Study On The Measurement Of Oil-Water Two-Phase Flow Using Conductance Probe With Vertical Multi-Electrode Array

Abstract:Aimed at the measurement problems of oil/water two phase flow, a newconductance probe with Vertical Multi-Electrode Array (VMEA) is presented in thispaper. The VMEA consists of eight metal ring electrodes which are separately flushmounted inside the pipe and include a pair of exciting electrode and phase volumefraction measuring electrode and as well two pairs of velocity measuring electrode.Based on this kind of structure, the VMEA can be used to measure phase volumefraction and mixture velocity simultaneously. However, the previous structuralparameters of ring electrode sensor are proposed on the basis of experience andsimple qualitative investigation. In order to improve the measuring accuracy, it isnecessary to propose a new scheme for the optimization of the VMEA. Using FiniteElement Method (FEM), distribution of electric field distributed inside the VMEA iscalculated. At the same time axial uniform degree and radial uniform degree aredefined to investigate the uniformity of the electric field. By introducing the conceptof sensitivity, distribution of sensitivity of phase volume fraction and mixturevelocity measuring electrodes are calculated in a wide range of electrode spacing.Synchronously, 'equality' of the information obtained from fluids field are guaranteed.For the purpose of getting as much information as possible, the concepts of totalinformation volume, effective information volume and concentration of effectiveinformation are defined and applied to investigate the 'extractive capability' of theVMEA. Finally, by using new-defined integrative evaluating indicators, theoptimized structural parameter of VMEA is obtained. By employing the optimized VMEA, the measuring models of phase volumefraction and kinematic wave theory are applied to make a further study of theextracted data on the VMEA; thereby the practical meaning of cross-correlationvelocity is expounded to a further extent. The method proposed for the optimization of the VMEA can be extensively usedfor the optimization and design of similar conductive type of sensor, such as plateelectrode, arc electrode and so on, which can be used for the measurement of twophase flow. Due to the distinct difference of the conductance of oil and water, themulti-electrode array sensor and measuring model can as well be used to performinvestigation of the two phase flow with insulating discrete phase distributed in theconductive continuous phase, such as gas/liquid, solid/liquid and so on.