The 60Hz, 165MW gas turbine GT24 and the 50Hz, 240MW gas turbine GT26 are the first two members of ABB’s Sequential Combustion System gas turbine family. These turbines are designed to offer increased output at up to 4% efficiency advantage over today’s engines. Whereas the first combustor is based on the proven EV-combustor technology, an extensive research and development program has been carried out in developing the lean premixed, self-igniting second combustor. This paper reports the basic research work concerning the lean premixing burners with self-ignition. The development of the burner and the combustor was based on wind tunnel and water channel experiments, CFD-calculations and combustion tests at atmospheric and high pressure. Moreover an innovative cooling technology was developed to fullfill all conditions of the self-igniting premix combustor requiring minimal cooling air consumption. Special attention was paid both to a low sensitivity of the cooling effectiveness to variations of the imposed boundary conditions and to a robust hardware construction. Tests of real engine parts at real engine conditions will be demonstrated in detail. Finally the paper demonstrates the potential of the sequential combustion system to reach single digit NOx levels by unveiling the results of the extensive testing program.
Effects of exponential acceleration on penetration and mixing characteristics of a jet in cross ow have been investigated experimentally in a water model. To impose an exponential acceleration on the ow, both the injection speed and the nozzle width of the jet increased exponentially in the downstream direction of the cross ow. An acceleration parameter ® is de ned as the ratio of the revolution time of the longitudinal vortex pair to the e-folding time of the acceleration. Theoretically, a signi cant reduction in turbulent entrainment and mixing of the jet with the cross ow is expected as ® nears unity or as the revolution time of the longitudinal vortex pair in the jet becomes comparable to the characteristic time of acceleration. It was found that the diameter of each vortex in the near-eld jet cross section is reduced more than a factor of three as ® is increased from 0 to 2.5. In the same ® range, the jet ame or reaction length increased up to 50%, revealing a strong effect of the near-eld forcing on the far-eld molecular scale mixing. Furthermore, the experiments have shown up to a 50% increase in the penetration of the jet into the cross ow as a result of the acceleration , when compared with a conventional transverse jet. These results demonstrate clearly that, in a free-shear ow, imposing a new timescale by means of an external acceleration in uences the entrainment and mixing characteristics dramatically, thus providing a new possibility of controlling the ow characteristics.
Advanced combustor design for gas turbines in power generation is driven by reliability, lifetime and emission requirements, by needs for fuel flexible operation, and minimization of cost of electricity. The present paper explains in detail the basic design principles of the annular combustors, as implemented in the most recent upgrades of the GT13E2 and GT24/GT26 engine families. One fundamental principle is the choice of a premix burner system with low pressure drop, allowing serial combination of a convective cooling scheme by fuel-air premixing with almost all available air. This allows operating at the lowest possible flame temperature, for a given hot gas temperature, thus assuring the minimum NOx emissions. Introduction of advanced seals reduce the leakage of air, helping further to reduce the flame temperature and improve burnout and stability. A second distinct feature of annular combustors is the possibility of single- and multiple-row burner arrangements for optimized operational flexibility. Burner arrangements are further optimized to yield the best stability with low heat loads to combustor walls and more uniform exit temperature distribution over the entire engine load range. Another feature of the modular combustion chambers is the separation of cold load-carrying structures and hot heat-shielding elements, which allows for easy maintenance and minimization of air leakages. Examples for the most recent component upgrades will be given in the full paper, with a focus on the reheat (SEV) combustor improvements for increased robustness and life-time, whilst maintaining combustion performance and minimizing cost. Field-feedback has proven to be an important element to understand and exploit the full lifetime potential of this design concept. A comprehensive account of field data from both EV and SEV combustors are presented, accounting more than one and a half decade long operation experience with annular combustors.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.