Research On The Measurement Technology Of Wet Gas Flow Based On Flow Regulation

Wet natural gas refers to natural gas whose liquid phase volume flow does not exceed 10%.It is widely found in petroleum,chemical and other industrial processes.Accurate and reliable measurement of its flow rate is of great significance to industrial production.Nowadays,separation metering methods are widely used in various oil fields.However,separators are very bulky and expensive,as a result,for flow rate measurement of low-production natural gas single well and other low-cost measurement occations,wet gas measurement systems with good performance of simplicity,reliability,low-cost,and high-precision are urgent demanded.In view of this demand,research on wet natural gas flow metering technology will be carried out in this work hoping to explore new technologies for measuring the wet natural gas flow rate without separation.The idea of this work is to adjust the flow pattern of the gas-liquid two phase flow firstly,then measure the flow rate of the two phase fluids.That is,considering that the flow in the wet natural gas pipeline appears annular flow pattern and stratified flow pattern mostly,it is proposed to use a convergent nozzle and a screen to adjust the above-mentioned wet airflow patterns to a quasi-homogeneous flow,and then measure the flow rate using a combination method of ultrasonic flow meter and other flow meters.Based on the above ideas,a wet gas flow experimental measuring device is designed on the gas-liquid two-phase flow measuring platform.The ultrasonicventuri flowmeter and the ultrasonic-target flowmeter on the vertical pipeline are studied.In the thesis,measurement principles of the two combination methods of ultrasonic flowmeter-venturi flow-meter and ultrasonic flowmeter-target flowmeter are analyzed.The over-reading characteristics of single-phase measurements of ultrasonic,venturi,and target flow-meters has been proposed.It was found that the over-reading response curves of the three flowmeters with L-M parameter are different,but there is some commonality,that is,the flowmeter measures overreading grows with the L-M parameter increasing.On the other hand,the gas phase apparent velocity has little effect on the over-reading value.The experimental results of the two combination methods show that the wet gas measurement technology based on flow-regulation can realize gas-liquid two-phase flowrate measurement.In the ultrasonic-target combination,the relative error for gas flow rate measurement is less than 5%,and that of the liquid phase within 15% for most points.For the ultrasonic-venturi flow meter combination,the relative error of the gas flow rate measurement is within 6%,and that of the liquid phase is within 20%.Because the measurement for liquid phase is obtained by gas phase error correcting and the liquid volume fraction is relatively very low,the error value is larger.Comparing the two combination schemes,the ultrasonic-target flow meter scheme is more accurate and worthy of further study.