Kinetic modelling of the pyrolysis of biomass and biomass components

Abstract

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 étudié la cinétique de la pyrolyse de matériaux lignocellulosiques dans le but de fournir des modèles cinétiques simples à des fins d'ingénierie. Des données expérimentales obtenues par le biais de techniques d'analyse thermique permettent de croire que la pyrolyse de particules fines (au-dessous de 1 mm) peut ětre contrǒlée par la cinétique de pyrolyse. La vitesse de pyrolyse d'une biomasse donnée peut ětre représentée par la somme des vitesses correspondantes des composants de biomasse principaux (cellulose, lignine, hèmicellulose). La cinétique de chacun de ces composants a été simulée par un schéma cinétique capable de prédire la vitesse de pyrolyse et la perte de poids finale pour un large éventail de paramètres de pyrolyse, y compris de conditions variées de chauffe

Thermal Degradation of Lignocellulosic Fuels: Biopolymers Contribution

“…To have a realistic representation of biopolymer behaviour, it is essential to extract it directly from its source and to perform the analysis on the extracted matter. Similarly to other authors (Koufopanos et al, 1989;Kohler et al, 2005;Miller & Bellan, 1997;Caballero et al, 1996), we made the assumption that the principal components of the fuel contributes to the thermal behaviour of the whole fuel itself and we showed in the present work that the enthalpy reaction of the thermal degradation follows this law. The aim of this work was to quantify the participation of the principal components of the fuel to the reaction enthalpy of thermal degradation of the fuel.…”

“…According to assumption presented in the introduction section, in this work the thermal degradation of forest fuels is viewed as the thermal degradation of the components of the fuel as shown in figure 6. Compared to others studies, (Koufopanos et al, 1989;Kohler et al, 2005;Miller & Bellan, 1997;Caballero et al, 1996) we added the thermal behaviour of the extractives components which play an important role in wildland fires spread (Oasmaa et al, 2003a;Oasmaa et al, 2003b;Pappa et al, 2000). The calculated reaction enthalpy can then be expressed as a combination of reaction enthalpy of each component of the fuel:…”

“…The chemical composition varies from species to species and within the same variety it varies with the botanical origin, age and location in the tree (trunk, branches, crown and roots). In general, previous works refer to different commercial biopolymers (cellulose, xylan to represent hemicellulose…) whose structure is quite different from the native one (Koufopanos et al, 1989;Kohler et al, 2005;Alen et al, 1996;Cozzani et al, 1997). To have a realistic representation of biopolymer behaviour, it is essential to extract it directly from its source and to perform the analysis on the extracted matter.…”

Theoretical Investigations of the Effects of Isothermal and Non-isothermal Heating Conditions on the Pyrolysis Kinetics of Biomass Particle

“…During the non-isothermal condition, pyrolysis temperature is progressively increased with increasing heating time using a specified heating rate, while isothermal condition maintains a selected constant temperature in a pyrolyzing chamber. In describing pyrolysis behaviour of biomass particles under such conditions a number of pyrolysis kinetic studies and models have been proposed (Gronli et al (2002); Guo and Lau (2001) ;Koufopanos et al (1989); Vamvuka et al (2003); Williams and Besler (1994); Thurner and Mann (1981); Font et al (1990); Di Blasi and Russo (1994), Boroson et al (1989)). Babu and Chaurasia (2002) studied numerically the effects of heating conditions, heating rates and order of the kinetic reactions on wood pyrolysis using the two-step model of Koufopanos et al In the study of pyrolysis reaction temperature, Sheth and Babu (2006) presented that pyrolysis in wood is typically initiated at 200°C and lasts till 450-500°C, depending on the species of wood.…”

Performance Analysis of a Woodchip Downdraft Gasifier: Numerical Prediction and Experimental Validation

“…To pursue the said target, it is necessary, as a first step, to clearly define the level of accuracy and detail which is expected from the theoretical model. Several approaches aim to assess just the final composition of chemical equilibrium [1][2][3][4][5][6], while others, which follow methods based on chemical kinetics, try to distinguish a sequence of zones along the gasifier characterized by different processes [7][8][9][10]. As discussed rather thoroughly in Ref.…”