Distributed Hydrogen Injection and Combustion Technology for Next Generation Pre-Combustion CCS Schemes

Final report about DiHI-Tech project progress and achievements. The DiHI-Tech project aims to develop an innovative gas turbine burner design and fuel injection technology that is optimized to enable environmental-friendly (low NOx), energy- and cost-efficient (diluent-free fuel) premixed combustion of hydrogen for zero-emission power generation systems. This innovative fuel injection technology is based on the idea of substituting traditional nozzles (tiny millimetre-sized holes) for pointwise fuel injection in gas turbine burners with a completely new fuel injection system that is based on an opportunely shaped porous metal structure (micrometer-sized pores). The proposed concept effectively replaces conventional fuel injection nozzles, thereby eliminating the occurrence of concentrated point sources of the highly reactive hydrogen gas and providing instead its injection in a spatially distributed fashion, ultimately resulting in increased stability of the combustion system. Furthermore, earlier research conducted by SINTEF and DLR in the FME BIGCCS has already shown that porous steel also represents an effective acoustic barrier between flame and fuel system, ultimately resulting in a combustion system that is more resilient to thermo-acoustic instabilities. All project objectives are successfully achieved in the project period. 1) The main outcome of the project is the confirmation that the DIHI-Tech concept for spatially distributed hydrogen injection in a model gas turbine combustor does work as expected also at gas turbine conditions, i.e. high pressure (10 atm) and reactants temperature (573 K) that are the operational limits of SINTEF Energy's HIPROX rig (rated at 100 kW of max thermal load). This is a significant achievement at lab scale and enables eventual further studies and demonstrations at higher TRL level and with the eventual inclusion of a gas turbine OEM. The final set of HIPROX experiments were concluded in December 2020 and January 2021 and a draft paper is produced for submission to the ASME TurboEXPO conference 2022 (submission opens in the summer 2021). 2) The work conducted at NTNU, both on the numerical modelling side and on the laboratory experiments side, has achieved the stated objectives of establishing the needed scaling laws for turbulent scalar mixing of light and fastly-diffusing gases (hydrogen or helium) injected into the main cross-flow of air through a porous surface. Three papers are already published in high-impact journals ("Fuel", "Experiments in Fluids" and "Journal of Fluid Mechanics") and a fourth draft is prepared for submission to the Journal of Fluid Mechanics. 3) The work conducted at SINTEF Industry on the testing and characterisation of hydrogen flow through the porous steel material, at the conditions encountered in the combustion system, has represented an optimal and required complement to both the combustion experiments conducted by SINTEF Energy and the scalar mixing experiments conducted by NTNU. A review paper on material science challenges encountered in hydrogen-fired gas turbines is submitted to the high-impact journal "International Materials Reviews" and is presently under review.

DIHI-Tech har bevist at konseptet for distribuert injeksjon av hydrogen gjennom porøs støl virker som forventet også ved tilstand (høye trykk og temperaturer) som karakteriserer brennkammeret til en gassturbin. Virkningen av prosjektets resultater innebærer at gassturbinbrennkammer som er bedre rustet til å handtere hydrogenrike drivstoff, og samtidig sikre stabil drift og lave utslipp, kan nå utvikles.

The increasing relevance of hydrogen-containing fuels in pre-combustion Carbon Capture and Storage (CCS) for power generation and in energy storage schemes means in practice that modern combustion systems must be able to use these new fuels efficiently while still complying with safety and emissions regulations. The DiHI-Tech project will develop an innovative gas turbine burner design and fuel injection technology that is optimized to enable environmental-friendly (low NOx), energy- and cost-efficient (diluent-free) premixed combustion of hydrogen-rich gaseous fuels. This innovative fuel injection technology is based on a spatially distributed injection system in which hydrogen enters the oxidant stream (typically air) through the surface of an aerodynamically-optimised porous structure. The proposed concept therefore replaces conventional fuel injection nozzles and eliminates the occurrence of concentrated point sources of the highly reactive hydrogen gas providing increased flame stability and reduced tendency to thermo-acoustic oscillations by the combustion system. This is a multi-disciplinary research project that builds upon promising preliminary results obtained within the framework of the (now ended) BIGCCS Research Centre and its main goal is to advance the proposed DiHI-Tech concept from the present Technical Readiness Level (TRL) 3 "Proof of Concept" to TRL 5 "Concept Validated in Relevant Environment". The successful achievement of this target will mature the technology and accelerate its industrial deployment that, in turn, will greatly reduce the economic and energetic cost of pre-combustion CCS schemes by eliminating the need for preparation (separation/pressurization) of large quantities of fuel diluents.