scholarly journals Unsteady Analyses of a Control Valve due to Fluid-Structure Coupling

2013 ◽  
Vol 2013 ◽  
pp. 1-7 ◽  
Author(s):  
Yudong Xie ◽  
Yong Wang ◽  
Yanjun Liu ◽  
Fang Cao ◽  
Yongcheng Pan
Keyword(s):  
Power Plants ◽  
Natural Frequencies ◽  
Oscillation Amplitude ◽  
Control Valve ◽  
Combined Cycle ◽  
Coupling Mechanism ◽  
Mixed Gas ◽  
Fluid Structure ◽  
Valve Opening ◽  
Low Order

Control valves play important roles in the control of the mixed-gas pressure in the combined cycle power plants (CCPP). In order to clarify the influence of coupling between the structure and the fluid system at the control valve, the coupling mechanism was presented, and the numerical investigations were carried out. At the same operating condition in which the pressure oscillation amplitude is greater when considering the coupling, the low-order natural frequencies of the plug assembly of the valve decrease obviously when considering the fluid-structure coupling action. The low-order natural frequencies at 25% valve opening, 50% valve opening, and 75% valve opening are reduced by 11.1%, 7.0%, and 3.8%, respectively. The results help understand the processes that occur in the valve flow path leading to the pressure control instability observed in the control valve in the CCPP.

Prediction of Gas Turbine Trip Due to Electro Hydraulic Control Valve System Failures

2010 ◽  
Author(s):  
Y. B. Ravi ◽  
Achalesh Pandey ◽  
Vinay Jammu
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Control Valve ◽  
Combined Cycle ◽  
Hydraulic Control ◽  
Current Application ◽  
System Failures ◽  
Thermal Transients ◽  
Valve System

Gas turbines are the main power producing components in combined cycle and simple cycle power plants. A gas turbine trip is a rapid uncontrolled shutdown of the turbine that is initiated by the turbine controller to protect it from failures. The turbine loses significant amount of life due to strong thermal transients during a trip and the utility company loses revenue because of lost power generation. Therefore, prediction of trips has significant financial impact. This paper presents a method to predict gas turbine trips due to electro hydraulic control valve system failures. This paper also provides methods to detect gas control valve system failures in their incipient phase and methods to identify various failure signatures for diagnostics. The methodology presented here could be extended beyond the current application to other causes of trips in the gas turbine, thereby impacting availability and reliability of the turbine.

Effect of Internal Leakage on an Electro-Hydraulic Servo-Driven Control Valve Performance

2011 ◽  
Vol 99-100 ◽  
pp. 901-905 ◽  
Author(s):  
Yu Dong Xie ◽  
Yan Jun Liu ◽  
Yong Wang
Keyword(s):  
Control Valve ◽  
Mathematic Model ◽  
Combined Cycle ◽  
Mixed Gas ◽  
Control Effect ◽  
Dead Band ◽  
Hydraulic Servo ◽  
The Dead ◽  
Valve Control ◽  
Control Accuracy

The principle of an electro-hydraulic servo-driven control valve used to regulate mixed-gas pressure in combined cycle power plant is introduced. The mathematic model for describing the dead-band characteristics of the electro-hydraulic servo-driven control valve is built. The effect of driving system leakage of the control valve on the performances of the control valve is analyzed. The results show that the dead band of the electro-hydraulic servo-driven control valve increases with the rise of the system leakage, the leakage affects the response rapidity and the control accuracy of the control valve, and the valve control effect on the pressure pulsation of the mixed gas decreases with the increase of the system leakage.

Investigation of Different Operation Strategies to Provide Balance Energy With an Industrial Combined Heat and Power Plant Using Dynamic Simulation

2016 ◽  
Vol 139 (1) ◽  
Author(s):  
Steffen Kahlert ◽  
Hartmut Spliethoff
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Dynamic Simulation ◽  
Process Model ◽  
Power Plants ◽  
Control Valve ◽  
Combined Heat And Power ◽  
Combined Cycle ◽  
Water Steam ◽  
Load Change

Intermittency of renewable electricity generation poses a challenge to thermal power plants. While power plants in the public sector see a decrease in operating hours, the utilization of industrial power plants is mostly unaffected because process steam has to be provided. This study investigates to what extent the load of a combined heat and power (CHP) plant can be reduced while maintaining a reliable process steam supply. A dynamic process model of an industrial combined CHP plant is developed and validated with operational data. The model contains a gas turbine (GT), a single pressure heat recovery system generator (HRSG) with supplementary firing and an extraction condensing steam turbine. Technical limitations of the gas turbine, the supplementary firing, and the steam turbine constrain the load range of the plant. In consideration of these constraints, different operation strategies are performed at variable loads using dynamic simulation. A simulation study shows feasible load changes in 5 min for provision of secondary control reserve (SCR). The load change capability of the combined cycle plant under consideration is mainly restricted by the water–steam cycle. It is shown that both the low pressure control valve (LPCV) of the extraction steam turbine and the high pressure bypass control valve are suitable to ensure the process steam supply during the load change. The controllability of the steam turbine load and the process stability are sufficient as long as the supplementary is not reaching the limits of the operating range.

Effect of Inlet Steam Temperature on the HP Section Efficiency of a Steam Turbine

2015 ◽  
Author(s):  
Yiping Fu ◽  
Thomas Winterberger
Keyword(s):  
Steam Turbine ◽  
Power Plants ◽  
Pressure Ratio ◽  
Control Valve ◽  
Combined Cycle ◽  
Steam Turbines ◽  
Steam Temperature ◽  
Load Range ◽  
Lp Turbine ◽  
The Relationship

Steam turbines for modern fossil and combined cycle power plants typically utilize a reheat cycle with High Pressure (HP), Intermediate Pressure (IP), and Low Pressure (LP) turbine sections. For an HP turbine section operating entirely in the superheat region, section efficiency can be calculated based on pressure and temperature measurements at the inlet and exhaust. For this case HP section efficiency is normally assumed to be a constant value over a load range if inlet control valve position and section pressure ratio remain constant. It has been observed that changes in inlet steam temperature impact HP section efficiency. K.C. Cotton stated that ‘the effect of throttle temperature on HP turbine efficiency is significant’ in his book ‘Evaluating and Improving Steam Turbine Performance’ (2nd Edition, 1998). The information and conclusions provided by K.C. Cotton are based on test results for large fossil units calculated with 1967 ASME steam tables. Since the time of Mr. Cotton’s observations, turbine configurations have evolved, more accurate 1997 ASME steam tables have been released, and our ability to quickly analyze large quantities of data has greatly increased. This paper studies the relationship between inlet steam temperature and HP section efficiency based on both 1967 and 1997 ASME steam tables and recent test data, which is analyzed computationally to reveal patterns and trends. With the efficiencies of various inlet pressure class HP section turbines being calculated with both 1967 and 1997 ASME steam tables, a comparison reveals different characteristics in the relationship between inlet steam temperature and HP section efficiency. Recommendations are made on how the results may be used to improve accuracy when testing and trending HP section performance.

Startup and Shutdown Steam Generator Separator Piping Forces for a Coal-Fired Supercritical Power Plant

2012 ◽  
Author(s):  
Rajgopal Vijaykumar ◽  
Julie M. Jarvis ◽  
Allen T. Vieira ◽  
James Humphrey ◽  
Dong Zheng
Keyword(s):  
Control System ◽  
Steam Generator ◽  
Power Plants ◽  
Cold Water ◽  
Control Valve ◽  
Operating Conditions ◽  
Operating Characteristics ◽  
Two Phase ◽  
Wide Range ◽  
Valve Opening

Coal-fired supercritical power plants have steam generator liquid/vapor separator systems used during transition to/from “drum” mode and “once-through” mode, which undergo flow transients, involving control systems and valve openings, during startup and shutdown. These transients result in fluid acceleration which can produce significant reaction loads on piping systems (20 kips or higher). The evaluation of these loads is used to design piping supports and to assess possible control system and valving modifications. The computation of these transient loadings is challenging because the conditions in steam generator separator systems range from supercritical to subcritical, two phase, cold water or steam conditions occurring over a wide range of pressures and valve operating characteristics. A transient analysis of a typical separator-condensate line is performed using computer codes RELAP5/MOD3.2 and R5FORCE for the hydrodynamic forcetime history. A range of hydraulic loads associated with a range of operating conditions is provided in this paper using different boundary conditions for separator tank pressure, initial temperature of water in pipe lines, and control valve opening/closing times. These sensitivity runs show the benefit of plant control system changes to prevent the control valves opening above 1400 psia, increasing the control valve opening time to over one second, and the effects of keeping the separator-condensate line hot.

Investigation of Different Operation Strategies to Provide Balance Energy With an Industrial CHP Plant Using Dynamic Simulation

2016 ◽  
Author(s):  
Steffen Kahlert ◽  
Hartmut Spliethoff
Keyword(s):  
Steam Turbine ◽  
Gas Turbine ◽  
Dynamic Simulation ◽  
Process Model ◽  
Power Plants ◽  
Thermal Power ◽  
Control Valve ◽  
Combined Cycle ◽  
Water Steam ◽  
Load Change

Intermittency of renewable electricity generation poses a challenge to thermal power plants. While power plants in the public sector see a decrease in operating hours, the utilization of industrial power plants is mostly unaffected because process steam has to be provided. This study investigates to what extent the load of a CHP plant can be reduced while maintaining a reliable process steam supply. A dynamic process model of an industrial combined CHP plant is developed and validated with operational data. The model contains a gas turbine, a single pressure HRSG with supplementary firing and an extraction condensing steam turbine. Technical limitations of the gas turbine, the supplementary firing and the steam turbine constrain the load range of the plant. In consideration of these constraints, different operation strategies are performed at variable loads using dynamic simulation. A simulation study shows feasible load changes in 5 min for provision of secondary control reserve. The load change capability of the combined cycle plant under consideration is mainly restricted by the water-steam cycle. It is shown that both the low pressure control valve of the extraction steam turbine and the high pressure bypass control valve are suitable to ensure the process steam supply during the load change. The controllability of the steam turbine load and the process stability are sufficient as long as the supplementary is not reaching the limits of the operating range.

Prediction Model of Control Valve Characteristics

2012 ◽  
Vol 605-607 ◽  
pp. 1345-1349
Author(s):  
Yu Dong Xie ◽  
Yan Jun Liu ◽  
Yong Wang
Keyword(s):  
Fluid Flow ◽  
Dynamic Performance ◽  
Control Valve ◽  
Flow Regulation ◽  
Combined Cycle ◽  
Quality And Safety ◽  
Hydraulic Control ◽  
Mixed Gas ◽  
Mathematical Simulations ◽  
Process Output

Control valves are generally present whenever fluid flow regulation is required. The control valve reliability is critical to the control quality and safety of a plant. An improved dynamic and static valve behaviour would have a major impact on the process output. In order to assess the dynamic performance of the control valve, a computer model of an electro-hydraulic control valve is developed. And the control valve characteristics are investigated through the use of mathematical simulations of the control valve dynamic performance. The results show that the electro-hydraulic driven control valve, which is developed to regulate the mixed-gas pressure in combined cycle power plant, can meet the challenge of the gas turbine.

Current and Future Technologies for Natural Gas Combined Cycle (NGCC) Power Plants

2013 ◽  
Author(s):  
Norma J. Kuehn ◽  
Kajal Mukherjee ◽  
Paul Phiambolis ◽  
Lora L. Pinkerton ◽  
Elsy Varghese ◽  
...  
Keyword(s):  
Natural Gas ◽  
Power Plants ◽  
Combined Cycle ◽  
Natural Gas Combined Cycle ◽  
Future Technologies

Optimization of fog inlet air cooling system for combined cycle power plants using genetic algorithm

2015 ◽  
Vol 76 ◽  
pp. 449-461 ◽  
Author(s):  
Mehdi A. Ehyaei ◽  
Mojtaba Tahani ◽  
Pouria Ahmadi ◽  
Mohammad Esfandiari
Keyword(s):  
Genetic Algorithm ◽  
Power Plants ◽  
Cooling System ◽  
Combined Cycle ◽  
Air Cooling ◽  
Air Cooling System
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