Performance and Control of Liquid-Liquid Cylindrical Cyclone Separators

The feasibility of using liquid-liquid cylindrical cyclone (LLCC^©) as a free-water knockout device for bulk separation of oil-water mixtures in the field strongly depends on the implementation of control systems due to its compactness, less residence time, and possible inlet flow variations. In this investigation, the LLCC control dynamics have been studied extensively both theoretically and experimentally. A linear model has been developed for the first time for LLCC separators equipped with underflow watercut control, which enables simulation of the system dynamic behavior. A unique “direct” control strategy is developed and implemented, capable of obtaining clear water in the underflow line and maintaining maximum underflow rate. Dedicated control system simulations are conducted using MATLAB/SIMULINK^® software to simulate the real system dynamic behavior. Detailed experimental investigations are conducted to evaluate the system sensitivity and dynamic behavior of the proposed control strategy. The results demonstrate that the proposed control system is capable of controlling the underflow watercut around its set point by obtaining maximum free-water knockout for a wide range of flow conditions, namely, inlet water concentration of 40% to 95% and inlet mixture velocity of 0.2 m/s to 1.5 m/s.