Holdup Measurements Research Articles

Effect of superhydrophobic surfaces on bubble column flow dynamics

Bubbly flow in bubble column reactors promotes mixing necessary for many chemical processes. We show that if superhydrophobic-coated material is introduced into a bubble column, there can be a substantial difference in gas holdup and earlier initiation of churn-turbulent flow which can alter larger-scale mixing without a need to change the superficial gas velocity. Addition of superhydrophobic surface can also cause bubbles to (directly or indirectly assisted by the surface) escape faster to the free surface resulting in a reduced void fraction (i.e., reduced gas holdup). As the flow becomes optically opaque at few percent gas phase volume fraction, we utilize two dual plane wire mesh sensors to obtain velocity profiles and bubble size distributions, in addition to the traditional pressure and level based gas holdup measurements to calculate average phase fraction. Additionally, a custom build photon-counting dual energy threshold X-ray computed tomography system is employed to get a higher resolution measurement of the time average phase fraction non-intrusively. We report satisfactory agreement between these techniques with differences arising for understood reasons, and use the insight thus yielded to discuss the effect of superhydrophobic surfaces on bubble column flow dynamics.

Measurement of solids holdup in a gas–solid fluidized bed: an experimental, statistical and ANN approach

Measurement of solids holdup in a gas–solid fluidized bed: an experimental, statistical and ANN approach

Multiphase Measurement of Oil Production Using Fiber-Conductance Dual-Mode Sensor

To meet the actual requirements of multi-phase measurement, a fiber-conductance dual-mode sensor (FCDMS) is designed and developed. The theoretical model of the FCDMS measurement field is established, and the light transmission process’s mathematical description and simulation analysis in the sensitive conical tip is carried out. Thereafter, The FCDMS simulation model is established by the ZEMAX ray-tracing method and Finite Element Method (FEM). the effects of structural parameters on sensitivity distribution are analyzed, including the electrode length, the radius of the electrode, and the cone angle of the sensitive tip. Furthermore, we studied the response characteristics of FCDMS in oil-gas-water multi-phase flow. At the same time, the temperature influence experiments and dynamic experiments validate the designed FCDMS, indicating the FCDMS enables measuring the phase holdup of oil-gas-water multi-phase flow. The developed FCDMS could realize the phase holdup measurement with the liquid flow rate range of 10-70m³/d, the gas flow rate range of 5-40m³/d and the liquid water holdup range of 50-90%.

A New Method for Measuring Water Holdup of Oil-Water Two-Phase Flow in Horizontal Wells

The production profile logging technology of Oil-water two-phase flow is an important support technology for efficient development of horizontal oil wells. Moreover, the water holdup of Oil-water two-phase flow is one of the important dynamic measurement parameters for production profile logging technology. Flow patterns in horizontal oil wells are more complex than those in vertical oil wells, making water holdup measurements more difficult. In China, horizontal oil wells are characterized by low liquid production, high water cut and layered development; hence, the concentrating flow logging scheme is adopted to reduce the effects of flow patterns on measurement. In this paper, we proposed a new method of measuring water holdup of Oil-water two-phase flow for the production profile logging in horizontal oil wells. Firstly, the structure of water holdup sensors and the measuring principle of water holdup were introduced. Secondly, the dynamic test research was carried out on the horizontal well simulation facility by using the test prototype of the water holdup measurement method of Oil-water two-phase flow. Additionally, the response characteristics of water holdup sensors at five inclined angles were emphatically discussed. Finally, the measurement error of water holdup was calculated and evaluated in detail. Experimental results show that the absolute values of measurement error of water holdup are less than 5% while the total flow rate ranged from 10 m3/d to 200 m3/d, and the water cut ranged from 30% to 90%, respectively.

Evaluación hidrodinámica de un reactor airlift de recirculación interna con fluidos newtonianos y adelgazantes: Experimentación vs Simulación CFD

The hydrodynamics of an internal-loop airlift reactor was numerically and experimentally characterized. The gas holdup, liquid velocity, shear rate, flow pattern and volumetric oxygen transfer coefficient (kLa) were evaluated as a function of the air velocity and medium rheology. Tap water and CMC solutions were used as Newtonian and non-Newtonian fluids, respectively. The standard  model was employed for modeling turbulence, and unsteady three-dimensional simulations with the Euler–Euler model were performed. Gas holdup, liquid velocity and kLa measurements were performed for validating simulations. An increase in bubble coalescence and a decrease in kLa was observed with CMC solutions. The presence of recirculation loops inside the riser for CMC solutions is reported, which was not observed with tap water. The higher the CMC concentration, the larger the recirculation region seems to be. Results show that recirculation loops play a substantial role in the reactor’s hydrodynamic performance, and it turns out that the gas holdup in the riser increases with increasing the CMC concentration.

A new approach to measure gas holdup in industrial flotation Machines. Part III: Industrial prototype design and assessment

• An industrial gas holdup sensor prototype was validated in a 250 m 3 flotation cell at Los Pelambres. • A weakly dependence of sensoŕs discharge coefficient to Reynolds number was observed. • Gas holdup predictions were largely insensitive to errors in the anticipated pulp kinematic viscosity. • Submersible sensor provided robust accurate gas holdup measurement over long periods of time. An industrial gas holdup sensor was designed, constructed, and its performance assessed on a 250 m 3 self-aerated Wemco cell at Los Pelambres concentrator. The submersible sensor comprised a ceramic-liner IP68 magnetic flowmeter assembled to a stainless steel gas exclusion cell, which resembles an inverted truncated cone. The gas exclusion cell was designed to avoid low-velocity sections where particles could settle. When the sensor device is vertically immersed in an aerated pulp a continuous downward flow of pulp without bubbles is induced through it. A remotely installed processing unit converts the flow velocity signal, provided by the magnetic meter, into a gas holdup signal, by applying Bernoullís equation to the induced flow. The ideal velocity in the Bernoullís equation is obtained by multiplying the measured velocity and the discharge coefficient. The discharge coefficient was found to be fairly constant over a wide range of Reynolds numbers. Gas holdup measurements were compared against those obtained by sampling a fixed volume of aerated pulp using the JK Tech Air Holdup Probe. These tests were conducted on different days over nine months to allow for the pulp properties to change. Gas holdup changes in the flotation machine were achieved by restricting the air intake to the cell by placing a stainless steel cap on top of the air suction pipe. Short and long-term testing demonstrated the sensoŕs capability to provide reliable and accurate continuous-time gas holdup measurements for industrial flotation machines.

Liquid holdup measurement for gas-liquid stratified flows by means of resistive probes and image processing

Flow patterns exert a fundamental influence on the behaviour of multiphase flows, and they must be brought into play when dealing with their modelling. This is usually done by means of summarizing quantities as the phase holdups and the interfacial area concentration. Many techniques have been designed during the years to measure them, among which the use of probes relying on electrical resistance is one of the simplest and less expensive. While having these points of strength, resistive probes are intrusive devices. This work is therefore devoted to a comparison between liquid height (and derived quantities) measurements – for stratified and stratified-wavy air-water flows – performed using a conventional resistive probe and by means of an image-based technique. Validation of the latter was performed using computer-generated flow images. Then, an experimental campaign was carried out for flows with liquid superficial velocities in the range 0.03 ÷ 0.06 m/s and gas superficial velocities in the range 0.77 ÷ 2.31 m/s. Results showed that the two methods give answers within very few percent of difference, which is more than satisfactory in this field. The results are also in good agreement with some of the most credited literature models and correlations.

Modelling of ultrasonic method for measuring gas holdup of Oil-Gas-Water three phase flows

In oil–gas-water three-phase flow, the presence of two physically distinct dispersed phases leads to complex interfacial effects and relative velocities between the phases, which poses a significant challenges for gas holdup measurements. In this paper, a novel gas holdup measurement based on flow structure detection is realized. Firstly, the effect of gas bubble diameter on ultrasonic attenuation was studied, and a gas bubble diameter-based ultrasonic gas holdup measurement model was proposed. According to the model's specifications, a combined measurement system consisting of pulse transmission ultrasonic sensor and bi-optical fiber probe sensor was built. The dynamic experiment of oil–gas-water three-phase flow was conducted on a simulated well installation to measure the gas holdup using the combined measurement system. The results suggest that the proposed ultrasonic-optical measurement system can attain a high level of measuring precision.

Measurements of Local Flow Characteristics in a Gas–Liquid–Solid Circulating Fluidized Bed with Immersed Telocentric Photography

The gas bubble size, local phase holdup, and other local flow characteristic parameters of the gas–liquid–solid circulating fluidized bed play an important role in the design and operation of this type of reactor. However, due to the limitation of measurement techniques of three-phase fluidization, the local flow characteristics have not been well measured and studied. In recent years, telecentric imaging technology has been applied in other multiphase systems, and a new telecentric probe method has been used to measure the local flow characteristics of a gas–liquid–solid expanded bed. In this work, the measuring method was introduced to measure the local phase holdups and bubble size distributions of the three-phase circulating fluidized bed. Concurrently, the influence of the superficial liquid and gas velocities on the particle circulation rate in the three-phase circulating fluidized bed was studied. The method reliability of gas holdup and bubble size measurements was validated by a conductivity probe method. The results provided basic data of such a reactor for future flow numerical simulations and industrial applications.

Study on measurement model of cross section holdup based on array ultrasonic sensor

This paper is based on the working principle of the array ultrasonic sensor and the principle of the array ultrasonic sensor in the measurement of the gas-liquid two-phase flow section holdup. An image reconstruction of the pipeline section is derived through the coordinate transformation of the data matrix points. Based on the image characteristics, the average section gas holdup measurement model of three flow patterns is proposed. The volumetric gas holdup was established by using the section gas holdup obtained by the model. Compared to the real volume gas holdup, the absolute error was within ±11%, indicating that the model is of high accuracy.

Measurement of Water Holdup in Vertical Upward Oil-Water Two-Phase Flow Pipes Using a Helical Capacitance Sensor.

Oil–water two-phase flows widely exist in industrial production, especially in the petroleum industry. The liquid holdup is significant for understanding reservoir production characteristics and improving oil recovery. This paper focuses on the helical capacitance sensor for the measurement of water holdup of oil–water two-phase flows. A new double helix capacitance sensor with an electrode rotation angle of 360° is designed. The sensitivity field distribution of the sensor with different parameters is simulated by the finite element analysis method, and the optimal geometric size of the sensor is obtained. The measurement characteristics of the sensor under different flow conditions are investigated by dynamical experiments of vertical oil–water flows. By analyzing the response signal of the helical capacitance sensor, the flow pattern can be identified, and the apparent water holdup can be calculated. The results show that the proposed sensor is suitable to measure the water holdup in a wide range of water cuts. Even in flow conditions of a high water cut, the sensor still retains good resolution in the D O/W flow pattern. This study expands the water holdup measurement of a capacitance sensor in the case of an oil–water two-phase flow with a high water cut.

External Wetting Efficiency in a Three-Phase Fixed Bed Loaded with Porous and Non-Porous Packings

Films and rivulets are the two basic forms of dynamic liquid in a three-phase fixed bed (trickle bed), which determines the wetting efficiency of the catalyst. This paper is devoted to the conflicting wetting performance observed between non-porous glass beads and less wettable porous alumina, and a parallel zone model is applied to resolve the complex liquid flow texture. It shows in both cases of glass beads and aluminium pellets, the pressure drop, film flow and rivulet flow fractions all display pronounced multiplicities along with the liquid flow rates in increasing and decreasing branches, although the rivulet flow fraction is reduced to 0 in the liquid decreasing branch started from pulsing flow in both cases. Different from the glass beads, there is almost no wetting efficiency difference for the alumina pellets with respect to liquid flow rate increasing or decreasing, which is in agreement with the dynamic liquid holdup measurements. The liquid is significantly more uniformly distributed over the crosssection in the Al2O3 bed since rivulet flow is much reduced than in the case of glass beads.

Measurement of High Water Holdup in Oil-in-Water Flows Using Reticular Microwave Resonant Sensor

Long-term waterflooding exploitation leads to the low flow rate and high water cut of the oil-water flows in oil wells, which has put forward a new challenge for water holdup measurement. Therefore, a reticular microwave resonant sensor (RMRS) is proposed in this paper, which can realize high-sensitive water holdup measurement of oil-in-water flows with high water cut and low velocity at 1.85 GHz-2.3 GHz. Due to the optimum design in quasi-TEM mode of the sensor based on finite element method, the resonant frequency shift measured by the RMRS are sufficiently sensitive to water holdup. After the viability of the sensor confirmed through simulation experiment, a sensor prototype is prepared. And the measurement characteristics of the sensor to water holdup is firstly investigated by static experiment. Subsequently, the dynamic experiment of vertical upward oil-in-water flows is carried out. The response characteristics of the RMRS with the change of water salinity, flow rate and water cut are analyzed. Finally, a satisfactory relationship between resonant frequency and water holdup with the consideration of water salinity is obtained. It shows that the RMRS has a good resolution to water holdup. Moreover, it can effectively restrain the influence of water salinity.

Gas Holdup Measurement of Horizontal Gas-Liquid Two-Phase Flows by Using a Novel Combined Ultrasonic-Conductance Sensor

Horizontal gas-liquid two-phase flows widely exist in petroleum, chemical, and other important industrial fields. The flow structures forming during gas-liquid flows can be complex. The transition between flow patterns greatly depends on many factors, such as the fluid properties and the flow rate. Notably, there are multi-scale flow structures even in the same flow pattern. Therefore, it is a great challenge to accurately measure the gas holdup in the horizontal gas-liquid flows by single-mode sensor technology. In this study, we designed a novel combined ultrasonic-conductance sensor (CUCS) consisting of a multi-electrode conductance sensor (MCS) and a transmission ultrasonic sensor (TUS). A flow pattern map of the horizontal gas-liquid flow was obtained in the experiment, and the responses of the CUCS under different flow patterns were collected. The stratified smooth (ST) flow, stratified wavy (SW) flow, and Taylor bubbles in intermittent flow were visualized by the MCS, and the corresponding measurement model of the gas holdup was presented. For the slug region (SR) in intermittent flow, a physical model for measuring the gas holdup was established based on the attenuation characteristics of the transmitted ultrasonic wave. The result indicates that the CUCS has a higher measurement accuracy for the gas holdup of the horizontal gas-liquid flows with different flow patterns.

A Distributed Conductance Cross-Correlation Method for Measuring Low-Velocity and High Water-Cut Oil-Water Flows

Oil-water two-phase flow widely exists in the oil production and transportation. The flow pattern presents obvious complexity due to non-uniform distribution of water and oil. When the onshore oilfields are on a middle-late stage of oil recovery, the oil production gradually decreases and the water-cut increases. Accurate measurement of oil-water two-phase flow is a significant issue to improve oil production performance and optimize oil reservoir management. Therefore, we propose a distributed four-sector conductance cross-correlation sensor to realize the flow pattern classification and the measurement of flow velocity and water holdup for low-velocity and high water-cut oil-water flows in a 20 mm inner diameter pipe. The geometry dimension is optimized according to the sensitive field distributions of the sensor. In the flow loop test of vertical upward oil-water two-phase flow, the output signals measured from upstream and downstream electrodes are used to figure out three flow patterns combining with a high-speed camera, and the cross-correlation velocity. Then we use the kinematic wave theory to connect the relationship between the cross-correlation flow velocity and the mixture flow velocity considering water- cut and flow patterns. In addition, according to Maxwell equation, we calculate the water holdup. Finally, a drift velocity model based on three flow patterns is constructed to measure the oil phase superficial velocity.

Area‐alterable liquid electrode capacitance sensor for water holdup measurement in oil–water two‐phase flow

AbstractOil–water two‐phase flow exists widely in the process of petroleum industry. The water holdup is an important parameter but difficult to measure. In this paper, we develop an area‐alterable liquid electrode capacitance sensor for water holdup measurement in oil–water two‐phase flow. The capacitance sensor has a relatively high measurement sensitivity and a good linearity in the full range of the water holdup, from 0% to 100%. Meanwhile, a firing technology of insulating layer is presented to guarantee the characteristics of the capacitance sensor with high temperature resistance, corrosion resistance, and non‐stickiness. The static performance of the capacitance sensor is validated theoretically and experimentally. Vertical upward oil–water two‐phase flow experiments indicate that the developed capacitance sensor has good performance for water holdup measurement with average relative error of 10% in the full range of the water holdup. Based on the output signal of the sensor, the information of flow structure can be also estimated in different flow patterns.

Holdup Measurements of Aqueous Foam Flows and Flow Regime Characterization through Image Processing

Summary One of the most critical issues in the oil and gas industry is the dewatering of the pipelines used for natural gas transportation, and foam injection seems to be a prominent solution. This work has two goals: The main one concerns the development of an optical tool to measure the liquid holdup in foamy flows and perform the flow regime characterization, whereas the secondary goal is to quantify the effectiveness of surfactant injection in reducing the liquid loading. In this paper, we present the results of an experimental campaign aimed at the characterization of gas-liquid-foam flows in a horizontal pipe. Initially, liquid loading measurements for gas and liquid superficial velocities, ranging from 0.41 to 2.30 m/s and from 0.03 to 0.06 m/s, respectively, were performed by means of a specifically developed optical method. For each liquid superficial velocity, the minimum liquid holdup was found to lie in the proximity of the boundary between plug and stratified flow regime, with a superficial gas velocity between 0.44 and 0.90 m/s. Hence, the plug flow region corresponds to the best operating condition to perform the pipeline dewatering procedure. Moreover, the drift-flux model usually adopted for ordinary two-phase gas-liquid flows seems to fit well with the measured values of void fraction.

Micromixing Efficiency in the Presence of an Inert Gas in a Rotor–Stator Spinning Disk Reactor

The effects on micromixing of co-feeding an inert gas with the bulk liquid are studied for a rotor–stator spinning disk reactor by means of the Villermaux–Dushman test reaction. The results of varying rotational speeds and gas–liquid ratios are reported for three configurations: injecting the acid into the dispersed region, into the bottom thin-film region, and into the upper thin-film region. The results show that injecting in the dispersed region is the optimal configuration, as the liquid experiences the shear stress between the rotor and the stator, and with increasing rotational speed, micromixing efficiency subsequently increases. Injecting in the thin-film regions leads to poor micromixing efficiency, since the gas layer reduces the turbulence levels experienced by the liquid. For the bottom thin film, increasing rotational speed improves micromixing efficiency due to inertial rotation of the liquid film. However, in the upper thin film, micromixing is significantly worse, being affected by the dripping of liquid on the stator at the injection point. Gas holdup measurements are compared to previous studies, showing that most of the gas volume is present in the thin-film regions. These results are relevant for the design of modular chemical processes using the spinning disk technology, when fast competitive chemical reactions occur in the presence of gas and liquid.

Measurement of water holdup in oil-in-water emulsions in wellbores using microwave resonance sensor

Measurement of water holdup in oil-in-water emulsions in wellbores using microwave resonance sensor

A flow rate measurement method for horizontal oil-gas-water three-phase flows based on Venturi meter, blind tee, and gamma-ray attenuation

Online horizontal oil-gas-water three-phase flow rate monitoring is essential for reliable operations during industrial production. A flow rate measurement method is developed in horizontal oil-gas-water three-phase flows by combining a blind tee, a Venturi meter, and a gamma-ray densitometer. The blind tee is installed at the test section entrance to homogenize the mixture by transforming the horizontal flow to a vertical upward flow. The Venturi meter is used for the total flow rate measurement. The dual-energy gamma-ray densitometer is used for phase holdup measurement. In the present method, blind-tee mixing effects and oil-water mixture slip behavior is essential, which were experimentally analyzed in this work. The phase inversion was found in the oil-water mixture with the increasing of the oil volume fraction. Besides, the addition of the gas reduces the oil-water slip ratio. For the range of 0–35% and 65–100% oil fraction in the oil-water liquid, the oil-water mixture can be well treated as a pseudo homogenous liquid with a slip ratio of 0.9–1.1. A three-phase flow rate model is then established for these conditions. The method was validated by horizontal oil-gas-water three-phase flows with average relative errors of 3.2% for the total flow rates, 4.3% for the gas flow rates, 11.5% for the oil flow rates, and 7.8% for the water flow rates.