Thermal Gasification of Polyethylene -Prediction of Product Yield-

Abstract

For the purpose of an effective utilization of plastic wastes, thermal gasification of polyethylene was carried out under atomospheric pressure by using a flow procedure of fixed bed reactor, in which the overheated steam introduced as a heat carrier. By deriving an experimental equation, Ip= Tθ, the product yield was estimated, where IF is intensity function (°Cseca), θ is a reaction temperature (°C), θ is a residence time (sec), and a is constant (-).
Pyrolysis conditions were: temperature, 590∼800°C; residence time, O.6∼6.5 sec; dilution ratio of polymer toward steam, 2.5 (by weight).
Gasification easily proceeded even in a relatively low temperature range, and olefins containing mainly ethylene were obtained in high yield.
When the residence time was 3.2∼3.4 sec And dilution ratio was 2.5∼2.7, the maximum ethylene yield of about 32 wt% at 700°C, the total yield of ethylene, propylene, and 1-butene of about 58 wt% and the total gas yield of about 75 wt% were observed at 650°C.
As a dilution ratio was not so important, operating factors were restricted to reaction temperature and residence time. For a given yield of the product, they were interchangeable. The equation for methane wasoTθ0.04.
As IF correlated with product yields, the product yield could be successfully predicted by an appropriate choice of pyrolysis conditions.