Development of PCB Cracking Method by Plasma Heating with Acetylene and without Dioxin Generations

点击翻译按钮获取中文摘要

As a process for cracking PCB with acetylene generation, a new method using hybrid plasma heating followed by gas filter assemblies for cleaning the generated gas has been presented in this research. Equilibrium calculations were conducted for the simulation of both the reaction systems in plasma heating condition and in the heating condition performed by normal electric furnaces, the latter of which is supposing the heating of the filter for burning out the substances caught at the filter. For the equilibrium calculation, a version of GOTO methods has been employed which was developed by this researchers' group. According the results of the simulations, it became obvious that about 90% of PCB can be cracked to be acetylene heated in the temperature range from 1500℃ to 2500℃. The similar conversion ratio is prospected when kerosene is mixed to PCB as a solvent. It has also turned out that the decomposition temperature of dioxin is much dependent on the oxygen ratio in the system at the temperature range given by normal electric furnaces. In order to confirm the formation and decomposition of dioxin experimentally, chlorobenzene was heated with small amount of oxygen in the temperature range lower than 800℃ in a reaction tube of a electric furnace. When the temperature of the furnace was lower than 600℃, few substances reacted were found by the analysis using gas chromatography mass spectrometer. However, a large number of organic substances having benzene ring were found when heated at 700℃ and 800℃. A dibenzofuran, which belongs to the dioxin family and toxic, has been detected when heated with metallic copper as catalyst, though dioxin itself has not been detected yet.