Design and Control of a Distillation Column of Separation of Multicomponent Systems

Abstract

Experimental data for the equilibrium of the Nile blend crude was determined. The equilibrium data were correlated (using short cut methods) and an equilibrium model was constructed. This model coupled with a multicomponent material balance was used for the determination of the number of theoretical stages, stage efficiency, and composition and temperature profiles. The work undertaken, lead to a novel design and a mathematical model of the columns that can separate multicomponent systems. Software was developed and might be used for research and development as well as at the stage of starting – up and shut down periods .A case study taking Distillation Column Units( CDU) of Khartoum Refinery was studied and investigated. Three transfer functions around the condenser, the re boiler and the feed plate were determined. A software of MATLAB 7 was used to analys the system stability , these were Nyquist diagram , Bode plot and Routh Hurwtz . Composition profile curves ,T-XY diagram as well as the equilibrium curves were determined using ASPEN PLUS software for multicomponent systems. The transfer function's of the reboiler,condenser,and feed plate were obtained .From the transfer functions created Nyquist diagrams , Bode plots, were converted from Laplace domain to Z domain, using MATLAB7 Software. X-Y profiles were determined using excel software. Also several variables were obtained for the products of multicompent systems using ASPEN PLUS Software. Dimensions of the distillation column design were determined such as number of theoretical stages, number of actual stages, feed stage location and efficiency. A closed loop control strategy for the system was recommended.