Failure based repairs can be devastating in nature to the plants overall viability. Failure analysis of rotating blades of lowpressure steam turbine. The paper presents results of research and failure analysis undertaken to determine failure causes of a steam turbine casing. Despite of numerous research and development in the. These units have one highpressure turbine and two tandemcompound lowpressure turbines with 44in. Root cause analysis of steam turbine blade failure springerlink. Dec 14, 2016 steam turbine journal bearing and its function steam turbines have journal bearings and thrust bearings. During the maintenance of a steam turbine, several l2. In case of turbines with cooling water preheating and lowpressure lp bypass, prior to supplying steam the regeneration and dumping systems have to be. Steam turbine blade failures, causes and correction.
Failure mode and effect aanalysis on power plant boiler. The consequences of a rotor failure are severe in terms of both safety and economic impact. Thompson, schweitzer engineering laboratories, inc. Determination of failure causes of a steam turbine casing. Rotor bending that results in premature failure of steam turbine blades and other internal components is. Overspeed events not only cause very large or total destruction of the steam turbine generator. Not only has construction and control become more complex but materials have been pushed closer to their operating limits. Excellent steam purity is essential for a turbine operation it is essential to monitor the steam purity of the steam going to a high pressure turbine. Maintenance and overhaul of steam turbines wgp42 05.
Steam path damage, particularly of rotating and stationary blading, has long been recognized as a leading cause of steam turbine unavailability for large fossil fuel plants worldwide. Failures of turbine rotor blades have been identified as the leading causes of unplanned outages for steam turbine. In water tube boilers thermal fatigue can occur when there is frequent wetting of a hot surface such as is caused by an ill placed and leaking valve dripping internally into a hot steam line. Prior to supplying steam to the turbine, the steam supply pipelines have to be drained and heated up. Steam turbine rotors are among the most critical and highly stressed components in modern power plants. Reliability investigation of steam turbine used in thermal. Noles references module 23414 turbine operational problems. A last stage turbine blades failure was experienced in two units of 660 mw. Failure to perform timely inspections and maintenance can lead to. Analysis of steam turbine blade failure causes request pdf. Investigation of steam turbine blade failure oaktrust. The following paper presents the results of the analysis of failure causes of the rotor shaft of a steam turbine with the power of 6,43 mw, which occurred after approximately one year of operation. Mw unit of a fossil fuel power plant operated in western part of india, low pressure turbine 3a stage blades failed prematurely. This article will outline the necessary steps to take while managing major steam turbine repairs.
Vibration in steam turbines engineering photos,videos and. Exponent was hired to assist in a root cause failure analysis. This is called an overspeed event and is the worst failure scenario for a steam turbine. Evolution of cracking in lp blade from corrosion, scc, lcf, and hcf. Abstractsynchronizing a generator to the power system must be done carefully to prevent damage to the machine and disturbances to the power system. An appendix explains methods used to compare stress levels against allowable values. Steam turbine overspeed protection failures, causes, and strategies to avoid them. Steam turbine moving blade failure caused by corrosion fatigue. The rate of the deterioration is influenced by the turbine design, the steam quality, and the way the turbine is operated. Steam turbine valve risk exposure steam turbine valves must be considered safety critical background.
Failure investigation was carried out using various techniques such as visual examination, stereo microscopy. In general, a steam turbine is a rotary heat engine that converts thermal energy contained in the steam to mechanical energy or to electrical energy. Blade failure was observed on a backpressure steam turbine driving a centrifugal compressor after it was in service for more than one year. Many power plant personnel are aware that chemistry upsets in a steam generator may cause severe corrosion and failure of boiler waterwall tubes and other components. Leakage solid particle erosion moisture erosion steam path deposits. Pages 48 c two general operating practices used to prevent its excessive pages 910 levels. Rotor bending that results in premature failure of steam turbine blades and other internal components is one of the most serious. For this reason, the steam turbines are specially protected to detect high levels of vibration and cause stop it before serious damage even happen. Pdf failure analysis of the 350 mw steam turbine blade root. Analysis of reasons of steam turbogenerator failure. This investigation deals with the recent various failures especially in the low pressure steam turbine blades which show varying load conditions. An industrial steam turbine experiences performance deterioration over time.
Corrosion fatigue has been identified as one of the leading causes of steam turbine rotor blades failure. A turbine component characteristics and failure mechanisms 2. After,000 hours of service the crack in a outer shell of the. Request pdf analysis of steam turbine blade failure causes the steam turbine blade is generally failed due to crack which is effect of fatigue, corrosion, pitting and creep. One thrust bearing typically is provided for the entire steam turbine to maintain the axial position of the rotor. The main objective of the paper is to present an analysis that leads to detect the most possible cause of the l0 blade fracture. The fracture appeared 5 inches from the blade root platform, fig. Vibration was initially mitigated by derating the units power output, but the plant owner desired full identification of the root cause of the vibration and issue resolution. Attention is devoted in the paper to state analysis of steam turbine after failure and possible causes of its damage. The following paper presents the results of the analysis of failure causes of the rotor shaft of a steam turbine with the power of 6,43 mw, which occurred after approximately one year. Steam turbine antimotoring reverse power rotor damage risk. A total destruction of the steam turbine can occur if a valve fails to close when the unit is tripped and driven equipment is no longer loaded. Flexible operations impact on steam turbine failure modes and. Flexible operations impact on steam turbine failure modes and best practices thomas r.
In the event of turbine blade failure, turbine does not work and this leads to shutdown of power plant from one to four weeks or longer, depending on the extent of the damage and the procedure used to make the machine operational again, which results in economic loss and. However, the inspection and maintenance of these valves is critical. The investigation shows that steam turbine 2 has maximum failure rate and minimum reliability in comparison to turbine 1. Routine preventive maintenance should be given additional attention to improve the performance of power plant. Three major steam turbine repair types have become clear as a result of this shift in maintenance focus. Fatigue, corrosion fatigue cf, and stress corrosion cracking scc of major steam turbine components, such as blades, discs, and rotors, have been consistently identified among the main causes of turbine unavailability. As a senior engi neer, he was engaged in commissioning of large turbines and troubleshooting in steam power plants. Steam turbine blade failure analysis sciencedirect. So, all these mountings have their individual center of mass now when this center of mass does not lie on the central axis of the shaft, they create an imbalance of centrifugal forces while rotating. Failure analysis of a steam turbine rotor sciencedirect. The rotors of steam turbines belong to the extremely loaded parts of turbo generators due to various mechanical and thermal influences during their operation. Protecting your steam turbine from corrosion power. This paper reports and analyses some tribological troubles experienced in actual steam turbine power plants in japan. Low cycle fatigue life estimation of steam turbine casing.
Steam turbogenerators are often used for production of electric energy in companies where sources of steam with necessary technical parameters are produced in technological process. Journal bearings are at each end of each rotor to support the weight of the rotor. Second piece was used for microstructural examination after manual grinding and polishing. The following paper presents the results of the analysis of failure causes of the rotor shaft of a steam turbine with the power of 6,43 mw, which. The blades are made of x20cr tempered martensitic stainless steel material. Failure analysis of rotating blades of low pressure steam turbine rotors and possibility of prediction corrosionfatigue ruptures. Steam turbine antimotoring reverse power rotor damage risk motoring can happen when a turbines steam supply is lost whilst the generator is still coupled to a network or operated in parallel with another generator. A various researchers have done the failure investigation of steam turbine blades. Main root causes for performance deterioration are.
Lifetime extension of steam turbine after blade failure a 28 mw steam turbine owned by a mining company in south sulawesi was experiencing excessive vibration. May 02, 2019 in the power plant steam turbine is a prime mover and on this prime mover blades and vanes are mounted which help in expansion of steam. Causes and solutions steam turbine rotors bend during operation, but the bearing and supports are designed to keep the static and dynamic forces under control. The field inspection revealed that one of last stage blades and the damping wire were broken. This paper presents details of observations, inspections carried out and root cause analysis of the turbine blade failure. Pdf this paper presents an analysis of the cause of fracture in a steam turbine blade root.
Also included are chapters on failure analysis, evaluation of circumstantial evidence, failure history, and investigative procedures. The steam turbine blade is generally failed due to crack which is effect of fatigue, corrosion, pitting and creep. Such failure of a steam line could have very serious consequences. Failures of blades, discs, and rotors in both fossil. The blades that failed were in a low pressure lp turbine connected to the high pressure turbine lp1 and in lp turbine connected to the generator. The company awarded sulzer a contract to perform the complete inspection and repair. Steam turbine overspeed protection failures, causes, and. Steam turbine blading can be subjected to several failure me chanisms in service. Steam turbine blade failures, causes and correction oaktrust. Proceedings of the 2012 20th international conference on nuclear engineering and the asme 2012 power conference. Fourth section deals with experimental analysis using ansys and then comparing it with the results obtained using technical calculation. Fundamentals and advancements in generator synchronizing systems michael j. Steam turbine valves are typically so reliable they are often overlooked. The effect of low cycle fatigue on the steam turbine casing is subject of interest in the third section.
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