Thermodynamic and Kinetic Study of Lignocellulosic Waste Gasification

Abstract

In this chapter, the kinetic behavior during the steam gasification of sawdust, plum, and olive pits was investigated by thermogravimetric analysis where theweight loss ismeasured with the temperature variation at different heating rates (5, 10, and 15 K/min). The weight loss and their derivative curves show that the gasification takes place in three visible stages.The kinetic study was carried out using Coats-Redfern methods. The Ginstling-Brounstein model showed better fit. The obtained activation energy values vary between 70 and 100 kJ/ mol for the pyrolysis stage for all studied agro-industrial wastes. On the other hand, a thermodynamic model was proposed to predict the five waste gasification processes, considering the char and tar production. The proposed model allows it to perform a parametric study, analyzing the process variables? effect on the exergetic efficiency. The higher temperatures favor the endothermic reactions as the H2 and CO formation Reactions. Therefore, in the product, moles of H2 and CO increase and consequently the exergy efficiency of the process. Increasing the equivalence ratio value, H2, CO, andCH4 contents decrease; thus the calorific value of the produced gas and the exergetic efficiency decrease. In addition, the CO2 and H2O presences in the syngas composition diminish its calorific value and the exergetic efficiency. Considering the influence of supply steam/biomass ratio, the exergetic efficiency decreases with the growth of this parameter.