Accurate Flow Rate Measurement Research Articles

Wet gas over-reading correction for ultrasonic flow meters

Oil and gas operators rely on accurate flow rate measurements to optimize production and generate more from their reservoirs, particularly in wet gas fields. A cost-effective solution for these flow measurements is the use of single-phase measurement technologies with an over-reading correction that corrects the gas flow rate for the presence of the liquid phase. Traditional flow measurement technologies in wet gas fields are Venturi meters and orifice plate meters that involve differential pressure measurements. Over the years, a higher installed base of ultrasonic flow meters is observed in wet gas fields. Ultrasonic flow meters have advantages over conventional wet gas technologies; however, an over-reading correction method for this measurement technology has not yet been derived. The current work is a first attempt to devise a correction method based on a large data set of ultrasonic measurements in horizontal configuration at conditions comparable to field applications. The correction method is a physical model for the gas void fraction and is based on the dominant dimensionless numbers in wet gas flows that originate from the fundamental equations of multiphase flow dynamics. This approach leads to the definition of the over-reading correction in different flow regimes in terms of these dimensionless numbers and is supported by an extensive set of measurement data and evidence from visual observation of the flow patterns. The correction method is capable of correcting the ultrasonic over-reading with a resulting uncertainty of about 4% for a 95% confidence interval for a range of conditions relevant to the oil and gas industry.

Simple and accurate calibration system for Laser Doppler Velocimeters

The calibration of Laser Doppler Velocimeters (LDVs) is of a great importance for the accurate measurement of the fluid flow rate and the speed of moving objects. In this paper, a simple, low-cost and portable calibration system for LDV is introduced. This system, which is based on a commercial optical chopper, can offer calibration uncertainty of (0.048%) (σ = 2) for velocities up to 1914 m/min and dynamic lengths of up to 15.4 km, which is better than the uncertainties reported by similar systems with a much complicated design. Therefore, this calibration system can be implemented easily by any calibration laboratory or even by national metrology institutes.

Modeling of multiphase flow through chokes

The accurate measurement of mass flow rate is of vital importance with respect to production control in gas or oil fields equipped with chokes. A theoretical model to predict the flow regime and mass flow rate of multiphase flow through chokes was developed and derived on the basis of Perkins and Al-safran models. In the present model, the assumption of adiabatic condition between gas and liquid was adopted alternatively when fluids flow through the throat of chokes, which is different from the existing models. The slippage phenomena between gas and liquid have also been taken into consideration in this model. After analyzing, the Schuller slip model was found to be the most appropriate one, which is consistent with the work of Al-safran. Furthermore, the effect of the discharge coefficient Cd on the model calculation accuracy was discussed. The way to calibrate irreversible loss using the optimal discharge coefficient was recommended instead of a constant coefficient, which means that experiment should be carried out for a particular choke before use. Meanwhile, the present model was validated and compared with the models currently used in fields against both subcritical and critical experimental data. The model evaluation demonstrated that the present model was more reliable in predicting the critical pressure ratio yc, especially in large GLR condition. Meanwhile, the statistical error analysis of calculated mass flow rate showed that the average percent error (E1), absolute average error (E2) and standard deviation (E3) were 0.117%, 8.754% and 0.729% for the present model, respectively. Compared to other models, the present model prediction outperforms their predictions a lot. It indicated that the present model was more reasonable and reliable in predicting the mass flow rate of multiphase flow through chokes.

A time-dependent method for the measurement of mass flow rate of gases in microchannels

Accurate measurement methods are required in the analysis of thermodynamic non-equilibrium effects associated with rarefied gas flows. For example, for the specific case of accommodation coefficients measurements, the quantity of interest is often the mass flow rate along the channel. For this purpose, the following paper presents a new time-dependent version of the well-known constant volume method for the accurate measurement of mass flow rates of gases in microchannels. The technique proposed here is an improvement in respect to the classic technique since it can be used for transient experiments. Moreover, it can be applied to configurations with arbitrary upstream and downstream reservoirs dimensions. Particularly, the proposed method relies on the assumption that the flow conductance varies linearly during the experiments and thus the pressure variations in the reservoirs can be fitted by a well-defined exponential function. Then, the instantaneous mass flow rate through the channel can be determined directly from the pressure fitting coefficients. A great advantage of the time-dependent constant volume method is that the measurements can be obtained from a single experiment for a wide range of rarefaction conditions, since the mean pressure between the reservoirs is allowed to change with time. Moreover, this technique represents a convenient manner to provide raw data of pressure variation with time in the reservoirs and transient mass flow rate in the channel by simply providing the fitting coefficients of the theoretically derived functions. A clear geometric criterion is also presented to determine when such mass flow rate measurements can be considered as quasi-steady, corresponding closely to results obtained under steady conditions, when ideally the channel connects two infinite reservoirs at different pressures. Results for flows of nitrogen through a stainless steel microtube (L=92.22±0.01 mm and D=435.5±3.5 µm) were obtained from 118 independent experiments, provided in this work, using two different experimental setups and three different configurations of the system volumes. As expected, no deviation was observed between all experimental campaigns in terms of the reduced mass flow rate. In addition, all results indicate that nitrogen can be considered completely accommodated at the surface of the microtube used, with α=0.986±0.019 when the diffuse-specular gas-surface interaction model is adopted and αt=0.991±0.020 (αn=1) when the Cercignani-Lampis model is adopted.

Flow rate measurement of low GVF gas-liquid two-phase flow with a V-Cone meter

Accurate online measurement of the liquid flow rate in a low GVF gas-liquid two-phase flow is of great importance for engineering and science. In the present study, a cost-effective metering method is developed on the basis of a V-Cone meter. Experiments are carried out in a horizontal test section and the fluids are air and water with GVF of 0–12.2%. The flow characteristics of the V-Cone throttle device with low GVF gas-liquid two-phase flow passing through are investigated. Experiments show that the V-Cone throttle device can modulate the flow pattern and the gas presence in a liquid flow can accelerate the development of the flow downstream of the cone. To correct the gas-induced liquid flow rate prediction error, a dimensionless parameter termed the two-phase mass flow coefficient is proposed. Experimental results indicate that the coefficient is dependent on the gas densiometric Froude number, the liquid densiometric Froude number and the gas-to-liquid density ratio, and the consequent correlation is obtained by data fitting. Besides, the permanent pressure loss of the V-Cone is investigated and a prediction correlation for the two-phase pressure loss is proposed. Finally, by incorporating the two-phase mass flow correlation and the pressure loss correlation, a metering method for the liquid flow rate in a low GVF gas-liquid two-phase flow is developed. The relative error of the liquid mass flow rate predicted by the method is less than ±4.0% at the confidence level of 97.5%. The newly developed metering method provides a high-accuracy as well as cost-effective measurement technology for the industry.

Transit Time Difference Flowmeter for Intravenous Flow Rate Measurement Using 1–3 Piezoelectric Composite Transducers

The flow rate of injected medication implemented by intravenous (IV) systems must be accurately monitored and meticulously controlled to prevent medical accidents. In this paper, an ultrasonic flowmeter (UF) with 1-3 piezoelectric composite transducers was designed, fabricated, and tested on a variety of flow rates of mimic medical injections. The transducer wedge for the angled beam propagation and an acoustic impedance matching layer were included in the design for transmission enhancement. To ensure an accurate measurement of flow rate, the effect of the flow distributions inside the IV tube was taken into account. The developed UF exhibited the capability of detecting low flow rates (<;0.005 m/s), with 1%-2% discrepancy compared with the reference rate of infusion.

Experimental measurement of oil–water two-phase flow by data fusion of electrical tomography sensors and venturi tube

Oil–water two-phase flows are commonly found in the production processes of the petroleum industry. Accurate online measurement of flow rates is crucial to ensure the safety and efficiency of oil exploration and production. A research team from Tsinghua University has developed an experimental apparatus for multiphase flow measurement based on an electrical capacitance tomography (ECT) sensor, an electrical resistance tomography (ERT) sensor, and a venturi tube. This work presents the phase fraction and flow rate measurements of oil–water two-phase flows based on the developed apparatus. Full-range phase fraction can be obtained by the combination of the ECT sensor and the ERT sensor. By data fusion of differential pressures measured by venturi tube and the phase fraction, the total flow rate and single-phase flow rate can be calculated. Dynamic experiments were conducted on the multiphase flow loop in horizontal and vertical pipelines and at various flow rates.

Magnetic Flowmeter for Fast Sodium Reactors

A magnetic flowmeter for liquid sodium is described. The inductor in this device consists of an electromagnet generating a pulsed, low-frequency, magnetic field. The use of a pulsed magnetic field made it possible to separate the informative component of the signal from all electromagnetic interference whose time variation is not a multiple of the frequency of the excitation magnetic field. Thus, all interferences at the industrial frequency and the thermo-emf are eliminated. This increases the accuracy of flow rate measurements significantly and makes it possible to reduce the magnetic field in the channel. The power of the inductor does not exceed 0.5 W. There is no need to adjust the zero point, and it is possible to measure low flow rates and the reverse flow. The physical principles of the method of measurement, the design particulars and technical characteristics of the device, and the results of tests are examined.

Predictor–Corrector Method for Scramjet Inlet Air Mass Flow Rate Measurement

The accurate and real-time measurement of the scramjet inlet air mass flow rate is critical to flight control. To measure the scramjet inlet air mass flow rate, air data parameters are estimated. The inertial-navigation-system-computed air data are real time but not accurate enough. The flush air data sensing system can provide sufficiently accurate estimations of air data parameters, but it is not employed during the flight. This paper proposes a predictor–corrector method. Accurate air data estimations are not required. The scramjet inlet air mass flow rate estimated by the inertial-navigation-system-computed air data is taken as the prediction value. Surface pressure measurements combined with the inertial navigation system provide the correction value. The algorithm is simple enough and can be implemented in real time. Comparing the results of the scramjet inlet air mass flow rate estimated by the inertial navigation system and predictor–corrector method, it is shown that the predictor–corrector method can greatly improve the accuracy of the scramjet inlet air mass flow rate measurement. The scramjet inlet air mass flow rate measurement sensitivity to the freestream static pressure, static temperature, and angle of attack is reduced significantly by the predictor–corrector method.

Characterization of flow homogeneity downstream of a slotted orifice plate in a two-phase flow using electrical resistance tomography

Two-phase flows are complex and unpredictable in nature, commonly encountered in a majority of fluid transport systems. The accurate measurement of two-phase flow is critical for a wide range of applications from wet stream to multiphase flows. There are different methods to meter two-phase flow in various industries. One approach is to produce a flow meter that does not require the individual flow components to be separated and measured separately. This goal can be met if a homogenized mixture is produced which can be measured by a standard single phase flow meter. The slotted orifice plate was invented as a flow meter for single phase flows, it is independent upon upstream flow conditions. Slotted orifice plate flow meter's utilization in two-phase flow revealed that it is highly capable of working as a flow conditioner transforming most of the multiphase flow regimes into a fairly uniform mixture. This study measures how the relative homogeneity of an air/water mixture varies downstream of the slotted plate in a horizontal pipe for various upstream conditions including elongated bubble and slug flow regimes using electrical resistance tomography (ERT). According to this study, the optimal location with a maximum homogeneity was determined to be between 1.5 and 2.5 pipe diameters downstream of the slotted orifice plate. This indicates that placing a slotted orifice plate at the obtained distance upstream of another flow meter such as a venturi coupled with a density measuring device like a radiation based densitometer or an electrical impedance device will help in obtaining accurate multiphase flow rate measurement.

Design of mass flow rate measurement system for SST-1 superconducting magnet system

Superconducting Magnet System (SCMS) of Steady State Superconducting Tokamak – 1 (SST-1) is forced-flow cooled by a closed cycle 1.3kW (at 4.5K) class Helium Refrigerator cum Liquefier (HRL) system. An accurate measurement of helium mass flow rate in different coils is required to ensure the uniform cooling of the cold mass in the entire range of operating temperature (300K to 4.5K) and pressure (0.9–0.4MPa). To meet this requirement, indigenously designed and fabricated venturi meters are installed on 27 different coils of SST-1 SCMS. A VME based Data Acquisition System (DAS) has been developed and used to acquire the flow measurement data from different flowmeters. The details of the design of venturi meter, its different measurement and signal conditioning components, the data acquisition system and the mass flow rate calculation method are described in this paper. The mass flow rate measurement data from cryogenic acceptance and SST-1 magnet commissioning experiments are also presented and discussed in this paper.

An Integrated Instrumentation System for Velocity, Concentration and Mass Flow Rate Measurement of Solid Particles Based on Electrostatic and Capacitance Sensors.

The online and continuous measurement of velocity, concentration and mass flow rate of pneumatically conveyed solid particles for the high-efficiency utilization of energy and raw materials has become increasingly significant. In this paper, an integrated instrumentation system for the velocity, concentration and mass flow rate measurement of dense phase pneumatically conveyed solid particles based on electrostatic and capacitance sensorsis developed. The electrostatic sensors are used for particle mean velocity measurement in combination with the cross-correlation technique, while the capacitance sensor with helical surface-plate electrodes, which has relatively homogeneous sensitivity distribution, is employed for the measurement of particle concentration and its capacitance is measured by an electrostatic-immune AC-based circuit. The solid mass flow rate can be further calculated from the measured velocity and concentration. The developed instrumentation system for velocity and concentration measurement is verified and calibrated on a pulley rig and through static experiments, respectively. Finally the system is evaluated with glass beads on a gravity-fed rig. The experimental results demonstrate that the system is capable of the accurate solid mass flow rate measurement, and the relative error is within −3%–8% for glass bead mass flow rates ranging from 0.13 kg/s to 0.9 kg/s.

Drop Measurement System for Biomedical Application

This paper describes the realization of a sensor capable of measuring the volume of a drop in free fall. The sensor realized is made of a simple low-cost red laser and a photodiode and optics to focus the beam on the light sensor. In this way, when the drop is falling down, it is possible to estimate its volume from the signal generated on the photodiode while getting through the laser beam. This system may be very useful together with a drip chamber to have accurate and low-cost volume and flow rate measurements of the infused substances.

Multiphase Flowmeter for Testing Heavy-Oil Wells in Offshore Brazil

Summary In the heavy-oil Atlanta field, well-test operations were planned initially with a multienergy gamma ray/Venturi multiphase flowmeter as a contingency. During the well-test operations, the foaming propensity of the produced oil made it almost impossible to distinguish an interface between liquid and gas in the separator or tank, rendering the standard equipment useless. Only in the second test were some tank measurements available. The measurement principle used in this multiphase flowmeter, however, is not sensitive to foam or emulsion because the meter responds to the atomic-level composition of the different components of the mixture independently of their arrangement, providing accurate flow-rate measurements. Therefore, it became the main flowmetering device for the operator. We detail the behavior of the multiphase flowmeter during the well tests in the Atlanta field and the challenges caused by this highly viscous oil. In the case of standard oils, the measurements are not sensitive to the viscosity value. However, in the case of low Reynolds numbers, the viscosity value can dramatically affect the results. In this case, some solvents were injected during the well test to reduce the liquid viscosity, and we present the consequences for the multiphase flowmeter. Because it was not possible to measure the viscosity directly at the wellsite, we highlight the work flow that was followed to determine the proper viscosity value to use. The viscosity number was validated by comparing the multiphase-flowmeter measurements to the gas/oil ratio measured in the laboratory on downhole samples from the same reservoir, to the water cut measured manually during the operations and to the tank total-liquid-rate measurements. Finally, we present some recommendations on the use of multiphase flowmeters for heavy-oil well tests.

Numerical evaluation of SmCo permanent magnet flowmeter measuring sodium flow in a low flow rate regime using FLUENT/MHD module

One of the several key subsystems in the test facility of Korean sodium-cooled fast reactor is a plugging meter system, which measures the impurities in the sodium using an indirect online technique. To measure the low flow rate, a permanent magnet flowmeter was developed owing to its inherent fast response time, non-invasive characteristic, relatively accurate flow rate measurements, and excellent linearity between the flow rate and flowmeter signal. However, several limitations have been reported in the experimental evaluation of the flowmeter under low flow rate conditions given the measurement capability of the current experimental facility. Thus, the performance of the flowmeter was evaluated numerically using a commercial computational fluid dynamics tool, a FLUENT/MHD module, based on the finite volume method with the help of electromagnetic analysis software, ANSYS MAXWELL. The FLUENT/MHD module was validated by comparing the simulation results with the experimental results. The relative error of the FLUENT simulation was estimated to be approximately 0.24% compared with the experimental results. After the validation process, MHD simulations were conducted to calculate the flowmeter voltage signals versus flow rates, especially in a low flow rate regime, where the linearity between the flow rate and flowmeter signal was carefully analyzed.

J0540106 マイクロ流路を通過する水分子の質量流量の計測

Along with the development of micro- and nano-technologies, gas-surface interaction becomes important due to large surface area-to-volume ratio in micro-scale gas flows. In such flows, the Knudsen number (Kn) is often employed as a parameter of rarefaction of flows. When 0.01<Kn≦0.1, a flow is classified as the slip flow with a finite velocity slip at boundary. In this regime, the mass flow rate increases from the rate in the continuum regime because of the velocity slip. The mass flow rate depends on the combination of molecule and surface. In this study, we measured the mass flow rate of water molecules to investigate the characteristics on gas properties. The constant-volume technique was employed for measuring the mass flow rate through a micro channel. The obtained results suggested that the adsorption of water molecules on the measurement system influenced the accurate measurement of the mass flow rate.

A Lorentz force flow meter for application at blast furnaces: design and calibration

AbstractA reference Lorentz force flow meter (LFF) has been developed to measure molten steel mass flow at the end of the runner of an experimental blast furnace. It works according to the principles of Lorentz force velocimetry [1] in which a static magnetic field interacts with a liquid metal stream. The magnetic field lines are generated by an arrangement of permanent magnets and penetrate the entire cross‐section of the flow generating eddy currents and a total Lorentz force inside the melt. This force is proportional to the mass flow of the liquid metal and owing Newton's third law, there is a counter force of the same magnitude acting on the magnet system which is connected to a load cell. For accurate flow rate measurements, a “dry and wet calibration” of the LFF needs to be performed [2]. (© 2014 Wiley‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

Simulation and experimental verification of a fuel calibration system based on metering cylinder

Simulation and experimental verification of a fuel calibration system based on hydraulic metering cylinder has been carried out in this paper. A novel hydraulic metering cylinder is designed for more accurate flow rate measurement. The calibration workbench with this cylinder is presented and mathematically modeled. Also, the calibration system is numerically simulated in AMESim. The simulation results show that the calibration system can work smoothly. In addition, the impact of given plunger speeds and calibration strokes on the accuracy of the calibration results is experimentally verified. It can be found that stroke of approximate 600mm and a medium given speed are the most effective ways to reduce the measuring error under the experimental condition provided in this paper. Moreover, a calibration error less than 0.5% is achieved in the fuel calibration system.

Research Funded by DOE/RPSEA Advances Ultradeepwater Technology

Technology Update A number of research projects awarded by the Research Partnership to Secure Energy for America (RPSEA), with funding and oversight by the United States Department of Energy’s National Energy Technology Laboratory (NETL), have shown solid potential to advance deepwater and ultradeepwater (UDW) oil and gas development. The DOE/RPSEA projects are among more than 15 to be featured in a session on funding new E&amp;P technologies on 7 May at the Offshore Technology Conference (OTC) in Houston. Chairing the session will be James Pappas, vice president of ultradeepwater at RPSEA. Nine of the technologies developed through this research are discussed herein. One of the projects, highlighted on the cover of the January 2014 issue of JPT, is the Lockheed Martin Marlin autonomous underwater vehicle. This system has the following advantages over remotely operated vehicle (ROV) systems: 3D model generation in hours vs. days; the use of smaller vessels with fewer crew members; no need for umbilical management; realtime change detection, enabling on-site assessment of survey results and structural anomalies; rapid assessment capability of potential environmental damage; and the ability to generate accurate, geo-registered models for structural integrity assessment. Also under consideration is the inclusion of high-resolution visual imaging to enable accurate subsea measurement of flow rate from a blowout or from ocean floor seeps for predrilling site investigations. The project is in its final phase of development and scheduled to be complete by June. Another interesting set of projects deals with metocean issues that affect UDW development. Studies in this area have continued since the early days of UDW research and development within RPSEA. The first efforts studied the US Gulf of Mexico (GOM) loop currents to develop a better hurricane forecasting model, because these relatively warmer currents often increase hurricane intensity. The goal of these projects was to develop a better long-range forecast (of up to 90 days) of hurricane activity in the GOM. The newer models with higher resolution potentially could better describe the density of the spiral rain bands caused by higher wind velocities farther from the center of the storm. The spacing of these bands appears to have a greater influence on the extent of damage sustained by an offshore vessel than hurricane classification or size, as the spacing more directly affects seawater wave height.

Experimental and numerical investigation of hydro power generator ventilation

Improvements in ventilation and cooling offer means to run hydro power generators at higher power output and at varying operating conditions. The electromagnetic, frictional and windage losses generate heat. The heat is removed by an air flow that is driven by fans and/or the rotor itself. The air flow goes through ventilation channels in the stator, to limit the electrical insulation temperatures. The temperature should be kept limited and uniform in both time and space, avoiding thermal stresses and hot-spots. For that purpose it is important that the flow of cooling air is distributed uniformly, and that flow separation and recirculation are minimized. Improvements of the air flow properties also lead to an improvement of the overall efficiency of the machine. A significant part of the windage losses occurs at the entrance of the stator ventilation channels, where the air flow turns abruptly from tangential to radial. The present work focuses exclusively on the air flow inside a generator model, and in particular on the flow inside the stator channels. The generator model design of the present work is based on a real generator that was previously studied. The model is manufactured taking into consideration the needs of both the experimental and numerical methodologies. Computational Fluid Dynamics (CFD) results have been used in the process of designing the experimental setup. The rotor and stator are manufactured using rapid-prototyping and plexi-glass, yielding a high geometrical accuracy, and optical experimental access. A special inlet section is designed for accurate air flow rate and inlet velocity profile measurements. The experimental measurements include Particle Image Velocimetry (PIV) and total pressure measurements inside the generator. The CFD simulations are performed based on the OpenFOAM CFD toolbox, and the steady-state frozen rotor approach. Specific studies are performed, on the effect of adding "pick-up" to spacers, and the effects of the inlet fan blades on the flow rate through the model. The CFD results capture the experimental flow details to a reasonable level of accuracy.