Managing Fuel Oil Nozzle Coking to Improve Gas Turbine Availability

2000 ◽  
Author(s):  
Leo R. Burgett ◽  
Tim Mercer
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Fuel Oil ◽  
Power Company ◽  
Ac Motor ◽  
Air System ◽  
Oil Residue ◽  
Cooling Air ◽  
Fuel Burner

Fuel oil nozzle coking has been a continuing problem for operators of gas turbine power plants. Over the years, several “solutions” to eliminate the coking of the fuel oil have been implemented to improve plant reliability and availability. When the fuel oil nozzle is “coked”, the startup and operation of the gas turbine are impaired and an unscheduled outage is needed to clean the fuel oil nozzle. In 1997, a project was initiated to investigate the coking problem as it affects the operation of the dual fuel burner of the ABB ALSTOM POWER Inc. GT11N1 single burner (SBK) gas turbine. The GT11N1 SBK fuel oil nozzle (see FIGURE 1) was failing to operate properly because of “coked” fuel oil residue on its internal components (stationary and moveable). ABB ALSTOM POWER Inc. teamed with Savannah Electric & Power Company and collected data that indicated adequate nozzle cooling air could reduce the rate of fuel oil coking. A nozzle cooling air system modification was installed on one of the ABB ALSTOM POWER Inc. 11N1 gas turbines at the Savannah Electric & Power Company McIntosh Power Plant. The modification included an AC motor driven air blower to provide cooling air to the fuel oil nozzle after shutdown of the gas turbine. Inspection of the components inside the fuel oil nozzle showed that very little fuel oil oxidation had occurred inside the nozzle during the three-month test period. By improving the fuel oil nozzle cooling air system, the coking problem can be better managed.

scholarly journals Cooling and Sealing Air System in Industrial Gas Turbine Engines

1996 ◽  
Author(s):  
A. W. Reichert ◽  
M. Janssen
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
State Of The Art ◽  
Cooling System ◽  
Inlet Temperature ◽  
Turbine Inlet ◽  
Air System ◽  
Calculation System ◽  
Cooling Air

Siemens heavy duty Gas Turbines have been well known for their high power output combined with high efficiency and reliability for more than 3 decades. Offering state of the art technology at all times, the requirements concerning the cooling and sealing air system have increased with technological development over the years. In particular the increase of the turbine inlet temperature and reduced NOx requirements demand a highly efficient cooling and sealing air system. The new Vx4.3A family of Siemens gas turbines with ISO turbine inlet temperatures of 1190°C in the power range of 70 to 240 MW uses an effective film cooling technique for the turbine stages 1 and 2 to ensure the minimum cooling air requirement possible. In addition, the application of film cooling enables the cooling system to be simplified. For example, in the new gas turbine family no intercooler and no cooling air booster for the first turbine vane are needed. This paper deals with the internal air system of Siemens gas turbines which supplies cooling and sealing air. A general overview is given and some problems and their technical solutions are discussed. Furthermore a state of the art calculation system for the prediction of the thermodynamic states of the cooling and sealing air is introduced. The calculation system is based on the flow calculation package Flowmaster (Flowmaster International Ltd.), which has been modified for the requirements of the internal air system. The comparison of computational results with measurements give a good impression of the high accuracy of the calculation method used.

Experimental and Numerical Analysis of the Flow Structure and Dust Separation Inside a Pre-Swirl Cooling Air System

2003 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
F.-K. Benra ◽  
D. Brillert
Keyword(s):  
Numerical Analysis ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Flow Conditions ◽  
Test Rig ◽  
Complex Flow ◽  
Air System ◽  
Cooling Air

Improvements in efficiency and performance of gas turbines require a better understanding of the internal cooling air system which provides the turbine blades with cooling air. With the increase of cooling air passing through the internal air system, a greater amount of air borne particles is transported to the film cooling holes at the turbine blade surface. In spite of their small size, these holes are critical for blockage. Blockage of only a few holes could have harmful effects on the cooling film surrounding the blade. As a result, a reduced mean time between maintenance or even unexpected operation faults of the gas turbine during operation could occur. Experience showed a complex interaction of cooling air under different flow conditions and its particle load. To get more familiar with all these influences and the system itself, a test rig has been built. With this test rig, the behavior of particles in the internal cooling air system can be studied at realistic flow conditions compared to a modern, heavy duty gas turbine. It is possible to simulate different particle sizes and dust concentrations in the coolant air. The test rig has been designed to give information about the quantity of separated particles at various critical areas of the internal air system [1]. The operation of the test rig as well as analysis of particles in such a complex flow system bear many problems, addressed in previous papers [1,2,3]. New theoretical studies give new and more accurate results, compared to the measurements. Furthermore the inspection of the test rig showed dust deposits at unexpected positions of the flow path, which will be discussed by numerical analysis.

The Approach to the Development of the Next Generation Gas Turbine and History of Tohoku Electric Power Company Combined Cycle Power Plants

2011 ◽  
Author(s):  
Yoshiaki Nishimura ◽  
Sadahiro Ohno ◽  
Shinya Ishikawa ◽  
Junichiro Masada ◽  
Kazumasa Takata
Keyword(s):  
Electric Power ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Combined Cycle ◽  
Closed Circuit ◽  
Pollutant Emission ◽  
Next Generation ◽  
Power Company ◽  
Electric Power Company

As global warming becomes increasingly serious, Japan has committed to reduce the CO2 emission by 25% from 1990 levels in Japan with preconditions by the end of 2020. To reach such the difficult target, resources and energy utilizations should be more efficient than before. Tohoku Electric Power Company, Inc. (Tohoku-EPCO) has been adopting the cutting-edge gas turbines for combined cycle power plants to contribute to the reduction of energy consumption and pollutant emission. Now Tohoku-EPCO and Mitsubishi Heavy Industries, Ltd. (MHI) have started a study of next generation gas turbines to further improve the gas turbine combined cycle (GTCC) power plants efficiency. Tohoku-EPCO and MHI have invented a “closed circuit air cooling system” and a trial design of the closed circuit air cooled combustor is now being conducted as a collaborative project. Besides, the material technology development is being conducted for the further increase in the turbine Row 1 vane inlet temperature (TIT) in future.

A Contribution to the Abrasive Effect of Particles in a Gas Turbine Pre-Swirl Cooling Air System

2005 ◽  
Author(s):  
O. Schneider ◽  
F.-K. Benra ◽  
H. J. Dohmen ◽  
K. Jarzombek
Keyword(s):  
Gas Turbine ◽  
Flow Structure ◽  
Film Cooling ◽  
Gas Turbines ◽  
Test Rig ◽  
Critical Areas ◽  
Air System ◽  
Quantitative Results ◽  
Film Cooling Holes ◽  
Cooling Air

With the increase of cooling air passing through the internal air system of modern gas turbines, a greater number of airborne particles is transported to the film cooling holes in the turbine blade surface. In spite of their small size, these holes are critical for airflow and must be free of blockage. A test rig has been designed to study the quantity of separated particles at various critical areas of the internal air system. Former publications for this conference gave detailed insight into the test rig, the flow structure and the particle motion during separation. The process of separation generates abrasion on the rotating and stationary parts of the system. When considering service and maintenance or even unexpected operation faults of the gas turbine, it is important to know the location and abrasion rate of these critical areas. The flow structure within the pre-swirl cooling air system results in locally focused abrasion regions, which are investigated in this paper. New simulations, taking additional physical effects into account, are discussed in the paper. The simulation results are compared to results obtained by measurements and observations within the test rig. Qualitative and quantitative results show the ability to predict the quantity of abrasion during operation on various critical areas of the system.

Experimental Analysis of Dust Separation in the Internal Cooling Air System of Gas Turbines

2002 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
A. W. Reichert
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
Turbine Rotor ◽  
Rotor Blades ◽  
Internal Cooling ◽  
Test Rig ◽  
Air System ◽  
And Performance ◽  
Cooling Air

For further improvements in efficiency and performance a better understanding of the internal cooling air system of gas turbines, which provides the turbine rotor blades with cooling air, is necessary. With the increase of cooling air passing through the internal air system, a greater amount of air borne particles are transported to the film cooling holes at the turbine blade surface. In spite of their small size, these holes are critical for blade cooling. Blockage of only a few holes could have harmful effects on the cooling film surrounding the blade. As a result, a reduced mean time between maintenance or even unexpected operation faults of the gas turbine during operation occurs. With a new test rig, the behaviour of particles in the internal cooling air system could be investigated at realistic flow conditions compared to a modern, real world gas turbine. It is possible to simulate different particle sizes and dust concentrations in the coolant air. A first comparison of design expectations and measurements, showing the behaviour of air borne particles in the internal cooling air system under realistic environmental conditions is given in the paper. Further the design tools for nearly a full internal air system flow path could be validated with this new test rig.

Investigations of Dust Separation in the Internal Cooling Air System of Gas Turbines

2003 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
F.-K. Benra ◽  
D. Brillert
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
Turbine Blades ◽  
Internal Cooling ◽  
Flow Conditions ◽  
Test Rig ◽  
Complex Flow ◽  
Air System ◽  
Cooling Air

Improvements in efficiency and performance of gas turbines require a better understanding of the internal cooling air system which provides the turbine blades with cooling air. With the increase of cooling air passing through the internal air system, a greater amount of air borne particles is transported to the film cooling holes at the turbine blade surface. In spite of their small size, these holes are critical for blockage. Blockage of only a few holes could have harmful effects on the cooling film surrounding the blade. As a result, a reduced mean time between maintenance or even unexpected operation faults of the gas turbine during operation could occure. Experience showed a complex interaction of cooling air under different flow conditions and its particle load. To get more familiar with all these influences and the system itself, a test rig has been built. With this test rig, the behaviour of particles in the internal cooling air system could be studied at realistic flow conditions compared to a modern, heavy duty gas turbine. It is possible to simulate different particle sizes and dust concentrations in the coolant air. The test rig has been designed to give information about the quantity of separated particles at various critical areas of the internal air system [1]. The operation of the test rig as well as analysis of particles in such a complex flow system bear many problems, addressed in the previous paper [1]. New measurements and analysis methods give new and more accurate results, which will be shown in this paper. Furthermore the inspection of the test rig shows dust deposits at unexpected positions of the flow path. Theoretical studies to characterize the flow behaviour of the disperse phase in a continuous fluid using Lagrangian Tracking were also performed. A comparison between the numerical solution and the measurements will be shown in the paper.

Trade-Off Assessments for Part Load Controlled Cooling Air in Stationary Gas Turbines

2020 ◽  
Author(s):  
Dominik Woelki ◽  
Dieter Peitsch
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Coupled Model ◽  
Life Time ◽  
Part Load ◽  
Trade Offs ◽  
Air Supply ◽  
Air System ◽  
Secondary Air ◽  
Cooling Air

Abstract The demand for flexible operation of stationary gas turbines, especially at part load, requires the simultaneous design for sufficient efficiency and life time. Both can be addressed by the secondary air system. The here applied concept modulates cooling air supply in off-design. Typically, a reduction of cooling air leads to higher efficiency but shorter turbine life time. This paper presents investigations on such concepts, aiming for trade-offs between fuel burn and turbine blade life. The considered life time mechanisms are creep, which is dominant in rotor blades, and oxidation. In addition, the effects on emissions from the combustion are outlined. The reference gas turbine is a literature-based, generic gas turbine in the 300 MWpower output segment. Regarding cooling air control, the focus is on the first two stages of the four-stage turbine. All simulations are performed by application of component zooming with an appropriate in-house tool: a previously introduced coupled model of the reference gas turbine that essentially connects gas turbine performance with a secondary air system network model. This coupled model is now extended with blade life evaluation and emission models. The results contain trade-offs for different operating points at base and part load. For example, the combined cooling air control of stage 1 rotor blade and stage 2 vane offers several benefits regarding fuel consumption: saving up to Δwfuel,rel = 0.5% in the heat recovery’s kink point operation at 60 % of base load of a combined cycle application. This saving is at the expense of creep life. However, some operating points could even operate at higher blade temperatures in order to improve life regarding hot corrosion. Furthermore, generic sensitivities of controlled secondary air supply to cooling layers and hot gas ingestion at rim seals are discussed. Overall, the presented trades mark promising potentials of modulated secondary air system concepts from a technical point of view.

Dust Separation in a Gas Turbine Pre-Swirl Cooling Air System: A Parameter Variation

2004 ◽  
Author(s):  
O. Schneider ◽  
H. J. Dohmen ◽  
F.-K. Benra ◽  
D. Brillert
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Gas Turbines ◽  
Flow Behavior ◽  
Internal Cooling ◽  
Test Rig ◽  
Swirl Generator ◽  
Air System ◽  
Heavy Duty Gas Turbine ◽  
Cooling Air

With the increase of cooling air passing through the internal air system of modern gas turbines, a greater amount of air borne particles is transported to the film cooling holes at the turbine blade surface. In spite of their small size, these holes are critical for blockage. A test rig has been designed to give information about the quantity of separated particles at various critical areas of the internal air system. With this test rig, the behavior of particles in the internal cooling air system could be studied at realistic flow conditions compared to a modern, heavy duty gas turbine. It is possible to simulate different particle sizes and dust concentrations in the coolant air. Numerical studies to characterize the flow behavior of the disperse phase in a continuous fluid using Lagrange Tracking were performed. The main influencing parameters, which are the mass flow through the system, the rotor speed and the nozzle angle of the pre-swirl generator, were varied. Furthermore to validate the theoretical studies, based on the presented variations a special point of operation was selected to get a comparable measurement, which is presented in the paper. Comparison between simulation and measurement shows additional influences of the particle shape, which were discussed. The resulting enhanced model and the comparison to the measurement is presented in the paper.

Tradeoff Assessments for Part Load Controlled Cooling Air in Stationary Gas Turbines

2020 ◽  
Vol 142 (10) ◽  
Author(s):  
Dominik Woelki ◽  
Dieter Peitsch
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Coupled Model ◽  
Combined Cycle ◽  
Controlled Cooling ◽  
Part Load ◽  
Air System ◽  
Secondary Air ◽  
Cooling Air ◽  
Operating Points

Abstract The demand for flexible part load operation of stationary gas turbines requires the simultaneous design for sufficient efficiency and lifetime. Both can be addressed by the secondary air system. This paper presents investigations on the concepts of cooling air reduction in off-design, aiming for tradeoffs between fuel burn and turbine blade life. The considered lifetime mechanisms are creep and oxidation. In addition, the effects on emissions from the combustion are outlined. The reference gas turbine is a generic gas turbine in the 300 MW power output segment. The focus is on the first two stages of the four-stage turbine. All simulations are performed by application of a coupled model that essentially connects gas turbine performance with a secondary air system network model. This coupled model is now extended with blade life evaluation and emission models. The results contain tradeoffs for operating points at base and part load. For example, the combined cooling air control of stage 1 rotor blade and stage 2 vane offers savings up to 0.5% fuel flow at 60% of base load in a combined cycle application. This saving is at the expense of creep life. However, some operating points could even operate at higher blade temperatures in order to improve life regarding hot corrosion. Furthermore, generic sensitivities of controlled secondary air supply to cooling layers and hot gas ingestion are discussed. Overall, the presented trades mark promising potentials of modulated secondary air system concepts from a technical point of view.

scholarly journals Clear Skies Ahead

2016 ◽  
Vol 138 (06) ◽  
pp. 38-43
Author(s):  
Lee S. Langston
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Power Plants ◽  
Electrical Power ◽  
Vital Role ◽  
Medium Size ◽  
Steady Increase ◽  
Innovative Design ◽  
Turbine Engine ◽  
Boom And Bust

This article discusses various fields where gas turbines can play a vital role. Building engines for commercial jetliners is the largest market segment for the gas turbine industry; however, it is far from being the only one. One 2015 military gas turbine program of note was the announcement of an U.S. Air Force competition for an innovative design of a small turbine engine, suitable for a medium-size drone aircraft. The electrical power gas turbine market experienced a sharp boom and bust from 2000 to 2002 because of the deregulation of many electric utilities. Since then, however, the electric power gas turbine market has shown a steady increase, right up to present times. Coal-fired plants now supply less than 5 percent of the electrical load, having been largely replaced by new natural gas-fired gas turbine power plants. Working in tandem with renewable energy power facilities, the new fleet of gas turbines is expected to provide reliable, on-demand electrical power at a reasonable cost.

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