Investigation on the heat transfer and product characteristics of waste PCB recycled by a novel pilot-scale pyrolysis furnance

Abstract

Printed circuit boards (PCBs) is a major constituent of the waste electric and electronic equipment, which represents a rapidly growing disposal problem worldwide. In order to achieve large-scale treatment of PCB, this work designed an innovative pilot-scale fixed-bed pyrolysis experiment system and proposed detailed on-site temperature measurements to quantify the impact and the delays of the temperature acceleration process. The large heat absorption of the pyrolysis reaction causes low heat transfer efficiency and significant temperature gradient along the vertical of the polit-scale furnance. Furthermore, X-ray fluorescence spectrometer, scanning electron microscope, gas chromatography–mass spectrometer and ion chromatograph were applied for the analysis of the pyrolysis product characteristics. The proportions of the phenolic compounds are 69.23%, 68.46% and 56.17% corresponding to the temperatures of 350 °C, 450 °C, and 550 °C, respectively. Moreover, the organic bromine in the pyrolysis oil was suppressed by increasing the temperature to 550 °C. The respective contents are 46.02 mg/g, 44.19 mg/g and 38.96 mg/g. The results from this study are useful to provide necessary knowledge for the design and optimisation of the industrial application of PCB pyrolysis devices.