pwr_july-2024 - 21

WATER AWARD
POWER POINTS
Winning Attributes
✔ Demonstrated an innovative
approach to utilize advanced
centrifugal separators to transform
heavy fuel oil sludge into reusable
resources.
✔ Significantly minimized
2. Epasa's sludge beneficiation system is the first worldwide to implement a complete GEA
Group system in a thermoelectric power plant, utilizing centrifugal separators for sludge beneficiation
and water purification. Courtesy: Epasa
Treating Sludge In-House
In 2019, Epasa's internal engineering departments
proposed an ambitious solution
to treat the sludge in-house. " The
pillars that we envisioned were to use
the sludge as much as possible in our
process, to treat the water in compliance
with the Brazilian environmental
legislation, and then to ensure, through
24/7 supervision, to treat the water, abiding
by legislative limits so that we could
return it to rivers. "
However, after researching solutions
by visiting sludge treatment facilities
globally, Epasa realized the solution did
not exist as a commercial offering. The
company then moved to contract a Brazilian
engineering company to help it design
a dedicated system that would cater
to the power plant's specific demands.
" The complete system would have required
integrating technologies from two
vendors, " Agra noted.
Following
engineering
discussions,
which lasted more than a year, Epasa convened
an in-house group of experts and
collaborated with GEA, which " opened a
window to change specific components
in their standard equipment " and adapt
the project to Epasa's needs. Under the
working solution, Epasa purchased a GEA
OSE 80 centrifugal separator to beneficiate
the sludge produced by the standard
GEA and Alfa centrifugal separators during
the purification of raw HFO. In addition,
Epasa integrated a GEA WSE 20
bilge separator to purify the oily water
before disposal (Figure 1).
Essentially, as Agra explained, the system
operates in two key stages. In the
first stage, the GEA OSE 80 centrifugal
separator, with an effective capacity of up
to 2,300 liters per hour and operating at a
separating temperature of 95C, beneficiates
the sludge. This de-watering process
July 2024 | POWER
efficiently separates the sludge into three
distinct outputs: water, which still contains
oil ranging from 5% to 30% by volume;
treated oil that Epasa could reuse as fuel;
and sludge residue, suitable for direct delivery
to industrial users such as cement
and ceramic industries. The initial mixture
entering the OSE 80 typically comprises
70% to 95% water and about 3% solid
content, highlighting its capacity to handle
high moisture content effectively.
The second stage involves the GEA
WSE 20 centrifugal separator, designed
to process up to 1,200 liters per hour at a
slightly lower temperature of 90C, which
focuses on de-oiling. This stage is crucial
for treating the oil-laden water produced
in the first stage through a combination
of filtration, coalescence, and separation
techniques. At this stage, the mixture
predominantly consists of water (99.8%
by volume) with a minimal oil content
of 0.1%. This ensures that the final discharged
water meets environmental
standards for disposal or potential reuse
in other processes.
The project, implemented in 2021 (Figure
2), immediately showed promising
outcomes, but after an extensive period
of monitoring and operating the treatment
system, Epasa's team identified an
opportunity to make improvements. " Initially,
the project aimed to obtain beneficiated
sludge with low moisture content to
be commercialized with added value, " the
company noted. " However, the product
obtained from treating the HFO sludge by
the GEA OSE 80 separator had a water
content well below 1%, and laboratory
tests showed that the product met HFO
specifications. Thus, whenever the product
was compatible with the fuel stored in
the storage tank, we directed the beneficiated
sludge for burning in our engines,
thereby reducing HFO consumption. "
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transportation and carbon emissions
by processing sludge onsite,
reflecting a strong environmental
stewardship.
✔ Ensured that treated water met
stringent environmental standards,
highlighting their commitment to
ecological protection.
✔ Optimized resource use by
recovering and reusing oil from
sludge, enhancing both economic
and environmental efficiency.
✔ Collaborated with technology
providers to customize a sludge
treatment system tailored to
specific operational needs,
showcasing adaptive innovation.
A Meaningful Project with More
Potential
According to Agra, the project has so
far helped Epasa reduce its HFO losses
from 2% to 0.2%. That alone has shown
some economic gains. " The payback
of the project could be less than three
years, though that would require full generation
for three years, which is not our
reality, " he said. In addition, the system
is attractive, given that installation of the
system was relatively straightforward,
he noted.
A short-lived challenge he highlighted
was that the system's integration
into the plant required a temporary halt
to operations. After that, implementing
the solution efficiently requires time to
adequately train plant personnel and
ensure that they can integrate the new
process into existing operations, he
said.
For Agra, a more significant lesson
rests in the experience it gained in pulling
together various experts to resolve
a longstanding problem. He suggested
that the solution now stands as a lucrative
business opportunity for Epasa. ■
-Sonal Patel is a senior
editor at POWER.
21

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