Wet Gas Metering Using Double Differential Pressure Flowmeter

The gas-liquid two phase flow phenomena are very common in many fields of industries.As a particular subset of gas-liquid two phase flow, wet gas is widely exists in industries such as petroleum, natural gas, chemical engineering, energy sources, metallurgy, pipeline transport and medicine engineering etc.. So it is of great importance to accurately measure the individual flow rates of each constiuent real time.Here, wet gas metering is the main taskin this research. After discover the wet gas metering characteristics of cone and venturi flowmeters respectively, a novel prototype of double pressure differential device composed of one cone and one venture tube is presented and a new method to measure the individual flow rates is advanced without any conditioning, as well as partial- and full separation. The mainly research works are as follows.1. Studying on the permanent pressure loss of differential pressure flowmeters, and the difference of permanent pressure loss of Vcone flowmeters in terms of single phase flow condition and wet gas flow condition.2. On the basis of comparing the difference of wet gas metering characteristics of cone and venturi flowmeter, a new method of wet gas metering is obtained. Deriving from the mechanism of the difference of"overreading", The design of the double differential pressure device is optimized successfully and two wet gas metering system were completed.3. Analyzing the individual influence of liquid ratio, Froude number and pressure on the wet gas metering characteristics of the double differential pressure device. On the basis of experiment, the Deleeuw overreading model can be modified, and the overreading model of Vcone flowmeters with two beta ratio can be achieved.4. Comparing the metering accuracy of gas flow rates with liquid flow rates of Vcone flowmeter and venturi flowmeter, venturi flowmeter illustrates a higher accuracy for liquid flow rates metering and Vcone flowmeter, a higher accuracy for gas flow rates metering. A new metering algorithm by iterating the overreading model is presented. The experimental results show that the mean relative error of gas flow rates is less than±1% and full scale error of liquid rates, less than±10% over the gas volume fate(GVF) from 99% to 100%.