(22j) A CFD Model for the Washing Zone in Coker Fractionators

The washing zone region in coker fractionators plays a fundamental role avoiding the undesirable coke formation. This project aims to develop an accurate CFD model for the washing zone, including the vapor (feed) and the washing liquid, taking into account the heat and mass transfer between phases. The main goal when developing this model is to be able to predict the necessary height for the vapor to reach the required temperature and to avoid the coke formation in this region. The model allows the evaluation of not applying internal baffles, which are normally used to increase the interfacial area and improve vapor distribution. The use of an empty spray section could improve the efficiency of this region reducing the required height, and increasing the fractionation space. To predict the liquid phase behavior, a Lagrangian approach was used together with a non-ideal Soave-Redlich-Kwong equation of state to model the phase equilibrium and fluid properties calculation within the condensation and evaporation models. The hydrocarbon mixture was represented using five pseudo-components. Mass transfer was modeled to represent mass exchange between liquid and vapor for all the components involved. The model was capable to reproduce the complex phenomena of interfacial heat and mass transfer on multi-component multiphase flow, providing interesting input to help engineering decisions.