A New Microwave Assisted Recycling Process For Cascade Utilization Of Waste Engine Oil

Almost 24 million tons of waste lubricating oil can be produced in the world every year,which poses an important environmental challenge for modern society.Waste engine oil is a mixture of aliphatic hydrocarbon and aromatic hydrocarbon,which has potential value in producing high calorific value fuel and chemical feedstock.Nowadays,most countries still incinerate and combust waste engine oil directly to obtain energy.Furthermore,there are also vacuum distillation,hydro-treatment,pyrolysis and other waste engine oil treatment methods.However,these treatment methods only focus on obtaining chemical feedstock or energy from waste engine oil,while waste engine oil has not been completely treated,resulting in secondary pollution to the environment.Therefore,the development of clean and efficient waste engine oil recycling technology has attracted more and more attention of researchers.The purpose of this paper was to demonstrate the feasibility of integrated recycling process of vacuum distillation(VD)and microwave pyrolysis(MP)to cascade utilization of waste engine oil(WEO)for production of lubricant base oil and fuel.The vacuum distillation experiment of waste engine oil was carried out.Before and after VD process,the physical properties of WEO and REO were tested.The results revealed that the integrated process produces high quality re-refined engine oil and pyrolysis products with scarcely any char remained,which could avoid the secondary pollution as much as possible.It showed that the VD process effectively removed contaminants from WEO,returning REO to a quality essentially equivalent to fresh oil and could be reused as lubricant base oil after finishing process.After that,microwave pyrolysis was performed on the residual engine oil in the kettle.In addition,the experiments were also carried out to study the influence of operating conditions during the MP process(absorbents spatial distribution,final temperature,microwave power and nitrogen flow rate)on the yield and compositions of the pyrolysis products.The results showed that the selection of appropriate microwave pyrolysis process parameters was beneficial to improve the yield of pyrolysis products and target chemicals in the products.The calorific value of oil samples was analyzed and the energy recovery efficiency of polygeneration process was studied,which compared with the single microwave pyrolysis process at the same time.The aspects of environmental and energy efficiency of this integrated process were evaluated.Considering the energy consumption of process,the integrated process was more energy-efficient than the single process of microwave pyrolysis.The experimental results demonstrated that the advantages of this integrated technique included substantial reduction in consumption of cost and pollution during the recycling of WEO.Almost the whole WEO was converted into valuable products after integrated recycling process,enhancing the product value as well as avoiding the secondary pollution.The results indicated that the integrated process showed exceptional promise as a novel means for recycling and treating WEO.