Models of control valve and actuation system for dynamics analysis of steam turbines

2017 ◽  
Vol 207 ◽  
pp. 208-217 ◽  
Author(s):  
Maddalena Pondini ◽  
Valentina Colla ◽  
Annamaria Signorini
Keyword(s):  
Control Valve ◽  
Dynamics Analysis ◽  
Steam Turbines ◽  
Actuation System

A Throttle Control Valve for Steam Turbines Operating with Large Volumetric Flowrates of Working Fluids

2018 ◽  
Vol 65 (8) ◽  
pp. 568-574
Author(s):  
A. E. Zaryankin ◽  
I. P. Lavyrev ◽  
V. V. Shchaulov ◽  
M. A. Cherkasov
Keyword(s):  
Control Valve ◽  
Steam Turbines ◽  
Working Fluids

Investigation on Flow Characteristics and Stability of Control Valves for Steam Turbines

2008 ◽  
Author(s):  
Guanwei Liu ◽  
Shunsen Wang ◽  
Hui Guo ◽  
Jingru Mao ◽  
Zhenping Feng ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pressure Ratio ◽  
Control Valve ◽  
Operating Conditions ◽  
Flow Coefficient ◽  
Outlet Section ◽  
Steam Turbines ◽  
Control Valves ◽  
Structure Of Flow ◽  
Valve Disc

Through-flow capability and flow stability of some steam turbine control valves were studied by experimental investigation and numerical simulation. Based on the analysis of thermodynamic process in control valve, the relationship of flow coefficient, area ratio of valve outlet section to seat diameter section, pressure ratio and total pressure loss coefficient was deduced, and the expression of polytropic exponent was obtained. The relative deviations between formula results and experimental results are within 3%. Both expressions can be used for design and optimization to determine control valve parameters quantitatively. The results of 3D numerical simulation indicate that the topological structure of flow fields in all control valves is similar. The results of valve stability show that the airflow force acted on the valve disc depends on the vortex strength of flow around valve stem bush and valve disc, the asymmetric transonic impinging jet under the valve disc and the diffusing action. The valve operates steadily when the inlet and outlet Mach number are less than 0.15. As the unload degree is about 85%, stem vibrates at the operating conditions when pressure ratio is less than 0.8 and opening ratio is from 10% to 18%. A multihole annular orifice can make flow steady at all operating conditions.

Reliability and Availability Prediction of Main Stop Valve and Control Valve Systems of Steam Turbines

2011 ◽  
Author(s):  
Jinyuan Shi ◽  
Yong Wang ◽  
Xiaoping Zhong ◽  
Zhicheng Deng
Keyword(s):  
Prediction Method ◽  
Control Valve ◽  
Design Stage ◽  
Steam Turbines ◽  
Stop Valve ◽  
Control Valves ◽  
Reliability Block Diagrams ◽  
And Control ◽  
The Mathematical Model ◽  
Reliability And Availability

A method for the reliability and the availability prediction of main stop valve and control valve systems of steam turbines is presented. The calculation models for the reliability and the availability of series, parallel and series-parallel systems of main stop valves and control valves are introduced. The reliability block diagrams, the availability block diagrams, formulas for the reliability prediction and the availability prediction of systems with 2 main stop valves and 2 control valves, 2 main stop valves and 4 control valves, 2 main stop valves and 6 control valves, 4 main stop valves and 4 control valves are given together with some examples. The mathematical model for the reliability and the availability prediction method of main stop valve and control valve systems of steam turbine is simple and the physical meaning is definite. The reliability and availability of main stop valve and control valve systems can be quantitatively already calculated and improved during the design stage. A basis is thus provided for the reliability and the availability design of main stop valve and control valve systems of steam turbines.

scholarly journals Assessment of Residual Service Life of Cast Bodies of Control Valves of 220 MW Power Units

2020 ◽  
Vol 23 (4) ◽  
pp. 22-28
Author(s):  
Olha Yu. Chernousenko ◽  
◽  
Dmytro V. Ryndiuk ◽  
Vitalii A. Peshko ◽  
◽  
...  
Keyword(s):  
Service Life ◽  
Control Valve ◽  
Steam Turbines ◽  
Operating Life ◽  
Control Valves ◽  
Intermediate Pressure ◽  
Operating Modes ◽  
Residual Operating Life ◽  
Start Ups ◽  
Total Damage

In the regulatory documents of the Ministry of Energy and Coal Industry of Ukraine, the beyond-design operating life of the high-energy equipment of 220 MW power units is limited to the operating life of 220 thousand hours and 800 start-ups. To date, the high-temperature cast bodies of the control valves for the high- and intermediate-pressure cylinders of the K-200-130 200 MW steam turbines of DTEK Lugansk TPP have operated about 305–330 thousand hours with the total number of start-ups from 1438 to 1704, which exceeded the beyond-design service life characteristics. Therefore, it is necessary to assess the residual operating life of the control valve bodies of the high- and intermediate-pressure cylinders of K-200-130 steam turbines in order to determine the possibility of their further operation. These calculations were carried out on the basis of our earlier studies of the thermal and stress-strain states of cast turbine equipment. This paper establishes the values of stress intensity amplitudes, the values having been reduced to a symmetric loading cycle for the most typical variable operating modes. Using the experimental low-cycle fatigue curves for the 15Kh1M1FL steel, we established the values of the permissible number of start-ups and the cyclic damage accumulated in the base metal. We also determined the value of the static damage accumulated in the course of stationary operating modes according to our previously obtained experimental data on the long-term strength of the 15Kh1M1FL steel. The calculations showed that the total damage to the control valve bodies of the K-200-130 steam turbine of power unit 15 of DTEK Lugansk TPP is 97 and 98%. The residual operating life of the metal of the control valves of high-pressure cylinders is practically exhausted, being equal to 10 thousand hours. The residual life of the control valves of intermediate- pressure cylinders is 7 thousand hours, i.e. it is also practically exhausted, with safety factors for the number of cycles and strains at the level of 5 and 1.5, as well as the permissible 370,000 operating hours of the metal. With an increase in the permissible operating life of the metal to 470 thousand hours, according to experimental studies of Igor Sikorsky KPI, the total damage to the metal of cast valve bodies is reduced to 80%, and the residual metal life increases to 79,000 h and 75,000 h for the control valves of the high- and intermediate-pressure cylinders, respectively.

scholarly journals Analysis of the Unsteady Flow Field in a Steam Turbine Control Valve using Spectral Proper Orthogonal Decomposition

2021 ◽  
Vol 6 (2) ◽  
pp. 11
Author(s):  
Christian Windemuth ◽  
Martin Lange ◽  
Ronald Mailach
Keyword(s):  
Proper Orthogonal Decomposition ◽  
Turbulence Modeling ◽  
Control Valve ◽  
Electrical Energy ◽  
Orthogonal Decomposition ◽  
Steam Turbines ◽  
Unstable Flow ◽  
Turbulent Structures ◽  
Part Load ◽  
Proper Orthogonal

A significant share of the conversion of thermal into electrical energy is realized by steam turbines. Formerly designed for continuous operation, today’s requirements include extended part load operation that can be accompanied by highly unstable flow conditions and vibrations within the control valve of the turbine. The prediction of the flow at part load conditions requires large computational efforts with advanced turbulence modeling in order to compute the flow at a reasonable accuracy. Due to the unsteadiness of the flow, the evaluation of the numerical results itself is a major challenge. The turbulent structures require statistical approaches, of which the use of Spectral Proper Orthogonal Decomposition (SPOD) has proven itself as a powerful method. Within this paper, the application of the method on a critical operating point with a temporal excitation of pressure oscillations observed in the experiments with dry air is presented. Using SPOD, the dominating flow phenomena were isolated and flow structures visualized.

A Precise Full-Dimensional Design System for Multistage Steam Turbines: Part II — Key Technologies for Blade and Non-Blade Components, Engineering Application and Updating

2007 ◽  
Author(s):  
Xinzhong Xu ◽  
Kepeng Xu ◽  
Baoqing Li ◽  
Qing Chen ◽  
Hongde Jiang
Keyword(s):  
Power Plants ◽  
Performance Test ◽  
Mechanical Design ◽  
Design Method ◽  
Engineering Application ◽  
Control Valve ◽  
Fem Analysis ◽  
Design System ◽  
Steam Turbines ◽  
Key Technologies

In this part of present paper the key technologies for steam turbine blade and non-blade components developed by using the precise, full-dimensional (PFD) system is described firstly. For blade components advanced aerodynamic concept and design method for customized after-loaded profile, compound-lean blade, tandem cascade, contoured endwall, and solid particle erosion protection for HP and IP first nozzle have been developed. For non-blade component including main steam inlet/control valve, LP exhaust hood, packing seal and cavity flow, casing opening and condenser, new aerodynamic and mechanical design has been developed. New blade and non-blade components were experimentally and numerically investigated to verify its performance. Finite element method (FEM) analysis for all key components is also illustrated in this paper. Secondly the approach of validation and updating for the PFD system is introduced. Based on a large amount of on-site performance test data in power plants the statistic accuracy for the PFD system is given. It shows that in comparison with conventional F3D design methodology another 1.5-2 percent of HP and IP overall section efficiency improvement has been achieved.

Investigation of Unsteady Pressure Fluctuations in a Simplified Steam Turbine Control Valve

2020 ◽  
Author(s):  
Christian Windemuth ◽  
Martin Lange ◽  
Ronald Mailach
Keyword(s):  
Steam Turbine ◽  
Power Plants ◽  
Pressure Fluctuations ◽  
Control Valve ◽  
Steam Turbines ◽  
Unsteady Forces ◽  
Part Load ◽  
Large Pressure ◽  
Head Surface ◽  
Flow Through

Abstract Steam turbines are among the most important systems in commercial and industrial power conversion. As the amount of renewable energies increases, power plants formerly operated at steady state base load are now experiencing increased times at part load conditions. Besides other methods, the use of control valves is a widely spread method for controlling the power output of a steam turbine. In difference to other throttling approaches, the control valve enables fast load gradients as the boiler can be operated at constant conditions and allows a quicker response on variable power requirements. At part load, a significant amount of energy is dissipated across the valve, as the total inlet pressure of the turbine is decreased across the valve. At these conditions, the flow through the valve becomes trans- and supersonic and large pressure fluctuations appear within the downstream part of the valve. As a result, unsteady forces are acting on the valve structure and vibrations can be triggered, leading to mechanical stresses and possible failures of the valve. Besides more complex valve geometries, a spherical valve shape is still often used in smaller and industrial steam turbines. Because of the smooth head contour, the flow is prone to remain attached to the head surface and interact with the flow coming from the opposite side. This behaviour is accompanied by flow instabilities and large pressure fluctuations, leading to unsteady forces and possible couplings with mechanical frequencies. The spherical valve shape was therefore chosen as the experimental test geometry for the investigation of the unsteady flow field and fluid-structure-interactions within a scaled steam turbine control valve. Using numerical methods, the test valve is investigated and the time dependent pressure distribution in the downstream diffuser is evaluated. The evolution of the flow stability will be discussed for different pressure ratios. Pressure signals retrieved from the control valve test rig will be used to compare the numerical results to experimental data.

New Steam Turbine Test Vehicle for the Verification of Improved Efficiency Power Generation Steam Turbines

2000 ◽  
Author(s):  
Lawrence D. Willey ◽  
James R. Maughan ◽  
J. Michael Hill ◽  
Dennis J. Walsh
Keyword(s):  
Power Generation ◽  
Steam Turbine ◽  
New Product Development ◽  
Control Valve ◽  
New Product ◽  
Product Development Process ◽  
Test Facility ◽  
Steam Turbines ◽  
Test Vehicle ◽  
Reduced Pressure

Abstract The worldwide demand for electricity is continually increasing. Deregulation in the power generation business is driving rapid changes in the global energy market. This results in higher premiums on steam turbine efficiency and opportunities to structure several new Steam Turbine products to meet these challenging requirements. The “Dense Pack” high pressure section replacement and offering is one of the newest advanced designs to address these needs by delivering more power for the least amount of fuel. The intense competition to serve the electric power utility industry combined with the drive for new product introductions to be of the highest development life-cycle quality demands that verification of performance benefits be established very early in the new product development process. To answer this and establish pre-field installation credibility with customers, a new multi-stage Steam Turbine Test Vehicle (STTV) has been designed and constructed. The turbine faithfully models a typical, 4-admission, large utility steam turbine and preserves geometric and flow similarity while operating at reduced pressure. The basic train is comprised of a nominal 3.5 MW (4700 hp) test turbine, a 5:1 speed reducing load gear, and two tandem 3.0 MW (4000 hp) dynamometers. The thermodynamic cycle is straight through superheated steam entering the turbine through a turbine bowl pressure regulator control valve and exhausted to the atmosphere via a back pressure control valve and roof-mounted silencer. A rigorous Design for Six Sigma (DFSS) process was used to establish the test turbine facility and to ensure all of the new product program objectives were met. A detailed description of the facility is given with discussion of the major sub-systems, prototypical model hardware, unique steampath instrumentation, and the test procedures used to ensure accurate, repeatable data. The timeline for accomplishing the design, construction, and early testing is chronicled. Key test results are summarized including baseline testing to validate the new test facility, testing of the “Dense Pack” aerodynamic design methodology for power generation steam turbines, and the performance evaluation of developments such as new shaft, advanced aerodynamics and bucket tip seals. In addition to developing the new design technologies and verifying their predicted efficiency increases, the Steam Turbine Test Vehicle is key for conducting Form-Fit-Function studies. Model hardware built using the standard manufacturing methods and materials intended for production parts provides invaluable insight ahead of finalizing production specifications. New features such as advanced seals and Integral Cover Buckets (ICB) benefit from being more thoroughly understood in terms of assembly and procedures ahead of new product production.

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