STUDY OF HEAT EXCHANGER NETWORK CLEANING SCHEDULE DESIGN WITH HEURISTIC SCENARIO ANALYSIS

The crude oil refinery heat exchanger network (HEN) cleaning schedule is critical to maximize the energy recovery and simultaneously maintain the HEN performance. In reality, the HEN configuration consists of multiple heat exchanger units with different sizes, fouling rates, and initial efficiencies. The plant availability and the HEN efficiency may decrease to a certain level after a period of operation due to fouling and heat exchangers taken offline for cleaning. Therefore, cleaning and bypass procedure is deemed necessary. In this study, the heat exchanger performance represented by the overall heat transfer coefficient is evaluated based on a proposed heuristics algorithm for seeking the optimum cleaning schedule while incorporating rigorous cleaning rules. Four heuristic values for HEN cleaning schedule scenarios are proposed to evaluate the overall performance of the HEN. The additional heat duty on the process heater due to cleaning operation and the total annual cost are considered in a crude oil refinery HEN that consists of 11 heat exchanger units. The cleaning frequency of the heat exchanger is found to have a significant effect on HEN performance. The results from the scenario analysis suggest that there is a proper cleaning schedule for optimum operation of a crude oil refinery HEN. It is also indicated that the design of the cleaning schedule depends on fouling resistance and the capacity of related heat exchangers.