59236 - Development and Atmospheric Testing of a High Hydrogen Flamesheet™ Combustor for the Op16 Gas Turbine 

Hydrogen is a clean and carbon-free fuel and is considered a key element for the energy transition. Renewable power generation by solar and wind is increasing, requiring flexible operation to balance the load on the energy grid with the ability to rapidly adjust the output. Gas turbines with a combustion system for hydrogen operation offers a low carbon solution to support the stability of the energy grid. This provides a solution capturing the needs for energy storage, in the form of hydrogen, and flexible power generation. Fuel flexibility is a key requirement to reduce the operational risks in case hydrogen is not available, whereby hydrogen can be combined with other conventional or alternative fuels. To address this, a project consortium was set-up consisting of equipment manufacturers, academia and end-users.

The major objective is to develop a cost-effective, ultra-low emissions (sub 9ppm NO_x and CO) combustion system for gas turbines in the 1-300 MW output range, including the 1.85 MWe OPRA OP16 gas turbine. A key requirement is fuel flexibility and stable operation from 100% natural gas to 100% hydrogen and any mixture thereof. This is a key challenge as extreme changes in fuel reactivity switching from natural gas to hydrogen can result in dramatic shifting of heat release within the combustor, which can be physically destructive if not well controlled. At the center of this innovative high-technology project is the patented and novel aerodynamic trapped vortex FlameSheet™ combustion technology platform. A key issue to achieve 100% hydrogen combustion with low emissions is to prevent flashback. Burner concepts based on an aerodynamically trapped vortex flame stabilization have a higher resistance towards flame blowout than conventional swirl stabilized burners.

This paper will present the results of the first phase of the project, whereby atmospheric testing of the upgraded FlameSheet™ combustor has been performed operating on natural gas, hydrogen and mixtures thereof. The design of FlameSheet™ combustor has been optimized to allow higher amounts of hydrogen and is scaled for the OP16 gas turbine. A combination of analytical modelling and operational experience of the FlameSheet™ platform has led to a flexible prototype which allows for the exploration of promising design concepts and iterations during this first phase atmospheric test campaign. Combined with 3D printing technology to create complex mixing design features, the efforts have resulted in a realization from the first ideas to a prototype in an accelerated manner.

The combustor has been tested in OPRA’s state-of-the-art atmospheric combustor test rig. The test rig has recently been upgraded to handle the higher amount of hydrogen required for this project. The results presented in this paper focus on the validation of flashback and flame holding resistance, flame stability, operational window, turn down and emissions operating on different mixtures of hydrogen and natural gas. Various design iterations have been tested, thereby optimizing the flashback margin of the designs.

Starting point in the atmospheric test campaign is validation of the performance of the baseline build. This build is fully based on a scaling of the original large-scale design, currently in commercial operation in multiple F-class gas turbines, and is used as a reference for the following optimized builds. The optimized combustor configurations demonstrated a wide load range on 100% hydrogen, and these results will be presented.

The next steps for high pressure testing and engine demonstration for the OP16 and larger frame machines are reviewed in consideration of the results achieved in this first phase.