查看更多>>摘要：The purpose of passive air blast safety valves is to protect people and technical installations in buildings or facilities. In case of explosions, e.g. due to technical failures in an oil- and gas refinery, the safety valve should close in milliseconds with the incident shock wave and substantially reduce the blast-pressure leakage into the building. On the other hand, the safety valve should exhibit a low pressure drop in normal operation in order to reduce the power consumption of the ventilators. One main difficulty in the design of such safety valves is to meet the minimum technical requirements, while ensuring the functionality in intrinsically different operating modes. Therefore, the present study proposes a target-oriented evaluation and optimization procedure for such devices, incorporating comprehensive numerical and experimental investigations. CFD, FEM and FSI analyses are regarded as an appropriate approach to predict valve performance parameters and to gain additional insights into the flow or structural behavior of the safety valve, which serves then as a basis for geometrical optimizations. The introduced procedure is exemplified on an existing passive air blast safety valve as a case study. The performance of the new design is significantly increased in ventilation operation, while meeting the performance criteria in the stress case when subjected to blast loads.
查看更多>>摘要：A vented corn starch dust explosion in an 11.5 m~3 vessel is studied using both experimental and numerical methods. The reduced explosion overpressure in the vessel is recorded using two pressure sensors mounted on the wall inside of the vessel. Unsteady three-dimensional Reynolds-Averaged Navier-Stokes simulations of the experiment are performed using the Flame Speed Closure (FSC) model of the influence of turbulence on premixed combustion. The model was thoroughly validated in previous studies and was earlier implemented into Open-FOAM CFD software. The self-acceleration of a large-scale flame kernel is associated with the influence of combustion-induced pressure perturbations on the flow of unburned reactants ahead of the kernel. Accordingly, the FSC model is extended by adapting the well-known experimental observations of the self-similarity of the kernel acceleration. Influence of different turbulence models on the simulated results is also explored. Thanks to the extension of the FSC model, the measured time-dependence of the pressure is well predicted when the k-omega-SST turbulence model is used.
查看更多>>摘要：This paper presents a tank farm safety assessment method based on the structure entropy weight method and cloud model. This method considers the natural fuzziness of safety and fluctuation in the safety level, which can not only provide the assessment index weights combined subjectively and objectively but also consider the fuzziness of the safety level boundary. Finally, this method can be used to obtain a scientific safety level to prevent accidents. In addition, taking the tank farms of four petroleum and petrochemical companies as examples, this safety assessment method is verified to be an effective tool for safety management.
Ronald ZinkeKevin WotheDmitry DugarevOliver Gotze...
10页
查看更多>>摘要：Major accidents in the process industry often lead to the release of light or dense gases, which can mean a thread to employees, local residents or to the environment. Possible scenarios are therefore analyzed and evaluated in advance for approval issues. There is a trend, where simple empirical models are being replaced with more complex numerical models. Gaussian dispersion models or models based on dimensional analysis approaches are for example, increasingly replaced by CFD simulations. The main reason for this is the potentially higher accuracy. However, usually scenarios using sharp parameter values are calculated, since comprehensive consideration of parameter distributions via Monte Carlo or Latin Hypercube Sampling fails due to the numerical effort. This includes the risk that the influence of uncertainties on the simulation results is not taken into account. Response surface methods offer an alternative, with which the CFD problem can be mapped onto an algebraic surrogate model. If this is sufficiently precise, parameter sampling can also be carried out with the surrogate as well, as shown in some publications. Previous investigations only demonstrated the basic principle using trivial dispersion models. In this paper two realistic CFD simulations from the plant safety area are considered: VOC emissions from a storage tank and near-ground dense gas emissions. The entire procedure of response surface determination and parameter studies was automated and parallelized for high-performance-computing, and is carried out on the underlying CFD grids. For the CFD simulations as well as for all visualizations, the commercial software ANSYS CFX and the open source software OpenFOAM were used. The aim of this paper is to demonstrate the method using industry-relevant applications as well as to show how this can be used in practical engineering applications. The quality of surrogate modeling, the numerical effort and advantages that can result from the procedure are discussed as well as advantages which may result from taking parameter uncertainties into account in safety studies.
Faluk Shair MustafaAdhban Omar Ahmad FareaRafi Ullah KhanJingbo Yin...
11页
查看更多>>摘要：Recently, hazardous cargo accidents such as those at Beirut and Tianjin ports have raised serious concerns over how high-risk cargoes should be handled. While the role of human error in such accidents is widely known, knowledge of how the related factors interact is less developed. To that end, the present study analyzed 352 hazardous cargo accidents occurring at ports between 1960 and 2018. A novel research framework, the Human Factors Analysis and Classification System for Port Environment Hazardous Cargo Accidents (HFACS-PEHCA) was developed for the analysis. The findings revealed that violations, limited intellect, inappropriate supervision, and an inadequate safety culture were the most prominent factors involved in hazardous cargo accidents. Correlations between these factors were established and the probabilities of five accident causation paths were calculated. The most likely way for a hazardous cargo accident to occur was via the path "Deficient safety culture → Inappropriate supervision → Limited Intellect → Violations." The study draws on these insights to propose safety procedures to mitigate the risk of accidents at ports dealing with hazardous cargo.
查看更多>>摘要：Modern chemical processes rely on distributed control systems to make the repetitive and routine adjustments to maintain steady operation. Operators are still required to "supervise the (system) supervisor" and intervene when variables exceed pre-programmed parameters to avert major incidents. Research in human-computer interaction and advanced process control has often focused on data-driven methods for fault detection as distinct from operator effectiveness. In this paper, we explore the application of a novel data-driven fault-detection technique to enhance operator decision support. During a simulated abnormal event, three users attempted to diagnose the root cause of a process upset using a traditional or standard interface, then with the addition of causal maps, in a A-B-A single-subject design. The causal maps were derived using a hierarchical method that could be applied to a wide range of chemical processes as an online, adaptive augmentation for abnormal situation management. Using a think-aloud technique, the three participants developed high quality insights into the process without negatively impacting the overall task load. These preliminary findings challenge prevailing wisdom in process control interface design, which often focuses on de-cluttering displays at the cost of information resolution.
查看更多>>摘要：Al-Ni mechanical alloys containing nickel are synthesized to explore the explosion hazard of fuel additives in energetic formulations in this study. Explosion severity and ignition sensitivity of Al and Al-Ni powders are measured. The results show that as the nickel content increases, the synthesizing heat of Ni-aluminide will firstly increase, and then decrease, which may also make the explosion severity of aluminum powder increase firstly and then decrease accordingly. The powder's sensitivity to electrostatic ignition will grow as the nickel content increases. As the nickel content increases from 0 to 17%, the average activation energy of Al-Ni powder decreases by 77.5%. The increase of ignition energy mainly affects the flame propagation, but with few effects on the process of Al-Ni combustion. Therefore, as the ignition energy increases, the explosion severity of the Al and Al-Ni powders decreases slightly. For safety's sake, the production and storage devices must be inert, and the concentration of oxygen should be less than 5%.
Alberto MoscatelloRaffaella GerboniGianmario LeddaAnna Chiara Uggenti...
10页
查看更多>>摘要：In this paper, the experimental validation of an innovative CFD approach, called SBAM ("Source Box Accidental Model"), is described. SBAM was developed in ANSYS Fluent and is aimed at a more efficient characterisation of accidental high-pressure gas releases in congested plants. The experimental setup, methodology and a preliminary CFD-experimental data comparison are described. The validation campaign has been carried out in the SEASTAR-WT wind tunnel, realized at the Environment Park in Turin (Italy). A 1:10 scaled Oil & Gas platform mockup, equipped with flow and gas concentration sensors, was built and installed inside the wind tunnel, in order to reproduce an accidental gaseous release in dynamic similarity conditions with the real cases. A set of gas releases were performed, and the predicted concentrations were compared to the observed ones in order to validate the CFD model. Several statistical measures with their range of acceptability allowed to compare the two sets of data. Results showed that, in most of the cases, acceptance criteria were met and a good consistency between experimental and numerical values is found. Furthermore, an overestimating tendency of SBAM is observed, suggesting that it is a conservative tool for consequences estimation.
Cengiz DirikDayang Radiah Awang BiakMus'ab Abdul RazakNik Nor Liyana Nik Ibrahim...
9页
查看更多>>摘要：This paper describes the failure assessment of the unloading arm unit that is connected to a Liquified Natural Gas (LNG) terminal. In this work, an external event, i.e., lightning, was simulated as the triggering event. A Temporal Fault Tree (TFT) analysis was developed, and sequential failures that function under the Priority AND (PAND) gate were assessed. The results show that the highest contributing factor to the failure of the terminal unloading arm was the sequential failure due to the loss of sensors which can happen before or after lightning strikes. The occurrence of failures for the loading arm was estimated using a Monte Carlo Simulation (MCS). For service years of 32.7, the sequential failures occurred 131 times when preventive maintenance was not considered. This work also presents that the failure distribution of the marine loading arm follows the Weibull distribution characteristic with the scale (α) and the shape (β) parameters values of 132,817.5 h~(-1) and 1.556, respectively.
查看更多>>摘要：Corrosion degradation is one of the main causations of natural gas pipeline failure, which poses a severe threat to human life, assets, and the environment. This paper develops a methodology to assess the risk of corrosioninduced natural gas pipeline accidents considering the uncertainties in incident escalations. This approach can capture both the uncertainties in corrosion failure likelihood and the impact of pipeline leak accidents. A pair of limit state functions are established to estimate the corrosion failure probability of the pipeline. The pipeline accident from gas release to vapor cloud explosion (VCE) is modelled using empirical models. Subsequently, the uncertainties in gas pipeline corrosion failure accidents, reflected by some uncertain parameters, e.g., basic pipeline parameters, corrosion defect and environmental conditions et al., are identified. These identified parameters are discretized and described using a set of probability density functions. Eventually, Monte Carlo (MC) method is utilized to solve the established models. Besides, sensitivity analysis is conducted to study the effect of uncertain parameters on the likelihood and impact of a pipeline accident. A practical case is used to test the methodology, proving a valuable tool for risk assessment of corrosion-induced natural gas pipeline accidents.
NSTL
Elsevier