Mzirai, B. K.2019-04-232020-01-072019-04-232020-01-071982Mzirai, B. K. (1982) Preliminary plant design and economics for re-fining used lubricating oil, Masters dissertation, University of Dar es Salaam. Available at (http://41.86.178.3/internetserver3.1.2/detail.aspx)http://localhost:8080/xmlui/handle/123456789/1261A plant for re-refining 15,000 cubic meters per annum of used lubricating oil in Tanzania is being studied. The amount is based on the recoverable amount of used lubrication oil when serious measures on collection will be undertaken in Tanzania. Two designs are being considered in this project. One design for a cheaper plant i.e. where sulfuric acid and clay are employed with a modification of heating the mixture under vacuum to remove water and light ends, and then filtering. The second design, a more expensive one employing treatment of used oil with a surfactant then filtering, with the modification of vacuum distillation in order to be able to get different fractions of different viscosities. The following equipment’s are considered in the former design, tanks and vessels, retort, heat exchanger, pumps pre-filter, and filter press. For the latter design, tanks and vessels, reactor, filter press, compressor and a vacuum distillation unit. The design of the equipment has been based upon the material balances, enthalpy balances, in different process streams, viscosity, and pressures in different vessels. Where possible and economical, heated economy was also considered. The process design also covers the estimation of cost of collection of used lubricating oils, equipment cost estimation, fixed capital, investment cost estimation, and the estimation of the total production cost. The graphical determination of the breakeven point is carried out. The rate of return on investment is also obtained and the discounted cash flow rate of return is also determined graphically. The payout period of the project is determined from the accumulated net cash inflow.enLubricating oilsFactories designLubrication and lubricantsValuationGrainmillingTechnology assessmentThesis