Thermolysis of plastic waste in bench scale fluidized-bed reactor

This thesis was commissioned by VTT Oy, which provides research and innovation services for domestic and international customers and partners. The goal of this Bachelor’s thesis was to study the thermolysis process of plastic waste, compile a review around it and execute test runs with a thermolysis reactor. The review was divided in two parts: back-ground section and the thermolysis of plastics section. Background section included the waste management, current methods for managing the waste and the hierarchy around it. Thermolysis of plastics section reviewed more in depth the thermolysis of plastic waste, including the process reactors, factors affecting the product yield and distribution and finally current commercial technologies for the pyrolysis. Plastic waste originate from multiple sources and have distinct compositions thus waste fractions behave differently in the thermolysis process. The gathered information and data from the test runs was the most significant objective for the project. All of the experiments were performed with a bench-scale (1kg/hr) fluidized-bed pyrolysis reactor. Total of three plastic waste samples were tested plus one with the pure polypropylene as a reference run. Each of the feedstock was tested at three different temperatures. The products were collected as wax, oil, gas and char. The gas was analyzed with a gas chromatograph. The elemental composition of the wax and gas was analyzed in VTT’s laboratories. The results showed that in the thermolysis of plastic waste, the formation of liquid was non-existent and the product was mostly in the form of wax. When the temperature was decreased, the total product yield rose. Also in lower temperatures, the formation of wax in-creased and the formation of non-condensable gases decreased. The best yield in pyrolysis was achieved with the packaging plastic waste when the temperature was 575 °C, being almost 92 wt-%. This thesis provides gathered information package around the thermolysis of plastic waste. The literature part reviewed about the waste management and thermolysis of plastic. Experimental part presented the observations, challenges and data of the test runs and offers behavior of the thermolysis of plastic waste that can be used for further projects for improvements and modeling of the process.