In-tube Separation And Flow Rate Measurement Of Gas-liquid Two Phase Flow

Gas-liquid two-phase flow is frequently encountered in many fields such as petroleum,chemical,nuclear energy and so on.It's inevitable to measure their flow rate where exits two-phase flow.Compared with single-phase flow,one of the most striking aspects of two-phase flow is the strong volatility and randomness,so the instruments that worked in two-phase flow are in the extremely unstable state.At the same time,with the rapid development of oil-gas management,it's harder to measure multi-phase flow accurately.Therefore,it's significant for industrial development and multi-phase metering system to research a new generation of gas-liquid two phase flow measurement device and method.This paper proposed a novel on-line metering method of multi-phase flow,which has the advantage of both separation and non-separation methods.First,a swirl vane is mounted in the inner pipe to transform inlet flow pattern into gas-liquid swirling annular flow.Then,the liquid film and the velocity profile are instantaneously measured by Doppler velocimetry(UDV).Next,the ring surface integral method is adopted to calculate the liquid phase mass flow.The velocity of gas is measured by a L shape pitot tube,and the mass flow rate of gas is obtained according to mass conversation equation.FLUENT numerical simulation and experiments were conducted during the research.The influence of different rectifier devices on distribution of liquid film in the downstream was studied under the same condition.The separation efficiency affected by of the rectifier device was analyzed.Then the flow pattern adjustment device was chosen.Experiments were carried out in an air-water two-phase flow loop,the working fluids are air and water.A short transparent section of the pipe,made of Plexiglas,was mounted upstream of the test section for flow pattern observation.The superficial liquid velocity varied from 0.03 to 0.39 m/s,while the gas superficial velocity was in the range of 3.39 to 17.79 m/s.The test section mainly consisted of a swirl vane,UDV,pitot tube and data acquisition system.Ultrasonic probe was affixedto the outer surface of the glass pipe,which has a distance of 40 millimeters with rectifier.The pitot tube was mounted at downstream of the probe.The flow patterns of experiment include stratified flow,slug flow and annular flow.The capacitance probe and CAV444 were combined to get liquid film thickness,which was used to compare with the test data acquired by UDV.The experimental results show that,spiral vane can transform different flow patterns in the inlet into gas-liquid swirling annular flow and remove the influence of interface fluctuation on flow rate measurement.Experimental results have shown that,the error of liquid flow rate is less than 10%,while gas flow rate relative error is within 20%.