Rolls-Royce 1004227 - Manual (Page 21)

EPR Proprietary I Licensed Material
Introduction
1-5
− Multi-pass serpentine cooling schemes
− “Shower-head” cooling schemes
• Advanced materials
− Directionally solidified alloys
− Single crystal alloys*
− Low sulfur alloys*
• Advanced coatings
− TBCs*
− Oxidation coatings*
• Clearance and leakage control
− Passive
− Active*
− Abradable shrouds/labyrinth seals
− Brush seals
* Higher risk technologies
Independently Developed Technology Applied to Industrial Combustion Turbines:
Medium to High Risk
Some technological advances require independent design and development for the conditions
and environment the land based combustion turbines experience. The exhaust emission
requirement is a prime example where current regulations require NO
x
emissions below 25
ppmv, with an increasing number of locations requiring single digits. The aviation industry has
not yet addressed this challenge. The duty cycle of the aviation combustion turbine requires
take-off temperature for 150 to 300 hours total during its overhaul cycle (operational time to
depot repair) whereas the industrial land based turbine with DLE control, turndown
requirements, inlet heating, and ambient temperature could conceivably operate at continuous
rated power and rated firing temperature for the majority of its overhaul cycle. Since the time at
temperature constraint is greater for the industrial combustion turbine, the TBCs, oxidation
coatings, bond coatings, and materials must survive in a much harsher environment long-term
than the commercial aviation equivalent combustion turbine. Reliability and durability of this
technology is considered medium to high risk because much of the enabling technology has to be
developed and proven. Existing advanced systems are complex and have yet to be proven for
long term durability. Blades that have exotic coatings, in some cases, cannot be stripped and
recoated, thus are non-repairable and may not achieve full design life for the combustion turbine
design. This results in increased life cycle costs. Steam cooling for the combustion transition
pieces, vanes, and/or blades is being developed by manufacturer, university and DOE/ATS