Life Management System for Hot-Gas-Path Components of Gas Turbines

1999 ◽  
Author(s):  
Yasushi Hayasaka ◽  
Nobuhiro Isobe ◽  
Shigeo Sakurai ◽  
Kazuhiko Kumata
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Management System ◽  
Residual Life ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Life Assessment ◽  
Hot Gas ◽  
Life Management ◽  
Residual Life Assessment

Recently the number of gas-turbine-powered combined-cycle plants has been increasing because of their efficiency and environmental compatibility. Gas turbine operating conditions are severe, especially for hot-gas-path components. To improve the reliability of such components and to extend their life, we have developed a life management system based on a residual-life-assessment method. The system makes possible integrated residual-life-assessment based on numerical analyses, material destructive-tests, nondestructive inspections, statistical analyses of field machine data, and the use of a database. To develop the system, the primary damage mechanism for each component is clarified and material degradation is evaluated. For nozzles, the system describes a method of predicting the maximum surface crack growth. The validity of the methods is verified by assessment of the inspection data. This paper also describes optimization of operating cost and RAM (reliability, availability and maintainability).

Gas Turbine Exhaust Expansion Joints, Diverter and Damper Designs for the New Generation of Higher Temperature, High Efficiency Gas Turbines

1989 ◽  
Author(s):  
Lothar Bachmann ◽  
W. Fred Koch
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Combined Cycle ◽  
Operating Conditions ◽  
High Mass ◽  
Expansion Joints ◽  
Gas Turbine Exhaust ◽  
New Generation ◽  
Turbine Exhaust

The purpose of this paper is to update the industry on the evolutionary steps that have been taken to address higher requirements imposed on the new generation combined cycle gas turbine exhaust ducting expansion joints, diverter and damper systems. Since the more challenging applications are in the larger systems, we shall concentrate on sizes from nine (9) square meters up to forty (40) square meters in ducting cross sections. (Reference: General Electric Frame 5 through Frame 9 sizes.) Severe problems encountered in gas turbine applications for the subject equipment are mostly traceable to stress buckling caused by differential expansion of components, improper insulation, unsuitable or incompatible mechanical design of features, components or materials, or poor workmanship. Conventional power plant expansion joints or dampers are designed for entirely different operating conditions and should not be applied in gas turbine applications. The sharp transients during gas turbine start-up as well as the very high temperature and high mass-flow operation conditions require specific designs for gas turbine application.

Incremental Fuel Cost Prediction for a Gas Turbine Combined Cycle Utility

1989 ◽  
Author(s):  
D. Little ◽  
H. Nikkels ◽  
P. Smithson
Keyword(s):  
Gas Turbine ◽  
Fuel Consumption ◽  
Gas Turbines ◽  
Operating Experience ◽  
Load Level ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Fuel Cost ◽  
Ambient Conditions ◽  
Cost Prediction

For a medium sized (300 MW) utility producing electricity from a 130 MW combined cycle, and supplemental 15 MW to 77 MW capacity simple cycle gas turbines, the incremental fuel costs accompanying changes in generating capacity vary considerably with unit, health, load level, and ambient. To enable incremental power to be sold to neighbouring utilities on an incremental fuel cost basis, accurate models of all gas turbines and the combined cycle were developed which would allow a realistic calculation of fuel consumption under all operating conditions. The fuel cost prediction program is in two parts; in the first part, gas turbine health is diagnosed from measured parameters; in the second part, fuel consumption is calculated from compressor and turbine health, ambient conditions and power levels. The paper describes the program philosophy, development, and initial operating experience.

Damage Analysis of Gas Turbine Vanes Using a Thermal Fluid Dynamic and Mechanical Approach

2004 ◽  
Author(s):  
Enrico Marchegiano ◽  
Giancarlo Benelli ◽  
Paolo Gheri ◽  
Donato Aquaro
Keyword(s):  
High Temperature ◽  
Gas Turbine ◽  
Residual Life ◽  
Crack Nucleation ◽  
Fluid Dynamic ◽  
Load Cycle ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Turbine Vanes ◽  
Cycle Systems

Gas turbine combined–cycle systems work with high inlet temperatures, requiring the use of components made of advanced high temperature resistant materials and coatings. These components must be controlled to avoid serious damage to the plants. The durability of these materials and coatings is of great concern to equipment users. This paper deals with a procedure based on thermal fluid dynamic and mechanical integrated analyses of high temperature loaded components. The methodology is applied to uncooled last stator stages vanes of an industrial 165 Mw gas turbine. Several cracks were revealed on these vanes during periodical inspection and mechanical and metallographic investigations were performed. These analyses were used to identify the critical areas of the vanes, from which the component residual life depends on. The procedure was applied to study the damage undergone by gas turbine vanes to discover the causes of crack nucleation and the nucleation mechanism connected to load histories. It has a diagnostic scope, not a predictive one, but it can be considered as the first step of a residual life evaluation and, consequently, of a load cycle optimization: by modifying the future load histories, it could be possible evaluate the best operating conditions to extend component life. The numerical results of these analyses were compared with the damage to vane rows determined during periodical inspections. A good agreement between the analyses results and the inspection data was obtained in terms of critical points and crack locations. The implemented methodology seems to be a powerful tool for increasing the reliability of critical components of gas turbine combined–cycle systems.

Numerical and Experimental Investigation of Secondary Flows and Influence of Air System Design on Heavy-Duty Gas Turbine Performance

2012 ◽  
Author(s):  
Luca Bozzi ◽  
Enrico D’angelo
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Engine Performance ◽  
Combined Cycle ◽  
Secondary Flows ◽  
Operating Conditions ◽  
Heavy Duty ◽  
Turbine Performance ◽  
Air System ◽  
Secondary Air

High turn-down operating of heavy-duty gas turbines in modern Combined Cycle Plants requires a highly efficient secondary air system to ensure the proper supply of cooling and sealing air. Thus, accurate performance prediction of secondary flows in the complete range of operating conditions is crucial. The paper gives an overview of the secondary air system of Ansaldo F-class AEx4.3A gas turbines. Focus of the work is a procedure to calculate the cooling flows, which allows investigating both the interaction between cooled rows and additional secondary flows (sealing and leakage air) and the influence on gas turbine performance. The procedure is based on a fluid-network solver modelling the engine secondary air system. Parametric curves implemented into the network model give the consumption of cooling air of blades and vanes. Performances of blade cooling systems based on different cooling technology are presented. Variations of secondary air flows in function of load and/or ambient conditions are discussed and justified. The effect of secondary air reduction is investigated in details showing the relationship between the position, along the gas path, of the upgrade and the increasing of engine performance. In particular, a section of the paper describes the application of a consistent and straightforward technique, based on an exergy analysis, to estimate the effect of major modifications to the air system on overall engine performance. A set of models for the different factors of cooling loss is presented and sample calculations are used to illustrate the splitting and magnitude of losses. Field data, referred to AE64.3A gas turbine, are used to calibrate the correlation method and to enhance the structure of the lumped-parameters network models.

Investigations of a Syngas-Fired Gas Turbine Model Combustor by Planar Laser Techniques

2006 ◽  
Author(s):  
Michael Tsurikov ◽  
Wolfgang Meier ◽  
Klaus-Peter Geigle
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Combined Cycle ◽  
Operating Conditions ◽  
Integrated Gasification Combined Cycle ◽  
Combustion Behavior ◽  
Air Temperatures ◽  
Planar Laser ◽  
Integrated Gasification

In order to investigate the combustion behavior of gas turbine flames fired with low-caloric syngases, a model combustor with good optical access for confined, non-premixed swirl flames was developed. The measuring techniques applied were particle image velocimetry, OH* chemiluminescence detection and laser-induced fluorescence of OH. Two different fuel compositions of H2, CO, N2 and CH4, with similar laminar burning velocities, were chosen. Their combustion behavior was studied at two different pressures, two thermal loads and two combustion air temperatures. The overall lean flames (equivalence ratio 0.5) burned very stably and their shapes and combustion behavior were hardly influenced by the fuel composition or by the different operating conditions. The experimental results constitute a data-base that will be used for the validation of numerical combustion models and form a part of a co-operative EC project aiming at the development of highly efficient gas turbines for IGCC (Integrated Gasification Combined Cycle) power plants.

Gas Turbine Life Extension: A 655 MW Combined Cycle Power Plant User’s Experience

2003 ◽  
Author(s):  
Hemant Gajjar ◽  
Sunil Jain ◽  
Arpesh Modi
Keyword(s):  
Risk Assessment ◽  
Power Plant ◽  
Gas Turbine ◽  
Combined Cycle ◽  
Life Assessment ◽  
Life Extension ◽  
Maintenance Cost ◽  
Power Station ◽  
Combined Cycle Power Plant ◽  
Hot Gas

Gujarat Paguthan Energy Corporation Pvt. Ltd. (GPEC) is operating a Combined Cycle Power Plant, located near Paguthan in the state of Gujarat, India. It is a dual fuel 655MW combined cycle power station consisting of three Heavy Duty Industrial Gas Turbines coupled with three Heat Recovery Steam Generators and one Steam Turbine. In a combined cycle plant, Gas Turbine is the single most critical piece of equipment & costliest to maintain. Maintenance cost of GT can be as high as 85% of the total maintenance cost of a combined cycle power station. It therefore becomes important for a plant operator not only to optimise the maintenance cost but also to look for possible extension in the life of the engine. OEM inherently builds in a factor of safety and coupled with the site operating conditions it is a question of how much more can be squeezed out of a component & the engine as a whole. GPEC’s experience of getting life assessment done on 6 numbers of turbine blades and also making an experience based risk assessment of various hot gas path and critical components is discussed in this paper. The life assessment, for a user, has to basically answer two questions: 1) Can the interval between outages of GT be extended? in other words — How long can the GT be run before taking a planned shutdown (Combustion Inspection or Hot Gas Path Inspection or Major Inspection)? 2) Can the component be refurbished and reused? in other words — How long can a component be used before discarding? Decision for life extension is taken on the basis of the design criteria & OEM’s recommendation, operating experience of self & other users and, results of life assessment testing specially of hot gas path components. A risk assessment table is generated which gives a picture of the possibility of engine life extension and in particular the possibility of extension in running hours between outages. GPEC’s experience, from both technical and commercial point of view, with regard to extending running hours beyond standard recommendation & analysing right refurbishment requirements for hot gas path components to further extend the running hours, is put up in this paper.

Residual Life Assessment of a Critical Component of a Gas Turbine: Achievements and Challenges

2014 ◽  
Author(s):  
Wieslaw Beres ◽  
Zhong Zhang ◽  
David Dudzinski ◽  
W. R. Chen ◽  
X. J. Wu
Keyword(s):  
Crack Propagation ◽  
Gas Turbine ◽  
Mixed Mode ◽  
Residual Life ◽  
Crack Nucleation ◽  
Three Dimensional ◽  
Life Assessment ◽  
Mode Interaction ◽  
Turbine Engine ◽  
Residual Life Assessment

The residual life assessment of a turbine spacer from a gas turbine engine is presented. The spacer has been identified as one of the safety critical components of the engine, therefore the useful life of this component significantly affects economic operation of the fleet. Numerical analyses of fatigue crack propagation at one critical location of the spacer were performed using both three dimensional (3D) finite element based method and the weight function method. These results combined with the material data allowed for basic assessment of the damage tolerance of this component. Experimental validation of the spacer life was performed in a spin rig facility. During this validation, two sets of spacers were tested and the number of cycles to appearance of a detectable crack was recorded. Moreover, a fractographic study was conducted on the fracture surfaces of two spin rig tested spacers using scanning electronic microscopy techniques. It was found that crack nucleation occurred at multiple sites and crack propagation occurred by a mixed mode of striation formation and faceted fracture. Therefore it was concluded that the mixed mode interaction should be considered in predicting the fatigue life of the spacer. Finally, the paper describes the challenges and pitfalls encountered during preparation and execution of the analyses and tests, including availability of engine and operational data and also uncertainties in interpretation of the results.

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