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Sewage sludge treatment
Adamus, Petr ; Havlásek, Martin (referee) ; Zejda, Vojtěch (advisor)
The first part of bachelor’s thesis deals with waste water treatment up to the phase, when the sewage sludge is created. Then follows the summary of available sludge treatment and disposal methods and their description. Next part is about legislative overview and a summary of the limits imposed on waste water treatment plants. In the last part, the bachelor thesis deals with description of sludge properties and their measurement methods. The practical part contains measurement and calculation of sewage sludge properties, exactly calculation of dry matter by determination of dry residue and determination of loss on ignition in sludge.
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Upgrading biogas by PSA
Krhut, Štěpán ; Havlásek, Martin (referee) ; Zejda, Vojtěch (advisor)
This work deals with bio gas cleaning by a PSA method and modernizing of a laboratory unit. Raw bio gas contains many unwanted elements like carbon dioxide mostly which lowers its energy potential then. To extend the possibilities of usage of bio gas it is necessary to remove such elements. One of the well-known method for eliminating CO2 out of the bio gas is the method called Pressure Swing Adsorption (PSA). This work describes PSA method and compares it with other methods for cleaning the bio gas. In the following part of my work I am introducing the original laboratory PSA unit which is placed in the laboratory of UPI institution for research purposes. The modernization of the method was made by changing the manual valves for electromagnetic ones and there was also designed a new control system unit for two control modes. For manual and for automatic. The essential function is based on remote controlling the valves either by switches or by a program. The electric control panel was created for such required modes. The automated process was controlled by Arduino programming platform which was integrated into the panel. In the case of the next measurement and reading there was created a detailed description for user on how to operate the control panel and also the comments for control program of automatization.
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Burning pellets from non-wood biomass in boilers I
Knob, Jan ; Zejda, Vojtěch (referee) ; Brummer, Vladimír (advisor)
This bachelor’s thesis deals with combustion of non-woody biomass pellets in boilers. In the first part of the background research, biomass is generally described in terms of fuel properties, with a focus on characteristics determining its suitability for a direct combustion in boilers and undesirable emissions. In this context, planned legislative restrictions of boilers with a lower operating power are summarized. Furthermore the usage of the automatic boilers, and specific problems associated with combustion of non-woody pellets are described. Final part of the background research focuses on a composition of commercially available non-woody pellets and their production. Experimental part consists of fuel analysis determining the general properties of the biofuel - i.e. the water and ash content, essential content of elements, lower and higher heating values. Results of analysis are used to put together fuel lists of tested pellets. Conclusion of the experimental part discusses the influence of the pellet composition on the boiler functionality and emissions.
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Characteristic parameters of fuel nozzles
Ledererová, Lucie ; Zejda, Vojtěch (referee) ; Bělohradský, Petr (advisor)
Many industrial applications acquire necessary thermal energy through the combustion process. The basic element of each combustion appliance is a burner and one~part~of~it~is a~nozzle system that supplies fuel to a combustion chamber. The geometry of the fuel nozzle significantly affects the intensity of mixing the fuel with the combustion air and thus the stability of the combustion. The main subject of~this diploma thesis is~determination of~velocity coefficients for nozzles with different geometries. The knowledge of~correct values of~velocity coefficients is a key parameter for the design of~the burner and~its subsequent operation. For the calculation of~velocity coefficients, the exit nozzle velocities were used. For chosen nozzles, a~theoretical exit nozzle velocities were calculated. They were compared with the actual exit nozzle velocities, which were measured experimentally using the hot-wire anemometry, and with velocities, which were calculated using the CFD simulation method.
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Ejectors and it's utilization in industry
Zejda, Vojtěch ; Hájek, Jiří (referee) ; Vondál, Jiří (advisor)
This work aims at introducing ejector pumps. It describes the working principle, advantages and disadvantages and restrictions of their usage in various applications. Main disadvantage of ejectors is the low efficiency which limits the usage only in specific applications where it is not considered to be a crucial factor. Therefore, examples of usage of various ejectors in industrial processes are listed further. Last but not least, in these examples are also demonstrated difficulties and reasons why it is favourable to use an ejector rather than other types of pumps. Further off, this work deals with design methods of ejectors and compares their suitability. It appears that not all the methods are suitable for ejector design, because it depends greatly on presumed shape of a certain ejector. In the end, there is compared energy intensity of an ejectors and common centrifugal pumps and confirms energy disadvantage of ejectors.
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Velocity profile measurement downstream of swirler
Zejda, Vojtěch ; Hájek, Jiří (referee) ; Vondál, Jiří (advisor)
A burner is very important device in process furnaces that significantly affect the production of emissions during the combustion process. One of the key things in development of the modern low-NOX burners is the evaluation of flow field downstream of an axial blade swirler inside the burner. The computational fluid dynamics (CFD) is often used to predict the attributes of the flow. Predicted values should be validated with measurement. It is the reason why the velocity fields for several choosen swirlers were measured. The hot wire anemometry was choosen and the dual-sensor probe was used during the measurement. The data can be then used for CFD validation. This thesis describes procedure of measurement set-up. The experimental facility was designed according to the anemometry method. The new probe traversing system was designed, which provides desired accuracy. Five different swirlers were measured. Large data set, need for customized post-processing and control over calculation procedures lead to new software design. For each swirler the velocity profiles were gathered and the swirl numbers calculated. That final data were transferred in to graphical format. Uncertainty of measured data was calculated. Results show counter-rotating flow in some areas closed to the swirler. Some drawbacks of current measurement set-up are discussed. Based on the thesis reader can obtain the information and knowledge for consequent measurements of swirl burners velocity profiles.
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Design of optimal mixing of large-scale digesters
Bradáč, Antonín ; Bělohradský, Petr (referee) ; Zejda, Vojtěch (advisor)
The aim of this diploma thesis is an optimal method of mixing of the digester with consideration to the uniform mixing of the whole volume, ensuring the quality process conditions for the anaerobic fermentation and the maximum yield and quality of the produced biogas. First chapters describe the basic design parameters, general calculations and the principles for design of individual types of mixers, supplemented by practical examples of mixing large capacity tanks. The work introduces the problem of sludge formation at the sewage treatment plant with an emphasis on sludge treatment and the processes which take place inside the fermenter. Various types of design of anaerobic sludge stabilization digester were introduced. Also ways of their operation, which are necessary for the quality of the fermentation, were presented. In the next chapters, various ways of mixing high-capacity digester tanks and experience from the operation of selected treatment plants were described. According to the theoretical research part of this thesis, several types of mixing equipment was designed for the experimental digestion tank built at the Institute of Process Engineering which is used for research work with mixers. Measurement of the selected pneumatic mixing method was performed on the experimental tank and the findings were evaluated.
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Waste heat recovery from processes using heat pumps
Marada, Petr ; Zejda, Vojtěch (referee) ; Havlásek, Martin (advisor)
The aim of the bachelor thesis is to describe the possibilities of using waste heat from the processes by heat pumps. The first part defines the waste heat and deals with the possibilities and ways of its use. The next section describes the different types of heat pumps, their components and sources from which it is possible to draw the heat. The last part shows the calculation of return on investment to make heat pump for heating office buildings.
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The Influence of the fuel used in the burner for heat transfer in process furnaces
Jaworská, Petra ; Zejda, Vojtěch (referee) ; Skryja, Pavel (advisor)
This diploma thesis is about an influence of technical gases CO2 and N2, that are present in a fuel, over overall combustion process and a flue gas emissions. The first part of this thesis discussed issues like heat transfer, basic process combustion utilities, used technical gases in experimental part and finally description of observed pollutants. Second part of thesis describes the experiments themselves. Experiments were trying to find how selected parameters were influenced by adding 40 mN3/h or 80 mN3/h of inert gases to a flow of natural gas. Observed parameters were namely emission volumes, flame parameters and maximal heat duty. Experiments took place in horizontal water-cooled combustion chamber and were performed on two different types of burners. Evaluation of results confirmed clear connection of inert gases on temperature of flame; the biggest temperature drop was observed while inert gas CO2 was present in fuel. Lowering of temperature spikes also highly influenced presence of NOx in hot flue gas during all performed trials.
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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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