POWER June 2014 - 50

FUELS
bypass valve as well as replacement of the secondary
fuel oil pumps and installation of two
viscometers, various control valves, several
new flow meters, and various other valves. The
fuel supply piping arrangement also allowed
operators to quickly secure the palm oil supply
and return to 100% LSFO should the need
arise. HECO required the new supply system
to be a permanent installation controlled
by the plant's distributed control system and
designed and installed to meet National Fire
Protection Association guidelines.
Another important difference between biofuel
and LSFO is the biofuel's much lower viscosity
(~133 SSU for palm oil versus ~1,600
SSU for LSFO at 122F). This difference required
the fuel supply system to carefully
control fuel oil temperature as the blend ratio
of LSFO and biofuel changed during the testing
to maintain pump performance and good
oil atomization. The pour point of palm oil is
<80F. This means that fuel tanks holding palm
oil may require protective lined berms. LSFO
solidifies at ambient conditions.
The ash, sulfur, and fuel nitrogen contents
and carbon-hydrogen ratio of biofuel are
much lower than for LSFO. Consequently,
emissions of SO2
, particulate matter, NOx
,
and CO2 were expected to be lower than
when firing LSFO.
CCA Combustion Systems, a division
of Peerless Mfg. Co., was retained to perform
the baseline LSFO emissions tests,
develop the computational fluid dynamic
(CFD) model used to predict palm oil impacts
on boiler performance, and to design
and supply a unique atomizer that would allow
cofiring from 100% palm oil to 100%
LSFO with no loss in maximum load or
unit turndown capability (minimum load is
25 MW). CCA was also tasked with managing
the demonstration test, determining
boiler performance and plant heat rate, and
extrapolating the results of the demonstration
test to all HECO steam plants. HECO
performed NOx
emission tests following the
demonstration test.
Unique Atomizer Design
HECO contracted with CCA to design and
fabricate new mechanical, spill-return atomizer
assemblies for the biofuel demonstration
test. The design criteria for the new fuel atomizers
were ambitious:
■ Operate at approximately the same supply/
return pressures as the existing atomizers.
■ Have the same spray quality but not adversely
impact spray angle at low loads.
■ Must not inhibit full-load operations nor
Missing
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Later in the series a son, Guy Newcomen
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working with hard-boiled characters in the
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What Is Palm Oil?
Palm oil is a vegetable oil produced
from the red fruit of oil palms, each
about the size of a strawberry. The oil
is favored by the food industry because
of its relatively low cost and because it
is one of the few with highly saturated
vegetable fats. In fact, 65% of all vegetable
oil traded internationally is palm
oil. Indonesia and Malaysia produce
about 85% of the world's palm oil.
Palm oil is a recent entry into the
global biofuel market. Malaysia began
refining the tropical vegetable oil-
primarily used in consumer goods like
snack foods, soaps, and cosmetics-into
a biofuel and blends about 10% palm oil
with diesel fuel for use in automobiles.
Palm oil is semi-solid at room temperature.
Palm oil also has been used as a
fuel for biodiesel-fueled power plants in
various countries, including in Europe
and Asia.
Palm oil is considered by experts to
be carbon neutral because the oil is
merely returning carbon dioxide to the
atmosphere that was obtained earlier
through photosynthesis. However, some
environmental groups oppose the use
of palm oil biofuels because palm oil
plantations require deforestation, which
more than offsets the positive effects
as a carbon sink. The Roundtable on
Sustainable Palm Oil, established in
2004, publishes standards and certifies
the production of sustainable palm oil.
About 15% of the world's palm oil production
was certified as sustainable in
2013, as was the oil burned by HECO
during the demonstration project.
Since this demonstration test was
completed, the U.S. Environmental
Protection Agency has determined that
palm oil is a nonsustainable, renewable
fuel because expanding its production
will necessitate clearing virgin forests,
and palm husks generate methane, a
greenhouse gas.
impact unit turndown.
■ Operate with fuel blends from 100%
LSFO to 100% palm oil.
■ Must accommodate 14% more flow when
burning 100% palm oil due to lower heat
content.
Prior to the biofuel demonstration test the
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POWER June 2014

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