The master thesis deals with design of storage tank for nitric acid. The first chapter introduces the problems of design, manufacture and operation of the storage tanks. The next section describes design calculation of storage tank according to standard EN 14015. Control of design calculation is performed by analysis FEM in program ANSYS Workbench 16.2. Thesis also includes basic drawing of storage tank.

Master of Science

<div>The author aims to investigate the current design provision for seismic and foundation settlement design of aboveground open-top storage tanks using finite element analysis. The thesis is divided into two independent but closely related studies: (1) seismic analysis of open-top storage tanks with flexible foundation and (2) fitness-for-service of open-top storage tanks subjected to differential settlement.</div><div><br></div><div>The present seismic design provisions in American Petroleum Institute’s storage tank standard API 650 (2013) assumes the tank foundation is rigid and therefore, ignores the effect of uplift during a seismic excitation. In the first study, the objective was to quantitatively critique rigid foundation assumption and conclude if the assumption is acceptable or not for a given tank geometry. Tanks with three different height to diameter ratio (H/D), i.e aspect ratios, of 0.67, 1.0 and 3.0 representing broad, nominal and slender geometry, respectively, were modelled having both rigid and flexible foundations. The flexible foundation was modelled with series of non-linear compression only springs. Additionally, for each tank model two different hydrodynamic pressure distribution suggested by (1) Housner and (2) Jacobsen-Veletsos were applied which are used by API 650 and Eurocode 8, respectively. Geometric non-linear analysis with non-linear material properties was conducted (GMNA) using Riks algorithm in Abaqus finite element analysis (FEA) program. The hoop stresses, longitudinal stresses, uplift and buckling capacity of each rigid foundation tank model were compared with its respective flexible foundation tank model and corresponding API 650 rule based provisions. It was observed that the assumption of rigid foundation from design point of view is acceptable for the broad tank, however, for the nominal and slender tanks this assumption is not acceptable. The buckling capacity of nominal and slender tanks having flexible foundation are significantly lower compared to rigid foundation. Therefore, the effect of uplift should not be neglected for design purposes for nominal and slender tank geometries.</div><div><br></div><div>In the second study, an alternative method for evaluating the structural integrity of storage tank subjected to differential settlement is proposed. The limitations of the existing method in API 653 (2014), currently used in the industry are highlighted. The tank settlement is measured underneath</div><div>12</div><div>the tank bottom along the tank circumference at discrete locations. The settlement can be transformed into a Fourier series by combining different harmonic components. In the existing API 653 method there is no distinction between the effects of different harmonic components whereas in the proposed method the effects of first five harmonic components are individually accounted and the cumulative damage is evaluated. The proposed method is formulated based on FEA conducted on twenty-one different tank models with each having different tank geometry. The limiting settlement value for each harmonic wave number is found for a given tank geometry by conducting GMNA using Riks algorithm, and a generalized trend is found for each harmonic wave number. The proposed method is further validated by performing numerous FEA simulations. The simulations were conducted for several tank models subjected to four representative actual measured settlement data. A set of tank models used in the validation was generated using random tank geometries and design parameters to have a blind test of the proposed method. Finally, a comparison is made between allowable settlement based on the API 653 method, the proposed method and the FEA. It was observed that the proposed method consistently results in conservative results compared to FEA. In contrast the API 653 method does not always result in conservative results. For some measured settlement data, the API 653 method gives overly conservative values and for others it gives non-conservative values. Moreover, the API 653 method is based on the beam theory which may not capture the true shell behavior. Therefore, the API 653 method requires modifications. The proposed method on the other hand is consistent and is based FEA which can capture the true shell behavior as it is formulated using shell theory. Therefore, it is recommended that the existing method in API 653 shall be replaced with the proposed method to determine the fitness of tank under differential settlement.</div>

Orientador: Marcelo da Costa Ferreira / Resumo: O algodão (Gossypium hirsutum L.) tem grande relevância para a economia mundial. Dentre os principiais fatores limitantes da produção estão os problemas fitossanitários, que ocorrem em todas as fases da cultura. O inseto Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) é importante devido a sua capacidade de causar danos nas folhas e maçãs do algodoeiro, muitas vezes requerendo a aplicação frequente de inseticidas para o seu controle. Em geral são utilizados inseticidas químicos. Entretanto, o uso de bioinseticidas têm aumentado consistentemente, principalmente aqueles à base de Bacillus thuringiensis, chamados de Bt bioinseticidas. Fatores abióticos como a chuva também interferem na eficiência de aplicações de Bt bioinseticidas e consequentemente no controle do organismo alvo. Uma alternativa que pode dar proteção ao Bt mediante chuva é a adição de adjuvantes a calda. Porém, pouco se sabe o quanto a associação do Bt com adjuvantes afeta no crescimento vegetativo, esporulação e persistência da bactéria e o controle. Portanto é de extrema importância à compreensão das interações físico-químicas e biológicas da mistura de Bt bioinseticidas e adjuvantes. Neste contexto, objetivou-se avaliar o efeito da adição de adjuvantes nas características físico-química e biológicas dos Bt bioinseticidas nas formulações Dipel® WP e Dipel® SC submetidas à chuva artificial para o controle de S. frugiperda em plantas de algodão. Para simular a chuva, foram utilizadas as lâminas de chuv... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Cotton (Gossypium hirsutum L.) has great relevance to the world economy. Among the main limiting factors of production are the phytosanitary problems that occur at all stages of the crop. The insect Spodoptera frugiperda (JE Smith) (Lepidoptera: Noctuidae) is important because of its ability to cause damage to cotton leaves and apples, often requiring insecticides to be applied frequently for its control. In general, chemical insecticides are used. However, the use of bioinsecticides has consistently increased, especially those based on Bacillus thuringiensis, called Bt bioinsecticides. Abiotic factors such as rain also interfere with the efficiency of Bt applications and consequently in the control of the target organism. An alternative that can protect Bt in the rain is the addition of adjuvants to the syrup. However, little is known about how the association of Bt with adjuvants affects vegetative growth, sporulation and bacterial persistence and control. Therefore, it is extremely important to understand the physicochemical and biological interactions of the mixture of Bt bioinsecticides and adjuvants. In this context, the objective of this study was to evaluate the effect of the addition of adjuvants on the physicochemical and biological characteristics of Bt bioinsecticides in the formulations Dipel® WP and Dipel® SC submitted to artificial rain to control S. frugiperda in cotton plants. To simulate the rain, the 20mm artificial rain blades applied one hour after the ap... (Complete abstract click electronic access below) / Doutor

In order to increase the efficiency of an adsorption heat pump system, a stratified thermal heat storage can be used to enable regeneration of heat between the different phases of the process. It’s crucial to avoid mixing and to keep layers intact inside the storage tank. As mixing generally occurs during charging and discharging, the aim of this project is minimizing these effects by introducing porous media into the region of the inlet ports. The impact of porous media on laminar and turbulent flow inside stratified thermal storage tanks is qualitatively and quantitatively investigated. Two thermal storage tanks are examined in which polyurethane foam is used as porous medium. Numerical results are compared with experimental results in order to study the effects of the porous medium and validating numerical models. For the quantitative investigation, equations describing flow in porous media are obtained and implemented into computational fluid dynamics (CFD) models. Simulations of storage tanks are performed by means of 2D-axisymmetric domain models. Tanks are investigated qualitatively using two methods; background oriented schlieren (BOS) and ink colored inlet water, in order to visualize flow and mixing inside tanks. Thermo elements are also used to measure temperatures at given locations. Results from experimental- and numerical cases show how porous media influence stratification in a positive way. Flow visualizing experiments (using ink and BOS) showed decrease in thermocline thickness when using polyurethane foam. This could also be seen for the numerical cases. Experimental- and numerical investigations of the ability of porous media to damp turbulence intensity and kinetic energy, showed a positive effect. Further improvements have to be done, adjusting numerical models to experimental results. Comparison between the numerical- and experimental results showed differences both in flow fields and temperature distributions. Results indicate however, that porous media could play an increasing role in the development of stratified heat storages. / Stratifierade värmelagringstankar kan användas för att öka effektiviteten hos adsorptionsvärmepumpsprocesser genom att möjliggöra regeneration av värme mellan faserna. För att dessa effektivt ska kunna användas är det viktigt att temperaturskikt hålls intakta inuti lagringstankarna och att omröring undviks. Då omröring oftast uppstår vid laddning och tömning av lagringstankarna är målet för det här projektet att minska denna effekt genom att använda porösa medier vid deras inlopp. Porösa mediers inverkan på flöden och temperaturskikt inuti värmelagringstankar undersöks både kvalitativt och kvantitativt i det här projektet. Två tankar undersöks där polyuretanskum används som poröst medium. Numeriska resultat jämförs med experimentella för att undersöka effekterna av de porösa medierna, samt för att validera de numeriska modeller som används. Ekvationer som beskriver flödet genom porösa medier implementeras i CFD (computational fluid dynamics) modeller och lagringstankarna modelleras som 2D-axelsymmetriska domäner. Bakgrundsorienterad schlierenteknik (BOS) och färgning av inloppsvatten används för den kvalitativa undersökningen och termoelement används för att mäta temperaturer vid olika positioner. Numeriska och experimentella resultat visar hur porösa medier har en positiv inverkan på temperaturskiktningen. Resultat från experiment då BOS teknik och färgning av vatten används visar en minskning av det termoklina skiktets tjocklek med en ökad polyuretanskumtjocklek. Detta kunde också ses för de numeriska fallen. Numeriska och experimentella resultat visar även att porösa medier har en positiv inverkan på dämpningen av turbulens och kinetisk energi. Fortsatt arbete krävs för att anpassa numeriska modeller till experimentella data. Jämförelser mellan numeriska och experimentella resultat uppvisar skillnader både hos flödesfält samt hos temperaturfördelningar inuti tankarna. Resultaten visar dock att porösa medier skulle kunna spela en betydande roll för utvecklingen av stratifierade värmelagringstankar.

With the ongoing trend in moving the upper levels of the automation hierarchy to the cloud, there has been investigation into supplying industrial automation as a cloud based service. There are many practical considerations which pose limitations on the feasibility of the idea. This research investigates some of the requirements which would be needed to implement a platform which would facilitate competition between different controllers which would compete to control a process in real-time. This work considers only the issues relating to implementation of the philosophy from a control theoretic perspective, issues relating to hardware/communications infrastructure and cyber security are beyond the scope of this work. A platform is formulated and all the relevant control requirements of the system are discussed. It is found that in order for such a platform to determine the behaviour of a controller, it would need to simulate the controller on a model of the process over an extended period of time. This would require a measure of the disturbance to be available, or at least an estimate thereof. This therefore increases the complexity of the platform. The practicality of implementing such a platform is discussed in terms of system identification and model/controller maintenance. A model of the surge tank from SibanyeStillwater’s Platinum bulk tailings treatment (BTT) plant, the aim of which is to keep the density of the tank outflow constant while maintaining a steady tank level, was derived, linearised and an input-output controllability analysis performed on the model. Six controllers were developed for the process, including four conventional feedback controllers (decentralised PI, inverse, modified inverse and H¥) and two Model Predictive Controllers (MPC) (one linear and another nonlinear). It was shown that both the inverse based and H¥ controllers fail to control the tank level to set-point in the event of an unmeasured disturbance. The competing concept was successfully illustrated on this process with the linear MPC controller being the most often selected controller, and the overall performance of the plant substantially improved by having access to more advanced control techniques, which is facilitated by the proposed platform. A first appendix presents an investigation into a previously proposed switching philosophy [15] in terms of its ability to determine the best controller, as well as the stability of the switching scheme. It is found that this philosophy cannot provide an accurate measure of controller performance owing to the use of one step ahead predictions to analyse controller behaviour. Owing to this, the philosophy can select an unstable controller when there is a stable, well tuned controller competing to control the process. A second appendix shows that there are cases where overall system performance can be improved through the use of the proposed platform. In the presence of constraints on the rate of change of the inputs, a more aggressive controller is shown to be selected so long as the disturbance or reference changes do not cause the controller to violate these input constraints. This means that switching back to a less aggressive controller is necessary in the event that the controller attempts to violate these constraints. This is demonstrated on a simple first order plant as well as the surge tank process. Overall it is concluded that, while there are practical issues surrounding plant and system identification and model/controller maintenance, it would be possible to implement such a platform which would allow a given plant access to advanced process control solutions without the need for procuring the services of a large vendor. / Dissertation (MEng)--University of Pretoria, 2020. / Electrical, Electronic and Computer Engineering / MEng / Unrestricted

Fuel leakage through a fill limit vent valve (FLVV) inside a fuel tank is an important factor to consider during the design of a new tank. The performance of the carbon canister which absorbs the hydrocarbon can be compromised if fuel manages to escape through the valve, so called Liquid Carry Over (LCO) and thus not fulfilling the fuel emission requirements. As of today this is not thoroughly investigated using experiments nor Computational Fluid Dynamics. The main focus of this study was to develop a method to simulate the behaviour of the FLVV during various driving conditions at an early design stage and if this gives rise to fuel escaping through the FLVV. This method was later to be validated with an experimental set-up and later used to perform some simulations to investigate LCO by varying different parameters such as fuel level and different types of driving. What happens when the canister is purging was also investigated to see if it has a pronounced effect on LCO. Purging is when hydrocarbons, absorbed by the canister, are sent to the engine and giving rise to an under pressure in the tank.The method was developed to run on a cluster utilizing 200 Central Processing Unit Cores where each simulated physical second required an average of 3 hours of simulation time.The flow inside the tank was simulated using a Volume Of Fluid (VOF) multiphase model and the dynamic behaviour of the floater inside the FLVV was simulated using an overset mesh with a Dynamic Fluid Body Interaction.The movement of the simulated dynamic floater was validated with an experimental set-up specifically developed for the overset mesh validation and the motion of the floater was captured at a fairly accurate level.A prototype for an experimental tank was also developed and produced to validate the VOF set-up used for sloshing inside the tank which was utilized on the real tank but due to time limitation the experiments were not performed. The results from the parameter investigation showed that LCO was present in cases with high fuel level inside the tank 95 % and that an aggressive driving gives rise to a higher level of LCO compared to normal driving. Simulations with a fuel level of 85 % and lower showed no evidence of LCO for this particular tank model. The purging of the tank induced a pumping effect giving rise to a higher level of LCO pumped through by the floater.

Abstract Storage tanks are above or below ground vessels for storing chemicals, petroleum and other liquid products. Above ground vertical cylindrical shells are typically thin walled structures prone to buckling and lose their stability especially when they are empty or have lower fluid level due to external loads.According to the Swedish National board of Housing, Building and Planning (Boverket), the Eurocodes and the Swedish national annex and building code for structural design, EKS (BFS 2011:10) should be used for verification of mechanical resistance of storage tanks. However the industry has been using a European design standard EN14015, for design of large site built steel tanks. The research question is if this design fulfils the requirements in the Swedish building code EKS and the Eurocodes. In order to investigate this, a parametric study of the buckling resistance of an empty tank has been performed, by comparing the design according to EN14015 With the requirements according to the Swedish building code and the Eurocodes. The finite element analysis was done with the finite element tool ABAQUS, The parametric study was carried out for three terrain categories0, I and II, for thesix snow load zones and for six basic wind velocities according to the Swedish snow and wind maps in EKS. The buckling resistance also further investigated for three reliability classes, reliability class 1, 2 and 3 according to the Swedish national annex and for two fabrication classes, fabrication class A and B usingEN1991-1-6The finite element analysis result of linear elastic and nonlinear buckling analysis with imperfections showed that, design according to EN14015 can meet the requirements of Eurocodes and EKS at lower basic wind velocities, terrain category (I and II) for smaller imperfections . But it does not meet the requirements at terrain category-0, for all reliability classes and all imperfection classes.The tank shell showed in some cases an increase in the load proportionality factorin nonlinear analysis for the load combinations considered in this study. It is thus necessary to study further on the finite element modelling of thin walled large tanks on relations of local buckling effect due to highly stiffened regions and the effect of magnitudes and applications of imperfections for large tanks using EN1993-1-6

This project aimed to investigate the capability of the STAR CCM+ software when predicting the flow with particles using Lagrangian Particle Tracking and Discrete Element Method. The first part pertained to rectangular channel flow, with ratio between height of the channel and particle diameter (2h/Dp ) of 15. It was found out that simulations of particles in a channel come with many diculties. Such as, obtaining accurate pressure drop results using DEM when comparing to DNS simulations including particles within a reasonable computational time. The second part consisted of a simulation of the off-centred mixing tank. As the use of DEM caused numerical issues, another modeling approach was used. Therefore, the Lagrangian Particle Tracking was used. The outcome of the project is the sensitivity study of the forces which can be applied to the particles. The finding was that the Shear Lift force and the Virtual Mass force have a negligible contribution in regards to the particles distribution. In addition to this, it was also discovered that the turbulence model has a large effect on the particles in the near-wall region. Choosing an isotropic turbulence model resulted in clustering of the particles near the wall, therefore an anisotorpic turbulence model needed to be used.

京都大学 / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第18629号 / 地環博第124号 / 新制||地環||25(附属図書館) / 31529 / 京都大学大学院地球環境学舎環境マネジメント専攻 / (主査)教授 藤井 滋穂, 教授 高岡 昌輝, 准教授 田中 周平 / 学位規則第4条第1項該当 / Doctor of Global Environmental Studies / Kyoto University / DFAM