durant le traitement thermique, c'est-à-dire la présence de réactions exothermiques et les surpressions internes générées par les gaz produits. La méthode par analyse spectrale a révélé qu'il est possible d'une part de discriminer des échantillons de bois ayant subis différents traitements et d'autre part de retracer l'historique thermique d'une pièce de bois dans son épaisseur. La SPIR semble ainsi une technique prometteuse qui devrait permettre de valider les profils de dégradation simulés par le code de calcul. Elle devait offrir également des perspectives intéressantes en matière de contrôle qualité des bois traités à haute température pour le couplage des propriétés physiques et mécaniques du nouveau matériau à sa composition chimique.
Lin, Bo-Jhih. "Études de bois traités par pyrolyse douce dans un réacteur semi-industriel pour une production de matériaux durable : comportement thermique, changements de propriétés et modélisation cinétique". Thesis, Université de Lorraine, 2019. http://www.theses.fr/2019LORR0023/document.
Mild pyrolysis is a promising and widely applied process conducted at 200-300 °C in an inert condition to produce sustainable materials (i.e. heat treated wood) or solid fuel (i.e. torrefied wood). The aim of this study is to investigate the woods heat treated in a semi-industrial scale reactor for sustainable material production. Two different European wood species, a hardwood species (poplar, Populus nigra) and a softwood species (fir, Abies pectinata), are used to perform the experiments. The present research is divided into three parts. In the first part, the thermal behavior of wood boards is studied in a semi-industrial scale reactor. The experiments are carried out at 200-230 °C with a heating rate of 0.2 °C min-1 in a vacuum condition (200 hPa) to intensify the thermal degradation. Four different stages of thermal degradation during wood heat treatment are defined based on the intensity of differential mass loss (DML). The devolatilization characteristics of treated woods are evaluated by the devolatilization index (DI) based on the results of proximate analysis. The correlation of DI with respect to mass loss of the two wood species is strongly characterized by linear distribution, which is able to provide a simple tool to predict the mass loss of wood. In the second part of the study, a number of analyses, such as Fourier-transform infrared spectroscopy, X-ray diffraction, measurement of color change, equilibrium moisture content, and contact angle) are performed to evaluate the property changes of treated woods. The obtained results clearly demonstrate the thermal degradation through dehydration, deacetylation, depolymerization, and condensation reactions during the heat treatment. The observed phenomena of color change and hygroscopic transformation are illustrated and discussed in detail. The decarbonization, dehydrogenation, and deoxygenation of the treated woods are also evaluated. It is found that the three indexes can be well correlated to the total color difference and hygroscopicity reduction extent (HRE). In the last part of the study, the kinetic modeling of wood heat treatment is developed based on a two-step kinetic scheme. The obtained kinetics successfully predict dynamic solid yield of wood boards during the treatment in the semi-industrial reactor. Meanwhile, the prediction of elemental composition is also performed by a direct method based on the elemental analyses of untreated and treated woods at the end of the treatment, as well as the instantaneous solid yield. The results point out that the prediction of C, H, and O profiles are in good agreement with expected composition changes in the wood materials during treatment. In summary, the obtained results and established kinetics are conducive to recognizing the mechanisms of wood thermal degradation and can be used for heat treatment process and reactor design in industry to produce wood materials for various applications
Lin, Bo-Jhih. "Études de bois traités par pyrolyse douce dans un réacteur semi-industriel pour une production de matériaux durable : comportement thermique, changements de propriétés et modélisation cinétique". Electronic Thesis or Diss., Université de Lorraine, 2019. http://www.theses.fr/2019LORR0023.
Mild pyrolysis is a promising and widely applied process conducted at 200-300 °C in an inert condition to produce sustainable materials (i.e. heat treated wood) or solid fuel (i.e. torrefied wood). The aim of this study is to investigate the woods heat treated in a semi-industrial scale reactor for sustainable material production. Two different European wood species, a hardwood species (poplar, Populus nigra) and a softwood species (fir, Abies pectinata), are used to perform the experiments. The present research is divided into three parts. In the first part, the thermal behavior of wood boards is studied in a semi-industrial scale reactor. The experiments are carried out at 200-230 °C with a heating rate of 0.2 °C min-1 in a vacuum condition (200 hPa) to intensify the thermal degradation. Four different stages of thermal degradation during wood heat treatment are defined based on the intensity of differential mass loss (DML). The devolatilization characteristics of treated woods are evaluated by the devolatilization index (DI) based on the results of proximate analysis. The correlation of DI with respect to mass loss of the two wood species is strongly characterized by linear distribution, which is able to provide a simple tool to predict the mass loss of wood. In the second part of the study, a number of analyses, such as Fourier-transform infrared spectroscopy, X-ray diffraction, measurement of color change, equilibrium moisture content, and contact angle) are performed to evaluate the property changes of treated woods. The obtained results clearly demonstrate the thermal degradation through dehydration, deacetylation, depolymerization, and condensation reactions during the heat treatment. The observed phenomena of color change and hygroscopic transformation are illustrated and discussed in detail. The decarbonization, dehydrogenation, and deoxygenation of the treated woods are also evaluated. It is found that the three indexes can be well correlated to the total color difference and hygroscopicity reduction extent (HRE). In the last part of the study, the kinetic modeling of wood heat treatment is developed based on a two-step kinetic scheme. The obtained kinetics successfully predict dynamic solid yield of wood boards during the treatment in the semi-industrial reactor. Meanwhile, the prediction of elemental composition is also performed by a direct method based on the elemental analyses of untreated and treated woods at the end of the treatment, as well as the instantaneous solid yield. The results point out that the prediction of C, H, and O profiles are in good agreement with expected composition changes in the wood materials during treatment. In summary, the obtained results and established kinetics are conducive to recognizing the mechanisms of wood thermal degradation and can be used for heat treatment process and reactor design in industry to produce wood materials for various applications
Girods, Pierre. "Procédé multi-étagé de valorisation de déchets bois type panneaux de particules". Thesis, Nancy 1, 2008. http://www.theses.fr/2008NAN10026/document.
Within the environmental contexts of power generation and waste disposal, the present works deals with the validation and the optimisation of a multistage thermo chemical process of particleboard waste conversion (enhancement). These wastes are mostly associated with urea formaldehyde and melamine formaldehyde resins which contain a huge amount of nitrogen. Nitrogen causes the production of pollutants such as ammonia, isocyanic acid, cyanhydric acid and NOx… during classical thermo chemical process (combustion, pyrolysis and gasification). The process studied aims in a first time to remove nitrogen species from waste to produce a combustible solid and in a second time to convert this residual solid in a combustible gas. The first step consists in a low temperature pyrolysis (250°C to 400°C) during 3 to 15 minutes and assumes to eliminate 70 % of the initial nitrogen content for all studied conditions. The pyrolysis and/or the pyrolysis / gasification under water of the residue are then studied between 800°C and 1000°C. The higher temperature of reaction (1000°C) improves the production of gases and the energy efficiency of this second step and allow the production of hydrogen and carbon monoxide rich gases. The pyrolysis / gasification under water allows a total conversion of the solid which optimises the energy efficiency of the process. However, the pyrolysis under nitrogen produces a lower amount of gases but helps to catch a part of the nitrogen in the residual char. The char then produced is converted through an activation step, in an active char containing nitrogen functionalities with high adsorption capacities, especially for the trapping of phenol or other aromatic compounds in liquid phase. This multistage is thus a interesting way to enhance low cost raw matter like particleboard waste
Elamin, Abdelrahman. "Liquéfaction du bois en deux étapes : solvolyse et hydrotraitement". Compiègne, 1992. http://www.theses.fr/1992COMPD485.
The objectives of this work is to define a liquefaction process to produce oil from wood rich in hydrocarbons compounds so as to be usable as an alternative fuel. The investigated process consist of two steps : solvolysis and upgrading. In presence of solvents that derived from lignin or from holocellulose, the experimental results show that it is possible to dissolve completely wood powder under relatively mild reaction conditions. Among the tested solvents, the mixture of phenol/ tetralin gives a complete conversion of wood with abetter regeneration of the initial solvents used and more than 50% of the oxygen content of the wood has been removed during the solvolysis. The yield of the solvolysis oil is 70 % wt. Of the initial dry wood. The upgrading step is mainly to remove the residual oxygen of the solvolysis oil in order to increase its heating value and to lower its viscosity. In presence of tetralin as hydrogen donner solvent, at 350°C and initial hydrogen pressure of 9 MPa. Within the tested catalysts the sulfied nickel molybdeum is the more efficient hence in presence of this catalyst under the above mentioned reaction condition, the refined oil yield is around 55% and its oxygen content is less than 2%. The heating value of the refined oil is 43 MJ/kg which can be classified as that of the petroleum’s product. This study allowed determining the optimal reaction condition of the solvolysis step, as well as that of the upgrading step for producing a refined oil usable as hydrocarbon fuel from wood. The refined oil can be used effectively for dissolving wood in the solvolysis step which justify that a continuous liquefaction process able to generate its own solvent can be realised
Bohnke, Isabelle. "Étude expérimentale et théorique des traitements thermiques du bois. Caractérisation physico-mécanique des bois traités". Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 1993. http://tel.archives-ouvertes.fr/tel-00844044.
Ouarzki, Imane. "Production de bio-huile par pyrolyse de bois : application à la pré-séparation de la bio-huile". Thesis, Compiègne, 2015. http://www.theses.fr/2015COMP2194.
This research study is concerned in the production of bio-oils from the pyrolysis of beech and pines wood representing the hard and soft wood, respectively. In order to resolve the problems related to the separation of high added value molecules from the bio-oil, a study was held out on the feasibility of the pre-separation of the chemical components of bio-oil using of a staged pyrolysis temperature in a fixed bed reactor in order to target selective thermal decomposition of macro-components of biomass (hemicellulose, cellulose and lignin). The identification of macro-component couples - marker of decomposition is made from the balance macro-component in the residual solid and identification by GC / MS of the chemical components contained in the produced bio-oil. The results of this part have shown the possibility of the pre-separation of furans and phenolic derivatives, despite of the gain in selectivity at the expense of overall yield of bio-oil. The second part of this work (concerns with the study of the production of bio-oil in fast pyrolysis conditions in a gas / solid reactor. To establish a relationship between the operating conditions and chemical composition of pyrolysis bio-oil, a tool for meaningfull comparison of experiments was developed. Experiments have shown that the yield and composition of pyrolysis oil depends mainly on the composition of wood, the heating rate and the effective residence time of the wood particles into the reactor
Numazawa, Sueo. "Contribution à l'étude de la pyrolyse lente sous pression du bois. Détermination des paramètres optima du procédé et caractéristiques des produits obtenus". Compiègne, 2000. http://www.theses.fr/2000COMP1286.
Biotteau, Emilie. "Caractérisation d'un milieu poreux réactif soumis à de forts flux de chaleur : application au bois Redwood". Poitiers, 2004. http://www.theses.fr/2004POIT2327.
The major purpose of this study is a better understanding of mechanisms involved in thermal degradation of porous medium (wood for instance). Numerical and experimental investigations have been carried out. A non linear coupled differential set of equations had to be solved to describe heat and mass transfer, pyrolysis reaction and the induced solid matrix transformation. Inclusion of anisotropy has been performed using 2D-simulation. Two experimental set up have been used to investigate pyrolysis under inert and ambient atmosphere. The reactive zone has been found to be very thin compared to slab length and to propagate into the sample as time proceeds. A pyrolysis front velocity has been defined experimentally and numerically. A detailed analysis of heat and mass transfer in the sample provided an improved understanding of the front propagation mechanism. Heat conduction has been found to play a major role in the heat balance whereas chemical reactions contribution has been shown to be negligible. Under oxidative atmosphere, smoldering combustion occurs at the irradiated surface and has been shown to supply three times more heat than incident heat flux so that pyrolysis starts at lower incident heat fluxes. Inclusion of structure anisotropy leads to a paradox: pyrolysis front propagates more rapidly across than along the fibres (although heat conductivity is lower across than along fibres)
Fateh, Talal. "Etude expérimentale et numérique de la cinétique de décomposition thermique de contreplaqués en bois". Phd thesis, Chasseneuil-du-Poitou, Ecole nationale supérieure de mécanique et d'aérotechnique, 2011. http://tel.archives-ouvertes.fr/tel-00667332.
Capart, Richard. "La gazéification du bois : étude expérimentale et théorique de la pyrolyse du bois brut et des réactions d'oxydation du charbon de bois avec le dioxyde de carbone et la vapeur d'eau". Compiègne, 1991. http://www.theses.fr/1991COMPDE91.
Boer, Febrina. "Valorization of sugarcane bagasse via slow pyrolysis and its by-product for the protection of wood". Electronic Thesis or Diss., Paris, AgroParisTech, 2021. http://www.theses.fr/2021AGPT0008.
Biomass residue—such as sugarcane bagasse—has great potential in providing renewable energy sources. However, its natural properties such as low density, low calorific value, and biodegradation susceptibility can limit its utilization. To improve its energy efficiency, slow pyrolysis—the process of thermal decomposition in an oxygen-deficient environment—can be applied by transforming the biomass into carbon-rich char. In a typical slow pyrolysis scenario, biomass is slowly heated to produce mainly char, where the organic vapors are often considered secondary products. However, there is an interest to recover this by-product by condensing the organic vapor generated during pyrolysis for various purposes. Moreover, this product has a long history due to its benefits as a bio-pesticide used by traditional farmers, notably in Asian countries. In this study, bagasse was slow-pyrolyzed to co-produce char and pyrolysis liquid using a laboratory fixed bed reactor. Different parameters were tested, such as temperatures (400 °C and 500 °C), heating rate (1 °C/min and 10 °C/min), and holding time (30 min and 60 min). This study aims to evaluate the valorization potential of bagasse with the purpose of energy densification (conversion of biomass into char) and valorizing the utilization of its by-product (pyrolysis liquid) for wood protection.Results showed that the yield of char decrease with the increase of pyrolysis temperature but results in the favorable calorific value improvement; while at the same time generating a high mass of liquid yield. The optimum pyrolysis condition to co-produce char and pyrolysis liquid was at 500 °C temperature and 10 °C/min of heating rate, yielding 28.97% char and 55.46% liquid. The principal compounds of pyrolysis liquid were water, acetic acid, glycolaldehyde, 1-hydroxy-2-propanone, methanol, formic acid, levoglucosan, furfural, followed by some phenol compounds and guaiacol derivatives. Pyrolysis liquid also exhibits anti-fungal and anti-termite activity at relatively low concentrations in the Petri-dishes bioassays. When treated to beech and pine wood, pyrolysis liquid indicates good protection towards termites (Reticulitermes flavipes) and Basidiomycete fungi (Coniophora puteana and Rhodonia placenta, cubic rot and Trametes versicolor, a fibrous rot) at concentration 50% and 100%. However, it remains leachable when exposed to water or high humidity, which indicates that future studies should be conducted to find out how to decrease its leachability.Keywords: biomass, char, slow pyrolysis, sugarcane bagasse, pyrolysis liquid, wood protection
Pozzobon, Victor. "Biomass gasification under high solar heat flux". Thesis, Ecole nationale des Mines d'Albi-Carmaux, 2015. http://www.theses.fr/2015EMAC0004/document.
Concentrated solar energy is as an alternative energy source to power the thermochemical conversion of biomass into energy or materials with high added value. Production of syngas from lignocellulosic biomass is an example, as well as the production of carbonaceous residues with controlled properties. This work focuses on the study of the behaviour of a thermally thick beech wood sample under high solar heat flux (higher than 1000 kW/m²). Two approaches have been undertaken at the same time: an experimental study and the development of a numerical model. Experiments have highlighted a specific behaviour of beech wood under high solar heat flux. Indeed, a char crater, symmetrical to the incident heat flux distribution, forms in the sample. This study has also shown that biomass initial moisture content has a strong impact on its behaviour. The dry sample can achieve an energetic conversion efficiency of 90 %, capturing up to 72 % of the incident solar power in chemical form. While, high initial moisture content samples produce more hydrogen, at the price of an energetic conversion efficiency around 59 %. Furthermore, tar thermal cracking and steam reforming are enabled by the temperatures reached (higher than 1200 °C) and the presence of water. Finally, wood fiber orientation has been shown to have only a minor impact on its behaviour. At the same time, a modelling of the coupled reactions, heat and mass transfers at stake during solar gasification was undertaken. The development of this model has highlighted the necessity to implement innovative strategies to take into account radiation penetration into the medium as well as its deformation by gasification. Numerical model predictions are in good agreement with experimental observations. Based on the model predicted behaviour, further understanding of biomass behaviour under high solar heat flux was derived. In addition, sensitivity analyses revealed that Arrhenius type models are not fitted for precise intra-particular water behaviour description and that the choice of the pyrolysis scheme is key to properly model biomass behaviour under high solar heat flux
Ahmed, Hared Idriss. "Optimisation d'un procédé de pyrolyse en four tournant : application à la production de charbons actifs". Phd thesis, Toulouse, INPT, 2007. http://oatao.univ-toulouse.fr/7716/1/ahmed_hared.pdf.
Chebil, Sami. "Étude des liants bitumineux modifiés par le noir de carbone et le charbon de bois pyrolytiques, sous-produits de la décomposition thermique sous vide des pneus et du bois hors d'usage". Sherbrooke : Université de Sherbrooke, 1997.
Chen, Li. "Fast pyrolysis of millimetric wood particles between 800°C and 1000°C". Thesis, Lyon 1, 2009. http://www.theses.fr/2009LYO10258.
The present work is part of a project of the French energy research centre Commissariat à l’Energie Atomique. The goal of the project is to develop processes of production of gaseous or liquid fuel from synthesis gas obtained by gasification of lignocellulosic biomass. The objective of the present work is to study the pyrolysis behaviour of millimetric biomass particles under the operating conditions encountered in fluidized bed or entrained flow gasifiers, namely high external heat flux (105 – 106 W⋅m-2) and high temperature (> 800°C). First, pyrolysis experiments are conducted at 800 and 950°C in a lab-scale drop tube reactor on wood particles between 350 and 800 μm. The results show that under the explored conditions, the increase of the particle size only increases the time required for pyrolysis but does not affect the product distribution during pyrolysis. Since in the pyrolysis experiments, the particle residence time cannot be directly measured, PTV (Particle Tracking Velocimetry) measurements are performed at room temperature to characterize the evolution of the particle size and density along pyrolysis and to validate a drag coefficient correlation for the particle residence time calculation. The optical measurements show that at the end of pyrolysis there is a decrease of particle density of 70 – 80% and of particle size of 25 – 40%. It is also proven that the particle slip velocity cannot be neglected and that the change of these particle properties must be taken into account for the calculation of the particle slip velocity and residence time. Finally, based on these experimental results, a 1D shrinking-core model is developed that is able to predict the solid/gas/tar yields and the residence time of a single particle along pyrolysis in the drop tube reactor. It is validated on both the pyrolysis and optical experiments. The model sensitivity analysis shows that even for millimetric particles, the accurate knowledge of the heat of pyrolysis, of the wood density and of the char thermal conductivity is essential
Lorreyte, Clarisse. "Etudes numérique et expérimentale de la synthèse de biogaz : vers la transformation thermochimique solaire de copeaux de bois". Thesis, Reims, 2017. http://www.theses.fr/2017REIMS033.
Thermochemical conversion of lignocellulosic biomass belongs to attractive technologies which are viable routes to reduce reliance on fossil energy and to enhance carbon conversion efficiency. Nevertheless, classical gasification process via autothermal combustion of biomass presents severe drawbacks as bad yield and produced important pollutants. Solar concentrated energy enables high temperature reactions with reduced contaminating gas and higher yield. In this context, this thesis aims at developing experimental and numerical approaches to study detailed mechanism of pyrolysis and gasification processes of wood chips packed bed which are key step toward designing efficient solar gasifier. In a first time, inner properties of wood (initial composition and thermal decomposition) were studied via ultimate and proximate analyzes. Structural and morphological properties of wood chips were computed using image analysis. Effective mass and heat transport properties of the packed bed were assessed via direct numerical simulation combined with X-ray tomographic images. Then a laboratory scale device enabling to characterize pyrolysis and gasification kinetics and gas production was developed. The aim of this experimental work was to understand the impact of parameters such as drying and pyrolysis temperatures, and the steam flow rate during gasification. A multiphysical model of pyrolysis of wood chips packed bed was also developed. It allowed to perform detailed study of pyrolysis physics and in fine it will allow optimizing the pyrolysis/gasification process. Finally, a first design for a solar gasifier was reported and constitutes the basis of further studies
Zeng, Kuo. "Solar pyrolysis of biomass at laboratory scale". Thesis, Perpignan, 2016. http://www.theses.fr/2016PERP0008/document.
Concentrated solar energy provides heat to drive biomass pyrolysis reactions, which upgrades the feedstock energy by storing solar energy in chemical forms (bio-gas, bio-oil and bio-char). Thanks to high temperature and fast heating rate, more pyrolytic gas with high lower heating value (LHV) can be produced by direct solar pyrolysis. Experiments have highlighted the effect of solar pyrolysis parameters on products yields, composition and properties. The total gas LHV dramatically increases (5-fold) with increasing temperature (from 600°C to 1200°C) and sample heating rate (from 5°C/s to 50°C/s), which is mainly due to variations in the CO and H2 yields. The interaction between temperature and heating rate enhances at both high ranges. The maximum gas products LHV (14 589 kJ/kg of beech wood) was obtained at 2000°C and 450°C/s heating rate. The collected char and tar were analyzed and characterized, which emphasizes the temperature and heating rate effects. And the energy upgrade factor is determined as about 1.5 independent of temperature. At the same time, a 2D unsteady CFD particle model (simplified assumption using first-order Arrhenius type reactions) with heat and mass transfers was developed for solar pyrolysis. Numerical model predictions are in good agreement with experimental observations. Stoichiometric coefficients about the mass fraction of primary tar converted by the reaction to gas and secondary tar were determined at different temperatures and heating rates for the first time. The evolution of the final products and mass losses of biomass are enhanced with temperature and heating rate increase
Dufourny, Adrien. "Identification et optimisation des paramètres influant sur la qualité du charbon de bois utilisé comme agent réducteur pour la production du silicium métallurgique". Thesis, Montpellier, SupAgro, 2018. http://www.theses.fr/2018NSAM0056.
Metallurgical silicon is produced by carbothermic reduction of quartz in electric arc furnaces using carbon reducers, mostly of fossil origin. The use of charcoal is a relevant alternative to reduce the environmental impact of the metallurgical process. The coal also makes it possible to limit the presence of certain impurities in the silicon and to reduce the overall energy consumption of the process. The main obstacles to its use are its low mechanical strength as well as its cost of production which, in certain contexts, make it difficult to compete with fossil reducers. The aim of this work was to determine the interest properties of a reducing carbon, and to study the influence of the nature of the wood and the operating conditions of the pyrolysis on these properties.A fixed bed pyrolysis pilot reactor, designed specifically for this thesis, has produced charcoal in conditions similar to those encountered in industry. The coals were then characterized according to their yields and physicochemical characteristics. Characterization tests of the mechanical behavior in coal bed - resistance to compression and friability - have been developed. In addition, the CO2 reactivity of the coals was measured by means of a macro-thermogravimetric reactor. The coals were produced from two species of wood of different types, Eucalyptus globulus and Picea abies for three final pyrolysis temperatures - 500, 650 and 800 ° C - and two residence times at the final temperature - 0 and 90 min. -. The influence of the nature of the raw material was also studied through the production of charcoal with four additional species at the temperature of 700 ° C without residence time at the final pyrolysis temperature.Our results show that the nature of wood has a much greater impact on its properties as a reducing agent than the operating conditions of pyrolysis. The apparent density of wood is not a good indicator of the mechanical behavior of charcoal, as is often considered. When the final pyrolysis temperature was increased, the mechanical strength increased and the CO2 reactivity decreased. The impact of residence time at the final pyrolysis temperature on coal properties was negligible, with the exception of coal yield and CO2 reactivity, which decreased with increasing residence time. The work carried out made it possible to determine the optimal pyrolysis operating conditions as well as the most suitable gasoline for the production of a reducing charcoal for the silicon industry
Weiland, Jean-Jacques. "Etude physico-chimique du traitement thermique du bois. Optimisation de paramètres du procédé de rétification". Phd thesis, Ecole Nationale Supérieure des Mines de Saint-Etienne, 2000. http://tel.archives-ouvertes.fr/tel-00820822.
Thi, Van Diem. "Modélisation du comportement au feu des structures en bois". Thesis, Université de Lorraine, 2017. http://www.theses.fr/2017LORR0363/document.
Numerical modelling of timber structures in fire conditions requires the knowledge of the variation with temperature of the physical properties of the wood material (the thermal conductivity, the specific heat and the density) in order to take into account the thermal degradation of wood under high temperatures during the drying, pyrolysis and combustion phases, as well as the temperature profiles in the thickness of the surfaces exposed to fire. In particular, this work focusses on the thermomechanical behaviour of timber. The heat transfer analysis is described by the standard equations of heat conduction. It includes the three modes of heat transfer: conduction, radiation and convection. The structural response is modelled within the framework of thermodynamics of irreversible processes using the notion of state variables. It takes into account the coupling between the orthotropic elastic behaviour, the anisotropic plastic behaviour with isotropic nonlinear hardening, and isotropic damage. The numerical integration of the equilibrium equations is carried out with an iterative implicit scheme combining the technique of radial re- turn with the reduction of the number of equations. The thermomechanical coupling is carried out according to the approach recommended by Eurocode 5 for the fire resistance of timber structures by applying the reduction factor Kθ to the strength of a softwood. The theoretical aspects and boundary conditions associated with the thermomechanical model are also discussed. The parameters of the model are identified with experimental data obtained from actual fire tests available in the literature. Several comparative applications are carried out. The finite element model accurately reproduces the distribution of the temperature profile in the thickness of timber planks, the formation of the charred layer, and the evolution of the mechanical resistance during exposure to fire
Hentges, David Jean. "Caractérisation de la composition chimique du bois par pyrolyse flash couplée à la GC/MS : application à l'étude de la variabilité naturelle et aux modifications résultant de différents traitements". Electronic Thesis or Diss., Université de Lorraine, 2022. http://www.theses.fr/2022LORR0321.
Analytical pyrolysis is an innovative method that allows gas chromatographic analysis of complex polymers by reducing them to volatile monomers. The method requires only a few milligrams of material and is performed in a few seconds. Wood is an abundant renewable material that is used in many forms, notably in construction, in fiberboard and in the extractives it containsNumerous chemical and thermochemical modification techniques are used to improve the properties of wood, including acetylation, furfurylation and heat treatment. Pyrolysis is a new technique to characterize treated wood to understand the chemical modifications that have been generated. The classical methods used such as NMR, FTIR do not allow for a complete picture of the wood, more specifically on elements such as the regioselectivity of the modifications. The aim of our work is to answer fundamental questions about the natural variability of wood as well as the chemical modifications generated by different methods. The polymerization of furfuryl alcohol in wood could be demonstrated as well as the formation of a covalent bond with lignin. The wood acylated with different linear anhydrides revealed new structures that allow to identify the reaction sites and to estimate the reactivity of macromolecules. The method is capable of quantifying the extent of modification of the different biopolymers that constitute the wood. Using principal component analyses (PCA), the natural variations of wood as a function of height, tissue and between different specimens of the same species could be characterized. Py-GC/MS was also used to show structural differences after heat and fungal treatment to reveal how these degradations affect the wood
Margarido, Marta. "Etude sur la modélisation mathématique de la cuisson Kraft des espèces pures et mélanges de bois pour la production de pâte à papier". Grenoble INPG, 2009. http://www.theses.fr/2009INPG0138.
The behaviour during Kraft cooking of a vast series of wood species, including hardwoods and softwoods, have neen studied in a purpose of species comparison and kinetic modelling. The different species were cooked as pure species or mixtures. They were characterized in terms of chemical characteristics (lignin, polysaccharides, hexenuronic acids, pulp yield, molecular composition analysed by Py-GC-MS), and in terms of alkali diffusion properties and morphological evolution during cooking. Macroscopic measurements were completed by microtomographic images on wood chips by X-ray analysis. The results obtained contribute to a general knowledge of Kraft cooking, and also to the development of a mathematical simulator for Kraft cooking modelling
Auber, Maud. "Effet catalytique de certains inorganiques sur la sélectivité des réactions de pyrolyse rapide de biomasses et de leurs constituants". Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL041N/document.
The fast primary pyrolysis of cellulose, lignin, xylan and birch wood (natural, reconstituted, washed or not) impregnated by different types of catalysts (KCl, MgCl2, NiCl2 and ZnCl2) is experimentally studied in an image furnace. The effect of a catalyst addition differs according to the type of biopolymer. However, the decrease of the liquids and the increase of the char production rates are always observed (the effects are more or less stressed according to the nature of the catalyst). The composition of the gaseous phase is also modified with an increase of the H2 volume fraction. The nature and morphology of chars depend on the type of catalyst. The quantity and composition of the intermediate liquid compound formed during the pyrolysis of cellulose are also modified. It’s difficult to establish linear laws describing the pyrolytic behavior of biomasses from the simple overlapping of the observations made with basic biopolymers, implying the need of a modelling study. The model is based on mass and energy balances written at the level of biomasses pellets subjected to a given heat flux density. The agreement with the experimental results is quite good but suffers from a bad knowledge of the physicochemical properties of the biomasses. It is anticipated that the model could give better results if the influence of the interactions between basic biopolymers within the natural biomasses could be estimated and taken into account. Some researches in these domains could be recommended
Shah, Narendra. "Carbonisation discontinue du bois en four à combustion partielle : contribution à la connaissance des phénomènes et recherche d'une méthode de gestion". Compiègne, 1990. http://www.theses.fr/1990COMPD289.
Flity, Hassan. "Modélisation de la dégradation et combustion du bois de construction". Electronic Thesis or Diss., Université de Lorraine, 2023. http://www.theses.fr/2023LORR0250.
The use of wood in construction offers numerous advantages, but also poses fire safety risks. Several studies available in the literature, whether experimental or numerical, have investigated the fire behavior of wood. However, the diverse and varied results do not allow the identification of the intrinsic behavior of wood, and regulatory frameworks have to rely on numerous simplifying assumptions. The objective of this thesis is to study the thermal degradation of wood at the cone calorimeter scale. The uniqueness of the study lies in the adoption of an increasingly complex approach, the use of meticulous metrology, and the most comprehensive characterization of the properties of the wood samples under investigation. Degradation involves numerous interacting processes such as drying, pyrolysis, and combustion with or without flames, resulting in heat and mass transfer. Given the complexity of studying all these phenomena simultaneously, the strategy adopted was to separate the different phenomena as much as possible through models and specific experiments. In order to overcome the problem of drying and hydric transfer, all the work was carried out on dry wood. First, specific characterization methods were used to determine the thermal properties of wood and charcoal. These experiments helped to establish behavioral laws for some of these properties, facilitating their integration into a model. Subsequently, an experimental campaign was conducted at the material scale of wood using techniques such as thermogravimetric analysis and differential scanning calorimetry under an inert atmosphere. At this scale, wood is thermally thin, which allowed the development of a kinetic model capable of predicting mass loss, mass loss rate, and heat absorbed or generated by wood during pyrolysis as a function of temperature. Next, an experimental campaign was carried out on wood samples at the scale of the cone calorimeter in an inert atmosphere to validate the 3D pyrolysis model developed to predict wood pyrolysis in the absence of combustion, driven primarily by heat transfer within the material. Finally, tests in an air environment were conducted for a comprehensive modeling of dry wood combustion, which requires a precise characterization of char combustion, the associated heat generated, and the heat flux supplied by the flame
Placet, Vincent. "Conception et exploitation d'un dispositif expérimental innovant pour la caractérisation du comportement viscoélastique et de la dégradation thermique du bois dans des conditions sévères". Phd thesis, Université Henri Poincaré - Nancy I, 2006. http://tel.archives-ouvertes.fr/tel-00116612.
Ainsi, l'objectif majeur de cette thèse est de caractériser le comportement différé du bois vert dans des conditions thermiques et hydriques contrôlées. Un dispositif expérimental parfaitement adapté aux spécificités du bois, et en particulier à son anisotropie et son hygroscopie, a été développé. Cet appareil, appelé WAVET (Environmental Vibration Analyser for Wood) assure la détermination des propriétés viscoélastiques du bois par des essais harmoniques en flexion simple encastrement pour des fréquences comprises entre 5.10-3 Hz et 10 Hz. Dimensionné pour fonctionner jusqu'à des pressions de l'ordre de 5 bars, il permet d'effectuer des essais en milieu anhydre ou saturé pour des températures variant de 0°C à 140°C.
Les résultats expérimentaux collectés à l'aide de cet appareil sur diverses essences tempérées permettent de mettre en évidence l'influence de nombreux paramètres sur les propriétés rhéologiques et notamment au niveau de la température de ramollissement, à savoir l'essence, la direction matérielle, le type de bois (normal/réaction), ou encore la structure anatomique et macromoléculaire.
L'étude de la dégradation thermique du bois saturé en eau dévoile des modifications biochimiques importantes au sein de ce biopolymère. Il apparaît clairement que les propriétés de rigidité et d'amortissement du bois traité thermiquement en milieu aqueux évoluent en fonction de la sévérité du traitement et de la structure native des macromolécules constitutives.
Le, Dirach Jocelyn. "Contribution à l'industrialisation d'un procédé de gazéification". Thesis, Vandoeuvre-les-Nancy, INPL, 2008. http://www.theses.fr/2008INPL024N.
Diversification of energy sources based on renewable energies must contribute to reduce the share of fossil fuels in power generation, in agreement with the European directives which impose to France to generate 21% of its energy from renewable energies before 2010.The present work reported in this manuscript focus on the industrialization of a wood gasification process for the production of heat and electricity. Experiments of wood fast pyrolysis were performed under various experimental conditions (flux density between 0.9 and 6.3 MW/m2, moisture between 0 and 60%) for understanding and analysis of fundamental phenomena related to the gasification of wood. The various products (char, condensible vapours and gases) are recovered and analyzed. The results help to determine the yields of each of the products for various experimental conditions.The numerical modeling of wood pyrolysis phenomena has been achieved on the basis of kinetic data found through literature review and then compared to the experimental results. Even if there is no perfect agreement, orders of magnitude are respected. These models are used as a basis to develop a gasification reactor model for Güssing DFB reactor, including the hydrodynamics description, wood pyrolysis, char gasification, vapours and gases reactions. This model is used to determine the efficiency of the reactor and its various operating parameters
Kohler, Stefanie. "Pyrolyse rapide de biomasses et de leurs constituants. Application à l'établissement de lois prévisionnelles". Thesis, Vandoeuvre-les-Nancy, INPL, 2009. http://www.theses.fr/2009INPL017N/document.
The fast pyrolysis of different types of celluloses, lignins, xylanes as well as different mixtures of these basic compounds and two real biomasses (birch wood and wheat straw) has been studied in an image furnace. The mass loss rates of each of the studied model compounds are very different, but usually higher for cellulose than xylane and higher for xylane than lignins. Lignins begin to react before xylane and cellulose. For a given pyrolysis time, lignins produce more char than xylane. Char formation from cellulose remains insignificant, close to zero. Microgranular cellulose gives mainly rise to vapours and very little gas is formed. Cellulose extracted from birch wood shows an intermediate behaviour between microgranular cellulose and lignins. Production rates of gases are higher than those of vapours for xylan. Regarding the mixtures of these three compounds, an intermediate behaviour can be observed. Birch wood is more reactive than wheat straw. Its pyrolytic behaviour is similar with that of cellulose extracted from birch wood with regard to concerning mass loss rates and vapours formation. A simple additive correlation relying on mass loss rates and products formations rates is elaborated and the results compared to the experimental values. It appears that inorganics play an important role in biomass pyrolysis : the pyrolytic behaviour of wheat straw, a biomass which is rich in inorganics, cannot be described by simple additive correlations. Less significant gaps between expected rates obtained by the correlations and the observed rates obtained by the experiments are found for synthetic mixtures and birch wood. In conclusion, the hypothesis of linear correlations cannot be supported for representing the products formations rates. A complete mathematical model is then developed revealing a non-linear behaviour of the variations of mass losses and products formations. Except for wheat straw, new additive correlations are then determined. The agreement with the experimental results is very satisfying with regard to the measurements accuracies
Haddad, Khouloud. "Etude de la pyrolyse de matériaux biosourcés chimiquement modifiés : Caractérisation des biochars et application agronomique". Thesis, Mulhouse, 2018. http://www.theses.fr/2018MULH2159.
Tunisia produces multitude of dry and wet biomass such as cypress sawdust (CS) and olive mill wastewaters (OMWW), respectively. The main aims of this research work are: i)to study the thermal conversion through slow pyrolysis of the CS impregnated With OMWW and various synthetic mineral solutions (K, Na, Mg and Ca), and ii) to explore the valorisation of the produced biochars as amendments for agricultural soils. The thermogravimetric analyzes (DTG/TG) showed that the impregnation of the CS with the four minerals (K, Na, Mg, Ca) and OMWW induced significant changes in the pyrolysis process. The highest impact was observed for the cellulose degradation in the presence of potassium. Moreover, the pyrolysis temperature as well as the nature of the impregnated mineral on the CS surface affect significantly the yield of the produced biochars and their structures. Regarding the valorisation of the produced biochars, experimental results showed that the biochars generated from the pyrolysis of CS impregnated with OMWW could be used as an efficient fertilizer for agricultural soils. Indeed, it improves by about 36 0/0 the growth of Rye Grass. Furthermore, a relatively high potassium rate was exported to Rye Grass ( (37g Kg-1 ) was registered
Lamarche, Pierre. "Contribution à l'étude expérimentale et à la modélisation de la gazéification étagée de biomasse en lit fixe". Nantes, 2011. http://www.theses.fr/2011NANT2093.
Real alternative with combustion, the energy valorization of the biomass by gasification and CHP answers to the double problem of energy production and wood residues elimination. The work presented in this thesis is related to the development of a dimensioning tool for the continuous fixed bed and external heating pyrolysis reactors integrated into staged gasification process for small and middle power plants (< 500 kWe). This tool allows the prediction of the temperature fields and species concentrations within the bed according to the operating conditions (reactor geometry, wood mass flowrate, wall temperature) and biomass properties (moisture, particle type). Within the framework of this tool development, a staged experimental device made up of a fixed bed and external heating pyrolysis reactor, and of a batch gasification reactor was developed. The obtained transient temperatures profiles on the pyrolysis reactor allowed the validation of a batch pyrolysis model and the determination of a key parameter of the model: the effective thermal conductivity. At the conclusion of this validation, the model was extrapolated for the modeling of continuous pyrolysis, and a parametric study made it possible the limiting parameters identification during pyrolysis with external heating. Lastly, experimental results obtained on the gasification reactor of the experimental device are presented, and recommendations for the improvement of partial oxidation and char reduction stages are given