气泡对电磁流量测量的影响特性研究

Study of the influence of bubbles on electromagnetic flow measurement

电磁流量计在工业生产过程中扮演着重要角色,但易受流体中气泡的影响导致测量结果出现波动进而影响测量精度。定量分析气泡在电磁流量计测量过程中产生影响的规律对提高电磁流量测量精度和实现气液两相流测量具有重要工程意义。针对上述问题,首先从权重函数角度入手,采用解析法建立了气泡尺寸、气泡偏心以及气泡数量对电磁流量测量影响的理论模型;其次,通过仿真和实验研究了管径为100 mm,圆形点电极半径为5 mm的电磁流量系统受气泡不同状态的影响,并采用输出电压灵敏度分析了气泡不同状态下对电磁流量测量的影响规律。研究结果表明,随着气泡尺寸增加其影响大小随之增加,气泡尺寸变化过程中影响在0.3%~5%范围内变化,最大为5%;气泡(直径为10 mm)沿电极方向偏心产生的影响在0.25%~0.6%范围内,且随偏心距离的增加而增加;气泡沿垂直电极方向偏心距离增加产生的影响微小,在-0.2%~0.2%范围内波动;同时,在气泡流动过程中,气泡越靠近电极截面影响越大并在电极截面位置产生影响最大值,单气泡最大值分别为0.18%、0.22%、-0.20%,随着气泡数量增加产生的影响逐渐增加,3气泡和6气泡影响最大值分别为0.36%和2.3%。本研究补充和完善了电磁法测量气液两相流权重函数相关理论,得出气液两相流中气泡不同状态对电磁流量测量系统的影响规律,为提高电磁流量测量检测精度和实现气液两相流电磁测量提供技术支持。

The electromagnetic flowmeter plays an important role in the industrial production.However,easily influenced by the bubbles in the fluid,fluctuations often appear in the measurement results,leading to a lower measurement accuracy.Quantitative analysis of the influence of bubbles in the electromagnetic flowmeter measurement process has important engineering significance for improving the accuracy of electromagnetic flow measurement and realizing gas-liquid two-phase flow measurement.In view of this,starting with the weight function,the analytic method is used to establish the theoretical model of bubble size,bubble eccentricity,and the number of bubbles.Then,by simulation and experiments,the influence of different states of bubbles on the electromagnetic flow system with a diameter of 100 mm and circular point electrodes with a 5 mm radius is studied.The output voltage sensitivity is used to analyze the influence of different states of bubbles on electromagnetic flow measurement.According to the research results,with the increasing of the bubble size,its impact on the electromagnetic flow measurement is within the range of 0.3%~5%,the maximum of 5%.The influence of bubbles with a diameter of 10 mm ranges within 0.25%~0.6%along the eccentricity direction of the electrode and increases with the increasing of the eccentricity distance.The influence of the increasing eccentric distance along the direction perpendicular to the electrode has a tiny impact on the measurement.It fluctuates within-0.2%~0.2%.Meanwhile,with the bubble flow,a shorter distance between the bubbles and the electrode cross-section leads to a larger impact while the impact gets its maximum at the electrode cross-section.The maximum values for a single bubble are 0.18%,0.22%,-0.20%.The influence is enhanced with the increasing in the number of bubbles.The maximum values in the case of 3 bubbles and 6 bubbles are 0.36%and 2.3%.This paper improves the theories related to the weight function of electromagnetic measurement of gas and fluid double-phase flow,obtains the influences of different states of bubbles on the electromagnetic flow measurement system,and provides technical support for the improvement of electromagnetic flow measurement accuracy and realization of gas and fluid double-phase flow.