Measurement of Liquid Film Thickness Using Distributed Conductance Sensor in Multiphase Slug Flow

In this article, a novel coaxial three-electrode distributed conductance sensor (CTDCS) is proposed to achieve the salinity and oil content independent measurement of the liquid film thickness in multiphase slug flow. The conductance sensor obtains the liquid film thickness by measuring the conductance between the electrodes. However, the conductance depends on the liquid film thickness and liquid conductivity. For gas-water and oil-gas-water flows in an industrial process, the variations of the salinity and oil content of liquid phase change the liquid conductivity. This will seriously affect the measurement of the liquid film thickness using a conventional two-electrode sensor. Owing to its novel three-electrode configuration, the proposed CTDCS can overcome the problem mentioned above. The optimal geometry of the CTDCS is determined by exhaustive search using a finite-element method, and the electronic circuit suitable for the condition of conductivity variation is investigated. The ratio of two-channel outputs, which is independent of conductivity is acquired and its relationship with the liquid film thickness is established. The advantages of the CTDCS are that it can online compensate conductivity variations and acquire the circumferential distribution of liquid film thicknesses. Hence, the salinity and oil content independent measurement of liquid film thickness is realized for the first time.