New energy value chain through pyrolysis of hospital plastic waste

Abstract

In this paper, the evolution in thermochemical behaviours of hospital plastic wastes and changes in chemical composition and characteristics of pyrolysis liquid products have been investigated by using different fixed bed reactor scales. The main objective is to identify the critical technical parameters enabling thermochemical process adaptation in function of raw materials chemical structure, with the aim of maximising the yield of condensable fraction and optimising its energetic properties related to internal combustion engines.It is a step-by-step procedure using three reactor capacity levels, which allows various aspects approach of thermochemical process development from the evaluation of global reaction kinetic parameters to the measurement of physicochemical properties of the final pyrolysis products. In order to reduce the gas and solid fractions with corresponding increasing of condensable products, the transposition of thermal and kinetic information provided by thermogravimetric analysis (TGA) to larger reactors is used to control of process parameters. In this experimental work the mass of samples increases from 0.05 g in the thermogravimetric analyser to 600 g in the bench scale reactor.Gas-chromatography techniques have been used to identify the chemical composition of gases (GC/TCD) and liquids (GC/FID-MS).It was established that changing the reactor scale does not result in significant differences in pyrolysis product distribution, neither in gas composition. On the other hand, the aspect and the quality of condensable fraction display a high variability. Also, the energy contained in the final valuable pyrolysis product was compared with the energy demand during the thermochemical transformation in order to evaluate the energy efficiency of the process.