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Modelling of fouling and its influence on technical-economic characteristics of tubular heat transfer equipment in units for thermal processing of wastes
Keliš, Michal ; Kohoutek, Josef (referee) ; Jegla, Zdeněk (advisor)
The main subject of this study is the improvement of predicative ability of previously developed mathematical model for prediction of so-called “fouling critical velocity”. Attention is devoted especially to the flue gas side fouling process on active heat transfer surfaces in tubular heat exchange tube banks installed in waste incineration process plants and also a technical – economic analysis based on obtained results. The model improvement consists among others in taking into account another forces (electrostatic, capillary etc.) haven't yet been considered, which influence the mutual contact between flue gas particles in case of sedimentation fouling or the contact between particles and heat exchanger tube walls respectively. The improved model has therefore more predicative ability to the reality of fouling process. The results are used for technical – economic analysis, which determines an optimal heat exchanger design with respect to fouling. Furthermore, the algorithm of this analysis, essential fouling mechanisms, fouled heat exchanger surface cleaning methods as well as fundamental knowledge of fouling coefficient prediction are presented, whereas the emphasis is placed on industrial tubular heat exchange equipment installed in waste incineration process plants.
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Design of river stabilization structures at the Bečva river in OSek
Lokajová, Hana ; ing. Zedníček (referee) ; Julínek, Tomáš (advisor)
This bachelor thesis is dedicated to the solution of channel recessing in Osek nad Bečvou. One part deals with the evaluation of historical perspective of the area of interest. In the next part of this thesis the transport of sediments is described. The following part contains of an evaluation of current state of the selected part of the river Bečva and deals with a regulation of the river. In the end the theoretical suggestion of protective measure is developed.
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Risk assessment design margin of process and power equipment
Horsák, Jan ; Pačíska, Tomáš (referee) ; Jegla, Zdeněk (advisor)
This work is devoted to description of methodology of determining process and power equipment design margins, which is based on assessment of a relative process importance of the equipment in question. The methodology is theoretically analysed, brought into context of common design practice and demonstrated on actual cases. Substantial part of this work analyses heat transfer in general as a base of heat exchanger design process.
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Optimization of the cleaning of the heating surfaces on the coal boiler K1 in Plzeňská teplárenská
Kostrhounová, Petra ; Tomáš, Zdeněk (referee) ; Baláš, Marek (advisor)
This master’s thesis deals with the assessment of cleaning of heat transfer surfaces of a coal-fired steam boiler. The first part is devoted to the description of the knowledge about the formation of deposits, the deposits influence on the operation of the plant and cleaning mechanisms. Then, basic information on the operation, design and method of removal of deposits of the K1 boiler is summarised. Based on this knowledge, operating data from four summer months of boiler operation are analysed to determine the fouling condition of the boiler surfaces and over fifty graphs are produced showing the evolution of selected operating values between each cleaning cycle of the convective and plate superheater as well as air preheater. Subsequently, a parametric model of the K1 boiler at 60 % output is created in PPSD, which allows a more detailed analysis of the boiler operating characteristics and is used for a more thorough interpretation of the operating data. In addition, two models for higher boiler outputs and three theoretical models of operating conditions with different levels of surface fouling were developed. To verify the accuracy of the developed model, a calculation of heat transfer through the outlet superheater is performed. Finally, the calculation of steam consumption for sootblowing is performed.
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CFD modelling of the initial phase of fouling inside convective section of a combustion facility
Zlámal, Filip ; Juřena, Tomáš (referee) ; Strouhal, Jiří (advisor)
The aim of this thesis was to create, based on the knowledge obtained from research, a CFD simulation of initial phase of fouling of solid particles during the combustion of solid fuels. The introduction of the work summarizes the mechanisms of fouling by solid particles. The introduction of the work summarizes the mechanisms of fouling by solid particles. Approaches to modelling the impact and deposition of particles are also described. A model is built, which is implemented in the ANSYS Fluent software with the addition of user-defined functions. The model is tested on a model of the convective part of an experimental device for burning solid fuels.
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Combustion of Solid Fuels in Rotary Kiln and Influence of their Composition on Emissions
Bojanovský, Jiří ; Jegla, Zdeněk (referee) ; Puchýř, Radim (referee) ; Máša, Vítězslav (advisor)
The work is focused on the study of the influence of solid fuel composition on the formation of pollutants during combustion in a rotary kiln. This is a highly topical issue related to the need to increase the share of alternative fuels as a substitute for fossil ones. The author builds on the research already carried out in this area, defines the basic characteristics of the problem under study and formulates hypotheses based on the summary of the current state of knowledge. The main hypothesis is ("The composition of the solid fuel mixture can be chosen in such a way as to reduce the generation of pollutants.") To verify this hypothesis, the author chooses experimental verification in combustion tests on a semi-operational experimental device. For the combustion tests, it was proposed to extend this equipment with apparatus that allows the evaluation of the fouling rate of heat transfer surfaces and the formation rate of particulate matter pollutants. This equipment was successfully used for combustion tests of 6 selected alternative fuels (refuse-derived fuel RDF, sewage sludge, and forest waste). Based on the combustion tests conducted with these sub-fuels, 6 fuel mixtures with high potential for industrial applications were defined. These mixtures were also burned in a rotary kiln. Based on the results obtained, the main hypothesis of the work was confirmed and the fuel mixture consisting of 70 wt.% forest waste, 20 wt.% RDF and 10 wt.% sewage sludge (MIX 6 in the work) was identified as the most suitable alternative to fossil fuels. This mixture did not show any operational problems and the best results were obtained in the formation of gaseous pollutants and particulate matter. The results of this work are a crucial point in the search for a methodology for the specification of suitable alternative fuel blends for combustion in the energy and manufacturing industries.
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Optimization of the cleaning of the heating surfaces on the coal boiler K1 in Plzeňská teplárenská
Kostrhounová, Petra ; Tomáš, Zdeněk (referee) ; Baláš, Marek (advisor)
This master’s thesis deals with the assessment of cleaning of heat transfer surfaces of a coal-fired steam boiler. The first part is devoted to the description of the knowledge about the formation of deposits, the deposits influence on the operation of the plant and cleaning mechanisms. Then, basic information on the operation, design and method of removal of deposits of the K1 boiler is summarised. Based on this knowledge, operating data from four summer months of boiler operation are analysed to determine the fouling condition of the boiler surfaces and over fifty graphs are produced showing the evolution of selected operating values between each cleaning cycle of the convective and plate superheater as well as air preheater. Subsequently, a parametric model of the K1 boiler at 60 % output is created in PPSD, which allows a more detailed analysis of the boiler operating characteristics and is used for a more thorough interpretation of the operating data. In addition, two models for higher boiler outputs and three theoretical models of operating conditions with different levels of surface fouling were developed. To verify the accuracy of the developed model, a calculation of heat transfer through the outlet superheater is performed. Finally, the calculation of steam consumption for sootblowing is performed.
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Hydrological and suspended load regime of the Odlezelské Lake
Hulec, Filip ; Šobr, Miroslav (advisor) ; Kliment, Zdeněk (referee)
The Odlezelské Lake is a natural, landslide-dammed lake in western Bohemia. Its lake basin is silting intensely and its volume decreases; it will be completely silted in the future. This work aims to evaluate the siltation of the lake primarily by evaluating the suspended load regime of its tributaries and comparison with data from bathymetric measurements. Within this work, data from the station network of the Department of Physical Geography of the Faculty of Science of the Charles University were used, which was statistically processed in order to describe the hydrological and suspended load regime. In addition, flow speeds in the inflow part of the lake were measured during two precipitation-runoff events using ADCP. The results show that most of the suspended load is transported during flood episodes, in contrast to the runoff, there is a significant interannual variability in the suspended load regime. Oppositely, the comparison of the suspended load regime and the bathymetric data proved as impossible due to a high sensitivity of the data.
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Siltation of the Újezd water reservoir
Kebertová, Daniela ; Šobr, Miroslav (advisor) ; Chalupová, Dagmar (referee)
This bachelor thesis focuses on the siltation of water bodies. In April 2020 the first accurate and detailed bathymetric survey of the Újezd water reservoir was conducted using an ADCP RiverSurveyor M9. The aim of the measurement was to determine volume of the reservoir after 39 years since its construction. The obtained data was processed in ArcMap 10.7.1 using the kriging method of interpolation. Based on it a new bathymetric map of current state of the reservoir was created. For the sake of understanding the causes of siltation, a complex physical-geographic characteristics of the upper stream basin of Bílina river, on which the Újezd water reservoir is situated, had been done. The river basin is fundamentally anthropogenically influenced by water supply system and mining activities. The volume of the reservoir at a water surface area of 117.20 ha was shown to be 4718364 m3 , 1.63% larger, compared to the values 4642640 m3 and 120.75 ha presented in the management manual for the waterwork. The volumes are comparable which indicates that there is no significant amount of siltation and the reservoir became a naturally functional and sustainable ecosystem.
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Effect of exchanger fouling and heat transfer coefficient
Konopiský, Karel ; Kracík, Petr (referee) ; Baláš, Marek (advisor)
This diploma thesis covers the influence of fouling in heat exchangers and heat transfer coefficient. In the first part of the thesis are covered the characteristics of fouling and its formation, process, and effects on heat transfer surfaces in exchangers. In the next part of the thesis, chemical analysis of cooling water is performed on an extracted sample and the potential of fouling is determined based on the analysis. In the conclusion part, computational models of fouling in the tube side of the heat exchanger are presented; fouling of an actual heat exchanger is calculated and compared with data captured during the operation of the heat exchanger.
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