45 research outputs found

    Wind Impact Assessment of a Sour Gas Release in an Offshore Platform

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    Complex installations that involve dangerous substances, such as oil and gas or nuclear plants, must mandatorily undergo a quantitative risk assessment (QRA) according to current regulations. This requires, among others, the simulation of hundreds of accidental scenarios, which are typically carried out using empirical tools due to their fast response. Nonetheless, since they are not able to guarantee sufficient accuracy, especially when complex geometries are involved, computational fluid dynamics (CFD) tools are increasingly used. In this work, a high-pressure accidental release of a sour gas (CH4-H2S) in an offshore platform under several wind conditions is considered. A methodology used to perform a wind sensitivity analysis via CFD, while avoiding high computational costs, is presented. The wind intensity impact on some risk-related figures of merit, such as the high lethality or irreversible injuries areas, is discussed in relation to the flammability and toxicity limits of the released mixture. The results show that even a very low amount of H2S in the released mixture can strongly affect the threat zones. A progressive decrease in the toxic and flammable volumes in the platform is observed as the wind velocity increases; nonetheless, a saturation effect appears in high wind speed scenarios

    Life Cycle Assessment (LCA) of MWool® Recycled Wool Fibers

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    Textile industries are in the spotlight due to the heavy environmental impacts along their products’ life cycle and, at the same time, they are a priority sector in the new circular economy action plan of the European Commission. In this framework, the Italian company Manteco SpA has developed a value chain based on the recycling of pre-and post-consumer discarded textiles, wh0se output is a secondary wool fiber named MWool® . This study develops an environmental analysis of recycled wool fibers through the Life Cycle Assessment (LCA) methodology, mainly using primary data. A parallel LCA is developed of virgin wool fiber, mostly based on literature data. Sensitivity analyses have been carried out: (i) to capture the uncertainty associated with virgin fibers’ impacts and (ii) to evaluate how MWool® impacts vary according to the origin and treatment of recycled textiles. Finally, the Circular Footprint Formula (CFF) has been applied to consider also a possible decay in quality typically affecting recycled fibers. Results show that recycled wool fibers have significantly lower environmental impacts than virgin fibers, even when the most unfavorable scenarios are considered. As climate change is concerned, 1 kg of MWool® has a carbon footprint of 0.1–0.9 kg CO2 eq., while producing virgin fibers releases 10–103 kg CO2 eq. Using the CFF, it emerges that recycled wool fibers can save about 60% of the impacts of virgin fibers. This study contributes to filling data gaps regarding LCAs applied to the textile sector, which is more and more in the spotlight and needs to address these environmental issues

    Value of a short non-contrast CMR protocol in MINOCA

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    ObjectivesTo evaluate the diagnostic performance of a short non-contrast CMR (ShtCMR) protocol relative to a matched standard comprehensive CMR (StdCMR) protocol in patients with myocardial infarction with non-obstructive coronary arteries (MINOCA).MethodsThis multicenter retrospective study included patients with a working diagnosis of MINOCA who underwent a StdCMR between January 2019 and December 2020. An expert and a non-expert reader performed a blinded reading with the ShtCMR (long-axis cine images, T2w-STIR, T1- and T2-mapping). A consensus reading of the StdCMR (reference standard) was performed at least 3 months after the ShtCMR reading session. Readers were asked to report the following: (1) diagnosis; (2) level of confidence in their diagnosis with the ShtCMR; (3) number of myocardial segments involved, and (4) functional parameters.ResultsA total of 179 patients were enrolled. The ShtCMR lasted 21 & PLUSMN; 9 min and the StdCMR 45 & PLUSMN; 11 min (p < 0.0001). ShtCMR allowed reaching the same diagnosis as StdCMR in 85% of patients when interpreted by expert readers (rising from 66% for poor confidence to 99% for good, p = 0.0001) and in 73% (p = 0.01) by non-expert ones (60% for poor vs 89% for good confidence, p = 0.0001). Overall, the ShtCMR overestimated the ejection fraction, underestimated cardiac volumes (p < 0.01), and underestimated the number of segments involved by pathology (p = 0.0008) when compared with the StdCMR.ConclusionThe ShtCMR was found to be a debatable alternative to the StdCMR in patients with MINOCA. Nevertheless, when an experienced reader reaches a good or very good diagnostic confidence using the ShtCMR, the reader may choose to stop the examination, reducing the length of the CMR without affecting the patient's diagnosis

    How underground systems can contribute to meet the challenges of energy transition

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    The paper provides an overview of the several scientific and technical issues and challenges to be addressed for underground storage of carbon dioxide, hydrogen and mixtures of hydrogen and natural gas. The experience gained on underground energy systems and materials is complemented by new competences to adequately respond to the new needs raised by transition from fossil fuels to renewables. The experimental characterization and modeling of geological formations (including geochemical and microbiological issues), fluids and fluid-flow behavior and mutual interactions of all the systems components at the thermodynamic conditions typical of underground systems as well as the assessment and monitoring of safety conditions of surface facilities and infrastructures require a deeply integrated teamwork and fit-for-purpose laboratories to support theoretical research. The group dealing with large-scale underground energy storage systems of Politecnico di Torino has joined forces with the researchers of the Center for Sustainable Future Technologies of the Italian Institute of Technology, also based in Torino, to meet these new challenges of the energy transition era, and evidence of the ongoing investigations is provided in this paper

    Geopolitical instability in Ukraine and security of energy supply. The effects on natural gas supply to Italy under different scenarios

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    The Italian energy system is characterised by a high level of import dependency, especially regarding natural gas supply. A dominant role in the NG imports is played by Russia, that in 2013 accounted for 43.6% of the total. As a consequence, the political and institutional crisis between Russia and Ukraine could have significant effects on the energy supply to Italy. In order to analyse these effects, a forecasting scenario analysis was performed by using the TIMES-based optimization model developed under the 7th Framework Programme REACCESS, able to fully represent the energy corridors (both captive and open sea) supplying the European Union and to evaluate, in a quantitative manner, the risk related to each supply. The analysis was focused on the consequences of a disruption in the supply through the Dolina physical natural gas hub (located in Ukraine) by means of two scenarios: one considering the closure of the hub from 2015 and the other describing a 50% NG flow reduction through it in 2015. The assumed time horizon was 2010-2040, and the effects on the supply composition, on the total system costs, on the marginal costs of natural gas and on the CO2 emissions level were investigated. The results show that the unavailability of the Dolina physical hub causes more significant effects on the mid-long term supply composition than the reduction of the NG flows through it in 2015. In particular, a strong reduction of the Russian contribution in comparison with the baseline one, a simultaneous increase of the import of LNG from Qatar and a decrease in the total amount of the NG supply by corridors, due to a fuel shift phenomenon, can be noticed. In the same way, the Dolina closure scenario leads to major negative effects also from the economical and environmental point of view. This study highlights the main problems of a high import dependency from a major supplier (as in the case of natural gas imports from Russia to Italy, but the modelling tool allows for the assessment of any EU country security of supply) and underlines the need of a strong diversification in the supply composition
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