A measurement method of slug flow velocity of gas-liquid two-phase flow in horizontal pipe

Abstract

Slug flow is an important flow regime of gas/liquid two-phase flow. The parameters measurements of slug flow are of great importance in scientific and engineering field. Local crosscorrelation method is put forward in this paper to make the mixed velocity measurement of slug flow. Different from normal cross-correlation method, this local cross-correlation make direct use of electrode voltage data and gives detail velocity information of the cross-section. According to the electrode distribution in the pipe cross-section, the excitation manners have been sorted into 3 kinds and measured electrodes have been cut into 9 sorts. A static experiment is carried out to testify and concretely analyze the sensitivity difference of different excitation manners and different located measuring electrodes. Results of static experiment verify the above sorting manner and show that different excitation manner and different measured area has its own apparent data feature and. In this local cross correlation method, only selected electrode pairs instead of all electrodes as normal data process participate in excitation process. So the system efficiency has improved, and as a consequence the velocity resolution of cross correlation is improved. The dynamic experiment result shows the efficiency of this local crosscorrelation method and the experiment error is within 10%.

Identification of horizontal slug flow structures for application in selective cross-correlation metering

“…The results, overall, show correlation between measurements and theoretical predictions for all methods, with method 4 producing the most reliable linear trend. Firstly, the conventional method (1) gives a relatively good linear trend, though variation is reasonably large, and comparable to results from other non-intrusive devices [22,8]. Method (2) gives a similar trend but with some data points with larger variation, this can be explained due to unstable slugs having a more profound effect on the measurement when considered individually.…”

“…The result shows a good linear trend, where the majority of data points are well within a +/-5% error range, and close resemblance to the prediction. Measured points at the lower values of mixture superficial velocity (<2m/s) appear to have slightly higher error margins, as seen by Zhang and Dong [22], though more data would be required to confirm this. Such results are comparable to advanced metering methods such as ultrasonic doppler sensors [9] which measure the actual velocity of fluid particles.…”

“…The application of the discussed methods to recover the mixture velocity has been achieved using a range of instrumentation, although the specific correlation techniques tend to be similar. Zhang and Dong [22] used a resistance based tomography device and cross correlated the raw voltage data, as opposed to a reconstructed image, obtaining an error margin of 10% with a noticeably better accuracy for mixture velocities less than 2m/s. However, their method included using sample data to construct a coefficient matrix to assist the measurement.…”

“…Reis and Goldstein [23] achieved a greater accuracy for a larger range of mixture velocities for steady points using a capacitance method, though tests conducted near the flow regime transition zone gave large discrepancies, which were attributed to velocity discontinuities along the gas / liquid flow. Ahmed [24], also used a capacitance sensor for investigation of slug flows, obtaining a more reliable linear trend between slug translational velocity and mixture velocity but with a noticeable deviation for higher mixture velocities, as with Zhang and Dong [22], as well as for low tested values of mixture velocity (< 0.5m/s). Van Hout et al [5] went further to analyse the effect of pipe inclination angle on such measurements, and successfully derived a model to account for dispersed bubble within the liquid slug region, achieving an overall a prediction within 15% of the measured flowrates.…”

Energy Demodulation Algorithm for Flow Velocity Measurement of Oil-Gas-Water Three-Phase Flow

“…The oil-gaswater three-phase flow, as a multiphase flow of a fluid form, is prevalent in the oil and gas industry. The present research of multiphase flow field, especially the research on measurement technology of oil-gas-water three-phase flow at home and abroad, has become one of the most important topics in the researches of multiphase flow [2,3]. For the three-phase flow of industrial production system, most parameters of oilgas-water three-phase flow are with unpredictable characteristics.…”