No description available.

This thesis was done at Siemens Industrial Turbomachinery AB in Finspång. Placed in the inlet to a steam turbine is a filter, a steam strainer, which separates particles and larger objects from the steam. These particles and objects will cause solid particle erosion in the actual turbine if they pass by. The strainer is exposed to large pressure drops when clogged, i.e., static loads which require a good creep resistance in the material. The temperature of the steam in the turbines is increased in order to deliver more energy; today’s turbines are dimensioned for almost 600°C. The material in parameters, such as the strainer, should also be adjusted to the higher temperatures. Today’s temperature is suspected to be the cause of damage in the strainer because the present material might get brittle at higher temperatures. The purpose of the thesis is to find a new material for the strainers and also to find a new concept for how to manufacture them. There are nine sizes of steam strainers but only five of them are exposed to the highest temperatures and pressure drops, which make only these five interesting to examine in this thesis. The concepts were chosen according to the method of Ulf Liedholm (1999), Systematic Concept Development. The thesis did not end up with only one concept because not all possible methods were tested but the suggestions are all based on a strainer built out of membranes as before. The discussed methods to join the membranes are EB-welding, laser welding and brazing. An investigation to find if it was possible to improve the strength of the strainer by simple design changes and a calculation of what percentage of clogging the strainer would hold for was also done. The chosen material was a creep resistant, alloy special steel. Three suggestions on concepts were presented. The improvements in strength from simple changes in design were too small and too costly but are enclosed as an appendix in this report. Calculations on the strength were done without regard taken to fatigue caused by possible vibrations, so-called high cycle fatigue. What would be interesting to do as a future work based on this thesis is, of course, to test the three manufacturing methods and evaluate them thoroughly but also to discuss other ways of improving the strength through design changes. These should be done regarding the flow. Also high cycle fatigue should be considered. / Examensarbetet utfördes i Finspång på Siemens Industrial Turbomachinery AB. I inloppet till en ångturbin sitter ett filter, en ångsil, som silar bort partiklar och större föremål från ångan. Dessa partiklar och föremål skadar turbinen genom erosion om de tillåts passera. Ångsilen i sig utsätts för stora tryckfall när den blir igensatt, vilket kräver god krypresistans i materialet. För att kunna leverera allt mer energi utvecklas ångturbiner som kan arbeta vid allt högre ångtemperaturer. De som konstrueras idag dimensioneras för närmare 600 °C. Då måste även materialet i detaljer, som silen, anpassas. De temperaturer som används idag misstänks vara en orsak till skador på silarna eftersom nuvarande material kan bli sprött då temperaturen stiger. Syftet med arbetet är att välja ett nytt material till ångsilarna samt att finna nya koncept för hur ångsilen kan tillverkas. Nio storlekar på ångsilar finns men bara fem av dessa används vid högsta temperatur och tryck och därför har enbart dessa fem använts vid beräkningar i detta examensarbete. Koncept valdes enligt Liedholms (1999) metod, Systematisk Konceptutveckling. Istället för ett slutligt koncept lämnas istället tre förslag. Detta görs då de olika förslagen inte har testats ordentligt. Samtliga tre förslag är baserade på den typen av sil uppbyggd av membran som används idag men med nya metoder att sammanfoga membranen med. Metoderna är EB-svetsning, lasersvetsning och vakuumlödning. En undersökning om det var ekonomiskt rimligt att förbättra hållfastheten genom enkla designändringar samt en beräkning över hur stor igensättning silen klarar gjordes. Materialet som valdes var ett krypresistant, legerat specialstål. De tre förslagen på koncept lades fram. Designändringarna gav inte det resultat som det hade hoppats på och var framförallt för dyra att genomföra. Hållfasthetsberäkningar gjordes utan hänsyn till utmattning på grund av eventuella vibrationer, så kallad högcykelutmattning. Som framtida arbete med detta examensarbete som språngbräda rekommenderas i första hand att testa de föreslagna metoderna för sammanfogning av membranen men även djupare diskussioner kring hur hållfastheten skulle kunna förbättras genom designförändringar borde tas. Dessa skulle kunna genomföras med avseende på flödet. Även högcykelutmattning, HCF, borde undersökas.

Combined Cycle power plants have recently become a serious alternative for standard coal- and oil-fired power plants because of their high thermal efficiency, environmentally friendly operation, and short time to construct. The combined cycle plant is an integration of the gas turbine and the steam turbine, combining many of the advantages of both thermodynamic cycles using a single fuel. By recovering the heat energy in the gas turbine exhaust and using it to generate steam, the combined cycle leverages the conversion of the fuel energy at a very high efficiency. The heat recovery steam generator forms the backbone of combined cycle plants, providing the link between the gas turbine and the steam turbine. The design of HRSG has historically largely been completed using thermodynamic principles related to the steam path, without much regard to the gas-side of the system. An effort has been made using resources at both UK and Vogt Power International to use computational fluid dynamics (CFD) analysis of the gas-side flow path of the HRSG as an integral tool in the design process. This thesis focuses on how CFD analysis can be used to assess the impact of the gas-side flow on the HRSG performance and identify design modifications to improve the performance. An effort is also made to explore the software capabilities to make the simulation an efficient and accurate.

Direct contact condensation of steam injected into water is a special mode of condensation where condensation occurs on the interface between steam and water. This type of condensation forms an essential part of various industrial applications and correct prediction and modelling of the condensation behaviour is crucial to obtain an optimised design of such devices. While present prediction models for direct contact condensation are valid for a limited range of flow conditions only, the work presented in this thesis provides improved models for direct contact condensation. The models are developed in the form of diagrams and include: a condensation regime diagram, for predicting the condensation behaviour, a steam plume length diagram, for predicting the penetration distance of steam into water, and a heat transfer coefficient diagram. These models are derived using a wide range of data and therefore provide more accurate predictions compared with alternative models available in literature. In contrast to present models, the derived models presented in this work are constructed using an additional physical parameter to describe the process. The diagrams are validated against independent experiments and demonstrate close agreement. Furthermore, the predictions from the condensation regime diagram and steam plume length diagram are self-consistent. The models developed in this study are capable of predicting condensation behaviour for a wide range of initial conditions and can be used in conjunction with computational fluid dynamics techniques for direct contact condensation.

Thesis (Ph. D.)--University of North Texas, May, 2007. / Title from title page display. Includes bibliographical references.

Thesis (M.S.)--University of North Texas, May, 2008. / Title from title page display. Includes bibliographical references.

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Made available in DSpace on 2014-10-09T12:25:58Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T14:00:24Z (GMT). No. of bitstreams: 1 00988.pdf: 3339929 bytes, checksum: 27ead5c2fe041a5b93b6fa5c9a4df73f (MD5) / Dissertacao (Mestrado) / IEA/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

No description available.

The main goal of my thesis is to carry out thermic calculations for adjusted conditions of electric and heat energy consumption. The power of the generator is 330 MW. In the proposal, you can find combustion trubines type GE 9171E. Steam-gas power plant is designed to combust metallurgical gases. Effort of the thesis focuses also on giving a new informations about trends in combinated production of electric and heat energy.