Gas-oil-water three-phase flow is a common phenomenon in the petroleum industry, especially as the oil fields age and water production becomes inevitable. While extensive research has been conducted on gas-liquid two-phase flow, the understanding of gas-oil-water flow remains limited, particularly considering the intricate mixing dynamics between the water and oil phases due to their low interfacial tension (IFT). It is anticipated that the oil-water flow pattern in gas-oil-water three-phase flow can impact the overall pressure drop. We experimentally investigated this phenomenon in a horizontal pipe equipped with a valve that controlled the phase mixing. Restrictions like chokes are commonly utilized in transportation systems for a variety of reasons, such as regulating pressure or flow rates, to ensure safe transportation and meet facility requirements. However, further understanding of their impacts on three-phase flow behavior is still needed. We systematically investigate this issue in this study. The experiments were carried out in a flow loop featuring a 45-ft-long, 2.067-in. horizontal pipe, with a 2-in. ball valve installed at the inlet of the test section. Flow patterns, phase distributions, and pressure drop were measured 123 pipe diameters downstream of the valve in the test section. A high-speed camera and an electrical capacitance volume tomography (ECVT) system were used in the experimental study. Various tests were conducted to systematically study the impact of oil-water flow patterns on the downstream fluid flow behaviors for gas-oil-water three-phase slug flow at different choke openings, water cuts, and flow rate conditions.

This work presents an experimental study on oil–water flow downstream of a restriction. The flow pattern, volumetric phase distribution, and their impacts on pressure drop are discussed. We employed two techniques to visualize the oil–water flow patterns, a high-speed camera and an Electrical Capacitance Volume Tomography (ECVT) system. The ECVT system is a non-intrusive device that measures the volumetric phase distribution at the pipe cross-section with time, which plays a critical role in determining the continuous phase in the oil–water flow, and therefore the oil–water flow pattern. In this study, we delved into the oil–water flow pattern and volumetric phase distribution for different valve openings, flow rates, and water cuts, and how they impact the pressure drop. The experimental results have demonstrated a strong relationship between the oil–water flow pattern and the pressure gradient, while the oil–water flow pattern is significantly influenced by the flowing conditions and the valve openings. The impacts of water cuts on the oil–water flow pattern are more obvious for smaller valve openings. For large valve openings, the oil and water phases tend to be more separated. This results in a moderate variation in the pressure gradient as a function of water cuts. However, it becomes more complex as the valve opening decreases. The pressure gradient generally increases with decreasing valve openings until the flow pattern becomes an oil-in-water dispersed flow. The impact of the valve on the pressure gradient is more pronounced in water-dominated flow when the water cut is above the inversion point, while it seems to be most obvious for medium water cut conditions.

Mass flow rate is a critical measurement parameter when designing cryogenic hydrogen fluid systems. It is important in custody transfer applications for calculating financial obligations, fundamental fluid property research/modeling, and fluid system design applications to optimize chill down performance, maintain thermal equilibriums, and provide feedback control for pumps and valves. However, due to the large temperature differential between cryogenic fluids and the environment, there is often multiphase flow during system chilldown and steady state operation. Current available cryogenic flow measurement techniques are not equipped to deal with the complex multiphase flow inherent in cryogenic fluid systems, resulting in significant measurement errors. This mass flow measurement inaccuracy can cause financial loss, system instability, and even component failure, resulting in a strong market demand for a multiphase cryogenic mass flow meter to optimize and control sophisticated and costly cryogenic systems. This paper presents a solution in the form of a novel capacitance- based technique for measuring the multiphase mass flow rate of cryogenic hydrogen in a terrestrial environment. The device was calibrated and tested on a 1 / 2 " tube multiphase hydrogen flow loop at a cryogenic hydrogen test facility. An error of +/- 2 % full scale was achieved across a range of flow conditions, including transient and steady states.

Cryogenic fluid flow is a critical measurement parameter but is difficult to properly measure due to the extreme environmental conditions and the frequent presence of multiphase flow during saturated liquid transfers. Multiphase flow proves challenging for most flow measurement methodologies; furthermore, additional measurements of volume fraction, quality, and slip velocity are often required. In-line capacitance-based sensors have the potential to overcome these limitations. In this paper, a capacitance sensor in a multiphase cryogenic flow loop is evaluated for its ability to measure liquid volume fraction, gas phase velocity, and total mass flow rate for two-phase cryogenic nitrogen flow.

Abstract Understanding and modeling multiphase flow is of vital importance to the design of next-generation cryogenic systems. While many experiments characterizing multiphase flow have been performed on Earth, the behavior of cryogenic systems still needs to be fully described in low gravity and microgravity conditions. As the necessity of cryogenic systems increases for in-space refueling operations, increased heat transfer efficiency, and in-situ resource utilization, the demand for better fluid models, instrumentation, and control systems also increases. In this paper, a capacitance-based flow regime identification algorithm is developed for use with cryogenic systems. Data is collected on a liquid nitrogen system for a wide array of flow regimes in a ½” tube. Quantitative parameters are developed that are able to determine the real-time multiphase flow regime and the algorithm is verified using accepted models, providing much that is needed for the foundation of a multiphase flow regime identification instrument with broad applications in fluid modeling, research, and cryogenic system feedback control.

While measurement and monitoring of powder/particulate mass flow rate are not essential to the execution of traditional batch pharmaceutical tablet manufacturing, in continuous operation, it is an important additional critical process parameter. It has a key role both in establishing that the process is in a state of control, and as a controlled variable in process control system design. In current continuous tableting line operations, the pharmaceutical community relies on loss-in-weight feeders to monitor and understand upstream powder flow dynamics. However, due to the absence of established sensing technologies for measuring particulate flow rates, the downstream flow of the feeders is monitored and controlled using various indirect strategies. For example, the hopper level of the tablet press is maintained as a controlled process output by adjusting the turret speed of the tablet press, which indirectly controlling the flow rate. This gap in monitoring and control of the critical process flow motivates our investigation of a novel PAT tool, a capacitance-based sensor (ECVT), and its effective integration into the plant-wide control of a direct compaction process. First, the results of stand-alone experimental studies are reported, which confirm that the ECVT sensor can provide real-time measurements of mass flow rate with measurement error within -1.8 ~ 3.3% and with RMSE of 0.1 kg/h over the range of flow rates from 2 to 10 kg/h. The key caveat is that the powder flowability has to be good enough to avoid powder fouling on the transfer line walls. Next, simulation case studies are carried out using a dynamic flowsheet model of a continuous direct compression line implemented in Matlab/Simulink to demonstrate the potential structural and performance advantages in plant-wide process control enabled by mass flow sensing. Finally, experimental studies are performed on a direct compaction pilot plant in which the ECVT sensor is located at the exit of the blender, to confirm that the powder flow can be monitored instantaneously and controlled effectively at the specified setpoint within a plant-wide feedback controller system.

Measurement of phase volume fractions in water-containing multiphase flows is necessary for the optimization of a host of industrial flow processes. Many water-containing multiphase flows can be classified as either water-dispersed or water-continuous mixtures. A recently developed approach based on Hanai’s mixture formula and utilizing electrical capacitance tomography (ECT) sensors have shown good potential for obtaining water volume fraction estimates in two-phase water-containing flows with different water salinity levels. However, the proposed approach was investigated via controlled experiments restricted to static configurations while, in practice, multiphase flows can be dynamic and unpredictable. In this work, we perform a flow loop study of the proposed ECT-based method for volume fraction estimation in oil–water two-phase flows. We evaluate the performance of the proposed method in both water-dispersed and water-continuous flow regimes by employing different types of capacitive sensors in cylindrical arrangements and parallel-plate rectangular arrangements.

Electrical capacitance tomography (ECT) is an extremely versatile and cost-effective technology that is advancing rapidly in multiple dimensions. Industries involved in multiphase flow are constantly looking for the best way to measure and monitor the behavior of their complex processes. ECT's low power, low profile, cost effective, and configurable design allow it to be adapted to some of the most complex multiphase flows and harshest environments, making it a top contender for use in today's most advanced industries. This chapter will explore some of the most recent applications of ECT in industrial tomography and where the technology is heading in the coming years.

Binary mixture fluidization is an important operation type of fluidized bed. The regularity of mixing and segregation of binary mixture is the key to process research and development. In this paper, a new experimental method for the measurement of mixing and segregation of binary mixture is proposed by combining gas cutting -off method and Electrical Capacitance Volume Tomography (ECVT). While inheriting the advantage of high applicability of gas cutting-off method, this method can be of high spatial resolution with the application of ECVT. This combination can not only obtain detailed particle component distribution information, but also reduce the experimental labor intensity. Based on the measuring principle of ECVT and Maxwell Garnett mixing model, the calibration relationship between voxel value and particle mixing ratio was deduced. An experimental binary mixture system was employed to validate the calibration relationship. The result showed that the calculated calibration curve was in good agreement with the experimental calibration curve, which indicates the rationality and feasibility of the method. On this basis, mixing process of the same particle system was quan-titatively characterized and analyzed at a given air flow rate.

Real-time monitoring of water volume fraction in multiphase flows is an important problem for a number of industrial applications. The water phase in the multiphase flows may correspond to either the dispersed phase or the continuous phase. In the past, several low-cost and nonintrusive techniques based on the electrical capacitance tomography (ECT) has been developed to image and monitor in real-time multiphase flows containing water. However, such monitoring becomes increasingly challenging for high salinity levels, and no reliable ECT-based method is presently available which could work for obtaining water volume fraction in multiphase flows for all water salinity levels. In this paper, we propose a new approach based on the Hanai’s formula for complex dielectric constant and taking advantage of the Maxwell-Wagner-Sillars effect to obtain, to a good approximation, water volume fractions in multiphase flows containing water as either dispersed or continuous phase.

The estimation of water volume fraction in water-containing multiphase flows is important for several industrial applications. There are many published works detailing with methods to estimate and monitor water-containing multiphase flows based on different sensor modalities, including electrical capacitance tomography (ECT). A recently developed method based on ECT sensors to estimate the water volume fraction in water-containing two-phase flows utilizes the Hanai’s mixture formula. Fresh or tap water is conductive and has large electrical permittivity, thus making the ECT-based estimation problem highly nonlinear and challenging to solve. Most of these works assume that the mixture state of water in the two-phase flow is known as either continuous or disperse. However, in practice, the state of water might not be known a priori. In this work, we propose a deep learning based approach to classify water-containing flows into water-dispersed or water-continuous flows and to estimate the water volume fraction present in the flow.

Against the background of current and future global challenges, such as climate change, process engineering requires increasingly specific solutions adapted to the respective problem or application, especially in gas–liquid contact apparatuses. One possibility to adjust the conditions in this kind of apparatuses is an intelligent and customized structuring, which leads to consistent fluid properties and flow characteristics within the reactor. In the course of this, the interfacial area for mass transfer, as well as residence times, have to be adjusted and optimized specifically for the respective application. In order to better understand and advance the research on intelligent customized additively manufactured lattice structures (AMLS), the phase distributions and local gas holdups that are essential for mass transfer are investigated for different structures and flow conditions. For the first time a tomographic measurement technique is used, the Electrical Capacitance Volume Tomography (ECVT), and validated with the volume expansion method and a fiber optical needle probe (A2PS-B-POP) for an air-water system for different modes of operation (with or without co-current liquid flow in empty or packed state). The ECVT proved to be particularly useful for both in the empty tube and the packed state and provided new insights into the phase distributions occurring within structured packings, which would have led to significantly underestimated results based on the visual reference measurements, especially for a densely packed additively manufactured lattice structure (5 mm cubic on the tip). Particularly for the modified structures, which were supposed to show local targeted differences, the ECVT was able to resolve the changes locally. The additional use of a pump for co-current flow operation resulted in slightly higher fluctuations within the ECVT data, although local events could still be resolved sufficiently. The final comparison of the empty tube at rest data with a fiber optical needle probe showed that the results were in good agreement and that the local deviations were due to general differences in the respective measurement techniques.

A novel approach to studying dynamic three phase systems using Electrical Capacitance Volume Tomography (ECVT) is proposed and verified against previously published pressure gauge techniques and hydrodynamics patterns. In this three-phase study, hold up of water, glass beads, and air are measured simultaneously in a slurry bubble column reactor. Application of ECVT to investigate three phase systems holds several advantages over pressure gauges including the ability to deliver non-invasive real time direct measurements without making assumptions about the hydrodynamics. Results support the conclusion that ECVT can be used in place of pressure gauges to obtain accurate holdup measurements of three-phase flow systems in real time applications.

Electrical Capacitance Volume Tomography (ECVT) is a real-time 3D imaging and measurement technique for the on-line study of multiphase flow behavior. Here, it is applied for the study of a static three phase oil-water-gas system. A cylindrical test column was constructed and an experiment conducted where the air and water volume fractions were varied in an oil continuous background. An ECVT system was used to capture real-time data about the system and this data was analyzed to determine the volume fraction of the three phases and analyze the systems accuracy in determining these volume fractions.

Displacement Current Phase Tomography (DCPT) is a real-time 3D imaging and measurement technique for the online study of multiphase flow behavior. Here, it is applied for the study of a bubbly, two-phase flow of gas and water. A straight cylindrical column was constructed and an experiment conducted where the air mass flow rate through the column was varied. A DCPT system was used to capture real-time, three-dimensional data about the bubbly flow, and this data was analyzed to determine important factors about the bubbly flow, such as void fraction, bubble size, bubble frequency, and bubble velocity.

Abstract Passive cyclonic gas-liquid separators (PCGLSs) are commonly used in microgravity conditions where gravity settling separation is difficult or impossible. In this study, displacement-current phase tomography (DCPT) is used to measure various features of the gas-liquid flow inside of a PCGLS. The liquid holdup, liquid angular velocity, and gas core size are investigated. The liquid holdup is also measured in a gas-liquid flow that simulates the injection flow for a PCGLS. It is found that the gas core contracts and expands in a periodic motion as air is injected with water. This motion becomes more noticeable as the air flow rate is increased. It is also found that the liquid layer angular velocity has a positive linear trend with the air flow rate under constant water flow rates. A basic linear relation is derived to relate the liquid angular velocity to the air and water flow rates. All DCPT and electrical capacitance phase tomography (ECVT) results closely match the visual confirmation methods used for each flow feature.

A three-dimensional ECVT sensing technique is applied to imaging complex slugging phenomena of a gas–solid fluidized bed under ambient and elevated temperature conditions. The study indicates that the time interval between rising slugs decreases with an increase in the gas velocity, reaching a nearly steady time interval value of about 1 s between two slugs when the gas velocity is ∼1.7 m/s above the minimum fluidization velocity. The fluidized bed behaves as a bubbling fluidized bed at low gas velocities. In slugging regime, the slug rise velocity increases with the gas velocity. A mechanistic analysis of forces around the dense phase solid particles suggests that the relationship between the slug rise velocity and the gas velocity for the square-nosed slugging bed is not strictly linear and is highly related to the interparticle forces, internal friction of particles, and gas velocity in addition to the wall stress.