Nengiwa, T. O.Manyuchi, M.M2023-06-272023-06-272015-07-23http://localhost:8080/xmlui/handle/123456789/850Refining is a process of refurbishing used oil to high-quality base oil by removing contaminants, water and spent additives. The study involves refining of 1tonne per day used lubricating oil to produce 0.75 tonnes per day refined oil with 80% plant utilization. The process involved dehydration, solvent extraction, hydro-treating and agitated thin film evaporation. Process conditions were experimentally determined. Optimum conditions of 4:1 solvent ratio and 4 mBar evaporation pressure produced refined oil of 24% ash content, 98cP viscosity, -11oC pour point, 180oC flash point and specific gravity 0.909. Detailed major equipment design of an agitated thin film evaporator, its process control and HAZOP was done.enrefining, used oils, lubricating oil, agitated thin film evaporationOther