Challenges of detecting and monitoring flames in hydrogen-burning gas turbines
This is an excerpt from 'Hydrogen combustion in turbines: the role of flame sensors in fueling the future'
Hydrogen combustion challenges
Detecting and monitoring hydrogen flames in combustors presents several technical challenges, due to the unique properties of hydrogen and the characteristics of hydrogen combustion. These challenges stem from factors such as the visibility of the flame, the spectral characteristics of hydrogen combustion, and the potential for combustion instabilities.
The high reactivity of hydrogen can increase the risk of auto-ignition in the premixing section of combustion systems, particularly in systems with very high air inlet temperatures.
Hydrogen flames also exhibit different thermoacoustic behavior than natural gas flames due to their higher flame speed, shorter ignition delay time, and distinct flame stabilization mechanisms. This results in different flame shapes, positions, and reactivity. The high flame speed of hydrogen can result in rapid heat release rates and increased turbulent flow within the combustion chamber.
When burning 100% hydrogen or hydrogen/natural gas mixtures in a gas turbine, these combustion phenomena require many physical design changes.
Component design for hydrogen applications
Advanced combustion control strategies and design modifications are generally required to manage the dynamic behavior of hydrogen combustion and ensure the stable and efficient operation of gas turbines.
When hydrogen is burned instead of natural gas, the exhaust becomes more humid. Moisture in the combustion gases leads to increased heat transfer to the hot gas path components.
Incorporating redundancy and fault-tolerant design features in flame sensor systems enhances reliability and safety in hydrogen-rich combustion environments. Installing multiple sensors at different locations on the gas turbine provides backup functionality and ensures continuous flame monitoring, even in the event of sensor failures.
