Modeling and operability analysis of water separation from crude oil in an industrial gravitational coalescer

• An industrial gravitational coalescer is modeled based population balance method.
• Accuracy of the developed model is proved against plant data.
• Effect of input variables is studied on water and salt removal efficiencies.

The main aim of present study is to develop a mathematical model to analyze the performance of an industrial gravitational coalescer to separate water from crude oil. The considered process consists of a mixing valve and coalescer tank that connected in series. Gravitational coalescer is a huge two-phase separator that separates free water from crude oil based settling time. In this research, the water removal from crude oil is simulated based on a two-dimensional model at steady state condition. The population balance method is used to predict drop size distribution in mixing and coalescence stages considering breakage and coalescence terms. To prove accuracy of the considered model and considered assumptions, the outlet water cut, water removal efficiency and salt content from gravitational coalescer are compared to plant data. Then, effect of temperature, fresh water rate, and mixing pressure drop is studied on water and salt removal efficiencies. The simulation results show that there is an optimum condition to maximize water and salt removal efficiency in desalting process.

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