Volume 9: Oil and Gas Applications; Organic Rankine Cycle Power Systems; Steam Turbine最新文献

{"title":"Blade Damping Mechanisms and Some Recent Failures","authors":"Vamadevan Gowreesan, A. Guzman, W. Greaves","doi":"10.1115/GT2020-14007","DOIUrl":"https://doi.org/10.1115/GT2020-14007","url":null,"abstract":"\u0000 The rotating blades of a steam turbine perform the important task of converting the thermal energy of the steam into rotating mechanical work or torque. Hence, these blades have to be very robust and they need to be installed properly in the discs of the turbine. Damping mechanisms are used to improve the stiffness of the blades and to minimize the vibrations of the blades. Different types of blade damping mechanisms are used in steam turbines. Shroud bands, lashing or damping wires, pins, tie-bolts and lashing stubs/ snubbers are the most common types of damping mechanisms used in steam turbines. Several factors such as stress distribution, additional centrifugal stresses due to the added weight of the damping mechanisms, aerodynamic effects, resulting harmful mode shapes and critical vibration frequencies etc., need to be considered in the selection and the design of the damping mechanisms.\u0000 Due to the various types of operating conditions and stresses, the damping mechanisms can experience failure in service. Metallurgical evaluations of some of the recent failures of damping mechanisms are discussed here. Failures of shroud bands, blade tenons, tie-bolts and damping wires are the particular examples presented. SCC (stress corrosion cracking), fatigue and overload were found to be the main modes of failures in these examples. The purpose of discussing these examples is to make the designers, the manufacturers and the users aware of these potential issues so that corrective actions can be taken.","PeriodicalId":171265,"journal":{"name":"Volume 9: Oil and Gas Applications; Organic Rankine Cycle Power Systems; Steam Turbine","volume":"542 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122185491","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Hydrogen in Pipelines: Impact of Hydrogen Transport in Natural Gas Pipelines","authors":"R. Kurz, Matt Lubomirsky, Francis Bainier","doi":"10.1115/GT2020-14040","DOIUrl":"https://doi.org/10.1115/GT2020-14040","url":null,"abstract":"\u0000 The increased use of renewable energy has made the need to store electricity a central requirement. One of the concepts to address this need is to produce hydrogen from surplus electricity, and to use the existing natural gas pipeline system to transport the hydrogen. Generally, the hydrogen content in the pipeline flow would be below 20%, thus avoiding the problems of transporting and burning pure hydrogen. The natural gas – hydrogen mixtures have to be considered both from a gas transport and a gas storage perspective.\u0000 In this study, the impact of various levels of hydrogen in a pipeline system are simulated. The pipeline hydraulic simulation will provide the necessary operating conditions for the gas compressors, and the gas turbines that drive these compressors. The result of the study addresses the impact on transportation efficiency in terms of energy consumption and the emission of green house gases. Further, necessary concepts in the capability to store gas to better balance supply and demand are discussed.","PeriodicalId":171265,"journal":{"name":"Volume 9: Oil and Gas Applications; Organic Rankine Cycle Power Systems; Steam Turbine","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"123370306","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental and Numerical Study on Pressure Losses and Flow Fluctuations in a High-Pressure Valve Assembly of Steam Turbine Governing System","authors":"Václav Sláma, Lukáš Mrózek, Bartoloměj Rudas, D. Šimurda, J. Hála, M. Luxa","doi":"10.1115/GT2020-14474","DOIUrl":"https://doi.org/10.1115/GT2020-14474","url":null,"abstract":"\u0000 Aerodynamic measurements and numerical simulations carried out on a model of a high-pressure valve assembly used for nozzle governing of a turbine with 135MW output are described in this paper. Aim of the study is to investigate effects of control valve’s strainers on pressure losses and unsteadiness in the flow field. It is an important task since undesirable flow fluctuations can lead to operational reliability issues. Measurements were carried out in the Aerodynamic laboratory of the Institute of Thermomechanics of the Czech Academy of Sciences (IT) where an aerodynamic tunnel is installed. Numerical simulations were carried out in the Doosan Skoda Power (DSP) Company using ANSYS software tools. The experimental model consists of one of two identical parts of the real valve assembly. It means it consists of an inlet pipeline, a stop valve, a valve chamber with two independent control valves, its diffusers and outlet pipelines. The numerical model consists of both assembly parts and includes also an A-wheel control stage in order to simulate the real turbine operating points. The different lifts of the main cone in each control valve for its useful combinations were investigated. Results were evaluated on the model with control valve’s strainers, which were historically used in order to stabilize the flow, and without them. The results of the experimental measurement were compared with the numerical results in the form of pressure losses prediction. From measured pressure fluctuations, it was found out where and for which conditions a danger of flow instabilities occurs. It can be concluded that there is a border, in terms of operating conditions, where the flow field starts to be unstable and this border is different dependent of the fact whether the control valve’s strainers are used or not. Therefore, the areas of safe and danger operational reliability can be predicted. The influence of the control valve’s strainers on the maximal amplitude of periodic fluctuations appears only for the cases when valves are highly overloaded. For normal operating conditions, there is no difference. As a result, the control valve’s strainers do not have to be used in standard applications of valve assemblies. Furthermore, a loss model for valve pressure loss estimation could be updated. Therefore, a pressure loss should be predicted with a sufficient accuracy for each new turbine bid with similar valve assemblies.","PeriodicalId":171265,"journal":{"name":"Volume 9: Oil and Gas Applications; Organic Rankine Cycle Power Systems; Steam Turbine","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2020-09-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126577722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}