Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / A necessidade de redução da emissão de poluentes, visando diminuir os sérios problemas de poluição atmosférica enfrentados atualmente, é hoje uma das principais preocupações mundiais, provocando o surgimento de leis mais rígidas, que restringem o teor de enxofre na gasolina e no diesel. Assim, o desenvolvimento de tecnologias mais eficazes na remoção de enxofre nestes combustíveis tem recebido atenção crescente. Estas tecnologias incluem a extração física com solvente, a adsorção seletiva, processos de redução/oxidação microbiológicos e a dessulfurização oxidativa (ODS). A dessulfurização oxidativa converte os compostos de enxofre em sulfonas que podem ser facilmente separadas por processos físicos. Portanto, a ODS apresenta grande potencial para tornar-se um processo complementar a processo de hidrodessulfurização tradicional na produção de combustíveis altamente dessulfurizados. Neste contexto, este trabalho visou o estudo do desempenho de catalisadores de V2O5 suportados em alumina, sílica e sílica-alumina frente à reação de ODS do dibenzotiofeno em presença do peróxido de hidrogênio, como oxidante, e da acetonitrila, como solvente polar aprótico. Os catalisadores foram preparados por impregnação ao ponto úmido e caracterizados por difração de raios-X (DRX), análise textural, redução à temperatura programada (TPR-H2), dessorção de amônia à temperatura programa (TPD-NH3) e espectroscopia Raman. O efeito de parâmetros reacionais como quantidade de solvente, relação O/S e concentração de catalisador foram investigados, utilizando a alumina como suporte, visando estabelecer as condições reacionais que levassem a maiores valores de conversão do dibenzotiofeno (DBT). Uma vez estabelecidas estas condições, foi analisado o efeito do teor de V2O5 presente no catalisador e, posteriormente, o efeito do suporte catalítico. Os resultados obtidos mostraram a 70 C razão molar H2O2/Sde 16,6, razão carga/solvente igual a 1:1 e 100 mg do catalisador 15 % V2O5/SiO2, a conversão obtida foi de 95% / The need to reduce the gaseous emissions which causes serious environmental problems is a worldwide concern nowadays. Therefore, stricter laws aiming at to reduce the sulfur content in gasoline and diesel are being adopted in different countries, among them Brazil. Thus, the development of more efficient technologies to remove sulfur in these fuels has received increasing attention. These technologies include the physical extraction with a solvent, selective adsorption, microbiological reduction/oxidation processes and oxidative desulphurization (ODS). The oxidative desulfurization (ODS) converts sulfur compounds into sulfones that can be easily separated by physical processes. Therefore, the ODS has a great potential to become a process complementary to traditional hydrodesulfurization in the production of highly desulfurized fuels. In this context, this work studied the performance of V2O5 catalysts supported on alumina, silica and silica-alumina toward ODS reaction of dibenzothiophene in the presence of hydrogen peroxide as the oxidant, and acetonitrile as polar aprotic solvent. The catalysts were prepared by incipient wetness impregnation and characterized by X-ray diffraction (XRD), textural analysis, temperature programmed reduction (TPR-H2), temperature programmed desorption (TPD-NH3) and Raman spectroscopy. The effect of experimental parameters such as amount of solvent, O/S ratio and catalyst concentration were investigated, using alumina as a support, aiming at establishing the conditions that could lead to the higher conversion of dibenzothiophene (DBT). Once established these conditions, the effect of V2O5 content was investigated and then the effect of catalytic support. The results showed that at 70 C, H2O2/S molar ratio of 16.6, solvent/diesel ratio equal to 1: 1 and 100 mg of 15% V2O5/SiO2 catalyst, the conversion obtained was 95%

The main goal of my diploma work was global analysis of the logistic system in the mining industry especially processing limestone. The mining and processing limestone in Vapenka Certovy schody a.s. are devided to the several technological operations with logical sequences. Strict directions are provided for any technological operations. Final products are delivered in high quality to the customers thanks to these strict directions. The next part of my diploma work was to find optimal solution delivery quotas ground limestone kind D5 for ECK Generation s.r.o. I found the best possibility of delivery from between truck and railway. I recommended the group of 7 lowry kind RAJ drawn by 1 gas-power locomotive. It is the cheapest solution and very ecological too.

The topic of this dissertation was the preparation of a high-quality sulphate binder based on secondary raw materials. For this purpose, the work was primarily focused on the laboratory preparation of beta gypsum from the selected industrial gypsum, the design of the technological process of production and its verification by pilot tests. In the next step, the thesis dealt with the modification of beta gypsum by a selected set of liquefiers. In addition to commercial dehumidifiers, the possible beta casting of beta gypsum was tested by increasing the zeta potential of the gypsum suspension. At the end, a complete complex of construction products was developed based on laboratory and semi-prepared beta plasters, consisting of gypsum plasters, mastics, gypsum premix and small plaster casts.

>Magister Scientiae - MSc / Over the past 5 years, South Africa has been experiencing a severe drought. This has caused industrial and agricultural processes, to compete for a limited supply of water. Since the economy relies mostly on agricultural activities, water consumption by industrial processes is taking its toll. One of these processes is the introduction of wet flue gas desulphurization (FGD) treatment at Eskom coal fired power stations. This dissertation explores the possibility of using membrane technology as a means of water recovery after the coal combustion flue gas has been treated with wet FGD. A lab-scale permeance testing system was specially built and modified to have complete thermal control of the environment inside the system. The permeance testing system produced a gas, similar to that of a wet FGD treated flue gas, which was then tested. A tubular lab-scale membrane module was designed and produced for the permeance testing system. The permeance figures of both Nitrogen gas and water vapour were determined for the membrane used in module production. These figures coincided with figures provided by the supplier, which warranted successful permeance testing. After success of the lab-scale testing, the data was used to design and develop a pilot-scale membrane module. This module was designed to meet pre-determined requirements as set forth by the project team. Producing lab-scale membrane modules helped identify and address possible problems in pilot-scale module design. This lead to the successful design and construction of a pilot-scale membrane module that could be used to recover the water that is needed to run the wet FGD process.

In this thesis work, some basic concepts about desulphurizationof hot metal have been done based on a literature study. Two experimentaltrials have also been carried out to study the slags: one consider as areference and in the other trial, the amount of calcium carbide was reduced by150 kg. The average carbide efficiency has been improved from 21.3% in trial 1 to 26.0% in trail 2. Metaldroplets containing iron oxides are found in three of eight heats and most ofmetal droplets are surrounded by Ti-compounds. The slags mainly consisted of (Ca,O, Si) and (Ca, S), with some low content of other elements.

Seawater flue gas desulphurization (SWFGD) is a reliable and efficient process to re-move sulfur dioxide in flue gases in power plants and industries. The characteristics and applications of seawater treatment plant of three SWFGD process are described firstly. A literatual survey looking at different air injection techniques in shallow water basin applications are investigated, also including best practice from similar applications in other types of industries. A number of promising alternatives is then selected and compared with today’s system. The relevant experimental data of these systems are collected. A rate-based model is developed to simulate and optimize the aeration process in seawater treatment plant after its reliability is verified by the experimental data.

Seawater flue gas desulphurization (SWFGD) is a reliable and efficient process to re-move sulfur dioxide in flue gases in power plants and industries. The characteristics and applications of seawater treatment plant of three SWFGD process are described firstly. A literatual survey looking at different air injection techniques in shallow water basin applications are investigated, also including best practice from similar applica-tions in other types of industries. A number of promising alternatives is then selected and compared with today’s system. The relevant experimental data of these systems are collected. A rate-based model is developed to simulate and optimize the aeration process in seawater treatment plant after its reliability is verified by the experimental data.

Steel cleanliness as a function of stirring practice during vacuum degassing treatment have been investigated in industrial studies at the steel plants of SSAB Special Steels in Oxelösund and Uddeholm AB in Hagfors. The cleanliness was examined with regards to the contents of sulphur, nitrogen and large inclusions (&gt;10µm). The stirring practice during the vacuum degassing treatment has been studied with respect to time, namely by shortening the vacuum degassing treatment time from 24 to 15 minutes. Furthermore, the effect of the stirring intensity was studied by measuring the open eye zone using camera recordings. The focus has been to study the effect of a shortened vacuum degassing time as well as a controlled stirring intensity on the steel cleanliness. Moreover, study the effect of subsequent induction stirring, after vacuum degassing, on the amount of inclusions. By taking steel and slag samples taken before and after the vacuum degassing treatment, the different stirring practices could be investigated. It should be noted that all heats reached the desired composition regardless of the treatment time and stirring practice. The results from the trials at SSAB Special Steels showed that the stirring practice during vacuum degassing have an effect on the total number of inclusions. The strong argon stirring during vacuum degassing with visible open eyes resulted in an average increase of 400% of the total amount of inclusions &gt;10µm. However, no difference between a vacuum degassing time of 24 or 15 minutes was seen with respect to the increased amount of inclusions, denitrogenization or desulphurization. During the subsequent induction stirring, which was softer with no open eyes, the effect of the stirring practice was unclear due to overlapping confidence intervals. An average decrease of 65% of the total amount of inclusions &gt;10 µm was seen for the heats  with non-overlapping confidence intervals. Based on these results it can be suggested that the use of a soft induction stirring after the vacuum degassing treatment as a possible process change to reach lower amounts of large inclusions. The stirring intensity during the vacuum degassing treatment was measured as the average ladle eye size during the trials at Uddeholm AB. This, due to that stronger stirring results in larger ladle eye zone. The results show that the amount of smaller inclusions (&lt;11.2 μm) decrease by up to 90% compared to the original amount, regardless of the stirring intensity. A stronger stirring showed tendency to increase the amount of large inclusion (&gt;22.4 μm). Moreover, the denitrogenization and desulphurization was not affected by the changed stirring intensity during vacuum degassing. It was also found that the average ladle eye size did not correlate to the logged average argon flow. / <p>QC 20150522</p>

This bachelor degree project is about determining the impact that additional bottom stirring may have on the desulphurization process at SSAB Luleå. During one week of field work steel samples were collected from 39 different heats. 31 of the heats were samples with the bottom stirring function enabled and the remaining 8 heats without the bottom blowing function, which is the standard method today at SSAB Luleå and they can be referred as references. Data from 15 old reference heats were also used for analysis.Two different behaviors of bottom stirring appeared and they were therefore separated to type 1 and type 2 bottom stirring. Type 1 bottom stirring turned out to have highest possibility of all methods to reach dissolved sulfur content of maximum 0.001%. If the ingoing dissolved sulfur content is around 0.03% has type 1 bottom stirring 33% chance to reach 0.001% dissolved sulfur content already after 13.3 minutes of injection and that can save sulfur reagents. The method with highest reagent efficiency showed type 1 bottom stirring to have, on second place came type 2 bottom stirring and the references showed to have lowest reagent efficiency.

Heightened concerns for cleaner air and increasingly more stringent regulations on sulphur content in transportation fuels will make desulphurization more and more important. The sulphur problem is becoming more serious in general, particularly for diesel fuels as the regulated sulphur content is getting an order of magnitude lower, while the sulphur contents of crude oils are becoming higher. This thesis aimed to develop a desulphurisation process (based on oxidation followed by extraction) with high efficiency, selectivity and minimum energy consumption leading to minimum environmental impact via laboratory batch experiments, mathematical modelling and optimisation. Deep desulphurization of model sulphur compounds (di-n-butyl sulphide, dimethyl sulfoxide and dibenzothiophene) and heavy gas oils (HGO) derived from Libyan crude oil were conducted. A series of batch experiments were carried out using a small reactor operating at various temperatures (40-100 °C) with hydrogen peroxide (H2O2) as oxidant and formic acid (HCOOH) as catalyst. Kinetic models for the oxidation process are then developed based on 'total sulphur approach'. Extraction of unoxidised and oxidised gas oils was also investigated using methanol, dimethylformamide (DMF) and N-methyl pyrolidone (NMP) as solvents. For each solvent, the 'measures' such as: the partition coefficient (KP), effectiveness factor (Kf) and extractor factor (Ef) are used to select the best/effective solvent and to find the effective heavy gas oil/solvent ratios. A CSTR model is then developed for the process for evaluating viability of the large scale operation. It is noted that while the energy consumption and recovery issues could be ignored for batch experiments these could not be ignored for large scale operation. Large amount of heating is necessary even to carry out the reaction at 30-40 °C, the recovery of which is very important for maximising the profitability of operation and also to minimise environmental impact by reducing net CO2 release. Here the heat integration of the oxidation process is considered to recover most of the external energy input. However, this leads to putting a number of heat exchangers in the oxidation process requiring capital investment. Optimisation problem is formulated using gPROMS modelling tool to optimise some of the design and operating parameters (such as reaction temperature, residence time and splitter ratio) of integrated process while minimising an objective function which is a coupled function of capital and operating costs involving design and operating parameters. Two cases are studied: where (i) HGO and catalyst are fed as one feed stream and (ii) HGO and catalyst are treated as two feed streams. A liquid-liquid extraction model is then developed for the extraction of sulphur compounds from the oxidised heavy gas oil. With the experimentally determined KP multi stage liquid-liquid extraction process is modelled using gPROMS software and the process is simulated for three different solvents at different oil/solvent ratios to select the best solvent, and to obtain the best heavy gas oil to solvent ratio and number of extraction stages to reduce the sulphur content to less than 10 ppm. Finally, an integrated oxidation and extraction steps of ODS process is developed based on the batch experiments and modelling. The recovery of oxidant, catalyst and solvent are considered and preliminary economic analysis for the integrated ODS process is presented.