To accommodate the customer’s expectations for operational flexibility and low power generation costs, a gas turbine has to be robust, flexible and cost effective. Since its introduction in 1993 and with its more than 7.5 million operating hours and over 54’000 starts, the GT13E2 gas turbine has already demonstrated to be a most flexible and reliable engine. It is being used in connection with many different applications, and meets a very broad range of environment and operation conditions. The GT13E2 upgrade 2012 described in this paper further improves these capabilities. The next generation of GT13E2 combustors is improved for increased lifetime, reduced total life cycle cost and implementation of a low emission dual fuel AEV burner system. The basic design philosophy for the lifetime improvement is adapted from the well-proven GT24 and GT26 annular combustors. The liner segments represent Alstom’s proven technology of sealed TBC coated metallic combustor liners that can expand in their fixations. The application of a thermal barrier coating onto the segments is simple and cost-effective. The design is robust so that the liners have to be checked only at major inspections and are not subject to reconditioning/replacement at hot gas part inspections. The closed-loop cooling arrangement is used for the backside cooling of the hot gas liner segments and to maintain the large structural components at a constant temperature. This combustion segment improvement is combined with the AEV (Advanced EnVironmental) burner. All the mentioned features result in a marked improvement of the operating and cyclic lifetime of the GT13E2 combustor. This paper describes the development and validation process for the implementation of the combustion liner segment technology of the GT13E2. The various design phases from concept development to validation including the generic tests and final engine implementation are described and substantiated.
Designing a state-of-the-art combustor requires an iterative process where mechanical design solutions in the early concept phase are continuously assessed using analytical cooling and lifetime assessments, which are later backed up with experimental investigations and validation measures. This paper describes the integrated design process in terms of design, cooling, manufacturing, aerodynamic and mechanical integrity for the transition duct of the GT13E2 combustor, which houses the flame development region of the combustor. The objective was to develop a retrofit design with reduced lifecycle costs, with no impact on the combustor-turbine interface and no impact on the overall engine performance. The major challenges were the on-site welding of the two half-shells as well as the increasing demand for cyclic operation of the engine. During the development process, the focus was on selecting reliable and robust cooling schemes on the inner and outer shell to reduce mechanical deflections and thus to reduce the overall stress distribution. Key features of the GT13E2 combustor zone 2 are the following: • Drastically reduced lifecycle cost with no performance penalty (retrofit) • Separation planes at 3 and 9 o’clock position with mechanical locking connections (bridges) and a recess weld with film cooling • Bellmouth shaped inlet of cooling channel with improved impingement and convective cooling • Unique membrane seals with great mechanical flexibility around the turbine inlet outer diameter including mitigation against hot gas ingress (bow wave effect) • Improved cooling during transient conditions to reduce mechanical deflections • Reduced reconditioning effort due to innovative manufacturing methods The cooling schemes were successfully validated against laboratory experiments and integrated into a stable manufacturing process. Increased dimensional stability was achieved through higher rigidity and led to an improved on-site welding process for the separation planes. All the aforementioned features result in a marked improvement of the cyclic lifetime with no performance penalty. This is proven by the fact that the GT13E2 with annular combustor transition duct has now accumulated more than 30,000 operating hours with 1,200 starts.
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