Session: 04-53 High Hydrogen IV

Paper Number: 125086

125086 - Development of a Hydrogen Micro Gas Turbine Combustor: NOx Emissions and Secondary Air Injection 

On the way to a carbon-neutral world, the utilization of fossil energy sources must phase out as soon as possible to limit the impact of climate change. This implies the shift from fossil to clean fuels for combustion-driven processes and machines like gas turbines. Next to biofuels, which are limited due to the available amount of biomass, green hydrogen is a promising alternative to substitute natural gas and other fossil fuels. However, the combustion of hydrogen in premixed gas turbine burners is challenging because reactivity, flame temperature, flame speed and gravimetric energy density are much higher compared to natural gas.

In the H2mGT project, funded by the German Federal Ministry of Economic Affairs and Climate Action, a micro gas turbine (mGT) burner with 100% hydrogen firing is developed and validated in the machine. The project is a collaboration between TU Berlin and the manufacturer Euro-K GmbH. The mGT is considered to be the perfect platform for the implementation of hydrogen combustion on the machine level because the thermal power, temperatures and foremost the operating pressure are much closer to laboratory conditions than at large gas turbines. The project consists of three phases: 1. Atmospheric pressure tests with a fused silica combustion chamber; 2. Atmospheric pressure tests with counterflow-cooled steel combustion chamber and secondary air injection; 3. Validation of the burner in the micro gas turbine at elevated pressure levels. This paper will present the results of Phase 2.

The hydrogen burner is based on an earlier swirl-stabilized burner of TU Berlin and was scaled to match the requirements of the mGT with its 130 kW thermal power. The burner design features multiple geometrical parameters to enable the optimization of the flame towards low NOx emissions. Therefore, a variable swirl intensity, additional axial momentum of air in the mixing tube, a movable center-body and different fuel injection locations are implemented in Phase 1. In Phase 2, the usage of a steel flame tube adds a new parameter, namely the design of the hole pattern in the flame tube. The total air mass flow splits into primary and secondary air, of which only the first actually takes place in the combustion process. The secondary air dilutes the exhaust to cool it down to the acceptable turbine inlet temperature of the turbine. The atmospheric tests found a strong influence of the hole pattern and the hole size onto the NO_x emissions. Besides the stable operation of the flame at base load conditions, a start up procedure was tested in the test rig. Therefore, data from a real mGT start up with conventional fuel, was scaled to hydrogen and atmospheric condition. The resulting data points have been successfully tested in continuous runs at several configurations proving the suitability of the machine for engine tests in Phase 3.

Presenting Author: Tom Tanneberger Technische Universitaet Berlin

Presenting Author Biography: Research assistant at the Chair of Fluid Mechanics in Berlin, working mostly on hydrogen combustion for gas turbines. PhD on hydrogen/oxygen combustion in 2020.

Authors:

Tom Tanneberger Technische Universitaet Berlin
Johannes Mundstock Euro-K GmbH
Christoph Rex Euro-K GmbH
Sebastian Rösch Euro-K GmbH
Christian Oliver Paschereit Technische Universitaet Berlin