基于文丘里的湿气流量测量实验研究

Experimental Study on Venturi in Wet Gas Flow Measurement

摘要:

对可应用于民用湿天然气流量测量的小口径文丘里管进行了实验研究。通过一台气流式雾化器用氮气把水雾化成湿气，再通过一台入口直径6mm，直径比0.567的文丘里管进行在线流量测量，获得了一定工况参数范围内不同压力、气体密度弗鲁德系数和洛克哈特-马蒂内利参数下的湿气虚高特性数据。分析了洛克哈特-马蒂内利参数、气液密度比、气体密度弗鲁德系数、韦伯数和液气体积比对湿气虚高修正系数的影响。调研了基于差压流量计的7种虚高指数修正关系式，并根据实验数据改进了R-H关系式。提出了针对小口径文丘里测量湿气的气相流量计算模型。实验结果表明，在压力0.5~2.0 MPa，气体密度弗鲁德系数1.0~8.5，洛克哈特-马蒂内利参数0~0.34, 气相体积比95%~100%范围内，该模型修正的气相流量相对误差小于士2.1%，气相均方根误差为1.2%，优于其他模型的修正结果。

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.