Design Of Exhaust Gas Treatment Device In Waste PCB Dismantling Process

With the rapid development of the electronic information science and technology and the improvement of the people's living standard,the use of electrical and electronic products is increasing.The use cycle is also becoming shorter and shorter,resulting in a large number of wasted printed circuit boards(PCB).When recycling waste PCBs,the surface elements are usually removed by heating.Waste PCBs will release a lot of toxic,harmful and even carcinogenic exhaust gasses when heated and disassembled.If they are not properly treated,they will cause serious secondary pollution.In order to determine the main chemical components of the exhaust gasses produced during heating and dismantling of waste PCBs,the exhaust gasses were collected and analyzed by means of Fourier Transform Infrared Spectroscopy(FTIR),Gas Chromatography-Mass Spectroscopy(GC-MS),Ion Chromatography(IC),Inductively Coupled Plasma-Mass Spectroscopy(ICP-MS)and X-ray Photoelectron Spectroscopy(XPS).The analysis results show that the main components of the exhaust gasses are organic substances such as phenol,a lot of inorganic acid gasses containing elements such as S,N and Cl,and heavy metals such as Sn,Sb,Pb,Hg,Cr and so on.The pollutants such as heavy metal dusts,inorganic acid gasses and organic gasses in the exhaust gasses were removed by adsorption,absorption and high temperature combustion.A suitable tail gas treatment plan is put forward,and the key equipment of tail gas treatment——spray absorber,has been designed,and the tail gas treatment platform has been built.The CFD software is used to simulate the flow field of the tail gas of the absorption tower.The influence of the inlet velocity v,the inlet angle ? and the entrance eccentricity P on the distribution of the flow field in the absorption tower is studied.The results show that when the inlet velocity of the tail gas inlet of the absorber is v=10 m/s,the inlet angle ?=5°,and the entrance eccentricity P=15 cm,the distribution of the exhaust gas flow field in the tower is more uniform,which is helpful to the full contact of the tail gasses and the purification liquids and the neutralization reactions.Finally,the key structure and parameters of the spray tower are optimized.The design of the inlet horizontal flue,the design of the shape of the entrance,the layout of the spray mother tube,the distribution design of the nozzle and the design of the demister are carried out respectively.