Sensor Of Conductance Probe For Liquid Film Measurement In Horizontal Annular Flow

Gas-liquid two-phase annular flow is widely existed in industrial field such as chemical engineering,petroleum,nuclear reactors and so on.The characteristic parameters and evolution of liquid film are great important for the safety and efficiency of the industrial process.Therefore,the accurate measurement of liquid film thickness is fundamental for investigating these characteristics.In this paper,two type of sensors based on the conductance theory have been designed for different measurement requirements.It is realized to measure the liquid film thickness and wave velocity of gas-liquid two-phase annular flow in horizontal tube.The main content is as follows:1.The structure of the conductance probe with adjustable insertion depth is designed.A calculation method of liquid film thickness using duty ratio weight is proposed.So it is realized to directly measure the liquid film thickness online.Its theoretical error was analyzed and two key parameters,the insertion depth increment and statistics time of duty ratio,are selected.The measurement error is less than 2% when insertion depth increment is 10?m and the statistics time of duty ratio is 5s.Experiment is done on moisture setup in Tianjin University which shows that this new method for measuring liquid film average thickness online is feasible.Compared to in direct method,it has the advantages as follows: no calibration,no affect with the change of conductivity.2.The structure of the conductance probe array is designed.As for the signal coupling issue between conductance probes,it is acknowledged that the circumferential probes must work in different time and the axial probes can work together after simulation analysis.Combined with cross-correlation velocity measurement,it is realized that the distribution of circumferential liquid film thickness and circumferential wave velocity is measured respectively.Experiment result shows that the liquid film thickness decreases with the increase of angel and the wave velocity remains the same with the increase of angel.3.Using the data of bottom liquid film thickness from the conductance probe array,more analysis has been done to observe the evolution of the interfacial wave from ripple to disturbance.Combined with cross-correlation velocity measurement,it is realized that the wave velocity of bottom liquid film thickness at different height is figured out.Experiment result shows that the wave velocity of top area is fast and the wave velocity of bottom area is slow.