Thermodynamic and Kinetic Study of Lignocellulosic Waste Gasification

ROSA RODRÍGUEZ; GERMÁN MAZZA; MARCELO ECHEGARAY; ANABEL FERNANDEZ BRIZUELA ; DANIELA ZALAZAR GARCÌA

Gasification for Low-grade Feedstock

IntechOpen

Lugar: Rijeka; Año: 2018; p. 57 - 77

In this chapter, the kinetic behavior during the steamgasification of sawdust, plum, andolive pits was investigated by thermogravimetricanalysis where theweight loss ismeasuredwith the temperature variation at different heatingrates (5, 10, and 15 K/min). The weightloss and their derivative curves show that thegasification takes place in three visible stages.The kinetic study was carried out using Coats-Redfernmethods. The Ginstling-Brounsteinmodel showed better fit. The obtained activationenergy values vary between 70 and 100 kJ/mol for the pyrolysis stage for all studiedagro-industrial wastes. On the other hand, athermodynamic model was proposed to predict the fivewaste gasification processes, consideringthe char and tar production. The proposed model allowsit to perform a parametricstudy, analyzing the process variables? effect on the exergetic efficiency. Thehigher temperaturesfavor the endothermic reactions as the H2 and CO formation reactions. Therefore, inthe product, moles of H2 and CO increase and consequently the exergy efficiency of theprocess. Increasing the equivalence ratio value, H2, CO, and CH4 contents decrease;thus thecalorific value of the produced gas and the exergeticefficiency decrease. In addition, the CO2and H2O presences in thesyngas composition diminish its calorific value and the exergeticefficiency. Considering the influence of supplysteam/biomass ratio, the exergetic efficiencydecreases with the growth of this parameter.