Study on the operational window of a swirl stabilized syngas burner under atmospheric and high pressure conditions

Providing better fuel flexibility for future gas turbine generations is a challenge as the fuel range is expected to become significantly wider (natural gas, syngas, etc.). The technical problem is to reach a wide operational window, regarding both operational safety and low emissions. In a previous paper an approach to meet these requirements has already been presented. However, in this previous study it was difficult to exactly quantify the improvement in operational safety due to the fact that the flashback phenomena observed were not fully understood. The present continuative paper is focused on a thorough investigation of operational safety also involving the influence of pressure on flashback and the emissions of the proposed burner concept. To gain better insight in the character of the propagation and to visualize the path of the flame during its upstream motion, tests were done on an atmospheric combustion test rig providing almost complete optical access to the mixing section as well as the flame tube. OH* chemiliuminescence, HS-Mie scattering and ionization detectors were applied and undiluted H₂ was used as fuel for the detailed analysis. To elaborate the influence of pressure on the stability behavior additional tests were done on a pressurized test rig using a downscaled burner. OH* chemiluminescence, flashback and lean blow out measurements were conducted in this campaign, using CH₄, CH ₄/H₂ mixtures and pure H₂. The conducted experiments delivered the assets and drawbacks of the fuel injection strategy, where high axial fuel momentum was used to tune the flow field to achieve better flashback resistance.