Energy Recovery in a Naphtha Splitter Process through Debottlenecking of Retrofitted Thermally Coupled and Double-Effect Distillation Sequences

Abstract

A thermally coupled distillation sequence (TCDS) and a double-effect sequence (DES) were proposed to retrofit an existing naphtha splitter process in the refinery plant for enhanced energy efficiency. This, however, can create a bottleneck in the columns. A side reboiler was proposed to debottleneck the retrofitted columns. The concept of minimum vapor flow rate was used as a preliminary calculation to determine the benefits of these proposed arrangements. A practical optimization using the response surface methodology was applied to the design of TCDS and DES. In addition, a column grand composite curve was used to highlight the thermodynamic feasibility of the implementation of a side reboiler into the retrofitted sequences. As a result, the DES was shown as the best alternative through combination of a side reboiler, and this achieved 32.7 % savings on operating costs with a maximum reuse of the existing equipment.