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Mannheim, Germany

Bade S.,TU Munich | Wagner M.,TU Munich | Hirsch C.,TU Munich | Sattelmayer T.,TU Munich | Schuermans B.,Aistom Power Service GmbH
Proceedings of the ASME Turbo Expo

A Design for Thermo-Acoustic Stability (DeTAS) procedure is presented, that aims at selecting a most stable burner geometry for a given combustor. It is based on the premise that a thermo-acoustic stability model of the combustor can be formulated and that a burner design exists, which has geometric design parameters that sufficiently influence the dynamics of the flame. Describing the burner and flame dynamics in dependence of the geometrical parameters an optimization procedure involving a linear stability model of the target combustor maximizes the damping and thereby yields the optimal geometrical parameters. To demonstrate the procedure on an existing annular combustor a generic burner design was developed that features two geometrical parameters that can easily be adjusted. To provide the data base for the DeTAS procedure static and dynamical properties of burner and flame were measured for three by three configurations at a fixed operation point. The data is presented and discussed. It is found that the chosen design exhibits a significant variability of the flame dynamics in dependence of the geometrical parameters indicating that a DeTAS should be possible for the targeted annular combustor. Copyright © 2013 by Alstom Technology. Source

Seidel V.,TU Munich | Marosky A.,TU Munich | Hirsch C.,TU Munich | Sattelmayer T.,TU Munich | And 2 more authors.
Proceedings of the ASME Turbo Expo

This work presents a study of the effect of the inflow condition on the flame flashback performance of a gas turbine burner. A generic swirl burner for basic combustion research on engine scale is investigated both under atmospheric conditions in a combustion test rig and numerically to reveal the impact of inflow conditions on the burner stability. Flashback resistance is examined with highly reactive hydrogen fuel and numerical studies with isothermal large eddy simulations (LES) are performed to investigate transient flow field data. Earlier publications showed excellent flashback resistance of a down scaled burner version of similar design, which was tested in a rig with strongly restricted cross sectional inflow area. An influence of the test rig setup on the flashback limits was not expected. However, the results presented in the paper reveal that the inflow conditions at the swirler and the distribution of axial velocity inside the swirler are crucial for flame stability. The inflow conditions upstream of the swirler were modified to redistribute the axial velocity field inside the swirler. Velocity fluctuations both inside the swirler and downstream of the burner outlet were reduced and consequently the susceptibility to perturbations in the flow field. This measure prevents the formation and propagation of local zones of negative axial velocity upstream of the flame position and increases the robustness of the flow field. After modification of the inflow condition the excellent flashback limit data of the down scaled burner was fully reproduced. Copyright © 2013 by ASME and Alstom Technology. Source

Seidel V.,TU Munich | Marosky A.,TU Munich | Sattelmayer T.,TU Munich | Geng W.,Aistom Power Service GmbH | Magni F.,Aistom Power Service GmbH
Proceedings of the ASME Turbo Expo

Lean blow out (LBO) has a big impact on emission formation at part load of gas turbines, where flame temperature is low and flame stabilization is an issue. With improved combustion behavior at LBO conditions the operation flexibility of a silo gas turbine can be increased within the scope of retrofitting. Ln multi burner arrangements a part of the preheated air designated for combustion is used for impingement cooling of the burner front panel and subsequently injected into the primary combustion zone. Ln this region of flame stabilization air and unburned fuel as well as burned products are mixed to sustain stable combustion. The object of this study is to determine the level of dilution of the flow field by the cooling air with the focus on the conditions below LBO that can impair flame stability. The question addressed in this paper is how mixing of the front panel cooling air with the incoming reactants and the combustion products in multi burner arrangements can be computed in a numerically efficient way. As test case for the methodology the local distribution of cooling air in a silo combustor is presented. Ln this numerical study mixing processes of air-fuel mixture and cooling air as well as aerodynamic interaction of adjacent burners in a multi burner systems are investigated using isothermal Reynolds Averaged Navier Stokes (RANS) simulations. Former published single burner water channel experiments and Large Eddy Simulations (LES) [1] serve as a baseline. Single burner RANS simulations are done and compared to measurement and LES to validate the velocity and scalar fields. A Schmidt number variation is used to modify the mixing process in the RANS single burner calculations. Based on the LES the single burner is modified to address the multi burner conditions and calculated with LES and RANS. Finally the multi burner system is computed with the settings applied in the single burner configuration. Using the symmetry of the investigated burner matrix an efficient methodology is implemented that allows computation of one sixth of a silo combustor. The results expose a strong burner-burner interaction of the recirculation zones and in contrast to the single burner configuration regions of concentrated cooling air. Copyright © 2013 by ASME and Alstom Technology. Source

Marosky A.,TU Munich | Seidel V.,TU Munich | Sattelmayer T.,TU Munich | Magni F.,Aistom Power Service GmbH | Geng W.,Aistom Power Service GmbH
Proceedings of the ASME Turbo Expo

In most dry low NOx combustor designs of stationary gas turbines the front panel impingement cooling air is directly injected into the combustor primary zone. This air partially mixes with the swirling flow ofpremixed reactants from the burner and reduces the effective equivalence ratio in the flame. However, local unmixedness and the lean equivalence ratio are supposed to have a major impact on combustion performance. Overall goal of this investigation is to answer the question whether the cooling air injection into the primary combustor zone has a beneficial effect on combustion stability and NOx emissions or not. The flame stabilization of a typical swirl burner with and without front panel cooling air injection is studied in detail under atmospheric conditions close to the lean blowout limit (LBO) in a full scale single burner combustion test rig. Based on previous isothermal investigations a typical injection configuration is implemented for the combustion tests. Isothermal results of experimental studies in a water test rig adopting high speed planar laser-induced fluorescence (HSPLIF) reveal the spatial and temporal mixing characteristics for the experimental setup studied under atmospheric combustion. This paper focuses on the effects of cooling air injection on both flame dynamics and emissions in the reacting case. To reveal dependencies of cooling air injection on combustion stability and NOx emissions, the amount of injected cooling air is varied. OH* -chemiluminescence measurements are applied to characterize the impact of cooling air injection on the flame front. Emissions are collected for different cooling air concentrations, both global measurements at the chamber exit and local measurements in the region of the flame front close to the burner exit. The effect of cooling air injection on pulsation level is investigated by evaluating the dynamic pressure in the combustor. The flame stabilization at the burner exit changes with an increasing degree of dilution with cooling air. Depending on the amount of cooling only a specific share of the additional air participates in the combustion process. Copyright © 2013 by ASME and Alstom Technology. Source

Rodriguez S.,Aistom Power Service GmbH | Schwevers H.,Aistom Power Service GmbH | Leidich F.-U.,Aistom Power Service GmbH | Gabrielli F.,Alstom
VGB PowerTech

New components for power plants need protection against negative environmental impact for the time between manufacturing and commissioning. This applies as well for vendor parts of machines and equipment delivered by sub-suppliers and probably intermediate storage time and transportion. The action taken is necessary to preserve the value of the components, the securing of proper functioning and warranted characteristics (for example efficiency) of the components and parts. Organic preservation chemicals are used for new power plant equipment for the time between manufacture and commissioning, thus for transport and storage. This report will give an overview of organic preservation chemicals' application, their advantages and disadvantages compared to other methods. It goes into detail for volatile products and preservation oils. Own studies allow precise differentiation of their characteristics, their effect on different materials to be protected and the impact of these chemicals or their decomposition products on the later operation. Source

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