Manufacturers of Industrial Gas Turbines (IGT)
are applying Additive Manufacturing in multiple applications.
Traditionally AM technologies such as Vat-photopolymerisation and Binder-jetting were used
to create patterns and molds for casting turbine hot gas path components. This technologies
are still getting applied but increasing productivity and repeat ability of direct metal technologies
are changing the industry. Selective Laser Melting / Direct Metal Laser Sintering and Electron Beam Melting
are changing the design of parts and so the production, repair and overhaul processes.
Components of gas turbines for power generation are significant larger in size compared to the ones of jet engines.
But the thermal and mechanical loads on the components are very similar. The hot gas path components also require
the use of high temperature stable materials. This materials are nickel-base alloys, so called Super Alloys, very hard to machine, especially with conventional (substractive) machining.
Additive Manufacturing technologies allow completely new design approaches. Thin walled components with internal cooling channels and turbolators, to reduce the consumption cooling air, allow to operate the turbine at higher temperatures and increase their efficiency.
But in IGT the size and volume of the components can be challenging. Large compontes oftentimes means high builds,
high builds means higher risk of failure. But the advantages regarding efficiency and cost saving potentials are outweighing the challenge to overcome this hurdles. A closer look at patent databases unveil a real arms-race of the global players in power industry.
This part, seen at the RAPID Expo in Long Beach in May 2015, is a mock-up of an instrumented vane.
Sensors and can be attached to the vane to measure temperatures and pressures over the radius of the turbine.
This part demonstrates what intricate design feature are possible to realize with direct metal technologies.
Applications of AM in Power industry
Hybrid build up to recondition fuel burners
Siemens in Sweden is using Direct Metal Laser Sintering to recondition burners of Industrial Gas Turbines.
This technique reduces high skilled labor and reduces the chance of human error.
But Siemens is using direct metal AM technologies also for further applications as this video shows:
AM in Power Industry | Reconditioning & Repair
Further advantages of using AM
Components can be upgraded with new design features for performance enhancements.
Especially when it comes to the reconditioning of turbine blades, powder bed based direct metal technologies
can offer great advantages.
Cast blades are very unique in their geometry. Core shift during the casting process and deformation through
creep during operation are making this parts unique as human bones. But If the machine data is generated based
on a scan of the component, the part can be repaired individually in an automated process. The blade is mounted
in the machine bed and the SLM process starts on the component, rebuilding the section removed before.
Custom tailored repair patches
But a damaged sections of a component does not certainly need to be build up directly on the part.
Replacements can be build separately and joined with the component in a following step.
See this patent from ALSTOM explaining this technique in detail.
Larger components are usually welded together, forged or cast. This video shows a large footprint
Binder Infusion system that can be used to create casting patterns such as molds & cores additively: