Research On The Model Of Coriolis Flowmeter Measuring Gas-liquid Stratified Flow

Now more and more gas-liquid two-phase flow calculation problems are encountered inindustries, the study of the parameters for process control and safe operation is of greatsignificance. Coriolis Flowmeters win a wide range of applications in the petrochemical,storage and offloading and other fields, which make us begin to consider the use of them intogas-liquid two-phase flow measurement, but practical results are not ideal, they show largeerrors. No model was made that can fully simulate this measurement state. Application ofCoriolis flowmeters in gas-liquid two-phase flow is severely restricted and also the onlinecontrol and safe operation of oil, chemical and other processes.In order to successfully applied Coriolis flowmeter to the gas-liquid two-phase flowmeasurement, preliminary exploration and research according to the measurement ofgas-liquid two-phase flow were done in this thesis. Research on the mechanism model wasdone based on the split-phase two-fluid model, and the measuring tube, air, water were forceanalyzed, the vibration equations as well as the frequency of the vibration tube formula ofgas-liquid two-phase stratified smooth flow were derived. The validity of the model wasexplored by comparison with experimental data，the results showed that the vibrationfrequency relative error was within10%in the case of high gas rate (about99%). On the basisof the theoretical and experimental studies, the causes of error of the vibration frequency wereanalyzed, to provide information for theory research and selection of Coriolis mass flowmeterdesign. And the time difference calculation at both ends of the meter when measuringstratified smooth flow was derived, preliminary exploring the mechanism of the gas-liquidtwo-phase flow measurement，and providing a basis for further study. The main conclusionsinclude: 1. Void fraction can be obtained in the case of gas-liquid phase volume flow with knowngas volume, liquid volume and kinematic viscosities, and it is consistent with the actualvariation.2. The oscillation frequency of measuring tube is relevant with the structure and voidfraction and so on.3. The absolute relative errors between the frequencies from the model and theexperiment are within10%, indicating that the frequency model has some applicability forgas-liquid two-phase flow.4. For laminar stratified gas-liquid flow, time difference increases with the increase ofmass flow of gas-liquid two-phase flow.