CFD Modeling of Crude Oil Fouling in Pre-heat Train of Crude Distillation Units

Prediction of fouling rate in tube side of crude pre-heaters is investigated based on a 2D Computational Fluid Dynamics (CFD) model developed at Research Institute of Petroleum Industry (RIPI). The crude oil is represented by a model of five pseudo-components, including asphaltenes, salts and sediments, characterized by molecular weight, density and viscosity. The model solves the well know 2D Navier–Stokes equations for incompressible turbulent flow applying the SST version of k −ω model. In order to predict crude oil fouling, mass transfer of asphaltenes, salts and sediments toward the tube wall and the corresponding surface reactions based on an Arrhenius rate scheme have been considered in which they may adhere to the wall or separate from it regarding to the shear stress at the wall. An almost very high apparent viscosity is applied to consider precipitating and adhering of reaction products to the tube wall. To investigate predictability of the developed model, two sets of experimental data were applied for comparison. Results were also compared against those of conventional threshold fouling models and show that the developed model is capable to predict fouling rate in crude oil pre-heaters with less than 20% mean absolute error.