Failures of High-Temperature Critical Components in Combined Cycle Power Plants
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Failures of High-Temperature Critical Components in Combined Cycle Power Plants P. Kannan • K. S. Amirthagadeswaran T. Christopher • B. Nageswara Rao
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Submitted: 19 September 2012 / in revised form: 17 March 2013 / Published online: 17 April 2013 Ó ASM International 2013
Abstract This article highlights briefly the reported failure of critical parts and equipment in gas turbine, heat recovery steam generator, and steam turbine, in addition to the requirements of lifetime predictions for the high-temperature components in the combined cycle power plant (CCPP). For assessing fracture strength of flawed structural components in high-temperature environments, the first and foremost thing observed is to ascertain the reason for cracking. Special considerations are to be given in case of stress corrosion cracking, environmentally assisted cracking or bulk creep damage. Sensitivity analysis has to be performed to identify the influencing material properties and crack sizes on the load-bearing capacity of the structural component. An elastic–plastic criterion is examined by considering the fracture data of center crack tension specimens on several materials. Keywords Corrosion Creep Fatigue Fretting Gas turbines Pipelines Steam turbines
P. Kannan Rajiv Gandhi Combined Cycle Power Project, NTPC Ltd, Kayamkulam 690506, India K. S. Amirthagadeswaran Faculty of Mechanical Engineering, Government College of Technology, Coimbatore 641013, India T. Christopher Faculty of Mechanical Engineering, Government College of Engineering, Tirunelveli 627007, India B. Nageswara Rao (&) Faculty of Mechanical Engineering, School of Mechanical and Civil Sciences, KL University, Vaddeswaram 522502, India e-mail: [email protected]; [email protected]
Introduction India is the fifth largest producer of electricity in the world. Hydro-power and coal-based thermal power were the main sources of generating electricity prior to the development of nuclear power and combined cycle power plants (CCPPs). The installed capacity of power plants for the past six decades has increased to 205340.26 MW (as on 30 June 2012). At present thermal power generation dominates with 66.44% having a generation mix of 56.65% coal; and the capacity of the CCPP is 18903.05 MW (9.21%). Recent Fukushima Nuclear Power Plant disaster in Japan may turn the world toward CCPP to have safe and environment-friendly power generation [1]. Fuel switching, or the replacement of fossil fuels of high-carbon content with low-carbon fuels, is one of the principal methods suggested to reduce CO2 emissions in the near future. Since natural gas has lower-carbon content than coal or oil, switching from coal to gas as the primary fuel for electricity generation can result in 50% reduction of CO2 emissions per kWh. Gas- or liquid-based CCPPs burn fossil fuels cleanly when compared with the conventional technologies. NTPC Limited, erstwhile National Thermal Power Corporation (NTPC) Limited, is the largest state-owned power-generating company in India. Fo
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