Simulation of a thermochemical packed bed reactor developed to treat dried chromated copper arsenate (CCA) impregnated wood waste

Low temperature thermal carbonisation might be the ultimate solution to the growing disposal problem of CCA-treated waste wood. This energy and material recuperating technology is currently in the process of upscaling to an industrial level. In the present study, an axisymmetric two-dimensional simulation model is developed that allows to investigate the char yield and emissions of tars, combustible gases and arsenic during the thermal carbonization of CCA-wood in a moving bed reactor. The influence of hot gas flow rates, wood residence time and the convective heat transfer coefficient on product distribution, metal release and temperature profiles is investigated. An increase of the solid residence time is needed to reach complete wood conversion and better char yields at lower gas flow rates. Arsenic emissions are very low but further research is required in order to predict them more accurately.