Experimental and Numerical Study on Optimizing the Dry Low NOx Micromix Hydrogen Combustion Principle for Industrial Gas Turbine Applications

Author(s):  
Harald H. W. Funke ◽  
Jan Keinz ◽  
Karsten Kusterer ◽  
Anis Haj Ayed ◽  
Masahide Kazari ◽  
...  

Combined with the use of renewable energy sources for its production, hydrogen represents a possible alternative gas turbine fuel for future low-emission power generation. Due to the difference in the physical properties of hydrogen compared to other fuels such as natural gas, well-established gas turbine combustion systems cannot be directly applied to dry low NOx (DLN) hydrogen combustion. The DLN micromix combustion of hydrogen has been under development for many years, since it has the promise to significantly reduce NOx emissions. This combustion principle for air-breathing engines is based on crossflow mixing of air and gaseous hydrogen. Air and hydrogen react in multiple miniaturized diffusion-type flames with an inherent safety against flashback and with low NOx emissions due to a very short residence time of the reactants in the flame region. The paper presents an advanced DLN micromix hydrogen application. The experimental and numerical study shows a combustor configuration with a significantly reduced number of enlarged fuel injectors with high-thermal power output at constant energy density. Larger fuel injectors reduce manufacturing costs, are more robust and less sensitive to fuel contamination and blockage in industrial environments. The experimental and numerical results confirm the successful application of high-energy injectors, while the DLN micromix characteristics of the design point, under part-load conditions, and under off-design operation are maintained. Atmospheric test rig data on NOx emissions, optical flame-structure, and combustor material temperatures are compared to numerical simulations and show good agreement. The impact of the applied scaling and design laws on the miniaturized micromix flamelets is particularly investigated numerically for the resulting flow field, the flame-structure, and NOx formation.

Author(s):  
H. H.-W. Funke ◽  
J. Keinz ◽  
K. Kusterer ◽  
A. Haj Ayed ◽  
M. Kazari ◽  
...  

Combined with the use of renewable energy sources for its production, hydrogen represents a possible alternative gas turbine fuel for future low emission power generation. Due to the difference in the physical properties of hydrogen compared to other fuels such as natural gas, well-established gas turbine combustion systems cannot be directly applied to Dry Low NOx (DLN) hydrogen combustion. The DLN Micromix combustion of hydrogen has been under development for many years, since it has the promise to significantly reduce NOx emissions. This combustion principle for air-breathing engines is based on cross-flow mixing of air and gaseous hydrogen. Air and hydrogen react in multiple miniaturized diffusion-type flames with an inherent safety against flash-back and with low NOx-emissions due to a very short residence time of the reactants in the flame region. The paper presents an advanced DLN Micromix hydrogen application. The experimental and numerical study shows a combustor configuration with a significantly reduced number of enlarged fuel injectors with high thermal power output at constant energy density. Larger fuel injectors reduce manufacturing costs, are more robust and less sensitive to fuel contamination and blockage in industrial environments. The experimental and numerical results confirm the successful application of high energy injectors, while the DLN Micromix characteristics of the design point, under part load conditions and under off-design operation are maintained. Atmospheric test rig data on NOx emissions, optical flame structure and combustor material temperatures are compared to numerical simulations and show good agreement. The impact of the applied scaling and design laws on the miniaturized Micromix flamelets is particularly investigated numerically for the resulting flow field, the flame structure and NOx formation.


Author(s):  
A. Haj Ayed ◽  
K. Kusterer ◽  
H. H.-W. Funke ◽  
J. Keinz ◽  
M. Kazari ◽  
...  

Combined with the use of renewable energy sources for its production, hydrogen represents a possible alternative gas turbine fuel within future low emission power generation. Due to the large difference in the physical properties of hydrogen compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for Dry Low NOx (DLN) hydrogen combustion. Thus, the development of DLN hydrogen combustion technologies is an essential and challenging task for the future of hydrogen fuelled gas turbines. The DLN Micromix combustion principle for hydrogen fuel is being developed since years to significantly reduce NOx-emissions. This combustion principle is based on cross-flow mixing of air and gaseous hydrogen which reacts in multiple miniaturized diffusion-type flames. The major advantages of this combustion principle are the inherent safety against flashback and the low NOx-emissions due to a very short residence time of reactants in the flame region of the micro-flames. For the low NOx Micromix hydrogen application the paper presents a numerical study showing the further potential to reduce the number of hydrogen injectors by increasing the hydrogen injector diameter significantly by more than 350% resulting in an enlarged diffusion-type flame size. Experimental data is compared to numerical results for one configuration with increased hydrogen injector size and two different aerodynamic flame stabilization design laws. The applied design law for aerodynamic stabilization of the miniaturized flamelets is scaled according to the hydrogen injector size while maintaining equal thermal energy output and significantly low NOx emissions. Based on this parameter variation study the impact of different geometric parameters on flow field, flame structure and NOx formation is investigated by the numerical study. The numerical results show that the low NOx emission characteristics and the Micromix flame structure are maintained at larger hydrogen injector size and reveal even further potential for energy density increase and a reduction of combustor complexity and production costs.


Author(s):  
Antonio Andreini ◽  
Bruno Facchini ◽  
Luca Mangani ◽  
Antonio Asti ◽  
Gianni Ceccherini ◽  
...  

One of the driving requirements in gas turbine design is emissions reduction. In the mature markets (especially the North America), permits to install new gas turbines are granted provided emissions meet more and more restrictive requirements, in a wide range of ambient temperatures and loads. To meet such requirements, design techniques have to take advantage also of the most recent CFD tools. As a successful example of this, this paper reports the results of a reactive 3D numerical study of a single-can combustor for the GE10 machine, recently updated by GE-Energy. This work aims to evaluate the benefits on the flame shape and on NOx emissions of a new pilot-system located on the upper part of the liner. The former GE10 combustor is equipped with fuel-injecting-holes realizing purely diffusive pilot-flames. To reduce NOx emissions from the current 25 ppmvd@15%O2 to less than 15 ppmvd@15%O2 (in the ambient temperature range from −28.9°C to +37.8°C and in the load range from 50% and 100%), the new version of the combustor is equipped with 4 swirler-burners realizing lean-premixed pilot flames; these flames in turn are stabilized by a minimal amount of lean-diffusive sub-pilot-fuel. The overall goal of this new configuration is the reduction of the fraction of fuel burnt in diffusive flames, lowering peak temperatures and therefore NOx emissions. To analyse the new flame structure and to check the emissions reduction, a reactive RANS study was performed using STAR-CD™ package. A user-defined combustion model was used, while to estimate NOx emissions a specific scheme was also developed. Three different ambient temperatures (ISO, −28.9°C and 37.8°C) were simulated. Results were then compared with experimental measurements (taken both from the engine and from the rig), resulting in reasonable agreement. Finally, an additional simulation with an advanced combustion model, based on the laminar flamelet approach, was performed. The model is based on the G-Equation scheme but was modified to study partially premixed flames. A geometric procedure to solve G-Equation was implemented as add-on in STAR-CD™.


Author(s):  
H. H.-W. Funke ◽  
S. Boerner ◽  
J. Keinz ◽  
K. Kusterer ◽  
A. Haj Ayed ◽  
...  

In the future low pollution power generation can be achieved by application of hydrogen as a possible alternative gas turbine fuel if the hydrogen is produced by renewable energy sources such as wind energy or biomass. The utilization of existing IGCC power plant technology with the combination of low cost coal as a bridge to renewable energy sources such as biomass can support the international effort to reduce the environmental impact of electricity generation. Against this background the dry low NOx Micromix combustion principle for hydrogen is developed for years to significantly reduce NOx emissions. This combustion principle is based on cross-flow mixing of air and gaseous hydrogen and burns in multiple miniaturized diffusion-type flames. The two advantages of this principle are the inherent safety against flash-back and the low NOx concentrations due to a very short residence time of reactants in the flame region of the micro-flames. The paper presents experimental results showing the significant reduction of NOx emissions at high equivalence ratios and at simultaneously increased energy density under preheated atmospheric conditions. Furthermore the paper presents the feasibility of enlarged Micromix hydrogen injectors reducing the number of required injectors of a full-scale Micromix combustion chamber while maintaining the thermal energy output with significantly low NOx formation. The experimental investigations are accompanied by 3D numerical reacting flow simulations based on a simplified hydrogen combustion model. Comparison with experimental results shows good agreement with respect to flame structure, shape and anchoring position. Thus, the experimental and numerical results highlight further potential of the Micromix combustion principle for low NOx combustion of hydrogen in industrial gas turbine applications.


Author(s):  
C. Striegan ◽  
A. Haj Ayed ◽  
K. Kusterer ◽  
H. H.-W. Funke ◽  
S. Loechle ◽  
...  

Hydrogen represents a possible alternative gas turbine fuel for future low emission power generation once it can be combined with the use of renewable energy sources for its production. Due to its different physical properties compared to other fuels such as natural gas, well established gas turbine combustion systems cannot be directly applied for Dry Low NOx (DLN) Hydrogen combustion. This makes the development of new combustion technologies an essential and challenging task for the future of hydrogen fueled gas turbines. The newly developed and successfully tested “DLN Micromix” combustion technology offers great potential to burn hydrogen in gas turbines at very low NOx emissions. The mixing of hydrogen and air is based on the jet in cross-flow (JICF) principle, where the gaseous fuel is injected perpendicular into the crossing air stream. The reaction takes place in multiple miniaturized diffusion flames with an inherent safety against flashback and the potential of low NOx emissions due to a short residence time of the reactants in the flame region. Aiming to further develop an existing burner design in terms of an increased energy density, a redesign is required in order to stabilize the flames at higher mass flows while maintaining low emission levels. For this reason, a systematic numerical analysis using CFD is carried out, to identify the interactions of combustion, radiation and heat conduction in the adjacent burner wall by conjugate heat transfer (CHT) methods. Different combustion models are applied, starting from a hybrid eddy break-up model to more advanced turbulence-chemistry interaction approaches considering detailed chemical mechanisms. Those allow an improved prediction of the different NO-pathways of production and consumption. The results of the simulations are in good agreement with atmospheric test rig data of optical flame structure, measured combustor surface temperatures and NOx emissions. The numerical methods help reducing the effort of manufacturing and testing to few designs for single validation campaigns, in order to confirm the flame stability and NOx emissions in a wider operating condition field. Further on, the more detailed CFD-simulations support the understanding of decisive mechanisms to reduce the numerical work to the most important models for further industrial applications in future.


Author(s):  
H. H.-W. Funke ◽  
S. Boerner ◽  
W. Krebs ◽  
E. Wolf

The use of renewable discontinuous energy sources, such as wind- or solar-energy, raises the question of ensuring the continuous demand for energy. For future energy storage scenarios, hydrogen combustion systems play an important role. This offers new opportunities for alternative combustion processes with regard to efficient, safe and low NOx combustion of hydrogen. In addition hydrogen combustion technology will be in need of gas turbine technology for future IGCC power plant concepts. Against the background of ensuring a secure and low NOx combustion of hydrogen, the micromix burning principle is developed since years and was first investigated for the use in aircraft jet engines to significantly reduce NOx-emissions. This combustion principle is based on cross-flow mixing of air and gaseous hydrogen and burns in multiple miniaturized diffusion type flames. The two advantages of this principle are the inherent safety against flash back and the low NOx-emissions due to a very short residence time of reactants in the flame region of the micro-flames. The paper presents an experimental in depth analysis of the combustion principle with regards to low NOx-emissions for higher energy densities. Therefore several geometric variations were investigated and the burning principle was scaled and tested for higher energy densities up to 15 MW/(m2bar). For the different geometries and energy densities, combustion stability, flame anchoring behavior and associated NOx-emissions are tested under preheated atmospheric conditions. The experimental results show the successful scaling of the micromix principle for high energy densities. The general mapping of the test burners demonstrates a wide operating range. Flow phenomena influencing the flame lifting and flame anchoring position with respect to the resulting NOx-emission are analyzed. The investigations highlight further potential for NOx-reduction in industrial gas turbine applications.


2021 ◽  
Vol 13 (3) ◽  
pp. 1360
Author(s):  
Teodora M. Șoimoșan ◽  
Ligia M. Moga ◽  
Livia Anastasiu ◽  
Daniela L. Manea ◽  
Aurica Căzilă ◽  
...  

Harnessing renewable energy sources (RES) using hybrid systems for buildings is almost a deontological obligation for engineers and researchers in the energy field, and increasing the percentage of renewables within the energy mix represents an important target. In crowded urban areas, on-site energy production and storage from renewables can be a real challenge from a technical point of view. The main objectives of this paper are quantification of the impact of the consumer’s profile on overall energy efficiency for on-site storage and final use of solar thermal energy, as well as developing a multicriteria assessment in order to provide a methodology for selection in prioritizing investments. Buildings with various consumption profiles lead to achieving different values of performance indicators in similar configurations of storage and energy supply. In this regard, an analysis of the consumption profile’s impact on overall energy efficiency, achieved in the case of on-site generation and storage of solar thermal energy, was performed. The obtained results validate the following conclusion: On-site integration of solar systems allowed the consumers to use RES at the desired coverage rates, while restricted by on-site available mounting areas for solar fields and thermal storage, under conditions of high energy efficiencies. In order to segregate the results and support optimal selection, a multicriteria analysis was carried out, having as the main criteria the energy efficiency indicators achieved by hybrid heating systems.


Author(s):  
Nicolas Demougeot ◽  
Jeffrey A. Benoit

The search for power plant sustainability options continues as regulating agencies exert more stringent industrial gas turbine emission requirements on operators. Purchasing power for resale, de-commissioning current capabilities altogether and repowering by replacing or converting existing equipment to comply with emissions standards are economic-driven options contemplated by many mature gas turbine operators. NRG’s Gilbert power plant based in Milford, NJ began commercial operation in 1974 and is fitted with four (4) natural gas fired GE’s 7B gas turbine generators with two each exhausting to HRSG’s feeding one (1) steam turbine generator. The gas turbine units, originally configured with diffusion flame combustion systems with water injection, were each emitting 35 ppm NOx with the New Jersey High Energy Demand Day (HEED) regulatory mandate to reduce NOx emissions to sub 10 ppm by May 1st, 2015. Studies were conducted by the operator to evaluate the economic viability & installation of environmental controls to reduce NOx emissions. It was determined that installation of post-combustion environmental controls at the facility was both cost prohibitive and technically challenging, and would require a fundamental reconfiguration of the facility. Based on this economic analysis, the ultra-low emission combustion system conversion package was selected as the best cost-benefit solution. This technical paper will focus on the ultra low emissions technology and key features employed to achieve these low emissions, a description of the design challenges and solution to those, a summary of the customer considerations in down selecting options and an overview of the conversion scope. Finally, a technical discussion of the low emissions operational flexibility will be provided including performance results of the converted units.


2021 ◽  
Author(s):  
A. Ciani ◽  
L. Tay-Wo-Chong ◽  
A. Amato ◽  
E. Bertolotto ◽  
G. Spataro

Abstract Fuel flexibility in gas turbine development has become increasingly important and modern engines need to cope with a broad variety of fuels. The target to operate power plants with hydrogen-based fuels and low emissions will be of paramount importance in a future focusing on electric power decarbonization. Ansaldo Energia AE94.3A engine acquired broad experience with operation of various natural gas and hydrogen fuel blends, starting in 2006 in the Brindisi (Italy) power plant. Based on the exhaustive experience acquired in the field, this paper describes the latest advancements characterizing the operation of the AE94.3A burner with high pressure combustion tests adding hydrogen blends ranging from 0 to 40% in volume. The interpretation of the test results is supported by reactive and non-reactive simulations describing the effects of varying fuel reactivity on the flame structure as well as the impact of fuel / air momentum flux ratio on the fuel / air interaction and fuel distribution in the combustion chamber. As expected, increasing amounts of hydrogen in the fuel are also associated with higher amounts of NOx production, however this effect could be countered by optimization of the fuel staging strategy, based on the mentioned CFD considerations and feedback from high pressure tests.


2019 ◽  
Vol 1 (1) ◽  
pp. 412-418
Author(s):  
Aleksandra Wrzalik ◽  
Matevž Obrecht

AbstractIn recent years heating in Poland has been transformed as a result of the priorities of the country's energy policy implemented within the European Union. The increase in energy security, the development of renewable energy sources and the fulfilment of legal and environmental requirements are very important. Exploitation of district heating systems should ensure reliable and safe heat supplies for industrial and municipal customers with high energy efficiency and reduction of environmental impact. The article discusses the conditions and directions of centralized heating systems development as well as technical and economic issues, which are important for the security of heat supply. The Author describes selected technological innovations used in the technical infrastructure for heat transfer and modern IT systems which are improving the management of heating systems. The article includes the results of simulation research with use of IT tools showing the impact of selected innovations on the improvement of network operation conditions. Directions of modernization of heating systems in the aspect of increasing energy efficiency and security of heat supply have also been indicted here.


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