Master’s thesis deals with design and calculation of one body condensing steam turbine of 25 MW with samples for paper-making industry. The thesis is focused on calculation of the turbine’s heat balance with two technological samples and regeneration which consists of two low pressure heaters and a deaerator with a power reservoir. The steam turbine is designed with a water cooling condenser with down output. The flow part is calculated with lengths of blades. There are basic strength and proportion calculations. In the end of the thesis the turbine’s heat balance is recalculated to 80% and 105% scheme according to an assignment. Another part of this thesis is a drawing of a longitudinal cut of the turbine including a connector with a gearbox.

The theme of this thesis is design of single body condensing steam turbine of 50 MW to saturated steam for new nuclear power plant generation. In the thesis is made design and calculation of balancing scheme. On the basis of the calculation is made blades part of turbine. Furthermore, the thesis solves basic strength and structural calculations. The result is drawing of longitudinal cut of the turbine.

In this masters thesis are discusses the possibilities of increasing the electrical efficiency of cogeneration units with an internal combustion engine with the power output 800 kWe. Technical and economical aspect the connection with steam turbine, steam engine and ORC turbine is compared. It include the design of heat exchanger for ORC cycle.

The aim of this master’s thesis is a retrofit of condensing three case steam turbine K300-170 with reheating. In the first part, the heat balance of the system is calculated for given parameters. The design of the flow section is focused on the combined intermediate pressure and low pressure turbine section and it consists of defining rotor and blading characteristics. In the stress control, the stress of the designed blading is checked and for the conclusion the shaft seal losses and their effect on the overall output power of the turbine are estimated. The drawing of axial section of combined intermediate pressure and low pressure turbine section is also included in the thesis.

The master thesis deals with modal analysis of the blade of the steam turbine impeller. This analysis is made to find the frequency response of the blade in order to predict the dangerous speeds of the steam turbine. At first the problem situation is described. Than follows the research study which is focused on steam turbines and especially on the rotor dynamic systems and the way to ascertain the modal parameters of the dynamic system by experiment. After that the solution of the problem is performed by computational modelling. The results of the computation are analyzed in detail for different variations of the blade length by Campbell diagram. A graph showing dependency between dangerous speeds of the turbine and the blade length is made out of the results. Then the results are verified by experiment and the coefficients of proportional damping are specified. In conclusion the optimal variation of the blade length for the given operational state is determined.

This diploma thesis describes a design of condensing steam turbine out of entered data of vapor parameters. There is selected a reaction blading type according to a conception of the company PBS Energo PLC. The turbine has one controlled extraction and three uncontrolled ones. The work also includes a proposal of thermal scheme, bearing and gearbox assignment. Furthermore there is also made a draft design of longitudinal section turbine

The aim of this master thesis is the retrofit of a condensing steam turbine. The thesis obtains a revision of the steam turbine, the reconstruction of steam turbine blades and the basic calculation of bolt torques of the turbine split plane. The master thesis is assigned to a specific retrofit of the steam turbine Lang. In the introductory part the thesis is focused on the turbine description and the basic functions of selected turbine components. The following part deals with the revision and the proposal of repairs for all components and the recommendation of additional modernizations of specific measuring equipments. The analysis of anchoring the stator and rotor blading and their reconstruction is discussed in the next part. In the last part the thesis focuses on the sealing of the turbine split plane and the calculation of the various bolt torques closely linked to the sealing.

This master thesis has examined how two of the heat pumps at Norrenergi, Solnaverket, can be converted to steam driven heat pumps. The heat pumps are driven by electrical motors today and this thesis has investigated the technical and economical aspects of replacing them with steam turbines and also installing a pellet boiler. The purpose with this project is to lower the costs for the heat pumps which varies with the electricity price, where the electricity taxes represent about 40-60 % of the total electricity cost. In addition, Norrenergi is one of the largest electricity consumers in Stockholm. This, combined with the prevailing capacity shortage in Stockholm makes it important to examine another alternative than electricity for the heat pumps. Capacity shortage means that electricity can't be transmitted into the city during periods with high electricity demand. The results of this master thesis show that the costs reduces on a system level when two steam driven heat pumps are installed compared to the electrity driven heat pumps. All district heating plants in Stockholm, including Söderenergi's, Norrenergi's and Stockholm Exergi's plants, have been involved while examining the costs in this study. Despite the cost reduction the investment calculation shows that the investment is not profitable for a low or average electrity price. For a high electricity price the investment seems to be profitable, but this is not considered enough for the investment to be recommend since future electricty prices are hard to predict. On the other hand there might be other aspects than economical to invest in this type of district heating plant, for example from a sustainability perspective. / Norrenergi är ett fjärrvärme- och fjärrkylabolag i Stockholm som bland annat producerar värme via energiåtervinning i en VP-anläggning i Solnaverket. Värmepumparna har en total värmeeffekt på 100 MW och drivs av elektricitet samt spillvatten från Bromma reningsverk. Kostnaden för att producera fjärrvärme via värmepumpar varierar med elpriset där en betydande faktor är elskatten. Elskatten utgör ungefär 40–60 % av den totala elkostnaden för VP-anläggningen i Solnaverket. Utöver de höga kostnaderna för att driva VP-anläggningen råder en så kallad kapacitetsbrist i Stockholm vilket bland annat grundar sig i att staden växt i en snabbare takt än utbyggnaden av stamnätet. På grund av ovan nämnda orsaker är det intressant att undersöka alternativa lösningar för hur den eldrivna VP-anläggningen kan producera fjärrvärme, dels för att minska kostnader för elektricitet men också för att bidra till en samhällsnytta genom att minska effektuttaget på elnätet. Detta examensarbete ämnar därför undersöka hur två av värmepumparna i Solnaverket kan omvandlas från eldrift till mekanisk ångdrift via ångturbiner, där ångturbinerna i sin tur drivs av ånga från en pelletspanna. Därtill undersöks systemdriftsnyttan, där även Stockholm Exergis och Söderenergis anläggningar beaktas, samt lönsamheten för att konvertera två av värmepumparna till ångdrift. Resultatet visar att systemdriftsnyttan är positiv oavsett elprisprofil vilket beror på att kostnaderna på systemnivå minskar när ångdriven VP-anläggning implementeras i Solnaverket. Trots den positiva systemdriftsnyttan visar dock investeringskalkylen att denna investering endast är lönsam vid ett högt elpris. Det beror bland annat på att den positiva systemdriftsnyttan inte är tillräckligt hög (vid låg och medelelpris) för att uppnå ett tillräckligt högt nuvärde med given kalkylränta och ekonomisk livslängd, i jämförelse med grundinvesteringskostnaderna. Den låga lönsamheten beror dessutom på att Stockholm Exergi ska bygga ett nytt avfallskraftvärmeverk i Lövsta som har billigare produktionskostnader än den ångdrivna VP-anläggningen. Det är svårt att förutspå elprisets utveckling framöver och variationerna i elpris under året förväntas öka, därför är det rekommenderat att denna investeringen inte genomförs eftersom den beror så pass mycket av elpriset. Det kan dock finnas andra aspekter än ekonomiska i att investera i en ångdriven VP-anläggning. Till exempel ur ett hållbarhetsperspektiv då belastningen på elnätet minskar när de eldrivna VP:arna konverteras till ångdrift.

Turbines encounter blade failures due to fatigue and creep. It has been shown in the literature that the primary cause of steam turbine blade failures worldwide can be ascribed to fatigue in low pressure (LP) turbine blades. The failure and damage to these blades can lead to catastrophic consequences. Some utilities use empirical methods to determine the forces experienced by turbine blades but desire more accurate methods. The inaccurate prediction of high-cycle fatigue (HCF), thermal durability and stage performance is introduced when one does not consider blade row interaction. Blade row interactions can, however, be accounted for by means of computational fluid dynamics (CFD). Furthermore, modern high- fidelity CFD tools would be able to contribute greatly in predicting the forces experienced by turbine blades. Numerical tools such as CFD and nite element analysis (FEA) can greatly contribute to the estimation of the remaining useful life (RUL) of turbine blades. However, in this estimation process, there are various uncertainties and aspects that affect the estimated RUL. Understanding the sensitivity of the estimated RUL to these various uncertainties and aspects is of great importance if RUL is to be estimated as accurately as possible. In this dissertation, a sensitivity analysis is performed with the purpose of establishing the sensitivity of the estimated RUL of the last stage rotor of an LP steam turbine, to the number of harmonics used in a nonlinear harmonic (NLH) CFD simulation. The sensitivity of the estimated RUL is evaluated in the HCF regime, where the cyclic stresses occur below the yield strength of the turbine blade. A CFD model, FE model, and fatigue model were therefore developed in such a manner that would suffice, regarding the purpose of the sensitivity analysis. The CFD model is validated by comparing the predicted CFD power to that of actual generated power of a dual 100MW LP steam turbine. The sensitivity analysis is performed for 3 operation conditions, and for each operational condition the aerodynamic forces were computed using 1, 2, and 3 harmonics in an NLH simulation. The estimation process considers a weak coupling between the CFD model and FE model. NLH simulations are firstly performed to calculate the unsteady static surface pressure distributions on the last stage rotor. This is followed by the mapping thereof to the FE model, for which a transient structural analysis is performed. Finally, the RUL is estimated by performing a fatigue analysis on the stress history obtained from the transient structural analysis. Based on the results of the sensitivity analysis, the following recommendations were made, from a conservative point of view. Firstly, in general, if the RUL is to be estimated with reasonable accuracy, just using 1 harmonic in an NLH simulation will not be sufficient and 2 harmonics should be used. Secondly, if the RUL has to be estimated with high accuracy, 3 harmonics should be used. / Dissertation (MEng)--University of Pretoria, 2018. / National Research Foundation (NRF) / Mechanical and Aeronautical Engineering / MEng / Unrestricted

Abstract In Sri Lanka, around 50% of the electrical energy generation is done using thermal energy, and hence maintaining generation efficiencies of thermal power plants at an acceptable level is very important from a socio-economic perspective for the economic development of the country. Efficiency monitoring also plays a vital role as it lays the foundation for maintaining and improving of generation efficiency. Heat rate, which is the reciprocal of the efficiency, is used to measure the performance of thermal power plants. In combined cycle power plants, heat rate depends on ambient conditions and efficiencies of subsystems such as the gas turbine, Heat Recovery Steam Generator (HRSG), steam turbine, condenser, cooling tower etc. The heat rate provides only a macroscopic picture of the power plant, and hence it is required to analyse the efficiency of each subsystem in order to get a microscopic picture. Computer modelling is an efficient method which can be used to analyse the each subsystem of a combined cycle power plant. Objective of this research is to develop a computer based tool which simulates the performance of subsystems of a combined cycle power plant in Sri Lanka. At the inception of the research, only heat rate was measured, and performances of subsystem were unknown.                  During the analysis, plant is divided into main systems, in order to study them macroscopically. Then, these main systems are divided into subsystems in order to have a microscopic view. Engineering equation solver (EES) was used to develop the tool, and the final computer model was linked with Microsoft excel package for data handling. Final computer model is executed using both present and past operating data in order to compare present and past performance of the power plant.             In combined cycle power plants steam is injected into the gas turbine to reduce the NOx generation and this steam flow is known as NOx flow. According to the result it was evident that turbine efficiency drops by 0.1% and power output increase by 1MW when NOx flow increases from 4.8 to 6.2kg/s. Further it was possible to conclude that gas turbine efficiency drop by 0.1% when ambient temperature increased by 3 C; and gas turbine power output decrease by 2MW when ambient temperature increases from 27 to 31 degrees.   Regarding the steam cycle efficiency it was found that steam turbine power output drops by  0.5MW when ambient temperature increases from 27 to 31 degrees; and steam cycle efficiency increases by 1% when NOx flow increases from 4.8 to 6.2kg/s. Further, steam turbine power output decreases by 0.25MW When NOx flow increases from 4.8 to 6.2kg/s                 Heat rate, which is the most important performance index of the power plant, increases by 10units (kJ/kWh) when ambient temperature increases by 3 C. Heat rate also increases with raising NOx flow which was 6.2kg/s in 2007 and 4.2kg/s in 2011. Hence, heat rate of the power plant has improved (decreased) by 10units (kJ/kWh) from 2007 to 2011.                Other than above, following conclusions were also revealed during the study.                         1)       HRSG efficiency has not change during past 4 years 2)     Significant waste heat recovery potential exists in the gas turbine ventilation system in the form of thermal energy