Dispersed Oil–Water Two-Phase Flow Measurement Based on Pulse-Wave Ultrasonic Doppler Coupled With Electrical Sensors

Abstract

Oil–water two-phase flow commonly exists in many industries. The accurate measurement of flow velocity is beneficial for safety operation and economic efficiency. A combination of a pulse-wave ultrasonic Doppler (PWUD) sensor and a conductance/capacitance (CCC) sensor is proposed for flow velocity measurement in dispersed oil–water two-phase flow. The PWUD sensor estimates dispersed phase velocity, and the CCC sensor provides phase fraction. The overall superficial flow velocity ( $J$ ) and individual flow velocities are estimated by combining the outputs of the two sensors. The dual-modality sensing system was designed and experimentally verified on a horizontal multiphase flow loop. Ignoring the slippage between two phases, the $J$ is estimated with an average relative error (ARE) of 5.58%, water superficial velocity with 6.42%, and oil superficial velocity with 6.91%. To further improve the measurement accuracy, slip velocity-based measurement model is presented by introducing the drift-flux model. The distribution parameter of this model is derived from theoretical analysis. The correlation between relative velocity and $J$ is analyzed by the force analysis of dispersed phase in water/oil-continuous flow theoretically and experimentally. The results demonstrate that the proposed model estimates the $J$ with an ARE of 2.21%, water superficial velocity with 3.56%, and oil superficial velocity with 3.80%. Besides, ARE of different flow patterns shows a uniform distribution. The slip velocity-based measurement model has an advantage of less error in overall superficial flow velocity estimation, reduced by 60% compared with that of the nonslip velocity-based measurement model.