Pyrolysis of plastic waste and scrap tyres in a fluid bed reactor

Abstract

An outline of laboratory-scale investigations of pyrolysis is followed by a description of pilot-scale experiments designed to exploit the raw material content of polymeric substances rather than their heating value merely as fuels. Dependent on the feed material, gaseous products (40–60 wt.%, e.g. hydrogen, methane, ethylene, ethane) as well as liquid products (40–60 wt.%, mainly simple aromatics) are obtained. The gas is sufficient to heat the process.

Fluid sand beds are surprisingly insensitive to the unit size of the feed material, so that scrap tyres can be pyrolyzed as a whole to avoid the cost of size reduction. Carbon soot and fillers are separated in a cyclone and metal pieces can be removed from the inclined bottom of the reactor. Results for a 2 Mg/day pilot plant are presented and a preview of a 4000 Mg/year plant is given, for which cost—benefit calculations are compared with those of some other scrap tyre pyrolysis processes.