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CFD Simulation of Brine Droplets in Crude Oil under the Influence of Electric Field in Oil Desalter

Ghaffari, Ali | 2011

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 42379 (06)
  4. University: Sharif University of Technology
  5. Department: Chemical and Petroleum Engineering
  6. Advisor(s): Farhadi, Fathollah
  7. Abstract:
  8. Brine in crude oil causes many problems that underpin the importance of its separation. In recent years brine in crude oil has been increased with increase of the oil fields lifetime and its separation has been more important. One of the most effective separation methods is electrocoalescence. In this research, the simulation of brine droplets motion and their coalescence under the effect of electric field have been investigated by using the Computational Fluid Dynamics method and the droplets size distribution has been calculated under different values of electric field magnitude. The motion of two single brine droplets in stagnant oil phase and the behavior of many numbers of droplets in turbulent flow have been investigated and simulated under the effect of electric field. Coding was used for simulation of two droplets motion and the FLUENT software was used for simulation of many droplets in turbulent flow. Furthermore beside the use of this software, user defined function (UDF) was used to calculate the inter droplets electric forces and film thinning force. In order to calculate interdroplet electric forces, some equations were derived according to the analytical models by using the least square error method. These equations are usefull in the view of accuracy and simplicity for the systems including many numbers of droplets. The simulation for Horizontal and Vertical electrodes was done and the effect of different parameters on electrocoalescence was investigated. The effect of parameters such as electric field magnitude, droplet sizes, volume fraction of dispersed phase, inlet velocity, operation temperature, interphase tension and continuous phase viscosity were investigated. In order to compare the effect of different parameters an efficiency was defined as the percent of droplets with diameters larger than the twice of inlet droplets average diameter. Also the collision time for two droplets under the influence of different values of electric field magnitiude and initial distance of droplets was calculated. Calculated collision time is useful for design of electrodes. The results obtained by simulation agree with experimental observations in the literature
  9. Keywords:
  10. Electro Static Force ; Computational Fluid Dynamics (CFD) ; Desalter ; Electro Coalesence

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