Characterisation of slow pyrolysis products from segregated wastes for energy production

The role of pyrolysis is important in the thermal processing of municipal solid wastes, since it decomposes wastes into three types of intermediate products to be collected as fuel feedstock or to be gasified/combusted. In this study, the main products from slow pyrolysis of key segregated waste materials were characterised for mass yield, energy content, elemental composition and chemical compounds. About 200 g of waste wood, cardboard or textile residues were pyrolysed in a small packed bed reactor at a final temperature ranging from 350 to 700 °C with a slow heating rate. The char contained about 38–55% of the energy content in the raw material. The difference in the properties of char between the materials was mainly due to the incombustible fraction that remained in the solid product. The pyrolysis liquids had a gross calorific value of about 10–12 MJ/kg, representing about 20–30% of the energy content in the raw material. The liquids consisted mainly of water and oxygenated compounds such as furans, derivative carboxylic acids and anhydrosugars. Over two thirds of the gases produced were CO and CO2 with increased proportions of CH4 and H2 at high temperatures above 500 °C.