Investigating the Effecting Phenomena on the Asphaltene Particle Deposition in Crude Oil Preheaters Using the Eulerian-Lagrangian approach

One of the serious problems in the oil and petrochemical industry is the deposition of crude oil in the preheaters of the distillation unit. Deposition increases the thermal resistance and increases the pressure drop in preheaters, which leads to increase of energy consumption and decrease of overall system efficiency. The main source of deposit in preheaters is a substance called asphaltene, which does not have a definite molecular composition. Generally, deposition involves two stages; one is the transport of insoluble particles to the surface and the other is to stick particles to the surface. So far, a major problem in the simulations is the lack of attention to phenomena that can play an important role near the surface and failure in modeling of particle stacking correctly. In this study, focusing on the boundary layer flow, phenomena that affect the particle deposition process near the surface were investigated. In this regard, the path of motion of particles is followed by Euler-Lagrangian approach, and the bonding stage is modeled using the concept of deposition critical velocity. Numerical solver is validated using available experimental data for aerosol and also with the scanning electron microscopy data. Obtained results show that the dominant force that affects the particle motion in the boundary layer is Brownian force. The deposition velocity is calculated for different diameters and it is shown that with the decrease in the diameter of the particles, the deposition velocity increases.