Session: 04-28 Emissions Hydrogen/Ammonia I

Paper Number: 153886

Mixing Performance of Adjustable High Flame Speed Injector Configurations and NOx Emissions From a Recuperated Gas Turbine Operated on 100% Hydrogen 

Multiple configurations of a set of high flame speed (HFS) injectors with an adjustable fuel distributor for a commercial natural gas 65 kW microturbine generator (MTG) are investigated in this work. The adjustable HFS injectors are derivatives of a baseline design that allowed successful operation of a Capstone 65 kW MTG on 100% hydrogen without flashback from cold start to full power to shut down. The adjustability of the fuel distributor provides control of where inside the injector the fuel and air begin to mix and also facilitated different amounts of air introduced to mix with the hydrogen. This provides adjustment of mixing time and fuel/air ratio within the injector which, in principle, can reduce NOx emissions by reducing fuel rich areas at the injector outlet. In addition to investigating the effect of adjusting the fuel distributor, the mixing performance of an injector variant with more open area for airflow is examined. Fuel concentration gradients from 3 different injector configurations, i.e. fuel distributor at different points and different amounts of open area for air inlet, were measured. Perhaps surprisingly, the injector open area did not dramatically change the velocity of the air at the exit plane.  Further, the configurations studied did not result in significantly improved mixing.  Finally, the measured NOx emissions exhibited an increase compared to the baseline design.  The experimental work is complemented by high fidelity simulations which can be used to elucidate additional details about the inject flow field and dynamic mixing behavior.  The results show that despite adjusting the mixing strategy within the injector, changes in air momentum associated with the increase in open area actually degrades the fuel/air mixing.  Thus, while further demonstration of successful operation of a premixed approach on 100% hydrogen, further effort is required to attain the desired low NOx emission levels.

Presenting Author: Vincent Mc Donell UCI

Presenting Author Biography: prof

Authors:

Walther Villatoro UCI Combustion Laboratory
Vincent Mc Donell UCI
Debolina Dasgupta Argonne National Laboratory
Ray Hu Capstone Green Energy
Robert Steele EPRI