Temperature driving force (TDF) curves for heat exchanger network retrofit – A case study and implications

In the present contribution, concepts supporting a new analysis method to retrofit heat exchanger networks (HENs) are presented. The new graphical representation appears to be simple to use and needs no simulation tools or software packages to perform the retrofit calculations and is found valuable for conceptual applications. The temperature driving force new representation (TDF) is accordingly applied to an existing HEN in an Egyptian refinery to boost its energy efficiency and generate cost-effective opportunities. This refinery is the most recent unit installed in Egypt as it has been built in 1994. Since this refinery is very modern, its energy consumption exceeds the benchmark by only 21.5% which is relatively very low compared to its counterparts worldwide. The graphical revamping in application applied on the HEN shows savings of approximately 10.5% in the energy demand with minor structural modifications, achieving some 60% of the potential energy savings with respect to Pinch Analysis benchmarks. The modified preheat train only exceeds the benchmark by 8.8%. Implications and advantages of the new developed approach are also discussed, highlighting the merits of the proposed method.