Strategies for Isothermal, Real-Time, Transient Pipeline Models in Shut-In Conditions

2018 ◽  
Author(s):  
Norense Okungbowa ◽  
Trent Brown
Keyword(s):  
Real Time ◽  
Thermal Effects ◽  
Burial Depth ◽  
Fluid Temperature ◽  
Soil Density ◽  
Soil Thermal Conductivity ◽  
Buried Pipelines ◽  
Isothermal Model ◽  
Secondary Importance ◽  
Soil Heat Capacity

Onshore, liquid pipelines are often modeled with isothermal models. Ignoring thermal effects is justified because thermal effects are of secondary importance and because the data, such as burial depth, soil thermal conductivity, soil heat capacity, and soil density, required to accurately predict thermal behavior in buried pipelines is not known accurately. In addition, run speeds are faster for isothermal models than for rigorous thermal models, which is particularly important in real-time models. One condition where thermal effects become important is when a pipeline is shut-in. Pumps increase the temperature of the fluid, so the fluid temperature is, on average, greater than ambient temperature. When a pipeline is shut-in, the temperature decreases causing a corresponding decrease in pressure. Since an isothermal model does not account for this behavior, the decreasing pressure can be misinterpreted as a leak. This paper discusses a strategy for correcting the model to properly account for the behavior in shut-in conditions. The strategy is applied to real-time pipeline models using Synergi Pipeline Simulator (SPS), although the method is applicable to any isothermal model.

Thermal Analysis of Offshore Buried Pipelines Through Experimental Investigations and Numerical Analysis

2016 ◽  
Author(s):  
Suvra Chakraborty ◽  
Vandad Talimi ◽  
Mohammad Haghighi ◽  
Yuri Muzychka ◽  
Rodney McAffee
Keyword(s):  
Numerical Analysis ◽  
Heat Loss ◽  
Transient Response ◽  
Oil And Gas ◽  
Burial Depth ◽  
Fluid Temperature ◽  
Buried Pipeline ◽  
Buried Pipelines ◽  
Arctic Regions ◽  
Backfill Soil

Modeling of heat loss from offshore buried pipelines is one of the prime concerns for Oil and Gas industries. Offshore Oil and Gas production and thermal modeling of buried pipelines in arctic regions are challenging tasks due to environmental conditions and hazards. Flow properties of Oil and Gas flowing through the pipelines in arctic regions are also affected due to freezing around pipelines. Solid formation in the production path can have serious implications on production. Heavy components of crude oil start to precipitate as wax crystal when the fluid temperature drops. Gas hydrates also form when natural gas combines with free water at high pressure and low temperature. Pipeline burial and trenching in some offshore developments are now one of the prime methods to avoid ice gouge, ice cover, icebergs, and other threats. Long pipelines require more thermal management to deliver production to the sea surface. Significant heat loss may occur from offshore buried pipelines in the forms of heat conduction and natural convection through the seabed. The later can become more prominent where the backfill soil is loose or sandy. The aim of this paper is to provide an insight of modeling and conducting the experiments using different parameters with numerical analysis results support to investigate the heat loss from offshore buried pipelines. This paper also provides validation of the outputs from benchmark tests with analytical models available for theoretical shape factor at constant temperature and constant heat flux boundary conditions. These theoretical models have limitations such as the assumption of uniform soil properties around the buried pipeline, isothermal outer surface of the buried pipeline and soil surface. Degree of saturation of surrounding medium can play a significant role in the thermal behavior of fluid travelling through the backfill soil. This paper presents several steady states and transient response analysis describing some influential geotechnical parameters along with test procedures and numerical simulations using CFD to model the heat loss for different parameters such as burial depth, backfill soil, trench geometries etc. This paper also shows the transient response for several shutdown (cooldown) tests performed in the saturated sand medium. The statistical and uncertainty analysis performed from the experimental outputs also ensure the legitimacy of the experimental model. The outcomes of this research will provide valuable experimental data and numerical predictions for offshore pipeline design, heat loss from buried pipelines in offshore conditions, and efficient model to mitigate the flow assurance issues e.g. wax and hydrates.

A Real-Time AC/DC Measurement Technique for Assessment of AC Corrosion of Buried Pipelines

2012 ◽  
Author(s):  
Cindy X. Su ◽  
Luyao Xu ◽  
Frank Y. Cheng
Keyword(s):  
Real Time ◽  
Current Density ◽  
Steel Surface ◽  
Steel Corrosion ◽  
Buried Pipelines ◽  
Total Potential ◽  
Ac Current ◽  
Potential Alternative ◽  
Current Densities ◽  
Ac Interference

In this work, a real-time AC/DC signal data acquisition (DAQ) technique was developed, which is capable of separating the DC and AC potential components from the recorded total potential, providing mechanistic information about the steel corrosion in the presence of AC interference. It was found that the corrosion of the steel is enhanced by the applied AC current density from 0 to 400 A/m2. With the further increase to 600 A/m2 and 800 A/m2, the corrosion rate of the steel decreases, which is attributed to passivation of the steel at sufficiently high AC current densities, and a compact film is formed on the steel surface. Moreover, the derived mathematic relationships between AC potential and AC current density provides a potential alternative to determine AC current density on pipelines based on measurements of AC potential in the field.

The Long Take, Mastery

2016 ◽  
Vol 70 (1) ◽  
pp. 48-53
Author(s):  
Cyril Béghin ◽  
Mark Cohen
Keyword(s):  
New York ◽  
Real Time ◽  
One Dimension ◽  
Secondary Importance ◽  
Everyday Action ◽  
Jeune Fille

One dimension of the long take in Chantal Akerman's films is rarely cited for its own sake: that the long take records “real time,” that it inscribes and sublimates the banality of an everyday action by respecting its duration, that it bears witness to a waiting become infinite, one open to various historical dimensions, that it portrays faces and bodies in the fragile persistence of an emotion. All of this is accurate, but is of somewhat secondary importance next to the primary relation the image establishes; whether she is filming people or things, alienating interiors or deserted landscapes, Akerman uses duration to summon the viewer to an aesthetic relation. This article discusses the following Akerman films in light of the filmmaker's use of the long take: Portrait d'une jeune fille de la fin des années 60 à Bruxelles (1994), Toute une nuit (1982), Un divan à New York (1996), Nuit et jour (1991), La Captive (2000), News from Home (1977), Là-bas (2006), La folie Almayer (2011), No Home Movie (2015), Je tu il elle (1974), L'Homme à la valise (2004), Le Déménagement (1992), D'Est (1993), and Les rendez-vous d'Anna (1978).

scholarly journals The Influence of Burial Depth and Soil Thermal Conductivity on Heat Transfer in Buried CO2 Pipelines for CCS: A Parametric Study

2020 ◽  
Author(s):  
Babafemi Olugunwa ◽  
Julia Race ◽  
Tahsin Tezdogan
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Steady State ◽  
Thermal Resistance ◽  
Parametric Study ◽  
Flow Assurance ◽  
Burial Depth ◽  
Soil Thermal Conductivity ◽  
Dense Phase ◽  
Pipeline Transportation

Abstract Pipeline heat transfer modelling of buried pipelines is integral to the design and operation of onshore pipelines to aid the reduction of flow assurance challenges such as carbon dioxide (CO2) gas hydrate formation during pipeline transportation of dense phase CO2 in carbon capture and storage (CCS) applications. In CO2 pipelines for CCS, there are still challenges and gaps in knowledge in the pipeline transportation of supercritical CO2 due to its unique thermophysical properties as a single, dense phase liquid above its critical point. Although the design and operation of pipelines for bulk fluid transport is well established, the design stage is incomplete without the heat transfer calculations as part of the steady state hydraulic and flow assurance design stages. This paper investigates the steady state heat transfer in a buried onshore dense phase CO2 pipelines analytically using the conduction shape factor and thermal resistance method to evaluate for the heat loss from an uninsulated pipeline. A parametric study that critically analyses the effect of variation in pipeline burial depth and soil thermal conductivity on the heat transfer rate, soil thermal resistance and the overall heat transfer coefficient (OHTC) is investigated. This is done using a one-dimensional heat conduction model at constant temperature of the dense phase CO2 fluid. The results presented show that the influence of soil thermal conductivity and pipeline burial depth on the rate of heat transfer, soil thermal resistance and OHTC is dependent on the average constant ambient temperature in buried dense phase CO2 onshore pipelines. Modelling results show that there are significant effects of the ambient natural convection on the soil temperature distribution which creates a thermal influence region in the soil along the pipeline that cannot be ignored in the steady state modelling and as such should be modelled as a conjugate heat transfer problem during pipeline design.

Thermogasodynamic Analysis of the Segmented Annular Seal

2020 ◽  
Vol 143 (7) ◽  
Author(s):  
Samia Dahite ◽  
Mihai Arghir
Keyword(s):  
Parametric Study ◽  
Thermal Effects ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Leading Edge ◽  
Test Case ◽  
Isothermal Model ◽  
Pocket Depth ◽  
Annular Seal ◽  
Three Degrees Of Freedom

Abstract The present work deals with the thermogasodynamic analysis of the segmented annular seal provided with Rayleigh pockets. The paper is a continuation of the work presented Arghir, M., and Mariot, A. (2017, “Theoretical Analysis of the Static Characteristics of the Carbon Segmented Seal,” ASME J. Tribol., 139(6), p. 062202.) where an isothermal model of the segmented annular seal was first presented. Each segment had three degrees-of-freedom, and its static position was obtained by solving the nonlinear equations of equilibrium. Thermal effects are now introduced by considering a simplified form of the energy equation in the thin gas film coupled with the three dimensional heat transfer in a segment of the seal and in the rotor. An efficient numerical algorithm is developed. A parametric study was performed for a segmented annular seal with pockets taken from the literature and operating with air. First, a test case proved the necessity of considering three degrees-of-freedom for the segment and not only its radial displacement. The parametric study was then performed for two different pocket depths, two pressure differences, and different rotation speeds. The results showed a non-uniform heating with larger temperatures at the leading edge of the segment where the minimal film thickness occurs. Heating is proportional to the pocket depth that lowers the lift force of the segment and to the pressure difference that closes the seal.

Analysis of Thermal Effects in a Cavitating Orifice Using Rayleigh Equation and Experiments

2009 ◽  
Author(s):  
Maria Grazia De Giorgi ◽  
Daniela Bello ◽  
Antonio Ficarella
Keyword(s):  
Thermal Effects ◽  
High Speed ◽  
Complex Geometry ◽  
Internal Flow ◽  
Rayleigh Equation ◽  
Fluid Temperature ◽  
Dimensional Model ◽  
Cloud Cavitation ◽  
One Dimensional ◽  
Numerical Predictions

The focus of this research is the experimental and analytical study of the cavitation phenomena in internal flows in presence of thermal effects. Experiments have been done on water and nitrogen cavitating flow in orifices. Transient growth process of the cloud cavitation induced by flow through the throat is observed using high-speed video images and analyzed by pressure signals. Cavitation of thermo-sensible fluid, as cryogenic fluid, presents additional complexities (as compared to that in water) because thermal effects are important. The different cavitating behavior at different temperature and different fluid is related to the bubble dynamic inside the flow. To investigate possible explanations for the influence of fluid temperature on cavitating internal flow, initially, a steady, quasi-one dimensional model has been implemented. The nonlinear dynamics of the bubbles has been modeled by Rayleigh-Plesset equation. In the case of nitrogen, thermal effects in the Rayleigh equation are taken into account by considering the vapor pressure at the actual bubble temperature Tc, which is different from the liquid temperature T far from the bubble. A convective approach has been used to estimate the bubble temperature. The quasi-steady one dimensional model can be extensively used to conduct parametric studies useful for fast estimation of the overall performance of any geometric design. For complex geometry, three-dimensional CFD codes are necessary. In the present work comparison have been done with numerical predictions by the CFD Fluent code in which a simplified form of the Rayleigh equation taking into account thermal effects has been implemented by external user routines.

Thermal Effects in Cryogenic Liquid Annular Seals—Part I: Theory and Approximate Solution

1993 ◽  
Vol 115 (2) ◽  
pp. 267-276 ◽  
Author(s):  
Zhou Yang ◽  
Luis San Andres ◽  
Dara W. Childs
Keyword(s):  
Heat Transfer ◽  
Analytical Solution ◽  
Thermal Effects ◽  
Approximate Analytical Solution ◽  
Cryogenic Liquid ◽  
Bulk Flow ◽  
Absolute Pressure ◽  
Fluid Temperature ◽  
Numerical Predictions ◽  
Annular Seals

A thermohydrodynamic (THD) analysis is introduced for calculation of the performance characteristics of cryogenic liquid annular seals in the turbulent flow regime. A full-inertial bulk-flow model is advanced for momentum conservation and energy transport. The liquid material properties depend on the local absolute pressure and temperature. Heat flow to the rotor and stator is modeled by bulk-flow heat transfer coefficients. An approximate analytical solution is obtained to the governing equations when the seal operates at a steady-state and concentric condition. The temperature-rise in the fluid film of a cryogenic liquid seal is found to be composed of four sources due to viscous dissipation, pressure extrusion work, surface heat transfer and kinetic energy variation. For incompressible adiabatic flows, the fluid temperature rises linearly along the axial direction. The approximate analytical solution provides a useful tool for preliminary design and a better understanding of seal performance. Full numerical predictions of load, leakage, temperature, and rotordynamic coefficients for a high speed liquid oxygen seal are given in Part II to show the importance of thermal effects on seal performance. The accuracy of the approximate concentric seal analysis is then demonstrated by comparison to the results from the full numerical solution.

scholarly journals Investigating the Factors That Reduce the Urban Gas Pipeline Vulnerability to Explosion Threats

2019 ◽  
Author(s):  
Mohammad reza Fallah Ghanbari ◽  
Mohammad Eskandari ◽  
Ali Alidoosti
Keyword(s):  
Soft Soil ◽  
Shell Element ◽  
Friction Angle ◽  
Burial Depth ◽  
Gas Pipelines ◽  
Three Dimensional Model ◽  
Buried Pipelines ◽  
Burial Site ◽  
Pipe System ◽  
Abaqus Software

Introduction: Buried pipelines used to distribute water, gas, oil, and etc. are considered as one of the vital arteries. The experiences of the past wars have confirmed that the invading country focuses on bombing and destroying vital centers, and that gas pipelines can be a source of serious personal and financial losses as an important transmission arteries during war in the event of damage Methods: The vulnerability of buried urban gas pipelines to explosion was determined and the methods for reducing the vulnerability of pipelines were investigated. To this end, the three-dimensional model of the soil-pipe system in ABAQUS software was used to study the effect of factors affecting the pipe behavior, including pipe diameters, diameter to pipe thickness, internal friction angle of soil, soil type, amount of explosives, depth of buried, the distance of explosion site to the pipe burial site, has been investigated on the pipe deformation capacity according to the ALA regulation. The soil was modeled using Solid three elements and shell element. For parametric studies, analyses were performed by the finite element method using ABAQUS software 6.10.1. Results: Studies were conducted for 4 and 12 inch diameter, diameter/thickness ratio of 26, 21 and 35, burial depth of 1, 2, 3 and 4 meters, the explosive charge of 15, 30, 45, 60 and 200 kg TNT and for soil material, hard, soft and clay sands. The results showed that proper burial depth had the most effect in reducing the vulnerability of pipelines against explosive threats. By increasing the pipe thickness and increasing the diameter and applying soft soil around the pipe, a better behavior of the pipe was observed during the explosion Conclusion: To reduce the vulnerability of gas pipelines against explosive threats, the use of buried pipelines has a greater effect on reducing damage due to explosion compared to other parameters, and it is recommended to use this method to increase the resilience of highly important gas pipelines.

scholarly journals An Investigation of Effects and Safety of Pipelines due to Twin Tunneling

2021 ◽  
Vol 2021 ◽  
pp. 1-15
Author(s):  
Shao Yu ◽  
Riyan Lan ◽  
Junhui Luo ◽  
Zhibo Duan ◽  
Shaokun Ma
Keyword(s):  
Soil Parameters ◽  
Centrifuge Model Test ◽  
Burial Depth ◽  
Buried Pipelines ◽  
Soil Stiffness ◽  
Maximum Settlement ◽  
Dimensionless Analysis ◽  
Bending Strain ◽  
Calculation Results ◽  
Subway Tunnels

To efficiently and accurately predict the effects of twin tunneling on adjacent buried pipelines, the effects of upward and downward relative pipeline-soil interactions were considered. A series of numerical parametric studies encompassing 8640 conditions were performed to investigate the responses of a pipeline to twin tunneling. Based on the dimensionless analysis and normalized calculation results, the concept of equivalent relative pipeline-soil stiffness was proposed. Additionally, expressions for the relative pipeline-soil stiffness and relative pipeline curvature and for the relative pipeline-soil stiffness and relative pipeline settlement were established, along with the related calculation plots. Relying on a comparison of prediction results, centrifuge model test results, and field measured results, the accuracy and reliability of the obtained expressions for predicting the bending strain and settlement of adjacent buried pipelines caused by twin tunneling were validated. Based on the calculation method, the maximum bending strain and maximum settlement of pipelines can be calculated precisely when the pipeline parameters, burial depth, soil parameters, and curve parameters of ground settlement due to tunneling are provided. The proposed expressions can be used not only to predict the maximum bending strain and maximum settlement of pipelines caused by single and twin tunneling but also to evaluate the effects of single and twin tunneling on the safety of existing buried pipelines. The relevant conclusions of this article can also provide a theoretical basis for the normal service of buried pipelines adjacent to subway tunnels.

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