Research On The Flowrate Measurement Of Low Conductivity Fluid

Low conductivity fluid is usually the fluid whose conductivity is lower than10uS/cm, including oil, petroleum production, gas and most of the organiccompounds. How to measure the flowrate of low conductivity fluid has greatmeanings in industrial manufacture. The existing measurement methods based onelectromagnetic theory could only decrease the lower limit of the conductivity in acertain extent. Those methods doesn't solve the problem radically. The author of thisdissertation proposed a new measurement method: by changing the fluid'sconductivity character temporarily, to measure the flowrate of low conductivity fluid.The main contents of the dissertation could be summarized as follows:(1) A brief introduction was stated to describe the current situation anddevelopment trend of fluid measurement technology, the conception of lowconductivity fluid and the difficulties in its flowrate measurement. Byresearching the actuality of low conductivity fluid measurement technology,a new measurement method based on electric charge injection device wasproposed.(2) Designing and establishing the experimental platform. The air was chosenas the research object. The relationships between the flowrate ofelectrification air and inductive potential of electrode were confirmed byanalyzing the experimental data and the main factors which influence theinductive potential were discussed.(3) A new flowrate measurement method based on electric charge injectiondevice was proposed in the dissertation. The influences to the measuringresult that were caused by the changes of environmental conditions wereeliminated based on using correlation analysis, thus the method couldmeasure the high flowrate accurately.(4) The influence to the electrode potential, which was caused by high negativevoltage field and the electromagnetic disturbance, was weakened through the hardware anti-jamming design. The disturbance to the transit time,which was caused by intensive differential interference, was eliminatedbasically by using digital filter technology; therefore the method couldmeasure the low flowrate accurately.The innovation in this dissertation is list below: A new measurement methodbased on electric charge injection device was proposed. The research on flowratemeasurement was done by changing the conductivity of fluid temporarily. Usingcorrelation analysis eliminates the influences to the measuring result, which was causedby the changes of environmental conditions. Designing the anti-jamming hardwareand using digital filter technology weaken the disturbance towards the inductivepotential and transit time. Therefore the lower limit of flowrate measurement wasdecreased.