POWER October 2014 - 56

COMBUSTION TURBINES
3. Day one tests. Results of the first day of TurboPHASE demonstration tests are illustrated.
The blue line represents the temperature at the inlet to the combustion turbine. The orange
line shows the response of the combined cycle plant to full air injection. Courtesy: PowerPhase
LLC
■ CT1 MW ■ CT1 inlet temperature
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Time
The piping system pressure drop between
the TPMs and the CT was ~11 psi with one
TPM operating (flowing 11.5 lb/sec) rising
to ~40 psi with two TPMs operating, so the
airflow into the CT was slightly less than
double (22 lb/sec). The pressure drop effect
is apparent in Figure 4 where a single TPM
produces ~3 MW while two TPMs produce
slightly under ~6 MW. A line size increase
from 6 inches to 8 inches would solve this
problem, but since Morris doesn't anticipate
operating the plant in this manner, the cost of
the pipe size increase isn't justified.
Pluses and Minuses
Before assessing the results of the testing, it's
best to remember that this was the first fullscale
demonstration test of the TurboPHASE
and we were privy to only an overview of
the testing and the performance results. That
said, we are still able to reflect on the performance
of the system in relation to the important
ancillary services PJM and other RTOs
desire: synchronized reserve, fast grid regulation,
and black start service.
Synchronized Reserve. A single TPM
consists of a single MTU gas-fired engine that
will produce 2 MW were it fitted with a generator
and operated standalone, which is the
obvious competitor to the TurboPHASE system.
Further, according to data on the MTU
website, this model gas engine with a generator
operates at a heat rate of ~8,000 Btu/
kWh, which is a very efficient engine, and
4. Day two tests. The test results of the second day of TurboPHASE demonstration tests
are illustrated. The last test of the day was with both TurboPHASE systems in operation followed
by a trip of one system. Courtesy: PowerPhase LLC
■ CT1 MW ■ CT1 inlet temperature
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2:30:00
TPM2 air
compressor trip
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Time
www.powermag.com
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more efficient than the CT. This class engine,
in " hot start conditions " (usually defined as
lubricating oil preheated, engine bearing prelubricated,
and cooling water preheated) can
be started and synchronized to the grid in ~60
seconds or less and reach full load in ~90 to
180 seconds. The downside is the extra cost
of the generator and switchgear.
The 60-second response of the TPM is
based on the engine operating at 75% load
with compressed air bypassing the CT. A
" start " signal puts the compressed air into
the CT and increased power is achieved in
~60 seconds in the CT, about 2.75 MW. The
capacitance in the HRSG and steam turbine
system brings the remaining ~0.25 MW along
well after the 60-second goal. Although the
data provided did not state the time period,
the two figures are suggestive that the time
lag is several minutes, as one would expect.
The report suggested that the average incremental
heat rate of the TPM (8,650 Btu/
kWh predicted) was 8,495 Btu/kWh based
on the full ~3 MW power increase. However,
the fuel flow data taken from station instruments
showed significant variation, so it's
best to consider the incremental heat rate as
anecdotal rather than a hard number. Also,
for comparison purposes, a more appropriate
incremental heat rate should be based on
the CT output alone rather than the CT plus
steam turbine output because of the severalminute
time lag of the steam system.
How does the TurboPHASE stack up
against using the same engine in a standby
package for synchronized reserve power?
Both packages must be running, in standby
mode, and synchronized to the grid to
qualify. However, the engine-generator
can be synchronized, kept at minimum
load (lower fuel consumption), and can
take on 2 MW of load within ~30 seconds
or so. The TPM must also be running but
held at 75% load in order to add 2.75 MW
to the grid within 60 seconds, but it does
so at a higher heat rate than the enginegenerator
alone. The economics are very
CT and site specific.
Fast Grid Regulation. Once the TurboPHASE
is operating, then its response to rapid
changes in grid demand must be considered.
Although the specific data wasn't available,
the TPM response to a step increase in load
demand can be estimated from Figures 3 and
4. The data does confirm that TurboPHASE
responds quickly, with the nearly vertical
lines representing the CT response followed
by the slower steam turbine. The data also
shows the CT responds in about 2 to 3 minutes,
with the additional steam turbine power
available within 10 minutes. The standard
PJM response requirement for grid regulation
power is 10 minutes. Regardless, adding
POWER | October 2014
CT1 (MW)
CT1 (MW)
TPM1 full injection
No injection
TPM full injection
TPM1 full injection
No injection
TPM1 full injection
TPM full injection
No injection
No injection
No injection
TPM1 & TPM2 full injection
TPM full injection
CT1 inlet temperature (F)
CT1 inlet temperature (F)

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POWER October 2014

Table of Contents for the Digital Edition of POWER October 2014