POWER June 2011 - 54

GAS TURBINE DESIGN
The T-Point Plant: The Ultimate
Validation Test
Fourteen years ago, the MHI T-Point demonstration combined-cycle plant in
Takasago, Japan, changed the way modern gas turbines are validated
under real operating conditions. In February, T-Point marked yet another
milestone by starting to validate the world's largest and highest efficiency
gas turbine, which operates at the unprecedented turbine inlet temperature
of 1,600C.
By Angela Neville, JD
U
ntil the 1990s, gas turbine prototypes
were shop-tested and validated at
" beta " sites where commercial power
production was typically hampered by issues
associated with the introduction of new technologies.
In order to optimize the process of
detecting and correcting defects during the
validation phase, and to prevent exposing
clients to the debugging process, Mitsubishi
Heavy Industries Ltd. (MHI) introduced the
concept of in-house validation under real operating
conditions.
The plants providing this service are operated
and maintained by MHI staff and sell
their electrical output to local utility companies.
Carlos Koeneke, vice president, project
engineering at Mitsubishi Power Systems
Americas Inc., told POWER in April that
MHI built the first 50-Hz validation plant, KPoint,
in Kanazawa in 1992. It was followed
in 1997 by a 60-Hz counterpart in Takasago,
called T-Point (Figure 1).
" These demonstration plants were the
first of their kind and revolutionized the
way validation of advanced gas turbines is
performed, " Koeneke said. " K-Point plant
was decommissioned several years ago, but
T-Point plant continues selling the generated
power and even today, 14 years after T-Point
went commercial, there is no other company
that performs the comprehensive validation
that the T-Point plant provides. "
The highest cost of sustained long-term
validation under real operating conditions
is not the equipment but the fuel consumed.
The T-Point plant is maintained and operated
by MHI under dispatch instructions from the
local utility (Kansai Electric). The plant is
frequently started and stopped, and every single
MW is sold under a contract, as with any
other independent power producer. Koeneke
explained that this arrangement " makes it
possible, from the economic point of view, to
sustain long-term validation operation. "
54
1. Carrying its own financial weight. The T-Point combined-cycle plant is maintained
and operated by MHI under dispatch instructions from the local utility, Kansai Electric. The plant
is frequently started and stopped, and every single MW of generated electricity is sold under
a contract. This makes it economically possible to sustain long-term validation operation. Courtesy:
Mitsubishi Heavy Industries Ltd. (MHI)
A Strong Track Record
In addition to revolutionizing the way modern
industrial gas turbines are validated,
in 1997 the T-Point plant pioneered the introduction
of steam cooling to gas turbines.
Through extensive validation of the steamcooled
M501G gas turbine, as well as the
upgraded M501G1 gas turbine in 2003, the
T-Point plant delivered excellent results that
facilitated deployment of the largest and most
successful steam-cooled fleet of gas turbines
in the market. To date, 47 units in operation
have logged in excess of one million actual
hours and 11,600 starts. This impressive GSeries
record culminated with the introduction
of the air-cooled version, which also was
validated since 2009.
Operating and maintaining the demonstration
plants in the same facility where
design and manufacturing occurs (the MHI
Takasago Machinery Works, which also includes
a rheostat shop test facility that can
www.powermag.com
be used to test off-frequency conditions)
results in a smooth debugging process with
a lower risk of failures and quick recovery
after unforeseen issues, Koeneke explained.
The validation process would not be representative
of real operating conditions if the
running modes were not determined by a real
demand condition or if the duration of the
validation run were restricted to only a few
hundred hours due to the high cost of fuel.
The T-Point plant has logged more than 2,300
start-stop cycles, 1,300 of those correspond
to daily operating cycles. It has also operated
more than 420 days, either continuously or
under weekly start/stop cycles.
" Because of the lower failure and interruption
risks, this demonstration concept
is widely praised by the insurance community, "
Koeneke said. " The testing scope goes
beyond the gas turbine. T-Point also has allowed
testing of a number of innovations,
including steam turbine upgrades, air-cooled
POWER | June 2011

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POWER June 2011

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