Processes for the Thermal Degradation of Plastic Wastes

The fluidized bed plants developed by Kaminsky et al. have been used for the conversion of a variety of plastic mixtures. In a recent work,99 the results obtained in the conversion of two different plastic wastes at temperatures of 638, 690 and 735 °C were reported. The raw mixture consisted mainly of polyolefins (65-79%), polystyrene (4-30%) and polyvinyl chloride (4-5%). The following fractions were derived from the pyrolysis of these materials gases (35 42.9%), oils (41-51.8%), residue (5.8-14.3%) and soot (2.2-5.4%). The gases were mainly methane, ethylene and propylene, with a certain concentration of CO and C02 due to the presence of oxygen in the feed material. At the lowest pyrolysis temperature the oil produced contains a high proportion of 

Schematic diagram of a pilot plant for the thermal conversion of plastic wastes with an internally circulating fluidized bed reactor.30 

On the other hand, the non-condensable gases consist mainly of hydrogen, methane, ethane and ethylene, with minor amounts of C3 and C4 hydrocarbons, in addition to pollutants such as NH3, HCN and HC1. The latter must be removed by various treatments. 

Degradative extrusion of different plastic mixtures causes a significant 

Viscosity of the products obtained by degradative extrusion of plastic mixtures as a function of the shear rate.1 

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