THERMOLYSIS OF PLASTIC WASTE AND COMPOSITES-A METHOD FOR ENERGY VALORISING AND/OR REINFORCED MATERIALS RECYCLING

摘要

Feedstock recycling describes the process where polymers are de-composed by chemical and/or thermal methods to simple precursor molecules. These can then be used either in plastics production or as basic chemical feedstock for other industries. We propose an integrated plant, where the gases resulted from plastics thermolysis are condensed and the liquid obtained is burned into diesel engine, after a potential distillation process. Certainly, in the case of materials that give a large percent of light gaseous products during thermolysis process, these gases can be used directly into gas-engine. The system predicts that burned gases from the engine give the necessary energy for thermal processes, at least for distillation. By pyrolysis process, plastics are separated into liquid products (oil), gases and char residue. Recovery ratio and characteristics of pyrolysis products differ depending on the types of plastics and decomposing temperature. The aim of the present study is to describe an integrated power system where the fuel is obtained in a process based on non-catalytic pyrolysis of plastic waste materials and the necessary temperature for this process is assured by the heat of burned gases. In function of chemical composition of the plastic waste that determines yields of pyrolysis products many technological system can be proposed. We are looking on pyrolysis not only as a intermediary step in low to medium scale power devices, but also as a technique that is able to reduce a bulky, high polluting industrial waste while producing energy or valuable chemical compounds. Different types of plastics and composites were evaluated in our experiments. The waste plastics of poly-hydrocarbons composites from cars manufacturing were those used for our calculations. They were chosen especially for their total conversion during the applied thermal process - at 550°C as final temperature, under a specific heat rate, the total conversion of plastic into organic compounds were about 95 % (wt), whence liquid part is about 75 % (wt) and gaseous, 25 %. The product yields of oil, gas and solid residue were determined together with a detailed composition of the derived oils and carbonaceous residue. For that, elemental analysis using a C, H, N, S-O Analyser (Flash EA 1112Series) was considered. The liquid part was distilled and the obtained product was analysed. It has a very good heating value (LHV = 58600 kJ/kg) and a low cinematic viscosity (6.25 cSt at 20°C) As a result of our experimental work, we propose the development and after that the implementation of an integrated thermolysis combined cycle as the final concept of a plastic waste-to-electricity system.