On-Line Health Monitoring Research on T-Joint of Main Steam Piping

2013 ◽  
Vol 330 ◽  
pp. 549-552 ◽  
Author(s):  
J.H. Jia ◽  
H.C. Zhang ◽  
X.Y. Hu ◽  
L.P. Cai ◽  
S.T. Tu
Keyword(s):  
High Temperature ◽  
Power Plant ◽  
Residual Life ◽  
Thermal Power ◽  
Creep Damage ◽  
Piping System ◽  
Main Challenge ◽  
On Line ◽  
Main Steam ◽  
Creep Monitoring

The main challenge of long-time creep monitoring on site is a reliable sensor. In this paper, a sensing device is developed specifically for high temperature creep monitoring. And it is applied to on-line monitor the strain of material on T-joint of main steam piping. Its reliability is verified theoretically using the finite element method and experimentally by high temperature on site test. The creep damage of the T joint is evaluated basing on the creep rate sensed by the sensing device. And the residual life is predicted for the piping system using the Monkman-Grant equation. This system is useful for safety assessment procedures in thermal power plant, nuclear power plant and petrochemical industries.

On-Line Monitoring System for Main Steam Piping of Power Plants

2009 ◽  
Author(s):  
Ning Wang ◽  
Zhengdong Wang ◽  
Yingqi Chen
Keyword(s):  
Power Plant ◽  
Monitoring System ◽  
Remote Monitoring ◽  
Power Plants ◽  
Residual Life ◽  
Thermal Power ◽  
Creep Damage ◽  
Piping System ◽  
On Line ◽  
Main Steam

An on-line life prediction system is developed for remote monitoring of material aging in a main steam piping system. The stress analysis of piping system is performed by using the finite element method. A sensor network is established in the monitoring system. The creep damage is evaluated from strain gages and a relationship is given based on a database between the damage and residual life. Web technologies are used for remote monitoring to predict the residual life for every part of the piping system. This system is useful for safety assessment procedures in thermal power plant, nuclear power plant and petrochemical industries.

Life Prediction of the Tapered Pipe With High Temperature and High Pressure by Finite Element Methods

2007 ◽  
Author(s):  
Juntao Bao ◽  
Jianming Gong ◽  
Shantung Tu ◽  
Yuesheng Li ◽  
Yanfei Qiu
Keyword(s):  
Finite Element ◽  
High Pressure ◽  
High Temperature ◽  
Internal Pressure ◽  
Creep Damage ◽  
Piping System ◽  
Bending Moments ◽  
Finite Element Program ◽  
Element Program ◽  
Main Steam

Tapered pipe used in the main steam pipelines, which operated at high temperature and high pressure, including concentric tapered pipe and eccentric tapered pipe, they are sources of weakness in the piping system serviced in the power stations and the chemical plants, and creep is the significant reason that caused their failure. Creep damage analyses are carried out for these two kinds of tapered pipes by introducing user subroutine based on the modified Karchanov-Rabotnov constitutive equations into finite element program ABAQUS, then the effects of bending moments and internal pressure to the serviced life of the components are investigated by comparing four group of calculated results under different loads, the results indicated that eccentric tapered pipe is more inclinable to broken than concentric tapered pipe under the same conditions, so it is not recommended to use the eccentric tapered pipe in the piping system. The bending moments will accelerate the components’ failure, so it is necessary to take some advantages to reduce the bending moments near the tapered pipe, on the other hand, the life of the tapered pipe will decrease quickly with the internal pressure increasing, so the control of the operated pressure is important to ensure the serviced life of the pipelines.

Residual life prediction of service exposed main steam pipe of boilers in a thermal power plant

2000 ◽  
Vol 7 (5) ◽  
pp. 359-376 ◽  
Author(s):  
A.K. Ray ◽  
Y.N. Tiwari ◽  
R.K. Sinha ◽  
S. Chaudhuri ◽  
R. Singh
Keyword(s):  
Power Plant ◽  
Thermal Power Plant ◽  
Life Prediction ◽  
Residual Life ◽  
Thermal Power ◽  
Steam Pipe ◽  
Residual Life Prediction ◽  
Main Steam

Time History Steam Hammer Analysis for Critical Hot Lines in Thermal Power Plants

2014 ◽  
Author(s):  
Ahmed H. Bayoumy ◽  
Anestis Papadopoulos
Keyword(s):  
Power Plant ◽  
Dynamic Response ◽  
Power Plants ◽  
Thermal Power ◽  
Time History ◽  
Piping System ◽  
Pressure Waves ◽  
Root Cause ◽  
Pipe Line ◽  
Main Steam

Pressure surges and fluid transients, such as steam and water hammer, are events that can occur unexpectedly in operating power plants causing significant damages. When these transients occur the power plant can be out of service for long time, until the root cause is found and the appropriate solution is implemented. In searching for root cause of transients, engineers must investigate in depth the fluid conditions in the pipe line and the mechanism that initiated the transients. The steam hammer normally occurs when one or more valves suddenly close or open. In a power plant, the steam hammer could be an inevitable phenomenon during turbine trip, since valves (e.g., main steam valves) must be closed very quickly to protect the turbine from further damage. When a valve suddenly stops at a very short time, the flow pressure builds up at the valve, starting to create pressure waves along the pipe runs which travel between elbows. Furthermore, these pressure waves may cause large dynamic response on the pipeline and large loads on the pipe restraints. The response and vibrations on the pipeline depend on the pressure waves amplitudes, frequencies, the natural frequencies and the dynamic characteristics of the pipeline itself. The piping flexibility or rigidity of the pipe line, determine how the pipes will respond to these waves and the magnitude of loads on the pipe supports. Consequently, the design of the piping system must consider the pipeline response to the steam hammer loads. In this paper, a design and analysis method is proposed to analyze the steam hammer in the critical hot lines due to the turbine trip using both PIPENET transient module and CAESAR II programs. The method offered in this paper aims to assist the design engineer in the power plant industry to perform dynamic analysis of the piping system considering the dynamic response of the system using the PIPENET and CAESAR II programs. Furthermore, the dynamic approach is validated with a static method by considering the appropriate dynamic load and transmissibility factors. A case study is analyzed for a typical hot reheat line in a power plant and the results of the transient analysis are validated using the theoretical static approach.

Ranking of Creep Damage in Main Steam Piping System Girth Welds Considering Multiaxial Stress Ranges

2016 ◽  
Vol 138 (4) ◽  
Author(s):  
Marvin J. Cohn ◽  
Fatma G. Faham ◽  
Dipak Patel
Keyword(s):  
Creep Damage ◽  
High Energy ◽  
Sustained Load ◽  
Piping System ◽  
Multiaxial Stress ◽  
Analysis Model ◽  
Principal Stresses ◽  
Piping Systems ◽  
Girth Welds ◽  
Main Steam

A high-energy piping (HEP) asset integrity management program is important for the safety of plant personnel and reliability of the fossil plant generating unit. HEP weldment failures have resulted in serious injuries, fatalities, extensive damage of components, and significant lost generation. The main steam (MS) piping system is one of the most critical HEP systems. Creep damage assessment in MS piping systems should include the evaluation of multiaxial stresses associated with field conditions and significant anomalies, such as malfunctioning supports and significant displacement interferences. This paper presents empirical data illustrating that the most critical girth welds of MS piping systems have creep failures which can be successfully ranked by a multiaxial stress parameter, such as maximum principal stress. Inelastic (redistributed) stresses at the piping outside diameter (OD) surface were evaluated for the base metal of three MS piping systems at the piping analysis model nodes. The range of piping system stresses at the piping nodes for each piping system was determined for the redistributed creep stress condition. The range of piping stresses was subsequently included on a Larson–Miller parameter (LMP) plot for the grade P22 material, revealing the few critical (lead-the-fleet) girth welds selected for nondestructive examination (NDE). In the three MS piping systems, the stress ranges varied from 55% to 80%, with only a few locations at stresses beyond the 65 percentile of the range. By including evaluations of significant field anomalies and the redistributed multiaxial stresses on the outside surface, it was shown that there is a good correlation of the ranked redistributed multiaxial stresses to the observed creep damage. This process also revealed that a large number of MS piping girth welds have insufficient applied stresses to develop substantial creep damage within the expected unit lifetime (assuming no major fabrication defects). This study also provided a comparison of the results of a conventional American Society of Mechanical Engineers (ASME) B31.1 Code as-designed sustained stress analysis versus the redistributed maximum principal stresses in the as-found (current) condition for a complete set of MS piping system nodes. The evaluations of redistributed maximum principal stresses in the as-found condition were useful in selecting high priority ranked girth weldment creep damage locations. The evaluations of B31.1 Code as-designed sustained load stresses were not useful in selecting high priority creep damage locations.

Review of Control Strategies Employing Neural Network for Main Steam Temperature Control in Thermal Power Plant

2014 ◽  
Vol 66 (2) ◽  
Author(s):  
N. A. Mazalan ◽  
A. A. Malek ◽  
Mazlan A. Wahid ◽  
M. Mailah
Keyword(s):  
Neural Network ◽  
Power Plant ◽  
Temperature Control ◽  
Pid Control ◽  
Thermal Power Plant ◽  
Thermal Power ◽  
Heat Rate ◽  
Steam Temperature ◽  
Multiple Variables ◽  
Main Steam

Main steam temperature control in thermal power plant has been a popular research subject for the past 10 years. The complexity of main steam temperature behavior which depends on multiple variables makes it one of the most challenging variables to control in thermal power plant. Furthermore, the successful control of main steam temperature ensures stable plant operation. Several studies found that excessive main steam temperature resulted overheating of boiler tubes and low main steam temperature reduce the plant heat rate and causes disturbance in other parameters. Most of the studies agrees that main steam temperature should be controlled within ±5 Deg C. Major factors that influenced the main steam temperature are load demand, main steam flow and combustion air flow. Most of the proposed solution embedded to the existing cascade PID control in order not to disturb the plant control too much. Neural network controls remains to be one of the most popular algorithm used to control main steam temperature to replace ever reliable but not so intelligent conventional PID control. Self-learning nature of neural network mean the load on the control engineer re-tuning work will be reduced. However the challenges remain for the researchers to prove that the algorithm can be practically implemented in industrial boiler control.

THE LIFE ASSESSMENT OF STEAM TURBINE ROTORS FOR FOSSIL POWER PLANTS

2006 ◽  
Vol 20 (25n27) ◽  
pp. 4371-4376
Author(s):  
SUNGHO CHANG ◽  
GEEWOOK SONG ◽  
BUMSHIN KIM ◽  
JUNGSEB HYUN ◽  
JEONGSOO HA
Keyword(s):  
Power Plant ◽  
Steam Turbine ◽  
Rotational Speed ◽  
Power Plants ◽  
Thermal Power ◽  
Creep Damage ◽  
Life Assessment ◽  
Life Extension ◽  
Start Up ◽  
Operational Life

The operational mode of thermal power plants has been changed from base load to duty cycle. From the changeover, fossil power plants cannot avoid frequent thermal transient states, for example, start up and stop, which results in thermal fatigue damage at the heavy section components. The rotor is the highest capital cost component in a steam turbine and requires long outage for replacing with a new one. For an optimized power plant operational life, inspection management of the rotor is necessary. It is known in general that the start-up and shutdown operations greatly affect the steam turbine life. The start-up operational condition is especially severe because of the rapid temperature and rotational speed increase, which causes damage and reduction of life of the main components life of the steam turbine. The start-up stress of a rotor which is directly related to life is composed of thermal and rotational stresses. The thermal stress is due to the variation of steam flow temperature and rotational stress is due to the rotational speed of the turbine. In this paper, the analysis method for the start-up stress of a rotor is proposed, which considers simultaneously temperature and rotational speed transition, and includes a case study regarding a 500MW fossil power plant steam turbine rotor. Also, the method of quantitative damage estimation for fatigue-creep damage to operational conditions, is described. The method can be applied to find weak points for fatigue-creep damage. Using the method, total life consumption can be obtained, and can be also be used for determining future operational modes and life extension of old fossil power units.

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