POWER October 2014 - 57

COMBUSTION TURBINES
the TPM did improve the grid response of the
Morris plant and may allow the plant to move
into a grid response category with a higher
payment.
The competitive 2-MW gas-fired enginegenerator
could also be started, synchronized,
and at maximum load in less than the
10 minutes standard to supply grid regulation
power. But then again, a simple cycle Frame
7FA (227 MW) can start and reach 50% load
within 10 minutes and then ramp up at 40
MW/min. Aeroderivative engines start and
synchronize even faster.
Black Start Service. The TurboPHASE
has the potential to become an interesting
black start option for some utilities with
combined cycle plants. However, it's difficult
to compete with a diesel engine when
the weather gets very cold (see " Prepare Your
Gas Plant for Cold Weather Operations " in
this issue), particularly when natural gas
supplies are limited for power generation at
some gas plants. The best black start systems
will be an independent system that can supply
power to just the critical plant systems
needed for restart. On the other hand, a TPM
can be installed in two to three months while
a new engine-generator will likely take six
months or longer.
Final Analysis
TurboPHASE has the potential for reinvigorating
existing combined cycle or simple
cycle plants with additional peaking capacity,
especially during warmer days when the
output of the CT is otherwise limited. The
response of the TurboPHASE, from the limited
information we have reviewed, is on
the same order as a gas-fired reciprocating
engine. Efficiency leans toward the enginegenerator
because the combined cycle plant
has a higher heat rate. This balance point
could easily change should the TPM be installed
on a more efficient CT, although there
aren't many that CTs with a heat rate less
than 8,000 Btu/kWh (for example, the 60-Hz
7FA is 8,680 Btu/kWh).
On the other hand, the cost of a TPM is
likely less than a bank of centrifugal chillers
and coils that are often used to increase
CT power output during warm weather. Also,
since the TPM produces compressed air at
300 psi, the system can be used on any CT
with a compressor discharge pressure of 290
psi or less, which includes many E-, F-, and
G-class CTs and some aeroderivative engines,
assuming there is a suitable open port
on the casing at the compressor discharge.
The response of the TurboPHASE does
meet the PJM requirements for grid regulation
power but only when the unit is running
and the compressor is charged and ready to
dump compressed air into the CT. A potential
owner must consider the economics of
balancing the regulation payments from PJM
against the cost of the TPM and the added
fuel costs. Also, it probably goes without
saying that potential adopters must be located
within an RTO that has a grid fast regulation
payment scheme.
What do the OEMs think about an owner
adding compressed air into the engine casing
for peaking power or fast regulation
purposes? General Electric's GER-3567H
states, " GE [heavy duty] gas turbines are designed
to allow up to 5% of the compressor
airflow for steam injection to the combustor
and compressor discharge. " If superheated
steam injection is acceptable to GE, as it has
been for over 30 years, then one would expect
that compressed air in like mass flow
will also be acceptable. Also, it seems to me
that injecting clean compressed air upstream
of the combustor is certainly preferable to
wet compression resulting from the use of
evaporative coolers. ■
-Dr. Robert Peltier, PE is POWER's
consulting editor.
2014
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POWER October 2014

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