scholarly journals Quantification of Uncertainty in CFD Simulation of Accidental Gas Release for O & G Quantitative Risk Assessment

Energies ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 8117
Author(s):  
Fabrizio Pappalardo ◽  
Alberto Moscatello ◽  
Gianmario Ledda ◽  
Anna Chiara Uggenti ◽  
Raffaella Gerboni ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Cfd Simulation ◽  
Risk Measures ◽  
Quantitative Risk Assessment ◽  
Ansys Fluent ◽  
Cfd Models ◽  
Grid Convergence ◽  
Accident Simulation ◽  
Grid Convergence Index ◽  
Offshore Oil

Quantitative Risk Assessment (QRA) of Oil & Gas installations implies modeling accidents’ evolution. Computational Fluid Dynamics (CFD) is one way to do this, and off-the-shelf tools are available, such as FLACS developed by Gexcon US and KFX developed by DNV-GL. A recent model based on ANSYS Fluent, named SBAM (Source Box Accident Model) was proposed by the SEADOG lab at Politecnico di Torino. In this work, we address one major concern related to the use of CFD tools for accident simulation, which is the relevant computational demand that limits the number of simulations that can be performed. This brings with it the challenge of quantifying the uncertainty of the results obtained, which requires performing a large number of simulations. Here we propose a procedure for the Uncertainty Quantification (UQ) of FLACX, KFX and SBAM, and show its performance considering an accidental high-pressure methane release scenario in a realistic offshore Oil & Gas (O & G) platform deck. The novelty of the work is that the UQ of the CFD models, which is performed relying on well-consolidated approaches such as the Grid Convergence Index (GCI) method and a generalization of Richardson’s extrapolation, is originally propagated to a set of risk measures that can be used to support the decision-making process to prevent/mitigate accidental scenarios.

scholarly journals Risk evaluation in road tunnels based on CFD results

2021 ◽  
pp. 174-174
Author(s):  
Peter Vidmar
Keyword(s):  
Risk Assessment ◽  
Cfd Simulation ◽  
Physical Phenomenon ◽  
Professional Community ◽  
Quantitative Risk Assessment ◽  
Consequence Analysis ◽  
Tunnel Fire ◽  
Road Tunnels ◽  
Assessment Approach ◽  
Fast Processing

Approaches to risk assessment in tunnelling and underground spaces were introduced in 2004 as a result of several serious accidents in tunnels such as Mont Blanc and Tauern Tunnel in 1999. The EU has published the minimum safety requirements for tunnels over 500 m on Trans-European Road Network. The risk assessment is mandatory and should cover all components of the system, i.e. infrastructure, operation, users and vehicles. The professional community has started using the QRA (Quantitative Risk Assessment) approach, where the crucial issue is the consequence analysis of fire scenarios in a tunnel. Fire development is a complex physical phenomenon and its calculation is time consuming; therefore, complex models have rarely been used in QRA approaches. This paper presents the methodology of integrating fast-processing risk assessment methods with time-consuming CFD (Computational Fluid Dynamics) methods for fire consequence analysis in the process of tunnel safety assessment. The main variables are soot density and temperature, which are analysed in one-minute time steps during the fire. Human behaviour is considered with the evacuation model, which is needed to evaluate fatalities during the fire process. The application of the methodology is presented based on the evaluation of the national tolerable risk for tunnel transport and compared with referenced EU risk criteria. Furthermore, the presented methodology links CFD simulation results and the QRA approach, still representing the collective risk with F-N curves.

scholarly journals Application of quantitative risk assessment on offshore oil & gas industry

2014 ◽  
Vol 17 (3) ◽  
pp. 62-68
Author(s):  
Tin Trung Huynh ◽  
Vinh Trong Bui
Keyword(s):  
Risk Assessment ◽  
Quantitative Risk Assessment ◽  
Modern World ◽  
Engineering Project ◽  
Gas Industry ◽  
Production Platform ◽  
Management Approaches ◽  
The Uk ◽  
Offshore Oil ◽  
Oil Gas

Production of Oil & Gas in offshore involves some of the most ambitious engineering projects of the modern world, is a prime source of revenue for many countries. It is also involved risks of major accidents which have been demonstrated by disaster on the UK production platform Piper Alpha. Major accidents represent the ultimate, most disastrous way in which an offshore engineering project can go wrong. Accidents cause death, suffering, environmental pollution and disruption of business. To ensure all risks identified and controlled, risk management approaches need applying. This paper discusses the application of quantitative risk assessment approaches and its importance throughout the entire offshore installation.

Risk Assessment Study for a Floating, Production, Storage and Offloading Vessel (FPSO) in Deep Waters

2014 ◽  
Vol 700 ◽  
pp. 495-500
Author(s):  
Bruna C. de S. Lima ◽  
Lucas G. de Goes ◽  
Natália P.M. Silva ◽  
Paola C. Almeida ◽  
Erick B.F. Galante ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Oil And Gas ◽  
Gas Production ◽  
Quantitative Risk Assessment ◽  
Storage Unit ◽  
Oil And Gas Production ◽  
Deep Waters ◽  
Assessment Study ◽  
Offshore Oil And Gas ◽  
Offshore Oil

This paper presents a quantitative risk assessment study on a Floating, Production, Storage and Offloading Vessel that operate in Brazilian offshore oil and gas production waters. In particular a study of the risks applied to a Storage Unit and Transfer Oil, focusing on the physical, especially in operations involving storage and handling of flammable liquids. The results showed that the unit must take safety measures process, because a failure in the system can affect other units; the level of security for the population of the ship is within the acceptable.

The Effects of Corrosion Measurement Error on a Safety Risk Assessment: A TransGas Case Study

2014 ◽  
Author(s):  
Daryl Bandstra ◽  
Corey Gorrill
Keyword(s):  
Risk Assessment ◽  
Risk Measures ◽  
Quantitative Risk Assessment ◽  
Probability Models ◽  
Corrosion Failure ◽  
Safety Risk ◽  
Risk Levels ◽  
Transmission Pipeline ◽  
Operating Risk ◽  
The Impact

The risk of pipeline failure is a measure of the state of knowledge of the pipeline; improved knowledge of the pipeline reduces the uncertainty and therefore can reduce the associated risk. Specifically for corrosion defects, the knowledge of the number and size of defects is often obtained using in-line inspection tools which have uncertainty associated with their measurement capabilities. Quantitative Risk Assessment (QRA) is a methodology that objectively assesses a range of pipeline integrity threats including the threat of corrosion failure. QRA can incorporate the impact of significant sources of analysis uncertainty, such as feature sizing in risk estimates. This paper discusses an application of QRA used to evaluate the operating risk of high pressure transmission pipeline segments in the TransGas system. Specific examples are described in which the inspection tool sizing uncertainty was shown to exert a significant influence on the calculated risk levels. In carrying out the analysis, the failure probability models selected were dependent on the nature of the integrity threat and the type of information available for each pipeline. For the assessment of corrosion integrity, the results of in-line inspections were used directly in determining failure likelihood. For the other threats including equipment impact, geotechnical hazards, manufacturing cracks and stress corrosion cracking, the probability of failure was estimated from historical failure rates with adjustments to reflect line-specific conditions. Failure consequences were estimated using models that quantify the safety implications of loss of containment events. Using these models, safety risk measures were calculated along the length of each pipeline. The results of the analysis show the benefit of the use of inspection technologies with improved sizing accuracy, in terms of reduction in expected operating risk.

Impact of Inlet Boundary Conditions on the Fluid Distribution of Supply Duct

2016 ◽  
Vol 861 ◽  
pp. 384-391 ◽  
Author(s):  
Laszlo Czetany ◽  
Peter Lang
Keyword(s):  
Boundary Conditions ◽  
Cfd Simulation ◽  
Turbulent Pipe Flow ◽  
Fluid Distribution ◽  
Duct Flow ◽  
Special Flow ◽  
Grid Convergence ◽  
Grid Convergence Index ◽  
Comfort Parameters ◽  
The Impact

Ventilation is important to maintain the indoor air quality and other comfort parameters in the occupied zone. The design of ventilation systems is based on one dimensional approach. When the air distribution is modelled in the ventilated space usually CFD simulation is performed and simplified boundary conditions are defined at the locations where the supply air enters the room. However, in some cases it is difficult to predict the duct flow by 1D methods. The flow in the duct system determines the outflow at the air terminal devices. The interaction between the multiple system elements is important, since many different combinations are possible, for instance multiple bends can create a special flow field which also influences the distribution performance of the duct. It is very important to determine this impact, because the room airflow depends on it. In this study the impact of the inlet boundary conditions on the fluid distribution performance of a special supply duct –which is designed to provide uniform distribution– is investigated with CFD. Three different inlet boundary conditions are defined: constant inlet velocity and turbulence parameters estimated from intensity and hydraulic diameter, diffuser after fully developed turbulent pipe flow, diffuser with one bend and a Venturi-tube upstream. In each case, the simulations are performed with the realizable k-epsilon model. The reliability of the results is estimated with the grid convergence index.

A semi-quantitative risk assessment model for the outbreak of grass carp hemorrhage

2013 ◽  
Vol 19 (3) ◽  
pp. 521-527 ◽  
Author(s):  
Song YANG ◽  
Shuqin WU ◽  
Ningqiu LI ◽  
Cunbin SHI ◽  
Guocheng DENG ◽  
...  
Keyword(s):  
Risk Assessment ◽  
Grass Carp ◽  
Assessment Model ◽  
Quantitative Risk Assessment ◽  
Risk Assessment Model

Risk assessment of Campylobacter species in shellfish: identifying the unknown

1997 ◽  
Vol 35 (11-12) ◽  
pp. 29-34 ◽  
Author(s):  
P. Teunis ◽  
A. Havelaar ◽  
J. Vliegenthart ◽  
G. Roessink
Keyword(s):  
Risk Assessment ◽  
Quantitative Risk Assessment ◽  
Contamination Level ◽  
Risk Of Infection ◽  
Worst Case ◽  
Considerable Uncertainty ◽  
Risk Estimates ◽  
Consumption Data ◽  
Campylobacter Infection ◽  
Campylobacter Spp

Shellfish are frequently contaminated by Campylobacter spp, presumably originating from faeces from gulls feeding in the growing or relaying waters. The possible health effects of eating contaminated shellfish were estimated by quantitative risk assessment. A paucity of data was encountered necessitating many assumptions to complete the risk estimate. The level of Campylobacter spp in shellfish meat was calculated on the basis of a five-tube, single dilution MPN and was strongly season-dependent. The contamination level of mussels (<1/g) appeared to be higher than in oysters. The usual steaming process of mussels was found to completely inactivate Campylobacter spp so that risks are restricted to raw/undercooked shellfish. Consumption data were estimated on the basis of the usual size of a portion of raw shellfish and the weight of meat/individual animal. Using these data, season-dependent dose-distributions could be estimated. The dominant species in Dutch shellfish is C. lari but little is known on its infectivity for man. As a worst case assumption, it was assumed that the infectivity was similar to C. jejuni. A published dose-response model for Campylobacter-infection of volunteers is available but with considerable uncertainty in the low dose region. Using Monte Carlo simulation, risk estimates were constructed. The consumption of a single portion of raw shellfish resulted in a risk of infection of 5–20% for mussels (depending on season; 95% CI 0.01–60%). Repeated (e.g. monthly) exposures throughout a year resulted in an infection risk of 60% (95% CI 7–99%). Risks for oysters were slightly lower than for mussels. It can be concluded that, under the assumptions made, the risk of infection with Campylobacter spp by eating of raw shellfish is substantial. Quantitative risk estimates are highly demanding for the availability and quality of experimental data, and many research needs were identified.

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