Hydrocyclone Separation Efficiency Modeled by Flow Resistances and Droplet Trajectories

The growing demand to optimize the deoiling performance for offshore oil & gas gives the incentive to improve existing control solutions by means of model-based control solutions. This paper proposes a separation efficiency grey-box model of a deoiling hydrocyclone. Grey-box modeling of deoiling hydrocyclones aims to combine knowledge from fluid dynamics with the data-driven parameter estimation to yield better accuracy than black-box derived models while keeping the computational load much lower than CFD-simulations. The model has to be reasonably accurate in all likely operating conditions and be computed in real-time, in order to be beneficial for advanced model-based control. The developed grey-box model is based on flow resistance and oil droplet trajectory analysis. The model functionally describes how the valve openings, inflow rates, and PDR set-points affect separation efficiency of the considered generic deoiling hydrocyclone. The results are reasonable and provide a fundamental overview of how the operational conditions affect separation efficiency. The model can be extended to account for changes in the axial velocity distribution, coalescence and breakup of droplets.