bluuebunny/crossref_metadata_2025_split huggingface dataset:
Catalytic Partial Oxidation of Natural Gas in Gas Turbine Applications
Authors: Manrique Carrera Arturo , Jayasuriya Jeevan , Fransson Torsten 
Published: November 2013

The demands of emissions, combustion efficiency over a wider operational range, and fuel flexibility for industrial gas turbine applications are expected to increase in the coming years. Currently, it is common the use of a stabilizing piloting diffusion flame during part load operation, this flame is accountable for an important part of the thermal NOx emissions on partial load, and in some cases also at full load operation. On the other hand Catalytic Partial Oxidation (CPO) of natural gas is a technique used in petrochemical industry for the Fischer-Tropsch process and for H2 production, and is based in the production of Syn-Gas rich in H2 and CO.
The present work explores the possibility to use the CPO of natural gas in industrial gas turbine applications, it is based in experiments performed between 5 and 13 bar using an arrangement of Rh based catalyst and CH4. The experiments were done at the Catalytic Combustion High Pressure Test Facility, at the Royal Institute of Technology (KTH) in Sweden. The gas produced leaves the CPO reactor between 700 and 850 °C and it is rich in H2 and CO. It was found that the most important parameter after reaching the light off temperature in the CPO reactor is the equivalence ratio Φ, which evidences the kinetically controlled regime in the Rh catalyst that depends on O2 availability. The H2/CO ratio is close to the theoretical value of 2 and the selectivity towards H2 and CO are 90% and 95% respectively while the CH4 conversion reached approximately 55%.
Pressure on the other hand had a small negative influence in the tested pressure range and it is more relevant at richer fuel conditions (high equivalence ratios). The CPO process had shown that it is relatively easy to control the operation temperature of the catalyst. This temperature is kept below the maximum allowed by reducing the O2 availability.
The high temperature Syn-Gas gas produced through CPO process could be burnt in the downstream of the catalysts steadily at flame temperatures below the thermal-NOx threshold. The CPO reactor could provide the flame stabilization function at a wide range of operational conditions, and replace the diffusion piloting flame. This approach could cope with NOx and CO emissions in a wider operational range and offers the possibility of using different fuels as the reaction controlling factor is O2 availability. Furthermore, an initial design of a possible combustion strategy downstream of the CPO reactor is also presented.
Aerodynamic Effects of Non-Uniform Surface Roughness on a Turbine Blade
Authors: Hohenstein Sebastian , Aschenbruck Jens , Seume Joerg 
Published: November 2013

The effect on non-uniform surface roughness on the aerodynamics of a turbine blade is investigated. Surface roughness on airfoils has a significant impact on total energy loss due to skin friction and typically leads to an increased thermal loading. In the present research project, investigations are supposed to be carried out experimentally. For this a blade must be designed, which accommodates the contradictory requirements of aerodynamics and manufacturing the sections of surface roughness. A fully automatic design process based on a genetic algorithm is developed and results are shown. The designed blade sufficiently fulfills the given requirements.
A numerical study, using a low-Reynolds approach, is performed to investigate the influence of non-uniform roughness applied to different positions on the suction side of a high pressure turbine blade. It is shown that roughness applied at the leading and trailing edge does not significantly influence the flow whereas roughness at 20% cord length and at midchord induce transition. Especially surface roughness at 20% chord length shows a strong correlation to the change of total pressure loss.
Development of GT24 and GT26 (Upgrades 2011) Reheat Combustors, Achieving Reduced Emissions and Increased Fuel Flexibility
Authors: Düsing K. Michael , Ciani Andrea , Benz Urs , Eroglu Adnan , Knapp Klaus 
Published: November 2013

The recent development of the Alstom’s sequential combustion system for the GT24 (60Hz) and GT26 (50Hz) upgrades 2011 is a perfect example of evolutionary design optimizations. Better overall performance is achieved through improved SEV burner aerodynamics and fuel injection, while keeping the main features of the sequential burner technology. In particular this results in further reduced NOx and CO emissions over widest possible load range and allows operation with fuel gases with up to 18% of higher hydrocarbons (C2+) or a low Wobbe index.
An extensive validation of the new sequential burners for GT24 and GT26 has been conducted, with a wide range of validation tools. This has included high pressure sector rig testing and full-engine tests at the Alstom Power Plant Birr, Switzerland.
This paper presents the development and validation process, in terms of evolutionary design modifications and successful burner scaling, of the GT24 and GT26 (upgrades 2011) reheat combustors from concept phase to engine validation.
Evaluation of Global Mechanisms for LES Analysis of SGT-100 DLE Combustion System
Authors: Abou-Taouk Abdallah , Sadasivuni Suresh , Lörstad Daniel , Eriksson Lars-Erik 
Published: November 2013

This paper presents the results of Computational Fluid Dynamics (CFD) analyses obtained for the experimental version of the SGT-100 Dry Low Emission (DLE) gas turbine burner provided by Siemens Industrial Turbomachinery Ltd (SIT). A testing and measurement campaign for this burner was previously carried out at the DLR Institute of Combustion Technology, Stuttgart, Germany, for various operating pressure conditions. The present work shows the successful validation of the CFD model in terms of time-averaged temperature and velocity data within measurement errors at an operating pressure of 3 bar.
Several well known global mechanisms are tested in this work, namely the Westbrook Dryer 2-step (WD) scheme, the Jones and Lindstedt 4-step (JL4) scheme, the Meredith et al. 3-step (M3) scheme and a recently developed in-house 4-step scheme (M4) for methane-air mixtures. The M4 scheme is optimized by matching the detailed GRI-Mech 3.0 mechanism in terms of 1D laminar flame speed, using the CHEMKIN software for a wide range of pressures (1 to 6 bar), unburned gas temperatures (295 to 650 K) and equivalence ratios range (0.4 to 1.6).
CFD simulations are performed using the Eddy Dissipation Model (EDM)/Finite Rate Chemistry (FRC) non-premixed turbulence chemistry interaction model. Both steady-state Reynolds Averaged Navier Stokes (RANS) and hybrid Unsteady Reynolds Averaged Navier Stokes /Large Eddy Simulation (URANS/LES) turbulence models are used. The LES Wall Adaptive Large Eddy-Viscosity (WALE) model with finite rate chemistry is also tested for validation.
Velocity profiles, flame temperatures and major species are compared with experiments for different global reaction mechanisms used with different turbulence models. A reasonable agreement is found with the M4 global reaction mechanism in predicting mixing, temperatures and major species.
RANS simulations are observed to underpredict the temperature profiles downstream and overpredict in the upstream region, while the velocity profiles are found to be in close agreement with experiments. The SAS-SST turbulence model predicts the velocity profiles in good agreement with experimental data and slightly better than the RANS model. Both the transient simulations slightly overpredict the temperature profiles. The LES-WALE model gives too high and unrealistic temperatures.
Improvement of Conventional Seals for Stator-Rotor Cavities of Heavy-Duty Gas Turbines by Application of Interstage Brush-Seals
Authors: Mantero Marco , Vinci Alessandro , Bozzi Luca , D’Angelo Enrico 
Published: November 2013

In order to achieve significant secondary air savings in heavy duty gas turbines, a remarkable item of improvement is the reduction of seal flows for turbine stator-rotor cavities. The optimization of such flows allows to avoid waste of air, obligatory with standard labyrinth seals, to ensure the minimum sealing flow rate in all operating conditions.
Based on the experience gained in the design of sealing system of stator-rotor cavities with standard seals, the project of installation of inter-stage brush-seals was undertaken incorporating such devices into the vane seal rings of 2nd and 3rd turbine stages of a AE94.3A Gas Turbine (GT).
The paper offers a detailed description of the installation project. The following describes in detail the design flow process and the calculation methodologies used, step by step, to define the geometry of brush-seals in order to ensure mechanical integrity and durability, needed in the commercial operation, without thereby affecting the performance.
The first prototype of brush-seal devices has been installed on a AE94.3A4 unit of the Ansaldo fleet. In order to verify the behavior of stator-rotor sealing system, in particular in terms of temperature and pressure variations, vane seal rings have been equipped with special instrumentation. A series of tests to optimize the set points of bleed control valves was carried out.
On the Combined Effect on Operating Range of Adjustable IGVs and Variable Speed in Process Multistage Centrifugal Compressors
Authors: Del Greco Alberto Scotti , Tapinassi Libero 
Published: November 2013

Adjustable inlet guide vanes (IGVs) and variable speed drivers are known as providing process compressors with an effective regulation all throughout the operating envelope of the machine. A large number of works exists in literature reporting the successful control of multistage centrifugal compressors by means of IGVs or speed separately, while a few studies document the combined use of both devices and their effect on compressor performance.
The present paper details the off-design behavior of a multistage centrifugal compressor equipped with both types of control. It is shown that classical IGVs advantage in extending the operating envelope of a fixed speed multistage compressor tends to reduce when speed regulation is active too. In this sense, the average level of peripheral Mach numbers inside the compressor may be interpreted as a sort of threshold, since it deeply affects the stage mismatching at off-design conditions.
This consideration is corroborated by a number of applications in a wide range of design peripheral Mach numbers. Based on those cases, the paper reviews the general effectiveness of the combined regulation, thus outlining some general rules of thumb for the choice of the optimal control device for a multistage centrifugal compressor.
Development of a Tool for Temperature Estimation From Microstructural Condition of a NiCoCrAlY+Re Coating Applied on the Surface of Gas Turbine Hot Components
Authors: Costa Alessio , Vacchieri Erica , Barbareschi Emma , Guarnone Paola , Bonadei Alessandra , Calcagno Claudia 
Published: November 2013

The hot gas path components of gas turbines have to withstand to severe conditions in terms of high temperature oxidation, hot corrosion and creep-fatigue phenomena. The evaluation of components residual life is an important matter for gas turbines producers and the estimation of service temperatures is a key tool for this evaluation.
The most diffused methods to estimate service temperatures of gas turbines blades and vanes in Ni based superalloys are related to the microstructural evolution of the dispersed intermetallic phase γ′, Ni3Al. The aim of this work has been the determination of a tool to estimate service temperature on the basis of the microstructural evolutions of a NiCoCrAlY+Re coating. In order to obtain a deep characterisation of the coating after exposure at different durations and temperatures, an extensive experimental test program has been planned.
Samples of Ni based superalloys, covered by the investigated coating, have been aged in chamber furnaces in the temperature range 700°C – 1000°C with durations up to 20000 hours.
The microstructure of this coating is characterised by β phase, NiAl, which is the Al reservoir, embedded in the matrix, that is constituted by γ′ phase at low temperature and by γ phase over 900°C. Moreover, electron back scattered diffraction (EBSD) and X-ray diffraction (XRD) measurements on samples have revealed three classes of secondary phases: the first one has been identified as σ-Cr2Re3, the second one as Cr carbide-Cr23C6 and the third one as α-Cr. σ phase is very abundant at the lower temperatures while it disappears after long exposures at temperatures higher than 900°C. The σ phase composition is different at different temperatures and the Re content in particular increases with the temperature.
Starting from the σ phase composition determined at different temperatures, a tool has been constructed that relates the service temperature to the Re content in the same phase. The new tool has been applied to the analyses of different components.
The results of the new method have been compared to those ones obtained with the method based on γ′ features, developed in the past through huge experimental campaigns. The agreement between the two methods is generally good, they can be used in a complementary way due to the fact that the γ′ one seems to be more suitable for high temperature ranges (T>900°C) where it gives a reliable estimation, while the sigma method is more suitable in the temperature range 700°C – 900°C.
Identifying Key Technology Areas to Fundamentally Reduce Risk in Engine Performance and Noise for Future Commercial Applications
Authors: Kestner Brian K. , Jimenez Hernando , Perullo Christopher A. , Schutte Jeff S. , Mavris Dimitri N. 
Published: November 2013

There have been many studies in the past which have evaluated the potential fuel savings benefits of various engine technologies applied simultaneously to a gas turbine engine. Coupled with the inclusion of new engine technology is almost always a change to the engine cycle design in order to maximize the full benefits of the technology. Current research focuses on the trends in benefits due to potential technologies and cycle design changes and identifies which specific technology areas can be targeted to reduce risk relative to meeting performance goals. The results are used to identify high priority technologies that increase the chances of meeting performance metrics. Such investigations can add value to government and industry entities that are engaging in aviation technology development programs attempting to simultaneously meet reduction goals for noise and fuel burn.
Jet and fan noise are primary sources of noise on current engine architectures. Noise suppression technologies can be applied to current engine designs to suppress sources of noise thereby reducing the noise impact of the engine. Similarly, the engine cycle can be changed to reduce noise and fuel burn. The critical link is that feasible engine cycles are tightly coupled to the subsystem technologies applied to various engine components. This leads to two critical questions. First, what part of the engine cycle is key to simultaneously meeting noise and fuel burn goals? This inevitably leads to one of three areas, the propulsor (BPR), the core (OPR), or the transmission mechanism between the core and propulsor. The other question is: which subsystem technologies are crucial to achieve the necessary core, propulsor, or power transmission improvements?
To answer these questions, this study examines and quantifies the potential benefits in technologies developed for both noise source reduction and thermal / propulsive efficiency increases. Trade studies on the potential impacts of each of the technologies are performed to capture the sensitivity on fuel burn and noise from changes to assumed benefits of the engine cycle and applied subsystem technologies. It will be demonstrated that a geared transmission is the primary enabler to simultaneously meeting performance goals. Should the geared transmission fall short, other areas of improvement simply cannot overcome the shortfall in fuel burn and noise.
Development and Validation of a Methodology for Stationary Gas Turbine Performance Prognostic
Authors: Alkmin Freire Ronaldo Lucas , Barbosa João Roberto 
Published: November 2013

The gas turbines have been under intense technological development during the past decades. Among the factors that motivate manufacturers to develop differentiated products, it can be cited the rising fossil fuels prices, environmental legislation and increasingly restrictive competition with other alternatives to generate power. Even in the current scenario of global economic crisis, manufacturers and users expect an increase in the number of gas turbines in operation.
In offshore oil & gas exploration, the thermal efficiency of gas turbines has been traditionally at the background compared to the operational continuity. However, nowadays many operators are investing in subsea pipelines to export the associated gas produced in the platforms. In this scenario, the gas, which has been traditionally burned at the flare system, now represents a commercial product.
Performance monitoring of gas turbines for diagnostic of failures has been developed by researchers over the last decades. There are several diagnostic methodologies currently available in the open literature; however, the amount of publications demonstrating successful application in real cases is still reduced. Regarding the application of performance monitoring for prognostic of failures, the scenario is even more premature. Despite of that, both diagnostic and prognostic techniques are seen as very promising from the user point-of-view.
This paper proposes a methodology for performance prognostic based on parameters effectively measured by typical instruments of commercial units. The method makes use of the performance modeling easily found in the literature. The performance parameters measured and also calculated are then corrected to a reference condition in order to eliminate the effects of the variable ambient condition. Future performance parameters are then extrapolated. The methodology was validated through real data of a gas turbine operating in an oil platform. The results showed that the method produces useful information to support the operation and maintenance teams.
Effect of Water Temperature on the Performance of Gas Turbine Inlet Air-Fogging Systems
Authors: Chaker Mustapha A. , Meher-Homji Cyrus B. 
Published: November 2013

With more than 1000 fogging systems installed worldwide on a wide range of gas turbines of different types, gas turbine inlet air fogging systems have become a well-established technology used to increase gas turbines power output.
The major benefit of spraying fog droplets in the inlet airflow of the gas turbines is to increase the density of the air entering the gas turbine by evaporative cooling in the inlet air stream. Significant amount of research has been carried out to improve the efficiency of fogging systems. However, the effect of water temperature on the overall efficiency of a fogging system has yet to be addressed. In this paper, a detailed analysis of this effect will be presented, both from an experimental and a theoretical view point.
Due to the small size of the droplets used in this application, the temperature of the droplet converges quickly to the wet bulb temperature, regardless of the initial water temperature. The rapidity at which this convergence occurs depends on the initial droplet size, the water temperature, the air mass flow to mass of injected water ratio, and the ambient psychrometric conditions of the surrounding air.
The present study was carried out using water temperatures between 1 °C and 60 °C. Results showed that the water temperature has no significant effect on the droplet size. However, within the range of droplet sizes atomized from nozzles installed in the fogging system, using cold water provides a marginal benefit on the cooling efficiency; using hot water, on the other hand, slightly increases the evaporation efficiency.
Flame and Flow Topologies in an Annular Swirling Flow
Authors: Chterev I. , Foley C. W. , Kostka S. , Caswell A. W. , Jiang N. , Seitzman J. M. , Lieuwen T. C. 
Published: November 2013

A variety of different flame configurations and heat release distributions, with their associated flow fields, can exist in high swirl, annular flows. Each of these different configurations, in turn, has different thermoacoustic sensitivities and influences on combustor emissions, nozzle life, and liner heating. These different configurations arise because at least three flame stabilization locations are present, associated with the inner and outer shear layers of the annulus, and the stagnation point of the vortex breakdown region.
This paper discusses the flame and flow topologies that exist in these flows. These results illustrate the importance of the sensitivity of flame configurations to geometric (such as centerbody size and shape, combustor diameter, exhaust contraction) and operational (e.g., bulkhead temperature, preheat temperature, fuel air ratio) parameters. We particularly emphasize the centerbody shape as differentiating between two different families of flame shapes. Results are shown illustrating the time averaged and instantaneous flame shape and flow fields, using high speed PIV, OH-PLIF, and luminosity imaging.
Draft Genome Sequence of Lactobacillus fermentum Lf1, an Indian Isolate of Human Gut Origin
Authors: Grover Sunita , Sharma Vineet K. , Mallapa Rashmi H. , Batish Virender K. 
Published: November 2013

ABSTRACT

Lactobacillus fermentum
is a normal inhabitant of the human gastrointestinal tract. Here, we report the draft genome sequence of an Indian isolate of the probiotic strain
L. fermentum
Lf1, isolated from the human gut.
Metagenome Sequencing of Prokaryotic Microbiota from Two Hypersaline Ponds of a Marine Saltern in Santa Pola, Spain
Authors: Fernandez Ana B. , Ghai Rohit , Martin-Cuadrado Ana Belen , Sanchez-Porro Cristina , Rodriguez-Valera Francisco , Ventosa Antonio 
Published: November 2013

ABSTRACT
Marine salterns are composed of several shallow ponds with a salinity gradient, from seawater to salt saturation, with gradually changing microbial populations. Here, we report the metagenome sequencing of the prokaryotic microbiota of two ponds with 13% and 33% salinity from a saltern in Santa Pola, Spain.
Nosocomial Outbreak of Salmonella enterica Serovar Typhimurium Primarily Affecting a Pediatric Ward in South Africa in 2012
Authors: Smith Anthony M. , Mthanti Mnikelwa A. , Haumann Carel , Tyalisi Nomalungisa , Boon Gerald P. G. , Sooka Arvinda , Keddy Karen H. 
Published: November 2013

ABSTRACT

We describe a nosocomial outbreak of diarrheal disease caused by extended-spectrum β-lactamase-producing multidrug-resistant
Salmonella enterica
serovar Typhimurium, focused on a pediatric ward in South Africa. The outbreak peaked between May 2012 and July 2012. Person-to-person transmission was the most likely mechanism of spread of the infection, expedited due to a breakdown in hand-washing and hygiene, suboptimal infection control practices, overcrowding of hospital wards, and an undesirable nurse-to-patient ratio.