油气两相文丘里流量计测量灵敏度分析

Sensitivity Analysis of Oil and Gas Two-phase Venturi Flowmeter

油气两相文丘里流量计对气液两相流的流型有很好的调整作用,测量结果准确,且能适应苛刻的操作环境。然而关于流量计测量灵敏度的研究却很少。为此,在介绍文丘里流量计工作原理的基础上,建立了文丘里流量计流场数值计算模型,分析了流速、压力、收缩锥角、直径比和喉部取压位置对压差比和虚高修正系数的影响;借助正交试验综合分析了结构参数对文丘里流量计灵敏度的影响,得出了流量计的最优结构参数。分析结果表明:流体在文丘里管的入口直管段静压值缓慢降低;进入收缩段后静压值迅速下降,在喉管末端压力最低;流经出口直管段后压力趋于稳定;流速不影响流量计的测量灵敏度,其他参数对压差比与液相质量分数关系式中的斜率影响显著,从而影响流量计的测量灵敏度。所得结论可为文丘里流量计的结构优化提供参考。

The oil and gas two-phase Venturi flowmeter has a good adjustment effect on the flow pattern of gas-liquid two-phase flow. And the measurement results are accurate and it can adapt to the harsh operating envi-ronment. However, there are few researches about the measurement sensitivity of the flowmeter. The working prin-ciple of the Venturi flowmeter is introduced, a numerical model of the flow field of the Venturi flowmeter is estab-lished. The effect of the flow field, pressure, taper angle, diameter ratio and pressure measurement position at the throat on the pressure drop ratio and the over-reading correction factor are analyzed. The influence of each structural parameter on the Venturi flowmeter sensitivity was comprehensively analyzed by orthogonal test . The optimal structur-al parameters of the flowmeter were obtained. The results show that the hydrostatic pressure at the inlet of the Venturi tube decreases slowly. The hydrostatic pressure decreases rapidly at the inlet and the pressure at the end of the throat is the lowest. The pressure tends to be steady after passing through the straight section of the oudet. The flow velocity does not affect flowmeter measurement sensitivity . The other parameters have significant impacts on the pressure difference ratio and the slope of the liquid mass fraction relationship, thus affecting the flowmeter measurement sensi-tivity . The conclusions obtained could provide references for the structural optimization of Venturi flowmeter.