The aim of this study is to research the mechanism of dechlorination for low-temperature pyrolysis process not only by establishing the material and calorific balance at the first stage of the two-stage fluid-ized-bed waste incinerator but also by revealing the behavior of chlorine towards products formed in the pyrolysis. The pyrolysis experiments have been performed using wood chips containing poly (vinyl chloride) in a 5: 1 weight ratio as a model refuse-feed. The feed is pyrolyzed with and without catalyst (disposable iron sulfide catalyst), as well as under the presence of low oxygen concentration (5.7vol%) at 360-420°C. The acidic and acid-free fractions separated by the treatment with an anion exchange resin from tar component are characterized by means of spectroscopic techniques (FT-i.r., 1H-NMR and 13C-NMR) and ultimate analysis, comparing to those from tar components formed by the pyrolysis of six different kinds of hydrocarbons and poly (vinyl chloride).
The results show that; (1) Calorific value of char retains more than 40% of the starting feed, which exceeds the process target for calorific balance between the first and second stage of the total incineration process.(2) More than 95% of chlorine involved in the feed is removed during pyrolysis and the dechlori-nated char component (Cl content: 0.4-0.8wt%) could be transferred into the second stage for the total system.(3) The presence of the catalyst in the pyrolysis plays an important role in the reduction of chlorophenols formed in the low-temperature pyrolysis process.
