Pyrolysis Process Studies for Post Consumer Polyethene Waste Conversion and Upgrading of the Pyrolysis Oil

There is a rising concern on the extensive environmental impacts resulting from unsustainable methods for management of post consumer waste plastics (PCPW) in Kenya. This study was conducted on conversion of PCPW into fuel gas and oils. Low Density Polythene (LDPE), High Density polythene (HDPE) and Polypropylene (PP) were heated in a locally assembled pyrolysis reactor at temperatures ranging between 200-500 C and with heating rates of 5-15 C / minute. Fractionation was conducted to refine the resultant crude oil into petrol at 150 oC and diesel at 350 oC.359.64 g 1.67, 348.21 g 0.97 and 301.22 g 1.5 of crude oil for 500 g of HDPE, LDPE and PP resulted respectively. Diesel, petrol char and wax yields obtained were (72 %1.50, 70 %1.32, 60 %1.67) (6 %0.46, 8.3 %0.37, 6 %0.54), (1 %0.67, 5 %1.21, 2 %0.57) and (1 %0.27, 1.03 %0.42, 1 %0.32) grams for HDPE, LDPE and PP respectively. Mean values for petrol and diesel yields for HDPE and LDPE did not differ significantly with (t observed less than t calculated) for paired T-test (at 95 % confidence level). Over 90 %1.87 conversion of plastic waste into fuel products was achieved. The plant was economically viable with an energy consumption of less than 5 % of the total energy in 0.5 kg of waste plastics.