Simulation of a purification plant for pyrolysis gas based on plastic waste

Abstract

This study focuses on exctracting ethylene and propylene from other componenents in the pyrolysis gas mixture of plastic waste. Selective absorption of ethylene and propylene from the gas mixture by using a silver nitrate solution, was selected as a promising technology. A lab scale set-up was built and experimental tests were performed using a model gas mixture. Aspen HYSYSV10 was used to model and simulate the absorption process. The model was validated against experimental data. The validated model was further used to identify improvements for the separation process and increase the recovery of ethylene and propylene. The results from the simulated improved process show that the amount of ethylene and propylene in the product gas could be significantly increased. In the experimental study, only 25% of ethylene and propylene in the feed was captured, whereas the simulation of the improved process indicates that the recovery of the monomers could be almost quantitative (99%). However, the product gas from the separation system contained an undesirable high amount of CO and CO2. These gases act as pollutants of the polyolefin reaction and further studies are needed to obtain pure olefin gases.