scholarly journals Influence of Intercept Valves on Control of Multiple Stages Steam Turbines During the Switching into the Island Operation

2015 ◽  
Vol 66 (2) ◽  
pp. 103-107
Author(s):  
Ladislav Laštovka ◽  
Pavla Hejtmánková
Keyword(s):  
High Pressure ◽  
Control System ◽  
Steam Turbine ◽  
Dynamic Load ◽  
The Other ◽  
Steam Turbines ◽  
Electrical Grid ◽  
Operation Status ◽  
Hydraulic Valves ◽  
Multiple Stages

Abstract This paper presents control of a multiple stages steam turbine which is switched into the island operation. The frequency in an electrical grid is stated on nominal value which is in UCTE grid 50 Hz. When deviation of frequency is higher then 0.2 Hz, the switching of particular steam units into the island operation is only the chance how to maintain the supply of, at least, some small grids. The other possibility how to keep power units in operation, to be prepared for the next synchronization to the grid, is to switch them to operation status in which they supply only their self-consumption. This change of the operating state is the most dynamic load change for the control system of the unit. The multiple stages turbines are equipped with high pressure hydraulic valves for steam turbine governing. Influence of the intercept valve on steam turbine control during the switching process into the island operation is examined in Matlab Simuling software.

Using CFD to Enhance the Preliminary Design of High-Pressure Steam Turbines

2013 ◽  
Author(s):  
Juri Bellucci ◽  
Federica Sazzini ◽  
Filippo Rubechini ◽  
Andrea Arnone ◽  
Lorenzo Arcangeli ◽  
...  
Keyword(s):  
High Pressure ◽  
Steam Turbine ◽  
Design Tool ◽  
Tip Clearance ◽  
Large Set ◽  
Preliminary Design ◽  
Steam Turbines ◽  
High Pressure Steam ◽  
Wide Range ◽  
Pressure Steam

This paper focuses on the use of the CFD for improving a steam turbine preliminary design tool. Three-dimensional RANS analyses were carried out in order to independently investigate the effects of profile, secondary flow and tip clearance losses, on the efficiency of two high-pressure steam turbine stages. The parametric study included geometrical features such as stagger angle, aspect ratio and radius ratio, and was conducted for a wide range of flow coefficients to cover the whole operating envelope. The results are reported in terms of stage performance curves, enthalpy loss coefficients and span-wise distribution of the blade-to-blade exit angles. A detailed discussion of these results is provided in order to highlight the different aerodynamic behavior of the two geometries. Once the analysis was concluded, the tuning of a preliminary steam turbine design tool was carried out, based on a correlative approach. Due to the lack of a large set of experimental data, the information obtained from the post-processing of the CFD computations were applied to update the current correlations, in order to improve the accuracy of the efficiency evaluation for both stages. Finally, the predictions of the tuned preliminary design tool were compared with the results of the CFD computations, in terms of stage efficiency, in a broad range of flow coefficients and in different real machine layouts.

Validation of Advanced Steam Turbine Technology: A Case Study of an Ultra Super Critical Steam Turbine Power Plant

2011 ◽  
Author(s):  
Rainer Quinkertz ◽  
Thomas Thiemann ◽  
Kai Gierse
Keyword(s):  
High Pressure ◽  
Power Plant ◽  
Steam Turbine ◽  
Power Plants ◽  
High Efficiency ◽  
State Of The Art ◽  
Cooling System ◽  
Operational Experience ◽  
Internal Cooling ◽  
Steam Turbines

High efficiency and flexible operation continue to be the major requirements for power generation because of the benefits of reduced emissions and reduced fuel consumption, i.e. reduced operating costs. Ultra super critical (USC) steam parameters are the basis for state of the art technology of coal fired power plants with highest efficiency. An important part of the development process for advanced steam turbines is product validation. This step involves more than just providing evidence of customer guaranteed values (e.g. heat rate or electric output). It also involves proving that the design targets have been achieved and that the operational experience is fed back to designers to further develop the design criteria and enable the next step in the development of highly sophisticated products. What makes product validation for large size power plant steam turbines especially challenging is the fact that, due to the high costs of the required infrastructure, steam turbine manufacturers usually do not have a full scope / full scale testing facility. Therefore, good customer relations are the key to successful validation. This paper describes an extensive validation program for a modern state of the art ultra supercritical steam turbine performed at an operating 1000 MW steam power plant in China. Several measuring points in addition to the standard operating measurements were installed at one of the high pressure turbines to record the temperature distribution, e.g. to verify the functionality of the internal cooling system, which is an advanced design feature of the installed modern high pressure steam turbines. Predicted 3D temperature distributions are compared to the actual measurements in order to verify and evaluate the design rules and the design philosophy applied. Conclusions are drawn regarding the performance of modern 3D design tools applied in the current design process and an outlook is given on the future potential of modern USC turbines.

Aerodynamic Flutter of Turbine Brush Seals

2017 ◽  
Author(s):  
Samuel J. Borgueta ◽  
Nicholas R. Bach ◽  
Jared J. Correia ◽  
Brendan G. J. Egan ◽  
Joshua S. Horton ◽  
...  
Keyword(s):  
High Pressure ◽  
Steam Turbine ◽  
Reynolds Numbers ◽  
Working Fluid ◽  
Steam Turbines ◽  
High Pressure Steam ◽  
Modes Of Failure ◽  
Brush Seal ◽  
Pressure Steam ◽  
Brush Seals

With global energy demands continually growing and environmental impacts a major concern in power production, maximizing the efficiencies of power plants is of top priority. EthosEnergy2 has sponsored a project at the University of Massachusetts Dartmouth to study and analyze the brush seals in steam turbines in pursuit of increasing steam turbine thermodynamic efficiency. Brush seals are incorporated circumferentially around the turbine blades in their housing. The brush seals provide a very minimal clearance height that compensates for start-up rotor deviation and minimizes high-pressure steam blow-by around the edges of the blades. Brush seals minimize the clearance height between the blades and housing, which allows the turbine to produce more work. However, overtime brush seals can be damaged, greatly reducing efficiency. The seals that are repeatedly showing excessive wear and damage, occur in the high-pressure sections of steam turbines with high Reynolds numbers. The bristle breakdown is attributed to high Reynolds numbers and aerodynamic flutter. The purpose of this research is to design a prototype and empirically model steam turbine conditions with air to map out the fluid-solid interaction, determine the modes of bristle failure, and ultimately reproduce and record bristle flutter. A pressure vessel and pressure system was designed to test linear strips of brush seals with air as the working fluid. The pressure vessel accommodates varying clearance heights to identify the correlation of clearance height and the effects on fluid flow. The system also incorporates a high-speed camera that can capture the phenomena of flutter, precisely identify the modes of failure, and record fluid-solid interaction and the interaction of the bristles with each other. Designing a prototype to empirically model this problem serves as a fundamental and critical step in understanding the fluid interaction with seals in high-pressure steam turbines and will identify brush seal modes of failure. The prototype’s ability to model steam turbine conditions and rapidly test various seal designs will facilitate better brush seal designs to be constructed and will ultimately increase the thermal efficiencies of steam turbines, aid in accommodating the increase in global energy demands, and reduce the detrimental environmental impacts of producing power. The system successfully produced and recorded brush-seal-bristle flutter while modeling high-pressure steam turbine conditions. Matching Reynolds and Euler numbers of the steam turbine stages provided the ability to scale the steam turbine to our prototype, with air as the working fluid. Brush seal breakdown was occurring in steam turbines at Reynolds numbers above 20,000. The prototype repeatedly produced brush seal flutter at Reynolds numbers above 25,000, validating the theory that brush seal breakdown is dependent predominantly on the Reynolds number.

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.

Design Philosophy and Dynamic Calculation Method for Optimized Load Rejection Characteristics of Steam Turbines

2012 ◽  
Author(s):  
Christoph Schindler ◽  
Gerta Zimmer
Keyword(s):  
Steam Turbine ◽  
Dynamic Equilibrium ◽  
Reaction Times ◽  
Operational Reliability ◽  
Steam Turbines ◽  
Electrical Grid ◽  
Counter Measures ◽  
Failure Conditions ◽  
Turbine Speed ◽  
The Impact

A load rejection disconnects the generator from the electrical grid. The resulting power excess accelerates the turbo set. Reacting to the load rejection, the turbine governor rapidly closes the steam admission valves. The remaining entrapped steam expands, thereby continuing to power the turbine. Thus the turbine speed rises till a dynamic equilibrium of accelerating and braking forces is reached. Thereafter the turbine speed decreases. If the maximally attained turbine speed remains below the trip threshold, immediate re-synchronization to the electrical grid is possible. Consequently, a forced outage of the steam turbine can be avoided and operational reliability is increased. Furthermore, functional safety requirements demand that the maximum turbine speed remains below test speed under all failure conditions. Accordingly, steam turbine design has to account for the impact of overspeed for a reliable and safe operation of the turbo set. In order to manage load rejection requirements for steam turbine operation, the design engineer applies standard rules and overspeed calculation methods. These rules limit standardized overspeed estimation by defining maximum steam volumes, valve closing times, and I&C reaction times, as well as type and number of non-return valves. A more thorough turbine overspeed investigation is necessary for several reasons, such as to evaluate this behavior under undesired failure conditions e.g. failure of non-return valves or blocking of control valves. A second justification for this investigation would be to predict changes resulting from turbine modifications — e.g. turbine upgrade or change at I&C systems. In this paper, basic and advanced overspeed calculation tools are illustrated and compared, with respect to required effort as well as accuracy of prediction. It is shown how system parameters which are most sensitive with respect to overspeed can be identified and their influence assessed. Thus, firstly it is already possible to identify and improve critical overspeed behavior during design. Secondly, the impact of particular failures can be accurately predicted, thus allowing for due implementation of appropriate counter measures. The methods, presented in this paper, were developed by the authors and their predecessors at SIEMENS AG for large steam turbo sets with a power range between 100 MW and 1500 MW.

Investigation Into a “Steam Whirl” Which Affected HP Rotors of 300 MW Steam Turbines

2007 ◽  
Author(s):  
Janusz Kubiak Sz. ◽  
Dara Childs ◽  
M. Rodri`guez ◽  
J. C. Garci´a
Keyword(s):  
Steam Turbine ◽  
The Other ◽  
Steam Turbines ◽  
Full Load ◽  
The Past ◽  
Instability Effect ◽  
Valve Opening ◽  
Rotordynamic Forces ◽  
Rotor Model ◽  
Load Conditions

In the past, several 300 MW steam turbine rotors were affected by vibrations, which appeared at bearing #1 during load conditions. At certain loads, vibrations of the #1 bearing increased considerably. Near full load the amplitude of vibration sometimes reduced to acceptable levels. Practically, the phenomena were partially cured by trim balancing of the HP rotor, readjusting the valve opening characteristics and by correction of the clearances in the sealing system. The results are briefly summarized. On the other hand, the simulation of the various parameters using rotordynamic codes was conducted to explain the phenomena analytically. In this part, the rotordynamic rotor model was constructed and the following simulations were carried out: rotor bearing instability, effect of the destabilizing steam forces on the rotor at the first row, effect of the seal rotordynamic forces and the valve opening sequence on the rotor stability. All results were analyzed to present general conclusions.

Nuclear Steam Turbine With 60 inch Last Stage Blade

2013 ◽  
Author(s):  
Motonari Haraguchi ◽  
Tateki Nakamura ◽  
Hideo Yoda ◽  
Takeshi Kudo ◽  
Shigeki Senoo
Keyword(s):  
Steam Turbine ◽  
Nuclear Power ◽  
New Technologies ◽  
The Other ◽  
Power Equipment ◽  
Steam Turbines ◽  
Candu Reactors ◽  
Last Stage ◽  
Reactor Types ◽  
And Performance

Nuclear steam turbines can be classified into two categories, one for BWR reactors where some countermeasures are taken for radiated steam and water, the other is for PWR reactors and PHWR (CANDU) reactors where steam and water are not radiated. As for Low Pressure section, there is some difference in LP rotor end structure, and LP last three stage blade components can be applied to all reactor types. The trend in nuclear power equipment is in a direction of larger capacity. In response to this trend, longer last stage blade is required if same number of casing is kept to make nuclear turbines reasonably compact. This paper addresses some of the key developments and new technologies to be employed focusing on longer Last Stage Blade (LSB) development with Continuous Cover Blades (CCB), and other enhancements in product reliability and performance.

Toughness of Cr-Mo-V Steels for Steam Turbine Rotors

1983 ◽  
Vol 105 (4) ◽  
pp. 286-294 ◽  
Author(s):  
R. Viswanathan ◽  
R. I. Jaffee
Keyword(s):  
High Pressure ◽  
Steam Turbine ◽  
Major Influence ◽  
Steam Turbines ◽  
Factors Affecting ◽  
Intermediate Pressure ◽  
Research Programs ◽  
Operation And Maintenance ◽  
Better Than ◽  
Broad Overview

Cr-Mo-V steels are used extensively as the rotor material in the High Pressure and Intermediate Pressure Sections of modern steam turbines. The toughness of these rotors has a major influence on the reliability and efficiency of the turbine and the overall economy of operation and maintenance of the plant. The metallurgical factors affecting the toughness of the rotors and the methods to improve the toughness are now understood better than ever before. This paper will present a broad overview of the materials and design aspects of the toughness of Cr-Mo-V rotors with emphasis on the salient results of recent research programs aimed at improving their toughness.

scholarly journals Steam Turbine Rotor Stress Control through Nonlinear Model Predictive Control

Energies ◽  
2021 ◽  
Vol 14 (13) ◽  
pp. 3998
Author(s):  
Stefano Dettori ◽  
Alessandro Maddaloni ◽  
Filippo Galli ◽  
Valentina Colla ◽  
Federico Bucciarelli ◽  
...  
Keyword(s):  
Control System ◽  
Model Predictive Control ◽  
Steam Turbine ◽  
Predictive Control ◽  
Nonlinear Model ◽  
Computational Cost ◽  
Soft Sensor ◽  
Nonlinear Model Predictive Control ◽  
Steam Turbines ◽  
Control Logic

The current flexibility of the energy market requires operating steam turbines that have challenging operation requirements such as variable steam conditions and higher number of startups. This article proposes an advanced control system based on the Nonlinear Model Predictive Control (NMPC) technique, which allows to speed up the start-up of steam turbines and increase the energy produced while maintaining rotor stress as a constraint variable. A soft sensor for the online calculation of rotor stress is presented together with the steam turbine control logic. Then, we present how the computational cost of the controller was contained by reducing the order of the formulation of the optimization problem, adjusting the scheduling of the optimizer routine, and tuning the parameters of the controller itself. The performance of the control system has been compared with respect to the PI Controller architecture fed by the soft sensor results and with standard pre-calculated curves. The control architecture was evaluated in a simulation exploiting actual data from a Concentrated Solar Power Plant. The NMPC technique shows an increase in performance, with respect to the custom PI control application, and encouraging results.

Bauer-Wach Exhaust Steam Turbines

1934 ◽  
Vol 127 (1) ◽  
pp. 381-406
Author(s):  
E. Crossley
Keyword(s):  
Control System ◽  
Steam Turbine ◽  
General Description ◽  
Steam Turbines ◽  
Expansion Engine ◽  
Coal Consumption ◽  
The Troubles ◽  
Hydraulic Coupling ◽  
Actual Service ◽  
And Control

In 1927–8 two cargo ships of roughly 11,000 tons displacement were built by Messrs. R. and W. Hawthorn, Leslie and Company for the Booth Steamship Company of Liverpool. Originally of identical design, the plans of S.S. Boniface were altered during construction to include a Bauer-Wach exhaust steam turbine, whilst S.S. Basil was built as originally designed with a triple-expansion engine only. Builders' trials on S.S. Boniface proved the turbine to give a reduction in coal consumption of 24·5 per cent. The paper adds to the facts already known about this type of installation some information regarding reliability and economy in actual service. Following a general description of the propelling machinery and auxiliaries of the two ships, and a more detailed description of the exhaust steam turbine, gearing, hydraulic coupling, and control system of S.S. Boniface, notes are made regarding the general running and the troubles experienced with the extra equipment. Particulars of two trials at sea under normal conditions on S.S. Boniface are given, and finally, a coal consumption comparison on a yearly basis between the two ships is shown to give a saving of 15·9 per cent in favour of S.S. Boniface at the age of four years.

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