Revamping of crude distillation unit for enhancement of processing capacity and LPG extraction through steady state simulation modeling

Abstract

The scope of this work covers the debottlenecking of operational constraints for increasing the processing capacity of crude distillation unit and LPG extraction from crude oil. Simulation modeling on Aspen HYSY V7.1 is used for thoroughly investigating and evaluation of retrofit alternatives. Design and operations data of a crude distillation unit at Attock Refinery Limited is used as a case study. Capacity expansion through the addition or rearranging of circulating reflux/Pump-around is selected among the various available revamp alternates like addition of Pre-flash columns, tray geometry and hydraulics etc. Then crude distillation unit is revamped for maximum possible expansion in processing capacity by re-arranging of Pump-around circuits. Pump-around balances re-arranged based on specific crude oil operating blend. Some modifications are also proposed in stabilizer section of the crude distillation unit to enhance LPG extraction from crude oil and finally crude distillation unit  simulated for revamped processing capacity with re-arranged pump-around circuits and suggested modifications in stabilizer section. The results of Simulation Modeling validate propose modifications for revamping of processing capacity and LPG extraction.