324,328 research outputs found
PROCESSI E TECNOLOGIE IMPIANTISTICHE PER IL CONTROLLO DEGLI ODORI NEGLI IMPIANTI DI TRATTAMENTO DELE ACQUE DI SCARICO
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Processi e tecnologie impiantistiche per il controllo degli odori negli impianti di trattamento delle acque di scarico
No full textSafe optimization of potentially runaway processes using topology based tools and software
No full textIn 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 “thermal runaway” 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 “QFS region” (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
Waste incineration in rotary kilns: a new simulation combustion tool to support design and technical change
No full textThis article presents a tool based on a simplified model developed for the combustion processes in a rotary kiln incinerator (slightly
inclined rotating primary combustion chamber). The model was developed with the aim of supporting the design phase of the
incinerator combustion chamber and, at the same time, of investigating possible technical changes in existing plants in order to
optimise the combustion process and the dimension of the rotary kiln (length, diameter) as a function of the characteristics of the
fed waste. The tool has been applied and the obtained results compared with a real incineration plant operating on healthcare waste
located in Rome (Italy). The mass and thermal balances were taken into account, together with kinetic parameters for the combustion
of the specific waste stream. The mass balance considered only the major mass components (carbon, hydrogen, oxygen, nitrogen and
sulphur). The measured external temperatures appear to be in good agreement with the simulated results. A sensitivity analysis of the
plant under different operating conditions was carried out using different input flow rates and excess air ratios, and an assessment was
made of the refractory and insulator properties of the kiln’s behaviour. Some of the simulated results were used during the periodical
maintenance to improve the refractory characteristics in order to reduce the fret and corrosion process
A goitrous model for Bartolomeo Vivarini (1432–1499)
No full textIntroduction: Bartolomeo Vivarini (Venezia 1432c.–Venezia 1499c.) was an Italian painter during the Renaissance. The artist was widely influenced by Andrea Mantegna, whose opera was characterized by personages with anatomical details meticulously described. Materials and methods: Some of the most valued paintings of Bartolomeo Vivarini were analyzed. Purpose of the present article is to describe these artworks focusing on female personages represented with thyroid swelling. Results: A recurring female model in Vivarini’s artworks is portrayed with a goitrous neck. This might display a real prevalence of thyroid diseases among young women in the Renaissance age (e.g. postpartum thyroiditis). Conclusions: Representation of goiter in the artworks of Vivarini and Mantegna reflects the increased anatomic accuracy and knowledge developed in art since Renaissance and Baroque
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