Thermal decomposition behavior, characterization and evaluation of pyrolysis products of agricultural wastes

• Published in: Journal of the Energy Institute Vol. 91; no. 6; pp. 951 - 961
• Main Authors: Sfakiotakis, Stelios, Vamvuka, Despina
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.12.2018
• Subjects: Biochars; Grape residues; Olive kernel; Olive tree pruning; TG/MS; Olive tree pruning; TG/MS; Olive kernel; Biochars; Grape residues
• ISSN: 1743-9671
• DOI: 10.1016/j.joei.2017.09.001

Thermal decomposition behavior during pyrolysis, the composition and the physicochemical characteristics of the pyrolysis products were studied for four agricultural wastes from Southern Greece. These wastes are produced in abundance in the Mediterranean Region but still remain relatively unexploited, while there is also lack or little relevant scientific information. Pyrolysis process for the examined samples was studied using a TGA analyzer and a properly tested and calibrated TG/MS setup, at a heating rate of 10 °C/min up to 850 °C. Determination of important quantitative parameters of pyrolysis as a function of temperature, on an instantaneous or integral basis, and correlation of the evolved gas results with the degradation of pseudocomponents of raw biomass was made possible. The average higher heating value of the pyrolysis light gases was found to be in a satisfactory for energy purposes range of 11.2–14.4 MJ/Nm3. Furthermore, biochars produced at 450, 550 and 650 °C in a fixed bed reactor were found to exhibit calorific value ranging from 20.1 to 28.7 MJ/kg and structural stability. They were also found to have a high nutrients content and below limits or negligible heavy metals content for soils applications, regardless of production temperature. •TGA/DTG/MS and fixed bed reactor experiments for pyrolysis of agro-residues.•Biochars exhibit satisfactory nutrient content, below limits heavy metals content.•Quantitative analysis of evolved light gases and tar.•Correlation of TG/MS results with a pyrolysis kinetic model.•Satisfactory calorific value of light gases evolved from pyrolysis.