Fixed Bed Pyrolysis of Waste Plastic for Alternative Fuel Production

Abstract

The thermochemical conversion of waste plastic using a fixed bed pyrolysis system has been considered in this paper. Favourable properties for pyrolysis conversion, such as high volatile content, elemental composition and thermogravimetric behaviour of waste plastic were investigated by the characterization study reported in this paper. The waste plastic feedstock was pyrolyzed in an externally heated 7 cm diameter and 34 cm high fixed bed reactor. Nitrogen is used as a carrier gas and to maintain the inert condition in the reactor. A biomass source heater and a gravity feed type feeder were used to heat and feed the feedstock into the reactor bed respectively. The pyrolysis products were oily condensate, solid char and gas. The condensate and the char were collected and the gas was flared. The product yields were influenced by the process condition. At an optimum reaction condition of fixed bed temperature of 550ºC, feedstock size of 400-600µm, and 60 min running time the condensate obtained was 70 % of the weight of dry feedstock. The condensate obtained at this optimum condition was analyzed for their properties as an alternative fuel and was compared with other petroleum derived products. The fuel properties of the derived oily condensate compared were physical properties, calorific value, elemental (CHNOS) analysis, and chemical composition using Fourier transfer Infrared (FTIR) spectroscopy.