Combustion Oscillation Monitoring Using Flame Ionization in a Turbulent Premixed Combustor

2006 ◽  
Vol 129 (2) ◽  
pp. 352-357 ◽  
Author(s):  
B. T. Chorpening ◽  
J. D. Thornton ◽  
E. D. Huckaby ◽  
K. J. Benson
Keyword(s):  
Standard Deviation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Dynamic Pressure ◽  
Pressure Oscillation ◽  
Chamber Pressure ◽  
Ion Distribution ◽  
Combustion Dynamics ◽  
Gas Turbine Combustors ◽  
Flame Ionization

To achieve very low NOx emission levels, lean-premixed gas turbine combustors have been commercially implemented that operate near the fuel-lean flame extinction limit. Near the lean limit, however, flashback, lean blow off, and combustion dynamics have appeared as problems during operation. To help address these operational problems, a combustion control and diagnostics sensor (CCADS) for gas turbine combustors is being developed. CCADS uses the electrical properties of the flame to detect key events and monitor critical operating parameters within the combustor. Previous development efforts have shown the capability of CCADS to monitor flashback and equivalence ratio. Recent work has focused on detecting and measuring combustion instabilities. A highly instrumented atmospheric combustor has been used to measure the pressure oscillations in the combustor, the OH emission, and the flame ion field at the premix injector outlet and along the walls of the combustor. This instrumentation allows examination of the downstream extent of the combustion field using both the OH emission and the corresponding electron and ion distribution near the walls of the combustor. In most cases, the strongest pressure oscillation dominates the frequency behavior of the OH emission and the flame ion signals. Using this highly instrumented combustor, tests were run over a matrix of equivalence ratios from 0.6 to 0.8, with an inlet reference velocity of 25m∕s(82ft∕s). The acoustics of the fuel system for the combustor were tuned using an active-passive technique with an adjustable quarter-wave resonator. Although several statistics were investigated for correlation with the dynamic pressure in the combustor, the best correlation was found with the standard deviation of the guard current. The data show a monotonic relationship between the standard deviation of the guard current (the current through the flame at the premix injector outlet) and the standard deviation of the chamber pressure. Therefore, the relationship between the standard deviation of the guard current and the standard deviation of the pressure is the most promising for monitoring the dynamic pressure of the combustor using the flame ionization signal. This addition to the capabilities of CCADS would allow for dynamic pressure monitoring on commercial gas turbines without a pressure transducer.

Combustion Oscillation Monitoring Using Flame Ionization in a Turbulent Premixed Combustor

2004 ◽  
Author(s):  
B. T. Chorpening ◽  
J. D. Thornton ◽  
E. D. Huckaby ◽  
K. J. Benson
Keyword(s):  
Standard Deviation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Dynamic Pressure ◽  
Pressure Oscillation ◽  
Chamber Pressure ◽  
Ion Distribution ◽  
Combustion Dynamics ◽  
Gas Turbine Combustors ◽  
Flame Ionization

To achieve very low NOx emission levels, lean-premixed gas turbine combustors have been commercially implemented which operate near the fuel-lean flame extinction limit. Near the lean limit, however, flashback, lean blowoff, and combustion dynamics have appeared as problems during operation. To help address these operational problems, a combustion control and diagnostics sensor (CCADS) for gas turbine combustors is being developed. CCADS uses the electrical properties of the flame to detect key events and monitor critical operating parameters within the combustor. Previous development efforts have shown the capability of CCADS to monitor flashback and equivalence ratio. Recent work has focused on detecting and measuring combustion instabilities. A highly instrumented atmospheric combustor has been used to measure the pressure oscillations in the combustor, the OH emission, and the flame ion field at the premix injector outlet and along the walls of the combustor. This instrumentation allows examination of the downstream extent of the combustion field using both the OH emission and the corresponding electron and ion distribution near the walls of the combustor. In most cases, the strongest pressure oscillation dominates the frequency behavior of the OH emission and the flame ion signals. Using this highly instrumented combustor, tests were run over a matrix of equivalence ratios from 0.6 to 0.8, with an inlet reference velocity of 25 m/s. The acoustics of the fuel system for the combustor were tuned using an active-passive technique with an adjustable quarter-wave resonator. Although several statistics were investigated for correlation with the dynamic pressure in the combustor, the best correlation was found with the standard deviation of the guard current. The data show a monotonic relationship between the standard deviation of the guard current (the current through the flame at the premix injector outlet) and the standard deviation of the chamber pressure. Therefore, the relationship between the standard deviation of the guard current and the standard deviation of the pressure is the most promising for monitoring the dynamic pressure of the combustor using the flame ionization signal. This addition to the capabilities of CCADS would allow for dynamic pressure monitoring on commercial gas turbines without a pressure transducer.

Flame Ionization Distribution and Dynamics Monitoring in a Turbulent Premixed Combustor

2006 ◽  
Author(s):  
B. T. Chorpening ◽  
E. D. Huckaby ◽  
M. L. Morris ◽  
J. D. Thornton ◽  
K. J. Benson
Keyword(s):  
Standard Deviation ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Control Technique ◽  
Operating Parameters ◽  
Pressure Oscillations ◽  
Combustion Dynamics ◽  
Gas Turbine Combustors ◽  
Flame Ionization ◽  
Flame Emission

To achieve very low NOx emission levels, lean-premixed gas turbine combustors have been commercially implemented which operate near the fuel-lean flame extinction limit. Near the lean limit, however, flashback, lean blowoff, and combustion dynamics have appeared as problems during operation. To help address these operational problems, a combustion control and diagnostics sensor (CCADS) for gas turbine combustors is being developed. CCADS uses the electrical properties of the flame to detect key events and monitor critical operating parameters within the combustor. Previous development efforts have shown the capability of CCADS to monitor flashback and equivalence ratio, and progress has been made on detecting and measuring combustion instabilities. In support of this development, a highly instrumented atmospheric combustor has been used to measure the pressure oscillations in the combustor, the ultraviolet flame emission, and the flame ion field at the premix injector outlet and along the walls of the combustor. This instrumentation allows examination of the downstream extent of the combustion field using both the ultraviolet (mostly OH*) emission and the corresponding electron and ion distribution near the walls of the combustor. During testing the combustion dynamics were controlled using a fuel feed impedance control technique. This provided flame ionization measurements for both steady and unsteady combustion, without changing the operating parameters of the combustor. Previous testing in this combustor had fewer data acquisition channels, and did not include a full implementation of a CCADS centerbody. This testing included both the guard and sense CCADS electrodes installed on the nozzle centerbody, and an array of 14 wall mounted spark plugs to monitor the flame ionization downstream along the walls of the combustor. This paper reports the results of this testing, focusing on the relationship between the flame ionization, ultraviolet flame emission, and pressure oscillations. Tests were run over a matrix of equivalence ratios from 0.6 to 0.8, with inlet reference velocities of 20 and 25 m/s. The acoustics of the fuel system for the combustor were tuned using an active-passive technique with an adjustable quarter-wave resonator. Data processing included computing the logarithm of the real-time current signal from the guard electrode, to compensate for the exponential decay of the potential field from the electrode. The data show the standard deviation of the guard current to be the most promising statistic investigated for correlation with the standard deviation of the chamber pressure. This correlation could expand the capabilities of CCADS to allow for dynamic pressure monitoring on commercial gas turbines without a pressure transducer.

Modeling and Control of Combustion Dynamics in Industrial Gas Turbines

2004 ◽  
Author(s):  
Keith McManus ◽  
Fei Han ◽  
Wayne Dunstan ◽  
Corneliu Barbu ◽  
Minesh Shah
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Pressure Oscillation ◽  
Fast Response ◽  
Operating Conditions ◽  
Fuel System ◽  
Combustion Dynamics ◽  
Modeling And Control ◽  
Persistent Excitation ◽  
Industrial Gas Turbines

The thermoacoustic response of an industrial-scale gas turbine combustor to fuel flow perturbations is examined. Experimental measurements in a laboratory combustor along with numerical modeling results are used to identify the dynamic behavior of the combustor over a variety of operating conditions. A fast-response actuator was coupled to the fuel system to apply continuous sinusoidal perturbations to the total fuel mass flow rate. The effects of these perturbations on the combustor pressure oscillation characteristics as well as overall operability of the system are described. The results of this work suggest that persistent excitation of the fuel system may present a viable means of controlling combustion dynamics in industrial gas turbine and, in turn, enhance their performance.

scholarly journals Thermoacoustic Instability Considerations for High Hydrogen Combustion in Lean Premixed Gas Turbine Combustors: A Review

Hydrogen ◽  
2021 ◽  
Vol 2 (1) ◽  
pp. 33-57
Author(s):  
Jadeed Beita ◽  
Midhat Talibi ◽  
Suresh Sadasivuni ◽  
Ramanarayanan Balachandran
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Hydrogen Combustion ◽  
Dynamic State ◽  
Pure Hydrogen ◽  
High Hydrogen ◽  
Combustion Dynamics ◽  
Thermoacoustic Instability ◽  
Gas Turbine Combustors ◽  
Lean Premixed

Hydrogen is receiving increasing attention as a versatile energy vector to help accelerate the transition to a decarbonised energy future. Gas turbines will continue to play a critical role in providing grid stability and resilience in future low-carbon power systems; however, it is recognised that this role is contingent upon achieving increased thermal efficiencies and the ability to operate on carbon-neutral fuels such as hydrogen. An important consideration in the development of gas turbine combustors capable of operating with pure hydrogen or hydrogen-enriched natural gas are the significant changes in thermoacoustic instability characteristics associated with burning these fuels. This article provides a review of the effects of burning hydrogen on combustion dynamics with focus on swirl-stabilised lean-premixed combustors. Experimental and numerical evidence suggests hydrogen can have either a stabilising or destabilising impact on the dynamic state of a combustor through its influence particularly on flame structure and flame position. Other operational considerations such as the effect of elevated pressure and piloting on combustion dynamics as well as recent developments in micromix burner technology for 100% hydrogen combustion have also been discussed. The insights provided in this review will aid the development of instability mitigation strategies for high hydrogen combustion.

Modeling Unsteady Flow of a Lean Partially Premixed Flame on a Dry Low NOx Combustion System

2013 ◽  
Author(s):  
Salvatore Matarazzo ◽  
Hannes Laget ◽  
Evert Vanderhaegen ◽  
Jim B. W. Kok
Keyword(s):  
Gas Turbine ◽  
Limit Cycle ◽  
Gas Turbines ◽  
Premixed Flame ◽  
Computational Domain ◽  
Pressure Oscillations ◽  
Combustion Dynamics ◽  
Partially Premixed ◽  
Partially Premixed Flame ◽  
Limit Cycle Behavior

The phenomenon of combustion dynamics (CD) is one of the most important operational challenges facing the gas turbine (GT) industry today. The Limousine project, a Marie Curie Initial Training network funded by the European Commission, focuses on the understanding of the limit cycle behavior of unstable pressure oscillations in gas turbines, and on the resulting mechanical vibrations and materials fatigue. In the framework of this project, a full transient CFD analysis for a Dry Low NOx combustor in a heavy duty gas turbine has been performed. The goal is to gain insight on the thermo-acoustic instability development mechanisms and limit cycle oscillations. The possibility to use numerical codes for complex industrial cases involving fuel staging, fluid-structure interaction, fuel quality variation and flexible operations has been also addressed. The unsteady U-RANS approach used to describe the high-swirled lean partially premixed flame is presented and the results on the flow characteristics as vortex core generation, vortex shedding, flame pulsation are commented on with respect to monitored parameters during operations of the GT units at Electrabel/GDF-SUEZ sites. The time domain pressure oscillations show limit cycle behavior. By means of Fourier analysis, the coupling frequencies caused by the thermo-acoustic feedback between the acoustic resonances of the chamber and the flame heat release has been detected. The possibility to reduce the computational domain to speed up computations, as done in other works in literature, has been investigated.

New Catalytic Combustion Technology for Very Low Emissions Gas Turbines

1994 ◽  
Author(s):  
R. A. Dalla Betta ◽  
J. C. Schlatter ◽  
S. G. Nickolas ◽  
D. K. Yee ◽  
T. Shoji
Keyword(s):  
Thermal Shock ◽  
Gas Turbine ◽  
High Temperatures ◽  
Gas Turbines ◽  
Catalytic Combustion ◽  
Combustion Process ◽  
Combustion System ◽  
Gas Turbine Combustors ◽  
Homogeneous Combustion ◽  
Combustion Technology

A catalytic combustion system has been developed which feeds full fuel and air to the catalyst but avoids exposure of the catalyst to the high temperatures responsible for deactivation and thermal shock fracture of the supporting substrate. The combustion process is initiated by the catalyst and is completed by homogeneous combustion in the post catalyst region where the highest temperatures are obtained. This has been demonstrated in subscale test rigs at pressures up to 14 atmospheres and temperatures above 1300°C (2370°F). At pressures and gas linear velocities typical of gas turbine combustors, the measured emissions from the catalytic combustion system are NOx < 1 ppm, CO < 2 ppm and UHC < 2 ppm, demonstrating the capability to achieve ultra low NOx and at the same time low CO and UHC.

scholarly journals Flame Ionization Sensor Integrated Into a Gas Turbine Fuel Nozzle

2005 ◽  
Vol 127 (1) ◽  
pp. 42-48 ◽  
Author(s):  
Kelly Benson ◽  
Jimmy D. Thornton ◽  
Douglas L. Straub ◽  
E. David Huckaby ◽  
Geo. A. Richards
Keyword(s):  
Gas Turbine ◽  
Low Cost ◽  
Stability Margin ◽  
Thermodynamic Efficiency ◽  
Flame Stability ◽  
Fuel Quality ◽  
Widespread Application ◽  
Combustion Dynamics ◽  
Flame Ionization ◽  
Fuel Nozzle

Recent advances in lean premix gas turbine combustion have focused primarily on increasing thermodynamic efficiency, reducing emissions, and minimizing combustion dynamics. The practical limitation on increasing efficiency at lower emissions is the onset of combustion instability, which is known to occur near the lean flammability limit. In a laboratory environment there are many sensors available that provide the combustion engineer with adequate information about flame stability, but those sensors are generally too expensive or unreliable for widespread application in the field. As a consequence, engines must be commissioned in the field with adequate stability margin such that normally expected component wear, fuel quality, and environmental conditions will not cause the turbine to experience unstable combustion. Woodward Industrial Controls, in cooperation with the National Energy Technology Laboratory, is developing a novel combustion sensor that is integrated into the fuel nozzle such that low cost and long life are achieved. The sensor monitors flame ionization, which is indicative of air–fuel ratio and most importantly flame stability.

Readings on Specific Gas Turbine Flame Behaviours Using an Industrial Combustion Monitoring System

2016 ◽  
Author(s):  
Fabrice Giuliani ◽  
Hans Reiss ◽  
Markus Stuetz ◽  
Vanessa Moosbrugger ◽  
Alexander Silbergasser
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Dynamic Pressure ◽  
Pressure Sensors ◽  
Research Programme ◽  
Response Measurement ◽  
Efficient Operation ◽  
Maintenance Costs ◽  
Full Field ◽  
Combustion Monitoring

The new energy mix places greater demands on power gas turbine operation; precision combustion monitoring, therefore has become a major issue. Unforeseen events such as combustion instabilities can occur and represent a danger to the integrity of the hot parts and also lead to a limitation of the output power. This is usually accompanied by an increase in maintenance costs. The enlarged off-design operating envelope of gas turbines to adapt to a fast-changing grid has made this issue even more acute, necessitating an expansion of the operating envelope into areas that were — for many engines — not foreseen in the original combustor design process. A good understanding of what happens within the gas turbine combustor is crucial. Complex and costly full-field measurements such as laboratory optical instrumentation in precision combustion diagnostics are not suitable for permanent fleet deployment. For practical and financial reasons, the monitoring should ideally be achieved with a limited amount of discrete sensors. If installed and interpreted correctly, fast response measurement chains could lead to a better gas turbine combustion management, possibly yielding considerable savings in terms of operating and maintenance costs. The firm Meggitt Sensing System (MSS), assisted by Combustion Bay One (CBOne), initiated an applied research programme dedicated to this topic — with MSS providing the instrumentation and CBOne providing the facility and test conditions. The objective was to investigate realistic combustion phenomena in a precisely controlled and reproducible way and to document the individual readings of the heat-resistant fast pressure transducers mounted on the combustor casing, as well as the accelerometers mounted on the outer surface of the machine. Particular attention was paid to the correlation between these two types of sensor readings. This paper reports on the monitoring of the flame using piezoelectric dynamic pressure sensors and accelerometers in a number of different situations that are relevant to the safe and efficient operation of gas turbines. Discussed are single events such as flame ignition, lean blow-out and flash-back, as well as longer test sequences observing the effect of warming-up or the presence of flame instability. The measurement chains and processing techniques are discussed in detail. The atmospheric test rig used for this purpose and the different testing configurations required for each of these situations are also illustrated in detail. The results and recommendations for their implementation in an industrial context conclude this paper.

scholarly journals Design and Test of a New Axial Compressor for the Nuovo Pignone Heavy Duty Gas Turbines

1996 ◽  
Author(s):  
Erio Benvenuti
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Dynamic Pressure ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Leading Edge ◽  
Meridional Flow ◽  
Heavy Duty ◽  
Pressure Transducers ◽  
Easy Integration

This axial compressor design was primarily focused to increase the power rating of the current Nuovo Pignone PGT10 Heavy-Duty gas turbine by 10%. In addition, the new 11-stage design favourably compares with the existing 17-stage compressor in terms of simplicity and cost. By seating the flowpath and blade geometry, the new aerodynamic design can be applied to gas turbines with different power ratings as well. The reduction in the stage number was achieved primarily through the meridional flow-path redesign. The resulting higher blade peripheral speeds achieve larger stage pressure ratios without increasing the aerodynamic loadings. Wide chord blades keep the overall length unchanged thus assuring easy integration with other existing components. The compressor performance map was extensively checked over the speed range required for two-shaft gas turbines. The prototype unit was installed on a special PGT10 gas turbine setup, that permitted the control of pressure ratio independently from the turbine matching requirements. The flowpath instrumentation included strain-gages, dynamic pressure transducers and stator vane leading edge aerodynamic probes to determine individual stage characteristics. The general blading vibratory behavior was proved fully satisfactory. With minor adjustments to the variable stator settings the front stage aerodynamic matching was optimized and the design performance was achieved.

Digital Solutions for Power Plant Operators in a Dynamic Market Place: An Advanced Automated Gas Turbine Combustion Tuning for Low Emissions and Operational Flexibility

2019 ◽  
Author(s):  
Nicolas Demougeot ◽  
Alexander Steinbrenner ◽  
Wenping Wang ◽  
Matt Yaquinto
Keyword(s):  
Power Systems ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Service Providers ◽  
System Development ◽  
Engine Performance ◽  
Operational Flexibility ◽  
Ambient Conditions ◽  
Market Place ◽  
Combustion Dynamics

Abstract Since the advent of premix combustion technology in industrial gas turbines, regular manual combustion tuning and engine adjustments have been necessary to maintain engines within emission regulatory limits and to control combustion dynamics (pulsations) for hardware integrity. The emissions and pulsation signatures of premix combustors are strongly driven by ambient conditions, engine performance, degradation and fuel composition. As emissions limits became more stringent over the years, higher combustion dynamics were encountered and challenges to maintain acceptable settings after yearly combustion inspections were regularly encountered. This challenge was further increased as sites operating advanced Gas Turbines (GT) eliminated Combustion Inspections (CI) and required uninterrupted generation at optimum settings for up to three years. The case for automated tuning systems became evident for the Industrial Gas Turbine (IGT) market in the mid 2000’s and different IGT manufacturers and service providers began developing them. Power Systems Manufacturing (PSM) developed the AutoTune (AT) system in 2008 and has since installed it in over fifty units, accumulating close to a million hours of operation. The history of PSM’s AT system development as well as a description of its fundamental principles and capabilities are discussed. The power generation market is changing rapidly with the injection of renewables, thus driving the demand for operational flexibility, the design of PSM’s multi-platform compatible, AutoTune system; allowing for increased peak power, extended turndown and transient tuning is discussed. The paper also describes, how, using the same tuning principles, the application for an AutoTune system can be extended to the Balance Of Plant (BOP) equipment.

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