POWER October 2021 - 30

TOP PLANT
POWER POINTS
Winning Attributes
✔ Achieving a 29% savings in
auxiliary power consumption
through innovative projects.
✔ Making a determined effort to ramp
up efficiency and reliability despite
stiff market conditions.
✔ Leveraging plant staff knowledge
and experience to find opportunities
for impactful performance gains.
2. Prime Energia Colombia's Termoflores power plant comprises two units. Flores I is a 160MW
combined cycle gas turbine (CCGT) consisting of a Siemens W501D5 combustion turbine
and a Mitsubishi steam turbine. Flores IV, a larger unit of 450 MW, has two CCGTs: a Siemens
W501D5 and a W501FC gas turbine, plus a Siemens SST-700/900 steam turbine. Plant staff recently
implemented several improvements worthy of recognition that enhanced plant efficiency
and boosted overall station performance. Courtesy: Prime Energía
in internal energy consumption.
One project entailed changing out the
three air fan coolers fitted in the Flores IV
W501FC gas turbine hydrogen generator
(Figure 1). " These coolers had reached
the end of their lifecycle-they were 22
years old-after being exposed to high
levels of corrosion due to proximity to
the sea, " said Serje. After analyzing several
alternatives, plant staff decided to
change the technology from air fan coolers
to water coolers, taking advantage of
surplus water flow from the condenser
cooling system.
" So, what we did was to quit all the
glycol from the heat exchanger, get it
out, and put water from the cooling
tower that is available for the other system.
So, we are using the same water
to put through the generator and cool
the hydrogen, " he explained. Part of the
challenge was to replace the generator
glycol-based cooling system " without
adding new equipment, " Serje said.
Later, the team decided to pursue a
similar project to switch out two fans for
the lube oil system. " We decided to get
these fans and use the same water of the
cooling tower, and pass it through the plate
heat exchangers and cool the lube oil of the
gas turbine. " Currently, both systems are
fed with water from the CC cooling tower,
reusing two existing glycol pumps, he said.
Combined, the two projects led to the
dismantling of five motors, resulting in a
power savings of 85 kW. But they also
saved another 75 kW after improving the
operating point of the condenser cooling
system pump. In all, the solutions also
turned out to be money savers. Prime Ter30
moflores
(Figure 2) saved an estimated
$890,000 with the solution when compared
to having to replace the fan coolers.
pressors with a pair of 56-kW air-cooled
compressors. The solution resulted in a
power savings of 188 kW.
" That project taught us a valuable lesson
that other plants may learn from, " Serje
remarked. " Do an efficiency analysis to
understand a compressor's performance
because it's something you can't see. You
don't know what the compressor is doing
in the background to keep that pressure
" Do an efficiency analysis to understand a
compressor's performance because it's something
you can't see. You don't know what
the compressor is doing in the background
to keep that pressure. "
-Jose Serje, Termoflores plant manager
Crucially, they also avoided an extended
outage, which would have been detrimental
to the company's revenue. Plant
workers spent two months in the middle
of the pandemic building pipes and readying
structural components. " When we
were ready to do the connection to the
actual system, we stopped the unit and
made the connections. It took us only five
days, and it was done during a combustion
turbine planned outage, " Serje said.
Analysis Provides Visibility
Another project was inspired when consultant
Neumatica del Caribe's detailed
efficiency analysis showed the unit's two
150-kW instrument air compressors were
not as efficient as they could be, particularly
owing to their frequent starts and
stops. " What [the firm] suggested was
that a smaller compressor would be online
for more time, but the net efficiency
and power consumption would be less
than starting and stopping every time, "
Serje said. Plant staff ultimately decided
to replace the large water-cooled comwww.powermag.com
[with
frequent starts and stops] and taking
the pressure in low-loads. "
Plant workers, striving to maximize
their efficiency gains, also made several
smaller changes. One was to update
the electric substation and power plant
lighting using LED technology instead of
metal-halide lamps. That alone resulted
in a power savings of 18 kW. As remarkably,
by improving operating procedures,
workers found during one exercise that
Flores IV didn't need to use two circulating
pumps as intended by the designer
to operate at baseload. " We established
that one pump will be enough, " said Serje.
That resulted in an additional power
savings of 1.71 MW.
Put together, the plant's efforts to optimize
its auxiliary power consumption
reaped big gains. Serje said that while its
average auxiliary power consumption in
2011 was 10.26 MW, it is now 7.21 MW.
" That's a 29% savings in internal energy
consumption, " he said. ■
-Sonal Patel is a senior associate
editor at POWER.
POWER | October 2021

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POWER October 2021

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