Leak Detection in Liquid Subsea Flowlines With no Recorded Feed Rate

1999 ◽  
Vol 121 (3) ◽  
pp. 161-166 ◽  
Author(s):  
J. M. Dinis ◽  
A. K. Wojtanowicz ◽  
S. L. Scott
Keyword(s):  
Flow Rate ◽  
Deep Sea ◽  
Measurement Errors ◽  
Pressure Fluctuations ◽  
Resistance Coefficient ◽  
Production Data ◽  
Mean Values ◽  
Wellhead Pressure ◽  
Inlet Flow Rate ◽  
Statistical Noise

This paper presents a statistical method to detect leaks in subsea liquid flowlines when the inlet flow rate measurements are unavailable and conventional mass balance techniques cannot be used. Presently, the only method used in these situations is to “predict” the inlet rate from a steady-state reservoir/wellbore model for use in a transient pipeline simulator. The purpose of this work was to examine the utility of a pressure loss model which requires only routine production data. This technique is derived from the statistical theory of estimation and testing, and treats fluctuations due to turbulence, transients, and measurement errors as statistical noise. This method compares two mean values of the pipeline resistance coefficient, R; the new updated value representing the potential leak and the old value being R without leak. Precision of the new method was demonstrated using the 9460-ft long, (3.64 in. i.d.) flowloop at LSU, with flowrates up to 10,000 bbl/day of water, and pressures up to 2400 psi. The leak was simulated by an orifice which discharged the water from the flowline into a shut-in-well. An environmental (wellhead) pressure up to 2200 psi was applied to simulate hydrostatic pressure in the deep-sea environment. The results presented in this paper show how detection of small leaks relates to the number of R measurements, leak position, and statistical noise resulting from flow rate-pressure fluctuations, transients, and measurement uncertainties.

Pressure and Flow Rate Fluctuations in Single- and Two-Blade Pumps

2020 ◽  
Vol 143 (1) ◽  
Author(s):  
Andreas Pesch ◽  
Steffen Melzer ◽  
Stephan Schepeler ◽  
Tobias Kalkkuhl ◽  
Romuald Skoda
Keyword(s):  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
Three Dimensional ◽  
Electromagnetic Flowmeter ◽  
Flow Region ◽  
Mean Values ◽  
Wall Pressure Fluctuations ◽  
Simulation Results ◽  
Blade Pump

Abstract A comparative study on the highly unsteady flow field in single- and two-blade pumps is performed. Stationary pump characteristics, as well as pressure and flow rate fluctuations, are presented. Wall pressure fluctuations were measured in the suction and pressure pipe as well as at several locations within the volute casing by piezoresistive transducers. Flow rate fluctuations were evaluated by a recently presented measurement system based on an electromagnetic flowmeter (Melzer et al. 2020, “A System for Time-Fluctuating Flow Rate Measurements in a Single-Blade Pump Circuit,” Flow Meas. Instrum., 71, p. 101675). Measurements were accompanied by three-dimensional (3D) flow simulations with the open-source cfd software foam-extend. A thorough grid study and validation of the simulation were performed. By a complementary analysis of measurement and simulation results, distinctive differences between both pump types were observed, e.g., flow rate and pressure fluctuation magnitudes are significantly higher in the single-blade pump. In relation to the respective mean values, flow rate fluctuation magnitudes are one order lower than pressure fluctuation magnitudes for both pumps. For the two-blade pump, fluctuations attenuate toward overload irrespective of the particular pump circuit, while they rise for the single-blade pump. 3D simulation results yield detailed insight into the spatially and temporally resolved impeller–volute interaction and reveal that the single-blade impeller pushes a high-pressure flow region forward in a way as a positive displacement pump, resulting in an inherently fluctuating velocity and pressure distribution within the volute.

scholarly journals Investigation of the transport characteristics of Pb(II) in sand-bone char columns

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110236
Author(s):  
Gang Li ◽  
Jinli Zhang ◽  
Jia Liu ◽  
Tao Luo ◽  
Yu Xi
Keyword(s):  
Adsorption Capacity ◽  
Flow Rate ◽  
Dose Response ◽  
Construction Materials ◽  
Column Height ◽  
Maximum Adsorption Capacity ◽  
Complexation Reaction ◽  
Bone Char ◽  
Inlet Flow ◽  
Inlet Flow Rate

Pb(II) leakage from batteries, dyes, construction materials, and gasoline threaten human health and environmental safety, and suitable adsorption materials are vitally important for Pb(II) removal. Bone char is an outstanding adsorbent material for water treatment, and the effectiveness in Pb(II) removing need to be verified. In this paper, the transport characteristics of Pb(II) in columns filled with a sand and bone char mixture were studied at the laboratory scale, and the influences of the initial concentration, column height, inlet flow rate, and competing ion Cu(II) on Pb(II) adsorption and transport were analyzed. The Thomas and Dose-Response models were used to predict the test results, and the mechanisms of Pb(II) adsorption on bone char were investigated. The results showed that the adsorption capacity of the bone char increased with increasing column height and decreased with increasing initial Pb(II) concentration, flow rate, and Cu(II) concentration. The maximum adsorption capacity reached 38.466 mg/g and the saturation rate was 95.8% at an initial Pb(II) concentration of 200 mg/L, inlet flow rate of 4 mL/min, and column height of 30 cm. In the competitive binary system, the higher the Cu(II) concentration was, the greater the decreases in the breakthrough and termination times, and the faster the decrease in the Pb(II) adsorption capacity of the bone char. The predicted results of the Dose-Response model agreed well with the experimental results and were significantly better than those of the Thomas model. The main mechanisms of Pb(II) adsorption on bone char include a surface complexation reaction and the decomposition-replacement-precipitation of calcium hydroxyapatite (CaHA). Based on selectivity, sensitivity, and cost analyses, it can be concluded that bone char is a potential adsorbent for Pb(II)-containing wastewater treatment.

scholarly journals Quantitative Monitoring of Dynamic Blood Flows Using Coflowing Laminar Streams in a Sensorless Approach

2021 ◽  
Vol 11 (16) ◽  
pp. 7260
Author(s):  
Yang Jun Kang
Keyword(s):  
Blood Flow ◽  
Flow Rate ◽  
Blood Viscosity ◽  
Measurement Errors ◽  
Present Method ◽  
Test Fluid ◽  
Constant Flow Rate ◽  
Rbc Aggregation ◽  
Sinusoidal Flow ◽  
Analytical Expressions

Determination of blood viscosity requires consistent measurement of blood flow rates, which leads to measurement errors and presents several issues when there are continuous changes in hematocrit changes. Instead of blood viscosity, a coflowing channel as a pressure sensor is adopted to quantify the dynamic flow of blood. Information on blood (i.e., hematocrit, flow rate, and viscosity) is not provided in advance. Using a discrete circuit model for the coflowing streams, the analytical expressions for four properties (i.e., pressure, shear stress, and two types of work) are then derived to quantify the flow of the test fluid. The analytical expressions are validated through numerical simulations. To demonstrate the method, the four properties are obtained using the present method by varying the flow patterns (i.e., constant flow rate or sinusoidal flow rate) as well as test fluids (i.e., glycerin solutions and blood). Thereafter, the present method is applied to quantify the dynamic flows of RBC aggregation-enhanced blood with a peristaltic pump, where any information regarding the blood is not specific. The experimental results indicate that the present method can quantify dynamic blood flow consistently, where hematocrit changes continuously over time.

scholarly journals Large Eddy Simulation of Periodic Transient Pressure Fluctuation in a Centrifugal Pump Impeller at Low Flow Rate

Symmetry ◽  
2021 ◽  
Vol 13 (2) ◽  
pp. 311
Author(s):  
Renfei Kuang ◽  
Xiaoping Chen ◽  
Zhiming Zhang ◽  
Zuchao Zhu ◽  
Yu Li
Keyword(s):  
Large Eddy Simulation ◽  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Low Frequency ◽  
Pump Impeller ◽  
Eddy Simulation ◽  
Inlet Flow Rate ◽  
Large Eddy ◽  
Centrifugal Pump Impeller

This paper presents a large eddy simulation of a centrifugal pump impeller during a transient condition. The flow rate is sinusoidal and oscillates between 0.25Qd (Qd indicates design load) and 0.75Qd when the rotating speed is maintained. Research shows that in one period, the inlet flow rate will twice reach 0.5Qd, and among the impeller of one moment is a stall state, but the other is a non-stall state. In the process of flow development, the evolution of low-frequency pressure fluctuation shows an obviously sinusoidal form, whose frequency is insensitive to the monitoring position and equals to that of the flow rate. However, inside the impeller, the phase and amplitude in the stall passages lag behind more and are stronger than that in the non-stall passages. Meanwhile, the strongest region of the high-frequency pressure fluctuation appears in the stall passages at the transient rising stage. The second dominant frequency in stall passages is 2.5 times to that in non-stall passages. In addition, similar to the pressure fluctuation, the evolution of the low-frequency head shows a sinusoidal form, whose phase is lagging behind that by one-third of a period in the inlet flow rate.

scholarly journals Effect of Air Injection on the Internal Flow Characteristics in the Draft Tube of a Francis Turbine Model

Processes ◽  
2021 ◽  
Vol 9 (7) ◽  
pp. 1182
Author(s):  
Seung-Jun Kim ◽  
Yong Cho ◽  
Jin-Hyuk Kim
Keyword(s):  
Flow Rate ◽  
Draft Tube ◽  
Pressure Fluctuations ◽  
Flow Characteristics ◽  
Internal Flow ◽  
Air Injection ◽  
Low Flow ◽  
Francis Turbine ◽  
Navier Stokes ◽  
Vortex Rope

Under low flow-rate conditions, a Francis turbine exhibits precession of a vortex rope with pressure fluctuations in the draft tube. These undesirable flow phenomena can lead to deterioration of the turbine performance as manifested by torque and power output fluctuations. In order to suppress the rope with precession and a swirl component in the tube, the use of anti-swirl fins was investigated in a previous study. However, vortex rope generation still occurred near the cone of the tube. In this study, unsteady-state Reynolds-averaged Navier–Stokes analyses were conducted with a scale-adaptive simulation shear stress transport turbulence model. This model was used to observe the effects of the injection in the draft tube on the unsteady internal flow and pressure phenomena considering both active and passive suppression methods. The air injection affected the generation and suppression of the vortex rope and swirl component depending on the flow rate of the air. In addition, an injection level of 0.5%Q led to a reduction in the maximum unsteady pressure characteristics.

Simulation on Linear-Motor-Driven Water Hydraulic Reciprocating Plunger Pump

2013 ◽  
Vol 842 ◽  
pp. 530-535 ◽  
Author(s):  
Zeng Meng Zhang ◽  
Yong Jun Gong ◽  
Jiao Yi Hou ◽  
Han Peng Wu
Keyword(s):  
Flow Rate ◽  
Deep Sea ◽  
High Efficiency ◽  
Control Method ◽  
Sea Water ◽  
Linear Motor ◽  
Low Flow ◽  
Flow Pulsation ◽  
Plunger Pump ◽  
Water Hydraulic

The water hydraulic reciprocating plunger pump driven by linear motor is suitable to deep sea application with high efficiency and variable control. Aiming to study the principle structure and working characteristics of the pump, two patterns of valve and piston distribution were designed. And the control method and the performance were analyzed by simulation based on the AMESim model. The results show that the pressure and flow pulsation of piston type pump are much smaller than the valve type, even though the piston type is large in scale and works at low flow rate. Compared with a valve distribution tri-linear-motor reciprocating plunger pump (VDTLMP), as the flow rate of the piston distribution double linear motor reciprocating plunger pump (PDDLMP) is decreased from 36.7 L/min to 21.2 L/min theoretically, the pressure pulsation amplitude is decreased from 46% to 2%, and the flow pulsation rate is also decreased from 0.266 to 0.007. These results contribute to the research on deep-sea water hydraulic power pack and direct drive pump with high efficiency and energy conservation.

Research on the Removal Results of Hydrogen Sulfide of the Treatment of Coal Gasification Wastewater Biogas in the Anaerobic Biotrickling Filter

2012 ◽  
Vol 610-613 ◽  
pp. 2000-2005
Author(s):  
Chun Yan Xu ◽  
Hong Jun Han
Keyword(s):  
Hydrogen Sulfide ◽  
Removal Efficiency ◽  
Flow Rate ◽  
Retention Time ◽  
Operating Parameters ◽  
Inlet Flow ◽  
H2s Removal ◽  
Outlet Concentration ◽  
Volume Load ◽  
Inlet Flow Rate

The uncertainty of operating parameters hinders the practical application of the biological desulfurization. To solve this problem, this study which was conducted in room temperature, pH around seven conditions, investigated the effects of the operating parameters on the hydrogen sulfide (H2S) removal performance in the biotrickling filter, including inlet H2S concentration, inlet flow rate or gas retention time, inlet volume load and circulating liquid spraying flux. The results showed that, the inlet H2S concentration should be controlled within 800mg/m3, 650mg/m3, 400mg/m3, 300mg/m3 respectively while the inlet flow rate was 150L/h, 200L/h, 250L/h, 300L/h, at those conditions, the outlet H2S concentrations were lower than 8mg/m3 and the H2S removal efficiencies were more than 98%. The optimum gas retention time was 12.37s, corresponding to the inlet flow rate of 200L/h, at this time, even if the inlet H2S concentration as high as 700mg/m3, the removal efficiency could be still more than 98%, the outlet concentration of H2S was only 13.1mg/m3. The maximum inlet volume load was 130g/(m3•h), in this condition, the outlet concentration of H2S could be controlled below 12mg/m3, the removal efficiency could above 98.4%.

Experimental Investigation of Pressure Fluctuations on Inner Wall of a Centrifugal Pump

2019 ◽  
Vol 36 (4) ◽  
pp. 401-410 ◽  
Author(s):  
Xiao-Qi Jia ◽  
Bao-Ling Cui ◽  
Zu-Chao Zhu ◽  
Yu-Liang Zhang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Pressure Fluctuation ◽  
Pressure Fluctuations ◽  
High Flow ◽  
Low Flow ◽  
Centrifugal Pumps ◽  
Flow Rates ◽  
Pressure Distributions ◽  
Blade Passing Frequency

Abstract Affected by rotor–stator interaction and unstable inner flow, asymmetric pressure distributions and pressure fluctuations cannot be avoided in centrifugal pumps. To study the pressure distributions on volute and front casing walls, dynamic pressure tests are carried out on a centrifugal pump. Frequency spectrum analysis of pressure fluctuation is presented based on Fast Fourier transform and steady pressure distribution is obtained based on time-average method. The results show that amplitudes of pressure fluctuation and blade-passing frequency are sensitive to the flow rate. At low flow rates, high-pressure region and large pressure gradients near the volute tongue are observed, and the main factors contributing to the pressure fluctuation are fluctuations in blade-passing frequency and high-frequency fluctuations. By contrast, at high flow rates, fluctuations of rotating-frequency and low frequencies are the main contributors to pressure fluctuation. Moreover, at low flow rates, pressure near volute tongue increases rapidly at first and thereafter increases slowly, whereas at high flow rates, pressure decreases sharply. Asymmetries are observed in the pressure distributions on both volute and front casing walls. With increasing of flow rate, both asymmetries in the pressure distributions and magnitude of the pressure decrease.

A new method for prediction of the acoustic performance and design parameter sensitivity analysis of multi-chamber perforated resonators with an irregular cross-section

2021 ◽  
pp. 1-24
Author(s):  
Rong Guo ◽  
Zanzan Sun ◽  
Zhen Huang ◽  
Rui Luo
Keyword(s):  
Theoretical Prediction ◽  
Cross Section ◽  
Flow Rate ◽  
New Method ◽  
Frequency Noise ◽  
Acoustic Characteristics ◽  
Inlet Flow ◽  
Acoustic Performance ◽  
Inlet Flow Rate ◽  
Prediction Approach

Abstract Aiming at reducing the high-amplitude and wide-frequency noise in charged air intake system of the powertrain, this paper proposes a new method for predicting the acoustic characteristics of an irregular cross-section multi-chamber perforated resonator under flow conditions. By this method, the presence of three-dimensional sound waves and the effects of higher-order modes are considered, and the acoustic performance of the resonator can be evaluated through the computation of transmission loss. Moreover, by discretizing the cross-section of perforated resonator and extracting node information, this method can solve the acoustic characteristics of the perforated resonator with any cross-section. Based on the transfer matrix method, the quadrupole parameters of each chamber are obtained. Then the acoustic characteristics of the multi-chamber perforated resonator could be calculated. The theoretical prediction data and the experimental data have been compared and the results show good agreement within the entire frequency range, which verifies the accuracy of the theoretical prediction approach. Based on this prediction approach, the influence of section ratio, structure parameters and inlet flow rate on the acoustic characteristics of the resonator is explored. The results show that when the structural parameters change, the peak resonance frequency of the resonator will have a regular shift. With the increase of the inlet flow rate, the main frequency band of sound attenuation will decrease significantly. The theoretical method developed in this work can be used for the calculation and optimization of multi-chamber resonators in various applications.

Flow Analysis of a Hydrocyclone Designed to High Oil Content Application

2009 ◽  
Author(s):  
G. M. Raposo ◽  
A. O. Nieckele
Keyword(s):  
Experimental Data ◽  
Flow Rate ◽  
Oil Content ◽  
Flow Analysis ◽  
Turbulence Models ◽  
Reynolds Stress Model ◽  
Tangential Component ◽  
Inlet Flow ◽  
Unit Process ◽  
Inlet Flow Rate

Development of small size and weight separation equipment are crucial for the petroleum off-shore exploration. Since centrifugal fields are several times stronger than the gravity field, cyclonic separation has became very important as a unit process for compact gas-liquid, liquid-liquid and solid-liquid separation. The major difference between the various cyclones is their geometry. Cyclone optimization for different uses is, every year, less based on experiments and more based on mathematical models. In the present work, the flow field inside high oil content hydrocyclones is numerically obtained with FLUENT. The performance of two turbulence models, Reynolds Stress Model (RSM) and Large Eddy Simulation (LES), to predict the flow inside a high oil content hydrocyclone, is investigated by comparing the results with experimental data available in the literature. All models overpredicted the tangential component, especially at the reverse cone region. However, the prediction of the tangential turbulent fluctuations with LES was significant better than the RSM prediction. The influences of the inlet flow rate and hydrocyclone length in the flow were also evaluated. RSM model was able to foresee correctly, in agreement with experimental data, the correct tendency of pressure drop reduction with decreasing inlet flow rate and increasing length.

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