Advances and Challenges in Purging Pipeline Sections: Field Measurements vs. 1D Purging Model

2020 ◽  
Author(s):  
Kamal K. Botros ◽  
Andrew Hawryluk ◽  
Dmitry Ryapolov
Keyword(s):  
Natural Gas ◽  
Safety Issue ◽  
Short Circuit ◽  
Gravity Current ◽  
Field Measurements ◽  
Interfacial Velocity ◽  
Threshold Velocity ◽  
Pipe Section ◽  
Purge Gas ◽  
Insight Into

Abstract Effective purging of air out of a pipeline section before commissioning by direct displacement with natural gas has been safely practiced for decades with the recognition that flammable interfacial mixing zone between the driving gas (behind) and the air (ahead) is inevitable. In cases when the purge velocity is below a threshold dictated by the gravity current velocity (defined in AGA Purging Principles and Practices, 2001), natural gas being lighter than air can in fact ride over air being the heavier gas and short circuit the flow path to the vent at the other end of the pipe section, thus trapping behind pockets of air that could potentially introduce risk of internal explosion with subsequent damage to the pipe section and pose a safety issue to field personnel. Therefore, maintaining the purge velocity above this threshold by a good margin has been a common practice in the purging procedure to-date. In fact, maintaining the purge velocity above the threshold can be controlled by the injection press or flow, where tools and dynamic purging models have been successfully developed and proven to be useful. However, AGA recommends that the drive purge gas pressure be limited to 689 kPag (100 psig) in the inlet purge line to the pipe section to avoid the risk of detonation. In some cases when the inlet purge line is relatively small compared to the main pipe section, this limit on the purge pressure would result in gas/air interfacial velocity much lower than the threshold velocity, hence stratification will occur. This paper provides insight into the possibility of increasing the purge pressure above AGA limit to avoid stratification, while conforming to the safety aspects related to detonation. A purge model is developed to overcome the shortcoming in AGA purge software that limits the purge pressure to maximum of 689 kPag (100 psig). Field trial was conducted to validate the model which demonstrated, as a proof of concept, a successful purge procedure with purge pressure = 5517 kPag (800 psig) in NPS 1.5 purge line to purge nitrogen out of NPS 42, 5.8 km section of a pipeline.

scholarly journals Customer Safety Perception during a Self-Collection Process at IKEA Warehouse Self-Service

2019 ◽  
Vol 9 (2) ◽  
pp. 4678-4683
Keyword(s):  
Quantitative Method ◽  
Service Management ◽  
Safety Issue ◽  
The Self ◽  
Customer Perception ◽  
Collection Process ◽  
Safety Perception ◽  
Shopping Experience ◽  
Self Service ◽  
Insight Into

This study examines the self-service management of IKEA warehouse. IKEA has managed to make its product and service more popular not only on price but by creating a unique shopping experience for the customer. The objective of this research is to investigate the customer perception towards the self-collection process at IKEA warehouse self-service. A quantitative method was adopted targeting the IKEA customer. 196 respondents participated in answering the questionnaire. The result of this study offers a preliminary insight into the safety issue of the warehouse self-service implementation.

scholarly journals Numerical Monitoring of Natural Gas Distribution Discrepancy Using CFD Simulator

2010 ◽  
Vol 2010 ◽  
pp. 1-23 ◽  
Author(s):  
Vadim E. Seleznev
Keyword(s):  
Natural Gas ◽  
Distribution System ◽  
Field Measurements ◽  
Identification Problem ◽  
Distribution Networks ◽  
Reference Points ◽  
Gas Distribution ◽  
Natural Gas Transmission ◽  
Minimum Discrepancy ◽  
Gas Supply

The paper describes a new method for numerical monitoring of discrepancies in natural gas supply to consumers, who receive gas from gas distribution loops. This method serves to resolve the vital problem of commercial natural gas accounting under the conditions of deficient field measurements of gas supply volumes. Numerical monitoring makes it possible to obtain computational estimates of actual gas deliveries over given time spans and to estimate their difference from corresponding values reported by gas consumers. Such estimation is performed using a computational fluid dynamics simulator of gas flows in the gas distribution system of interest. Numerical monitoring of the discrepancy is based on a statement and numerical solution of identification problem of a physically proved gas dynamics mode of natural gas transmission through specified gas distribution networks. The identified mode parameters should have a minimum discrepancy with field measurements of gas transport at specified reference points of the simulated pipeline network.

scholarly journals Extracranial arteriovenous malformations: from bedside to bench

Mutagenesis ◽  
2019 ◽  
Author(s):  
Congzhen Qiao ◽  
Gresham T Richter ◽  
Weijun Pan ◽  
Yunbo Jin ◽  
Xiaoxi Lin
Keyword(s):  
Arteriovenous Malformations ◽  
Short Circuit ◽  
Vascular Anomaly ◽  
High Recurrence Rate ◽  
Medical Interventions ◽  
Lethal Complications ◽  
Underlying Mechanisms ◽  
Fast Flow ◽  
Insight Into ◽  
Huge Challenge

Abstract Arteriovenous malformation (AVM) is defined as a fast-flow vascular anomaly that shunts blood from arteries directly to veins. This short circuit of blood flow contributes to progressive expansion of draining veins, resulting in ischaemia, tissue deformation and in some severe cases, congestive heart failure. Various medical interventions have been employed to treat AVM, however, management of which remains a huge challenge because of its high recurrence rate and lethal complications. Thus, understanding the underlying mechanisms of AVM development and progression will help direct discovery and a potential cure. Here, we summarize current findings in the field of extracranial AVMs with the aim to provide insight into their aetiology and molecular influences, in the hope to pave the way for future treatment.

Basis of the New Criteria in ASME B31.8 for Prioritization and Repair of Mechanical Damage

2002 ◽  
Author(s):  
M. J. Rosenfeld ◽  
John W. Pepper ◽  
Keith Leewis
Keyword(s):  
Natural Gas ◽  
Safety Concern ◽  
Mechanical Damage ◽  
Operating Experience ◽  
Third Party ◽  
Detailed Review ◽  
Natural Gas Pipelines ◽  
Industry Research ◽  
Pipe Section ◽  
New Criteria

Mechanical damage in the form of dents has emerged as a key safety concern for pipelines. In response, ASME B31.8, with assistance from GTI, undertook a detailed review of industry research and operating experience with respect to various forms of mechanical damage. Revised criteria for prioritizing and effectively repairing damage in natural gas pipelines were developed based on the findings. The criteria address plain dents, third-party type damage, dents that affect weldments, dents affected by corrosion, and strain levels associated with deformation of the pipe section. This paper discusses the generalities of the scientific findings and basis for the changes to the Code.

scholarly journals Special Issue Editorial: Nanoparticles in the Atmosphere

Atmosphere ◽  
2020 ◽  
Vol 11 (1) ◽  
pp. 61
Author(s):  
Jorma Joutsensaari
Keyword(s):  
Current Knowledge ◽  
Field Measurements ◽  
Special Issue ◽  
Modelling Studies ◽  
Insight Into

The aim of this Special Issue was to gain insight into the current knowledge on nanoparticles in the atmosphere, from laboratory and field measurements to theoretical and modelling studies of nanoparticles from various atmospheric environments [...]

Development and Application of Electroluminescence Imaging for CdS/CdTe Characterization

2003 ◽  
Vol 763 ◽  
Author(s):  
Scott Feldman ◽  
Fred Seymour ◽  
Tim Ohno ◽  
Victor Kaydanov ◽  
Reuben Collins
Keyword(s):  
Short Circuit ◽  
Ccd Camera ◽  
Short Circuit Current ◽  
Processing Parameters ◽  
Carrier Injection ◽  
Spatially Resolved ◽  
Carrier Recombination ◽  
Recombination Lifetimes ◽  
Insight Into ◽  
Injection Rates

AbstractA technique for spatially resolved optical characterization of CdS/CdTe thin film solar cells has been developed using electroluminescence (EL). In EL, excess minority carriers are injected via forward biasing. Light produced in radiative carrier recombination is collected with a CCD camera. Because EL intensity depends upon radiative vs. non-radiative recombination lifetimes, EL provides insight into material quality.Spatial resolution is a key benefit of EL as it provides insight into the non-uniformities of polycrystalline CdTe. At high magnification the resolution is diffraction limited, but coarser measurements of up to several millimeters in range may also be made. Non-uniformities in emission have been observed throughout this range.Further benefits of EL as a characterization technique are as follows: EL probes the region of most interest, namely the CdTe near the main junction. Also, it is observable at room temperature and data acquisition is fast. Finally, EL is observable at very low carrier injection rates, comparable to short circuit current. (Though more structure is often revealed at higher injection rates.) This low injection means that EL can be a non-destructive probe. This fact, along with the aforementioned ease of observation, means that EL could possibly be used for quality control and in situ testing of modules.Data gathered from CdS/CdTe cells from various institutions deposited using different methods such as close spaced sublimation, vapor transport, and sputtering are presented. In addition to changes in deposition technique, changes in processing parameters were observed to affect EL emission. Furthermore, overall EL emission decreased noticeably with stress at various biases and elevated temperature, with non-uniformity increasing in many cases. Changes in EL become apparent before changes in parameters acquired with standard current-voltage measurements, suggesting that this technique can be used as an early indicator for degrading cells. Finally, some dramatic changes in EL with stress suggest highly non-uniform degradation of the back contact.

On Pipe Elbow Elements in ABAQUS and Benchmark Tests

2014 ◽  
Author(s):  
Lingfu Zeng ◽  
Lennart G. Jansson ◽  
Yordan Venev
Keyword(s):  
Peak Stress ◽  
Coarse Mesh ◽  
Pipe Bend ◽  
Shell Elements ◽  
Finite Element Software ◽  
Pipe Elbow ◽  
Element Size ◽  
Benchmark Tests ◽  
Pipe Section ◽  
Insight Into

In this paper, elbow elements in commercial finite element software ABAQUS are reviewed and two commonly used elements, ELBOW31 (2-node, linear) and ELBOW32 (3-node, quadratic), are numerically tested for two Benchmark examples: a cantilever pipe and an in-plane bending pipe bend. Two main issues are studied through the numerical tests: (1) The effect of the element size and the number of ovalization modes chosen for computation; (2) The accuracy of computed deformation and stresses. To gain an insight into the behavior of these elements, a comparison against published results by experiment and computations using elbow elements in software ADINA and MARC, as well as computations using ABAQUS shell elements, is conducted. It is shown that: (i) these elements predict a good peak stress solution with a reasonably coarse mesh and 6 ovalization modes; (ii) the ovalization and the distribution of stresses predicted around the pipe section show, though using a relatively dense mesh, a notable difference as compared to solutions computed by ABAQUS shell elements; (iii) the ADINA elbow element seems to provide, though using a very coarse mesh, a solution closest to analytic and experimental results. It is concluded that there are great needs for in-depth studies on elbow elements regarding reliability and accuracy issues.

scholarly journals Planar to Trench: Short Circuit Capability Analysis of 1.2 kV SiC MOSFETs

2018 ◽  
Vol 924 ◽  
pp. 782-785 ◽  
Author(s):  
Bhagyalakshmi Kakarla ◽  
Thomas Ziemann ◽  
Selamnesh Nida ◽  
Elias Doenni ◽  
Ulrike Grossner
Keyword(s):  
Room Temperature ◽  
Field Effect Transistor ◽  
State Of The Art ◽  
Short Circuit ◽  
Metal Oxide Semiconductor ◽  
Operating Conditions ◽  
Oxide Semiconductor ◽  
Capability Analysis ◽  
Effect Transistor ◽  
Insight Into

This paper presents an insight into the short circuit (SC) capability of Rohm’s discrete 1.2 kV, 80 mΩ state-of-the-art silicon carbide (SiC) double trench metal-oxide-semiconductor field effect transistor (MOSFET). SC measurements are performed to compare the behavior of Wolfspeed’s similarly rated 1.2 kV, 80 mΩ planar MOSFET with the Rohm trench devices. Short circuit withstand time (SCWT) of both designs under nominal operating conditions at room temperature is measured by performing destructive SC tests.

Apparatus for Testing Drag Reducing Agents in Gas Transmission Pipelines

2016 ◽  
Author(s):  
Jianlei Chen ◽  
Wei Zhao ◽  
Yan Di ◽  
Banglong Jia ◽  
Jianbo Wang ◽  
...  
Keyword(s):  
Natural Gas ◽  
Performance Test ◽  
Test System ◽  
Gas Pipeline ◽  
Injection System ◽  
Pipe Surface ◽  
Pumping System ◽  
Operation Conditions ◽  
Pipe Section ◽  
Transmission Pipelines

Drag reduction agents (DRA) with its special properties adhering to the inner wall of gas pipeline can reduce the pipe surface roughness and turbulent velocity of gas flow. Injecting DRA into the natural gas pipeline is a potential and economical method which decreases the energy consumption and enhances gas delivery throughput. The premise that DRA can be used on site is to pass the performance test in laboratory, so reasonable DRA test system are designed through simulating the operation conditions of natural gas transmission pipelines. Emphatically improving the pumping system, atomization injection system and test pipe section. The pumping system adopts separation design pattern which can avoid various DRA samples blending drastically. The atomization injection system provides full atomized space for DRA solution which can ensure atomization injection process to carry out ideally. The test pipe section can replace quickly and ensure a higher measuring accuracy. The proposed approach above can perfect the test system for DRA used in gas transmission pipeline and can provide important guidance to the industrialized application of DRA.

Application of Noncircular Primary-Air Inlet Geometries in the Inshot Burners of Residential Gas Furnaces

1996 ◽  
Vol 118 (1) ◽  
pp. 58-64 ◽  
Author(s):  
P. Kolluri ◽  
A. Kamal ◽  
S. R. Gollahalli
Keyword(s):  
Temperature Field ◽  
Natural Gas ◽  
Combustion Chamber ◽  
Field Measurements ◽  
Air Entrainment ◽  
Combustion Products ◽  
Nox Emission ◽  
Air Inlet ◽  
Emission Index

Experiments with an inshot burner used in residential natural gas furnaces are presented. The concentrations of NOx, NO, and CO in the combustion products of partially aerated natural gas flames were measured in a laboratory combustion chamber. When the conventional circular venturi inlet of the inshot burner was replaced by elliptic venturi inlets, an increase of up to 30 percent in the primary-air entrainment and a decrease of up to 20 percent in the NOx emission index were observed. Temperature field measurements in the flames were in conformity with the emission index measurements.

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