Experimental Study On The Heat Transfer Characteristics In Process Of Waste Printed Circuit Boards Pyrolyzed

With the increased demand of electronic products and the acceleration of electronic product updates,as the most basic and essential component of electronic products,the number of waste printed circuit boards(PCB)is increasing.Therefore,waste PCB are becoming more and more urgent to be reduction,recycle and safe treatment.Pyrolysis technology which has the advantages of high recovery rate of metal and nonmetal,high recovery purity and low risk of secondary pollution has become a main way to recover and process waste PCBs.In order to study the heat transfer characteristics in the pyrolysis process of waste PCB,a pyrolysis experiment device has been designed and established.The temperature and pressure distribution of the material layer as well as the size and migration rates of the thermal infiltration area of waste PCB and talc porcelain particles were investigated experimentally in pyrolysis process and the interaction between thermal chemical reaction and physical heat transfer during pyrolysis process was analyzed.In addition,the components of the solid,liquid and gaseous products were analyzed.The experimental results indicated that when the heating temperatures were 600? and 700?,the average migration rates of pyrolysis reaction zone along the vertical direction were 0.68cm/min and 1.00cm/min,respectively.However,the average migration rates of talc porcelain were 0.54cm/min and 0.68cm/min,respectively.The temperature difference between center and the half of radius was small in the same height in furnace,and material particles in the middle of the same horizontal plane were in the same pyrolysis state.Thanks to the heat dissipation of the furnace wall,the pyrolysis region showed the phenomenon of first appearing in the middle,and then appearing around in material layer.When the pyrolysis process was completed.the pyrolysis solid residue accounted for 76.15% and 76.90%,the pyrolysis oil accounted for 16.98% and 15.02%,non-condensable gas accounted for 6.87% and 8.08% under heating temperature of 600? and 700?.Besides,the main components of pyrolysis oil were differences under different heating temperature.Different heating temperatures can be determined according to the different needs of the pyrolysis products.