SFGP 2007 - Two-Step Process of Thermo-Chemical Conversion of Wood Waste Contaminated by Aminoplast Resins

Abstract

The aim of this study is to develop a two-steps process of thermal valorisation of wood waste containing urea-formaldehyde and melamine-formaldehyde resins such as wood board or laminated flooring. The first step of the process known as "refinement" is a low temperature pyrolysis between 250°C and 300°C which aims to remove nitrogen thermally. This step is studied by IRTF spectrometry. Ultimate analysis enables the assessment of the efficiency of the process in terms of nitrogen removal. It is shown that around 68 wt% of nitrogen can be removed during this first stage and that a 250°C treatment gives the best results in terms of energy recovery. The second step is a fast pyrolysis of the residue of the first step which aims to produce combustible gas. Three temperatures of pyrolysis are studied (800°C, 900°C and 1000°C) by GC-TCD analysis. It is shown that the temperature of the pyrolysis has an influence on the volume of gas produced and on its Low Heating Value. The best results are obtained with the 1000°C pyrolysis which produces a higher volume of gas and gives the best energetic efficiency. The residual char after fast pyrolysis step still contains energy and nitrogen. Its combustion would improve the energetic efficiency of the process but a conversion into an activated char has to be considered to improve the economic efficiency of such a type of waste disposal process.