Wednesday, May 6, 2020

Sayano

Sayano-Shushenskaya Hydroelectric Power Station Accident Essay 2. 0 Root Factors On August 17th, 2009, the Sayana-shushenskaya powerplant suffered a massive accident that resulted in the flooding of the engine and turbine rooms and two electric generators to explode underwater due to short circuit. Due to fatigue caused by extensive vibrations, the pins holding turbine number 2 breaks apart. Water rushing down the penstocks forces the 1500 ton turbine through the powerhouse floor launching it 50 feet into the air. A fountain of water flowing at 67,600 gallons per second destroys the roof and floods the turbine hall causing power failures and short ircuit to turbines 7 and 9. . 1 Design Process Factors Shortly after its installation, turbine number 2 had been experiencing problems due to defects in seals and shaft vibrations. In March 2000, a complete overhaul on turbine 2 was performed where cavities of 12 mm in depth and cracks up to 130mm in length found and repaired. Despite these efforts, turbine number 2 continued to have problems resultin g in further repairs in 2005 and Prior to the accident, the turbine was undergoing scheduled maintenance from January through March 2009. During the maintenance period, the turbine blades were welded due to ppearance of cracks and cavities caused by long period of operation. The turbine was also equipped with a new electro hydraulic speed regulator supplied by Promavtomatika company . lt was resynchronized to the grid on March 16 although the vibrations remained high but did not exceed specifications. The vibrations increased between April and July exceeding the specifications causing the unit to be taken offline until August 16th when the Bratsk fire forced managers to push the turbine into service again. LMZ, the St. Petersburg metalworks that manufactured the turbines gave it a 30 year service lifespan. Turbine 2s age on August 17th was 29 years 10 months . Turbine 2 was started and switched to regulating mode due to the Bratsk fire. Data on turbine 2s start-up and operation period through to the failure time is recorded in Figure 5. Figure : Operating condition of Turbine 2 The turbine models are RO-230/833-V-677. As shown in Figure 5, they have very narrow recommended zone of power control. Excessive vibrations occur when it is being operated with a power setting out of the recommended zone or when it is in transitioning through the not recommended zone. Furthermore, when turbine 2 was hastily pushed back into service, the vibrations were unusually high and continued to rise. Figure 6 bellow shows data of the vibration from the plant logs. The log data shows that the bearing vibration level of turbine 2 increased exponentially and exceeded the values of other turbines by more than fourfold. At the period of the accident vibrations were at 840pm when its maximum acceptable value is 160 gm. Figure 6 also shows that turbine 2 was operating with vibration levels above 600 pm for a long period while the rest of the turbines were at around 00 pm. This led to the equipment fatigue, primarily in the turbine anchor bolts as a result of the extensive vibration causing it to finally reach the point of failure. 4. 2 Human Factors Human factor also played its part in causing the accident at the powerplant. If small details that were overlooked and ignored were fixed instead, the accident could have been averted. For instance, when turbine 2 was under maintenance from January to March 2009, after the repairs on the turbine were completed, the turbine wheel was not properly rebalanced before commencing operation . This might have contributed to why the turbine continued to vibrate extensively during April and July leading it to be halted until August 16. However, turbine 2 was hastily pushed back into operation due to the Bratsk plant fire. The Siberian Unified Dispatching Control Centre (UDCC) made the decision to start turbine 2 at the Sayano-shushenskaya plant and switch it to regulating mode immediately as cover for the Bratsk plant even though it was halted due to the extensive vibrations. This means that it was subjected to even more intense cycling service due to the flow of water, forcing it hrough several passes through the not recommended zones of power output as seen in Figure 5. Furthermore, these turbine models have a very fine working band at high efficiency conditions. To Build a Fire EssayThey should be programmed to follow specific rules that do not depend on manual interaction to shut down a faulty unit. This device could act as an emergency shutdown in case of excessive vibrations. The turbines should not be allowed to operate in the not recommended zone for two cavities. 6. 2 Human Resources The installation and maintenance of all turbines and equipment should be monitored and accepted by the primary equipment manufacturers and not by the powerplant chiefs as before. This is because the manufacturers would have more knowledge of how to deal with defects in the systems. The directors and management board should make sure to never neglect and ignore even a small problem with the operation. They should ensure the turbines be put offline at the first indication of abnormalities. 6. 3 Safety Health The main improvement that can be made is for the directors of the plant to place more value on human and equipment safety than on the economics of power production. Staff should be given sufficient training and guidelines to handle emergency situation. They should be given sufficient authority to make crucial decisions in the absence of a superior. Finally, a fully funded extensive inspection, repair and maintenance program should be put into action more often. Furthermore, andom inspections by an independent organization that is familiar to safety hazards should be encouraged. 7. 0 Conclusion To summarize this report, the accident at the Sayano-shushenskaya hydroplant was caused mainly by poor management and technical flaws. It could have been avoided if a more tight maintenance had been implemented. Also staff working at the powerplant should have been more aware about problems with turbine number 2 especially since it has been giving problems since the dam was built. Tighter safety rules and safety inspections should be made in the future to avoid this catastrophic event from repeating itself again. . 0 Reference 1 . Russell W. Ray. (2010). Restoring Sayano-shushenskaya. Available: http:// www. renewableenergyworld. com/rea/news/article/2010/03/restoring-sayano- shushenskaya. Last accessed 31110/2013. 2. 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Available: http://www. popularmechanics. com/technology/engineering/ onzo/4344681. Last accessed 7/11/2013. 7. EFO staff. (March 17, 2012). ayano- Shushenskaya Hydroelectric Power Station Accident. Available: http:// 5, 2009). Negligence a Factor in Russian Power Plant Accident That Killed 75. Available: http://www. insurance]ournal. com/news/international/ 2009/10/05/104297. htm. Last accessed 6/11/2013. 9. RusHYdro. (30 August 2009). Valery Kyari appointed director of the Sayano-shushensk aya HPP. Available: http:// www. rushydro. ru/press/news/7771 . html. Last accessed 9/11/2013 10. RusHydro. 0. Reconstruction of the Sayano-shushenskaya HPP named after P. S. Neporozhniy. Available: http://www. eng. rushydro. u/industry/invest/key_pro]ects/ reconstruction_of_the_sayano_shushenskaya_hpp_named_after_p_s_neporozhniy/ . Last accessed 9/11/2013. 11. Denisov,R. (August 18,2009). Insulating oil spreads along Siberian river after hydro disaster . 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