March (pdf) - New York Power Authority

March 29, 2011
5. RM Flynn Power Plant 2011 Major Outage –
Capital Expenditure Authorization Request
SUMMARY
The President and Chief Executive Officer submitted the following report:
“The Trustees are requested to approve capital expenditures of $7.195 million for projects associated with
the 2011 RM Flynn Power Plant’s (‘Flynn’) major outage and subsequent replacement or upgrade of critical parts
for the RM Flynn gas turbine.
BACKGROUND
“In accordance with the Authority’s Expenditure Authorization Procedures, Trustees’ approval is required
for capital expenditures in excess of $3 million.
“Flynn has been in service since May 1994. The plant consists of gas turbine and steam turbine. The
timing of major overhauls and large projects at the plant is based on the recommended maintenance cycles of the
Siemens V84.2 gas turbine. Siemens recommends that the gas turbine be completely overhauled and upgraded
approximately every 33,000 operating hours, which is once every four years. When the plant is shutdown, other
projects which cannot be done while the plant is in service are completed. Flynn’s major outages were completed in
1996, 1999, 2003 and 2007. The next major outage is scheduled for October and November 2011. The projects
described in the discussion section below are crucial to the safe, reliable and efficient operation of the plant.
DISCUSSION
“The Siemens V84.2 gas turbine has two large mixing elbows that are in the hot gas path section which
direct the combustion gases to the turbine section. The mixing elbows that will be removed in 2011 have been in
service for approximately 100,000 hours and are the end of their useful life. New mixing elbows will be purchased
for inventory.
“The gas turbine industry in general and Siemens specifically, have determined that the material used to
make the blade wheel in stage 4 of the turbine becomes brittle over time and may fracture under certain conditions.
If the disc fails to pass Non Destructive Examinations (‘NDE’) it will be declared unusable. Published lead time for
this part is over one year. Flynn staff has determined that the safe and prudent action is to replace the disc. The disc
in service will have approximately 150,000 operating hours at the time of the 2011 major outage.
“If compressor blades or diaphragms fail in service, it usually causes severe damage to the turbine. All of
Flynn’s seventeen compressor stages are original and running well beyond the 100,000 hours, the time in which
Siemens recommends replacement. Based on fleet history, Siemens has identified certain stages that are more prone
to failure. Using Siemens’ recommendations, Flynn staff has selected stages 2, 4 and 7 for replacement in 2011.
“Flynn’s gas turbine generator has six lead bushings which connect the generator output to the transmission
system. Some have had component failures related to vibrations. Certain failures have the potential to damage the
generator. Flynn staff thinks it is prudent to replace the bushings in 2011.
“During the 2007 outage, divided seal rings were identified as worn; staff recommends that they be
replaced in 2011.
“At the 2011 major outage, the turbine’s stage 3 blades and stage 2 vanes will be at the end of their useful
life. New blades and vanes will be purchased for inventory.
“The Siemens V84.2 gas turbine has two distinct burner decks each of which has six burners. Each deck
has four control valves for fuel gas and fuel oil. The actuators for these valves have typically required frequent
maintenance and have the potential to fail in ways that damage the gas turbine. Siemens has developed actuators
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