Kinetics of the thermal degradation of Erica arborea by DSC: Hybrid kinetic method

The scope of this work was the determination of kinetic parameters of the thermal oxidative degradation of a Mediterranean scrub using a hybrid method developed at the laboratory. DSC and TGA were used in this study under air sweeping to record oxidative reactions. Two dominating and overlapped exothermic peaks were recorded in DSC and individualized using an experimental and numerical separation. This first stage allowed obtaining the enthalpy variation of each exothermic phenomenon. In a second time, a model free method was applied on each isolated curve to determine the apparent activation energies. A reactional kinetic scheme was proposed for the global exotherm composed of two independent and consecutive reactions. In fine mean values of enthalpy variation and apparent activation energy previously determined were injected in a model fitting method to obtain the reaction order and the preexponential factor of each oxidative reaction. We plan to use these data in a sub-model to be integrated in a wildland fire spread model

Microvawe pyrolysis of biomass: control of process parameters for high pyrolysis oil yields and enhanced oil quality

The oil yield and quality of pyrolysis oil from microwave heating of biomass was established by studying the behaviour of Larch in microwave processing. This is the first study in biomass pyrolysis to use a microwave processing technique and methodology that is fundamentally scalable, from which the basis of design for a continuous processing system can be derived to maximise oil yield and quality. It is shown systematically that sample size is a vital parameter that has been overlooked by previous work in this field. When sample size is controlled the liquid product yield is comparable to conventional pyrolysis, and can be achieved at an energy input of around 600 kWh/t. The quality of the liquid product is significantly improved compared to conventional pyrolysis processes, which results from the very rapid heating and quenching that can be achieved with microwave processing. The yields of Levoglucosan and phenolic compounds were found to be an order of magnitude higher in microwave pyrolysis when compared with conventional fast pyrolysis. Geometry is a key consideration for the development of a process at scale, and the opportunities and challenges for scale-up are discussed within this paper

Potential applications of nanotechnology in thermochemical conversion of microalgal biomass

The rapid decrease in fossil reserves has significantly increased the demand of renewable and sustainable energy fuel resources. Fluctuating fuel prices and significant greenhouse gas (GHG) emission levels have been key impediments associated with the production and utilization of nonrenewable fossil fuels. This has resulted in escalating interests to develop new and improve inexpensive carbon neutral energy technologies to meet future demands. Various process options to produce a variety of biofuels including biodiesel, bioethanol, biohydrogen, bio-oil, and biogas have been explored as an alternative to fossil fuels. The renewable, biodegradable, and nontoxic nature of biofuels make them appealing as alternative fuels. Biofuels can be produced from various renewable resources. Among these renewable resources, algae appear to be promising in delivering sustainable energy options. Algae have a high carbon dioxide (CO2) capturing efficiency, rapid growth rate, high biomass productivity, and the ability to grow in non-potable water. For algal biomass, the two main conversion pathways used to produce biofuel include biochemical and thermochemical conversions. Algal biofuel production is, however, challenged with process scalability for high conversion rates and high energy demands for biomass harvesting. This affects the viable achievement of industrial-scale bioprocess conversion under optimum economy. Although algal biofuels have the potential to provide a sustainable fuel for future, active research aimed at improving upstream and downstream technologies is critical. New technologies and improved systems focused on photobioreactor design, cultivation optimization, culture dewatering, and biofuel production are required to minimize the drawbacks associated with existing methods. Nanotechnology has the potential to address some of the upstream and downstream challenges associated with the development of algal biofuels. It can be applied to improve system design, cultivation, dewatering, biomass characterization, and biofuel conversion. This chapter discusses thermochemical conversion of microalgal biomass with recent advances in the application of nanotechnology to enhance the development of biofuels from algae. Nanotechnology has proven to improve the performance of existing technologies used in thermochemical treatment and conversion of biomass. The different bioprocess aspects, such as reactor design and operation, analytical techniques, and experimental validation of kinetic studies, to provide insights into the application of nanotechnology for enhanced algal biofuel production are addressed

MODELLING OF THE PYROLYSIS OF LIGNOCELLULOSIC MATERIALS

THE PYROLYSIS OF VARIOUS LIGNOCELLULOSIC MATERIALS WAS STUDIED IN ORDER TO MODELIZE THE KINETICS OF BOTH PRIMARY AND SECONDARY REACTIONS AS ALSO TRANSPORT PHENOMENA. MODELLING WAS BASED ON EXPERIMENTAL DATA OBTAINED BY MEANS OF THERMAL ANALYSIS TECHNIQUES. THE MODEL OF INTERMEDIATE STEP COMPOSITION IS CORRELATED TOTHE PYROLYSIS RATE BY MEANS OF A SIMPLE ADDITIVE MODEL. USING BOTH THE ADDITIVE MODEL AND THE MODEL OF INTERMEDIATE STEP IT IS POSSIBLE TO PREDICT THE PYROLYSIS RATE OF DIFFERENT LIGNOCELLULOSIC MATERIAL UNDER DIFFERENT HEATING CONDITIONS. A MODEL INVOLVING ALSO THE SECONDARY INTERACTIONS BETWEEN CHARCOAL AND VOLATILES WAS SUGGESTED. THE TRANSPORT PHENOMENA AND THE CHEMICAL REACTIONS ARE DESCRIBED BY MEANS OF A GENERAL MODEL INVOLVING THE HEAT TRANSMISSION BALANCE IN APYROLYZING SOLID PARTICLE AND THE EQUATION OF PYROLYSIS RATE. THE HEAT BALANCEINCLUDES A TERM, WHICH REPRESENTS THE HEAT FLOW DUE TO REACTION HEAT. THE HEATOF THE PYROLYSIS REACTIONS CAN BE REPRESENTED BY TWO VALUES: AN ENDOTHERMIC ONE (FOR LOW CONVERSION) AND AN EXOTHERMIC ONE (FOR HIGH CONVERSION).ΜΕΛΕΤΗΘΗΚΕ Η ΠΥΡΟΛΥΣΗ ΔΙΑΦΟΡΩΝ ΛΙΓΝΟΚΥΤΤΑΡΙΝΙΚΩΝ ΥΛΙΚΩΝ ΜΕ ΣΚΟΠΟ ΤΗ ΜΟΝΤΕΛΟΠΟΙΗΣΗ ΤΗΣ ΚΙΝΗΤΙΚΗΣ ΤΩΝ ΠΡΩΤΟΓΕΝΩΝ ΚΑΙ ΔΕΥΤΕΡΟΓΕΝΩΝ ΧΗΜΙΚΩΝ ΔΡΑΣΕΩΝ ΚΑΘΩΣ ΚΑΙ ΤΩΝ ΦΑΙΝΟΜΕΝΩΝ ΜΕΤΑΦΟΡΑΣ. Η ΜΟΝΤΕΛΟΠΟΙΗΣΗ ΣΤΗΡΙΧΘΗΚΕ ΣΕ ΠΕΙΡΑΜΑΤΙΚΑ ΔΕΔΟΜΕΝΑ ΠΟΥ ΕΛΗΦΘΗΣΑΝ ΑΠΟ ΠΕΙΡΑΜΑΤΑ ΘΕΡΜΙΚΗΣ ΑΝΑΛΥΣΗΣ. ΤΟ ΜΟΝΤΕΛΟ ΕΝΔΙΑΜΕΣΟΥ ΣΤΑΔΙΟΥ ΠΕΡΙΓΡΑΦΕΙ ΤΟ ΡΥΘΜΟ ΠΥΡΟΛΥΣΗΣ ΤΩΝ ΚΥΡΙΩΝ ΣΥΣΤΑΤΙΚΩΝ ΤΗΣ ΒΙΟΜΑΖΑΣ. Η ΣΥΣΤΑΣΗ ΤΗΣ ΒΙΟΜΑΖΑΣ ΣΥΝΔΕΕΤΑΙ ΜΕ ΤΟ ΡΥΘΜΟ ΠΥΡΟΛΥΣΗΣ ΜΕΣΩ ΕΝΟΣ ΑΠΛΟΥ ΑΘΡΟΙΣΤΙΚΟΥ ΜΟΝΤΕΛΟΥ. Η ΣΥΝΔΥΑΣΜΕΝΗ ΧΡΗΣΗ ΑΘΡΟΙΣΤΙΚΟΥ ΜΟΝΤΕΛΟΥ ΚΑΙ ΜΟΝΤΕΛΟΥ ΕΝΔΙΑΜΕΣΟΥ ΣΤΑΔΙΟΥ ΠΡΟΒΛΕΠΕΙ ΙΚΑΝΟΠΟΙΗΤΙΚΑ ΤΟ ΡΥΘΜΟ ΠΥΡΟΛΥΣΗΣ ΔΙΑΦΟΡΩΝ ΛΙΓΝΟΚΥΤΤΑΡΙΝΙΚΩΝ ΥΛΙΚΩΝ ΚΑΙ ΣΕ ΔΙΑΦΟΡΕΤΙΚΕΣ ΣΥΝΘΗΚΕΣ ΘΕΡΜΑΝΣΗΣ. ΠΑΡΑΛΛΗΛΑ ΠΡΟΤΑΘΗΚΕ ΚΑΙ ΕΝΑ ΜΟΝΤΕΛΟ ΓΙΑ ΤΗΝ ΠΥΡΟΛΥΣΗ ΤΟΥ ΞΥΛΟΥ ΠΟΥ ΣΥΜΠΕΡΙΛΑΜΒΑΝΕΙ ΤΙΣ ΑΝΤΙΔΡΑΣΕΙΣ ΔΕΥΤΕΡΟΓΕΝΩΝ ΑΛΛΗΛΕΠΙΔΡΑΣΕΩΝ ΚΑΡΒΟΥΝΟΥ ΚΑΙ ΠΤΗΤΙΚΩΝ. Η ΣΥΝΔΥΑΣΜΕΝΗ ΕΠΙΔΡΑΣΗ ΦΑΙΝΟΜΕΝΩΝ ΜΕΤΑΦΟΡΑΣ ΚΑΙ ΧΗΜΙΚΩΝ ΔΡΑΣΕΩΝ ΠΕΡΙΓΡΑΦΕΤΑΙ ΑΠΟ ΕΝΑ ΓΕΝΙΚΕΥΜΕΝΟ ΜΟΝΤΕΛΟ ΠΟΥ ΠΕΡΙΛΑΜΒΑΝΕΙ ΤΟ ΙΣΟΖΥΓΙΟ ΘΕΡΜΟΤΗΤΑΣ ΣΕ ΕΝΑ ΠΥΡΟΛΥΟΜΕΝΟ ΣΤΕΡΕΟ ΣΩΜΑΤΙΔΙΟ ΚΑΙ ΤΗΝ ΕΞΙΣΩΣΗ ΤΟΥ ΡΥΘΜΟΥ ΠΥΡΟΛΥΣΗΣ. ΣΤΟ ΙΣΟΖΥΓΙΟ ΥΠΑΡΧΕΙ ΚΑΙ ΕΝΑΣ ΟΡΟΣ ΠΟΥ ΑΝΑΦΕΡΕΤΑΙ ΣΤΗ ΡΟΗ ΘΕΡΜΟΤΗΤΑΣ ΛΟΓΩ ΧΗΜΙΚΩΝ ΑΝΤΙΔΡΑΣΕΩΝ. Ο ΘΕΡΜΟΤΟΝΙΣΜΟΣ ΤΟΥΣ ΜΠΟΡΕΙ ΝΑ ΑΝΤΙΠΡΟΣΩΠΕΥΘΕΙ ΑΠΟ ΔΥΟ ΤΙΜΕΣ:ΜΙΑ ΕΝΔΟΘΕΡΜΗ (ΧΑΜΗΛΕΣ ΜΕΤΑΤΡΟΠΕΣ) ΚΑΙ ΜΙΑ ΕΞΩΘΕΡΜΗ ΤΙΜΗ (ΥΨΗΛΕΣ ΜΕΤΑΤΡΟΠΕΣ)

PYROLYSIS, A PROMISING ROUTE FOR BIOMASS UTILIZATION

The pyrolysis of biomass is a thermal treatment which results in the production of char, liquid and gaseous products. In this laboratory the pyrolysis process has been studied experimentally using apparatus of different scales. In particular, the influence of the main process parameters on the yields and characteristics of the products has been investigated. On the basis of these results the differences between convertional and fast pyrolysis can be discussed. The most attractive product of conventional pyrolysis is charcoal, as the handling and use of bio-oil presents some problems due to its characteristics. The pyrolysis gas is a medium BTU gas and can be easily burnt. Fast pyrolysis minimizes charcoal production. This process gives as the main product a high yield of a medium BTU gas rich in hydrogen and carbon monoxide. The feasibility of the process on an industrial scale is discusse

Kinetic modelling of the pyrolysis of biomass and biomass components

The kinetics of the pyrolysis of lignocellulosic materials was studied with a view of providing simple kinetic models for engineering purposes. Experimental data obtained by means of thermal analysis techniques suggest that the pyrolysis of fine particles (below 1 mm) can be considered to be controlled by pyrolysis kinetics. The rate of pyrolysis of one biomass type can be represented by the sum of the corresponding rates of the main biomass components (cellulose, lignin, hemicellulose). The kinetics of each of these components was simulated by a kinetic scheme capable of predicting the pyrolysis rate and the final weight-loss for a wide range of pyrolysis parameters including various heating conditions. On a \ue9tudi\ue9 la cin\ue9tique de la pyrolyse de mat\ue9riaux lignocellulosiques dans le but de fournir des mod\ue8les cin\ue9tiques simples \ue0 des fins d'ing\ue9nierie. Des donn\ue9es exp\ue9rimentales obtenues par le biais de techniques d'analyse thermique permettent de croire que la pyrolyse de particules fines (au-dessous de 1 mm) peut \u11btre contr\u1d2l\ue9e par la cin\ue9tique de pyrolyse. La vitesse de pyrolyse d'une biomasse donn\ue9e peut \u11btre repr\ue9sent\ue9e par la somme des vitesses correspondantes des composants de biomasse principaux (cellulose, lignine, h\ue8micellulose). La cin\ue9tique de chacun de ces composants a \ue9t\ue9 simul\ue9e par un sch\ue9ma cin\ue9tique capable de pr\ue9dire la vitesse de pyrolyse et la perte de poids finale pour un large \ue9ventail de param\ue8tres de pyrolyse, y compris de conditions vari\ue9es de chauffe

Modelling of the pyrolysis of biomass particles. Studies on kinetics, thermal and heat transfer effects

The present work provides a rationally-based model to describe the pyrolysis of a single solid particle of biomass. As the phenomena governing the pyrolysis of a biomass particle are both chemical (primary and secondary reactions) and physical (mainly heat transfer phenomena), the presented model couples heat transport with chemical kinetics. The thermal properties included in the model are considered to be linear functions of temperature and conversion, and have been estimated from literature data or by fitting the model with experimental data. The heat of reaction has been found to be represented by two values: one endothermic, which prevails at low conversions and the other exothermic, which prevails at high conversions. Pyrolysis phenomena have been simulated by a scheme consisting of two parallel reactions and a third reaction for the secondary interactions between charcoal and volatiles. The model predictions are in agreement with experimental data regarding temperature and mass-loss histories of biomass particles over a wide range of pyrolysis conditions. On pr\ue9sente dans cet article un mod\ue8le s'appuyant sur des bases rationnelles pour d\ue9crire la pyrolyse d'une particule solide simple de biomasse. Consid\ue9rant que les ph\ue9nom\ue8nes gouvernant la pyrolyse de la particule de biomasse sont \ue0 la fois chimiques (r\ue9actions primaires et secondaires) et physiques (principalement des ph\ue9nom\ue8nes de transfert de mati\ue8re), le mod\ue8le pr\ue9sent\ue9 couple le transport de chaleur avec la cin\ue9tique chimique. Les propri\ue9t\ue9s thermiques incluses dans le mod\ue8le sont consid\ue9r\ue9es comme \ue9tant des fonctions lin\ue9aires de la temp\ue9rature et de la conversion et ont \ue9t\ue9 estim\ue9es \ue0 partir de donn\ue9es pubi\ue9es dans la litt\ue9rature ou en adaptant le mod\ue8le aux donn\ue9es exp\ue9rimentales. On a trouv\ue9 que la chaleur de la r\ue9action \ue9tait repr\ue9sent\ue9e par deux valeurs: une valeur endothermique qui pr\ue9domine \ue0 de faibles conversions et une valeur exothermique qui pr\ue9domine \ue0 des conversions \ue9lev\ue9es. Les ph\ue9nom\ue8nes de pyrolyse ont \ue9t\ue9 simul\ue9s par un sch\ue9ma comportant deux r\ue9actions parall\ue8les et une troisi\ue8me r\ue9action pour les interactions secondaires charbon-volatils. Les pr\ue9dictions du mod\ue8le montrent un bon accord avec les donn\ue9es exp\ue9rimentales sur la temperature et l'histoire de la perte massique des particules de biomasse pour une vaste gamme de conditions de pyrolys