969 resultados para Production processes


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The present study approaches the economic and technical evaluation of equivalent carbon dioxide (CO(2) eqv.) capture and storage processes, considered in a proposal case compared to a base case. The base case considers an offshore petroleum production facility, with high CO(2) content (4 vol%) in the composition of the produced gas and both CO(2) and natural gas emissions to the atmosphere, called CO(2) eqv. emissions. The results obtained with this study, by using a Hysys process simulator, showed a CO(2) emission reduction of 65% comparing the proposal case in relation to the base case.

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Magdeburg, Univ., Fak. für Elektrotechnik und Informationstechnik, Diss., 2011

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Conceptualization, speech production, ERPs, fMRI

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Magdeburg, Univ., Fak. für Elektrotechnik und Informationstechnik, Diss., 2013

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After an introductory discussion emphasising the importance of electrochemistry for the so-called Green Chemical Processes, the article presents a short discussion of the classical ozone generation technologies. Next a revision of the electrochemical ozone production technology focusing on such aspects as: fundamentals, latest advances, advantages and limitations of this technology is presented. Recent results about fundamentals of electrochemical ozone production obtained in our laboratory, using different electrode materials (e.g. boron doped diamond electrodes, lead dioxide and DSAÒ-based electrodes) also are presented. Different chemical processes of interest to the solution of environmental problems involving ozone are discussed.

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Four multiparous cows with cannulas in the rumen and proximal duodenum were used in early lactation in a 4 x 4 Latin square experiment to investigate the effect of method of application of a fibrolytic enzyme product on digestive processes and milk production. The cows were given ad libitum a total mixed ration (TMR) composed of 57% (dry matter basis) forage (3:1 corn silage:grass silage) and 43% concentrates. The TMR contained (g/kg dry matter): 274 neutral detergent fiber, 295 starch, 180 crude protein. Treatments were TMR alone or TMR with the enzyme product added (2 kg/1000 kg TMR dry matter) either sprayed on the TMR 1 h before the morning feed (TMR-E), sprayed only on the concentrate the day before feeding (Concs-E), or infused into the rumen for 14 h/d (Rumen-E). There Was no significant effect on either feed intake or milk yield but both were highest on TMR-E. Rumen digestibility of dry matter, organic matter, and starch was unaffected by the enzyme. Digestibility of NDF was lowest on TMR-E in the rumen but highest postruminally. Total Tract digestibility was highest on TMR-E for dry matter, organic matter, and starch but treatment differences were nonsignificant for neutral detergent fiber: Corn silage stover retention time in the rumen was reduced by all enzyme treatments but postruminal transit time vas increased so the decline in total tract retention. time with enzymes was not significant. It is suggested that the tendency for enzymes to reduce particle retention time in the rumen may, by reducing the time available for fibrolysis to occur, at least partly explain the variability in the reported responses to enzyme treatment.

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The objective of this paper is to reconsider the Maximum Entropy Production conjecture (MEP) in the context of a very simple two-dimensional zonal-vertical climate model able to represent the total material entropy production due at the same time to both horizontal and vertical heat fluxes. MEP is applied first to a simple four-box model of climate which accounts for both horizontal and vertical material heat fluxes. It is shown that, under condition of fixed insolation, a MEP solution is found with reasonably realistic temperature and heat fluxes, thus generalising results from independent two-box horizontal or vertical models. It is also shown that the meridional and the vertical entropy production terms are independently involved in the maximisation and thus MEP can be applied to each subsystem with fixed boundary conditions. We then extend the four-box model by increasing its resolution, and compare it with GCM output. A MEP solution is found which is fairly realistic as far as the horizontal large scale organisation of the climate is concerned whereas the vertical structure looks to be unrealistic and presents seriously unstable features. This study suggest that the thermal meridional structure of the atmosphere is predicted fairly well by MEP once the insolation is given but the vertical structure of the atmosphere cannot be predicted satisfactorily by MEP unless constraints are imposed to represent the determination of longwave absorption by water vapour and clouds as a function of the state of the climate. Furthermore an order-of-magnitude estimate of contributions to the material entropy production due to horizontal and vertical processes within the climate system is provided by using two different methods. In both cases we found that approximately 40 mW m−2 K−1 of material entropy production is due to vertical heat transport and 5–7 mW m−2 K−1 to horizontal heat transport

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This PhD thesis describes set up of technological models for obtaining high health value foods and ingredients that preserve the final product characteristics as well as enrich with nutritional components. In particular, the main object of my research has been Virgin Olive Oil (VOO) and its important antioxidant compounds which differentiate it from all other vegetables oils. It is well known how the qualitative and quantitative presence of phenolic molecules extracted from olives during oil production is fundamental for its oxidative and nutritional quality. For this purpose, agronomic and technological conditions of its production have been investigated. It has also been examined how this fraction can be better preserved during storage. Moreover, its relation with VOO sensorial characteristics and its interaction with a protein in emulsion foods have also been studied. Finally, an experimental work was carried out to determine the antioxidative and heat resistance properties of a new antioxidant (EVS-OL) when used for high temperature frying such as is typically employed for the preparation of french fries. Results of the scientific research have been submitted for a publication and some data has already been published in national and international scientific journals.

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The research of new advanced processes for syngas production is a part of a European project for the production of a new Gas to Liquid Process (NextGTL). The crucial points in the production of GTL process are the energy required for the air separation used in autothermal reforming or the heat required for steam reforming and the efficiency in carbon utilization. Therefore a new multistep oxy-reforming process scheme was developed at lower temperature with intermediate H2 membrane separation to improve the crucial parameter. The process is characterized by a S/C of 0.7 and O2/C of 0.21 having a smoothed temperature profile in which kinetic regime is easily obtained. Active catalysts for low temperature oxy-reforming process have been studied working at low pressure to discriminate among the catalyst and at high pressure to prove it on industrial condition. It allows the selection of the Rh as active phase among single and bimetallic VIII group metal. The study of the matrix composition and thermal treatment has been carried out on Rh-Mg/Al hydrotalcite selected as reference catalyst. The research to optimize the catalyst lead to enhanced performances through the identification of a limitation of the Rh reduction from the oxides matrix as key point to increase the Rh performances. The Rh loading have been studied to allow the catalyst scale up for pilot process in Chieti in a shape of Rh-HT on honeycomb ceramic material. The developed catalyst has enhanced methane conversion in a inch diameter monolith reactor if compared with the semi-industrial catalyst chosen in the project as the best reference.

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The present study is focused on the development of new VIII group metal on CeO2 – ZrO2 (CZO) catalyst to be used in reforming reaction for syngas production. The catalyst are tested in the oxyreforming process, extensively studied by Barbera [44] in a new multistep process configuration, with intermediate H2 membrane separation, that can be carried out at lower temperature (750°C) with respect the reforming processes (900 – 1000°C). In spite of the milder temperatures, the oxy-reforming conditions (S/C = 0.7; O2/C = 0.21) remain critical regarding the deactivation problems mainly deriving from thermal sintering and carbon formation phenomena. The combination of the high thermal stability characterizing the ZrO2, with the CeO2 redox properties, allows the formation of stable mixed oxide system with high oxygen mobility. This feature can be exploited in order to contrast the carbon deposition on the active metal surface through the oxidation of the carbon by means of the mobile oxygen atoms available at the surface of the CZO support. Ce0.5Zr0.5O2 is the phase claimed to have the highest oxygen mobility but its formation is difficult through classical synthesis (co-precipitation), hence a water-in-oil microemulsion method is, widely studied and characterized. Two methods (IWI and bulk) for the insertion of the active metal (Rh, Ru, Ni) are followed and their effects, mainly related to the metal stability and dispersion on the support, are discussed, correlating the characterization with the catalytic activity. Different parameters (calcination and reduction temperatures) are tuned to obtain the best catalytic system both in terms of activity and stability. Interesting results are obtained with impregnated and bulk catalysts, the latter representing a new class of catalysts. The best catalysts are also tested in a low temperature (350 – 500°C) steam reforming process and preliminary tests with H2 membrane separation have been also carried out.

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Nowadays microalgae are studied, and a number of species already mass-cultivated, for their application in many fields: food and feed, chemicals, pharmaceutical, phytoremediation and renewable energy. Phytoremediation, in particular, can become a valid integrated process in many algae biomass production systems. This thesis is focused on the physiological and biochemical effects of different environmental factors, mainly macronutrients, lights and temperature on microalgae. Microalgal species have been selected on the basis of their potential in biotechnologies, and nitrogen occurs in all chapters due to its importance in physiological and applicative fields. There are 5 chapters, ready or in preparation to be submitted, with different specific matters: (i) to measure the kinetic parameters and the nutrient removal efficiencies for a selected and local strain of microalgae; (ii) to study the biochemical pathways of the microalga D. communis in presence of nitrate and ammonium; (iii) to improve the growth and the removal efficiency of a specific green microalga in mixotrophic conditions; (iv) to optimize the productivity of some microalgae with low growth-rate conditions through phytohormones and other biostimulants; and (v) to apply the phyto-removal of ammonium in an effluent from anaerobic digestion. From the results it is possible to understand how a physiological point of view is necessary to provide and optimize already existing biotechnologies and applications with microalgae.

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Groundwater represents the most important raw material. Germany struggles to maintain the best water quality possible by providing advanced monitoring systems and legal measures to prevent further pollution. In areas involved in the intensive growing of plantations, one of the major contamination factors derives from nitrate. The aim of this master thesis is the characterisation of the Water Protection Area of Bremen (Germany). Denitrification is a natural process, representing the best means of natural reduction of the hazardous nitrate ion, which is dangerous both for human health and for the development of eutrophication. The study has been possible thanks to the collaboration with the University of Bremen, the Geological Service of Bremen (GDfB) and Peter Spiedt (Water Supply Company of Bremen). It will be defined whether nitrate amounts in the groundwater still overcome the threshold legally imposed, and state if the denitrification process takes place, thanks to new samples collected in 2015 and their integration with historical data. Gas samples have been gathered to test them with the “N2/Ar method”, which is able to estimate the denitrification rate quantitatively. Analyses stated the effective occurrence of the reaction, nevertheless showing that it only affects the chemical of the deep aquifers and not shallow ones. Temporal trends concentrations of nitrate have shown that no real improvement took place in the past years. It will be commented that despite the denitrification being responsible for an efficacious lowering in the nitrate ion, it needs reactive materials to take place. Since the latter are finite elements, it is not an endless process. It is thus believed that is clearly necessary to adopt a better attitude in order to maintain the best chemical qualities possible in such an important area, providing drinking water.