Thermal Characterization of a Steam Turbine Casing Including Measuring of Adiabatic Wall Temperatures Using Proprietary Sensors

2021 ◽  
Author(s):  
Bernhard Valerian Weigel ◽  
Stefan Odenbach ◽  
Wieland Uffrecht ◽  
Thomas Polklas
Keyword(s):  
Steam Turbine ◽  
Measurement Data ◽  
Thermal Characterization ◽  
Steam Turbines ◽  
Adiabatic Wall ◽  
Cfd Validation ◽  
Thermally Induced ◽  
Steam Parameters ◽  
Cold Starts ◽  
Flexible Operation

Abstract Modern steam turbines must increasingly be designed for flexible operation. However an increasing amount of cold starts and load changes have a massive impact on fatigue resistance of the material. So the monitoring of thermal parameters of the casing is significant for checking thermally induced stresses and furthermore lifetime calculation. Additionally the measurement data is helpful for CFD validation reasons. This paper presents a new proprietary developed sensor setup and measurement results. The sensors are flush mounted into a steam turbine at different axial and circumferential locations in the recirculation area between the intermediate and the lower pressure turbine. Hence it is possible to detect temperatures, temperature gradients and heat flux in the part of the wall near the fluid. Moreover the field of temperature within the sensor can be modulated by powering an installed heater. So the adiabatic wall temperature can be identified. For measuring the temperature gradient, seven equidistant spaced thermocouples were used in difference circuit. Therefore two different types of thermocouples were applied. Both types have better transfer characteristics compared to a thermocouple of type K. High amplification enables monitoring of small differences in temperature. The temperature measures an integrated resistor thermometer. The sensors are applied on a real 12 MW industrial steam turbine with maximal live steam parameters of 400 °C and 30 bar. The measurements show various operation points and load changes.

Competitive Bidding by Surrogate Modeling of Steam Parameter Influence on the Attainable Start Numbers of Turbine Casings

2020 ◽  
Author(s):  
Marcel Seiler ◽  
Vitali Züch ◽  
Peter Dumstorff ◽  
Henning Almstedt
Keyword(s):  
Wall Temperature ◽  
Surrogate Model ◽  
Power Plants ◽  
Fe Model ◽  
Steam Turbines ◽  
Require Time ◽  
Steam Parameters ◽  
Fast Prediction ◽  
Main Steam ◽  
Flexible Operation

Abstract The continued expansion of fluctuating energy sources such as wind turbines and solar systems will increase the demand for more flexible operation modes of power plants. Especially steam turbines with all their components will have to sustain a higher amount of start-stop cycles in order to compensate for variations in wind and solar radiation. Besides the rotor, inner casings are an example for main steam turbine components which are strongly loaded by thermal cycles at each start and shut down procedure. A precise prediction of the attainable number of start-stop cycles enables a more flexible operation within the guaranteed lifetime. However, this would require time-consuming FE calculations for each power plant due to their specific steam parameters. In this paper, a physics based surrogate model is discussed for a fast prediction of permissible start-stop cycles at plant specific steam parameters. The correlation between the physical properties from the surrogate model (wall temperature difference and the resulting stresses) and the attainable number of start-stop cycles from the FE model is determined. A validation with a different inner casing design within a usual wall temperature range confirms the high accuracy level of the surrogate model compared to uncertainties like material scatter or casting tolerances. With the provided approach typically a higher number of starts can be efficiently calculated in the bidding phase compared to assuming only one conservative value for each turbine type or size. Furthermore, the steam parameters can be optimized for increasing the number of starts to the required value without additional and time-consuming FE calculations.

Unsteady Aerodynamics of Low-Pressure Steam Turbines Operating Under Low Volume Flow

2013 ◽  
Author(s):  
Benjamin Megerle ◽  
Timothy Stephen Rice ◽  
Ivan McBean ◽  
Peter Ott
Keyword(s):  
Unsteady Flow ◽  
Steam Turbine ◽  
Measurement Data ◽  
Unsteady Aerodynamics ◽  
Low Pressure ◽  
Rotating Stall ◽  
Stage Model ◽  
Steam Turbines ◽  
Multi Stage ◽  
Low Volume

Non-synchronous excitation under low volume operation is a major risk to the mechanical integrity of last stage moving blades (LSMBs) in low-pressure (LP) steam turbines. These vibrations are often induced by a rotating aerodynamic instability similar to rotating stall in compressors. Currently extensive validation of new blade designs is required to clarify whether they are subjected to the risk of not admissible blade vibration. Such tests are usually performed at the end of a blade development project. If resonance occurs a costly redesign is required, which may also lead to a reduction of performance. It is therefore of great interest to be able to predict correctly the unsteady flow phenomena and their effects. Detailed unsteady pressure measurements have been performed in a single stage model steam turbine operated with air under ventilation conditions. 3D CFD has been applied to simulate the unsteady flow in the air model turbine. It has been shown that the simulation reproduces well the characteristics of the phenomena observed in the tests. This methodology has been transferred to more realistic steam turbine multi stage environment. The numerical results have been validated with measurement data from a multi stage model LP steam turbine operated with steam. Measurement and numerical simulation show agreement with respect to the global flow field, the number of stall cells and the intensity of the rotating excitation mechanism. Furthermore, the air model turbine and model steam turbine numerical and measurement results are compared. It is demonstrated that the air model turbine is a suitable vehicle to investigate the unsteady effects found in a steam turbine.

Numerical Investigation of Exhaust Diffuser Performances in Low Pressure Turbine Casings

2011 ◽  
Author(s):  
Tadashi Tanuma ◽  
Yasuhiro Sasao ◽  
Satoru Yamamoto ◽  
Shinji Takada ◽  
Yoshiki Niizeki ◽  
...  
Keyword(s):  
Steam Turbine ◽  
High Performance ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Measurement Data ◽  
Boundary Layer Separation ◽  
Low Pressure ◽  
Tvd Scheme ◽  
Steam Turbines ◽  
Exhaust Hood

Low pressure (LP) exhaust hoods are an important component of steam turbines. The aerodynamic loss of LP exhaust hoods is almost the same as those of the stator and rotor blading in LP steam turbines. Designing high performance LP exhaust hoods should lead further enhancement of steam turbine efficiency. This paper presents the results of exhaust hood computational fluid dynamics (CFD) analyses using last stage exit velocity distributions measured in a full-scale development steam turbine as the inlet boundary condition to improve the accuracy of the CFD analysis. One of the main difficulties in predicting the aerodynamic performance of the exhaust hoods is the unsteady boundary layer separation of exhaust hood diffusers. A highly accurate unsteady numerical analysis is introduced in order to simulate the diffuser flows in LP exhaust hoods. Compressible Navier-Stokes equations and mathematical models for nonequilibrium condensation are solved using the high-order high-resolution finite-difference method based on the fourth-order compact MUSCL TVD scheme, Roe’s approximate Riemann solver, and the LU-SGS scheme. The SST turbulence model is also solved for evaluating the eddy viscosity. The computational results were validated using the measurement data, and the present CFD method was proven to be suitable as a useful tool for determining optimum three-dimensional designs of LP turbine exhaust diffusers.

The Influence of Cooling Flows on the Operating Conditions of the Ultra-Supercritical Steam Turbine Components

2010 ◽  
Author(s):  
Wojciech Kosman
Keyword(s):  
Numerical Modeling ◽  
Steam Turbine ◽  
Power Plants ◽  
Measurement Data ◽  
Test Stand ◽  
Operating Conditions ◽  
Temperature Fields ◽  
Inlet Section ◽  
Steam Turbines ◽  
Cooling Flows

This paper presents the results of the analysis on the heat transfer in the inlet section of an ultra-supercritical steam turbine. Such power generating units become the foundation of new coal-fired power plants. The monitoring of their operation is in many aspects similar to the traditional, sub-critical steam turbines. However, higher live and reheat steam parameters result in several key differences, which must be taken into the consideration when assessing the thermal and strength states of the turbines main components for the diagnostic supervision. One of the main differences is the presence of the cooling and designs specific for ultra-supercritical steam turbines, which aim to protect their components against overheating. The research described in this paper investigates the inlet section of the turbines, which is the area exposed to the highest thermal loads. The scope of the research includes both, numerical modeling and laboratory testing. A test stand has been built for the analysis of the flows in the inlet section. Cooling flows are under special attention here as their temperature field is coupled to the temperature fields of the turbine components (the rotor and the inner casing) due to the relatively small amount of the coolant. The paper provides detailed description of the test stand and some early measurement results, which involve the operation with cooling. Also the numerical modeling results are shown and compared to the measurement data.

Creep Deformation of High Pressure Steam Turbine Part

2015 ◽  
Vol 732 ◽  
pp. 187-190
Author(s):  
František Straka ◽  
Pavel Albl ◽  
Pavel Pánek
Keyword(s):  
High Pressure ◽  
High Temperature ◽  
Steam Turbine ◽  
Creep Deformation ◽  
Steam Turbines ◽  
High Pressure Turbine ◽  
High Pressure Steam ◽  
Pressure Steam ◽  
Temperature Levels ◽  
Steam Parameters

Steam turbines are complex rotating machines working at high pressure and high temperature levels. Their high-pressure parts, which are subjected to the highest steam parameters, are most affected by these conditions and may suffer from creep deformation. Permanent changes in geometry become visible in high-pressure turbine casings when they are disassembled after certain time in operation.

scholarly journals Energy Loss Analysis at the Gland Seals of a Marine Turbo-Generator Steam Turbine

2020 ◽  
Vol 14 (1) ◽  
pp. 19-26 ◽  
Author(s):  
Lino Kocijel ◽  
Igor Poljak ◽  
Vedran Mrzljak ◽  
Zlatan Car
Keyword(s):  
Steam Turbine ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Measurement Data ◽  
Energy Losses ◽  
Operating Parameters ◽  
Steam Turbines ◽  
Turbo Generator ◽  
Gland Seal

The paper presents an analysis of marine Turbo-Generator Steam Turbine (TGST) energy losses at turbine gland seals. The analyzed TGST is one of two identical Turbo-Generator Steam Turbines mounted in the steam propulsion plant of a commercial LNG carrier. Research is based on the TGST measurement data obtained during exploitation at three different loads. The turbine front gland seal is the most important element which defines TGST operating parameters, energy losses and energy efficiencies. The front gland seal should have as many chambers as possible in order to minimize the leaked steam mass flow rate, which will result in a turbine energy losses’ decrease and in an increase in energy efficiency. The steam mass flow rate leakage through the TGST rear gland seal has a low or negligible influence on turbine operating parameters, energy losses and energy efficiencies. The highest turbine energy efficiencies are noted at a high load – on which TGST operation is preferable.

Numerical Study of Reynolds Number Effects on Steam Turbine Performance

2015 ◽  
Author(s):  
J. H. Cheon ◽  
P. Milčák ◽  
M. Šťastný
Keyword(s):  
Surface Roughness ◽  
Reynolds Number ◽  
Steam Turbine ◽  
Numerical Study ◽  
Measurement Data ◽  
Operating Regime ◽  
Steam Turbines ◽  
Flow Angle ◽  
Turbine Performance ◽  
Reynolds Number Effects

The performance of blade profiles was examined with three linear cascade blades which represent hub, mid-span and tip section using numerical analysis. The Reynolds number was varied from 10,000 to 10,000,000 to capture the operating regime for typical steam turbines. Twelve different levels of surface roughness on the same profile were calculated using the roughness model in ANSYS-CFX. The ratios of surface roughness to chord length are in the range of ks/c = 4.2 × 10–5 ∼ 8.3 × 10−4. The CFD result was compared to Reynolds number correction curves from published literature (AMDC-KO, Aungier, Craig & Cox, Traupel, Sanders and Denton) and available measurement data. Based on these comparisons, a Reynolds number correction curve was properly selected for the estimation of steam turbine performance. Also, it was found that Reynolds number with hydraulically smooth surfaces has little influence on the change in flow angle and roughness does not significantly change outlet flow angle.

Unsteady Aerodynamics of Low-Pressure Steam Turbines Operating Under Low Volume Flow

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Benjamin Megerle ◽  
Ivan McBean ◽  
Timothy Stephen Rice ◽  
Peter Ott
Keyword(s):  
Unsteady Flow ◽  
Steam Turbine ◽  
Measurement Data ◽  
Unsteady Aerodynamics ◽  
Low Pressure ◽  
Development Project ◽  
Rotating Stall ◽  
Steam Turbines ◽  
Blade Vibration ◽  
Low Volume

Nonsynchronous excitation under low volume operation is a major risk to the mechanical integrity of last stage moving blades (LSMBs) in low-pressure (LP) steam turbines. These vibrations are often induced by a rotating aerodynamic instability similar to rotating stall in compressors. Currently extensive validation of new blade designs is required to clarify whether they are subjected to the risk of not admissible blade vibration. Such tests are usually performed at the end of a blade development project. If resonance occurs a costly redesign is required, which may also lead to a reduction of performance. It is therefore of great interest to be able to predict correctly the unsteady flow phenomena and their effects. Detailed unsteady pressure measurements have been performed in a single stage model steam turbine operated with air under ventilation conditions. 3D computational fluid dynamics (CFD) has been applied to simulate the unsteady flow in the air model turbine. It has been shown that the simulation reproduces well the characteristics of the phenomena observed in the tests. This methodology has been transferred to more realistic steam turbine multistage environment. The numerical results have been validated with measurement data from a multistage model LP steam turbine operated with steam. Measurement and numerical simulation show agreement with respect to the global flow field, the number of stall cells and the intensity of the rotating excitation mechanism. Furthermore, the air model turbine and model steam turbine numerical and measurement results are compared. It is demonstrated that the air model turbine is a suitable vehicle to investigate the unsteady effects found in a steam turbine.

Fault diagnosis method of peak-load-regulation steam turbine based on improved PCA-HKNN artificial neural network

2021 ◽  
pp. 1748006X2110105
Author(s):  
Yifan Wu ◽  
Wei Li ◽  
Deren Sheng ◽  
Jianhong Chen ◽  
Zitao Yu
Keyword(s):  
Neural Network ◽  
Fault Diagnosis ◽  
Steam Turbine ◽  
Power Plants ◽  
Peak Load ◽  
Clean Energy ◽  
Steam Turbines ◽  
Peak Shaving ◽  
Diagnosis Method ◽  
Load Regulation

Clean energy is now developing rapidly, especially in the United States, China, the Britain and the European Union. To ensure the stability of power production and consumption, and to give higher priority to clean energy, it is essential for large power plants to implement peak shaving operation, which means that even the 1000 MW steam turbines in large plants will undertake peak shaving tasks for a long period of time. However, with the peak load regulation, the steam turbines operating in low capacity may be much more likely to cause faults. In this paper, aiming at peak load shaving, a fault diagnosis method of steam turbine vibration has been presented. The major models, namely hierarchy-KNN model on the basis of improved principal component analysis (Improved PCA-HKNN) has been discussed in detail. Additionally, a new fault diagnosis method has been proposed. By applying the PCA improved by information entropy, the vibration and thermal original data are decomposed and classified into a finite number of characteristic parameters and factor matrices. For the peak shaving power plants, the peak load shaving state involving their methods of operation and results of vibration would be elaborated further. Combined with the data and the operation state, the HKNN model is established to carry out the fault diagnosis. Finally, the efficiency and reliability of the improved PCA-HKNN model is discussed. It’s indicated that compared with the traditional method, especially handling the large data, this model enhances the convergence speed and the anti-interference ability of the neural network, reduces the training time and diagnosis time by more than 50%, improving the reliability of the diagnosis from 76% to 97%.

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