Abstract:The small-caliber Venturi tube was studied experimentally, which could be applied to the flow measurement of civil wet natural gas. An airflow atomizer was used to atomize water into wet gas with nitrogen, and then a Venturi tube with an inlet diameter of 6 mm and a diameter ratio of 0.567 was used for on-line flow measurement. The wet gas over reading characteristics data of different pressures, gas densiometric Froude numbers and Lockhart-Martinelli parameters within a certain range of operating parameters were obtained. The effects of Lockhart-Martinelli parameter, gas-to-liquid density ratio, gas densiometric Froude number, Weber number and liquid-gas volume ratio on wet gas over-reading correction factor were analyzed. 7 kinds of over-reading exponent correction equations based on differential pressure flowmeter were investigated, and the R-H over-reading exponent correction equation was improved according to the experimental data. A model for calculating gas flow rate in mass of wet gas measured with small-caliber Venturi tube was proposed. The experimental results show that, in the range of pressure 0.5-2.0 MPa, gas densiometric Froude number 1.0-8.5, Lockhart-Martinelli parameter 0-0.34 and gas volume fraction 95%-100%, the relative error range of gas flow rate in mass is ±2.1% and the gas root-mean-square error is 1.2%, which are predicted by this model and better than the results predicted by other models.
