Research Of Pyrolysis Technology And Equipment For Recycling Waste Cables And Motors

This paper aims to develop a green technology and equipment for recycling scrapcables and motors, funded by Tianjin Science and Technology Innovation fund.Because of the existing of PVC molecules in scrap cables, traditional incinerationmethods pollution will exhaust lots of pollutant gas, so the cost of the exhaust gastreatment processing is very high. Pyrolysis technology as a new thermochemicalmethod, has advantages in reducing the harmful substances in exhaust emissions, andthe effective recovery of raw materials and the metal component, which is consideredas a potential alternative of incineration. Therefore, appling organic molecularpyrolysis principle, we developed a suitable cleaning technology for recycling usefulmaterials and metals in waste machinery and electronic products. The specificresearch contents:(1) TGA analysis of scrap cable insulationsApplication of thermogravimetric analysis (TGA), we analyzed the characteristicsof the two main insulation materials—PVC and PE; measured the characteristictemperature; calculated the kinetic parameters, and established the dynamics model ofthe pyrolysis reaction of the two materials. Results show that, the activation energy ofPVC and PE insulation materials were152kJ/mol and160kJ/mol. This part is thebasis experimental study.(2) Design of a new type semi-pilot scale device for recycling scrap cables andmotorsConsidered of the basis parameters of insulation materials, combined with thecharacteristics of scrap cables and motors, we designed and manufactured a new typesemi-device for recycling scrap cables and motors, which has advantages ofconvenient loading, efficient heat transfer and good insulation performance, low costand low cost of flue gas treatment.The main innovation of this process is that the sythesis gas produced by pyrolysisof insulations combusted under high temperature, with no condensation process. Webelieve that condensation process of high temperature sythesis gas will not onlyincrease the complexity of the device, and cause a lot of heat loss. From previousexperience, we see that the obtained tar must pass through a deeper processing tobecome a supplemental fuel. Therefore, the device is designed with a high temperature sythesis gas combustion system. The calorific value of sythesis gas canreach50.94MJ/m3.(3) Semi-pilot scale experimentThe vatiation discipline of the composition and calorific value of sythesis gaswith pyrolysis temperature was tested. Product distribution characteristics weremeasured, and the composition and calorific value of residue char were tested. Resultsindicate that, pyrolysis process of scrap cables is divided into two stages, the firststage for the emergence of HCl, the second stage for producing a combustible sythesisgas. The calorific value of combustible sythesis gas is50.94MJ/Nm3. The content offixed carbon in residue char is23%, and the calorific value of the char is1776kJ/kg.Application of static economic analysis and dynamic economic analysis index,pyrolysis scheme for scrap cables and motors is evaluated. The program’s internalincome rate reached40%, which indicates a great potential of further industrialization.