1,287 research outputs found

    Industrial risk in the Lombardy Region (Italy): what people perceive and what are the gaps to improve the risk communication and the participatory processes

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    Risk communication is of vital importance in today\u2019s society, as audiences become ever more questioning about the causes and effects of risk. However, the communication of risk is a complex activity involving many different types of communicators and destinataries, from scientists, to the media, to government agencies, industry and consumer groups, each of which having its own agendas to fulfil. Such variation across the communication of the same risk can lead to confusion, misunderstandings, misreporting in the media and subsequent conflicts. The goal of risk communication is to produce an informed public. The personal nature of risk issues and the uncertainty associated with estimating risk can provoke considerable anxiety for the public and make adopted risk management strategies less acceptable. Lombardy is one of the most densely populated and industrialized regions in Europe and nearly 280 Seveso sites interest it. The Seveso Directive requires specific measures on risk communication to the population. Nevertheless, the Lombardy Region Authorities consider that the implementation of such provisions is too weak. Therefore an exploratory research has been concluded, in order to estimate the gaps in risk communication and to improve the participation of the population in the emergency preparedness activities. The paper reports the main results of the research and illustrates the potential strategies to improve the risk communication and the population participation and preparedness (\uc9upolis Lombardia 2011)

    Safe optimization of potentially runaway processes using topology based tools and software

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    In chemical industries, fast and strongly exothermic reactions are often to be carried out to synthesize a number of intermediates and final desired products. Such processes can exhibit a phenomenon known as \u201cthermal runaway\u201d that consists in a reactor temperature loss of control. During the course of the years, lots of methods, aimed to detect the set of operating parameters (e.g., dosing times, initial reactor temperature, coolant temperature, etc..) at which such a dangerous phenomenon can occur, have been developed. Moreover, in the last few years, the attention has been posed on safe process optimization, that is how to compute the set of operating parameters able to ensure high reactor productivity and, contextually, safe conditions. To achieve this goal, with particular reference to industrial semibatch synthesis carried out using both isothermal and isoperibolic temperature control mode, a dedicated optimization software has been implemented. Such a software identifies the optimum set of operating parameters using a topological criterion able to bind the so-called \u201cQFS region\u201d (where reactants accumulation is low and all the heat released is readily removed by the cooling equipment) and, then, iteratively searching for the constrained system optimum. To manage the software, only a few experimental parameters are needed; essentially: heat(s) of reaction, apparent system kinetics (Arrhenius law), threshold temperature(s) above which unwanted side reactions, decompositions or boiling phenomena are triggered, heat transfer coefficients and reactants heat capacities. Such parameters can be obtained using simple calorimetric techniques (DSC, ARC, RC1, etc..). Over the optimization section, the software posses a simulation section where both normal and upset operating conditions (such as pumps failure and external fire) can be tested

    Comparison between two cases study on water kiosks

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    Bottled water consumption in Europe began in the 70s. Environmental impact derived from water production chain is very significant: for example plastic bottles use, oil consumption for bottle production, air emission from vehicles transporting bottles, not recycled plastic packages, etc. In this research an environmental and economic impact evaluation was presented for two case studies, regarding water kiosk design with the aim of supplying controlled natural and sparkling water with better organoleptic quality compared to water directly supplied from aqueduct

    Aeraulic behaviour of a biotrickling filter pilot plant: experiments and simulations

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    Trickling bed biofilters (or biotrickling filters, BTFs) are biological systems for polluted air treatment. Hydrodynamics of BTFs, and reactors in general, is of paramount importance for obtaining good performances. In fact, a non-uniform distribution of the pollutant into the bed brings to dead zones or bypass which reduce the bed working volume and, therefore, cause low removal efficiencies. The paper presents the preliminary results obtained regarding the aeraulic behavior of a BTF pilot plant with seashells as packing material. Experimental results of bed void fraction and pressure drop at several flow rates were used to obtain Ergun equation coefficients for dry bed. A numerical simulation of the reactor flow field carried out with a commercial CFD (Computational Fluid Dynamics) code, validated by the means of velocity measurements made with a Hot Wire Anemometer (HWA) completed the analysis of the reactor hydrodynamics

    Modeling and simulation of an emulsion copolymerization process

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    Radical emulsion copolymerization is one of the most widely diffused processes aimed to produce paints easy to use because of their low viscosity. At industrial scale, such processes require a high control level of all the operating variables. Particularly, the repeatability of an emulsion polymerization process within narrow limits is one of the most desirable features because it allows for controlling also other important product qualities as final solids content, average particle size, latex viscosity and polymer average molecular weight. Other important full plant requirements are the minimization of reactants dosing times and the preparation of a latex at the highest possible concentration. In this work, the first step of a complex industrial copolymerization process has been considered. Since different monomer types (butyl acrylate, styrene, acrylic acid and acrylamide) are involved, it has been necessary to propose a complete set of rate constants for all the traditional steps of the radical emulsion reactions chain (i.e. initiation, propagation, radicals termination, backbiting and long-chain branching, micelles seeding, etc..). These parameters have then been inserted into a system of ordinary differential equations expressing all balances and control actions aimed to simulate the full plant synthesis. Finally, the proposed model has been experimentally validated through the comparison with a reaction calorimetry test carried out in an indirectly cooled semibatch reactor (RC1, 1L, Mettler Toledo). Obtained results have confirmed the reliability of the theoretical model

    IEC 61508: Effect of test policy on the probability of failure on demand of safety instrumented systems

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    Standard IEC 61508 provides probabilistic equations for determining the Average Probability of Failure on Demand (PFDavg) and the Average Probability of Failure per Hour (PFHavg) for some architectures of Safety Instrumented Systems (SIS) under the hypothesis of equal redundant components, taking into account Common Cause Failures (CCF), Detection Coverage (DC) and Proof Test Coverage (PTC) parameters. Surprisingly, IEC standard does not mention the testing policy aspects of SIS redundant components. However, from a close examination of the probabilistic equations, it is possible to recognize that the simultaneous/sequential testing policy has been implicitly assumed. This paper describes the conditions under which the staggered testing policy - which is better than all the others in case of independent tested components - can be advantageously applied to reduce PFDavg when CCF, DC and PTC parameters are taken into account

    Safe optimization of 2-octanol oxidation and vinyl acetate emulsion polymerization

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    In this work the possibility to develop reliable optimization procedures, particularly suitable for full plant exothermic semibatch processes operated in the isoperibolic temperature control mode, has been investigated. It has been found that a general optimization procedure could be developed by using a particular curve, called topological curve, resulting from the numerical solution of the ordinary differential equation system describing the process dynamics. Such a curve exhibits a series of inversion points that represent, physically, transitions between different system thermal behaviour regions. The optimization procedure based on the analysis of the topological curve uses the QFS inversion as a boundary beyond which the optimum operating conditions can be searched accounting for reacting mixture thermal stability and desired productivity constraints. Experimental temperature vs. time data spring from laboratory studies of two different potentially runaway systems (the nitric acid oxidation of 2-octanol to 2-octanone and the free radical emulsion homopolymerization of vinyl acetate) have been modelled to demonstrate that the topological criterion for the QFS detection is independent of all the thermodynamic and process variables control equations used to describe the system. Such a result suggests that this approach could be safely used to optimize even processes operated at the full plant scale

    Bacterial contamination of saline nasal irrigations in children: An original research

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    Microbiologic analysis of nasal saline irrigations (NSIs) used in hospitalized children was performed. Of 253 collected samples, 24.9% were positive, and the number of positive samples significantly increased over time (P < .001). Staphylococcus aureus was the most frequently detected bacterium (28.6%). None of the 118 patients who received NSIs developed a nasosinusal infection. Colonization by cutaneous and environmental germs is frequent and develops early. Hygienic measures should be advocated to reduce contamination
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