(723e) Prediction of Yields and Composition of Products from Torrefaction

Ireland’s 2015 Energy White Paper proposes the guidelines for a radical transformation in the energy sector in Ireland and a large reduction of CO₂ emissions from 2015 to 2050. Torrefaction is a promising pre-treatment technology, which generates the value-added material from solid waste. In order to improve the properties of briquettes, it is necessary to understand how primary char properties are correlated with feedstock composition and operating conditions since char is formed as a result of the reactions between carbonaceous feedstock matrix, volatiles and inorganic matter. In this study, olive stones were torrefied at various temperatures and holding times in a lab-scale fixed-bed reactor and at one fixed temperature and residence time in a continuous industrial torrefaction unit. The aim of this work is to obtain knowledge about effect of different lignocellulosic compounds and operating conditions on the composition and yields of torrefied biomass. In this study, the kinetic model was validated against the own experimental results. The results of the present work indicated that the catalytic effect of alkali metals on the product yields and composition is significantly less during torrefaction than at temperatures greater than 300°C. The conversion and product distribution of volatiles during torrefaction were related to the hemicellulose transformation. The potential key role of hemicellulose and lignin on the composition and yield of torrefied biomass is highlighted, the issue of torrefaction temperature is discussed. Results showed that the proposed kinetic model for the torrefaction and gas phase reactions is relatively simple and predicts the product yields and composition accurately.