- Andrea Gruber
- Senior Research Scientist
- 905 52 134
- Thermal Energy
- SINTEF Energi AS
Gas turbines (Task 5)
Task 5 aims to enable deployment of carbon storage on the Norwegian continental shelf through O&G rigs, and throughout Europe with gas turbine engines. The overall objective is to assess the stability and operability of gas turbine combustion systems. Ultimately, the task will evaluate their impact on power generation, thermodynamic efficiency and pollutants emissions.
Full-scale CSS can provide the enormous amounts of energy needed by modern industrial societies without CO2 emissions to the atmosphere. But, there are important technical challenges related to power generation. This is what Task 5 Gas Turbines is looking to solve.
We aim to enable deployment on the Norwegian continental shelf through Oli & Gas rigs, and throughout Europe with gas turbine engines. The gas turbines must be operating stably, cleanly and efficiently.
The overall objective of the task is to assess the stability and operability of gas turbine combustion systems, utilizing the wide range of fuels and working fluids required by different CCS schemes. Ultimately, we will evaluate their impact on power generation, thermodynamic efficiency and pollutants emissions.
Our investigation of the technical challenges related to the power generation provides important insight to both Deployment Cases (DC).
Industry partners are/will be involved in the Task. Ansaldo Energia already participate directly to the work on gas turbines for baseload power generation (primarily related to DC2) while General Electric is considering to join NCCS if the scope of Task 5 can be extended to include topics relevant to industrial gas turbines (primarily related to DC1). Statoil has expressed interest in closely following the technical aspects of the work in view of the company's strategic plans for carbon-free, land-based and off-shore power generation.
Combustion of hydrogen (from the pre-combustion capture route) in state-of-the-art gas turbine combustion systems has been the main focus of the research activities in Task 5. Enabling the near-future clean and efficient hydrogen-firing of gas turbines creates the attractive possibility of a very convenient value-chain synergy. This combines and optimizes power generation based on hydrogen feedstocks obtained via natural gas reforming with CCS and via water electrolysis, powered by Renewable Energy Sources (RES) in periods of excess production.
In 2020, through advanced numerical modelling (DNS), we have made considerable progress in our fundamental understanding of the characteristics of hydrogen combustion at “reheat” conditions. The “reheat” combustion scheme is implemented in Ansaldo’s state-of-the-art commercial heavy-duty gas turbines and represents the most promising technology to achieve stable, clean and efficient hydrogen-firing of H-class gas turbines (the largest and most efficient engines). In parallel with the numerical modelling activity, experimental investigations have focused on the effects of increasing hydrogen content in the fuel mixture on the stability of a model, lab-scale combustor. In the framework of the NCCS-sponsored KPN “Reheat2H2”, the necessary preparations and preliminary activities including analytical modelling, numerical simulation tool and lab setup have been completed during 2020. The research work itself is set to start in 2021.
There were two main achievements during 2020:
Firstly, the unsteady spontaneous ignition process that takes place in hydrogen flames at reheat conditions has been fully characterized with the help of DNS calculations. The conditions (reactants’ temperature, pressure and composition) that lead to a self-excited instability of the flame are charted for a range of relevant flame temperatures and pressure levels to derive a simple relation that is able to predict the time scale of the instability.
Secondly, based on experimental measurements, features of flame transfer function (FTF) have been characterized for turbulent, non-swirled, bluff body stabilized “M” flames for different hydrogen and methane blends, including pure hydrogen flames. A developed model separately considers the impulse response of acoustic velocity fluctuations and vortex shedding and is interpreted as a distribution of time lags between velocity fluctuations and the unsteady heat release rate. This novel distributed time lag (DTL) model is shown to capture all the features of the FTFs, as shown in the figure.
These new fundamental insights are key to assessing and improving the robustness of gas turbine combustors operating on increasing fractions of hydrogen in the fuel mixture and will speed up combustor development by OEMs.
Main results 2019
Task 5 research aims to reduce costs related to clean and efficient energy conversion in gas turbines and improve their safety and robustness. In 2019, we made several important steps towards these goals.
In 2019, we have investigated the spontaneous ignition process in hydrogen flames at reheat conditions, with and without inlet forcing utilizing state-of-the-art direct numerical simulations (DNS). Results indicate the occurrence of unsteady ignition and combustion patterns peculiar to hydrogen reheat flames that have not been observed before. Furthermore, results from full-fledged, three-dimensional DNS have provided turbulent flame speed estimates for hydrogen reheat flames (see left figure) spanning a range of turbulence levels and pressure conditions.
Finally, we have performed measurements of hydrogen/methane premixed flames. Flame Transfer Functions (FTFs) extracted from these measurements revealed a characteristic response pattern not observed earlier (see figure below).
All of this fundamental knowledge is key to assess and improve the robustness of gas turbine combustors operating on pure hydrogen as fuel and will speed up combustor development by OEMs.
NCCS-sponsored KPN “Reheat2H2” was awarded in January, contract work is completed in late spring and project kick-off is arranged on October 23rd (in connection with NCCS CD 2019). The research planned in the KPN Reheat2H2 will optimally complement the ongoing activities of Task 5 and allow special focus to the important issue of combustion dynamics (thermo- acoustic instabilities) in hydrogen reheat flames.
• "Strategy" to start & stabilize reheat flame of 100% hydrogen is established.
• Comprehensive validation of skeletal chemical kinetics scheme for H2/CH4 fuels.
• First laboratory experiments on combustion dynamics of H2/CH4 flames.
The research activities started in mid-2017 at SINTEF and focused on two modelling topics:
- High-definition numerical modelling of the reactive flow in Ansaldo's reheat combustion chamber
- Tuning of the chemical kinetics model to efficiently represent combustion at reheat conditions.
The technical work on both topics was planned and performed in close collaboration with Ansaldo's corporate combustor R&D group with frequent mutual visits between Trondheim and Baden (Switzerland) and with the University of California San Diego (developers of the chemical kinetics model).
Results obtained from the Direct Numerical Simulation (DNS) of a scaled, and geometrically simplified, version of the reheat combustor operating on the target hydrogen-air reactive mixture have provided the first detailed quantification of the combustion characteristics (flame propagation vs auto-ignition) in the device.
On the academic side, the work at NTNU has been mainly related to the preparation/commissioning of the experimental rigs and to the selection and set up of the academic positions (Postdoc/PhD).
Among NCCS industrial partners, Statoil is actively following the research with particular interest in the development of hydrogen-fired gas turbines, providing input and feedback.
- Influence of gas expansion on the propagation of a premixed flame in a spatially periodic shear flow. Feng, Ruixue; Gruber, Andrea; Chen, Jacqueline H.; Valiev, Damir M.. Combustion and Flame 2021 ;Volum 227. s. 421-427
- Direct Numerical Simulation of hydrogen combustion at auto-ignitive conditions: Ignition, stability and turbulent reaction-front velocity. Gruber, Andrea; Bothien, Mirko R.; Ciani, Andrea Camperio; Aditya, Konduri; Chen, Jacqueline H.; Williams, Forman Arthur. Combustion and Flame 2021 ;Volum 229. s. 111385
- Scaling and prediction of transfer functions in lean premixed H2/CH4-flames. Æsøy, Eirik; Aguilar, Jose; Wiseman, Samuel; Bothien, Mirko R.; Worth, Nicholas; Dawson, James. Combustion and Flame 2020 ;Volum 215. s. 269-282
- Development and validation study of a 1D analytical model for the response of reheat flames to entropy waves. Gant, Francesco; Gruber, Andrea; Bothien, Mirko R.. Combustion and Flame 2020 ;Volum 222. s. 305-316
Direct numerical simulation of flame stabilization assisted by autoignition in a reheat gas turbine combustor. Aditya, Konduri; Gruber, Andrea; Xu, Chao; Lu, Tianfeng F.; Krisman, Alex; Bothien, Mirko R.; Chen, Jacqueline H.. Proceedings of the Combustion Institute 2019 ;Volum 37.(2) s. 2635-2642
- Direct numerical simulations of premixed and stratified flame propagation in turbulent channel flow - Andrea Gruber, Edward S. Richardson, Konduri Aditya, and Jacqueline H. Chen
- A skeletal mechanism for prediction of ignition delay times and laminar premixed flame velocities of hydrogen-methane mixtures under gas turbine conditions - Yuanjie Jiang, Gonzalo del Alamo, Andrea Gruber, Mirko R. Bothien, Kalyanasundaram Seshadri, Forman A. Williams