Municipal waste pyrolysis: Chlorine capture by addition of calcium and sodium-based sorbents

Now in the case of the municipal waste treatments, it is widely accepted that pyrolysis can be an attractive alternative to incineration, if the process is followed by an energy valorisation of the solid residue(1,2). During pyrolysis of PVC containing waste, chlorine is evolved mostly in pyrolytic gases, mainly as HCl3,4. When lignin is present in the waste, a large proportion of the chlorine is entrapped in the solid char, less HCl being emitted(5). When basic sorbents are added during pyrolysis, it is possible to trap the chlorine under leachable form in the char. The purpose of this work is to analyse the extrapolation of laboratory scale experiments to pilot scale facilities and to evaluate efficiency of the chlorine trapping during the pyrolysis of wood-PVC mixtures in a rotating kiln. When the char during pyrolysis entraps the chlorine under leachable form, it can be eliminated before further use. It is important to guide the chlorine either in the gas or in the char outputs by selected additions, in order to fit with the requirements of the fuels end users.