Gas Turbine Fouling Offshore: An Analysis of Engine Air Flow

2018 ◽  
Author(s):  
Stian Madsen ◽  
Mehmet Serkan Yildirim ◽  
Lars E. Bakken
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Air Flow ◽  
Peak Load ◽  
Field Measurements ◽  
High Water ◽  
Additional Parameter ◽  
Ambient Conditions ◽  
Successful Operation ◽  
Performance Deterioration

Optimized operation of gas turbines is discussed for a fleet of eleven LM2500PE engines at a Statoil North Sea offshore field i n Norway. Three engines are generator drivers whilst eight engines are compressor drivers. Several of the compressor drive engines are running at peak load (T5.4 control), hence the production rate is limited by the available power from these engines. The majority of the engines discussed run continuously without redundancy, hence gas turbine uptime is critical for the field’s production and economy. Two of the compressor drive engines are instrumented with a new static P2 probe in order to have an inlet depression measurement and thus be able to monitor compressor air flow. Compressor air flow has been used as an additional parameter to efficiency, in order to have better analysis methods and better documentation of deterioration rates. The performance gain with online water wash at high water-to-air ratio and upgraded inlet air filter systems, as well as successful operation at longer intervals between offline wash/maintenance stops are thus documented. An approach for developing a compressor map for mass flow based on field measurements, predictions and deterioration has been performed, as well as correction methods for engine load and ambient conditions in order to be able to compare performance points in various conditions and engine control modes. When monitoring compressor air flow, the Reynolds number effects on axial compressor performance can be analyzed. Understanding the gas turbine performance deterioration is of vital importance. Trending of its deviation from the engine baseline facilitates load-independent monitoring of the gas turbine’s condition. Instrument resolution and repeatability are key factors in order to have reasonable results on the performance analysis. Based on previous tests and analysis, the compressor air flow rate is the most sensitive parameter for detecting performance deterioration. Unfortunately, gas turbines for offshore operation, are normally not equipped with any air flow measurement devices.

Gas Turbine Fouling Offshore: Effective Online Water Wash Through High Water-to-Air Ratio

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Stian Madsen ◽  
Lars E. Bakken
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Peak Load ◽  
Engine Performance ◽  
High Water ◽  
Operational Experience ◽  
Successful Operation ◽  
Water Rate ◽  
Offshore Field ◽  
Key Parameter

Optimized operation of gas turbines is discussed for a fleet of 11 GE LM2500PE engines at a Statoil North Sea offshore field in Norway. Three engines are generator drivers, and eight engines are compressor drivers. Several of the compressor drive engines are running at peak load (T5.4 control), hence, the production rate is limited by the available power from these engines. The majority of the engines discussed run continuously without redundancy, hence, the gas turbine uptime is critical for the field's production and economy. The performance and operational experience with online water wash at high water-to-air ratio (w.a.r.), as well as successful operation at longer maintenance intervals and higher average engine performance are described. The water-to-air ratio is significantly increased compared to the original equipment manufacturer (OEM) limit (OEM limit is 17 l/min which yields approximately 0.5% water-to-air ratio). Today the engines are operated at a water rate of 50 l/min (three times the OEM limit) which yields a 1.4% water-to-air ratio. Such a high water-to-air ratio has been proven to be the key parameter for obtaining good online water wash effectiveness. Possible downsides of high water-to-air ratio have been thoroughly studied.

Gas Turbine Fouling Offshore: Effective Online Water Wash Through High Water-to-Air Ratio

2018 ◽  
Author(s):  
Stian Madsen ◽  
Lars E. Bakken
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Peak Load ◽  
Engine Performance ◽  
High Water ◽  
Total Efficiency ◽  
Operational Experience ◽  
Successful Operation ◽  
Term Operation ◽  
The Subject

Optimized operation of gas turbines is discussed for a fleet of eleven GE LM2500PE engines at a Statoil North Sea offshore field in Norway. Three engines are generator drivers and eight engines are compressor drivers. Several of the compressor drive engines are running at peak load (T5.4 control), hence production rate is limited by the available power from these engines. The majority of the engines discussed run continuously without redundancy, hence gas turbine uptime is critical for the field’s production and economy. The performance and operational experience with online water wash at high water-to-air ratio, as well as successful operation at longer maintenance intervals and higher average engine performance are described. This work is based on long-term operation with online washing, where operational data are collected and performance is analyzed over a 10-year period. Today, all engines are operated with 6-month intervals between maintenance stops, where offline crank wash is performed as well as other necessary maintenance and repairs. Online washing is performed daily between the maintenance stops at full load (i.e. normal operating load for the subject engine). To keep the engine as clean as possible and reduce degradation between maintenance stops, both an effective online water wash system and an effective air intake filter system are critical factors. The overall target is to maintain high engine performance, and extend the interval between maintenance stops through effective online washing. Water-to-air ratio is significantly increased compared to the OEM limit (OEM limit is 17 l/min which yields approx. 0.5% water-to-air ratio). Today the engines are operated at a water rate of 50 l/min (3 times the OEM limit) which yields a 1.4% water-to-air ratio. Such a high water-to-air ratio has been proven to be the key parameter for obtaining good online water wash effectiveness. Possible downsides of high water-to-air ratio have been thoroughly studied. The effect of optimized online water wash for the subject engines is longer intervals between maintenance stops, higher power availability, lower engine performance deterioration and reduced emissions (CO2 and NOx). The operating intervals are now extended to six months (4,000 hours), from initially two months (1,500 hours, early 1990s) followed by four months (3,000 hours, mid-2000s). Other installations operated as low as 750 hours between offline washes in the 1980s and 1990s. Of a total efficiency deterioration improvement of 6% over each 6-month operating period, the deterioration is reduced by an estimated 3% related to online water wash.

Gas Turbine Fouling Offshore: Air Intake Filtration Optimization

2018 ◽  
Author(s):  
Stian Madsen ◽  
Jørn Watvedt ◽  
Lars E. Bakken
Keyword(s):  
Gas Turbine ◽  
North Sea ◽  
Gas Turbines ◽  
High Efficiency ◽  
Salt Content ◽  
Peak Load ◽  
Operational Experience ◽  
Successful Operation ◽  
Filter System ◽  
Air Intake

Optimized operation of gas turbines is discussed for a fleet of eleven LM2500PE engines at a Statoil North Sea offshore field in Norway. Three engines are generator drivers while eight engines are compressor drivers. Several of the compressor drive engines run at peak load (T5.4 control), hence production rate is limited by the available power from these engines. The majority of the engines discussed run continuously without redundancy, hence gas turbine uptime is critical for the field’s production and economy. The performance and operational experience with upgraded inlet air filter systems, as well as successful operation at longer maintenance intervals and higher average engine performance are described. For North Sea operation, a key property of the filter system is the ability to handle high humidity and high salt-content, typical of the harsh environment in these waters. The upgraded filter system analyzed in this paper is a 2-stage system (vane separator stage upstream of the high-efficiency filter stage), which is a simplified design versus the old traditional 3-stage systems (louvre upstream and vane separator downstream of the filter stage). These 2-stage systems rely on an efficient upstream vane separator to remove the vast majority of water from the airflow before it reaches the high-efficiency filters. The high-efficiency filters are specially designed to withstand moisture. The effectiveness and contribution of each component in the filtration system are described. Extensive testing of both new and used filter elements, of different filter grade and operated at different intervals, has been performed in a filter test rig facility onshore. Extensive testing of used filters has also been performed at the filter OEM, where filter efficiency is measured as well as destructive testing and analysis of the filter layers. The effect of an optimized air intake filter system for the subject engines, is longer operating intervals, higher power availability and lower engine deterioration. The operating intervals are now extended to six months (4,000 hours), from initially two months (1,500 hours, early 1990s) then four months (3,000 hours, mid 2000s). The HPC efficiency deterioration is reduced by some 3% related to intake filter system, of a total of over 6% in efficiency deterioration over each 6-month operating period.

Power Augmentation Study of an Existing Combined Cycle Power Plant by Overspray Inlet Fogging

2008 ◽  
Author(s):  
Hsiao-Wei D. Chiang ◽  
Pai-Yi Wang ◽  
Hsin-Lung Li
Keyword(s):  
Power Plant ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Peak Load ◽  
Combined Cycle ◽  
Ambient Conditions ◽  
Combined Cycle Power Plant ◽  
Combined Cycles ◽  
Increasing Demand

With increasing demand for power and with shortages envisioned especially during the peak load times during the summer, there is a need to boost gas turbine power. In Taiwan, most of gas turbines operate with combined cycle for base load. Only a small portion of gas turbines operates with simple cycle for peak load. To prevent the electric shortage due to derating of power plants in hot days, the power augmentation strategies for combined cycles need to be studied in advance. As a solution, our objective is to add an overspray inlet fogging system into an existing gas turbine-based combined cycle power plant (CCPP) to study the effects. Simulation runs were made for adding an overspray inlet fogging system to the CCPP under various ambient conditions. The overspray percentage effects on the CCPP thermodynamic performance are also included in this paper. Results demonstrated that the CCPP net power augmentation depends on the percentage of overspray under site average ambient conditions. This paper also included CCPP performance parametric studies in order to propose overspray inlet fogging guidelines for combined cycle power augmentation.

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.

scholarly journals Gas Turbine Health State Determination: Methodology Approach and Field Application

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
Mauro Venturini
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Field Measurements ◽  
Field Application ◽  
Diagnostic Process ◽  
Health State ◽  
Gas Compression ◽  
State Determination ◽  
Measurement Validation ◽  
Machine Health

A reduction of gas turbine maintenance costs, together with the increase in machine availability and the reduction of management costs, is usually expected when gas turbine preventive maintenance is performed in parallel to on-condition maintenance. However, on-condition maintenance requires up-to-date knowledge of the machine health state. The gas turbine health state can be determined by means of Gas Path Analysis (GPA) techniques, which allow the calculation of machine health state indices, starting from measurements taken on the machine. Since the GPA technique makes use of field measurements, the reliability of the diagnostic process also depends on measurement reliability. In this paper, a comprehensive approach for both the measurement validation and health state determination of gas turbines is discussed, and its application to a 5 MW gas turbine working in a natural gas compression plant is presented.

Gas Turbine Fouling Offshore: Correction Methodology Compressor Efficiency

2017 ◽  
Author(s):  
Stian Madsen ◽  
Lars E. Bakken
Keyword(s):  
Gas Turbine ◽  
Peak Load ◽  
Operational Experience ◽  
Air Filtration ◽  
Ambient Conditions ◽  
Key Factors ◽  
Turbine Performance ◽  
Main Challenge ◽  
Filtration System ◽  
Compressor Efficiency

Gas turbine performance has been analyzed for a fleet of GE LM2500 engines at two Statoil offshore fields in the North Sea. Both generator drive engines and compressor driver engines have been analyzed, covering both the LM2500 base and plus configurations, as well as the SAC and DLE combustor configurations. Several of the compressor drive engines are running at peak load (T5.4 control), and the production rate is thus limited to the available power from these engines. The majority of the engines discussed run continuously without redundancy, implying that gas turbine uptime is critical for the field’s production and economy. Previous studies and operational experience have emphasized that the two key factors to minimize compressor fouling are the optimum designs of the inlet air filtration system and the water wash system. An optimized inlet air filtration system, in combination with daily online water wash (at high water-to-air ratio), are the key factors to achieve successful operation at longer intervals between offline washes and higher average engine performance. Operational experience has documented that the main gas turbine recoverable deterioration is linked to the compressor section. The main performance parameter when monitoring compressor fouling is the gas turbine compressor efficiency. Previous studies have indicated that inlet depression (air mass flow at compressor inlet) is a better parameter when monitoring compressor fouling, whereas instrumentation for inlet depression is very seldom implemented on offshore gas turbine applications. The main challenge when analyzing compressor efficiency (uncorrected) is the large variation in efficiency during the periods between offline washes, mainly due to operation at various engine loads and ambient conditions. Understanding the gas turbine performance deterioration is of vital importance. Trending of the deviation from the engine baseline facilitates load-independent monitoring of the gas turbine’s condition. Instrument resolution and repeatability are key factors for attaining reliable results in the performance analysis. A correction methodology for compressor efficiency has been developed, which improves the long term trend data for effective diagnostics of compressor degradation. Avenues for further research and development are proposed in order to further increase the understanding of the deterioration mechanisms, as well as gas turbine performance and response.

Early Fault Detection of Hot Components in Gas Turbines

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Liu Jinfu ◽  
Liu Jiao ◽  
Wan Jie ◽  
Wang Zhongqi ◽  
Yu Daren
Keyword(s):  
Fault Detection ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Working Environment ◽  
Detection Sensitivity ◽  
Normal Operation ◽  
Large Temperature ◽  
Ambient Conditions ◽  
Fisher Discriminant Analysis ◽  
Early Fault Detection

The working environment of hot components is the most adverse of all gas turbine components. Malfunction of hot components is often followed by catastrophic consequences. Early fault detection plays a significant role in detecting performance deterioration immediately and reducing unscheduled maintenance. In this paper, an early fault detection method is introduced to detect early fault symptoms of hot components in gas turbines. The exhaust gas temperature (EGT) is usually used to monitor the performance of the hot components. The EGT is measured by several thermocouples distributed equally at the outlet of the gas turbine. EGT profile is symmetrical when the unit is in normal operation. And the faults of hot components lead to large temperature differences between different thermocouple readings. However, interferences can potentially affect temperature differences, and sometimes, especially in the early stages of the fault, its influence can be even higher than that of the faults. To improve the detection sensitivity, the influence of interferences must be eliminated. The two main interferences investigated in this study are associated with the operating and ambient conditions, and the structure deviation of different combustion chambers caused by processing and installation errors. Based on the basic principles of gas turbines and Fisher discriminant analysis (FDA), a new detection indicator is presented that characterizes the intrinsic structure information of the hot components. Using this new indicator, the interferences involving the certainty and the uncertainty are suppressed and the sensitivity of early fault detection in gas turbine hot components is improved. The robustness and the sensitivity of the proposed method are verified by actual data from a Taurus 70 gas turbine produced by Solar Turbines.

Rosenhain Centenary Conference - 1. Engineering requirements 1.6 Gas turbine requirements Discussion

1976 ◽  
Vol 282 (1307) ◽  
pp. 123-130
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
High Strain ◽  
Peak Load ◽  
Great Majority ◽  
Growth Monitoring ◽  
Fuel Quality ◽  
High Sodium ◽  
Power Stations ◽  
Operational Life

The C.E.G.B. interest in gas turbines has developed steadily during the past decade from auxiliary service functions in large fossil-fuelled power stations to small power stations, entirely of gas turbine plant, whose principal purpose is to meet peak load demands. Here the ability of the gas turbine to be started up very rapidly is an important attribute. The great majority of these gas turbine units have been derived from the use of established aero engines, such as the Avon and Olympus, as gas generators to drive a power turbine. These units are subject to planned maintenance after, at the most, 2000 h of operation when burning distillate fuel. There have been instances of blade corrosion problems due to sulphidation attack and related high sodium levels in the fuel; the solution to this problem has been to control the fuel quality. Two prototype industrial gas turbines, each of ca. 55 MW output, are due to be commissioned at one of the Board’s power stations in the near future. Here the aimed-for operational life before undertaking planned maintenance will be ca. 20000 h. This places greater emphasis on the need to appreciate any time-dependent process affecting engineering performance. From a materials standpoint these are corrosion resistance, thermal and high strain fatigue and creeprupture. Specific problems under study in blade materials are the consequences of corrosion-resistant coatings upon the mechanical properties and the limits of acceptability of defects. The latter involves crack growth monitoring under conditions of creep, high strain and high cycle fatigue. As the future emphasis should be directed towards gaining a better understanding of material behaviour in the projected engineering situations the physical metallurgist has to think beyond the metals themselves and consider, for example, the interactions that occur between metals and coatings.

Numerical Assessment of SCAP: A Passive System for Preventing Thermoacoustic Oscillations in Gas Turbine Annular Combustors

2007 ◽  
Author(s):  
Stefano Tiribuzi
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Research Unit ◽  
Combined Cycle ◽  
Computational Time ◽  
Computational Domain ◽  
Ambient Conditions ◽  
Pressure Oscillations ◽  
Operation Conditions ◽  
Thermoacoustic Oscillations

ENEL operates a dozen combined cycle units whose V94.3A gas turbines are equipped with annular combustors. In such lean premixed gas turbines, particular operation conditions could trigger large pressure oscillations due to thermoacoustic instabilities. The ENEL Research unit is studying this phenomenon in order to find out methods which could avoid or mitigate such events. The use of effective numerical analysis techniques allowed us to investigate the realistic time evolution and behaviour of the acoustic fields associated with this phenomenon. KIEN, an in-house low diffusive URANS code capable of simulating 3D reactive flows, has been used in the Very Rough Grid approach. This approach permits the simulation, with a reasonable computational time, of quite long real transients with a computational domain extended over all the resonant volumes involved in the acoustic phenomenon. The V94.3A gas turbine model was set up with a full combustor 3D grid, going from the compressor outlet up to the turbine inlet, including both the annular plenum and the annular combustion chamber. The grid extends over the entire circular angle, including all the 24 premixed burners. Numerical runs were performed with the normal V94.3A combustor configuration, with input parameters set so as no oscillations develop in the standard ambient conditions. Wide pressure oscillations on the contrary are associated with the circumferential acoustic modes of the combustor, which have their onset and grow when winter ambient conditions are assumed. These results also confirmed that the sustaining mechanism is based on the equivalence ratio fluctuation of premix mixture and that plenum plays an important role in such mechanism. Based on these findings, a system for controlling the thermoacoustic oscillation has been conceived (Patent Pending), which acts on the plenum side of the combustor. This system, called SCAP (Segmentation of Combustor Annular Plenum), is based on the subdivision of the plenum annular volume by means of a few meridionally oriented walls. Repetition of KIEN runs with a SCAP configuration, in which a suitable number of segmentation walls were properly arranged in the annular plenum, demonstrated the effectiveness of this solution in preventing the development of wide thermoacoustic oscillations in the combustor.

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