1,720,970 research outputs found
Comparative environmental analysis of waste brominated plastic thermal treatments
No full textThe aim of this research activity is to investigate the environmental impact of different thermal treatments of waste electric and electronic equipment (WEEE), applying a life cycle assessment methodology. Two scenarios were assessed, which both allow the recovery of bromine: (A) the co-combustion of WEEE and green waste in a municipal solid waste combustion plant, and (13) the staged-gasification of WEEE and combustion of produced syngas in gas turbines. Mass and energy balances on the two scenarios were set and the analysis of the life cycle inventory and the life cycle impact assessment were conducted. Two impact assessment methods (Ecoindicator 99 and Impact 2002+) were slightly modified and then used with both scenarios. The results showed that scenario B (staged-gasification) had a potentially smaller environmental impact than scenario A (co-combustion). In particular, the thermal treatment of staged-gasification was more energy efficient than co-combustion, and therefore scenario B performed better than scenario A, mainly in the impact categories of "fossil fuels" and "climate change". Moreover, the results showed that scenario B allows a higher recovery of bromine than scenario A: however, Br recovery leads to environmental benefits for both the scenarios. Finally the study demonstrates that WEEE thermal treatment for energy and matter recovery is an eco-efficient way to dispose of this kind of waste. (C) 2008 Elsevier Ltd. All rights reserved
Preparation of thin film Pd membranes for H2 separation from synthesis gas and detailed design of a permeability testing unit
No full textHydrogen is one of the most important chem. products and it is used in a wide variety of industrial fields including chem., petrochem., metallurgic and energy applications. Hydrogen demand in all of these fields is continuously growing. At present, hydrogen is mainly produced from fossil fuels via processes such as steam reforming, partial oxidn. and gasification. All of these processes lead to the prodn. of an H2-contg. gas stream (synthesis gas) from which hydrogen has to be sepd. Thin-film palladium membranes are one of the most promising technologies for the sepn. of hydrogen from synthesis gas. It involves some advantages over traditional sepn. methods like pressure swing adsorption (PSA), and over other membrane materials (polymeric, porous or dense ceramic), among which are 100% sepn. efficiency, high permeability and operating conditions compatible with upstream fuel conversion processes. In this work, palladium films were deposited above stainless steel porous supports using the electroless plating (ELP) technique. Two different geometries (disk sheet and tubes) were chosen for the supports, which both have a 0.1 m filter grade. Surface morphol. and cross-section were obsd. through SEM. For each membrane, film thickness was estd. both by wt. gain and by cross-section observation with SEM. A good agreement was found between the two values. The evolution of film thickness and morphol. for increasing ELP cycle no. was studied, as well as the influence of a previous phase of thermal oxidn. of the metallic substrate. Membranes were tested in an appropriate set up for nitrogen tightness in order to individuate local defects. The results showed that after only 4 cycles of deposition a uniform dense film of palladium with a thickness of about 10 m is obtained, but even after 6 cycles a small no. of defects still subsist, probably due to support of local morphol. discontinuities.
Finally, the detailed design of a permeability testing unit is reported, including the fluid dynamic, thermal and mech. dimensioning, the selection of materials and equipment, and some safety considerations. The sketches of the two permeation cells (for the two different membrane geometries) are also reported
H2 separation from gas mixtures through palladium membranes on metallic porous supports
No full textThin-film palladium membranes are one of the most promising technologies for
hydrogen separation from gas mixtures, involving advantages, such as a separation
efficiency approaching 100%, high permeability, and operating conditions compatible
with upstream fuel conversion processes. In this work, palladium films, with thickness
between 10 ìm and 40 ìm, were deposited above stainless steel porous tubular supports
using a modified electroless plating technique. The application of vacuum during
palladium deposition, together with support abrasion and oxidation above 700°C, were
demonstrated to be effective in limiting the presence of film defects.
The prepared membranes were then tested in an experimental set-up using a wide range
of operating conditions (transmembranal pressure 2-20 bar, temperature 300-550°C) in
order to evaluate their performances. A hydrogen permeation flow rate of 0.25 mol/m2s,
with a selectivity with respect to CO2 as high as 5000, was obtained at 450°C and 10 bar
of partial transmembranal pressure.
A mathematical model was set in order to interpolate the experimental data and simulate
the permeation of hydrogen through palladium. A good agreement between
experimental and simulation results was obtained
Radio Frequency Heating for Oil Recovering and Soil Remediation
Get PDFThe paper presents basic principles of RF heating and describes its possible applications for oil extraction and soil remediation, based on the experience obtained by several years of work at Consorzio Polo Tecnologico Magona (CPTM). Activities include a complete approach, which goes through the steps of problem formulation, modeling, and experimentation. It is shown that RF heating can represent a valid alternative to more consolidated techniques for application to oil extraction from oil sand or heavy oil reservoirs and for organic polluted soil remediation, in terms of performances and operational flexibility. In particular, radiofrequency heating can be used in several scenarios where the use of alternative methods (such as steam injection) is not possible or strongly limited by geological or logistic constraints
Integration of a small biofuel refinery in a rural context
No full textIn this work three scenarios of biomass production, conversion and utilization of different biofuels (sunflower crude oil, sunflower refined oil and sunflower methyl-ester) in a rural context are compared. The analysis is referred to the district of Pisa, in Italy. Technical feasibility was analysed by comparing process schemes and safety issues, while environmental impacts were studied by applying the methodology of life cycle assessment. Scenarios involving upgrading of crude sunflower oil (refined oil and biodiesel) require complex plants and the management of dangerous materials, and they produce considerable amounts of wastewater. These scenarios need larger plant size, more complex organization (farm cooperatives) and higher costs than the simple mechanical operations associated with crude oil production. On the other hand the use of low-quality fuels in internal combustion engines can lead to short engine lifetime and high pollutant emissions. The life cycle analysis shows that the biofuel upgrading processes (refining and transesterification) and oil transport have a low influence on the environmental impact, compared to seed cultivation, which is the most impacting step. However fuel upgrading allows a significant reduction in polluting emission during combustion; as a consequence biodiesel results the most sustainable biofuel. (C) 2009 The Institution of Chemical Engineers. Published by Elsevier B.V All rights reserved
Materiali innovativi a base di fibre di basalto: valutazioni prestazionali ed ambientali.
No full textNel presente studio sono stati caratterizzati e testati materiali compositi innovativi a base di fibre di basalto e materiali commerciali a base di fibre di vetro atti alla realizzazione di pannelli termo e fonoisolanti per usi industriali con caratteristiche ottimali per la protezione passiva al fuoco (PFP). In particolare, sono stati condotti test su scala di laboratorio mediante un getto incendiato di idrogeno per valutarne la resistenza al fuoco. Avendo quindi verificato la possibilità di sostituire le fibre di vetro con le fibre di basalto nei pannelli isolanti, è stato condotto uno studio LCA (Life Cycle Assessment) comparativo per valutare le performance ambientali dei due prodotti
Solubility and diffusivity of carbon dioxide in perfluoropolyethers
No full textThe main objective of this work was to obtain new data for equilibrium and transport properties in the absorption of carbon dioxide into liquid solvents not yet investigated to this purpose. To this end, an experimental setup for measuring gas solubility and diffusivity in non-volatile solvents was designed, realized, and tested by comparison with literature data for the methane/. n-dodecane pair. The solubility of carbon dioxide, nitrogen and oxygen in two different perfluoropolyethers, Fomblin® M03 and Fomblin® Y04, was measured at different temperature ranging from 10°C to 100°C and for pressures up to 7bar. The diffusivity of carbon dioxide in the solvents was measured at 25°C and 50°C, through a pressure decay method. The results obtained in terms of carbon dioxide solubility and selectivity over other gases are encouraging for the possible use of Fomblin® perfluoropolyethers for the absorption of carbon dioxide from flue gases of industrial plants, also due to the complete immiscibility with water of this solvents. New compounds with similar chemical structure are being developed and tested in order to maximize the performances of the absorption process
Development and Validation of an Activated Sludge Model for an MBR Equipped Domestic Wastewater Plant
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