(166b) Design Approach for Mitigating Fouling of Reboilers and F/e Exchangers

Significant progress has been made in understanding the underlying mechanisms of hydrocarbon fouling and characterizing the effects of physical and chemical parameters. However, the research and development focuses on single-phase flows. Industrial heat exchangers in refining and petrochemical plants operate under multi-phase flow conditions and fouling and localized corrosion is a common problem in such heat exchangers, particularly in reboilers. This is because design guidelines are inadequate to minimize localized process conditions that induce severe fouling, which could also lead to localized corrosion. In a new design approach conditions under different operating conditions of reboilers and feed/effluent exchangers are evaluated and the propensity of high fouling rates are detected on the basis of fluid and thermal condiitons that may trigger chemical mechnisms of precursor formaiton. The design approach in this study is based on evaluating local threshold condiitons and designing reboilers and F/E exchanger to minimize propensity of precursor generation. Such a design may not be optimum from heat transfer and pressure drop for clean conditions, but it will minimize fouling and localized corrosion. The result is lower lifecycle ownership cost of the exchanger.