The governor valve is a very important component in steam turbine, which can change the power output of the steam turbine by controlling the amount of the inlet steam. The service conditions of governor valve is very complicated, which should suffer high temperatures, high pressure, erosion, water induction and so on. As we all know the fatigue and creep can significantly reduce valve life. However, the damage due to governor valve seat interference fits is also very important for the units’ safety operation. A compromised interference fit can lead to significant valve leakage and possibly catastrophic seat failure. This article bases on a real case from a STP’s SC unit, which is operating in the South Asia market. Simulating the behavior of the valve seat under service conditions by numerical method, to find out the root cause of the interference fit failure and the operational advice for the unit running.

With the increasing demand of environmental protection, the development of highest efficiency fossil power plants to reduce the CO2 emissions has become a top priority. So the live steam parameters of AUSC unit will be increased to 700°C and 350bar. To achieve the desired operating hours at this temperature the application of nickel base materials is necessary for the main components such as rotors, inner casings and valves. Alloy 617 is selected for forged component. The creep behavior of Alloy 617 is quite different from Cr steel’s, the design experience of USC units can’t be completely adopted in the AUSC unit. The work presented in this paper, aims to predict the creep strain of Alloy 617 in AUSC turbine components. Several material models for creep in Alloy are compared. Base on the notched specimens’ experimental results, the models of the tertiary creep stage and the multiaxial behavior of turbine component are discussed.

With the flexibility operation demand of the plants, the load change becomes more and more often. The torsion loading due to load change becomes larger and more frequent. The influence of torsion loading frequency (the number of repeating cycles in a unit time) on the stress-strain behavior of component was numerically investigated under non-proportional loadings. A hollow cylinder specimen was chosen in this study. And three conditions of non-proportional loadings (Case1, Case2 and Case3) were chosen. The relationships between cyclic stress response and cyclic strain response were obtained for Case1, Case2 and Case3. The numerical results revealed that the distortion of stress-strain response curve was intensified with the increase of torsion loading frequency. The cyclic softening behaved in the first 2 cycles for the tension and torsion stress responses; however, the characterizations of the cyclic hardening and the cyclic softening for the material appeared after the starting 2 cycles. Furthermore, with the increase of cycle number and torsion loading frequency, there is a significant difference between the tension stress response and the torsion stress response.

Steam turbines need to be safer and more reliable when used in nuclear power plants. In order to ensure long-term reliability of nuclear power equipment, a high safety factor is usually adopted in the design of low-pressure (LP) inner casing of steam turbines. It not only leads to larger self-weight of LP outer casings and fundamental load, but also causes higher manufacturing and transportation costs. In this paper, the stress and deformation behaviors of the LP outer casings of steam turbines are first evaluated using the numerical finite element analysis. Then, two optimization design methods, size optimization and topology optimization are used to conduct the weight reduced optimization design of inner casing, in combination with the design standards, so that the structural efficiency and performance of LP inner casings are achieved. At the same time, the self-weight and related costs are also greatly reduced. This study proposes a more optimized structural design of LP inner casings of steam turbines, and it offers considerable economic benefits.

Nowadays, in order to accommodate electrical grids that include fluctuating supplies of green energy, more and more fossil power plants are increasingly required to start up and shut down frequently. The increased number of stress cycles leads to a significant reduction of lifetime. In this paper, numerous load cycles of steam turbine casing including various start up and shut down conditions were numerically investigated by using the finite element analysis (FEA). The total strain throughout the cycles was directly calculated by the elastic-plastic material model. The delta equivalent total strain was determined by rainflow count method, and the assessment of lifetime was evaluated.

Although stress corrosion cracking (SCC) and corrosion fatigue cracking can occur in many locations of nuclear steam turbines, most of them initiate at low pressure disc rim, rotor groove and keyway of the shrunk-on disc. For nuclear steam turbine components, long life endurance and high availability are very important factors in the operation. Usually nuclear power plants operating more than sixty years are susceptible to this failure mechanism. If SCC or corrosion fatigue happens, especially in rotor groove or keyway, it has a major influence on nuclear steam turbine life. In this paper, established methods for the SCC and corrosion fatigue-controlled life prediction of steam turbine components were applied to evaluating a new shrunk-on disc that had suffered local keyway surface damage during manufacture and loss of residual compressive stress.

Cogeneration has been identified as a key technical solution to improve environment, by reducing the impact of global climate change and reducing local emissions, such as particulates, sulphur and nitrogen oxides. In cogeneration, a certain pressure of steam has to be extracted from steam turbine. A mechanical device shall be used to maintain the pressure of the extracted steam. In this paper a new steam chest with valve used for cogeneration which is installed in the steam flow is introduced. Different amount of steam extractions need different valve openings. In order to obtain these several valve openings in typical operating conditions, CFD-program is used to simulate the flow path in the steam chest. The pressure distribution on the surface of valve disc can be calculated through CFD method, and corresponding steady aerodynamic forces and torques can be calculated by integral. Pulsatile flow will change the forces and moments acting on the valve discs with time constantly. Frequency spectrograms of the aerodynamic forces are obtained by using the fast Fourier transforms and compared to the characteristic frequencies of the valve disc obtained by mode analysis. For the purpose of validating the accuracy of CFD model, a test with test model scale of 1:5 has been designed. In the test, the pressure distribution on the valve disc surface and the flow field in the steam chest are acquired respectively by the method PSP (Pressure-Sensitive Paint) and PIV (Particle Image Velocimetry). CFD calculations and experimental results have been compared and it is shown that CFD calculations using K-ε turbulence model has satisfactory precision to calculate the pressure distribution, flow field and the torques.

High reliability and long life endurance are very important factors in the operation of large steam turbines for nuclear power plant (NPP). The low cycle fatigue (LCF) is necessary take into account problem in the design of turbine component. Thus the calculation method and assessment criterion of LCF are important for the design and development of the low pressure (LP) inner-casing. The main activity of this study was focus on the research of the low cycle fatigue in 26m 2 LP inner-casing of steam turbines for NPP, which is manufactured by Shanghai Electric Power Generation Equipment Co., Ltd: STP. And detailed calculation method and assessment criterion combined with FEA analysis, fatigue curve and linear cumulative damage theory are developed to judge the life of the LP inner-casing, The approach is applied in the process of the design work of large steam turbine inner-casing.