Retrofitting Options for Natural Gas Liquid (NGL) Fractionation Trains Using the Concept of Single Column Development

Abstract Heat pump assisted distillation (HPAD) system and self-heat recuperation technology (SHRT) have been developed as a result of intensive research to reduce energy consumption of a conventional distillation system. To determine a suitable system for natural gas liquid (NGL) fractionation trains, rigorous analysis and comparative study of several HPAD and SHRT options for the retrofitting of a single column were studied in the present work. The retrofit options considered were vapor compression (VC), mechanical vapor recompression (MVR), thermal vapor recompression (TVR), bottom flashing (BF), side heat exchanger (SHE), intermediate heating and cooling (IHC), self-heat recuperative (SHR) and modified self-heat recuperative (MSHR) distillation. A depropanizer column commonly used in typical NGL plant was selected as a case study. Aspen HYSYS V7.3 was initially used to simulate the eight selected retrofit designs under common sets of criteria. The data from the simulation was then analyzed to determine the best design in term of energy cost reduction. The analysis shows that the MVR gives the highest energy cost reduction of 68.11% as compared to that of the base case (BC) conventional column. It is followed by VC (66.65%), MSHR (64.02%), BF (62.88%), SHR (55.85%), SHE (54.23%), IHC (39.54%), and TVR (12.41%).

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