Application Research Of Capacitance Sensor In Gas/Liquid Two-phase Flow Parameter Measurement

Gas-liquid two-phase flow is very common in nuclear reactors and other fields,especially in the boiler industry,circular flow is the most common flow pattern.In the petroleum industry,the oil gas flow in the wellbore and the platform riser is often in a circular flow.Void fraction is widely present in people's daily life and petrochemical production.The measurement of void fraction is not only of great significance to the personal safety of the construction personnel,but also related to optimizing the production process and technology,and simplifying other parameter measurement and measurement methods.There are many methods for measuring void fraction,and capacitive sensors are one of them.In use,capacitive sensors are not only easy to manufacture,safe and economical,but also high-precision measurements can be achieved without intrusive measurement.In this paper,design a system that measures the gas-liquid two-phase annular flow void fraction in real time using a ring-type capacitance sensor consisting of a capacitance sensor power supply,a signal excitation module signal processing circuit and a host computer display module.Through the analysis of the experimental value of the void fraction,conclusions are drawn and optimization suggestions are made for the shortcomings in the experimental process.The main contribution of this paper is to solve the Laplace equation that the electric potential distribution satisfies,and obtain the calculation formula of the void fraction and the voltage variation with correction coefficient.Then use finite element simulation and experiment to optimize the electrode structure,and determine the optimal width and spacing of the ring electrode suitable for this experiment.Use NI my DAQ for data acquisition,based on the Lab VIEW software programming language through the use of G,design PC display program,realize the real-time display of the void fraction When the width of the annular electrode of 35 mm,two electrode spacing is 70 mm,on the basis of the electrode structure,build a void fraction measurement system.Through experiments,it is found that the system can meet the void fraction measurement of a certain range,which proves that the experimental device can realize the void fraction measurement in the gas-liquid two-phase annular flow.