Measurement Of Gas-liquid Flow Research Articles

Phase fraction measurement of gas-liquid flow based on cyclonic capacitive sensor (CCS) and inverse drift flux method

Abstract As the demand for clean energy sources like natural gas increases, the need for methods to measure the phase fraction of gas-liquid two-phase flows, which have complex and variable flow patterns, becomes more pronounced. This study introduces a phase fraction measurement method based on a cyclonic capacitive sensor. An effective phase fraction prediction model for the gas-liquid flow measurement section is established based on the capacitive signals. Using the drift flux principle, the dimensionless drift velocity of the spiral annular flow is analyzed, and a volume gas fraction (GVF) prediction model based on the ‘inverse drift flux method’ is established. Experimental results show that this method is suitable for a wide range of phase fraction measurements and is highly accurate. When the liquid volume fraction (LVF) is less than 10%, the average relative error of the predicted GVF is 0.3%; for the LVF from 10% to 30%, the average relative error is 1.4%.

A New Device for Gas-Liquid Flow Measurements Relying on Forced Annular Flow

A New Device for Gas-Liquid Flow Measurements Relying on Forced Annular Flow

Measurement of gas-liquid flows with the combination of thermal sensors and conductance sensor

Gas-liquid two-phase flow is a typical phenomenon in energy and industrial production. Thus, flow measurement of gas-liquid flow is vital in the exploration and extraction of oil and natural gas. The thermal sensors are based on convection heat transfer between heating elements and fluid. These sensors have been widely used in flow measurement because of their high precision, and low-pressure loss, and it is not affected by fluid conductivity and viscosity. This study utilized the thermal conductivity difference in liquid and gas to design a measurement system that combines thermal sensors and a conductance sensor. Among them, the thermal sensors contain 2 upstream and downstream thermal resistors and a total of 28 thermocouples distributed over 7 sections (4 for each section) to capture axial and sectional thermal information. A rotating electric field conductance sensor (REFCS) serves to accurately determine gas holdups. The model tests show that the separated flow models have better accuracy than the liquid-phase acceleration models and pressure drop models. Inspired by the classical separated flow models, an improved heat transfer model based on flow patterns is developed by adding an additional superficial velocity term. Based on the mechanism that the heat transfer is dominated by the liquid phase, the superficial velocities are measured in combination with the drift-flux model. Overall, the average absolute percentage deviations (AAPD) for both the heat transfer coefficients and superficial velocities are less than 5%, indicating that the improved model has excellent performance and robustness for flow prediction in 20 mm pipes.

The Gas-Liquid Flow Rate Measurement Based on Multisensors and Machine Learning

Gas-liquid two-phase flow non-separation measurement plays a crucial role in industrial production and two-phase flow theory research. In this paper, an intelligent multi-sensing system is designed for horizontal gas-liquid flow measurement, which integrates near-infrared (NIR), differential pressure (DP) and acoustic emission (AE) technology. The interaction and disturbance information of the gas-liquid phase are detection by the AE and NIR sensors, and then transformed into the form and margin factor which reflect the void fraction and flow rate of gas liquid flow respectively. Both of them are input as feature variables into the least absolute shrinkage and selection operator (LASSO) machine learning model for predicting the liquid phase volume fraction, and the best fusion solution is proposed. The Analysis and evaluation have been conducted in several classic correlations, and the Collins correlation is selected to optimize by LASSO optimization algorithm. The prediction accuracy is improved by 7.14% compared to the Collins correlation, and the MAPE for liquid mass flow rate of slug flow was 8.75% and 89.47% of the predictions were within 20% relative error.

Velocity bias in intrusive gas-liquid flow measurements

Gas–liquid flows occur in many natural environments such as breaking waves, river rapids and human-made systems, including nuclear reactors and water treatment or conveyance infrastructure. Such two-phase flows are commonly investigated using phase-detection intrusive probes, yielding velocities that are considered to be directly representative of bubble velocities. Using different state-of-the-art instruments and analysis algorithms, we show that bubble–probe interactions lead to an underestimation of the real bubble velocity due to surface tension. To overcome this velocity bias, a correction method is formulated based on a force balance on the bubble. The proposed methodology allows to assess the bubble–probe interaction bias for various types of gas-liquid flows and to recover the undisturbed real bubble velocity. We show that the velocity bias is strong in laboratory scale investigations and therefore may affect the extrapolation of results to full scale. The correction method increases the accuracy of bubble velocity estimations, thereby enabling a deeper understanding of fundamental gas-liquid flow processes.

Influence of probe geometry on the characteristics of optical fiber gas-liquid two-phase flow measurement signals.

A conical tip-shaped plastic optical fiber sensor for gas-liquid flow measurement is described. Experimental results show that a distinctive spike signal occurs before the output signal when using a conventional conical fiber probe, whereas this spike signal was greatly suppressed when a cleaved probe is used. A full simulation is implemented based on a three-dimensional ray-tracing method providing a means of comparison with theoretical analysis. The results show that an appropriately cleaved tip provides a promising method of enhancing the bubble measurement signal-to-noise ratio.

Research on entrainment characteristics and Over-Reading model for gas-liquid flow in Venturi

The accurate measurement of gas-liquid flow is becoming increasingly significant in the oil and gas industry. Over-Reading (OR) model is the foundation for the gas-liquid flow measurement using Venturi. In this paper, a new OR model based on the form of Chisholm model for horizontal Venturi has been developed. The relationship between entrainment rate and OR in the throat of Venturi has been considered, which could be linked by the gas-liquid velocity slip. The liquid film thickness and entrainment rate in the throat of Venturi were measured by the conductance probes and cross-correlation method. The laboratory experiments of OR were conducted under the pressures of 0.2–1.4 MPa and at a wider range of Lockhart-Martinelli parameter (XLM:0–1.794). Without piecewise modeling, the relative errors of the new OR model are less than ±5% at the confidence level of 99.1%. The extension of the new OR model has been verified by the published data set of De Leeuw.

A study on over-reading model for gas-liquid flow based on vertical Venturi

The accurate measurement of gas-liquid flow has great significance in industrial production, especially for natural gas. Venturi is a kind of differential pressure flowmeter which is widely used in gas-liquid flow measurement and the differential pressure would be higher in the gas-liquid flow than the gas alone due to the existence of the liquid. This phenomenon is termed as overreading(OR). In this paper, a modified model based on De Leeuw OR model has been proposed. Most studies of OR (including De Leeuw’s) were based on the horizontally mounted flowmeters, however this model was modified for the vertically mounted Venturi. The experiment was carried out with a low range of pressure (0.6-1.2 MPa)and relatively wider range of liquid content (compared to wet gas XLM < 0.3, this experiment XLM = 0.04 − 1.14). The relative error of OR predicted by the modified model was within 5% at the confidence level of 90%. According to the data analysis, this modified model could be a better choice for vertically mounted Venturi than the existing OR models.

Visible measurement of gas-liquid two-phase flow in aircraft engine

Visible measurement of gas-liquid two-phase flow in aircraft engine

Influence of the operation pressure on slug length in near horizontal gas–liquid pipe flow

Slug flow is commonly observed in gas production offshore fields. At high operation pressure only short hydrodynamic slugs are observed. However, as the offshore fields become older, the operation pressure becomes lower and long slugs may form. At near atmospheric pressures the long slugs may reach a size of 500 pipe diameters or more. Such slugs can cause serious operational failures due to the strong fluctuating pressure. Identifying the operation pressure conditions at which the long slugs appear, may reduce or prevent these negative effects. In this paper we process and analyse gas–liquid flow measurements in order to investigate the different slug types and their sensitivity to the operation pressure. The measurements were performed in a 103 m long pipe with an internal diameter of 0.069 m and an inclination of −0.1° from the horizontal. Three types of slugs were categorized according to the difference in liquid levels (liquid excess) between the slug front and tail. The long slugs were found to have the largest liquid excess after formation, whereas the hydrodynamic slugs had no liquid excess. The analysis of the measurements provides a detailed overview on the effect of pressure on the long slug length, and a safe operation region where long slugs will not appear.

Intrusive Effect of Wire Mesh Tomography on Gas-liquid Flow Measurement

To investigate the accuracy of wire mesh tomography (WMT) for gas-liquid flow measurement, the experimental study focused on its intrusive feature has been carried out. The WMT principle is based on the dependency upon electrical conductivity on the local void fraction. The applied wire mesh sensor (WMS) consists of two measuring planes. Each plane has 8x32 crossing points with spatial resolution of2.22x3.03 mm2 and wire diameter of 0.125 mm. The disturbance level is estimated from the deviation of flow properties between each measuring plane of WMT and also from the alternative image processing for low gas intensity range. The results show the dependency of disturbance level on the void fraction shape. Furthermore, the contribution of deceleration and deformation on the flow disturbance related to the flow condition are presented. In addition, the capability of gas velocity evaluation method is confirmed and the intrusive effect becomes only one important parameter for gas velocity measurement.

Intrusive Effect of Wire Mesh Tomography on Gas-liquid Flow Measurement

To investigate the accuracy of wire mesh tomography (WMT) for gas-liquid flow measurement, the experimental study focused on its intrusive feature has been carried out. The WMT principle is based on the dependency upon electrical conductivity on the local void fraction. The applied wire mesh sensor (WMS) consists of two measuring planes. Each plane has 8x32 crossing points with spatial resolution of2.22x3.03 mm2 and wire diameter of 0.125 mm. The disturbance level is estimated from the deviation of flow properties between each measuring plane of WMT and also from the alternative image processing for low gas intensity range. The results show the dependency of disturbance level on the void fraction shape. Furthermore, the contribution of deceleration and deformation on the flow disturbance related to the flow condition are presented. In addition, the capability of gas velocity evaluation method is confirmed and the intrusive effect becomes only one important parameter for gas velocity measurement.

Skill-based interpretation of noisy probe signals enhanced with a genetic algorithm

The paper presents the design and evaluation of an adaptive signal processing procedure based on human skill. The focus is on interpreting probe signals detected in gas–liquid flow in the presence of noise where existing signal interpretation techniques may encounter difficulties. Interpretation of a probe signal requires construction of a corresponding two-state signal that denotes the presence of the phases, i.e. gas and liquid, at the probe tip. To develop a computer procedure that would imitate a skilled operator in probe signal interpretation, manual knowledge acquisition and evolutionary optimization were employed. First, a prototype signal interpretation procedure based on operator skill was designed, and the procedure parameters were then optimized with a genetic algorithm. In the optimization process, a two-state signal reconstructed from the probe signal by an operator was used as a reference. The robustness of the approach was tested in a series of numerical experiments. They included local evaluation on training and test signals, calculation of global void fraction values, and an assessment of variability among different experts. The results showed that the developed technique is highly consistent with the operator way of signal interpretation and represents a reliable prerequisite for gas–liquid flow measurements.

Electrodiffusional diagnostics of gas-liquid flows: Techniques and instrumentation

Application of the electrodiffusional method to gas-liquid flow studies is described. Problems connected with the use of small-size probes, gas-liquid interphase detection and multichannel measurements are discussed. A brief description of the electronic equipment is given and some results of gas-liquid flow measurements are presented.

Measurement of Gas-Liquid Flow in Vertical Two-Phase Flow

Measurement of Gas-Liquid Flow in Vertical Two-Phase Flow