Search

In this study, the deposition rate of asphaltene particles is modeled considering the asphaltene particles interactions using the population balance approach. The modeling consists of three sub-models: (1) The distribution of the asphaltene particles along the pipe, (2) The transfer of asphaltene particles from the bulk to the wall using the Eulerian approach, (3) Adhesion of asphaltene particles to the wall. The most important transport and deposition mechanisms, including the drag, molecular diffusion, eddy diffusion, turbo-phoresis, and thermo-phoresis, are considered in simulations. To calculate the adhesion velocity, the concept of the adhesion coefficient is employed for particle bins. The results of adhesion velocity show that the particle size, surface temperature and fluid velocity strongly affect the adhesion of particles. Therefore, accurate modeling of the adhesion step considering the interaction of the particles has significant effects on the prediction of asphaltene deposition rate. Furthermore, the effects of changing the process conditions including the surface temperature, fluid velocity and asphaltene concentration on the deposition rate and size distribution of particles, are investigated. The results showed that considering the particle size distribution and particles’ interaction reduces the error of numerical simulations. The developed framework can be employed for further investigation of asphaltene deposition using multi-fluid approaches.

In this study, the asphaltene deposition and the fouling layer growth are modeled using the multi-fluid approach. The crude oil is considered as a multi-species fluid which the asphaltene species can deposit on the heat transfer surfaces due to the volume reaction. The effective mechanisms of asphaltene particle transport are the molecular and eddy diffusions. Therefore the species modeling approach is utilized for particles transport by diffusion processes in the carrier phase. To model the fouling layer growth without considering an initial thickness for the deposited layer, extra terms are added to the momentum equations of primary and secondary phases. The results of the numerical model are validated against available experimental data and a good agreement is seen. Finally, the developed model is applied for a specific case and the effect of fouling layer growth on the fluid velocity, the temperature variations, and the heat transfer rate are investigated. The results show that the heat transfer rate decreases during the fouling and the developed model could predict accurately the physics of fouling layer growth.