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Characteristics of gels used in the fluids engineering
Hudák, Igor ; Habán, Vladimír (referee) ; Fialová, Simona (advisor)
Not only in common life, but also in the technical area the usage of gels presents some kind of standard. Gels offer a unique possibility of usage in numerous areas. The gel structure itself is a very interesting material however it’s hard to specify its characteristics. The gel system presents a huge macromolecular network which enables to observe its different characteristics in comparison to other materials. In some circumstances gels act almost as conventional materials, in other circumstances, however, they act significantly otherwise. Therefore this bachelor thesis deals with a description and summarization of single characteristics of gels in chosen branches of the mechanical engineering industry where gels are used on a daily basis, such as sealant of pipeline systems, wires or electronic components. The thesis also describes principles of gel formation, with the emphasis to building of gel substance and with respect to its mechanical and physical features. In the end, the thesis gives a comparison of chosen characteristics of gels that are used as sealants and gels that are used for encapsulation of electrical set.
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Influence of Inert Gases on Characteristic Parameters of Combustion Process
Hudák, Igor ; Jegla, Zdeněk (referee) ; Odstrčil, Miloslav (referee) ; Hájek, Jiří (advisor)
The dissertation thesis is focused on the investigation of the influence of inert gases on characteristic parameters of the combustion process. Inert gases are usually standard components of alternative gaseous fuels such as the producer gas, coal gas or biogas. For a long period some of the fuels were considered as waste gases and their potential was not sufficiently utilised. Compared with noble fuels such as natural gas, alternative fuels have different physical-chemical properties. For example, their lower heating value (LHV) can be lower even than 10 MJ/mN3. The composition of the alternative gaseous fuels can be various during their production process. Lower LHV is a result of the occurrence of inert gases that does not take a part in the combustion reactions. Inert gases have the ability to accumulate the heat. Under certain conditions it is possible to combust alternative fuels on conventional burners, but due to their different properties, problems can occur during the combustion. E.g. to achieve the same heat output as with the noble fuel, it is necessary to burn bigger volume of the alternative fuel. However, the limiting factor could be the burner's head geometry. Theoretical introduction of the thesis summarizes research results in the field of low calorific gaseous fuels combustion and the addition of inert gases into the noble fuels. The thesis also describes the mechanisms of the NOx formation and summarizes techniques which can be used to reduce NOx formation. Furthermore, fuels from alternative sources are categorized and described, including their composition and characteristics. Their physical-chemical properties were obtained by means of the combustion simulation carried out in the simulation software. Two devices had to be designed and manufactured to fulfil goals of the dissertation thesis. The first is a gas mixing station capable of mixing 4 different components. The second device is a burner utilized for the combustion of low calorific fuels. The key section of this thesis is a chapter describing the experimental plan, the performance and the evaluation of the experiments. The goal of the experiments was to dilute the natural gas by two inert gases, namely carbon dioxide and nitrogen. The lowest LHV value achieved during the experiment was 10,7 MJ/mN3. The influence of the inert gases on the NOx emissions, the flame stability and characteristics, the flue gas temperature, the in-flame temperatures, the heat flux and the thermal efficiency was investigated and evaluated. Each parameter was measured and evaluated for three different burners: the burner with the staged gas, the burner with the staged air and the burner for low calorific fuels. Generally, after the addition of the inert gas into the noble fuel, the in-flame temperatures decreased. As a consequence, the NOx emissions decreased as well. The effects of carbon dioxide on the investigated combustion parameters were more substantial than the effects of nitrogen. Each measured parameter is strongly dependent on the burner geometry. The experiments revealed that in most cases the addition of the inert gas into the fuel influenced the flame length (flame shortened) and also more heat was transfered into the chamber's walls closer to the burner tile.
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Methods for the reduction of nitrogen oxides
Šimeček, Radek ; Hudák, Igor (referee) ; Bělohradský, Petr (advisor)
This Bachelor’s thesis deals with methods for the reduction of nitrogen oxides during industrial combustion. In the chapter relating to legislation are summed up the limits for stationary sources of pollution valid in the Czech Republic, further are stated the legislative tools for reducing and monitoring emissions. The next part contains an overview of primary and secondary methods for reducing NOx emissions, including pros and cons of the methods. Finally, a simulation in software ChemCAD is carried out, demonstrating the influence of combustion air temperature and flue gas recirculation on parameters of combustion.
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The influence of operating parameters and construction parameters of the low-NOx burner on characteristic parameters of combustion processes
Nykodým, Jiří ; Hudák, Igor (referee) ; Bělohradský, Petr (advisor)
The main aim of the work was the investigation of the effect of operational parameters of the combustion process (combustion air excess, primary fuel ratio) and burner constructional parameters (the pitch angle of secondary nozzles, tangential orientation of secondary nozzles towards the axis of the burner) on the formation of NOx and CO, flue gas temperature, the shape, dimensions and stability of the flame, in-flame temperatures in the horizontal symmetry plane of the combustion chamber and the amount of heat extracted from the hot combustion gases in the combustion chamber’s shell. Experimental activities were carried out in the laboratory of the Institute of Process and Environmental Engineering, which is focused on burners testing. The combustion tests were performed with the experimental low-NOx type burner, namely the two-gas-staged burner. Mathematical model developed based on the experimental data describes the dependency of NOx on the operating parameters of the combustion process and burner constructional parameters. The model shows that increasing air excess and increasing angle of tangential orientation of the secondary nozzles reduce the formation of NOx. The temperature peaks in the horizontal symmetry plane of the combustion chamber decreases with increasing combustion air excess. The thermal load to the combustion chamber’s wall along the length of the flame was evaluated for selected settings. It was validated that the thermal efficiency of is reduced when higher air excess is used.
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Air enrichment with highly pure oxygen in combustion processes
Polášek, Kryštof ; Hudák, Igor (referee) ; Bělohradský, Petr (advisor)
This bachelor thesis deals with the oxygen enhanced combustion (OEC). The thesis describes different methods of enriching the combustion process with oxygen, also the advantages and disadvantages of enhancing the combustion are evaluated. The next part contains an overview of the use of OEC in specific industries. Since certain safety precautions must be taken when handling of oxygen, a separate chapter deals with the safety of oxygen enhanced combustion. In the last part of the thesis a simulation of the OEC process in ChemCAD software was carried out. The influence of oxygen concentration in the oxidizing agent on the flue gas volume, temperature, density and viscosity and the concentration of CO2 and H2O in the flue gas was investigated.
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Characteristic parameters of oxygen-enhanced combustion process
Hudák, Igor ; Hájek, Zdeněk (referee) ; Bělohradský, Petr (advisor)
Diplomová práce se zabývá spalováním zemního plynu při využití vzduchu s vyšším obsahem kyslíku (21–46 % kyslíku ve spalovacím vzduchu), tzv. kyslíkem obohaceným spalováním (OEC). Technologie OEC nalezla uplatnění v průmyslu, kde se jsou nároky na zvýšenou produktivitu, dosažení vyšší tepelné účinnosti, zlepšení vlastností plamene, snížení náklady, či zlepšení kvality výsledného produktu. Ačkoliv OEC přináší řadu výhod, je nutné zmínit i nevýhody jako: poškození zařízení, nestejnoměrné zahřívání, narušení plamene, zvýšené emise anebo zpětný zášleh plamene. Zkoušky proběhly na zkušebně hořáků, která umožňuje testovat hořáky nejen na plynná a kapalná paliva, ale i hořáky navržené pro kombinované spalování při maximálním výkonu hořáku 1 800 kW. Při zkouškách byl použit plynový „low-NOx“ hořák se stupňovitým přívodem paliva. V diplomové práci je popsán vliv obsahu kyslíku ve spalovacím vzduchu na emise oxidů dusíku (NOx), teplotu plamene, přenos tepla ze spalin do stěn spalovací komory, a také vlastnosti plamene, zvláště pak jeho stabilitu, tvar a rozměry. Zkoušky proběhly při výkonech 300 kW, 500 kW a 750 kW, přičemž pro výkon 750 kW proběhly testy jak při jednostupňové, tak dvoustupňové konfiguraci.
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Rotary drying and sintering kilns
Rafaj, Svatomír ; Hudák, Igor (referee) ; Skryja, Pavel (advisor)
This thesis deals with rotary drying and sintering kilns. The first part focused upon construction of the kilns, kiln processes and the options of technological arrangement of the kilns. The thesis second part presents two experiments. The first one is targeted to find the relation between residence time, kiln rotary speed and kiln slope in longitudinal direction. The examinations analysed individually the relation between kiln rotary speed and residence time and the relation between kiln slope and residence time. Finally, the regression equation describing the relation between holding time, kiln rotary speed and kiln rake was established. The results given by regression equation much closer to the real one then the results given by literature. The difference between real residence time and the regression one is about one minute. The second one is concerned with producing a set of equations with respect of mass and heat balance in case of drying process. The input material was wet crushed tetra packs. There were established technological conditions of the material, necessary burner energy input, heat losses and distribution of heat between material and flue gas. There were taken away almost 80 percent of heat energy by flue gases. The remaining 20 percent was divided between latent heat, material and heat losses through the shell of the rotary kiln.
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The use of fuels from renewable sources and waste
Pořízek, Vít ; Hudák, Igor (referee) ; Skryja, Pavel (advisor)
The main theme of this thesis is available and potential gaseous and liquid alternative biofuels made from biomass and waste. The thesis deals with their detailed description and comparison. The first part covers the basic distribution of biofuels and alternative fuels made from waste. The main part focuses then on the fuels themselves, their properties, production, use and environmental impact. Furthermore, thesis describes legislative issues and fuels are compared from different perspectives. Practical part includes testing of combustion of liquid fuels taken from waste sources. In the next chapters there is executed overview of basic atomization method of liquid fuels and a plan and running of the testing processed. Evaluation of results is based on point of view of suitability for use, the quality of combustion and emission limits.
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Hemp as an alternative fuel
Jaworská, Petra ; Zejda, Vojtěch (referee) ; Hudák, Igor (advisor)
Bachelor thesis as literary research deals with possibilities of using hemp as an energy crop and its development and sustainability in the future. Production of hemp bio-fuels in Czech Republic is in the beginning but increasing interest in alternative energy sources presumes development in this branch. Producing bio-fuels made of hemp biomass brings many positive benefits in liquid, gas or solid states. Liquid biodiesel made of hemp presents alternative source of energy that can be used in common diesel engines. Hemp hurds briquettes are the most used hemp fuel in our country. Hemp briquettes has perfect properties in comparison to other sources. High heat of combustion, low purchase price and environmental friendliness gives motivation to create new growing branches. Second most common use is biogas fuel. Biogas is produced in usual biofermenter using hemp biomass often with admixture of slurry. Hemp biogas properties are also very satisfactory. In Czech Republic is huge potential in development and production of hemp biogas due to large number of biogas plants. Despite financially demanding processing of the hemp biomass the amount of biomass grow during one year makes this plant one of the most profitable alternative source for production of bio-fuels.
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The influence of the combustion air temperature on parameters of the combustion process
Šimeček, Radek ; Hudák, Igor (referee) ; Skryja, Pavel (advisor)
Tato diplomová práce se zabývá předehřevem spalovacího vzduchu a jeho vlivem na parametry spalovacího procesu. V teoretické části je zpracován přehled nejčastějších znečišťujících látek z průmyslového spalování. Je popsána aktuálně platná relevantní legislativa v Evropské unii a jsou porovnány její implementace do národní legislativy v České republice a v Německu. Dále je provedena klasifikace hořáků z hlediska různých kritérií a rešerše předchozí práce v oblasti předehřevu spalovacího vzduchu. Na zkušebně hořáků byla provedena experimentální studie dvou různých hořáků na zemní plyn při konstantním tepelném příkonu 750 kW se spalovacím vzduchem předehřátým až na 250 °C. Výsledky odhalily pozitivní vliv předehřevu na účinnost spalování. Množství emisí NOx a CO naopak rostlo s teplotou spalovacího vzduchu.
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