Optimizing the Design of Unbonded Flexible Pipelines With More Realistic Predictions of pH and H2S Content in the Annulus

2017 ◽  
Author(s):  
Li Ke ◽  
Carol Taravel-Condat ◽  
Jean Kittel ◽  
Rémy Mingant ◽  
Claude Duret-Thual ◽  
...  
Keyword(s):  
Ph Monitoring ◽  
Stationary Phases ◽  
Oil Field ◽  
Low Flow ◽  
Small Scale ◽  
Flow Rates ◽  
Dissolved Iron ◽  
Flexible Pipes ◽  
Steel Grades

Due to its high metallic confinement, the annulus of unbonded flexible pipelines is a specific and mild corrosive medium for carbon steel armour wires. This environment presents high supersaturation levels of dissolved iron, leading to pH values far above thermodynamic equilibrium. Furthermore, the permeation of acidic gases (such as CO2 and H2S) through the polymer pressure sheath occurs at very low flow rates. Since the annulus is supersaturated with dissolved iron, part of the H2S is consumed as it slowly arrives into the annulus. Therefore, the annular medium contains low levels of gas far below those predicted by standard thermodynamic models, and less H2S is available to trigger sour cracking. The recent development of harsher oil field conditions (higher water depths, increased CO2 content, presence of H2S...) induced the need to refine the design of flexible pipes to propose more cost effective solutions. As pH and H2S content are key parameters for the selection of steel grades, taking into account the supersaturation and the H2S consumption in the annulus allows major optimization of flexible pipes by using for instance steel grades with higher strength. Therefore, extensive experimental work was conducted over the past years to better characterize the annulus and predict more realistic pH and H2S levels. In this paper, the following developments are presented: – A kinetic corrosion model named FlexCor was derived from numerous corrosion tests done at various CO2 pressures in confined configuration, with in-situ pH monitoring. These tests were performed over long durations (3 months) in order to capture the effective long term supersaturated pH. The kinetic model is able to simulate the transient and stationary phases of the supersaturated pH evolution up to 45 bara of CO2, providing a good fit with the experimental data. The tests also demonstrated that the annulus environment remains supersaturated even at high CO2 partial pressures. – A methodology taking into account the H2S consumption was developed based on extensive long-term small scale and full scale testing (> 2 years), where low flow rates of H2S were imposed. The experimental results show that H2S consumption is far from negligible, even when the annulus is not fully flooded. This H2S consumption methodology was certified by an Independent Verification Agency and is now being applied on commercial projects.

Dynamic control of a continuous-inflow SBR with time-varying influent loading

2001 ◽  
Vol 43 (3) ◽  
pp. 107-114 ◽  
Author(s):  
R.-F. Yu ◽  
S.-L. Liaw ◽  
B.-C. Cho ◽  
S.-J. Yang
Keyword(s):  
Ph Monitoring ◽  
Batch Reactor ◽  
Dynamic Control ◽  
Fixed Time ◽  
Treatment Costs ◽  
Small Scale ◽  
Time Varying ◽  
Flow Rates ◽  
Substrate Removal ◽  
Sequential Control

The conventional sequential control of Sequencing Batch Reactor (SBR) is designed with fixed time periods for various operation phases. However, both of the flow rates and qualities of influent vary over time, therefore, a big capacity of wastewater equalization unit is required to cope with influent variability. Such an equalization unit increases the total treatment costs of the system, especially in a small-scale wastewater treatment system. Moreover, in using a SBR treating a time-varying influent loading with conventional sequential control, the system performance cannot be optimized. This paper presents the application of on-line ORP and pH monitoring to dynamically control a continuous-inflow SBR with time-varying loading of influent flow rates and water qualities. Experiential results show that the dynamic controlled SBR revealed not only achieved better substrate removal efficiencies, but also reduced treatment costs.

Scenario-Based Robustness Analysis of Optimized I.D.E.-Style Treadle Pump Designs

2016 ◽  
Author(s):  
Christopher McComb ◽  
Nathan G. Johnson ◽  
Brandon T. Gorman
Keyword(s):  
Developing Countries ◽  
Service Providers ◽  
Operating Cost ◽  
Robustness Analysis ◽  
Development Aid ◽  
Low Flow ◽  
Entrepreneurial Activity ◽  
Small Scale ◽  
Pareto Optimal ◽  
Flow Rates

Poverty affects hundreds of millions of people globally. Market-based strategies can help alleviate poverty in developing countries by encouraging entrepreneurial activity and have the potential to be more effective than traditional approaches, such as development aid from countries or non-governmental organizations. Development organizations often target the agricultural sector because of the prevalence of subsistence and small-scale farming, particularly in rural regions of developing countries. Improving the reliability of irrigation techniques can help farmers expand out of primarily subsistence farming and begin to sell a portion of their crop, thus achieving the objectives of market-based poverty alleviation. Human-powered pumps are a popular tool used in irrigation because they require low capital cost and negligible operating cost. Previous work provided a model for finding Pareto-optimal IDE-style treadle pump designs. This work utilizes that model to produce a dense set of Pareto-optimal designs, and then investigates the robustness of the designs by simulating their performance in a variety of modified use scenarios. Our results show that pumps optimized for low flow rates (less than 3.0 L/s) are highly robust, particularly with respect to age-related changes in the operator’s stature or mobility. In addition, these pumps can operate with near-optimal efficiency across a variety of target flow rates and well depths. These pumps are ideal for single family use or for shared use amongst multiple families in a village. Pumps optimized for flow rates greater than 3.0 L/s are less robust with respect to changes of operator stature (experiencing decreases in flow rate of up to 60%) but may be suitable for use on farms or by service providers.

An Elastomeric Micrometering System for the Controlled Administration of Drugs

1977 ◽  
Vol 50 (5) ◽  
pp. 959-968 ◽  
Author(s):  
J. C. Wright ◽  
R. G. Buckles ◽  
J. T. Dunn ◽  
H. M. Leeper ◽  
S. I. Yum
Keyword(s):  
Silicone Rubber ◽  
Hoop Stress ◽  
Control Flow ◽  
Low Flow ◽  
Rubber Tubing ◽  
Flow Rates ◽  
Fluid Delivery ◽  
Elastomeric Materials ◽  
Stable Flow

Abstract When drugs are infused, it is often necessary to minimize the volume of fluid delivered. Fluid delivery rates of 1 cm3/h or less are frequently desirable; however, the accurate metering of fluids at such low flow rates to the human body has been difficult to accomplish. The metering devices most commonly used to control flow rate from a constant-pressure source have been micrometer valves, clamped tubes, capillaries, and porous plugs. Each of these devices has specific disadvantages : micrometer valves are expensive and bulky, clamped tubes are not stable for long-term infusion and present a hazard of greatly fluctuating flow rates, capillary tubes are subject to particle blockage and are not adjustable, and porous plugs suffer from lack of adjustability. Recently a valve made of extruded silicone rubber rod with axial holes was reported to yield stable flow rates; it was adjusted by placement in a plastic clamp. A new low-infusion-rate metering system has been developed to overcome the above deficiencies. This system consists of axially aligned polyurethane fibers contained within the lumen of a length of silicone rubber tubing. The fibers fill the lumen to the extent that they are subjected to a compressive hoop stress by the tubing. The assembly represents two elastomeric materials in states of strain, exerting equal and opposite stresses on each other. The elastomeric tubular assembly is contained in a rigid, adjustable, U-shaped enclosure that controls the deformation of the assembly. While other elastomeric materials would be suitable for the elastomeric valving system, we report here on our experience with polyurethane fibers and silicone rubber tubing. These materials were selected for their expected compatibility with most aqueous drugs and their availability.

Qualification of Sealing System for Flexible Pipes Using a Self-Energized Gasket

2018 ◽  
Author(s):  
Christian Wang ◽  
Martin Halsteen ◽  
Jesper Ries
Keyword(s):  
System Integration ◽  
Performance Test ◽  
Full Scale ◽  
Third Party ◽  
Small Scale ◽  
Flexible Pipes ◽  
Sealing Material ◽  
High Pressure Co2 ◽  
Current Design

In order to meet higher technical demands designing flexible pipes at higher pressures and higher temperatures for deeper water depths NOV has introduced and qualified a new sealing system that is self-energized. The sealing material has been qualified and tested in different fluids. The sealing system has shown good functionality at higher pressures as well as at lower pressures. The qualification of the sealing system has been based on multiple full-scale and mid-scale tests according to Recommended Practice API 17B and small-scale tests on the elastomer material including long-term ageing tests and rapid gas decompression tests in high pressure CO2 up to 900 bar. The recommendations of RP API 17B used in the industry has its limitation with regards to qualification of a new sealing system. This paper gives an overview how to qualify a new sealing system on an existing product range achieving different technology readiness levels according to Recommended Practice API 17N from TRL1 up to TRL5. TRL5 covers system integration testing by full-scale testing of flexible pipes such as burst test, tension-pressure test, tension-tension test and deep immersion performance test. All qualification tests have been witnessed by a third-party Bureau Veritas and the enhanced sealing system has archived a TRL5 statement within its current design envelope.

scholarly journals Low Flow and Drought in a German Low Mountain Range Basin

Water ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 316
Author(s):  
Paula Farina Grosser ◽  
Britta Schmalz
Keyword(s):  
Scale Effects ◽  
Low Flow ◽  
Temperate Climate ◽  
Federal State ◽  
Small Scale ◽  
Mountain Range ◽  
Short Term ◽  
Low Mountain Range

Rising temperatures and changes in precipitation patterns in the last decades have led to an increased awareness on low flow and droughts even in temperate climate zones. The scientific community often considers low flow as a consequence of drought. However, when observing low flow, catchment processes play an important role alongside precipitation shortages. Therefore, it is crucial to not neglect the role of catchment characteristics. This paper seeks to investigate low flow and drought in an integrative catchment approach by observing the historical development of low flows and drought in a typical German low mountain range basin in the federal state of Hesse for the period 1980 to 2018. A trend analysis of drought and low flow indices was conducted and the results were analyzed with respect to the characteristics of the Gersprenz catchment and its subbasin, the Fischbach. It was shown that catchments comprising characteristics that are likely to evoke low flow are probably more likely to experience short-term, seasonal low flow events, while catchments incorporating characteristics that are more robust towards fluctuations of water availability will show long-term sensitivities towards meteorological trends. This study emphasizes the importance of small-scale effects when dealing with low flow events.

scholarly journals A new instrument to measure plot-scale runoff

2014 ◽  
Vol 4 (2) ◽  
pp. 589-608 ◽  
Author(s):  
R. D. Stewart ◽  
Z. Liu ◽  
D. E. Rupp ◽  
C. W. Higgins ◽  
J. S. Selker
Keyword(s):  
Water Level ◽  
Surface Runoff ◽  
Large Scale ◽  
Multiple Scales ◽  
Low Cost ◽  
Low Flow ◽  
Flow Rates ◽  
New Instrument ◽  
Water Level Measurements

Abstract. Accurate measurement of the amount and timing of surface runoff at multiple scales is needed to understand fundamental hydrological processes. At the plot-scale (i.e., length scales on the order of 1 to 10 m) current methods for direct measurement of runoff either store the water in a collection vessel, which is unconducive to long-term monitoring studies, or utilize expensive installations such as large-scale tipping buckets or flume/weir systems. We developed an alternative low-cost, robust and reliable instrument to measure runoff that we call the "Upwelling Bernoulli Tube" (UBeTube). The UBeTube instrument is a pipe with a slot machined in its side that is installed vertically at the base of a runoff collection system. The flow rate through the slot is inferred by measuring the water height within the pipe. The geometry of the slot can be modified to suit the range of flow rates expected for a given site; we demonstrate a slot geometry which is capable of measuring flow rates across more than three orders of magnitude (up to 300 L min−1) while requiring only 30 cm of hydraulic head. System accuracy is dependent on both the geometry of the slot and the accuracy of the water level measurements. With an off-the-shelf pressure transducer sensor, the mean theoretical error for the demonstrated slot geometry was ~17% (ranging from errors of more than 50% at low flow rates to less than 2% at high flow rates), while the observed error during validation was 1–25%. A simple correction factor reduced this mean error to −14%, and further reductions in error could be achieved through the use of taller, narrower slot dimensions (which requires greater head gradients to drive flow) or through more accurate water level measurements. The UBeTube device has been successfully employed in a long-term rainfall-runoff study, demonstrating the ability of the instrument to measure surface runoff across a range of flows and conditions.

An Experimental Investigation of a Temperature Controlled Vapor Supply System

2013 ◽  
Author(s):  
Robert G. Ryan ◽  
Jeffrey Bunting
Keyword(s):  
Constant Pressure ◽  
Heat Transfer Process ◽  
Supply System ◽  
Low Flow ◽  
Small Scale ◽  
Mechanical Pressure ◽  
Vapor Source ◽  
Flow Rates ◽  
Supply Tank ◽  
Temperature Levels

A variety of applications require a constant pressure vapor supply for processes such as purging fluid systems. A typical design would use a high pressure tank of gas (e.g. helium) along with a mechanical pressure regulator to deliver a constant pressure flow. An alternative concept for the vapor source is to use a tank containing a saturated liquid-vapor mixture. As the vapor is drawn off of the top of the tank, the temperature of the mixture is controlled to maintain the desired vapor delivery pressure. The potential advantage of this approach is that the vapor supply system can be designed to be lighter, more compact, and safer. An experiment was designed to test the practicality of this concept in a small scale system. Carbon dioxide was chosen for the saturated mixture due to its availability, safety, and desirable operating pressures near ambient temperature levels. The apparatus was designed to allow for the measurement of relevant temperatures and pressures over a range of vapor delivery flow rates. Temperature control of the supply tank was accomplished by submergence in an ice bath. The experimental results confirm that this type of system can produce a well regulated vapor supply at low flow rates, but fails to produce steady pressures at higher delivery flows due to limitations of the heat transfer process in the supply tank.

Numerical Study of Premixed Combustion of Methane Stabilized on Porous Medium

2016 ◽  
Author(s):  
Valerio Giovannoni ◽  
Rajnish N. Sharma ◽  
Robert R. Raine
Keyword(s):  
Porous Medium ◽  
Numerical Study ◽  
Burning Velocity ◽  
Combustion Process ◽  
Heat Losses ◽  
Low Flow ◽  
Small Scale ◽  
High Porosity ◽  
Flow Rates ◽  
Flame Holder

The present study focuses on the numerical analysis of the combustion process occurring in a small scale cylindrical combustion chamber using a commercial computational code. The chosen diameter is 18 mm, being the same as the flat flame regenerative combustor currently under experimental investigation by the author (Giovannoni), and it includes a 10 mm thick porous flame holder and a 1 mm thick stainless steel outer wall. A 17 species and 73 reactions skeletal mechanism related to methane oxidation is employed for the simulations. A parametric study is performed and results in terms of temperature profiles, major species’ concentrations and flow velocities are presented. Results show that the flame holder can considerably affect combustion and heat losses from the combustor. In particular at low flow rates, when the laminar burning velocity is much higher than the flow velocity, heat is lost mainly through the flame holder to the walls and to the surroundings. At high flow rates the flame appears to be slightly lifted from the porous medium and heat is mainly dispersed to the walls. This causes preheating of the mixture upstream of the combustion through axial conduction in the wall, achieving superadiabatic temperature. It is also clear from the simulations that employing a flame holder with low thermal conductivity and high porosity yields benefits in limiting heat losses and in widening flammability limits.

scholarly journals A new instrument to measure plot-scale runoff

2015 ◽  
Vol 4 (1) ◽  
pp. 57-64 ◽  
Author(s):  
R. D. Stewart ◽  
Z. Liu ◽  
D. E. Rupp ◽  
C. W. Higgins ◽  
J. S. Selker
Keyword(s):  
Water Level ◽  
Surface Runoff ◽  
Large Scale ◽  
Multiple Scales ◽  
Low Cost ◽  
Low Flow ◽  
Flow Rates ◽  
New Instrument ◽  
Water Level Measurements

Abstract. Accurate measurement of the amount and timing of surface runoff at multiple scales is needed to understand fundamental hydrological processes. At the plot scale (i.e., length scales on the order of 1–10 m) current methods for direct measurement of runoff either store the water in a collection vessel, which is not conducive to long-term monitoring studies, or utilize expensive installations such as large-scale tipping buckets or flume/weir systems. We developed an alternative low-cost, robust and reliable instrument to measure runoff that we call the "Upwelling Bernoulli Tube" (UBeTube). The UBeTube instrument is a pipe with a slot machined in its side that is installed vertically at the base of a runoff collection system. The flow rate through the slot is inferred by measuring the water height within the pipe. The geometry of the slot can be modified to suit the range of flow rates expected for a given site; we demonstrate a slot geometry that is capable of measuring flow rates across more than 3 orders of magnitude (up to 300 L min−1) while requiring only 30 cm of hydraulic head. System accuracy is dependent on both the geometry of the slot and the accuracy of the water level measurements. Using a pressure sensor with ±7 mm accuracy, the mean theoretical error for the demonstrated slot geometry was ~17% (ranging from errors of more than 50% at low flow rates to less than 2% at high flow rates), while the observed error during validation was 1–25%. A simple correction factor reduced this mean error to 0–14%, and further reductions in error could be achieved through the use of taller, narrower slot dimensions (which requires greater head gradients to drive flow) or through more accurate water level measurements. The UBeTube device has been successfully employed in a long-term rainfall-runoff study, demonstrating the ability of the instrument to measure surface runoff across a range of flows and conditions.

Modelling of Waste Form Performance and System Release

1984 ◽  
Vol 44 ◽  
Author(s):  
Aaron Barkatt ◽  
Pedro B. Macedo ◽  
Barbara C. Gibson ◽  
Charles J. Montrose
Keyword(s):  
Aqueous Medium ◽  
High Flow ◽  
Waste Glass ◽  
Waste Form ◽  
Low Flow ◽  
Matrix Elements ◽  
Release Rates ◽  
Flow Rates ◽  
Quantitative Calculations

AbstractKinetic and thermodynamic approaches to the derivation of long-term release rates of species from defense waste glass are reviewed. It is concluded that at high flow rates kinetic factors are pre-dominant, while at low flow rates saturation of the aqueous medium with respect to major matrix elements, particularly with respect to silica present in the glass and in its alteration products, becomes a controlling factor. Quantitative calculations indicate that under likely repository conditions the release rates can be expected, in general, to fall below the NRC criterion of 10−5 yr−1.

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