Research Paper Using Simulation Modelling to Improve the Performance of Chemical Engineering Processes: Part 2 – Retrofitting Heat Exchanger Network

Dagde, Kenneth Kekpugile ; Piagbo, Beabu Kiasira;

Business concerns continue to devise means for minimal energy
utilization due to rising energy cost, environment concerns, and the need to maximise profit. For systems designed during the era of cheap energy, retrofitting becomes a viable option. This research applies heat integration techniques to monitored industrial plant data of a functional refinery to retrofit the preheat section of the Crude Distillation Unit (CDU), using Aspen
Energy Analyser®. The retrofit operations includes modifying utility heat exchangers; resequencing heat exchangers; repiping heat exchangers; addition of new heat exchangers; addition of new area; and eliminating cross pinch heat exchangers. The retrofit design eliminating cross exchangers showed about 14% reduction in total cost, with about 55.37% and 91.22% reduction in the cooling cost and cooling duty respectively. There were also
about 18.97% reduction in the number of shells and 47.1% reduction in the number of exchanger units translating into about 16.57% and 2.74% reduction in operating cost and capital cost respectively, thus highlighting the benefits of retrofitting to a poorly designed network.