Hydrogen jet-fire: Accident investigation and implementation of safety measures for the design of a downstream oil plant

As amply known, hydrogen plays a very significant role in the process industry exerting a vital functionality in oil refineries, namely for secondary level refining units such hydro-treating and hydrocracking sections. This paper starts from a statistical analysis on hydrogen accidents and a thorough investigation on the sequence and causes of an accident involving a hydrogen leakage in a downstream oil industry. We present some key features of the accident and comment some practical implications for setting up risk reduction options at the plant level. The applicative phase of the paper states the main prevention strategies and suggest possible mitigation measures for hydrogen leaks events, discussing some practical solutions applied in the design of a large refinery. The experience and lessons learned gained from the event investigation and the comparison of the accident with the predictions of the safety report leads to the formulation of proposals and design modifications aiming at preventing or at least minimizing the consequences

A novel index based framework for assessing hazards of toxic and flammable gaseous releases in process plants

Generally speaking, chemicals are the main source of fire, explosion and toxicity hazards. Notwithstanding technological development, enforcement of ATEX Directives and safety management system application, hazardous releases and following toxic dispersion or explosions in the process sector still claim lives and severe economic losses. Additionally, rather moderate releases of hazardous gases under semi-confined geometry are known to present a serious risk so that there is a need in the assessment of the maximum admissible gas build-up, in connection with adverse effects. For purpose of providing comprehensive warning of the hazardous nature of the considered gas and obtaining a simplified tool, we present a simple unified approach which, starting from the chemical-physical and hazardous properties of the released gas allows estimating both asphyxiation, fire/explosion and toxic exposure hazards

Generalized mathematical modelling of spray barriers

In this paper, experimental and theoretical investigations on liquid spray curtains are presented, in the context of absorbing and dispersing hazardous gaseous releases. The problem of release mitigation by absorption, either in pure water or in aqueous solution, was investigated or analytically solved by developing a general approach. The structure of the model includes a fluid-dynamic model describing air entrainment rate both in still air and in windy conditions, an absorption model, predicting spray efficiency and a mixing-dispersion model for the evaluation of the overall barrier effectiveness in environmental control. The model was validated by means of replicated experimental runs in a wind tunnel equipped with spray nozzles suitable to create a two-blade barrier. The model agreement with experimental data was fairly good in both cases of water and reacting curtain, which is promising for short-cut design purposes. The developed framework can be applied to more complex situations and different gas, allowing, as well, the attainment of a more generalized approach for the design of a curtain, once given the release parameters, the site layout and the sensitive target specifications

Atmospheric emissions from a fossil fuel power station: Dispersion modelling and experimental comparison

In this paper, a comparative study of different dispersion models considering stack emissions from a coalfired power plant. Modelling comparison study was performed utilizing Safe-Air II, a reliable Lagrangian model and ADMS 5adopting a skewed Gaussian representation. Fallouts were estimated starting from the statistical elaboration of meteorological data of the year 2012.Results evidenced a satisfactory agreement with measured data from monitoring stations, both in the discrete values and in the monthly and hourly averages. Furthermore, within an impact radius 40 km from the source, the areas of highest and lowest fallouts were identified in order to explore the possibility of considering lichens as potential bio-monitors, being well established their sensitivity to SO2 and eventual damage to the thalli

Development of a theoretical framework for the evaluation of risk connected to accidental oxygen releases

A short-cut methodology for a fast estimation of hazard from oxygen releases and the evaluation of safety distances is presented. Starting from a historical survey on accidents involving oxygen releases and consequent scenarios, the approach includes analytical models for the quantification of incremental hazards due to oxygen releases, in non-obstructed areas, both for continuous and nearly instantaneous scenarios, adopting a simple Gaussian dispersion model. An example of the application of the model in a real case-study and relevant quantitative results are presented

An analytical model of carbon dioxide jet from pressurized systems for safety distance evaluation

Normative legislations relating to standards and international guidelines within the framework of carbon capture sequestration (CCS) and the transport of carbon dioxide in the actual operating conditions are still under development. The focus of the present study is the cold jet modelling, including the orientation factor, representing a scenario still partially unexplored. The framework provides by simple analytical formulae the boundaries of the jet region and air entrainment behaviour, as well as the resulting ground level hazardous concentrations to humans. The model relies on a first experimental validation of the jet phase, evidencing that the model can be applied, at least as a first cautious screening tool, for safety distance evaluation

Changes in surgicaL behaviOrs dUring the CoviD-19 pandemic. The SICE CLOUD19 Study

BACKGROUND: The spread of the SARS-CoV2 virus, which causes COVID-19 disease, profoundly impacted the surgical community. Recommendations have been published to manage patients needing surgery during the COVID-19 pandemic. This survey, under the aegis of the Italian Society of Endoscopic Surgery, aims to analyze how Italian surgeons have changed their practice during the pandemic.METHODS: The authors designed an online survey that was circulated for completion to the Italian departments of general surgery registered in the Italian Ministry of Health database in December 2020. Questions were divided into three sections: hospital organization, screening policies, and safety profile of the surgical operation. The investigation periods were divided into the Italian pandemic phases I (March-May 2020), II (June-September 2020), and III (October-December 2020).RESULTS: Of 447 invited departments, 226 answered the survey. Most hospitals were treating both COVID-19-positive and -negative patients. The reduction in effective beds dedicated to surgical activity was significant, affecting 59% of the responding units. 12.4% of the respondents in phase I, 2.6% in phase II, and 7.7% in phase III reported that their surgical unit had been closed. 51.4%, 23.5%, and 47.8% of the respondents had at least one colleague reassigned to non-surgical COVID-19 activities during the three phases. There has been a reduction in elective (>200 procedures: 2.1%, 20.6% and 9.9% in the three phases, respectively) and emergency (<20 procedures: 43.3%, 27.1%, 36.5% in the three phases, respectively) surgical activity. The use of laparoscopy also had a setback in phase I (25.8% performed less than 20% of elective procedures through laparoscopy). 60.6% of the respondents used a smoke evacuation device during laparoscopy in phase I, 61.6% in phase II, and 64.2% in phase III. Almost all responders (82.8% vs. 93.2% vs. 92.7%) in each analyzed period did not modify or reduce the use of high-energy devices.CONCLUSION: This survey offers three faithful snapshots of how the surgical community has reacted to the COVID-19 pandemic during its three phases. The significant reduction in surgical activity indicates that better health policies and more evidence-based guidelines are needed to make up for lost time and surgery not performed during the pandemic

Risk of Guillain-Barr\ue9 syndrome after 2010-2011 influenza vaccination

Influenza vaccination has been implicated in Guillain Barr\ue9 Syndrome (GBS) although the evidence for this link is controversial. A case-control study was conducted between October 2010 and May 2011 in seven Italian Regions to explore the relation between influenza vaccination and GBS. The study included 176 GBS incident cases aged 6518 years from 86 neurological centers. Controls were selected among patients admitted for acute conditions to the Emergency Department of the same hospital as cases. Each control was matched to a case by sex, age, Region and admission date. Two different analyses were conducted: a matched case-control analysis and a self-controlled case series analysis (SCCS). Case-control analysis included 140 cases matched to 308 controls. The adjusted matched odds ratio (OR) for GBS occurrence within 6 weeks after influenza vaccination was 3.8 (95 % CI: 1.3, 10.5). A much stronger association with gastrointestinal infections (OR = 23.8; 95 % CI 7.3, 77.6) and influenza-like illness or upper respiratory tract infections (OR = 11.5; 95 % CI 5.6, 23.5) was highlighted. The SCCS analysis included all 176 GBS cases. Influenza vaccination was associated with GBS, with a relative risk of 2.1 (95 % CI 1.1, 3.9). According to these results the attributable risk in adults ranges from two to five GBS cases per 1,000,000 vaccinations

IER-SICH Nomogram to Predict Symptomatic Intracerebral Hemorrhage After Thrombectomy for Stroke

Background and Purpose - As a reliable scoring system to detect the risk of symptomatic intracerebral hemorrhage after thrombectomy for ischemic stroke is not yet available, we developed a nomogram for predicting symptomatic intracerebral hemorrhage in patients with large vessel occlusion in the anterior circulation who received bridging of thrombectomy with intravenous thrombolysis (training set), and to validate the model by using a cohort of patients treated with direct thrombectomy (test set). Methods - We conducted a cohort study on prospectively collected data from 3714 patients enrolled in the IER (Italian Registry of Endovascular Stroke Treatment in Acute Stroke). Symptomatic intracerebral hemorrhage was defined as any type of intracerebral hemorrhage with increase of 654 National Institutes of Health Stroke Scale score points from baseline 6424 hours or death. Based on multivariate logistic models, the nomogram was generated. We assessed the discriminative performance by using the area under the receiver operating characteristic curve. Results - National Institutes of Health Stroke Scale score, onset-to-end procedure time, age, unsuccessful recanalization, and Careggi collateral score composed the IER-SICH nomogram. After removing Careggi collateral score from the first model, a second model including Alberta Stroke Program Early CT Score was developed. The area under the receiver operating characteristic curve of the IER-SICH nomogram was 0.778 in the training set (n=492) and 0.709 in the test set (n=399). The area under the receiver operating characteristic curve of the second model was 0.733 in the training set (n=988) and 0.685 in the test set (n=779). Conclusions - The IER-SICH nomogram is the first model developed and validated for predicting symptomatic intracerebral hemorrhage after thrombectomy. It may provide indications on early identification of patients for more or less postprocedural intensive management