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Utilization of fluidized bed combustion solid residues in the production of refractories
Tvrdý, Michal ; Novotný, Radoslav (referee) ; Opravil, Tomáš (advisor)
The thesis deals with the preparation, study and analysis of refractory ceramics, namely fireclay mortars for stove purposes with the addition of fluid ash. The mixtures for preparation of refractory ceramics were doped with different content of fly and bed fluid ash in order to reduce the consumption of the original raw materials for the preparation of these materials. Fired slate clay, refractory clay, fly and bed fluid ash were used for preparation the samples. Input raw materials and fired fireclay mixtures were characterized by XRD, TG-DTA-EGA, TDA, SEM-EDS, heat microscopy, isothermal calorimetry, ICP-OES. The mechanical properties, i.e. compressive strength and tensile bending, were also determined on fired fireclay mortars. The results showed that the properties of the fireclay mortar containing fly ash are comparable to the starting mortar to a specific ash dosage. It has also been found that bed fluid ash is not suitable for the production of refractory materials.
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Application of fly ashes from fluid bed coal combustion within refractory materials
Kotrla, Jan ; Bartoníčková, Eva (referee) ; Šoukal, František (advisor)
The thesis deals with the possibility of utilization of fluid ash in refractory materials and its influence on resulting properties. This work studies the effect of bed and filter ash addition on properties of the droplet and resulting mechanical properties, bulk density, shrinkage and firing temperature of stove fireclay. The subject of this thesis is also reduction of SO2 emissions evolved burning of fireclay containing fluid ash rich of anhydrite. Emissions of SO2 were observed by TG-TDA-EGA method. Characterization of prepared samples and study of heat treatment processes was based on XRD, TG-DTA-EGA, TDA, SEM–EDS, heating microscope and isothermal calorimetry.
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Vanadium corrosion of refractory materials
Florian, Ondřej ; Opravil, Tomáš (referee) ; Ptáček, Petr (advisor)
The bachelor thesis is focused on the influence of vanadium corrosion process on the corrosion and properties of high-alumina refractory products used in gasified on production of synthesis gas from a carbon feedstock, water on oxygen. The composition, properties of refractory product and mutual interaction of corrosion processes was investigated by method of thermal analysis, X-ray diffraction analysis and scanning electron microscopy.
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Inhibition of hydrogen evolution in aluminum-phosphate refractory binders
Bednárek, Jan ; Kalina, Lukáš (referee) ; Šoukal, František (advisor)
The thesis deals with the possibilities of inhibition of the reaction of aluminium-phosphate binders with wear iron, which is contained in bauxite. This material is mixed with phosphate binders to form refractories. The hydrogen is produced by this reaction causing the mixture foaming. The amount of evaluated hydrogen was observed by the measuring by the Jank’s calcimeter. Also the shape of oxidation-reduction potential of the binders was measured before and after mixing with aggregate, using potentiometer. The influence of the addition of various cations on the hydrogen evolution and on the oxidation-reduction potential was observed. The effectiveness of the inhibitors was studied also visually by forming test elements.
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The optimization of phosphate binders compozition used for refractories
Kalousová, Hana ; Ptáček, Petr (referee) ; Opravil, Tomáš (advisor)
This thesis deals with optimization of the composition phosphate binders. These binders are used in production of refractories. In this branch, the bauxite is very often used as an aggregate, but it contains tiny particles of iron which arise in milling process. These particles of iron react with the phosphate binder to form hydrogen – it is consequence of the reaction between phosphoric acid and iron. The formed gas causes the formation of bubbles and the deformation of refractories. The goal of this thesis is to find suitable additives which can be used to stop or to limit the production of hydrogen. Usually used binders were replaced by a model binder to simplify the system and for better understanding. The model binder was prepared in laboratory by dissolving aluminium hydroxide in phosphoric acid. They used pure powdered pentacarbonyl iron instead of tiny iron particles from the milling process. The model binder was modified with using a few inhibitors. The calcimetr was used to measure their influence on the production of hydrogen, as well as measuring concentrated rows of selected inhibitors. These rows are necessary to optimize the inhibitors quantity added in the binder.
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Vliv podávání prášku na mechanické vlastnosti plazmových nástřiků mědi a wolframu
Mušálek, Radek ; Matějíček, Jiří
Nuclear fusion is considered to be a promising energy source for the future. One of the biggest problems which has to be solved is the development of inner wall material of the fusion reactor. For the inner parts which will be exposed to high levels of heat and particle flux, a combination of tungsten layer on copper parts was proposed. Tungsten is refractory material resistant to high heat and particle flux, while copper can efficiently remove heat due to its high thermal conductivity. But high stress concentration on the materials interface can occur due to the thermal expansion coefficient (CTE) mismatch of both materials when exposed to high temperatures. Therefore plasma spraying is promising technology for this application. One of the critical plasma spraying parameters is the carrier gas flow which has to be optimized to ensure proper particle trajectory along the centerline of the plasma flame. Obtained results are currently being used for the development of FGM coatings.
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