Design and Validation of an Improved Lower Emission Additively Manufactured Combustor Pilot Nozzle for F Class Industrial Gas Turbine

Abstract

Emerging additive manufacturing technology offers many opportunities for improved design in gas turbine components by enabling optimization of parts that are not manufacturable with conventional methods. The combustion components, for example, require complex fuel and air circuits to achieve best possible mixing and oxidation process for the lowest emissions possible. Thanks to the additive manufacturing, new combustor parts are making a break thru for improved capabilities in fuel flexibility and operating conditions. Also, quick turn around and modularity makes additive manufacturing a key enabler for fast validation of design concepts. This paper describes the application of additive manufacturing technology in an F class industrial gas turbine including design, development and validation steps of a combustor pilot nozzle. A systematic design approach was undertaken to examine all aspects of combustion operation and testing, down-selecting the appropriate design, material and to productionize. Experience gained from other additive manufactured production parts as well as testing coupons were leveraged to ensure a robust production process. Combustion atmospheric rig testing was conducted to validate emissions performance. Detailed thermal and structural analyses were performed and validated with testing experience. The new design demonstrated a benefit of approximately 50% in start-up emissions as well as improved combustion stability. In addition to the operability benefits, a 50% reduction in cost of the production assembly was realized. A main cost advantage gained with the utilization of additive manufacturing was the reduction in part quantity from 7 individual components down to 1. Constraints typical of conventional manufacturing methods were avoided with the implementation of innovative geometries only achievable by additive manufacturing. In addition to combustor component reduction, the additive process was also leveraged to reduce the total number of fuel circuits in the combustion system, making the installation and control logic more straightforward. Several sets were successfully installed in customer’s engines, benefiting from an improved combustor pilot nozzle. Detail of the design and development steps as well as the results of combustion tests are presented and discussed in this paper. It shows that with proper considerations of the additive manufacturing technology, very quick turn-around and implementation of improved combustions solutions can be achieved: less than a year from development to production.