This diploma thesis deals with proposal of the steam boiler on combustion uncontaminated wood. For the specified parameters have been implemented stoichiometric calculations and calculations enthalpy burnt gas. In the next part have been dealt with heat balance of the boiler, the efficiency of the boiler, design of the combustion chamber and calculation of particular rating surfaces. The output parametres are temperature, pressure and the amount of steam.

This thesis deals with the calculation of the boiler on stillage. Nowadays, when there's fossil fuels are just biomass seems adequate compensation. The great advantage of biomass boilers is a small amount of emissions, especially the greenhouse gas CO2. Of a given fuel composition is made thermal calculation and dimensioning of heat transfer surfaces of steam boilers. The resulting calculation must follow the parameters of steam at the outlet from the boiler.

The aim of the work is to design a plain wood combustion boiler of 60 t/h output. Fuelling component analysis has been added to the basic boiler parameters. Stechiometric calculations were performed for given fuel composition. Thermal efficiency was set after making thermal balance. Separate convective areas and boiler proportions were designed together with separate steam output parameters (temperature, pressure, amount). Design documentation was added.

The aim of this thesis is to propose a grate steam boiler for combustion of straw from wheat, rye and barley output of 20 t / h The calculation is performed by stoichiometric calculation of elemental analysis to calculate the dimensions of a boiler heating surfaces. Default superheated steam can be used mainly for electricity generation.

This diploma thesis describes the design of steam boiler for combustion natural gas, which has a steam power 80t/hour. In the first phase is performed calculation of stoichiometric amount of combustion air and flue gas. After that follows constructional proposal of the combustion chamber. Furthermore continue by calculation heating surfaces of the boiler. In conclusion, the thesis is focused on designing the injections. To check the accuracy of the results is recalculated heat balance the whole boiler.

The aim of the thesis is the design of the steam grate boilers of 40 t/h for straw burning. The required parameters are generated steam temperature 420 ° C and a pressure of 5.5 MPa. The specified fuel is cereal straw with a calorific value of 9.5 MJ/kg. The calculation is made from the stoichiometric calculation of elemental analysis, to calculate the individual dimensions and heating surfaces of the boiler.

This master´s thesis is dealing with the thermal calculation and design of boilers for natural gas combustion. The aim is to design the heating surfaces, so as to meet the requirements of the steam temperature of 490 ° C, the pressure of 7 MPa and the steam output of 60 t/h.

Waste-fired boilers suffer severely from corrosion of critical components such as superheater tubes. In this work the high temperature corrosion of candidate superheater alloys have been investigated by detailed laboratory studies and controlled field exposures in full-scale boilers. In a laboratory study the detrimental effect of gaseous hydrochloric acid (HCl) on three  different ground surface and preoxidised austenitic stainless steels was investigated. Exposures were conducted in an environment comprising N2-10O2-5H2O-0.05HCl at both 400 °C and 700 °C. A positive effect of preoxidation is evident when the alloys are exposed at 400 °C. Oxide layers formed during preoxidation effectively suppress chlorine ingress and lower the corrosion rate for all three materials while accelerated corrosion and chlorine accumulation at the metal/oxide interface is detected for ground surface specimens. The positive effect of preoxidation is lost at 700 °C and corrosion resistance is dependent on alloying level. At 700 °C metal chloride evaporation contributes significantly to the material degradation. Based on the results, high temperature corrosion in the presence of gaseous HCl is discussed in general terms.  In two different waste-fired boilers measures for counteracting superheater corrosion were investigated. In a grate-boiler the deposit formation and high temperature corrosion of some candidate superheater materials were studied. Metal loss measurements showed unacceptably high corrosion rates for the lower alloyed ferritic steels 13CrMo44 (Fe-1Cr-0.5Mo) and HCM12A (Fe-11Cr-2W), as well as for the austenitic Super 304 (Fe-18Cr-9Ni-3Cu). The corrosion attack for these alloys was manifested by the formation of mixed metal chloride/metal oxide scales. A different type of behaviour was seen for the higher alloyed austenitic steels and nickel-base alloys, which were able to form a chromium-enriched oxide next to the metal. However, the alloys suffered from localised pitting attack. Since analyses of the deposit revealed appreciable amounts of low melting salt mixtures such as ZnCl2-KCl, PbCl2-KCl, FeCl2-KCl and NaCl-NiCl2, oxide dissolution in these molten salts is the probable reason for pitting attack. In a waste-fired boiler ammonium sulphate solution was added to the flue gas and the effect on flue gas and deposit composition was evaluated. It was evident that the sulphur-rich additive reduced the amount of alkali chlorides in both the flue gas and the deposit. Results also indicated that the initial corrosion rates were lowered with the use of ammonium sulphate. It was concluded that using the additive could be a possible strategy for changing the flue gas chemistry so that superheater corrosion is mitigated. / <p>QC 20110414</p>

To reduce the greenhouse effect, the use of renewable fuel has to be increased. As renewable fuel has different characteristics compared to fossil fuel regarding content of trace metals, alkali, chlorine and sulphur, the corrosion characteristics in high temperature energy processes have to be evaluated. This thesis concerns high temperature corrosion in the superheater region of a boiler and the syngas cooler area of a gasifier. For the superheater region, laboratory exposures were performed. The methods included a salt dip exposure, where samples were dipped in an equimolar solution of ZnCl2 and KCl, and two salt bed exposures with different chlorine concentrations, 10 and 20 wt%. Ranking of the materials showed that a Ni content above 10 wt% and Cr above 20 wt% reduced corrosion rates in the salt dip and in the 10% Cl salt bed exposure. For exposure in the 20% Cl bed, even higher alloying was needed. An alumina forming austenitic steel showed future potential in sulphidising-chlorinating environments. For the gasifier region, the effect of HCl in a simulated gasifier atmosphere was studied and also samples exposed in the syngas section of a biomass gasifier were investigated. Metal loss was low for all exposures and it was observed that chlorine had minor influence. For the plant exposed samples, a difference compared to that reported for coal gasifiers was the absence of FeS for the lowest alloyed steel. Instead, a deposit with pronounced content of Zn, Ca, S and O was present on the surface. Zinc was suggested to mitigate corrosion. Thermodynamic modelling was used to explain phases present and to predict the nitridation behaviour of an alumina forming austenitic steel. Equilibrium and kinetic modelling of the nitridation showed good coherence with the observed microstructures. However, the kinetic modelling resulted in larger nitridation depths than observed experimentally which was attributed to the presence of a thin oxide layer on the surface of the samples. / <p>QC 20160510</p>

Cette thèse a été réalisée en cotutelle entre l'Université Technique Nationale Ivan Pul'uj de Ternopil (TNTU, Ukraine) et l’Université Blaise Pascal (Clermont-Ferrand, France). Les travaux ont été effectués au sein de l'Institut Pascal de l’Université Blaise Pascal - Clermont II, de l’IFMA et du CNRS, dans le thème scientifique Matériaux actifs et intelligents, modélisation multi-échelle de l'axe Mécanique, Matériaux et Structures, et au sein de l'Institut Français de Mécanique Avancée. La thèse présentée appartient au domaine scientifique de la mécanique de la rupture et la science des matériaux. L'objectif de la thèse est de développer la méthodologie analytique et expérimentale pour la durée de vie résiduelle des collecteurs du surchauffeur dans les centrales thermiques, en tenant compte des caractéristiques de fonctionnement de chargement thermomécanique. La prédiction de la durée de vie est une tâche cruciale pour un fonctionnement continu des éléments structuraux très chargés et fait partie d'un problème plus large, couvert dans la recherche de la résistance et la durabilité des éléments structurels à haute température dans les équipements d'énergie générateur. Le mémoire décrit l'influence de la température de fonctionnement sur la vitesse de propagation des fissures de fatigue et micromécanismes de rupture dans le matériau du collecteur de surchauffeur. / This thesis was performed under the cotutelle agreement between Ternopil Ivan Pul’uj National Technical University (TNTU, Ukraine) and Blaise Pascal University (Clermont Ferrand, France). The thesis was carried out within Pascal Institute of the Blaise Pascal University - Clermont II, the IFMA and the CNRS, in the Scientific Theme “Active and Smart Materials and Multiscale Modeling” of the Mechanics, Materials and Structures Department, and within the French Institute for Advanced Mechanics. The presented thesis belongs to the scientific field of fracture mechanics and material science. The aim of the thesis is to develop the analytical and experimental methodology for the residual lifetime estimation of the superheater collectors at thermal power stations (TPS), taking into account the operational features of thermomechanical loading. Prediction of lifetime is crucial task for continuous operation of heavy loaded structural elements and is a part of a broader problem, covered in the research of the strength and durability of high temperature structural elements in power-generating equipment. The thesis describes the influence of operating temperature on the fatigue crack growth rate and fracture micromechanisms in the material of the superheater collector.