Verfahren und Vorrichtung zur thermischen Depolymerisation von Kunststoffen

摘要

The invention relates to a process and an apparatus for the thermal depolymerisation of plastics, in particular plastics in the form of sorted or unsorted polymer waste from industrial production or from domestic refuse. Such plastics are, for ecological reasons, subjected to physical chemical recycling by comminution to give low-molecular-weight fragments. In accordance with the invention, the polymer feed is introduced into a reaction space, where it is depolymerised with supply of heat, where the thermal depolymerisation gives volatile hydrocarbons and low-molecular-weight fragments, which are removed from the reaction space in gas form, circulation of the bottom phase obtained from the plastics via a heating circuit with reboiler taking place in the reaction space and a liquid and optionally partly solid residue from the thermal depolymerisation being removed from the bottom product of the reaction space. These volatile hydrocarbons and low-molecular-weight fragments are predominantly produced in the form of relatively short-chain oligomers. The plastics can be comminuted or warmed as granules or in suspension and melted. The warming and melting can be carried out at least partly in a pretreatment vessel. The comminuted, granulated or suspended polymers are advantageously mixed with a sub-stream of the melt from the reaction space and fed into the pretreatment vessel. Depolymerisation in the reaction space is carried out at a pressure of from 0.01 to 20 bar absolute and at a temperature of from 300 to 900 DEG C.