Two Phase Flow Measurement Method Of Intrusive Array Conductance Probe

Two phase flow phenomenon widely exists in industrial producing process and the measurement of the flow parameters is of great significance for industrial producing process and the optimization of process. The existence of randomly changing interface of two phase flow makes the flow structure complex and the flow pattern changeable, in which the parameters are difficult to measure. Simultaneously, the two phase flow phenomenon behaves as non-stable and multiscale nonlinear auto organization characteristic. Therefore it's an effective approach to solve the measurement of complex two phase flow parameters by the fusion of advanced array sensors and modern information processing method and theory. In the paper which mainly aims at the two phase flow measurement problem in oil well of petroleum industry, a intrusive array conductance sensor is designed which is capable of measuring the phase fraction and flowrate simultaneously. Based on the dynamic signal measured by multiphase flow facility, the nonlinear dynamic characteristics of two phase flow patterns were studied by using multiscale nonlinear analyzing method. The flowrate of two phase flow was measured by soft measurement method based on characteristics extracting and information fusion. And the innovative research fruits are shown as below:1. The electrical field distribution characteristics of intrusive array conductance probe were analyzed using finite element method, and the geometry size of intrusive array conductance probe were optimized. Then the power module which could realize over voltage protection and over current protection, exciting module which could be set to constant voltage or constant current exciting mode and the signal modulation module were designed. And then a portable data acquisition system based on embedded real time operating system was developed, which could complete high speed parallel acquisition, had embedded file system and could save the sampled data in removable storage devices through USB peripheral communication port, which also could realize communication between machine and human by serial port, keyboard and LCD screen.2. The multiscale nonlinear dynamic characteristics analysis method of two phase flow patterns was brought forward. And then based on this, the fluctuant conductance signals of 132 two phase flow conditions were analyzed, which collected by using array conductance sensors in upward vertical gas-liquid two phase flow. The results indicated the changing rate of sample entropy at small scales could classify the three typical flow patterns (bubble flow, slug flow and churn flow), and the fluctuation of sample entropy of large scales reflected the dynamic characteristics of each flow pattern. The stochastic characteristic of bubble flow was shown as higher and oscillating sample entropy at large scales; the intermittence of gas slug and liquid slug of slug flow was represented as lower and stable sample entropy of large scales; the unstable and oscillating characteristics of churn flow behaved as the entropy between that of bubble flow and slug flow, and the entropy closed to that of bubble at larger scales. The multiscale entropy analysis of two phase flow is helpful for understanding the dynamic characteristics of flow pattern transition, and the rate of multiscale entropy is a new indicator of flow pattern identification.3. Aiming at soft measurement problem of two phase flowrate researched with intrusive array conductance probe, the support vector machine soft measurement model based on particle swarm algorithm and quantum particle swarm algorithm were developed. After the proof-testing with six single peak or multi peak functions, the algorithm was proved to have higher searching efficiency and higher accuracy of seeking optimum. Based on this, the temporal and frequency characteristics of the phase fraction fluctuant signal acquired by phase fraction electrode of intrusive array conductance probe were extracted, and then prediction model of phase fraction and phase flowrate based on support vector machine with the quantum particle swarm algorithm was established. The prediction results indicate that the average percent deviation of water flowrate fraction is 2.06% and that of individual phase flowrate is about 10% at the water phase flowrate range of 0.2m3/h～12 m3/h, the air flowrate range of 7m3/h～60 m3/h and the water flowrate fraction range of 0 ~ 0.6.4. For the flowrate measurement issue of gas-liquid two phase flow in gas production well, the combined measurement method of petal type concentration turbine flowmeter and array conductance sensor was proposed. The combination of moment parameter based on attractor morphological characteristics and the combination of rate of entropy of low-scale and high-scale calculated by transient fluctuating signals acquired by conductance sensor could effectively identify the unseen gas-liquid two phase flow patterns in concentration channel. The turbine flowmeter could measure the total flowrate of gas-liquid two phase flow with high-precision for the flow condition with petal type concentrating diverter. After the temporal and frequency characteristics of the phase fraction fluctuant signal of concentration channel were extracted, combined with the flowrate information gotten by turbine flowmeter, the high precision phase flowmeter of gas liquid two phase flow was predicted by soft measurement method based on information fusion, and the measurement method was indicated as a new way to solve the gas liquid two phase flow of median and low yield gas production well.