Fouling Mechanisms in Axial Compressors

2011 ◽  
Author(s):  
Rainer Kurz ◽  
Klaus Brun
Keyword(s):  
Surface Roughness ◽  
Gas Turbines ◽  
Air Filtration ◽  
Sea Salts ◽  
Compressor Blades ◽  
Axial Compressors ◽  
Performance Deterioration ◽  
Over Time

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.

Fouling Mechanisms in Axial Compressors

2012 ◽  
Vol 134 (3) ◽  
Author(s):  
Rainer Kurz ◽  
Klaus Brun
Keyword(s):  
Surface Roughness ◽  
Gas Turbines ◽  
Air Filtration ◽  
Sea Salts ◽  
Compressor Blades ◽  
Axial Compressors ◽  
Performance Deterioration ◽  
Over Time

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), with subsequent deterioration in performance. 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.

Experimental Evaluation of Compressor Blade Fouling

2016 ◽  
Author(s):  
Rainer Kurz ◽  
Grant Musgrove ◽  
Klaus Brun
Keyword(s):  
Boundary Layer ◽  
Gas Turbines ◽  
Blade Surface ◽  
Air Filtration ◽  
Ambient Conditions ◽  
Compressor Blades ◽  
Performance Deterioration ◽  
Quantitative Results ◽  
The Impact ◽  
Dust Retention

Fouling of compressor blades is an important mechanism leading to performance deterioration in gas turbines over time. Experimental and simulation data are available for the impact of specified amounts of fouling on performance, as well as the amount of foulants entering the engine for defined air filtration systems and ambient conditions. This study provides experimental data on the amount of foulants in the air that actually stick to a blade surface for different conditions of the blade surface. Quantitative results both indicate the amount of dust as well as the distribution of dust on the airfoil, for a dry airfoil, as well as airfoils that were wet from ingested water, as well as different types of oil. The retention patterns are correlated with the boundary layer shear stress. The tests show the higher dust retention from wet surfaces compared to dry surfaces. They also provide information about the behavior of the particles after they impact on the blade surface, showing that for a certain amount of wet film thickness, the shear forces actually wash the dust downstream, and off the airfoil. Further, the effect of particle agglomeration of particles to form larger clusters was observed, which would explain the disproportional impact of very small particles on boundary layer losses.

Experimental Evaluation of Compressor Blade Fouling

2016 ◽  
Vol 139 (3) ◽  
Author(s):  
Rainer Kurz ◽  
Grant Musgrove ◽  
Klaus Brun
Keyword(s):  
Boundary Layer ◽  
Gas Turbines ◽  
Blade Surface ◽  
Air Filtration ◽  
Ambient Conditions ◽  
Compressor Blades ◽  
Performance Deterioration ◽  
Quantitative Results ◽  
The Impact ◽  
Dust Retention

Fouling of compressor blades is an important mechanism leading to performance deterioration in gas turbines over time. Experimental and simulation data are available for the impact of specified amounts of fouling on the performance as well as the amount of foulants entering the engine for defined air filtration systems and ambient conditions. This study provides experimental data on the amount of foulants in the air that actually stick to a blade surface for different conditions. Quantitative results both indicate the amount of dust as well as the distribution of dust on the airfoil, for a dry airfoil, and also the airfoils that were wet from ingested water, in addition to, different types of oil. The retention patterns are correlated with the boundary layer shear stress. The tests show the higher dust retention from wet surfaces compared to dry surfaces. They also provide information about the behavior of the particles after they impact on the blade surface, showing for a certain amount of wet film thickness, the shear forces actually wash the dust downstream and off the airfoil. Further, the effect of particle agglomeration of particles to form larger clusters was observed, which would explain the disproportional impact of very small particles on boundary layer losses.

scholarly journals Operating Experience With Compressors of Large Heavy-Duty Gas Turbines

1984 ◽  
Author(s):  
B. Becker ◽  
D. Bohn
Keyword(s):  
Gas Turbines ◽  
Operating Performance ◽  
Operating Experience ◽  
Ambient Air ◽  
Solid Particles ◽  
Operating Efficiency ◽  
Compressor Blades ◽  
Dynamic Stresses ◽  
Axial Compressors ◽  
Shaft Power

The shaft power of compressors in industrial-type gas turbines exceeds that which is attained by any other axial compressors. Their operating efficiency and availability are thus of prime importance expecially since gas turbines are being increasingly utilized for medium-range and base-load electric power generation. In addition to good aerodynamic design of the blading, correct dimensioning of the compressor blades to withstand the static and dynamic stresses that occur under various service conditions is a decisively important prerequisite for reliable operating performance. Measurement of the dynamic stresses is important for design verification and reliability confirmation. Within the period between scheduled maintenance of a Model V 94 gas turbine, approx. 3,000 kg of solid particles flow through the compressor blading if the intake ambient air has a dust content of 0.1 mg/m3. The possible resulting erosion, corrosion and fowling negatively affect the long-term operating performance. The paper describes how these harmful effects can be effectively combatted by intake-air filtering, machine washing and blade coatings. The operating experience based on over one million service hours, of which more than one-third is with protected blades, demonstrates the success of the recommended compressor protection methods in achieving remarkably high operating availability.

Performance Deterioration of Intake Air Filters for Gas Turbines in Offshore Installations

2010 ◽  
Author(s):  
Olaf Brekke ◽  
Lars E. Bakken
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Oil And Gas ◽  
Operating Experience ◽  
Gas Production ◽  
Differential Pressure ◽  
Air Filtration ◽  
Turbine Inlet ◽  
Offshore Installations ◽  
Performance Deterioration

Efficient inlet air filtration is a key element for limiting fouling, erosion, and corrosion in the compressor section of offshore gas turbine installations. Current filtration systems are normally successful in preventing serious erosion and corrosion problems in the compressor section, but significant performance deterioration caused by compressor fouling still remains a challenge. This performance deterioration increases fuel consumption and emissions and has a particularly severe economic impact when it reduces oil and gas production. Operating experience from different offshore installations has shown that the deterioration rate in gas turbine performance increases when the turbines are operating in wet or humid weather and that the differential pressure loss over the intake system is affected by ambient humidity. An experimental test rig has been built in the laboratory at the Norwegian University of Science and Technology (NTNU) in order to increase understanding of the fundamentals related to gas turbine inlet air filtration. This paper presents the results from an experimental investigation of the performance of gas turbine inlet air filter elements that have been in operation offshore. Performance under both dry and wet conditions is assessed. Different types of filter elements show significantly different changes in differential pressure signature when exposed to moisture, and all of the tested filter elements demonstrate a loss of accumulated contamination after operating in wet conditions. Hence, contaminants originally accumulated by the filter elements are re-entrained into the airstream on the downstream side of the filters when they are exposed to moisture. The change in differential pressure signature as a result of operating in wet conditions demonstrates another weakness of solely applying differential pressure for condition monitoring of the filter system.

2-Stage Air Filtration for Gas Turbine Naval Applications

2019 ◽  
Author(s):  
Gianluca de Arcangelis
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Efficiency ◽  
Turbine Blades ◽  
Water Repellency ◽  
Air Filtration ◽  
Compressor Blades ◽  
Reduced Pressure ◽  
Filtration System ◽  
Offshore Oil

Abstract Traditional air filtration systems for Gas Turbine Naval applications consist of 3 stages: 1st vane separator + pocket filter + 2nd vane separator. The 2nd vane separator is required to drain out droplets formed by the traditional pocket filter during its coalescing function. Further to technological advancements in the water repellency of filter media, as well as leak-free techniques, it is now possible to implement a pocket filter that avoids leaching water droplets downstream. This enables the elimination of the 3rd stage vane separator in the air filtration system. The result is a suitable 2-stage air filtration system. The elimination of the 3rd stage vane separator provides the obvious following advantages: • Reduced pressure drop • Reduced weight • Reduced foot-print • Reduced cost Latest technological advancements in water repellency and high efficiency melt-blown media also allow the attainment of higher performance such as: • Increased efficiency against water droplet and salt in wet state • Increased efficiency against dry salt and dust This results in higher cleanliness of the Gas Turbines with benefits in terms of compressor fouling, compressor blades corrosion and turbine blades hot erosion. Higher performance also results in simplified maintenance as technicians need only focus on the replacement of the elements as opposed to the cleaning and overhauling of the intake duct. The paper goes through the engineering challenges of evolving from a 3-stage to 2-stage filtration system. The paper provides data from testing at independent laboratories with results that back the claims. Furthermore, reference is made to Offshore Oil & Gas installations and testing that have proven successful with independently measured data.

The Impact of Surface Roughness on Axial Compressor Performance Deterioration

2006 ◽  
Author(s):  
Elisabet Syverud ◽  
Lars E. Bakken
Keyword(s):  
Surface Roughness ◽  
Test Data ◽  
Gas Turbines ◽  
Axial Compressor ◽  
Flow Coefficient ◽  
Published Data ◽  
Flow Mechanisms ◽  
Performance Deterioration ◽  
Compressor Performance ◽  
The Impact

Axial compressor deterioration due to removable deposits is a major concern in the operation of gas turbines. It is important to fully understand the flow mechanisms in order to successfully monitor and clean the engine. A test program on the GE J85-13 jet engine quantified the increased surface roughness and the distribution of salt deposits in an axial compressor. The test data showed good agreement with published data for stage performance deterioration. This paper compares the GE J85-13 test data on surface roughness to previously published work on surface roughness in compressors. The effect of surface roughness on the stage characteristics is modeled using theory for frictional losses, blockage and deviation. The results are compared to test data. The most significant effect of increased roughness is found to be the variation in the flow coefficient.

Influence of Surface Roughness on the Performance of a Compressor Blade in a Linear Cascade: Experiment and Modeling

2009 ◽  
Author(s):  
Seung Chul Back ◽  
In Cheol Jeong ◽  
Jeong Lak Sohn ◽  
Seung Jin Song
Keyword(s):  
Surface Roughness ◽  
Mass Flow Rate ◽  
Mass Flow ◽  
Flow Rate ◽  
Gas Turbines ◽  
Compressor Blade ◽  
Blade Surface ◽  
Compressor Blades ◽  
Linear Cascade ◽  
Multi Stage

Compressor blades experience significant surface degradation with service. Elevated levels of surface roughness reduce compressor efficiency and mass flow rate. This paper presents measurement and a new model of compressor blade performance degradation due to blade surface roughness. Performance tests have been conducted in a low-speed, linear cascade with roughened compressor blades. Equivalent sandgrain roughnesses of 12, 180, 300, 425, and 850 microns have been tested. These roughness values are representative of compressor blade roughnesses found in actual gas turbines in service. Flow angle, flow rate, and loss have been measured. For the tested roughnesses of 180, 300, 425, and 850 microns, the axial velocity ratio decreases by 0.1, 2.1, 2.5, and 5.4%, respectively. For the same cases, the deviation increases by 24, 38, 51, and 70%, respectively. Finally, the loss increases by 12, 44, 132, and 217%, respectively. Thus, among the three parameters, the loss responds most sensitively to changes in compressor blade roughness. Furthermore, a new mean-line model based on the assumption of 50% reaction stages has been developed to estimate the effects of roughness on the performance of a multi-stage compressor. The data from the cascade data are used as input to predict the performance of a single compressor stage. Subsequently, a stage-stacking method is used to enable prediction for a multi-stage compressor. According to the model, the pressure ratio, and mass flow rate are significantly influenced by the blade surface roughness.

Strategy for Selecting Optimised Technologies for Gas Turbine Air Inlet Filtration Systems

2011 ◽  
Author(s):  
Stephen D. Hiner
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Fuel Quality ◽  
Air Filtration ◽  
Air Inlet ◽  
Filtration System ◽  
The World ◽  
Maintenance Requirements ◽  
Specific Challenge ◽  
Over Time

With continuous advances in gas turbine technology, wider breadth of fuel quality burnt and ever growing expectations of; longer life, higher efficiency and reduced maintenance requirements, the filtration of the air entering the gas turbine (GT) has never been more important to meeting its operational requirements. Gas turbines are used throughout the world in an ever increasing diversity of application and environment. This presents a number of challenges to the air filtration system, that require unique solutions for each subset of environment specific challenge, gas turbine platform technology and fuel quality being burnt. This paper discusses the importance of air filtration to a modern GT and how this has changed over time and it’s shifting operational requirements. It explores the challenges facing the air filtration system presented by the different; environments, GT technologies and fuel quality. The paper details what approaches and filtration technologies are currently used to address these challenges, with strengths and weaknesses explained as appropriate, to finally present a strategy for specifying an optimized filtration system to meet the challenges of the modern GT.

Evolution of Gas Turbine Intake Air Filtration in a 420 MW Cogeneration Plant

2014 ◽  
Author(s):  
Steve Ingistov ◽  
Michael Milos ◽  
Rakesh K. Bhargava
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Economic Benefits ◽  
Cogeneration Plant ◽  
Air Filtration ◽  
Air Filter ◽  
Filter System ◽  
Turbine Performance ◽  
Filtration System ◽  
Operational Data

A suitable inlet air filter system is required for a gas turbine, depending on installation site and its environmental conditions, to minimize contaminants entering the compressor section in order to maintain gas turbine performance. This paper describes evolution of inlet air filter systems utilized at the 420 MW Watson Cogeneration Plant consisting of four GE 7EA gas turbines since commissioning of the plant in November 1987. Changes to the inlet air filtration system became necessary due to system limitations, a desire to reduce operational and maintenance costs, and enhance overall plant performance. Based on approximately 2 years of operational data with the latest filtration system combined with other operational experiences of more than 25 years, it is shown that implementation of the high efficiency particulate air filter system provides reduced number of crank washes, gas turbine performance improvement and significant economic benefits compared to the traditional synthetic media type filters. Reasons for improved gas turbine performance and associated economic benefits, observed via actual operational data, with use of the latest filter system are discussed in this paper.

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