Investigate On The Measurement Characteristics Of Wet Gas Based On Slotted Orifice And Vortex Procession Flowmeter

Wet gas flow is a gas-liquid two phase flow with low liquid fractions; Research on wet gas meter is in the underway stage in our country, and it is one of the major unsolved problems for oil and gas industry.Based on a self developed prototype of wet gas meter and experimental data set, a series of works have been carried out. On the basis of previous works, this thesis aims at frequency extraction of wet gas flow, and the metering algorithm by slotted orifice and vortex procession flowmeter is modified and improved.This thesis consists of two parts. The first part is mainly focus on frequency extraction method of vortex precession flowmeter. The second part shows the study on the metering characteristics of slotted orifice and Vortex Procession Flowmeter, and a correlation by slotted orifice differential pressure and vortex precession frequency is established.Based on vortex precession frequency signals, a frequency extraction method by use of Duffing oscillator to obtain frequency signal in noisy background is studied. Simulations validate feasibility of the method and then actual frequency signals of vortex precession flowmeter are processed. When the main frequency can not be obtained by the above method, how to determine the frequency value is also discussed.Based on differential pressure signals from slotted orifices, changing ofΦg with XLM is studied. Then XLM, Frg andβare introduced to modify Lin.Z.H correlation and the accuracy is raised. The relationship between flow rate and vortex procession frequency is also studied and the measurement range of vortex precession flowmeter for liquid flow is expanded from 0.2-1.0 m3/h to 0.2-1.8 m3/h. Further more, the flow metering formula for slotted orifice combined with vortex precession flowmeter is developed and it can be used to get the gas-phase flow with XLM unknown.