Holdup Measurements Research Articles

Influence of the gas phase on a large-scale bubble column fluid dynamics: Gas holdup, flow regime transitions, and bubble size distributions

We present the results of an experimental study of a large-diameter bubble column operating in batch mode with air or CO2 as the gas phase and water as the liquid phase. The bubble column has an inner diameter of 0.24 m and is 5.3 m in height. The superficial gas velocity varied between 0.0037 m/s and 0.0233 m/s. The experimental investigation consists of gas holdup measurements and image analysis. Flow regime transitions were detected by gas holdup measurements, and image analysis was used to investigate the bubble size distributions. The results suggest that the homogeneous flow regime is stabilized when CO2 is used as the gas phase. The gas holdup is higher for the CO2-water system at fixed superficial gas velocity, especially in the heterogeneous flow regime. In the homogeneous flow regime, the mean bubble diameter and the fraction of large bubbles are lower for the CO2-water system, explaining the higher gas holdup.

Insulating Material with Scale Components for High-Temperature and High-Pressure Water Applications.

Accurately measuring water holdup in horizontal wells is crucial for effectively using heavy oil reservoirs. The capacitance method is among the most widely used and accurate techniques. However, the absence of suitable insulating materials at high temperatures and pressures limits the effectiveness of capacitive water holdup measurement in heavy oil thermal recovery. This study introduces a new composite material based on an aviation-grade, special glass glaze as the insulating medium doped with inorganic components (CaSO4, MgSO4, Ca(OH)2, and SiO2). This new composite material demonstrates outstanding insulating performance under high-temperature and high-pressure conditions in water. A water environment with a high temperature of 350 °C and a pressure of 12 MPa considerably enhances the composite material's insulation. After 72 h of continuous use, the insulation performance remains 0.3 MΩ. The layers exhibit improved insulation and stability, maintaining integrity through five consecutive temperature shocks in 500 °C air and 20 °C water. XRD, IR, SEM, and TEM analyses reveal that the new composite material is amorphous after firing and that the addition of inorganic components improves the bonding between the glass glaze components and contributes to a denser structure. Simultaneously, SEM and TEM analyses indicate that adding inorganic components results in a smoother, crack-free, and more compact surface of the special glass glaze. This enhancement is crucial for the material's long-term stability in high-temperature and high-pressure water environments.

A novel method for holdup measurement of three phases by an ultrasonic device with the flexible substrate

The precise measurement of multiphase flow holds significant importance across diverse industrial contexts. However, rigid probes struggle with the variable dimensions of curved surfaces, while flexible probes are hindered by fragility, susceptibility, and challenges in large-scale production. Herein, we propose an ultrasonic device featuring a flexible substrate that seamlessly amalgamates flexibility and rigidity to enable precise measurement of three-phase flow. Through simulation, we determine the optimal ultrasonic frequency (1 MHz) and flexible substrate thickness (3 mm) for a specified probe and pipe size (20 mm). A novel concept, the specific attenuation coefficient (SAC), derived from the voltage-amplitude of transmitted and received signals and propagation distance, is introduced to differentiate between oil and water. The discrepancy between measured and actual three-phase holdups are 0.55 %, 0.36 %, and 0.59 % for water, gas and oil, respectively, with a variance of measurement results 0.027.

Numerical and experimental investigation on droplet entrainment mechanism and closed equations of two-fluid model

As a clean and low-carbon energy source, natural gas is an important force in achieving carbon peaking and carbon neutrality goals. Affected by the strong force of gas and liquid during mining and transportation, it exhibits the phenomenon of droplet entrainment. Entrained droplets change the properties of gas and liquid phases, which is crucial for accurate measurement of liquid film thickness, gas holdup, pressure drop and flow rates in natural gas pipelines. The measurement of entrained droplets has always been a focus and difficulty in the two-phase flow research field. Therefore, numerical simulation combined with experimental measurement are presented to study the droplet entrainment mechanism and closed equations of two-fluid model. The specific parameter settings for simulating horizontal gas–liquid annular flow based on numerical method are discussed, and effective simulation of droplet entrainment and deposition in annular flow is achieved. By comparing liquid film thickness and wave velocity from the simulation results with the experimental results, the correctness of the simulation method is verified. Then, the mechanism and dynamic evolution process of entrained droplets in annular flow are revealed, and the generation and deposition characteristics of entrained droplets are studied. As a result, the closed equations of two-fluid model such as droplet velocity, gas–liquid interface velocity, and gas–liquid interface friction factor are established. The proposed two-fluid model is validated using dual mode ultrasound and differential pressure sensors, demonstrating its good applicability and extrapolation.

Measurement method of gas holdup in horizontal gas-liquid two-phase flow based on fiber-optic probe array

Aiming at the problem of gas holdup measurement in horizontal shale gas wells with low flow rates, a fiber-optic probe array sensor for horizontal gas-liquid stratified flow is designed and developed. The Fluent fluid volume method is used to establish a simulation model of gas-liquid two-phase flow in the horizontal collecting pipe, and a study on the flow characteristics and flow patterns in the gas-liquid two-phase flow in the horizontal collecting pipe with low gas flow is carried out. Based on the acquisition of the fluid flow pattern is stratified flow characteristics, the design of the fiber-optic probe array structure with different numbers and positions of the probes, and the fiber-optic probe array sensor is modeled using the ZEMAX ray tracing software, simulation analysis of its response characteristics in different flow patterns and the array structure selection. Finally, based on the above research, the fiber-optic probe array sensor for gas holdup measurement is designed and developed, and the platform for gas-liquid two-phase flow is constructed and experimentally verified. The experimental results show that the developed fiber-optic probe array sensor has good applicability for gas holdup measurement under stratified flow, and the error of the measurement does not exceed 0.1.

Measurement of Gas Holdup in Slug Region of Horizontal Oil–Gas–Water Three-Phase Flow by a Distributed Ultrasonic Sensor

Measurement of Gas Holdup in Slug Region of Horizontal Oil–Gas–Water Three-Phase Flow by a Distributed Ultrasonic Sensor

A modelling workflow for quantification of photobioreactor performance

In this work we have developed a comprehensive modelling workflow for the quantification of photobioreactor performance. Computational Fluid Dynamics (CFD) modelling combined with Lagrangian particle tracking was used to characterise the flow field inside the reactor; this information was combined with a Monte-Carlo model of light attenuation and a kinetic growth model to predict the performance of the system over the duration of the entire batch. The CFD model was validated against measurements of the overall hold-up, local hold-up and mixing time for superficial velocities between 0.6 and 6 cm s−1 in a pilot-scale bubble column photobioreactor, with the CFD predictions agreeing with the experimental data. Comparison was also made between the predicted biomass concentration and experimental measurements using the diatom Phaeodactylum tricornutum, with the model predictions being in good agreement with the experimental results. The model was used to investigate a range of operating conditions and reactor designs, with the most promising predicted to give a 40 % increase in the biomass productivity. Results from this work can be used for the in-silico design and optimisation of photobioreactor systems, thereby enabling their wider use as a sustainable production technology.

Water Holdup Measurement in Oil–Water Flows With Staggered Double Helix Microwave Sensor

Water Holdup Measurement in Oil–Water Flows With Staggered Double Helix Microwave Sensor

Fluctuation analysis and spatial distribution model of particle concentration in a lab-scale scrubbing-cooling chamber

The motion and distribution of ash from coal gasification during the scrubbing and cooling process are crucial for revealing the fluid flow pattern and improving the efficiency of multiphase separation. Experimental measurements of the local solid holdup (εs) in the liquid pool of a laboratory-scale gas-liquid-solid three-phase scrubbing-cooling chamber were carried out using an optical fiber probe. The fluctuations of εs in time and frequency domains under different operating conditions were discussed. The axial and radial distribution of εs was quantitatively analyzed. The results showed that inter-particle collision and particle-fluid interaction are the key factors leading to a fluctuation in particle concentration. Axial uniformity of particle concentration can be quantified by solid-phase volume fraction, particle Reynolds number, Archimedes number, and Morton number; εs in different regions is expressed according to the degree of influence of bubble wake as a correlation equation consisting only of cross-sectional average solid holdup and dimensionless radial position; a dimensionless expression for εs concerning operating conditions was established.

Phases distribution in slurry bubble columns: Insights from single-source computed tomography and gas holdup measurements

In this study, a cylindrical stainless-steel column with dimensions of 250 cm in height and 16.2 cm in diameter was employed to investigate how fluid properties influence phase distribution within slurry bubble columns. The research focused on various superficial gas velocities and operating pressures. Data collection was carried out using single-source Computed Tomography and overall gas holdup. The gas holdup was found to be directly proportional to both the superficial gas velocity and the operating pressure. Results revealed that both liquid properties and operating pressure have a considerable impact on flow regime transition. Interestingly, when comparing water to Therminol LT, higher gas holdup measurements were observed when water was used, displaying a relative difference of approximately 29% in the bubbly flow regime under ambient conditions. The effect of liquid properties on holdup profiles became more pronounced at high pressures. For example, under higher pressure conditions, Therminol LT exhibited a higher gas holdup rate due to its lower viscosity and surface tension, leading to an increased rate of bubble breakup. While the influence of physical properties on the solids' holdup profile was relatively less significant, it remained noteworthy when compared to its impact on the gas holdup profile.

Design of sudden contraction return bend pipe for the measurement of holdup and fouling characteristics: a CFD analysis

Design of sudden contraction return bend pipe for the measurement of holdup and fouling characteristics: a CFD analysis

Microwave transmission method for the detection of water holdup in oil-water mixtures based on a Yagi antenna

In this paper, Yagi antennas are introduced into microwave transmission measuring instruments as the transmit and receive antennas for detecting moisture content in oil-water mixtures. A Yagi antenna is designed, where the simulation results show a peak gain of 9 dBi and the reflection coefficient S11 is lower than ???10 dB in a frequency band of 2.25-4 GHz. Meanwhile, the measurement result using a vector network analyser shows that the Yagi antenna works in the frequency band of 2.9-4.15 GHz, indicating that measurement results shifted to high frequencies. Based on the Yagi antennas, a moisture content measuring system using the microwave transmission method is designed and constructed, where the measurement results show the Yagi directional high-gain microwave antenna used in this paper can achieve water holdup measurement in the range of 0-100%, where the relative error is less than ??15% and the absolute error is within ??2.341%.

Research on Liquid Flow Rate Detection of Mixed Fluid Based on Vibration Signal Characteristic Analysis of Gas Liquid Two-Phase Flow

The online detection of liquid flow rate in gas-liquid two-phase flow has become an important factor in ensuring the safe operation of gas wells. In this paper, the real-time measurement of liquid holdup in gas-liquid two-phase flow is carried out by analyzing the characteristics of vibration signals excited by gas-liquid two-phase flow impacting on the pipe wall. Firstly, an acceleration sensing detection and processing system is constructed to obtain the vibration signals excited by gas-liquid two-phase flow impacting on the pipe wall. Then, the pure airflow vibration signals at different flow velocities and the gas-liquid two-phase flow excitation vibration signals at different liquid flow rates are tested, respectively, and the time-frequency characteristics analysis based on STFT is implemented. The practice shows the following: firstly, the frequency band of 6.5−15 Hz is identified as the characteristic frequency band of liquid flow rate in gas-liquid two-phase flow. Secondly, the liquid holdup is positively correlated with the vibration energy in its characteristic frequency band. Thirdly, a mathematical model of the relationship between liquid flow rate and vibration energy is constructed. Finally, the measurement error of liquid holdup is within 10%. This research method has laid a good foundation for the subsequent detection of characteristic parameters of each phase in gas-solid-liquid complex multiphase flow fluids, and it has certain application and promotion value.

Comparison Between 180° and 360° Double Helix Capacitance Sensors for Measuring Water Holdup of Horizontal Oil–Water Stratified Flows

Flows of two immiscible liquids in horizontal pipes are often encountered in the petroleum industry. The complicated flow structures, which appear in horizontal oil–water two-phase flow, bring a great challenge to flow measurement. In this article, to investigate the feasibility of the double helix capacitance sensors for measuring the water holdup of the horizontal oil–water two-phase flow, the finite-element method (FEM) is applied to analyze the sensitivity distributions of the sensors with the helical angles of 180° and 360°. Then, a horizontal oil–water two-phase flow test system is built. An experimental study is performed to compare the water holdup measurement characteristics of the two different double helix capacitance sensors. Overall, the 180° double helix capacitance sensor is found to have better characteristics in the measurement of water holdup. The conclusion is supported by the sensor sensitivity compensation characteristics analysis with the FEM. Based on the measurement of water holdup, an experimental correlation is established between the water holdup and the water cut, and better results are obtained in the water cut prediction.

Performance model evaluation of turbine flow meter in vertical gas-liquid two-phase flows

Aiming at the need for flow measurement of gas-liquid flows in domestic gas well production, this paper proposes a measurement method based on the combination of the turbine flow meter (TFM) and a rotating electric field conductance sensor (REFCS). In experiments, the REFCS is used for the measurement of the gas holdup. To verify the applicability of the TFM models investigated in the previous study, for the modeling part, the mass, momentum and torque models are evaluated in vertical upward gas-liquid two-phase flows. In our model test, the meter factor model of TFM considers the effects of the slip ratio between the gas and liquid phases and flow patterns. In particular, the gas holdup involved in calculating the slip ratio in the model evaluation is obtained from the REFCS measurements. Model test results show the torque model has better volumetric flow rate prediction accuracy than the mass and momentum models. In the present study, the ranges of the liquid and gas phases are Qw = 2–30 m3/d and Qg = 1–16 m3/d, it was found that the average absolute deviation (AAD) in the predicted volume flow rate is equal to 1.23 m3/d and the average absolute percentage deviation (AAPD) is equal to 7.69%. The evaluated results presented in this paper will allow better estimates of the volumetric flow rates of gas-liquid flows based on the combined TMF and REFCS measurements during the monitoring of gas well production.

A New Online Monitoring Method for Water-in-Oil Droplet Based Microfluidic Devices

The online water-in-oil (w/o) droplet monitoring is essential for the uniformity of the droplet based microfluidic devices. In this work, a contactless impedance detection (CID) method for online w/o droplet monitoring in microfluidic devices is proposed. In the proposed method, a new CID sensor, which can work at low working frequency and overcome the unfavorable influence of coupling capacitance, is developed to obtain the impedance information of the w/o droplet. Based on the obtained impedance information, measurement models are established to realize online measurement of drop length and dispersed phase holdup. Then the coefficients of variation (CVs) of the two measured parameters are calculated to evaluate the uniformity of the droplets for online monitoring. Online monitoring experiments of w/o droplet were carried out in a microfluidic device with a 500 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}\,\,\times $ </tex-math></inline-formula> 500 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\mu \text{m}$ </tex-math></inline-formula> microchannel. The experimental results verify the effectiveness of the proposed droplet monitoring method. The developed CID sensor can realize impedance measurement at a working frequency lower than 50kHz. The drop length and dispersed phase holdup are useful parameters for online monitoring of droplets. With the established measurement models, the maximum relative error of droplet length measurement is less than 10% in the droplet length range of 1.5mm-3.5mm. And the maximum error of dispersed phase holdup measurement is less than 5% in the dispersed phase holdup range of 0.20-0.67.

Multiphase holdup measurement of oil-gas-water flow using new dual receiver fiber-optical probe array multiphase logging tool.

To solve the problem of multiphase holdup measurement, a new dual-receiver fiber-optical probe array multiphase logging tool (NDRFOPA_MLT) is designed and developed. This paper first constructed the mechanism model of an NDRFOP for phase holdup measurement by using the ray tracing method and theoretically analyzed the feasibility of NDRFOP to measure phase holdup; considering the shortcomings of NDRFOP local measurement, a NDRFOPA sensor for oil production three-phase flow is designed and developed. At the same time, the volume of fluid model was used to simulate the distribution characteristics of the medium in the NDRFOPA_MLT measurement pipeline under the working conditions of oil-gas-water flow with a total flow rate range of 0.42-1.25m3/h, water holdup range of 50%-80%, oil holdup range of 10%-30%, and gas holdup range of 10%-40%. In addition, the NDRFOPA_MLT measurement models for different multiphase flow conditions were established by the ZEMAX ray tracing method, and the sensitivity distribution, response characteristics, and phase holdup measurement methods were studied to obtain the phase holdup measurement results under multiphase flow conditions. Finally, a multiphase flow experimental platform with a measurement pipe diameter of 20mm and a measurement pipe length of 300mm was established, and experiments were conducted under multiphase flow conditions, such as a gas flow rate range of 0.04-0.16m3/h, oil flow rate range of 0.64-1.70m3/h, and water flow rate range of 0.53-2.58m3/h. The experimental results showed that phase holdup measurement error was mainly kept within 10%.

Application of Array Imaging Algorithm in Horizontal Well Oil–Water Two-Phase Water Holdup Measurement

Due to the effect of gravity differentiation in nonvertical wells and the asymmetry of the space around the wellbore, the fluid flow pattern in the wellborn will change greatly. The water holdup reflects the distribution of water, which lays a foundation for understanding the proportion of oil and gas. Water holdup imaging can intuitively reflect the distribution of each phase and the overall water holdup. In this article, with No. 10 industrial white oil and tap water as the working medium, the local water holdup value was measured in the oil–water two-phase by the capacitance array tool (CAT), and then, the response characteristics of the instrument were analyzed. MATLAB software is used to interpolate the local water holdup data of the array in the oil–water two-phase of the horizontal well. The interpolation algorithms used include bilinear interpolation, cubic spline interpolation, simple inverse distance weighted interpolation, and Gaussian radial basis function (GRBF) interpolation. The results show that the water holdup measured by the CAT shows a good measurement effect at low and medium flow rates. Linear and cubic splines are selected in the case of low flow rate and low water cut in the oil–water two-phase flow with stratified flow pattern. The GRBF is selected under the condition of low flow rate and high water cut. The GRBF was selected under different water cut conditions of middle and high flow rates with dispersed flow pattern.

Intensified gas-liquid mixing in bioreactors equipped with a dual coaxial mixer containing biopolymer solutions

One of the significant challenges in the efficient operation of bioreactors is uniform gas dispersion in very viscous non-Newtonian fluids because of the complex rheology exhibited by these fluids. The uneven gas distribution is more pronounced when large-scale aerated bioreactors with aspect ratios of higher than one are utilized. Prior studies have shown that using a close clearance anchor and two centrally positioned impellers in gas-liquid coaxial mixers can improve gas dispersion in pseudoplastic fluids. Nonetheless, despite the extensive applications of yield-pseudoplastic fluids in many industries, no research has been conducted on the gas dispersion in yield-pseudoplastic fluids within a dual coaxial bioreactor with a greater-than-one aspect ratio. In this regard, electrical resistance tomography (ERT) and computational fluid dynamics (CFD) were employed to assess the effect of operating parameters, namely central impeller speed, anchor speed, aeration rate, rotating mode, and pumping mode of central impeller on the aeration efficiency in yield-pseudoplastic fluids. The experimental measurement of the overall gas hold-up affirmed the profound impact of using a close clearance anchor. Even though the down-pumping and co-rotational mode at Na = 30 rpm provided the highest aeration efficiency, more uniform gas dispersion was observed at Na = 10 rpm owing to a greater axial velocity in the downward direction and more effective circulation loops. Compared to the downward pumping direction, lower gas hold-up values were obtained for the up-pumping configurations. Finally, the superiority of the down-pumping and co-rotational mode was demonstrated by comparing the aeration efficiency of various mixing configurations.

Measurement of Transient Flash Evaporation Flow in Liquefied Gas Propulsion Using Dual-Plane ECT

In this paper, the transient flash evaporation flow in liquified gas propulsion (LGP) was measured using a dual-plane electrical capacitance tomography (ECT) sensor. The novelty mainly stems from a selection method for more accurate liquid holdup measurement, a constrained adaptive cross-correlation algorithm for more stable velocity, and compensation methods against the changes of temperature and pressure. By the selection method, inter-electrodes capacitances that contribute less to the flow measurement, are removed from each data frame and more accurate liquid holdup is derived via image reconstruction. The adaptive cross-correlation algorithm with a constraint on the correlation coefficient is adopted to alleviate the adverse effect of the fast changes of flow pattern on the velocity measurement. Then, the compensation methods are realized by correcting the deviations of phase density and permittivity caused by dramatic temperature and pressures changes. Simulations and experiments validated the effectiveness of the proposed methods to derive the mass flow rate of the two-phase flow via the measured liquid holdup, flow velocity and estimated phase density. It is shown that the remaining mass of propellant in the storage tank calculated from the mass flow rate is in good agreement with the measured reference by the electronic balance, where the average relative errors under different initial pressures are less than 10%. As the best of our knowledge, this is the first-time of transient flash evaporation flow measurement in a lab-built LGP device, which is promising to be applied for the effective online control to maximize the output impulse of LGP and estimate the remaining life of small spacecrafts.