The goal of this thesis was to create a mathematical model of a steam turbine based on the data acquired by measurement, and to verify its behaviour. The first part contains research, which is supposed to introduce basic principles of the steam turbine and description of important construction parts and the possibilities of control. The second part describes the experimental identification method of least squares, used for the calculation of an ARX model of the steam turbine. Finally, the last part focuses on the program environment used for creation of the mathematical model and explanation of measured data analysis process. Furthermore this segment describes the created simulation program as well as a visualisation of the dynamic processes in the steam turbine, including the design of control.

Thesis (MScEng (Mechanical and Mechatronic Engineering))--University of Stellenbosch, 2006. / A small scale steam jet ejector experimental setup was designed and manufactured. This ejector setup is of an open loop configuration and the boiler can operate in the temperature range of Tb = 85 °C to 140 °C. The typical evaporator liquid temperatures range from Te = 5 °C t o 10 °C while the typical water cooled condenser presure ranges from Pc = 1 . 70 kPa t o 5. 63 kPa (Tc = 15 °C to 35 °C). The boiler is powered by by two 4kW electric elements, while a 3kW electric element simulates the cooling load in the evaporator. The electric elements are controlled by means of variacs. The function ... / Centre for Renewable and Sustainable Energy Studies

Thesis (PhD)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The steam-side side operation of a practical air-cooled steam condenser is investigated using a combination of CFD, numerical, analytical and experimental methods. Particular attention is directed towards the vapor flow distribution in the primary condensers and dephlegmator performance. Analysis of the vapor flow in the distributing manifold, connecting the steam turbine exhaust to the air-cooled heat exchangers, highlights the importance of careful design of the guide vanes in the manifold bends and junctions. Improved guide vane design and configuration can reduce the steam-side pressure drop over the manifold and improve the vapor flow distribution, which may be beneficial to condenser operation. The vapor flow in the primary condensers is shown to exhibit a non-uniform distribution amongst the heat exchanger tubes. The vapor flow distribution is strongly linked to the distribution of tube inlet loss coefficients through the heat exchanger bundles. The non-uniform flow distribution places an additional demand on dephlegmator performance, over and above the demands of row effects in the case of multi-row primary condenser bundles. Row effects are shown to account for as much as 70 % of available dephlegmator capacity in this case. Simultaneously, inlet loss coefficient distributions can account for up to 30 % of dephlegmator capacity. In some situations then, the dephlegmator is fully utilized under ideal operating conditions and there is no margin of safety to cope with non-ideal operation of the primary condensers. The upstream regions of the primary condensers are therefore exposed to a high risk of undesirable noncondensable gas accumulation. Reduced dephlegmator capacity due to insufficient ejector performance may further compound this problem. Single-row primary condenser bundles eliminate row effects and thereby significantly reduce the demands on dephlegmator performance. The use of such bundles in the dephlegmator would also measurably reduce ejector loading. In light of the findings of this study, it is recommended that single-row bundles be considered as the primary option for future air-cooled condenser applications. A hybrid (dry/wet) dephlegmator concept is analysed and shown to be able to provide measurably enhanced dephlegmator performance when operating in wet mode, while consuming only a small amount of water. The enhanced dephlegmator cooling translates to an increase in total air-cooled condenser capacity of up to 30 % at high ambient temperatures in this case. The benefit of this enhanced cooling capacity to steam turbine output may be significant. The hybrid dephlegmator concept therefore offers a simple, cost-effective and sustainable solution to the issue of reduced air-cooled condenser performance during hot periods. Careful design of the first and second stage bundle configurations in the hybrid dephlegmator is necessary to avoid flooding in the first stage during wet operation of the second. Furthermore, the slightly poorer dry-operation performance of the hybrid dephlegmator results in increased risk of non-condensable gas accumulation in multi-row primary condensers. Again, single-row primary condenser bundles would lay rest to such concerns. / AFRIKAANSE OPSOMMING: Die bedryf aan die stoom-kant van ʼn praktiese lugverkoelde-stoomkondensor word ondersoek met behulp van 'n kombinasie van berekeningsvloeimeganika, numeriese, analitiese en eksperimentele metodes. ʼn Spesifieke fokus word geplaas op die dampvloeiverspreiding in die primêre kondensors asook die deflegmatorwerksverrigting. Ontleding van die damp vloei in die verdeelspruitstuk, wat die uitlaat van die stoomturbine aan die lugverkoelde-stoomkondensor koppel, beklemtoon die belangrikheid van noukeurige ontwerp van die leilemme in die spruitstukdraaie en aansluitings. Verbeterde leilemontwerp en opstelling kan die drukval aan die stoom-kant van die draaie en aansluitings verminder en die dampvloeiverspreiding verbeter. Dit kan gevolglik lei tot verbeterde werksverrigting van die kondensor. Die studie toon dat ʼn nie-eenvormige dampvloeiverspreiding in die warmteruilerbuise van die primêre kondensors bestaan. Die verspreiding van buisinlaat-verlieskoëffisiënte deur die bundels van die warmteruiler is sterk afhanklik van die voorgenome dampvloeiverspreiding. Die nie-eenvormige vloeiverspreiding veroorsaak 'n groter aanvraag na deflegmator-werksverrigting, bo-en-behalwe nog vereistes van ry-effekte in die geval waar multi-ry-bundels vir primêre kondensors gebruik word. Ry-effekte is verantwoordelik vir so veel as 70 % van die beskikbare deflegmator kapasiteit. Terselfdertyd kan die verspreiding van inlaat-verlieskoëffisiënte verantwoordelik wees vir tot 30 % van die deflegmator kapasiteit. In sommige gevalle is die deflegmator dus ten volle aangewend onder ideale bedryfstoestande, en bestaan daar geen band van veiligheid om nie-ideale werksverrigting van die primêre kondensor te hanteer nie. Sekere dele van die stroom-op primêre kondensors word dus blootgestel aan 'n hoë risiko vir die opbou van ongewenste nie-kondenseerbare gasse. Verder kan ‘n vermindering in deflegmator kapasiteit, weens onvoldoende werksverrigting van die vakuumpompe, dié probleem vererger. Enkel-ry-bundels vir primêre kondensors vermy ry-effekte en lei sodoende tot ʼn aansienlike vermindering in die aanvraag na deflegmator-werksverrigting. Die gebruik van sulke bundels in die deflegmator sou die vakuumpomplas ook meetbaar verminder. Uit die bevindinge van hierdie studie word dit aanbeveel dat enkel-ry bundels beskou word as die primêre opsie vir toekomstige lugverkoelde-kondensor aansoeke. ’n Konsep vir ’n hibriede-deflegmator (droog/nat) word ontleed. Die studie toon dat, deur hierdie konsep in die nat-modus te gebruik, ’n meetbare verbetering in deflegmator-werksverrigting gesien kan word, ten koste van net ʼn klein hoeveelheid waterverbruik. Die verbetering in verkoelingsvermoë van die deflegmator beteken ʼn toename van tot 30 % in die totale verkoelingsvermoë van die lugverkoelde-kondensor gedurende periodes wanneer hoë omgewingstemperature heersend is. Die voordeel van hierdie verbeterde verkoelingsvermoë op die werksuitset van die stoomturbine kan beduidend wees. Die konsep vir ’n hibriede-deflegmator bied dus 'n eenvoudige, koste-effektiewe en volhoubare oplossing vir warm atmosferiese periodes, wanneer die lugverkoelde-kondensor se verkoelingsvermoë afneem. Noukeurige ontwerp van die eerste en tweede fase bundelkonfigurasies in die hibriede-deflegmator is nodig om oorstroming in die eerste fase, tydens nat werking van die tweede fase, te verhoed. Verder veroorsaak die effens swakker werksverrigting, gedurende die bedryf van die hibriede-deflegmator in die droog-modus, ʼn verhoogde risiko vir die opbou van nie-kondenseerbare gasse in multi-ry primêre kondensors. Weereens sal enkel-ry-bundels in primêre kondensors hierdie probleem oplos.

The presence of deposits on the secondary side of pressurized water reactor (PWR) steam generator systems is one of the main contributors to the high maintenance costs of these generators. Formation and transport of corrosion products formed due to the presence of impurities, metals and metallic oxides in the secondary side of the steam generator units result in formation of deposits. This research deals with understanding the deposit formation and characterization of deposits by studying the samples collected from different units in secondary side system at Comanche Peak Steam Electric Station (CPSES). Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) have been used for studying the phases, morphologies and compositions of the iron oxides formed at Unit 1 and Unit 2 of secondary side of steamgenerator systems. Hematite and magnetite were found to be the dominant phases of iron oxides present in the units. Fe, Cr, O, Ni, Si, Cl and Cu were found in samples collected from both the units. A qualitative method was developed to differentiate iron oxides using laser induced breakdown spectroscopy (LIBS) based on temporal response of iron oxides to a high power laser beam. A quantitative FTIR technique was developed to identify and quantify iron oxides present in the different components of the secondary side of the steam generator of CPSES. Amines are used in water treatment to control corrosion and fouling in pressurized water reactors. CPSES presently uses an amine combination of dimethylamine (DMA), hydrazine and morpholine to control the water chemistry. Along with the abovementioned amines, this study also focuses on corrosion inhibition mechanismsof a new amine DBU (1, 8-diazabicyclo [5.4.0] undec-7-ene). Electrochemical impedance spectroscopy and polarization curves were used to study the interaction mechanism between DBU solution and inconel alloys 600 and 690 at steamgenerator operating temperatures and pressures. Of all the amines used in this study (DMA, DBU, ETA, and morpholine), DMA was more effective at keeping the passive film formed on the alloy 600 surface from failing at both ambient and high temperatures. Morpholine was found result in higher corrosion resistance compared to the other amines in case of alloy 690.

Ce travail a porté sur la conversion du méthane et de l'éthanol en hydrogène par le procédé du vaporeformage en utilisant de nouvelles formulations de catalyseurs afin d'augmenter la sélectivité en produit désiré (hydrogène), de réduire la production du monoxyde de carbone (Co) et défavoriser la formation de coke. Deux familles de phases actives, à base de cuivre et de ruthénium supportés par les hydrotalcites calcinées CoₓMg₆₋ₓAl₂, ont été évaluées dans ces réactions. Pour les deux réactions, l'influence de plusieurs facteurs a été évaluée afin d'ajuster les paramètres de la réaction. Il a été démontré que les performances des catalyseurs pour les réactions du vaporeformage dépendent de la teneur en cobalt et en magnésium.Une grande teneur en cobalt améliore la réactivité catalytique. Le catalyseur 1Ru/Co₆Al₂ a présenté la plus forte activité et stabilité dans la réaction du vaporeformage du méthane parmi les autres catalyseurs industriels et préparés. Les espèces réduites de ruthénium et du cobalt ont été détectées après la réaction par DRX. La technique RPE était capable de détecter des quantités négligeables de deux types d'espèces carbonées formées lors de la réaction : du coke et du carbone. D'autre part, le catalyseur 5Cu/Co₆Al₂ a révélé la productivité la plus élevée en hydrogène dans la réaction du vaporeformage de l'éthanol. Cependant, il se désactive après quelques heures à cause de la formation du coke. Le catalyseur 5Cu/Co₂Mg₄Al₂ a montré une quantité beaucoup plus faible d'espèces carbonées sans désactiver pendant 50 heures en raison du caractère basique de la phase de l'oxyde du magnésium présente dans le support. / This work focuses on methane and ethanol conversion to hydrogen in the presence of a catalyst in order to increase the selectivity of the desired product (H₂) and reduce carbon monoxide emission and coke formation. Two kinds of active phase were used (copper and ruthenium) and impregnated on calcined hydrotalcites CoₓMg₆₋ₓAl₂ in order to be evaluated in the methane and ethanol steam reforming reactions. For both reactions, the influence of several factors was evaluated in order to adjust the reaction parameters. It has been shown that catalysts performances for the reforming reactions depend on the content of cobalt and magnesium. High cobalt content enhanced the catalytic activity. 1Ru/Co₆Al₂ catalyst presented the highest activity and stability in the methane steam reforming reaction among the other industrial and prepared catalysts even under a low GHSV and with no hydrogen pretreatment. Reduced ruthenium and cobalt were detected after the reaction by XRD. EPR technique was able to detect negligible amount of two kinds of carbonaceous species formed during the reaction : coke and carbon. On the other hand, 5Cu/Co₆Al₂ catalyst revealed the highest hydrogen productivity in the ethanol steam reforming reaction. However, it suffers from coke formation that deactivated the catalysts after few hours. 5Cu/Co₂Mg₄Al₂ catalyst showed a much lower quantity of carbonaceous species with no deactivating during 50 hours due to the basic character of the magnesium oxide phase present in the support.

A 16×16×5.6 in. scaled, three-dimensional, physical model of a quarter of a 9-spot pattern was constructed to study the application of two processes designed to improve the efficiency of steam injection. The first process to be tested is the use of propane as a steam additive with the purpose of increasing recovery and accelerating oil production. The second process involves the use of a novel production configuration that makes use of a vertical injector and a smart horizontal producer in an attempt to mitigate the effects of steam override. The experimental model was scaled using the conditions in the San Ardo field in California and crude oil from the same field was used for the tests. Superheated steam at 190 – 200ºC was injected at 48 cm3/min (cold water equivalent) while maintaining the flowing pressures in the production wells at 50 psig. Liquid samples from each producer in the model were collected and treated to break emulsion and analyzed to determine water and oil volumes. Two different production configurations were tested: (1) a vertical well system with a vertical injector and three vertical producers and (2) a vertical injector-smart horizontal well system that consisted of a vertical injector and a smart horizontal producer divided into three sections. Runs were conducted using pure steam injection and steam-propane injection in the two well configurations. Experimental results indicated the following. First, for the vertical configuration, the addition of propane accelerated oil production by 53% and increased ultimate recovery by an additional 7% of the original oil in place when compared to pure steam injection. Second, the implementation of the smart horizontal system increased ultimate oil recovery when compared to the recovery obtained by employing the conventional vertical well system (49% versus 42% of the OOIP).

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: The use of air-cooled steam condensers (ACSCs) is the preferred cooling method in the chemical and power industry due to stringent environmental and water use regulations. The performance of ACSCs is however highly dependent on the influence of windy conditions. Research has shown that the presence of wind reduces the performance of ACSCs. It has been found that cross-winds (wind perpendicular to the longest side of the ACSC) cause distorted inlet flow conditions, particularly at the upstream peripheral fans near the symmetry plane of the ACSC. These fans are subjected to what is referred to as '2-D' wind conditions, which are characterised by flow separation on the upstream edge of the fan inlets. Experimental investigations into inlet flow distortion have simulated these conditions by varying the fan platform height. Low platform heights resulted in higher levels of inlet flow distortion, as also found to exist with high cross-wind speeds. This investigation determines the performance of various fan configurations (representative of configurations used in the South- African power industry) subjected to distorted inlet flow conditions through experimental and numerical investigations. The similarity between platform height and cross-wind effects is also investigated and a correlation between system volumetric effectiveness, platform height and cross-wind velocity is found. / AFRIKAANSE OPSOMMING: Die gebruik van lugverkoelde stoom kondensors (LVSK's) word verkies as 'n verkoelingsmetode in die chemiese- en kragvoorsieningsindustrie as gevolg van streng omgewings- en waterverbruiksregulasies. Die werkverrigting van LVSK's word egter grootliks beïnvloed deur die teenwoordigheid van wind. Navorsing het gewys dat die teenwoordigheid van wind die werkverrigting van LVSK's verminder. Daar was gevind dat kruiswinde (wind loodreg tot die langste sy van die LVSK) versteurde inlaat vloeitoestande veroorsaak, veral by waaiers wat aan die stroomop kant van die LVSK naby die simmetrievlak geleë is. Hierdie waaiers word blootgestel aan na wat verwys word as '2-D' windtoestande wat gekenmerk word deur vloeiwegbreking wat plaasvind by die stroomop rand van die waaierinlate. Eksperimentele ondersoeke van inlaat vloeiversteurings het hierdie toestande gesimuleer deur die waaier platformhoogte te verstel. Lae platform hoogtes het gelei tot hoër vlakke van inlaat vloeiversteuring, soortgelyk aan wat gevind word met hoë kruiswindsnelhede. Hierdie ondersoek gebruik numeriese en eksperimentele metodes om die werkverrigting van verskeie waaierkon gurasies (verteenwoordigend van kon- gurasies wat gebruik word in die Suid-Afrikaanse kragvoorsieningsindustrie) wat blootgestel word aan versteurde inlaat vloeitoestande te bepaal. Die ooreenkoms tussen platformhoogte en kruiswind e ekte word ook ondersoek en 'n korrelasie tussen die sisteem volumetriese e ektiwiteit, platformhoogte en kruiswindsnelheid word bepaal.

Det finns ett stort behov av att minska energianvändningen i världen. Igenom att minska energibehovet så minskar den negativa miljöpåverkan. I en ständigt växande värld där det byggs i allt snabbare takt så ökar också energibehovet. Igenom att effektivisera befintliga byggnader kan energibehovet stagnera eller till och med minska trots utbyggnaden. Igenom att energieffektivisera så kan mer av den energi som används nyttjas istället för att den ska stå för onödiga förluster. Fortifikationsverket har en restaurangbyggnad de anser använder för mycket energi. Denna byggnad innehåller en restaurang som använder ett ångsystem för matproduktion, vilket gör byggnadens energisystem unikt. För att kunna minska byggnadens energianvändning kartläggs och analyseras den i denna rapport. Denna fallstudie genomförs med en litteraturstudie för att utveckla kunskaperna inom området. Sedan utförs mätningar i byggnaden som därefter analyseras och presenteras så att eventuella avvikelser och brister påpekas. Under arbetets gång upptäcktes att en säkring var felinstallerad för mätningen av elanvändningen till en av ångpannorna. Igenom att ha åtgärdat detta för att kunna fakturera rätt så spar Fortifikationsverket nästan 170 000 kr per år som den ångpannan går. Utöver detta så analyserades ångsystemet och uppskattningar gjordes för att kunna svara på om ånga är effektivare än el för matlagning. Det visar sig att ångsystemet kan vara effektivt om stor mängd mat tillagas. Med hänsyn till nätter, helger och de dagar då mindre mat tillagas så är el-utrustning effektivare eftersom att det helt stängs av när det inte används. Till skillnad från ångsystemet som måste täcka upp för förlusterna för att behålla temperatur och tryck, även när systemet inte används. Igenom att byta ut ångsystemet till motsvarande utrustning som drivs av el skulle det gå att spara 205 MWh/år, enligt uppskattningar. Ångsystemet står för 35% av byggnadens totala elanvändning och är den största posten för energianvändningen och är därför den del som fokuserats mest på. Utöver ångsystemet så analyserades övrig energianvändning för att kunna ge förslag på besparingar. Många av förslagen är grundade på vissa uppskattningar och antaganden vilket måste beaktas. Några konkreta exempel på besparingar som kan göras är att sänka inomhustemperaturen för att spara 50 MWh/år, installera tilläggsfönster för att spara upp till 140 MWh/år, installera effektivare kylaggregat – 200 MWh/år, installera bättre styrning till ventilationen – 110 MWh/år, installera bättre styrning till belysning – 40 MWh/år. / There is a great need to reduce energy use in the world. By reducing energy demand, this reduces the negative environmental impact. In a constantly growing world, where it is built at an ever faster pace, the energy demand also increases. By increasing energy efficiency inexisting buildings, energy requirements may stagnate or even decrease despite expansion. By increasing energy efficiency, more of the energy demand can be used instead of standing for energy losses. Fortifikationsverket has a building they believe use too much energy. This building contains a restaurant that uses a steam system to heat its food, which makes the building's energy system unique. In order to reduce the energy consumption of the building, an energy audit is completed and analyzed in this report. This case study is conducted with a literature study to develop the knowledge in the field. Then measurements in the building are performed which are subsequently analyzed and presented to indicate any deviations and deficiencies. During the work it was discovered that a fuse was incorrectly installed to measure the electricity consumption of one of the boilers. By correcting this in order to be able to bill correctly, Fortifikationsverket saves almost 170,000 SEK per year as the boiler goes. In addition to this, the steam system was analyzed and estimates were made to respond if steam is more effective than electricity for cooking. It turns out that the steam system can be effective if a large amount of food is cooked. Considering nights, weekends and days when less food is cooked, electrical equipment is more effective because it completely turns off when not in use. Unlike the steam system that has to cover the energy losses to keep temperature and pressure, even when the system is not in use. By replacing the steam system with equivalent electrical equipment, it couldsave 205 MWh/year, according to estimates.The steam system accounts for 35% of the building's total electricity demandand is the largest item for energy use and is therefore the most focused area. In addition to the steam system, other energy usage was analyzed to provide energy savings. Many of the proposals are based on certain estimates and assumptions which must be considered. Some examples of savings that can be made is lowering the indoor temperature to save 50 MWh/year, install additional windows to save up to 140 MWh/year, install more efficient cooling units -200 MWh/year, install better ventilation control systems-50 MWh/year, install better controls for indoor lighting -40 MWh/year.

The presence of deposits leading to corrosion of the steam generator (SG) systems is a major contributor to operation and maintenance cost of pressurized water reactor (PWR) plants. Formation and transport of corrosion products formed due to the presence of impurities, metallic oxides and cations in the secondary side of the SG units result in formation of deposits. This research deals with the characterization of deposit samples collected from the two SG units (unit 1 and unit 2) at Comanche Peak Steam Electric Station (CPSES). X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) techniques have been used for studying the compositional and structural properties of iron oxides formed in the secondary side of unit 1 and unit 2. Magnetite (Fe3O4) was found to be predominant in samples from unit 1 and maghemite (g-Fe2O3) was found to be the dominant phase in case of unit 2. An attempt has been made to customize FTIR technique for analyzing different iron oxide phases present in the deposits of PWR-SG systems.

Flow accelerated corrosion (FAC) is a major concern in the power industry as it causes thinning of the pipes by the dissolution of the passive oxide layer formed on the pipe surface. Present research deals with comparing the protection offered by the magnetite (Fe3O4) versus maghemite (γ-Fe2O3) phases thickness loss measurements. Fourier transform infrared spectroscopy (FTIR) is used in distinguishing these two elusive phases of iron oxides. Representative pipes are collected from high pressure steam extraction line of the secondary cycle of unit 2 of Comanche Peak Steam Electric Station (CPSES). Environmental scanning electron microscopy (ESEM) is used for morphological analysis. FTIR and X-ray diffraction (XRD) are used for phase analysis. Morphological analysis showed the presence of porous oxide surfaces with octahedral crystals, scallops and "chimney" like vents. FTIR revealed the predominance of maghemite at the most of the pipe sections. Results of thickness measurements indicate severe thickness loss at the bend areas (extrados) of the pipes.