Riccardo Rossi

Flow Motion and Dust Tracking Software for PIV and Dust PTV

Dust resuspension and mobilization in case of loss of vacuum accidents and loss of coolant accidents is an important safety issue for Tokamaks. The Quantum Electronics and Plasma Physics Research Group of the University of Rome Tor Vergata has produced an experimental facility, STARDUST-Upgrade, able to replicate these accidents and to obtain fluid dynamic characterization and dust mobilization information in order to validate CFD models. The authors decided to implement two non-intrusive optical methods, particle image velocimetry (PIV) and shadowgraph technique. Two software programs have been developed to compute numerical values from PIV and Shadowgraph frames, namely Flow Motion and Dust Tracking Software. Flow Motion Software has the capability to extract flow velocity field analyzing consecutive frames. Dust Tracking Software follows the path of single objects (i.e., dust particles) tracing their velocity, direction, and position over time. Two experiments have been realized for each software program in order to validate them: cigarette smoke and burning paper plume have been used for flow motion software, while tungsten dust and flour mobilization have been used for dust tracking software.

Non-invasive assessment of dust concentration and relative dustiness in a dust cloud mobilized by a controlled air inlet inside STARDUST-U facility

In the framework of the on-going research on dust explosion, both a physical and chemical theory and numerical models extensively validated are yet to be found. In order to develop control tools essential to continuously measure a set of key parameters for dust explosiveness, the authors performed stainless steel dust mobilization experiments inside STARDUST-U facility using a controlled air inlet whose features are comparable to the ones typical of several industrial scenarios. Dust particles velocity and concentration within the cloud were measured with non-invasive diagnostics involving imaging techniques and a custom software. The STARDUST-U facility showed capability to provide useful data for validation of numerical models. Furthermore, a custom software allowed to determine the relative dustiness, defined as a non-dimensional parameter proportional to dust concentration and not dependent on dust mass and vessel volume. This study is a first step towards a complete integration of the air inlet modeling and dust tracking software, in order to determine dustiness inside the cloud. The authors believe that the imaging techniques presented could represent a valuable tool for industry in order to perform continuous monitoring of vessels with the aim of controlling and mitigating dust explosion risks.

First tests of a multi-wavelength mini-DIAL system for the automatic detection of greenhouse gases

Considering the increase of atmospheric pollution levels in our cities, due to emissions from vehicles and domestic heating, and the growing threat of terrorism, it is necessary to develop instrumentation and gather know-how for the automatic detection and measurement of dangerous substances as quickly and far away as possible. The Multi- Wavelength DIAL, an extension of the conventional DIAL technique, is one of the most powerful remote sensing methods for the identification of multiple substances and seems to be a promising solution compared to existing alternatives. In this paper, first in-field tests of a smart and fully automated Multi-Wavelength mini-DIAL will be presented and discussed in details. The recently developed system, based on a long-wavelength infrared (IR-C) CO2 laser source, has the potential of giving an early warning, whenever something strange is found in the atmosphere, followed by identification and simultaneous concentration measurements of many chemical species, ranging from the most important Greenhouse Gases (GHG) to other harmful Volatile Organic Compounds (VOCs). Preliminary studies, regarding the fingerprint of the investigated substances, have been carried out by cross-referencing database of infrared (IR) spectra, obtained using in-cell measurements, and typical Mixing Ratios in the examined region, extrapolated from the literature. First experiments in atmosphere have been performed into a suburban and moderately-busy area of Rome. Moreover, to optimize the automatic identification of the harmful species to be recognized on the basis of in cell measurements of the absorption coefficient spectra, an advanced multivariate statistical method for classification has been developed and tested.

Improvement of the shadow tracking setup as a method to measure the velocities values of dark dust in order to reduce the risks of radioactive releases or explosions

The mobilisation of dust is a key security issue in nuclear and industrial plants because it can provoke both explosions (in particular temperature and pressure conditions) and dangerous radioactive releases. This work is focused on the tungsten dust resuspension inside small tank for aerosol removal and DUST (STARDUST)-Upgrade, an experimental facility used to reproduce different conditions typical of the loss of vacuum accidents. In this paper, the authors present the facility and the materials used to mount the experimental setup together with the methods and algorithms implemented to track the dust velocity vectors. Tungsten dust is also analyzed through scanning electron microscopy and X-ray diffraction to find some correlation between the variation of the dust morphology, due to the different experimental conditions, with the dust mobilisation paths. The materials and methods together with the experimental results are analyzed and discussed to demonstrate the implementation with the shadow tracking setup presented in the previous facility STARDUST.

Explosion Risks Inside Pharmaceutical, Agro-alimentary and Energetic Industries as a Consequence of Critical Dust Conditions: A Numerical Model to Prevent These Accidents

The dust explosion is the rapid combustion of dust clouds that happens only in particular condition, described by the dust explosion pentagon. It is one of the most critical safety issues in industrial plants, where there are a large production, mobilization and storage of dust such as pharmaceutical and food industries. This phenomenon causes every year about 2000 explosions, and many are the accidents that have involved injuries and deaths. Therefore, it is clear the importance of developing new methods and technologies to prevent and mitigate this kind of accidents. This work shows how computational fluid dynamics can help in dust explosion prevention. A multiphase numerical simulation of a wheat silo is taken into account. During the filling of a silo, there is a temporal interval where the dust concentration reaches the explosibility range. Therefore, the authors evaluate where and when the silos may explode.

Game Theory as Decision-Making Tool in Conventional and Nonconventional Events

Nowadays, safety and security are two objectives always harder to achieve and manage. International and national politics and economics are complexes, and any decisions must be taken considering all the possible consequences, penalties and advantages. Furthermore, these consequences are usually functions of how the others behave. Therefore, the development of tools, methods and theories able to help decision-makers is needed. Game theory is a mathematical science used in economic, political, psychological and scientific problematics. It is based on a mathematical model that takes into account all the possible interactions and decisions which each “player” could take in considerations. This work shows how game theory can be applied also in conventional and nonconventional events, considering some example of safety and security problematics and analysing advantages and limits of this tool.

Development of a Device to Measure Mass and Resuspension Rate of Dust inside Confined Environments

Abstract A dust explosion is one of the key security issues for many industrial, pharmaceutical and agro-alimentary plants and for the safety of the workers. We have developed an optoelectronic sensor system to determine the mass of deposited dust and the resuspension rate. The authors also mount antennas on an optoelectronic sensor system to perform measurements remotely. The technique used is based on a non-invasive light absorption method. The paper reports a cost analysis in order to demonstrate the possibility to use, in our optoelectronic sensor system, several sensors to monitor large volume. In this paper the authors present the sensor system, the test and calibration of its components together with the results and the error analysis, demonstrating experimentally what is the maximum and the minimum readable range.

Imaging to study dust re-suspension phenomena in case of loss of vacuum accidents inside the pharmaceutical industries

Dust explosion is one of the most dangerous hazards in process industries. The several accidents happened in the last hundred years led to guidelines to prevent and mitigate industries. Unless these, dust explosion events still happen. Development of advanced tools is necessary to reach a definitive way to face these threats. Dust concentration, particle size, velocity, moisture and turbulence of dust are important parameters in determination of dust explosion severity. Therefore, in industries with high risk of dust explosion, these parameters should be monitored and controlled. In this work, the authors show their experimental facility and software to monitor dust velocity. The experiments are performed inside STARDUST-U, an experimental facility to test dust re-suspension in case of Loss of Vacuum Accidents.

Multidisciplinary DSS as Preventive Tools in Case of CBRNe Dispersion and Diffusion: Part 1: A Brief Overview of the State of the Art and an Example – Review

The paper addresses some important issues related to the need for a timely, reliable and accurate tool for the early warning in case of CBRNe events. The state-of-the-art of the currently available tools is briefly presented in the first part of the two-papers set. While the accurate calculation of the dispersion of both lighter- and heavier-than-air contaminants in complex three-dimensional domains is definitely possible with commercially available CFD packages, the time needed to obtain a reliable numerical solution, under the pertinent atmospheric conditions prevailing at the time of the attack, exceeds the requirements of a first-aid intervention. Therefore, it would be advisable to combine these CFD packages with some sort of “intelligent” Decision Support System that makes use of multidisciplinary knowledge base and of some kind of detection-diagnostic-prognostic Expert System. The DSS could be interfaced with some standard early detection tools and ought to include an enhanced diagnostic/prognostic utility based on a specific series of local CFD simulations of dispersion events. Its use ought to be relatively easy for trained personnel. Since the database for the CFD dispersion calculation is by definition “local”, detailed maps of the presumable target areas must be included in the database. The second part of this paper presents a detailed description and one example of application of such an Expert Assisted CFD dispersion calculation, named FAST-HELPS (Fast Hazard estimate of low-level particles spread).

Optical measures of dust velocities and direction during loss of vacuum accidents in confined environment and correlation between dust positions and properties with the resuspension degrees and the velocity modules

Dust explosions are dangerous events that still today represent a risk to all the industries that produce and/or handle combustible dust like the agro-alimentary, pharmaceutical and energy ones. When a dust cloud is dispersed in an oxidant gas, like air, it may reach the explosive concentration range. A model to predict the dust critical conditions, that can cause explosions, is a key factor for safety of operators and the security of the plants. The key point to predict this dust resuspension is to measure the velocity vectors of dust under the accidental conditions. In order to achieve this goal the authors have developed an experimental facility, STARDUST-U, which allow to obtain different conditions of temperature and pressurization rates characteristic of accidents in confined environment. The authors have developed also optical methods and software to analyse different dust resuspension phenomena under different conditions in confined environment. In this paper, the author will present how they measure the dust velocity vectors in different experimental conditions (and for different type of dusts) and how they have related the dust characteristics and positions inside STARDUST-U with the resuspension degree and the velocity values.