Thermodynamic and Kinetic Study of Lignocellulosic Waste Gasification

RODRIGUEZ, ROSA; MAZZA, GERMAN; ECHEGARAY, MARCELO; FERNANDEZ, ANABEL; ZALAZAR, DANIELA

Gasification for Low-grade Feedstock

IntechOpen Limied

Lugar: Londres; Año: 2018; p. 57 - 77

In this chapter, the kinetic behavior during the steam gasification of sawdust, plum, and olivepitswasinvestigatedbythermogravimetricanalysiswheretheweightlossismeasured with the temperature variation at different heating rates (5, 10, and 15 K/min). The weight loss andtheir derivative curvesshowthatthe gasification takesplace in threevisible stages. The kinetic study was carried out using Coats-Redfern methods. The Ginstling-Brounstein modelshowedbetterfit.The obtainedactivationenergyvaluesvarybetween70and100 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, consideringthecharandtarproduction.The proposed modelallowsittoperformaparametric 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.Increasingtheequivalenceratiovalue,H2,CO,andCH 4 contentsdecrease;thusthe calorificvalueoftheproducedgasandtheexergeticefficiencydecrease.Inaddition,theCO2 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 thegrowthof thisparameter.