1,721,005 research outputs found
From a survey on accidents in the downstream oil industry to the development of a detailed near-miss reporting system
No full textA historical analysis with statistical investigation on accidental events in the oil industry from the beginning of the XX century till now, was performed in order to identify historical trend and go deeper into accident causes. The classification
methodology was developed referring to three headings, namely plant/process, environment and organization
and trying to go deeper into the analysis of the causes of the accidents reported and understand more of what is probably
behind the accidents. The accident types and severity were studied, plotting the accumulated frequency–fatality
curve for each item. In the subsequent applicative phase, we applied a similar classification approach to near-misses
directly collected over nine years observation in a large downstream oil firm. The historical analysis was extended
on each section of the refinery, paying a careful attention to all causes and consequences of the event. Data were
structured for analyzing trends and identifying possible precursors of unwanted events. According to the step-bystep
approach we try to evidence how immediate causes of a near-miss could be linked in some kind of causal chain
to underlying causes that should be controlled by middle or higher management, or are part of the corporate safety
culture
Learning from accidents: dinamica infortunistica e fattori determinanti nell’industria italiana
No full textRuolo della Simulazione discreta e stocastica, nella risoluzione di problemi primari multi settoriali: concettualizzazione, ricerca e sviluppo di applicazioni derivate dalle più innovative Tecnologie offerte dalla quarta Rivoluzione Industriale
No full textMetodologie di sviluppo ed analisi di modelli discreti e continui per la simulazione di sistemi.
Strumenti e problemi di analisi numerica; sviluppo di simulatori e federazioni di simulatori per
sistemi complessi. Definizione obiettivi, formalizzazione, soluzioni di implementazione,
integrazione, verifica, convalida, test, accreditamento ed esecuzione di modelli real-time, fasttime
e slow time.
La cosiddetta Rivoluzione Industriale 4.0, iniziata in Germania nel 2013 e di lì estesasi ad
altri Paesi industrializzati, Italia inclusa, grazie ai massicci finanziamenti dedicati alle Imprese per
ridare loro competitività sul piano internazionale, ha come punto centrale il dialogo diretto tra le
macchine, lungo l’intera catena logistica (fornitori, fabbrica, utenti finali), tramite l’uso di
opportuni sistemi informatici hardware e software. Il documento redatto dal MISE per le industrie
del nostro Paese, tra gli strumenti software riconosciuti come specifici indica i simulatori on-line.
Questo particolare tipo di modellizzazione è stato creato, come rilevabile dalla letteratura, dai
Professori Roberto Mosca e Pietro Giribone a metà degli anni ’80 per risolvere alcuni importanti
problemi che Aziende italiane quali Comau e Mandelli, leader mondiale nei cosiddetti sistemi
flessibili di produzione, non erano riusciti a risolvere con le tecnologie tradizionali.
Obiettivo della tesi di dottorato proposta è quella, sfruttando i rilevanti progressi evidenziatisi
negli ultimi vent’anni sia dall’elettronica dedicata che dagli elaboratori, di rilanciare la
metodologia della simulazione on-line real-time come elemento concettuale di alto livello,
rendendolo indispensabile per massimizzare i risultati ottenibili dalla già menzionata Rivoluzione
4.0.
Ciò potrà avvenire attraverso un interfacciamento accurato e ad alta velocità tra linee di
produzione, sistema logistico integrato, etc e i calcolatori addetti alla sorveglianza/ gestione di
questi elementi.
Sfruttando quindi a step di tempo predeterminato, la capacità previsionale dello strumento
simulativo, sarà possibile fare ripetutamente proiezioni sul rispetto dei tempi di produzione e/o
di apportare i cambiamenti di programmazione indispensabili per minimizzare il danno aziendale
nel caso di imprevisti, guasti accidentali, variazioni repentine del mix di produzione, etc.
L’uso di opportuni algoritmi, studiati caso per caso, potrà consentire all’elaboratore di prendere
decisioni in totale autonomia entro limiti prefissati o di passare il governo del processo
decisionale al responsabile di linea in tutti gli altri casi. Le diverse alternative decisionali potranno
essere valutate dal decisore sulla base di ulteriori lanci previsionali effettuati su un simulatore offline.The so-called 4.0 Industrial Revolution, which began in Germany in 2013 and extended from there to
other industrialized countries, including Italy, thanks to the massive loans dedicated to companies for
to restore their competitiveness on an international level, has as its central point the direct dialogue between the
machines, along the entire logistics chain (suppliers, factory, end users), through the use of
appropriate computer hardware and software systems. The document drawn up by the MISE for industries
of our country, among the software tools recognized as specific indicates the online simulators.
This particular type of modeling was created, as detectable by the literature, by
Professors Roberto Mosca and Pietro Giribone in the mid-1980s to solve some important ones
problems that Italian companies such as Comau and Mandelli, world leaders in so-called systems
flexible production, they had failed to solve with traditional technologies.
The objective of the proposed doctoral thesis is that, taking advantage of the significant progress highlighted
in the last twenty years both from dedicated electronics and from computers, to relaunch the
real-time online simulation methodology as a high-level conceptual element,
making it indispensable to maximize the results obtainable from the aforementioned Revolution
4.0
Mathematical modelling of fluid spray curtains to mitigate accidental releases
No full textIn this article experimental and theoretical investigations on liquid spray curtains are presented, in the context of absorbing and dispersing accidental releases of chlorine in air. A mathematical model of a two-phase jet is developed to evaluate the entrained air rate in connection with the liquid flow rate. The model was successfully compared by means of replicated wind tunnel experimental runs adopting spray nozzles suitable to create a two-blade barrier. The experimental work demonstrated that it is possible to distinguish two regions in the barrier. One region is dominated by the liquid inertia and is comparable to an airplane jet. The other region is dominated by gravitational effects, and its dimensions do not vary appreciably. An analytical solution to the problem is obtained, taking into account the instantaneous and nonreversible chemical reactions, i.e., chlorine absorption in alkaline solutions, in the case of still air. The developed methodology could be applied to more complex situations, allowing the attainment of a more generalized approach for the design of a curtain given the release parameters, the site layout, and vulnerable target specifications
A critical approach to safety equipment and emergency time evaluation based on actual information from the Bhopal gas tragedy
No full textAs amply reported, after Bhopal disaster process safety got a boost worldwide and risk analysis got applied more generally. Even if the concept of inherent safety, strongly promoted by Trevor Kletz, represents one of the main lessons from this tragedy, in the first part of the paper we focus on Bhopal mitigation measures representing the ultimate relevant layer of protection. Starting from a technical analysis of the whole safety equipment of the plant and relevant empirical evidences, we face the short-cut design of critical safety devices suitable to mitigate release effects. The applied method allows a preliminary design and management tool to evaluate the effectiveness of safety systems and the impact on surroundings. In the second part, we develop an empirical-based framework allowing to identify emergency actions and intervention time and demonstrate how the implementation of these safety measures when reaching a critical pressure of 10 psig in Tank 610, even under the condition of protective equipment out of commission, would have surely mitigated such a high profile tragedy. The paper illustrates the determining contribution to this tragedy of such deficiencies in the safety procedures for handling abnormal situations and emergencies by the company
A theoretical approach to risk evaluation in connection with oxygen releases
No full textOxygen–enriched combustion offers several advantages, including higher combustion efficiency and higher CO2 concentration in the flue gas, allowing an easier and cheaper CO2 separation from the gas itself. In addition, oxygen combustion is considered in the IPCC list as a category
of CCS options for large point source emitters. Oxygen enriched process can be adopted to enhance sulphur recovery in the effluent stream adopting modified Claus processes in refineries. According to international historical data, accidents involving gas pipelines still happen and often result in severe consequences. This implies that measures need to be adopted in order to adequately quantify and thereby to mitigate the risks. In relative terms, the problem of HazMat pipeline risk assessment does not come with hazard analysis, or the estimation of failure frequency, but with the calculation of the consequences. In this paper, we consider the peculiar case of oxygen instantaneous or continuous releases from a pipeline and consequent evolving scenarios. A novel modelling approach to risk evaluation is elaborated starting from the rather common situation of a pipe-way where several gas/liquid lines are localized, in a rather congested industrial area. As an applicative case-study, it is considered a downstream oil industry where
the possibility of replacing the air feeding to Claus plant with oxygen enriched line is investigated, with the aim of enhancing sulphur recovery yield. This technical option from one side can be seen as an approach to process intensification, from the other side poses obvious safety issues
A study on road tunnel fires using hazmat, with emphasis on critical ventilation velocity
No full textOne of the main protective measures to be adopted in case of fires in road/rail tunnels is represented by suitable longitudinal ventilation systems being able to avoid fire and smoke exposure of humans, and to create a safe route upstream for evacuation. The key design parameter is the so-called critical ventilation velocity, i.e. the minimum speed of the longitudinal ventilation avoiding the spread of the smoke produced by fire in the upstream direction, known as ‘backlayering’. In several studies, the critical velocity was correlated to the fire heat release rate on the basis of semi-empirical models, already adopted in describing nonconfined fires. However, experimental runs both on a laboratory scale and on a real scale, evidenced that such correlations are valid only in connection with fires of limited extent, while at high rates of heat release and when the flame height reaches the tunnel ceiling, the critical velocity can tend asymptotically to a maximum value vca. In this study, reference was made to the worst scenario of hydrocarbon pool fire extended to the whole tunnel section. The main hypotheses the model is based upon are uniform distribution of chemico-physical properties of fire and smoke along the considered transverse section of the tunnel. The evaluation of the critical velocity is performed by solving mass, momentum and energy balances obtained considering possible dynamic interactions among the different fluxes (backlayering, air, flame/smoke column). In particular, the inertial action exerted by fresh air on backlayering was determined on the basis of the experimental results. The asymptotic value of the critical velocity resulting by mathematical modelling is in good agreement with those proposed by other authors, for example by means of complex CFD (computational fluid dynamics) studies. Moreover, the developed model is easily adaptable to the evaluation of vca, when dealing with geometrical conditions different from the ones studied here e.g., tunnel of different geometry, fire not extended to the whole section of the tunnel, obstacle presence in the tunnel, sloping tunnels
Investigation and analysis of a propane release and flash fire during a polymerisation reactor dumping
No full textA propane gas cloud was released into the atmosphere
when the bottom valve of a polymerisation tank was
opened to collect and remove spent powder. The
powder on the floor unexpectedly started evaporating
hydrocarbons, and a propane cloud drifted quickly
through the plant and ignited at the pump station area.
Although the flash fire was promptly extinguished, one
person was killed and several were injured. A detailed
investigation was carried out to define the sequences
and ìdentify the most likely causes of the accident.
Starting from the immediate cause, differerent sub steps
were identified as possibie underlying causes, in order to
identify possible deficiencies in the safety mariagement
system or safety culture of the company. Conclusions are
drawn about practical recommendations to improve safety
in dumping activities within a polymerisation plant. The
incident clearly shows how an effective HSE management
system could have prevented or minimised the occurrence
of such an unwanted event
Human factor and port safety after the container revolution: relationship between workplace, organizational factors and occupational injuries
No full textSeveral factors can affect occupational accident frequency, namely economical factors, technologies used (low automation, discontinuous operating) job design, organization of work/environmental conditions and human factors. In particular, technological advances in industrial activities can give rise to improvement in productivity and in occupational health and safety, but not necessarily simultaneously. The beginning of the container transport dates back to fifty years ago, but while containerisation changed everything, from ships and ports to patterns of global trade, its impact on work injuries was not explored at all. The aim of this paper is to investigate the relationship between work organization, job experience, productivity and occupational accidents, from the starting of the container expansion to nowadays, considering Genoa port (Italy), one of the largest of the Mediterranean Sea. In order to minimize possible reporting biases, such as underreporting or reclassification to a lower level of severity, injury statistics are elaborated starting from data collected directly on site, from internal accident or medical-aid reports. An in-depth statistical analysis on occupational injuries in the years 1980-2001 is carried out, with reference to frequency indexes, mechanism of injury and material causes. The increase of container-ships traffic and, consequently, the sharp change in port infrastructure involved a rapid modification also in the work organization, with particular reference to the number and characteristics of workforce (decrease from 5783 to nearly 1000 employees and increase of low experience workers from 28% to 74%). The striking high percentage increase of young or low experienced workers in handling container (and performing correlated new tasks) caused a remarkable increase of the risk for occupational injuries. In the studied port, we recorded an increase of the frequency index FI from 13.0 to 29.7. It results that the increased expansion of shipping container utilisation is not connected to a correspondent human factor safety implementation. We must notice that higher injury frequencies are associated to risk transfer (with the elimination of a specific hazard by transferring the risk to another task or another group of workers). Main risk factors are pointed out, revealing an increase of accidents due to transport vehicle (+8.3%) and a reduction of accidents caused by substance or materials (-4.5%). These factors show a statistical significative correlation with the new job tasks. Consideration of these findings may enable managerial solutions and workplace organization interventions for the prevention of injuries and safety performance improvement in port activities
Occupational injuries in Italy: risk factors and long term trend (1951-98)
No full textTrends in the rates of total injuries and fatal accidents in the different sectors of Italian industries were explored during the period 1951-98. Causes and dynamics of injury were also studied for setting priorities for improving safety standards
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