95-GT-421 BLADING VIBRATION AND FAILURES IN GAS TURBINES PART D: CASE STUDIES

ABSTRACT The investigation of gas turbine blade failures requires an interdisciplinary approach calling for expertise in gas turbine design, operation and metallurgy. The object of this paper is to show, in the context of blading problems, the interrelationship between design, operation, maintenance, and the operational envelope. This paper presents case studies dealing with a variety of failure modes. The treatment focuses on practical troubleshooting of blading problems augmented, in some cases, by the use of analytical tools

Case Studies In Turbomachinery Operation And Maintenance Using Condition Monitoring.

LecturePg. 101-112With exceedingly high downtime costs and the need for efficient operation of turbo machinery, integrated condition monitoring, wherein a number of health parameters are analyzed, is becoming increasingly popular in process plants and in utilities. Most operational problems can be diagnosed by developing a correlation among several key operating parameters. A wide range of condition monitoring approaches are available and this paper shows how several approaches can be used in conjunction with one another to solve operational problems. Several case studies pertaining to gas and steam turbines and compressors are presented. A matrix of condition monitoring techniques is provided and case studies are presented. Finally, future trends in the area of condition monitoring are presented

Gas Turbine Blade Failures - Causes, Avoidance, And Troubleshooting.

Tutorialpg. 129-180With blading problems accounting for as many as 42 percent of the failures in gas turbines (Allianz, 1 978) and with its severe effect on plant availability, there is a pressing need for a unified treatment of the causes, failure modes, and troubleshooting to assist plant engineers in tackling blade failure problems. This paper provides a comprehensive practical treatment of the subject, taking into account the complex nature of blading problems, influence of the operating environment, design factors, and maintenance practices. Blade failure modes such as fatigue, environmental attack, creep, erosion, and embrittlement are addressed along with a synopsis of design tools to review blade reliability. Peripheral issues affecting blade integrity such as fuel and blade quality control are addressed. A blade failure troubleshooting chart is furnished to assist users in diagnosing common failure modes. The object of this paper is to show, in the context of blading problems, the interrelationship between design, operation, maintenance, and the operational envelope. Several case studies are presented dealing with a variety of failure modes. The treatment focuses on practical troubleshooting of blading problems augmented, in some cases, by the use of analytical tools. APPENDIX A provides applicable tools, rules of thumb, and formulae that can be used by gas turbine users for design review and troubleshooting

Aerothermal-Mechanical Health Monitoring And Diagnostics Or Turbo-Compressor Sets

PaperPg. 75-94.High speed turbomachinery plays a critical role in today's petrochemical industry. There are very high penalty costs associated with nonavailability and catastrophic failure of critical unspared trains. Additionally the fuel and maintenance costs over the life cycle of plant turbomachinery is very significant. Both of the above factors point to the need for health monitoring and diagnostic systems. The petrochemical industry has in the past placed a heavy emphasis on mechanical (vibration) analysis for both health monitoring and diagnostics. This paper presents a methodology in which both mechanical and aerothermal parameters are utilized for machinery health monitoring, prognosis and diagnosis

Gas Turbine Power Augmentation By Fogging Of Inlet Air.

LecturePg. 93-114Gas turbine output is a strong function of the ambient air temperature with power output dropping by 0.3 percent to 0.5 percent for every 1 F rise in ambient temperature. While this characteristic is inherent in any gas turbine, the effect can be severe on certain aeroderivative engines. This loss in output presents a significant problem to utilities, cogenerators, and independent power producers (IPPs) when electric demands are high during the hot months. In the petrochemical and process industry, the reduction in output of mechanical drive gas turbines curtails plant output. One way to counter this drop in output is to cool the inlet air. This paper briefly reviews cooling technologies and focuses on direct water fogging of the gas turbine inlet air. The paper provides a comprehensive overview of the state-of-the-art of inlet fogging systems and how they have been applied to gas turbines. The paper assists readers to make an assessment of the benefit that are derived from applying this technology to their gas turbines

An Overview Of Cogeneration Technology - Design, Operation And Maintenance.

LecturePg. 3-24The growth of cogeneration technology started in the 1960s, but has recently accelerated with several users interested in cogeneration applications. An overview of cogeneration technology is presented, with current experience and prospects, including problem areas, in cogeneration plants detailed. An emphasis is placed on gas turbine based cogeneration systems, as these will account for over 50 percent of the market in the future. As the literature covering cogeneration is so varied, several concepts with references are brought together. The area of reliability, availability and maintainability is addressed in depth, as this is an area where the literature is somewhat lacking. Some future concepts that will have an impact on cogeneration are also discussed, including the use of closed gas turbine cycles, fluidized beds and dual fluid cycles

Fouling Of Axial Flow Compressors - Causes, Effects, Detection, And Control.

LecturePg. 55-76The fouling of axial flow compressors is a serious operating problem in gas turbines and in process axial flow compressors. Gas turbines are being increasingly used in cogeneration applications and with the large air mass flowrate (e. g., 633 lb/sec for a 80 MW gas turbine) foulants even in the ppm range can cause deposits on the blading, resulting in a severe performance decrement. This is a common operating problem experienced by almost all operators of gas turbines. The effect of compressor fouling is a drop in air flow and compressor isentropic efficiency, which then manifests itself as a drop in power output and thermal efficiency. In some cases, fouling can also result in s urge problems as its effect is to move the compressor surge line to the right, i. e., towards the operating line. The mechanisms are discussed for fouling, the aerodynamic and thermodynamic effects, types of foulants, detection methods, and control techniques. A brief discussion on turbine fouling is also made

Historical Evolution Of Turbomachinery

Tutorialpg. 281-322This paper presents a comprehensive treatise of the antecedents, evolution, developments, and inventions relating to turbomachinery from early paddle wheels to modern turbojets emphasizing the constant challenge, failures, and problems faced by engineers as they strived toward developing higher performance turbomachinery. Both normal technology and radical innovations are covered. Radical innovations or technologies are those that allow quantum leaps in turbomachinery technology. Particular emphasis is paid to the turbojet revolution that occurred before and during the Second World War, which ended the dominance of the reciprocating engine for aircraft propulsion and spurred technological advancements, leading to today’s advanced turbomachines

Gas Turbine Axial Compressor Fouling And Washing.

Tutorialpg. 163-192The privatization of utilities, intense competition in the petrochemical and gas distribution industries, coupled with increasing fuel costs, have created a strong incentive for gas turbine operators to minimize and control performance deterioration. The most significant deterioration problem faced by gas turbine operators is compressor fouling. The effect of compressor fouling is a drop in airflow, pressure ratio, and compressor efficiency, resulting in a “rematching” of the gas turbine and compressor and a drop in power output and thermal efficiency. This paper provides a comprehensive practical treatment of the causes, effects, and control of fouling. Gas turbine inlet filtration, fouling mechanisms, and compressor washing are covered in detail. The major emphasis will be on compressor washing approaches, technology, and practical aspects. The complexities and challenges of online washing of large output new gas turbines will also be covered. The treatment also applies to axial air compressors used in the hydrocarbon processing industry