Exergy-based performance analysis of the heavy-duty gas turbine in part-load operating conditions

2002 ◽  
Vol 2 (2) ◽  
pp. 105-112 ◽  
Author(s):  
T.W. Song ◽  
J.L. Sohn ◽  
J.H. Kim ◽  
T.S. Kim ◽  
S.T. Ro
Keyword(s):  
Performance Analysis ◽  
Gas Turbine ◽  
Operating Conditions ◽  
Heavy Duty ◽  
Part Load ◽  
Heavy Duty Gas Turbine

Experience With Large Heavy-Duty Gas Turbine Rotors

1981 ◽  
Author(s):  
O. R. Schmoch ◽  
B. Deblon
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Turbine Rotor ◽  
Strength Properties ◽  
Operating Conditions ◽  
Material Strength ◽  
Heavy Duty ◽  
Turbine Rotors ◽  
Heavy Duty Gas Turbine ◽  
Response To Temperature

The peripheral speeds of the rotors of large heavy-duty gas turbines have reached levels which place extremely high demands on material strength properties. The particular requirements of gas turbine rotors, as a result of the cycle, operating conditions and the ensuing overall concepts, have led different gas turbine manufacturers to produce special structural designs to resolve these problems. In this connection, a report is given here on a gas turbine rotor consisting of separate discs which are held together by a center bolt and mutually centered by radial serrations in a manner permitting expansion and contraction in response to temperature changges. In particular, the experience gained in the manufacture, operation and servicing are discussed.

scholarly journals Gas turbine efficiency and ramp rate improvement through compressed air injection

2020 ◽  
pp. 095765092093208 ◽  
Author(s):  
Kamal Abudu ◽  
Uyioghosa Igie ◽  
Orlando Minervino ◽  
Richard Hamilton
Keyword(s):  
Gas Turbine ◽  
Guide Vane ◽  
Injection Rate ◽  
Inlet Guide Vane ◽  
Heavy Duty ◽  
Part Load ◽  
Surge Margin ◽  
Rate Improvement ◽  
Heavy Duty Gas Turbine ◽  
Variable Inlet Guide Vane

With the transition to more use of renewable forms of energy in Europe, grid instability that is linked to the intermittency in power generation is a concern, and thus, the fast response of on-demand power systems like gas turbines has become more important. This study focuses on the injection of compressed air to facilitate the improvement in the ramp-up rate of a heavy-duty gas turbine. The steady-state analysis of compressed airflow injection at part-load and full load indicates power augmentation of up to 25%, without infringing on the surge margin. The surge margin is also seen to be more limiting at part-load with maximum closing of the variable inlet guide vane than at high load with a maximum opening. Nevertheless, the percentage increase in the thermal efficiency of the former is slightly greater for the same amount of airflow injection. Part-load operations above 75% of power show higher thermal efficiencies with airflow injection when compared with other load variation approaches. The quasi-dynamic simulations performed using constant mass flow method show that the heavy-duty gas turbine ramp-up rate can be improved by 10% on average, for every 2% of compressor outlet airflow injected during ramp-up irrespective of the starting load. It also shows that the limitation of the ramp-up rate improvement is dominated by the rear stages and at lower variable inlet guide vane openings. The turbine entry temperature is found to be another restrictive factor at a high injection rate of up to 10%. However, the 2% injection rate is shown to be the safest, also offering considerable performance enhancements. It was also found that the ramp-up rate with air injection from the minimum environmental load to full load amounted to lower total fuel consumption than the design case.

Design Improvement Survey for NOx Emissions Reduction of a Heavy-Duty Gas Turbine Partially Premixed Fuel Nozzle Operating With Natural Gas: Numerical Assessment

2015 ◽  
Vol 138 (1) ◽  
Author(s):  
Alessandro Innocenti ◽  
Antonio Andreini ◽  
Bruno Facchini ◽  
Matteo Cerutti ◽  
Gianni Ceccherini ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Turbulent Combustion ◽  
Operating Conditions ◽  
Combustion Model ◽  
Formation Mechanisms ◽  
Heavy Duty ◽  
Flamelet Generated Manifold ◽  
Fuel Nozzle ◽  
Partially Premixed ◽  
Heavy Duty Gas Turbine

A numerical investigation of a low NOx partially premixed fuel nozzle for heavy-duty gas turbine applications is presented in this paper. Availability of results from a recent test campaign on the same fuel nozzle architecture allowed the exhaustive comparison study presented in this work. At first, an assessment of the turbulent combustion model was carried out, with a critical investigation of the expected turbulent combustion regimes in the system and taking into account the partially premixed nature of the flame due to the presence of diffusion type pilot flames. In particular, the fluent partially premixed combustion model and a flamelet approach are used to simulate the flame. The laminar flamelet database is generated using the flamelet generated manifold (FGM) chemistry reduction technique. Species and temperature are parameterized by mixture fraction and progress variable. Comparisons with calculations with partially premixed model and the steady diffusion flamelet (SDF) database are made for the baseline configuration in order to discuss possible gains associated with the introduced dimension in the FGM database (reaction progress), which makes it possible to account for nonequilibrium effects. Numerical characterization of the baseline nozzle has been carried out in terms of NOx. Computed values for both the baseline and some alternative premixer designs have been then compared with experimental measurements on the reactive test rig at different operating conditions and different split ratios between main and pilot fuel. Numerical results allowed pointing out the fundamental NOx formation processes, both in terms of spatial distribution within the flame and in terms of different formation mechanisms. The obtained knowledge would allow further improvement of fuel nozzle design.

Numerical Analysis of the Dynamic Flame Response and Thermo-Acoustic Stability of a Full-Annular Lean Partially-Premixed Combustor

2016 ◽  
Author(s):  
Alessandro Innocenti ◽  
Antonio Andreini ◽  
Bruno Facchini ◽  
Matteo Cerutti
Keyword(s):  
Dynamic Response ◽  
Gas Turbine ◽  
Operating Conditions ◽  
System Stability ◽  
Driving Mechanism ◽  
Heavy Duty ◽  
Flame Response ◽  
Partially Premixed ◽  
Heavy Duty Gas Turbine ◽  
Acoustic Stability

A thermo-acoustic stability of a full-annular lean partially-premixed heavy-duty gas turbine combustor is carried out in the present paper. A sensitivity analysis is performed, varying the flame temperature for two operating conditions. The complex interaction between the system acoustics and the turbulent flame is studied in Ansys Fluent, using Unsteady-RANS simulations with Flamelet-Generated Manifolds combustion model. Perturbations are introduced in the system imposing a broadband excitation as inlet boundary condition. The flame response is then computed exploiting system identification techniques. The identified flame transfer functions are compared each other and the results analysed in order to give more physical insight on the coupling mechanisms responsible for the flame dynamic response. The effect of fuel mass flow fluctuations is then introduced as further driving input, describing the flame as a Multi-Input Single-Output system. Further in-depth studies are carried out on pilot flames aiming at replicating the dynamic response of the real flame and understanding the driving mechanism of thermo-acoustic instability onset as well. The obtained results are implemented into a finite element model of the combustor, realized in COMSOL Multiphysics, to analyse the system stability. Numerical model affordability has been assessed through comparisons with results from full-annular combustor experimental campaign carried out by GE Oil & Gas since the early phases of the design and development of a heavy-duty gas turbine. This allowed the discussion of the model ability to describe the stability properties of the combustor and to catch the instabilities onset as detected experimentally. Valuable indications for future design optimization were also identified thanks to the obtained results.

Performance and Numerical Flow Investigations of an Industrial Gas Turbine Intake System Under Different Operating Conditions

2006 ◽  
Author(s):  
Friederike C. Mund ◽  
Pericles Pilidis
Keyword(s):  
Gas Turbine ◽  
Operating Conditions ◽  
Relative Reduction ◽  
Maximum Deviation ◽  
Heavy Duty ◽  
Flow Distortion ◽  
Local Flow ◽  
Intake System ◽  
Heavy Duty Gas Turbine ◽  
Industrial Gas Turbine

An important loss in an industrial gas turbine is caused by the intake system. Even though these losses have a direct effect on the performance of the engine, the design of the intake system is dominated by local space restriction. Consequently, intake losses are site specific parameters. They correlate with the airflow velocity and therefore operating conditions of the engine affect the intake performance. But due to the high experimental effort necessary to investigate intake losses, only sparse information about this effect is available. For the present study a typical vertical industrial intake duct was investigated numerically for different operating scenarios. The performance simulation of a single shaft heavy duty gas turbine provided boundary conditions for the CFD (Computational Fluid Dynamics) study of the intake duct. For all operating conditions a large scale vortex developed in the intake plenum and entered the compressor. Bearing support struts caused local flow distortion at the compressor inlet. Even for extreme operating scenarios the relative changes of pressure recovery compared to the design point value were small (0.1%). However, the resulting power change was generally in excess of the intake loss deviation. Applied to a heavy duty gas turbine, the maximum deviation of 0.2% of power was equivalent to about 0.4 MW. In most cases lower pressure losses were predicted which benefited the overall engine performance. For the cold scenario the intake performance deteriorated and resulted in a relative reduction of power of nearly 0.5 MW.

Design of a Non-Reactive Warm Rig With Real Lean-Premix Combustor Swirlers and Film-Cooled First Stage Nozzles

2020 ◽  
Author(s):  
Simone Cubeda ◽  
Tommaso Bacci ◽  
Lorenzo Mazzei ◽  
Simone Salvadori ◽  
Bruno Facchini ◽  
...  
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Operating Conditions ◽  
Pollutant Emissions ◽  
Heavy Duty ◽  
Design Practices ◽  
Standard Design ◽  
Real Hardware ◽  
Heavy Duty Gas Turbine

Abstract Modern industrial gas turbines typically employ lean-premix combustors, which can limit pollutant emissions thanks to premixed flames, while sustaining high turbine inlet temperatures that increase the single-cycle thermal efficiency. As such, gas-turbine first stage nozzles can be characterized by a highly-swirled and temperature-distorted inlet flow field. However, due to several sources of uncertainty during the design phase, wide safety margins are commonly adopted, having a direct impact on engine performance and efficiency. Therefore, aiming at increasing the knowledge on combustor-turbine interaction and improving standard design practices, a non-reactive test rig composed of real hardware was assembled at the University of Florence, Italy. The rig, accommodating three lean-premix swirlers within a combustion chamber and two first stage film-cooled nozzles of a Baker Hughes heavy-duty gas turbine, is operated in similitude conditions. The rig has been designed to reproduce the real engine periodic flow field on the central vane channel, also allowing for measurements far enough from the lateral walls. The periodicity condition on the central sector was achieved by the proper design of both the angular profile and pitch value of the tailboards with respect to the vanes, which was carried out in a preliminary phase via a Design of Experiments procedure. In addition, circular ducts needed to be installed at the injectors outlet section to preserve the non-reactive swirling flow down to the nozzles’ inlet plane. The combustor-turbine interface section has been experimentally characterized in nominal operating conditions as per the temperature, velocity and pressure fields by means of a five-hole pressure probe provided with a thermocouple, installed on an automatic traverse system. To study the evolution of the combustor outlet flow through the vanes and its interaction with the film-cooling flow, such measurements have been replicated also downstream of the vanes’ trailing edge. This work allowed for designing and providing preliminary data on a combustor simulator capable of equipping and testing real hardware film-cooled nozzles of a heavy-duty gas turbine. Ultimately, the activity sets the basis for an extensive test campaign aimed at characterizing the metal temperature, film effectiveness and heat transfer coefficient at realistic aerothermal conditions. In addition, and by leveraging experimental data, this activity paves the way for a detailed validation of current design practices as well as more advanced numerical methodologies such as Scale-Adaptive Simulations of the integrated combustor-turbine domain.

Investigation of the Flow Field and the Pressure Recovery in a Gas Turbine Exhaust Diffuser at Design, Part-Load and Over-Load Condition

2020 ◽  
Author(s):  
Maximilian Bauer ◽  
Simon Hummel ◽  
Markus Schatz ◽  
Martin Kegalj ◽  
Damian M. Vogt
Keyword(s):  
Mach Number ◽  
Flow Field ◽  
Pressure Distribution ◽  
Gas Turbine ◽  
Total Pressure ◽  
Operating Conditions ◽  
Pressure Recovery ◽  
Heavy Duty ◽  
Part Load ◽  
Design Load

Abstract The performance of axial diffusers installed downstream of heavy duty gas turbines is mainly affected by the turbine load. Thereby the outflow varies in Mach number, total pressure distribution, swirl and its tip leakage flow in particular. To investigate the performance of a diffuser at different load conditions, a generic diffuser geometry has been designed at ITSM which is representative for current heavy duty gas turbine diffusers. Results are presented for three different operating conditions, each with and without tip flow respectively. Part-load, design-load and over-load operating conditions are defined and varied at the diffuser inlet in terms of Mach number, total pressure distribution and swirl. Each operating point is investigated experimentally and numerically and assessed based on its flow field as well as the pressure recovery. The diffuser performance shows a strong dependency on the inlet swirl and total pressure profile. A superimposed tip flow only influences the flow field significantly when the casing flow is weakened due to casing separation. In those cases pressure recovery increases with additional tip flow. There is a reliable prediction of the CFD simulations at design-load. At part-load, CFD overpredicts the strut separation, resulting in an underpredicted overall pressure recovery. At over-load, CFD underpredicts the separation extension in the annular diffuser but overpredicts the hub wake. This leads to a better flow control in CFD with the result of an overpredicted overall pressure recovery.

Effect of Natural Gas Composition on Low NOx Burners Operation in Heavy Duty Gas Turbine

2019 ◽  
Author(s):  
Serena Romano ◽  
Matteo Cerutti ◽  
Giovanni Riccio ◽  
Antonio Andreini ◽  
Christian Romano
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Operating Conditions ◽  
Fuel Composition ◽  
Gas Composition ◽  
Heavy Duty ◽  
Wide Range ◽  
Annular Combustor ◽  
Heavy Duty Gas Turbine ◽  
The Impact

Abstract Development of lean-premixed combustion technology with low emissions and stable operation in an increasingly wide range of operating conditions requires a deep understanding of the mechanisms that affect the combustion performance or even the operability of the entire gas turbine. Due to the relative wide range of natural gas composition supplies and the increased demand from Oil&Gas customers to burn unprocessed gas as well as LNG with notable higher hydrocarbons (C2+) content; the impact on gas turbine operability and combustion related aspects has been matter of several studies. In this paper, results of experimental test campaign of an annular combustor for heavy-duty gas turbine are presented with focus on the effect of fuel composition on both emissions and flame stability. Test campaign involved two different facilities, a full annular combustor rig and a full-scale prototype engine fed with different fuel mixtures of natural gas with small to moderate C2H6 content. Emissions trends and blowout for several operating conditions and burner configurations have been analyzed. Modifications to the burner geometry and fuel injection optimization have shown to be able to reach a good trade-off while keeping low NOx emissions in stable operating conditions for varying fuel composition.

Dry Low NOx Emissions Operability Enhancement of a Heavy-Duty Gas Turbine by Means of Fuel Burner Design Development and Testing

2018 ◽  
Author(s):  
Matteo Cerutti ◽  
Nicola Giannini ◽  
Gianni Ceccherini ◽  
Roberto Meloni ◽  
Emanuele Matoni ◽  
...  
Keyword(s):  
Gas Turbine ◽  
Operating Conditions ◽  
Design Development ◽  
Heavy Duty ◽  
Design Changes ◽  
Wide Range ◽  
Development Phases ◽  
Burner Design ◽  
Heavy Duty Gas Turbine ◽  
Fuel Burner

This paper describes the development phases of an annular type combustor for heavy-duty gas turbine applications. High cycle efficiency and low emissions are required over a wide range of load conditions, with the consequence of reducing margin to thermo-acoustic instability onset and lean blow-out. In addition, in lean premixed combustors, the increased fuel air mixing times required to keep emissions low, may lead to undesired ignition or flashback into the fuel burner ducts. All these aspects are matter of this work and focus is on fuel burner design modifications which allowed dry emissions reduction while maintaining a sufficiently wide safe operation window. A synergic effort has been put in place, involving experimental campaigns and CFD simulations, with the purpose of assessing design changes initially and doing screening. In the meanwhile, numerical practices have taken benefits form the experience growth. Results of past work on similar components has been leveraged too. Test campaign involved different scale facilities, from single burner through full annular combustor up to full scale prototype engine. The progressive reduction of viable option for combustor components design changes, due to high impact of such modifications during the gas turbine late development phases, forced designers to concentrate efforts onto fuel burner optimization, looking for efficient ways to implement modifications and assess their effectiveness of combustion system performances. Emissions trends, blow-out and flashback margin for several burner designs are reported. Numerical analysis results are also shown, which revealed to be well aligned with the experimental outcomes, allowing burner optimized solution to be identified. Finally, characterization with respect to fuel gas composition is shown as well as sensitivity to different operating conditions.

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