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Assessment of evaporator integration into biogas plant
Peťovský, Patrik ; Touš, Michal (referee) ; Máša, Vítězslav (advisor)
The main waste output of the biogas plant is digested which is used as fertilizer. It can be further process. Digestate cannot be discharged freely into surface waters. This problem is associated with high transportation costs and higher costs of storage tanks in the new biogas plant. The aim of this bachelor thesis is to assess a suitable evaporation system for a particular biogas plant. The evaporation system leads to the concentration of digestate by evaporation water. The system uses heat produced by cogeneration unit. The main consequence of the integration is lower cost for the transport of liquid digestate. The output of the bachelor thesis is a technical and economic evaluation that assesses the payback period depending on the flow of concentrated digestate. The specific costs for adjustment of liquid digestate with regard to the payback period are in the range of 5–15 years. The values do not exceed 210 (Kčyear)/t_fug . The values considering selling heat are even negative. The minimum value guaranteed by the manufacturer is around 260 (Kčyear)/t_fug . The integration of the evaporation system into Žamberk's biogas plant is economically disadvantageous. The thesis brings new knowledge about the potential of multi-stage flash evaporation in biogas plants with short transport distances and high utilization of waste heat.
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Foaming of fermentation residues during a vacuum evaporation
Knob, Jan ; Brummer, Vladimír (referee) ; Vondra, Marek (advisor)
The diploma thesis deals with the processing of digestate, which is the remaining material after biogas production. It aims to experimentally prove how chosen operational parameters of antifoaming agents influence digestate foaming associated with the vacuum evaporating technology. Based on the research of available antifoamers and the issue of digestate foaming itself, it was observed how three selected antifoamers (i.e. rapeseed oil, silicone antifoamer Erbslöh Schaum-ex and oleic acid), together with the decrease in the pH factor of the evaporating digestate, influence the final foam production. For the purposes of the research, an apparatus simulating the vacuum evaporating process was set up in which the heated sample was brought to boil by gradual pressure decrease. The process of foaming was observed in a transparent cylinder of a testing culumn. The essential part of the experimental activity is represented by a planned experiment which by means of a DoE (Design of experiments) method proved rapeseed oil to be very efficient. In contrast, other antifoamers, as well as the influence of the pH factor decrease, manifested themselves as insignificant factors, while the oleic acid even supported the foaming. The supplementary measurements led to a more detailed research of the effects of rapeseed oil and to the construction of a mathematical model describing how the concentration of rapeseed oil undermines the amount of generated foam. The main contribution of the thesis is firstly the evidence that rapeseed oil plays an important part in the reduction process of digestate foaming and secondly the determination of minimum substance concentration leading to the foaming reduction of a particular sample which is considered efficient enough to enable functioning of a vacuum evaporator. The thesis has also experimentally demonstrated the influence of some polymer organic flocculants which have been proved to support the foaming.
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OPTIMIZATION OF WELLNESS AIR CONDITION
Kysilka, Michal ; Zubíček, Vojtěch (referee) ; Šikula, Ondřej (advisor)
The theme of diploma thesis is a design optimization of air distribution in swimming-pool hall with regard to free water surface evaporation. This problem was solved according to determined criterions with the aid of CFD simulation. Experimental measurement part of the thesis deals with evaporation problems where own formula for this physical phenomenon is determined. This formula is compared with already known algorithms. Author suggests that such formula might be integrated in CFD software.
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Equipment for Thickening Waste Water from Biogas Plants
Vondra, Marek ; Bébar, Ladislav (referee) ; Hoffman,, Pavel (referee) ; Stehlík, Petr (advisor)
This dissertation thesis deals with the development of technology which could tackle two major issues related to biogas plants. These issues concern the insufficient use of waste heat from biogas combustion and its subsequent processing. It also concerns the use of the fermentation residues which are formed in large quantities and whose use is restricted by law. Based on a literary search of separation methods, a vacuum evaporator was selected as the most suitable technology. Its advantages include its simple construction, operational reliability and robustness, low costs of thickening medium pre-treatment, potential for a quick commercial application and, especially, the chance to use a low-potential waste heat. A primary purpose of this technological unit is the reduction in the volume of fermentation residues. Other benefits include the efficient use of waste heat from a biogas plant, which would otherwise be wasted. Evaporators with a low consumption of electrical energy (which is a main product of a biogas plant) seem to be the best option for applications in the biogas plants. Three of these technologies were subjected to a more thorough analysis, which included the development of computational models and their quantification for conditions in a sample biogas plant. A one-stage evaporator with a forced circulation (680 – 712 kWhth/m3, 25.9 – 30.5 kWhel/m3) was evaluated as the least suitable option in terms of energy demands. The energy intensity of a three-stage evaporator with a falling film (241 – 319 kWhth/m3, 12.0 – 23.6 kWhel/m3) and a nine-stage flash evaporator (236 – 268 kWhth/m3, 13.6 – 18.4 kWhel/m3) is significantly lower. A multi-stage flash evaporator (MSF) was then chosen for development and will form the central focus of this thesis. The reasons for the choice are as follows: the low requirements on the heat transfer surface, good operational experience in the field of desalination, its simple construction, modularity and evaporation outside the heat transfer surface. A thorough technical-economic evaluation was also performed on the integration of the evaporator into the biogas plant. The main part of the work included the experimental development of a MSF evaporator prototype. The main objective of this development was to achieve a stable flow rate of the thickening liquid digestate fraction and the continuous formation of the distillate. This was not an easy objective to achieve, especially due to the properties of the liquid digestate, which has a non-newtonian characteristic and increased density and viscosity compared to water. The tendency of the liquid digestate to form foam was also the subject of analysis. The development of the evaporator and first successful operational test are described in the thesis in detail. This required the use of an anti-foaming product. A fully-developed prototype of the MSF evaporator allowed us to achieve continuous operation with a distillate production, reaching from 5 to 10 kg/h at a liquid digestate flow rate of 0.4–0.5 m3/h. The main drawback of this technology is the pollution of the distillate with ammonia nitrogen, and it is for this reason that the basic procedures of its subsequent elimination was selected for further analysis.
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Zero liquid discharge systems
Štylárková, Petra ; Máša, Vítězslav (referee) ; Touš, Michal (advisor)
The bachelor thesis contains a description of zero liquid discharge systems. It describes the process, which has three main parts, it is pretreatment, preconcentration and evaporation. In each parts there is a basic description of the principle of the metod, their use etc.
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Nutrients recovery by processing liquid digestate
Štylárková, Petra ; Vondra, Marek (referee) ; Touš, Michal (advisor)
Biogas plants produce a large amount of digestate or liquid digestate annually, which can be further processed to obtain nutrients. This method is not widespread due to high investment costs. In this paper, technologies for nutrient recovery from liquid digestate as well as a techno-economic model are presented. This model was developed using information from literature and calculations in a process simulator. It is able to calculate the overall balance of the system from the input parameters and to tentatively assess the economic evaluation. The use of the model was demonstrated with a case study of a specific biogas plant. The analysis of the effects of the price parameters showed, among other things, that for the biogas plant in question the sensitivity of the return to a lower price of ammonium sulphate (product) is high, while in the case of struvite (product) even at its low price there is no such sensitivity.
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Possibility of using EMW radiation for killing biotic pests
Gintar, Jan ; Klečka,, Tomáš (referee) ; Pěnčík, Jan (referee) ; Šuhajda, Karel (advisor)
The remediation of building elements and structures in terms of moisture and sterilization (inactivation) of biotic pests is dealt with quite often in construction practice and in the construction industry itself, and is thus a topical issue. The issue is dealt with by specialized companies that know the use of available technology on the market, or are themselves involved in the development and improvement of these devices. Several methods are known for the removal of moisture and sterilization of biotic pests, with sufficiently high-quality data on the technology used, the suitability of the equipment used, a more detailed description of the application of the methods themselves and the results themselves. The methods themselves, for removing moisture and eliminating (inactivating) biotic pests, must be chosen according to individual requirements, as some methods will be more appropriate (more effective) and some less suitable. For the practice itself, however, it is important that the methods are sufficiently effective and at the same time available to the wider public (their economic side). In my dissertation thesis I focus on the potential of EMW radiation utilization not only for liquidation of biotic pests (fungi, fungi, wood decaying insects), but also elimination or reduction of necessary conditions for survival or development of these biotic pests. Therefore, my work also focuses on the presence of moisture, because moisture is a common factor in the vast majority of problems associated with the occurrence of biotic pests. Due to its intensity, it is one of the less time-consuming method and therefore a more cost-effective (economically) method. The research I conducted at VUT FAST focused on the use of microwave radiation in the control of biotic pests, under conditions that are close to those on real constructions. The use of a microwave method to eliminate biotic pests and at the same time to remove moisture has proved to be advantageous.
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Zero liquid discharge systems
Štylárková, Petra ; Máša, Vítězslav (referee) ; Touš, Michal (advisor)
The bachelor thesis contains a description of zero liquid discharge systems. It describes the process, which has three main parts, it is pretreatment, preconcentration and evaporation. In each parts there is a basic description of the principle of the metod, their use etc.
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Assessment of evaporator integration into biogas plant
Peťovský, Patrik ; Touš, Michal (referee) ; Máša, Vítězslav (advisor)
The main waste output of the biogas plant is digested which is used as fertilizer. It can be further process. Digestate cannot be discharged freely into surface waters. This problem is associated with high transportation costs and higher costs of storage tanks in the new biogas plant. The aim of this bachelor thesis is to assess a suitable evaporation system for a particular biogas plant. The evaporation system leads to the concentration of digestate by evaporation water. The system uses heat produced by cogeneration unit. The main consequence of the integration is lower cost for the transport of liquid digestate. The output of the bachelor thesis is a technical and economic evaluation that assesses the payback period depending on the flow of concentrated digestate. The specific costs for adjustment of liquid digestate with regard to the payback period are in the range of 5–15 years. The values do not exceed 210 (Kčyear)/t_fug . The values considering selling heat are even negative. The minimum value guaranteed by the manufacturer is around 260 (Kčyear)/t_fug . The integration of the evaporation system into Žamberk's biogas plant is economically disadvantageous. The thesis brings new knowledge about the potential of multi-stage flash evaporation in biogas plants with short transport distances and high utilization of waste heat.
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