Numerical modeling of co-emissions for gas turbine combustors operating at part-load conditions

Klarmann, Noah; Zoller, Benjamin Timo; Sattelmayer, Thomas

doi:10.22261/jgpps.c3n5oa

Cited by 18 publications

(11 citation statements)

References 5 publications

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“…We hence consider turbulent mixing to be the limiting mechanism and CO is described by flamelets. As shown by the authors in Klarmann et al (2018Klarmann et al ( , 2019, it is important to consider flame stretch as well as heat loss. • post-flame zone: The interface between in-and post-flame zone is defined by the point at which the turbulent time scales are not the limiting factor anymore as chemical time scales become dominating.…”

Section: Methodsmentioning

confidence: 99%

“…The idea of separating the time scales of combustion and burnout is adopted in the present work. The CO model was firstly introduced and validated in an atmospheric single-burner test rig in Klarmann et al (2018). In the following, this modeling strategy is extended to consider quenching effects that are demonstrated to play an important role in predicting CO emissions.…”

Section: Introductionmentioning

confidence: 99%

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Canonical Validation of a Modeling Strategy for Carbon Monoxide Emissions in Staged Operation of Gas Turbine Combustors

Klarmann¹,

Sattelmayer²

2020

J. Glob. Power Propuls. Soc.

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Canonical validation of a holistic modeling strategy for the prediction of CO emissions in staged operation of gas turbine combustors is subject of this study. Results from various validation cases are presented. Focus is on operating conditions that can be considered typical for modern, flexible gas turbines that meet the requirements of the upcoming new energy age. Reducing load in gas turbines is usually achieved by redistributing fuel referred to as fuel staging. Fuel-staged operation may lead to various mechanism like strong interaction of the flame with secondary air leading to quenching and elevated CO emissions and is-due to technical relevancestressed in this work. In the recent past, our group published a new modeling strategy for the precise prediction of heat release distributions as well as CO emissions. An extension to the CO modeling strategy that is of high relevance for the introduced validation cases is addressed by this work. The first part of this study presents relevant aspects of the overall modelling strategy. Furthermore, a validation of the models is shown to demonstrate the ability of precisely predicting CO in two different multi-burner cases. Both validation cases feature a silo combustion chamber with 37 burners. The burner groups are switched off at partial load leading to intense interactions between hot and cold burners. Major improvement in comparison to CO predictions from a flamelet-based combustion model can be achieved as the modeling strategy is demonstrated to be capable of predicting global CO emissions accurately. Furthermore, the model's precision in fuel staging scenarios are demonstrated and discussed.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Canonical Validation of a Modeling Strategy for Carbon Monoxide Emissions in Staged Operation of Gas Turbine Combustors

Klarmann¹,

Sattelmayer²

2020

J. Glob. Power Propuls. Soc.

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“…Numerical investigations using large-eddy simulations (LES) have shown promising results for the prediction of CO pollutants [11][12][13][14]. Studies analyzing carbon monoxide at gas turbine part load conditions have been performed by Wegner et al [15] and Klarmann et al [16], where Reynolds-averaged Navier-Stokes (RANS) simulations with a flamelet approach [17] have been performed. A progress variable was introduced to model the slow CO oxidation in the post flame region, while considering stretch effects [16].…”

Section: Introductionmentioning

confidence: 99%

“…Studies analyzing carbon monoxide at gas turbine part load conditions have been performed by Wegner et al [15] and Klarmann et al [16], where Reynolds-averaged Navier-Stokes (RANS) simulations with a flamelet approach [17] have been performed. A progress variable was introduced to model the slow CO oxidation in the post flame region, while considering stretch effects [16]. Menon [18] and Eggenspieler et al [19] investigated flames near the lean-blowout limit using LES with a flamelet approach and suggested to account for finite rate kinetics to improve predictions.…”

Section: Introductionmentioning

confidence: 99%

LES Analysis of CO Emissions from a High Pressure Siemens Gas Turbine Prototype Combustor at Part Load

et al. 2020

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This work contributes to the understanding of mechanisms that lead to increased carbon monoxide (CO) concentrations in gas turbine combustion systems. Large-eddy simulations (LES) of a full scale high pressure prototype Siemens gas turbine combustor at three staged part load operating conditions are presented, demonstrating the ability to predict carbon monoxide pollutants from a complex technical system by investigating sources of incomplete CO oxidation. Analytically reduced chemistry is applied for the accurate pollutant prediction together with the dynamic thickened flame model. LES results show that carbon monoxide emissions at the probe location are predicted in good agreement with the available test data, indicating two operating points with moderate pollutant levels and one operating point with CO concentrations below 10 ppm. Large mixture inhomogeneities are identified in the combustion chamber for all operating points. The investigation of mixture formation indicates that fuel-rich mixtures mainly emerge from the pilot stage resulting in high equivalence ratio streaks that lead to large CO levels at the combustor outlet. Flame quenching due to flame-wall-interaction are found to be of no relevance for CO in the investigated combustion chamber. Post-processing with Lagrangian tracer particles shows that cold air—from effusion cooling or stages that are not being supplied with fuel—lead to significant flame quenching, as mixtures are shifted to leaner equivalence ratios and the oxidation of CO is inhibited.

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“…Bainier et al 8 recently reported their progress on the development of such a predictive emission monitoring system, which however requires recalibration every quarter of the year. In contrast, physical models such as reactor networks 2,9 and CFD simulations [10][11][12] are able to predict spatially resolved CO formation and thus allow for detailed physical investigation of combustor design and operation aspects. The accuracy and success of these methods are highly dependent on the existence and quality of boundary conditions, such as oxidant and fuel composition and flow, temperature, pressure, and detailed geometry.…”

Section: Introductionmentioning

confidence: 99%

Long-term carbon monoxide emission behavior of heavy-duty gas turbines: An approach for model-based monitoring and diagnostics

Lipperheide

Gassner²,

Weinmann

et al. 2018

International Journal of Spray and Combustion Dynamics

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Emission measurements are a valuable source of information regarding the condition of gas turbine combustors. Aging of the hot gas path components can lead to an emission increase, which may ultimately require a readjustment of operational settings and accordingly impacts plant availability and maintenance. While NOx emissions may become crucial in high flame temperatures at full load, carbon monoxide emissions typically restrict low-load operation, which electricity markets demand more frequently due to the increasing penetration of intermittent renewable power. This paper presents a semiempirical carbon monoxide model that allows for quantifying the evolution of carbon monoxide emissions for GT24/GT26 heavy-duty gas turbines in commercial long-term operation. Input parameters to the derived carbon monoxide model are either directly measured or reconstructed by virtual measurements based on a simplified engine model. The method is developed with commissioning and operation data of three different gas turbines of GE’s GT24/GT26 fleet and validated over a total of 8.5 years of observation. Aging is accounted for by incorporating control sensor deviation and the formation of cold spots in the combustor into the semiempirical model. When these effects are taken into account, the carbon monoxide prediction is improved by up to 60% in terms of root mean square error of the log10(carbon monoxide) values compared to a benchmark case without consideration of aging.

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Numerical modeling of co-emissions for gas turbine combustors operating at part-load conditions

Cited by 18 publications

References 5 publications

Canonical Validation of a Modeling Strategy for Carbon Monoxide Emissions in Staged Operation of Gas Turbine Combustors

Canonical Validation of a Modeling Strategy for Carbon Monoxide Emissions in Staged Operation of Gas Turbine Combustors

LES Analysis of CO Emissions from a High Pressure Siemens Gas Turbine Prototype Combustor at Part Load

Long-term carbon monoxide emission behavior of heavy-duty gas turbines: An approach for model-based monitoring and diagnostics

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