Thermodynamically efficient distillation: NGL fractionation

Natural gas liquids (NGL) are produced in significant quantities from gas wells. Their fractionation to produce ethane, propane, butanes and gasoline is an important gas processing operation. This work tries to improve the NGL fractionation process by designing a more thermodynamically efficient and more economical process. The design is for a one hundred thousand barrels per day (1x105 bbl/day) feed for 8000 hrs per year of operation. Hysys 1.5 was used for all the process synthesis and thermodynamic calculations. Questimate was used to cost the equipment designed and sized using Hysys. Various concepts like distributed distillation, recycle coupling, partial interreboilers, intercondensers, thermomechanically integrated rectification, divided wall (petlyuk) columns and dephlegmators were incorporated in the design, and recommendations have been made based on the economic and thermodynamic impact of these modifications. Economic savings of 42.0 % on utility have been achieved in the recommended design --Abstract, page iii