Magnetic separation of ilmenite used as an oxygen carrier in fluidized bed combustion

This bachelor thesis studies how oxidation and reduction cycles during oxygen carrier aided combustion (OCAC) operation, as well as ash interaction, affect the magnetic susceptibility of ilmenite particles used as oxygen carriers. Magnetically separated samples of bottom ash collected from Kraftringen’s circulating fluidized boiler located in Örtofta (Sweden) were analysed. The samples were part of an OCAC campaign from April 2018, in which waste wood and wood chips were used as fuel. Particles from the fresh material, the bottom ash, as well as the fractions separated by a magnet - the magnetic fraction (magnetic accept) and the non-magnetic fraction (magnetic reject) collected from different days were morphologically and chemically characterized using SEM-EDS. XRD was used for crystalline compounds identification and XRF was used for the analysis of the bulk composition of the samples. The aforementioned analysis were complemented with magnetic susceptibility measurements of the samples. The separation of the magnet was found not to be totally effective as artifacts (namely feldspar in the magnetic fraction and inactivated ilmenite in the magnetic reject) were detected in the samples. The results indicate that prolonged residence time of the bed material in the boiler increased the presence of CaTi0.8Fe0.2O2.9 enrichments in the ash layer of the particles from the magnetic accept fraction. It was observed that ash compounds do not interfere significantly in the bulk magnetic susceptibility. Magnetic susceptibility increased with longer residence time, where the suggested cause behind it was the possible Fe2+ migration towards the surface of ilmenite particles, and its oxidation to magnetic Fe oxides – titanomagnetite and hematite. The results from the work suggest that the magnetic susceptibility of bed material increases with residence time in the boiler, and so does the ash uptake. Early separation can result in fresh material ending in the magnetic reject fraction. Based on these results, an optimal time window for the extraction, separation, recirculation and/or renewal of the bed material can be defined that will likely result in an increase in separation efficiency of the bed material. Therewith, magnetic susceptibility measurements could be a useful tool in the optimization and decision making regarding this time window.Outgoin

The literal sense and the spiritual understanding of Scripture according to St. Thomas Aquinas

In contemporary Biblical hermeneutics, there is a confusion about what the literal and spiritual senses are. From this confusión, it follows that the interpreter does not know the sense to be reached and that there is a considerable distance between what the Bible meant when it was written and what it now means in the Church. St. Thomas has a clear doctrine about what is the literal sense and what the spiritual sense, which can clarify this confusion and avoid the negative consequences it has for exegesis. From this doctrine, there are two essential contributions that can serve this purpose: the literal sense is mainly the sense intended by the divine author, and the spiritual understanding is what allows the interpreter to reach the literal sense of the New Testament, the key that opens up the meaning of revelation and of Scripture.Sens dosłowny i sens duchowy rozumienia Pisma Świętego według św. Tomasza z AkwinuWe współczesnej hermeneutyce biblijnej istnieje zamieszanie dotyczące tego, czym jest dosłowny i duchowy sens. Z tego zamieszania wynika to, że interpretatorzy nie wiedzą, jaki jest sens, który mają osiągnąć i jaki jest dystans między tym, co Biblia znaczyła, kiedy była napisana i co teraz znaczy w Kościele. Św. Tomasz podaje jasną doktrynę o tym, czym jest sens dosłowny i duchowy, która może wyjaśnić to zamieszanie i uniknąć jego negatywnych skutków dla egzegezy. Z tej doktryny wynika, że sens dosłowny jest tym, który zamierzał sam autor, duchowy zaś jest tym, co uznaje interpretator, aby ubogacić dosłowny sens Nowego Testamentu. Jest to klucz, który poszerza znaczenie objawienia i Pisma Świętego

Saint Paul's Thorn in the Flesh: a Dermatological Weakness?

Saint Paul's thorn in the flesh has been the subject of much controversy in medical, historical and religious literature. It was crucial for the development of Paul's theology and, therefore, its study is important for a better understanding of early Christianity. The purpose of this article is to review the available evidence on this issue, perform a historical and medical critical analysis and suggest plausible diagnosis that have not been previously published in scientific literature. Our research on primary sources seem to indicate that in 41-42 AD Paul of Tarsus developed a clinical picture with a pain similar to that of a thorn injury and bad physical appearance. It could also have a chronic course with a limited number of relapses and few global. It could remind Job's illness and provoke humiliation in Paul and repulse in his audience. Multiple diseases could explain some of these data, but fewer explain all of them. Though a definitive diagnosis cannot be achieved, we think that cutaneous disorders are the most obvious candidates for a humiliating and painful disease which, however, would permit long journeys during more than a decade. Disorders with cutaneous involvement like lupus erythematosus, dermatomyositis, urticaria/angioedema, herpes simplex leukocytoclastic vasculitis or nodular vasculitis should be added to other possibilities previously reported

Magnetic properties of ilmenite used for oxygen carrier aided combustion

Oxygen carrier aided combustion is a combustion process that utilizes oxygen carrying particles in a fluidized bed to transport oxygen from oxygen-rich to oxygen-poor regions in the reactor. A commonly used oxygen-carrying material is ilmenite (FeTiO3) which is a naturally occurring mineral. At higher oxygen partial pressures ilmenite can react to pseudobrookite (Fe2TiO5) and thereby take up oxygen. Upon reduction of pseudobrookite in oxygen-lean locations the oxygen is released, which enhances the distribution of oxygen through the reactor. Ilmenite was used as bed material in an industrial 115 MWth circulating fluidized bed (CFB) boiler where recycled waste wood and wood chips were utilized as fuel. Bottom ash samples were extracted after one and two weeks and the samples were separated into two fractions by a magnetic separator. The magnetic fraction was expected to be enriched in iron-containing oxides and was therefore aimed to be recirculated into the boiler. The SEM-EDS analysis revealed that the non-magnetic fraction consists to the largest extent of feldspar (KAlSi3O8) particles. A significant amount of freshly introduced ilmenite particles was also classified as non-magnetic by the magnetic separator. Characteristic for these particles was a lack of ash layer, suggesting they had only recently been added to the system. In the magnetic fraction, several feldspar particles were found which were covered by a layer rich in Ca, Fe, Ti, and Si. Comparing the XRD analysis of the ash prior to magnetic separation with its magnetic fraction revealed a decrease of the peaks corresponding to feldspar. The removal of feldspar particles by magnetic separation was further corroborated by XRF analysis, where the concentration of K, Al and Si was significantly higher in the non-magnetic fraction, however, no changes were observed in the concentration of Fe. The present analyses shows that prolonged exposure time of ilmenite increases its magnetic susceptibility. Non-magnetic feldspar was shown to acquire significant magnetic susceptibility by formation of a surface layer containing Fe-rich attrition products from ilmenite

Direcció estratègica de sistemes i tecnologies de la informació, setembre 2012

Material docent de la Universitat Oberta de Catalunya.Material docente de la "Universitat Oberta de Catalunya".Learning material of the "Universitat Oberta de Catalunya"

Dirección estratégica de sistemas y tecnologías de la información, septiembre 2012

Material docent de la Universitat Oberta de Catalunya.Material docente de la "Universitat Oberta de Catalunya".Learning material of the "Universitat Oberta de Catalunya"

Ley Evangélica y Caridad según santo Tomás de Aquino

S. Pinckaers asked rhetorically: is St. Thomas’ moral doctrine Christian? The question was justified by the common accusation that Aquinas’ moral theology was more Aristotelian than evangelical. Such an accusation responds to a superficial reading of the doctrine of St. Thomas. The present article tries to show the supernaturality of one of the structuring elements of St. Thomas’ moral theology, the Evangelical Law or New Law. We can see its supernaturality in its interior nature due to the grace of the Holy Spirit, as well as in its content and motive of charity. On the other hand, this supernaturality is also evident when we see how Saint Thomas grasped it from the Holy Scripture, especially in one of its most decisive points: the interior character of the knowledge proper to the New Law.S. Pinckaers se preguntaba retóricamente: ¿la moral de santo Tomás es cristiana? La pregunta tenía su razón de ser ante la común acusación de que la moral del Aquinate es más aristotélica que evangélica. Tal acusación responde a una lectura superficial de la doctrina de santo Tomás. El presente artículo trata de mostrar la sobrenaturalidad de uno de los elementos estructurantes de la moral de santo Tomás, la Ley Evangélica o Ley Nueva. Su sobrenaturalidad se manifiesta principalmente al considerar su naturaleza interior debida a la gracia del Espíritu Santo, así como su contenido y motivo de caridad. Por otra parte, esta sobrenaturalidad queda también patente al ver cómo santo Tomás la ha tomado de la lectura de la Sagrada Escritura, especialmente en uno de sus puntos más decisivos: el carácter interior del conocimiento propio de la Ley Nueva

Direcció estratègica d'organitzacions intensives en SI/TI, setembre 2013

Recurs d'aprenentatge de la Universitat Oberta de Catalunya.Recurso de aprendizaje de la "Universitat Oberta de Catalunya".Learning material of the "Universitat Oberta de Catalunya"

Dirección estratégica de organizaciones intensivas en SI/TI, septiembre 2013

Recurs d'aprenentatge de la Universitat Oberta de Catalunya.Recurso de aprendizaje de la "Universitat Oberta de Catalunya".Learning material of the "Universitat Oberta de Catalunya"

Dirección de sistemas de información (Executive), febrero 2014

Recurs d'aprenentatge de la Universitat Oberta de Catalunya.Recurso de aprendizaje de la "Universitat Oberta de Catalunya".Learning material of the "Universitat Oberta de Catalunya"