BIGH2 Innovation / Phase 2

Pre-combustion CO₂ capture produces hydrogen gas (H2) that can be used to fuel power plants with water vapor as the only major product. The challenge is that hydrogen combustion, as opposed to more conventional natural gas combustion, takes place very quickly after the fuel is mixed with the oxidant (high burning velocities, low ignition time delay) and at very high temperatures (high flame temperature). In turn, this implies the formation of very high emissions of pollutants, e.g. NOx emissions in excess of 600 parts-per-million (ppm). Dilution of hydrogen with large amounts of compressed nitrogen or water vapor can reduce NOx emissions but also has a great energy expense and affects the gas turbine thermal efficiency adversely. There is therefore a need to develop new gas turbine burners that may use hydrogen gas as fuel conserving acceptable NOx emissions while minimizing the reduction in thermal efficiency.

What was the project objective?
The project goal of the BIGH2 Phase II project was the development of a novel burner concept for lean premixed combustion (LPC) operation with hydrogen-rich fuels in stationary gas turbines. The specific focus was on the first (high pressure) combustion stage of Alstom’s GT24/26 gas turbine platform based on the sequential combustion concept. Furthermore, the new burner operating window has to show potential for gas turbine operation at different loads or ambient conditions, and with natural gas as backup fuel.

What has the project done in terms of activities?
Alstom has delivered several burner designs to the project. SINTEF has conducted advanced numerical simulations of the burner designs to identify the fundamental aspects behind the burners’ combustion performance. Alstom and DLR have built and tested models of the designs in state-ofthe-art lab experiments. The experimental results have been used to calibrate SINTEF’s numerical models and to further improve the burner designs. The best burner design candidate has been tested under pressure with hydrogen-rich fuels at full scale with encouraging results.

What has the project achieved?
SINTEF has developed world-class expertise in numerical simulation of lean premixed combustion in geometrically complex gas turbine burners and valuable insights into industrial design and development of advanced gas turbines. DLR has developed novel laser-diagnostics techniques and know-how that enables high-speed (kHz repetition rate) and high-definition measurements at pressurized conditions.
ALSTOM has achieved a good understanding of the investigated burner designs and that has allowed for improvement of the burner design. It was possible to successfully test the selected burner design under pressure at small and full scale conditions to get a good understanding of the burner behavior with hydrogen rich fuels. Furthermore, the promising single burner tests allowed the evaluation of the selected concept in a multi-burner configuration to investigate the burner-to-burner interaction phenomena that can be found in gas turbines. Overall, the selected burner concept showed an improvement in the emissions in comparison to well-established gas turbine burners and, although more testing is needed to fully assess its performance before deployment, including comprehensive load range variations and thermo-acoustic stability assessments, the present effort has greatly increased the maturity of this low-NOx combustion system for hydrogen-rich fuels.

Future project phases?
The project partners are in the process of defining the technical content and looking for funding of a Phase III of BIGH2 that will focus on the 2nd combustion stage of the GT24/26 gas turbine platform.

Publications:

Gounder, J. D., et al. “Phase resolved analysis of flame structure in lean premixed swirl flames of a fuel staged gas turbine model combustor.” Combustion Science and Technology 186.4-5 (2014): 421-434.