Pyrolysis of Waste Plastics: Effect of Heating Rate on Product Yields and Oil Properties

Selecting typical waste plastics, polyethylene (PE), polypropylene (PP) and polyvinyl chloride (PVC), and their mixture PE/PP/PVC as experimental samples, pyrolysis experiments were conducted on tubular furnace reactor at heating rates of 3.7 degrees C.min(-1), 9.0 degrees C.min(-1), 20.6 degrees C.min(-1) and 33.3 degrees C.min(-1) respectively to investigate effect of heating rate on yields of pyrolysis product (cracking oil, cracking gas and residue) and oil properties. The results showed that cracking oil yield was increased, but both the yields of cracking gas and residue were decreased, together with increasing heating rate. The decrease of residue yield was negligible. With the rise of heating rate, calorific value of cracking oil produced from PE and mixture of plastic was decreased and calorific value of oil produced from PP was increased, while that of PVC was decreased at first and increased later. Variations in components distribution of cracking oil generated from different kinds of plastics were different from each other. The results are probably supposed to provide reference for the optimization of pyrolysis process parameters of waste plastics.