Study On The Measurement Method Of Gas Holdup Of Gas-liquid Two-phase Flow Based On Ring-shaped Conductance

The track of horizontal well exists a certain amount of ups and downs,which caused the flow of gas-liquid two-phase and the blockage of coal powder in the process of coal-bed methane.By studying the flow mechanism of gas water two phase flow in the undulating well-bore,the law of settlement,floating and migration of pulverized coal under different flow mechanism is obtained.Based on the annular conductance sensor,a system is designed to monitor the flow pattern of gas and liquid two phase flow in the well-bore and to detect the gas holdup in the well-bore.The ring-shaped conductance sensor is widely used in multi-phase flow parameter measurement.The advantage is that the measuring range can cover all the areas within the circumference of the pipe.In this paper,a method for measuring the gas holdup of gas-liquid two phase flow is designed based on the ring conductance sensor.By analyzing the influence of flow patterns on its structure,the structural parameters of the ring-shaped conductance are optimized and designed to meet the conditions of the ring-shaped conductance sensors,and completed the design of signal processing module.In order to obtain the quantitative relationship between the gas holdup and the output voltage signal of the sensor,the signal processing module is designed according to the characteristics of the output signal.Through the Lab VIEW development environment is used to collect and process the signal.Based on the physical and static calibration of the ring-shaped conductance sensor,the relationship curves of the gas flow rate and the dimensionless voltage value are obtained.In the U-shaped pipeline system,inside diameter 0.05 m,the angle of inclination angle 25 degree,4.5m long,several typical flow patterns are simulated and the dynamic test is carried out in the actual flow state.The gas holdup measured by the measurement system is basically the same as the calibration curve.