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.

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.

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

2019 ◽  
Vol 141 (11) ◽  
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 liquified natural gas (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. Emission 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 tradeoff while keeping low NOx emissions in stable operating conditions for varying fuel composition.

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.

Combustion Instabilities Damping System Development for Dry Low NOx Emissions Operability Enhancement of a Heavy-Duty Gas Turbine

2019 ◽  
Author(s):  
Matteo Cerutti ◽  
Nicola Giannini ◽  
Bruno Schuermans ◽  
Riccardo Brenci ◽  
Alessandro Marini ◽  
...  
Keyword(s):  
Growth Rate ◽  
Gas Turbine ◽  
Growth Rates ◽  
Fine Tuning ◽  
Optimized Design ◽  
Nox Emissions ◽  
Preliminary Design ◽  
Heavy Duty ◽  
Wide Range ◽  
Heavy Duty Gas Turbine

Abstract This paper describes the development phases of a damping system for combustion instability reduction in an annular type combustor for heavy-duty gas turbine applications. As reported by the authors in a previous paper, the full scale annular test rig allowed for an extensive characterization of the combustor with realistic acoustic boundaries at engine-relevant conditions. Emissions and operability assessment over a wide range of load conditions was performed, allowing the evaluation of the response of the system near the thermo-acoustic instability onset. The instability is quantified by its acoustic growth rate. This quantity is a crucial input in the design process of dampers. A methodology has been used to extract these growth rates form measured pulsation data. Experimentally determined growth rates have been evaluated for different fuel flow rate split between the main and the pilot injections, providing input to dampers preliminary design. Given current combustor architecture constraints, a first attempt configuration has been proposed and performances evaluated in the full annular rig. Dampers have been equipped with dynamic sensors and thermocouples with the purpose of measuring the growth rate abatement and the consequent NOx emissions reduction. A dedicated numerical toolbox, in-house developed by GE Power, has been used for both dampers preliminary design and growth rate reduction evaluation. Fine tuning of dampers elements as well as design assumptions adjustments required additional experimental evaluations and design iterations. Encouraged by the successful test in the concept phase, an optimized design for engine implementation was defined, that featured a significant increased damper volume, involving combustor parts re-design. The optimized configuration was finally tested in full annular rig and results demonstrated an important enhancement of operability while maintaining NOx emissions below the target levels.

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.

A Comparative Analysis of Single Nozzle and Multiple Nozzles Arrangements for Syngas Combustion in Heavy Duty Gas Turbine

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Shi Liu ◽  
Hong Yin ◽  
Yan Xiong ◽  
Xiaoqing Xiao
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Heavy Duty ◽  
Gas Turbine Combustor ◽  
Integrated Gasification Combined Cycle ◽  
Wide Range ◽  
Heavy Duty Gas Turbine ◽  
Integrated Gasification

Heavy duty gas turbines are the core components in the integrated gasification combined cycle (IGCC) system. Different from the conventional fuel for gas turbine such as natural gas and light diesel, the combustible component acquired from the IGCC system is hydrogen-rich syngas fuel. It is important to modify the original gas turbine combustor or redesign a new combustor for syngas application since the fuel properties are featured with the wide range hydrogen and carbon monoxide mixture. First, one heavy duty gas turbine combustor which adopts natural gas and light diesel was selected as the original type. The redesign work mainly focused on the combustor head and nozzle arrangements. This paper investigated two feasible combustor arrangements for the syngas utilization including single nozzle and multiple nozzles. Numerical simulations are conducted to compare the flow field, temperature field, composition distributions, and overall performance of the two schemes. The obtained results show that the flow structure of the multiple nozzles scheme is better and the temperature distribution inside the combustor is more uniform, and the total pressure recovery is higher than the single nozzle scheme. Through the full scale test rig verification, the combustor redesign with multiple nozzles scheme is acceptable under middle and high pressure combustion test conditions. Besides, the numerical computations generally match with the experimental results.

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.

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