With privatization and intense competition in the utility and petrochemical industry, there is a strong incentive for gas turbine operators to minimize and control performance deterioration, as this directly affects profitability. The area of gas turbine recoverable and nonrecoverable performance deterioration is comprehensively treated in this paper. Deterioration mechanisms including compressor and turbine fouling, erosion, increased clearances, and seal distress are covered along with their manifestations, rules of thumb, and mitigation approaches. Permanent deterioration is also covered. Because of the importance of compressor fouling, gas turbine inlet filtration, fouling mechanisms, and compressor washing are covered in detail. Approaches for the performance monitoring of steady-state and transient behavior are presented along with simulations of common deterioration modes of gas turbine combined cycles. As several gas turbines are used in cogeneration and combined cycles, a brief discussion of heat recovery steam generator performance monitoring is made.

Gas Turbine Performance Deterioration.

Engineer, Turbomachinery Group, LNG Product Development Center, with Bechtel Corporation, in Houston, Texas. His 25 years of industry experience encompasses turbomachinery design, engine development, vibration and failure analysis, and the testing of gas turbines and compressors. He has developed several aerothermal and transient analysis techniques for the condition monitoring of gas turbines. In the past he was Chief Engineer of Mee Industries, Gas Turbine Division, and Boyce Engineering International Inc. Mr. Meher-Homji has a B.S. degree (Mechanical Engineering) from Shivaji University, an M.E. degree from Texas A&M University, and an MBA from the University of Houston. He is a member and past Chair of ASME’s International Gas Turbine Institute’s Industrial and Cogeneration Committee. Mr. MeherHomji was named Fellow of the ASME in 1997. He is a registered Professional Engineer in the State of Texas, and has several publications in the area of turbomachinery engineering.

Gas Turbine Axial Compressor Fouling And Washing.

Fouling of compressor blades is an important mechanism leading to performance deterioration in gas turbines over time. Fouling is caused by the adherence of particles to airfoils and annulus surfaces. Particles that cause fouling are typically smaller than 2 to 10 microns. Smoke, oil mists, carbon, and sea salts are common examples. Fouling can be controlled by appropriate air filtration systems, and can often be reversed to some degree by detergent washing of components. The adherence of particles is impacted by oil or water mists. The result is a build-up of material that causes increased surface roughness and to some degree changes the shape of the airfoil (if the material build up forms thicker layers of deposits). Fouling mechanisms are evaluated based on observed data, and a discussion on fouling susceptibility is provided. A particular emphasis will be on the capabilities of modern air filtration systems.Copyright © 2011 by Solar Turbines Inc.

Fouling Mechanisms in Axial Compressors

Gas-path diagnostics is an essential part of gas turbine (GT) condition-based maintenance (CBM). There exists extensive literature on GT gas-path diagnostics and a variety of methods have been introduced. The fundamental limitations of the conventional methods such as the inability to deal with the nonlinear engine behavior, measurement uncertainty, simultaneous faults, and the limited number of sensors available remain the driving force for exploring more advanced techniques. This review aims to provide a critical survey of the existing literature produced in the area over the past few decades. In the first section, the issue of GT degradation is addressed, aiming to identify the type of physical faults that degrade a gas turbine performance, which gas-path faults contribute more significantly to the overall performance loss, and which specific components often encounter these faults. A brief overview is then given about the inconsistencies in the literature on gas-path diagnostics followed by a discussion of the various challenges against successful gas-path diagnostics and the major desirable characteristics that an advanced fault diagnostic technique should ideally possess. At this point, the available fault diagnostic methods are thoroughly reviewed, and their strengths and weaknesses summarized. Artificial intelligence (AI) based and hybrid diagnostic methods have received a great deal of attention due to their promising potentials to address the above-mentioned limitations along with providing accurate diagnostic results. Moreover, the available validation techniques that system developers used in the past to evaluate the performance of their proposed diagnostic algorithms are discussed. Finally, concluding remarks and recommendations for further investigations are provided.

A Review on Gas Turbine Gas-Path Diagnostics: State-of-the-Art Methods, Challenges and Opportunities

The paper describes the phenomenon of axial compressor fouling due to aerosols contained in the air. Key parameters having effect on the level of fouling are determined. A mathematical model of a progressive compressor fouling using the stage-by-stage calculation method is developed. Calculation results on the influence of fouling on the compressor performance are presented. A new index of sensitivity of axial compressors to fouling is suggested. The paper gives information about Turbotect`s deposit cleaning method of compressor blading and the results of its application on an operating industrial gas turbine. Regular on-line and off-line washings of the compressor flow path made it possible to maintain a high level of engine efficiency and output.

An analysis of axial compressor fouling and a blade cleaning method

Although the overall effect of compressor fouling on engine performance has been recognized for many years, remarkably little has been published on the quantifiable effects. Mathematical modelling of compressors using stage stacking methods has recently been used for a systematic study of compressor fouling and earlier investigations led to an interest in the effects of engine size and compressor stage loading. This paper presents a proposed index showing the susceptibility of compressors to fouling, which could be useful in helping operators to determine cleanup intervals. Three engines of widely differing performance were used in developing this index and additional operator experience would be useful in confirming its validity.Copyright © 1990 by ASME

A Proposed Method for Assessing the Susceptibility of Axial Compressors to Fouling

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F. Seddigh

Papers

A Proposed Method for Assessing the Susceptibility of Axial Compressors to Fouling

A Proposed Method for Assessing the Susceptibility of Axial Compressors to Fouling