Differential Pressure Meter Research Articles

Devices and methods for wet gas flow metering: A comprehensive review

Wet gas is commonly encountered in various industries, including energy, chemical, and electric power sectors. For example, natural gas extracted from production often contains small amounts of liquid, such as water and hydrocarbon condensates, which classifies it as wet gas. The presence of liquid within the gas poses challenges for accurate flow measurement. To improve the performances of wet gas flow metering methods, significant research and development efforts have been invested into the wet gas flow metering technologies due to their vital importance in the production, transfer, and trade benefits.This paper presents a comprehensive overview of the recent development of wet gas flow metering. Firstly, a comprehensive discussion of the Lockhart-Martinelli parameter (Xlm) and its relation to the gas void fraction (αg) is presented, which was mostly overlooked in previous wet gas research work. The occurrence of various flow patterns in wet gas conditions at different orientations (horizontal and vertical) was explored. Following an investigation of pressure impact on the wet gas flow patterns and development of the wet gas regions, a different test matrix for further research work was suggested. After a novel classification of wet gas measurement methods, the paper offers a detailed comparison of differential pressure (DP) meters including Venturi, Cone meter, and orifice meters, by considering both liquid and gas flow rate measurements. Secondly, the paper discusses and compares vortex flow meters, Coriolis and ultrasonic meters in comparison to DP meters. Notable phase fraction meters are also examined and compared to one another. Thirdly, the paper reviewed the concept of existing and potential hybrid wet gas meters, conducting a detailed discussion and comparison with commercial solutions by evaluating their ranges and accuracies. This assessment provides valuable insights into the capabilities of these hybrid meters, highlighting their potential to enhance the measurement of wet gas flow rates.

Gas-liquid two-phase flow rates measurement using physics-guided deep learning

Machine learning has been widely used in the gas-liquid two-phase flow field. However, data-driven machine learning methods are often considered black-box methods which may lead to insufficient interpretation and extrapolation abilities. Combining machine learning and physical principles is a promising method to improve the generalization abilities and interpretation of the deep neural network model, which is still a challenge in gas-liquid two-phase flowrates measurement. In this work, we propose a physics-guided deep learning model for gas-liquid two-phase flow rate measurement through the differential pressure meter. The simplified physical constraint term of gas-liquid two-phase flow is established based on the momentum equation and continuity equation of gas-liquid two-phase flow, and then, the physical constraint term is added to the loss function of the deep neural network. Consequently, the predictions of the model not only satisfy the target values but also conform to the physical term. The performance of the physics-guided neural network (PGNN) is tested and compared with an artificial neural network (ANN) model that is trained without the physical constraint term. Results show that the gas and liquid flow rates could be measured simultaneously with satisfactory accuracy using the proposed PGNN model, more importantly, the model also performs well on a wider range of testing conditions (Gas Volume Fraction, GVF>95%). It indicates that this method is possible to improve the generalization and interpretation of the purely data-driven neural network model.

A Correction Method for Wet Gas Flow Metering Using a Standard Orifice and Slotted Orifices.

Flow measurements that utilize differential pressure meters are commonly applied in industry. In such conditions, gas flow is often accompanied by liquid condensation. For this reason, errors occur in the metering process that can be attributed to the fluctuations in continuous phase parameters in the flow. Furthermore, the occurrence of a dispersed phase results in flow disturbance and dynamic pressure pulsations. For the above reasons, new methods and tools are sought with the purpose of performing measurements of gas-liquid flows providing measurement results that can be considered as fairly accurate in the cases when flow involves a liquid phase form. The paper reports the results of a study involving measurement of wet gas flow using differential pressure flowmeters. The experiments were conducted for three constant mass air flow rates equal to 0.06, 0.078 and 0.086 kg/s. After stabilization of the air flow rates, water was fed into the pipe with flow rates in the range from 0.01 to 0.16 kg/s. The research involved a standard orifice and three types of slotted orifices with various slot arrangements and geometries. The analysis focused on the effect of orifice geometry on the flow metering results. On the basis of the results, it was found that the slotted orifice generates smaller differential pressure values compared to the standard orifice. The water mass fraction in the gas leads to overestimated results of measurements across the flowmeter. Regardless of the type of the orifice, is necessary to undertake a correction of the results. The paper proposes a method of gas mass flow correction. The results were compared with the common over-reading correction models available in the literature.

Wet gas pressure drop across orifice plate in horizontal pipes in the region of flow pattern transition

As a basis for measuring the mass flow rate of wet gas using differential pressure meters, predicting the pressure drop of a wet gas flowing through orifice plates is important; however, this has not yet been solved satisfactorily, although many studies have reported on that subject. In this study, the pressure drop of wet gas across sharp-edged orifice plates was experimentally investigated in the region of flow pattern transition using air and water as the two phases, and the prediction performance of the available pressure drop models was compared based on the experimental data. The results show that the homogenous flow models overestimate the pressure drop, whereas those models based on the separated flow model often present underestimations. The models reported for wet gas are also incapable of predicting the pressure drop in this region with acceptable accuracy. Through an analysis of the prediction deviations, it is found that the Froude number of the liquid phase has a significant influence on the pressure drop of the wet gas, besides the Froude number of the gas phase. Then, three new correlations that are based on the homogeneous flow, Chisholm model, and Murdock model, respectively, were proposed based on the experimental result.

Dust Mask with a Pressure Drop Measuring Device

Introduction. Respiratory diseases are the leaders among the scope of occupational diseases. This result from air pollution in working area by hazardous air disperse particles, gases, vapours or using individual respiratory protective devices (IRPD), which do not allow control of respiratory-protection period and thus increase the risk of occupational diseases. Theoretical analysis of protective efficiency of dust respirators and research purpose statement. The use of dust respirators is associated with the following operational problems: protection factor is significantly reduced during the work activities, so it is needed to replace filtering components very often; non filtrated air leaks through the obturation line of half mask as a result of no uniform distribution of pressure; control of respiratory-protection period of filters is impossible. Design of dust respirator with differential pressure meter. The solution of the problem is suggested as change of dust respirator by adding of differential pressure meter consisting of pressure control sensor, unit of control and information processing, appliance for information recording and storage, signal unit, and power source. The suggested design of dust respirator enables improvement of protection properties and reduction of air leakage through the gaps between obturation line and worker’s face occurring during the work activities because of head harness weakening or exceeding of resistance of filters performance and determining of critical state of their exploitation.Algorithm development for pressure meter operation of dust respirator. Pressure sensor is placed under the respirator mask. Its output is connected to input of unit of control and information processing, which transmits data to signal unit and appliance for information recording and storage. After the processing the information is compared to settings and control signals are transmitted to turn on light and sound indicators. Moreover, the information is recorded to be stored in appliance for information recording and storage. Alert sounds of variable duration and cycles depending on pressure under the mask during the air inhalation are easy-to-see in darkness and are likely to attract worker’s attention. Experimental studies of workability of dust respirator with pressure meter. Laboratory workability check of pressure meter of respirator has demonstrated similarity of measuring results of pressure difference in filters in case of dusting. The periods were determined for pressure meter signals the need in filter change and in case of half mask sliding during the work activities resulting in new gaps. Discussion. The main feature of the developed dust respirator in comparison with the common ones in sale is permanent monitoring of pressure difference under the mask. It enables determining of actual protection period of filters and provides the right place of mask on face as being controlled by the maintenance of minimum value of air exhaustion under the mask. The level of worker protection during work activities wearing IRPD is determined with respect to the indicators. Thus, addition of pressure meter into IRPD enables improvement of workers’ protection from dust during their work activities. Conclusions. The design of pressure meter for dust respirator was developed. The algorithm of meter operation was proposed; it enables control of change of breath pressure difference using increase of filters resistance resulting from dust deposits on their surface, improper seal of respirator half mask and worker’s face during the work activities.

A new correlation of wet gas flow for low pressure with a vertically mounted Venturi meter

Wet gas metering has become an increasingly important technique for many industries. However, the over-reading phenomenon reduces the accuracy of Differential Pressure meters. This research fills the vacancy of correlations and presents a new correlation for low pressure between 0.82 and 1.52 MPa with a vertically mounted Venturi meter to calculate the over-reading coefficient accurately. Based on the correlational analysis, the over-reading coefficient is a function of the Lockhart-Martinelli parameter, density ratio, and gas Froude number. The constant coefficients in this correlation are obtained by nonlinear regression. Effect of low gas velocity with gas Froude number under 1.5 is taken into consideration as well. The average relative error is 1.9% and the root mean square error is 3.0%. Furthermore, a new method to calculate the over-reading coefficient for industrial applications is put forward due to the difficulties of online measurements of the Lockhart-Martinelli parameter which is substituted with the void fraction. The void fraction is calculated by an empirical correlation using quality and an approximate algorithm is utilized to obtain gas Froude number. For this new method, the average relative error is 2.3% and the root mean square error is 3.7%. This quality-based method will be helpful to resolve the limited applicability of gamma-ray attenuation for wet gas flow metering in industry regarding vertical low pressure conditions.

Quadrature Demodulation 을 적용한 초음파 유량계 시스템 개발

There are various methods for measuring flow rate. In measuring the flow rate, types of flow meters include electronic turbine, ultrasonic wave, vortex, and differential pressure meters. Typically, turbine flow meters and ultrasonic flow meters are often used to measure liquid flow rates. Because of a disadvantage whereby the turbine type requires cutting the tubing, this paper presents an ultrasonic flow meter. In this paper, the flow rate is measured using the difference in the time of flight (TOF) for ultrasonic waves. In order to improve TOF accuracy while implementing a simple system at a low cost, TOF was measured using the quadrature demodulation and phase difference of the received ultrasonic signal. Experiment results are compared with two commercial products: a turbine flow meter and an ultrasonic flow meter. The results show that accuracy with the proposed ultrasonic flow meter is similar to the two commercial products.

Dynamics of feed water flow rate control system with low- noise regulator

We present the results of modeling a feed water control system. The system contains two regulatory devices the feed valve to control the flow rate, with electrohydraulic control, and the throttle valve to maintain constant pressure differential on the feed valve, with hydromechanical control. The valves have perforated flow parts to reduce hydrodynamic noise and vibration, which necessitates checking the dynamical characteristics of the system. The model was developed on the basis of equations describing the electrohydraulic converter dynamics, a differential pressure meter, a servo drive and flow parts with the use of Matlab Simulink. The modeling of dynamical processes caused by various disturbance inputs and control actions showed the compliance of the system with the requirements imposed on it.

Comparison of high temperature and high Reynolds number water flows between PTB and NMIJ

Bi-comparison for high temperature and high Reynolds number water flows was performed between Physikalische-Technische Bundesanstalt (PTB) and National Metrology Institute of Japan (NMIJ) using differential pressure meters. The flowrate range considered herein was from 250m3/h to 740m3/h and the temperature range was from 20°C to 80°C. The Reynolds number based on the pipe diameter ranges from 4.4×105 to 3.6×106. The expanded uncertainty of volumetric flowrate with a coverage factor k=2 is 0.040% for PTB and 0.070% for NMIJ. The differential pressure meters as the transfer meter were a throat-tapped flow nozzle and an orifice. The results for both flow meters were in good agreement between the two labs. The difference in the average discharge coefficient at the same Reynolds number ranged from −0.05% to 0.03% for the flow nozzle and from −0.01% to 0.05% for the orifice. The results of the comparison indicate a high level of consistency between PTB and NMIJ for high temperature and high Reynolds number water flows.

Error analysis of gas and liquid flow rates metering method based on differential pressure in wet gas

Online measurement of gas and liquid flow rates in wet gas is of great significance in industry. When the differential pressure meter is used to measure the gas and liquid flow rates, an over-reading correlation is needed to correct the liquid-induced overestimation of the gas flow rate and an auxiliary correlation is needed to obtain the liquid fraction or flow rate. With the two correlations incorporated, the gas and liquid flow rates can be calculated. In the present study, error analysis of this metering method is conducted. The results demonstrate that metering methods based on differential pressure exhibit similar error pattern, i.e., the prediction error of gas phase is small while that of the liquid phase is large. This phenomenon can be interpreted by error propagation and the underlying physics is that the two-phase differential pressure is mainly dependent on the gas phase but insensitive to the liquid phase. It is found that both the mean value and the fluctuation of the differential pressure signals are able to reflect flow rate changes of wet gas flow. However, metering methods based on the differential pressure fluctuation present larger prediction errors than that based on the differential pressure mean value. The reason is that the differential pressure fluctuation has much poorer repeatability compared with the differential pressure mean value.

Effects of Pipe Wall Offsets on Differential Pressure Meter Accuracy

Accurate flow measurement is essential for the management of any type of fluid system. This research investigated the effect on accuracy that five types of 12‐in. differential‐pressure flow meters have as a result of being installed in pipelines of differing inside diameter. The types of meters chosen for this research were the classical Venturi meter, Halmi Venturi Tube, wedge meter, V‐cone meter, and the X‐meter. Each meter was tested for accuracy with10 pipe wall offsets varying from a 0.125‐in. sudden contraction to a 0.937‐in. sudden expansion of the pipe radius. The meters' reading during each test series was compared with the meters' reading with no pipe wall offset at the same Reynolds number. This research demonstrated that for accurate flow measurement, most flow meters require that the inside diameter of the piping be the same as the inside diameter of the meter.

Application of Microfluidic Device for Lactic Biosensor

In this paper, the RuO2 sensing film is fabricated by the sputtering system, and the miniature reference electrode is fabricated by the screen printed technique for integrating the RuO2 thin film in the array flexible sensor. Furthermore, the computer numerical control technique is used to fabricate the stainless model of the fluidic channel, and polydimethylsiloxane is used as the material of the fluidic channel. Finally, the array flexible sensor is integrated fluidic channel to form the potentiometric biosensor of the fluidic. The property of the fluidic channel is analyzed by differential pressure meter to measure the pressure drop and discuss the effect of related factors. In this paper, the RuO2 based pH sensor can obtain a higher sensing value at 61.3 mV/pH with super-Nernstian response. Besides, due to silver's excellent stability and conductivity, the miniature reference electrode is fabricated by screen printed technique to fix silver at the polyethylene terephthalate substrate. The sensitivities of the sensor of 61.31, 59.65, and 56.45 mV/pH with flow rates of 10, 20, and 30 ml/min, respectively, are obtained. The experimental result demonstrates that the potentiometric biosensor can be applied to detect the fluidic concentration.

Insight into pressure drop dependent efficiencies of dry powder inhalers

PurposeThe purpose of this study was to assess the effectiveness of three commercial capsule-based dry powder passive inhalers [Rotahaler® (RH), Monodose Inhaler® (MI) and Handihaler® (HH)] in de-agglomerating salbutamol sulphate (SS) and micronized lactose (LH300) powders and their sensitivity to air flow rate changes and air flow resistance. MethodsAerosolisation was assessed in real-time using a laser diffraction method: this approach was possible as only single-component formulations were tested. Volume percent of the aerosolised particles with diameter less than 5.4μm at air flow rates from 30 to 180lmin−1 was obtained with the RH, MI and HH and provided a parameter, relative de-agglomeration (RD), as a measure of de-agglomeration. The pressure drops across the device at various flow rates were obtained from a differential pressure meter. ResultsThe relationship between RD of SS and LH300 and air flow rate appeared substantially different between the devices. It was surprisingly found that in some cases RD dropped at the highest air flows: this indicates a device specific maxima in RD occurs, and this may in part be attributed to changes in capsule motion. It is proposed that this relationship between RD and pressure drop provides a patient focussed simple way to assess RD performance. This assessment indicated that MI was the most efficient relative de-agglomerator at lower pressure drops, while HH increases its effectiveness at higher pressure drops. ConclusionThe approach of measuring RD as a function of pressure drop revealed instructive variations in the aerosolisation performances of different devices. This new approach helps compare device performances with different powders, and hence improve optimisation and consistency of performance.

Gas-Well Liquid Loading Probed With Advanced Instrumentation

Summary Drop size, liquid holdup, and pressure drop have been measured simultaneously in real time. This experiment was carried out with air/water to establish annular two-phase flow on a 0.019-m-internal-diameter vertical pipe (7-m-long multiphase-flow facility). Drop concentration, distribution, and sizes in the core flow were measured using Spraytec, a light-diffraction-based instrumentation. Liquid holdup was logged with pairs of flush-mounted ring-conductance probes at various positions within the test section. Pressure drop was monitored using a differential-pressure meter mounted between two pressure taps separated by a distance of 1.5 m. Subtle changes were observed in the characteristic drop diameters around gas superficial velocities of 21 and 30 m/s following progressive, systematic increase in gas and liquid superficial velocities. The gas superficial velocities at which these changes were observed have been linked with transition boundaries to cocurrent and mist annular flows, respectively. Corresponding similar pseudochanges, fingerprinted in the liquid-holdup and pressure-drop data at these transition boundaries, in addition to film and drop-flow reversals captured on video, make the evidence more compelling. Applicability of core-flow dynamic data to explain various physical processes associated with gas-well liquid loading has been demonstrated.

0814 安定温度成層化による管内流の圧力損失低減(OS8 流れの抵抗低減,オーガナイズドセッション)

This paper investigated turbulent suppression caused by the thermal stratification in horizontal pipe.The present study finds that when the pipe flow becomes stratified,the mixing in vertical direction is suppressed and pressure drop decrease.Therefore,we investigated the tendency to decrease the pressure loss of pipe flow by changing the flow rate of upper-hot flow in a pipe.Experiments were performed using the differential pressure meter to measure the pressure drop.The experimental results show that the reduction of pressure drop is more remarkable in the stratified condition that velocity difference between upper and lower flow is high.

High GVF and low pressure gas–liquid two-phase flow measurement based on dual-cone flowmeter

Parameter measurement of gas–liquid two-phase flows with a high gas volume fraction (GVF) has received great attention in the research field of multiphase flow. The cone meter, as a new proposed differential pressure (DP) meter, is increasingly being applied in flowrate measurement of gas–liquid two-phase flow. A dual-parameter measurement method of gas–liquid two-phase flow based on a dual-cone meter is proposed. The two-phase flow is investigated in a horizontal pipeline with high GVF and low pressure, and exists in the form of annular flow. By adding a second cone meter, both gas mass fraction (GMF) and mass flowrate are measured. The pressure drop performances of five different sized cones have been discussed to make a cooperating cone selection and efficiently position the dual-cone in the pipe. Dual-cone flowmeter experiments of 0.45 and 0.65 equivalent diameter ratio combination, and 0.65 and 0.85 equivalent diameter ratio combination are respectively carried out to analyze the linearity of two-phase flow multiplier with Lockhart–Martinelli parameter and obtain the dual-parameter measurement results. The relative experiment error of GMF, gas mass flowrate and total mass flowrate are respectively within ±7%, ±5% and ±10%. The relative error of the liquid phase is within ±10% when the liquid mass fraction is beyond 40%. The experimental results show that it is efficient to utilize this dual-cone method for high GVF and low pressure gas–liquid two-phase flow measurement.

Modification to mass flow rate correlation in oil–water two-phase flow by a V-cone flow meter in consideration of the oil–water viscosity ratio

Oil–water two-phase flow widely exists and its measurement is of significance in oil well logging, oil transportations, etc. One of the techniques in common use in oil–water two-phase flow rate measurement is the differential pressure (DP) meters combining a theoretical model connecting the mass flow rate of the mixture with the differential pressures generated by the throttling element installed inside the pipeline. Though a number of publications focus on DP meters in measuring gas–water two-phase flows or wet gas, the existing models are still not very compatible in oil–water two-phase flow. In this work, a series of oil–water two-phase flow experiments were conducted in a horizontal pipe of 50 mm diameter and the flow rate was measured by a V-cone meter with a diameter ratio of 0.65. Available correlations of DP meters developed from gas–water flow are studied and compared with the measured data from the V-cone meter. A modified correlation is proposed based on the influence of viscosity of oil upon the differential pressure model and three-dimensional computerized fluid dynamic (CFD) simulations. The results have shown that the proposed method achieves better accuracy in oil–water two-phase flow rate measurement than other DP correlations, and it can be extended to other oil–water flow conditions by adjusting the tuning factor.

Extrapolation and Curve-Fitting of Calibration Data for Differential Pressure Flow Meters

Performance test codes require primary mass-flow accuracies that in many applications require laboratory quality calibration of differential pressure meters. It is also true that many performance tests are conducted at Reynolds numbers and flows well above the laboratories' capacities, and sound extrapolation methods had to be developed. Statistical curve fits and regression analyses by themselves, absent fluid-dynamic foundations, are not valid procedures for extrapolation. The ASME PTC 19.5-2004 discharge coefficient equations reproduced in this paper for nozzles, orifices, and venturis are suitable for use whenever calibration data are to be applied in a flow measurement and/or extrapolated to higher Reynolds numbers as necessary. The equations may also be used for uncalibrated differential pressure meters by using nominal values. It is necessary to note that the metering runs must be manufactured with dimensions, tolerances, smoothness, etc., and installed in strict accordance with ASME PTC 19.5 for these equations to be valid. Note that for compressible flow, the value of the expansion factor term in the PTC 19.5 equation must be the one corresponding to the published PTC 19.5 equation.

Effect of second phase on single phase flow meters in steam quality measurement

This paper presents results from an investigation of the two phase flow, especially liquid ingas phase, in most mainly used flow meter in steam industry namely differential pressuremeter is investigated. As in general, a flowmeter is designed and employed to measure flowrate of single phase fluid. There are many types of meter available in the market characterizeby their working principles, installed conditions and measured fluid. All meters representtheir accuracies under the single phase flow condition. However, when they are working inunusual conditions especially under multiphase flow, most meters lose their accuraciessignificantly even there is small amount of second phase introduced into the system. Tounderstand the deteriorated performance of the meter under two phase flow, additional studyon the effect the second phase on the meter is required.The laboratory experiment is set up to simulate the wet steam by flowing compressed airin the 2 inch pipe. Water droplet is generated by pressurized water flowing through a nozzleand then spayed into the system in range of 25% maximum by mass fraction. The signal fromeach flowmeter is collected by digital computer and analyzed using FFT and power spectrumdensity. The results show that the presence of the second phase in the system causes highfrequency fluctuation and causes significant error on meter reading. Flow manufacturersalways add low-pass filter circuit to remove this high frequency signal, however, this papershows that the high frequency signal in specific region is useful as it can be use to estimatedthe percentage of the second phase in the main phase system.

Horizontally installed cone differential pressure meter wet gas flow performance

Differential pressure (DP) meters which utilise a cone as the system’s primary element are increasingly being used to measure wet natural gas flows (i.e. mixtures of natural gas, light hydrocarbon liquids and water). It is therefore important to understand this meter’s response to wet natural gas flows. Research into the wet gas response of the horizontally installed cone DP meter is discussed in this paper. Consideration is given to the significant influence of the liquid properties on wet gas flow patterns and the corresponding influence of the flow pattern on the cone DP meter’s liquid phase induced gas flow rate prediction error. A wet natural gas flow correlation for 4 in. 0.75 beta ratio cone DP meters with natural gas, hydrocarbon liquid and water flow has been developed from multiple data sets from three different wet gas flow test facilities. This corrects the liquid induced gas flow rate prediction error of a wet gas flow up to a Lockhart–Martinelli parameter of 0.3, for a known liquid flow rate of any hydrocarbon liquid/water ratio, to ±4% at a 95% confidence level.