(166b) Performance Evaluation of Alternative Technologies for Fouling Mitigation in Refinery Pre-Heat Trains

While heat exchanger fouling management tools can be effectively used in refineries to minimise the impact of deposition from crude oils, it is desirable to mitigate fouling by design. This has been a challenge for many years in part because of the lack of understanding of the fundamental mechanisms leading to deposition and in part for the intrinsic limitations of the methodologies traditionally used for heat exchanger design. Moreover, opportunities to use non-conventional mitigation technologies (e.g. helical baffles, welded plates, tube inserts) are often missed out, given the challenges in evaluating their performance with respect to traditional shell-and-tube heat exchangers.

In this paper, a methodology to evaluate the performance of different technologies for fouling mitigation with plant data is demonstrated. The hot end of a refinery preheat train is analysed to identify for retrofit opportunities to mitigate fouling. Several retrofit options are proposed for the heat exchanger with greater potential for improvement. By using fouling predictive models, previously fitted and validated using plant measurements, it is possible to re-run history and assess how alternative designs would have performed. The evaluation includes the evolution of fouling, the time-variation of the thermal and hydraulic performance of the heat exchanger retrofitted, the network interactions, and, ultimately, the economic savings that would have been achieved if the alternative technologies had been placed instead of the original one. The methodology is shown to provide a quantitative assessment of the benefits and trade-offs involved in the retrofit, de-risking the selection of non-conventional technology.