Measuring Method of Solid-Liquid Two-Phase Flow in Slurry Pipeline for Deep-Sea Mining

In order to reduce the influence of fluid noise on the measurement of solid-liquid two-phase flow in slurry pipeline for deep-sea mining, the technique of virtual inductance is introduced to traditional capacitively coupled contactless conductivity detection ((CD)-D-4), a measuring method for solid-liquid two-phase flow based on differential (CD)-D-4 is proposed, and the structure of differential (CD)-D-4 based on three electrodes is designed. The measuring device was verified in conductive fluid channels at different salinity. The results demonstrated that the amplitude of output voltage of the measuring device decreased obviously with the increase of the salinity of the fluid, and linearly associated with the size and volume concentration of the polymetallic nodules. Virtual inductance could reduce the requirement of (CD)-D-4 sensor for the excitation power. The measuring device had less noise of output signal and high accuracy. When the KCl solution containing salinity is at the average salinity of seawater 3.5% and the particle size of polymetallic nodules is from 0 to 25mm, the output voltage increased from 0 to 87mv. The maximum relative error in two-phase flow velocity measurement is 5.2%, which showed that the measuring method for two-phase flow in the slurry pipeline based on the differential (CD)-D-4 is effective.