POWER October 2010 - 29

TOP PLANTS
1. Corn belt. Discarded seed is blended daily with coal in the boiler house at the ADM
Clinton cogeneration plant. The facility has experienced some seed spillage around the conveyor
belt, but overall, the seed conveyance operation has performed better than expected.
Courtesy: ADM
Using Biomass for Fuel
" The plant uses Powder River Basin coal
and Illinois coal at an 80% and 20% blend, "
Duffy said. " We can burn up to 20% of alternative
fuels based on input Btu heat value.
The biomass waste stream from ADM's new
biodegradable plastics processing plant could
eventually make up 20% of the alternative
fuel once fully operational. "
There are many biomass fuels that have
potential, such as corn stover, switch grass,
wood products, and dried distillers' grains.
" Discarded seed is a very easy biofuel to
handle, and it is blended daily with the coal
in our boiler bunkers, " Duffy said (Figure 1).
Duffy described a number of unique issues
that the cogeneration plant faces related
to using biomass as a fuel source:
■ ADM must continue to monitor its operations
to see if additional maintenance on
the boilers is required due to the use of alternative
fuels.
■ Plant personnel have the daily challenge
of making appropriate adjustments to
accommodate an appropriate blend of
fuels, to mix the biomass fuel uniformly,
and to monitor the combustion process
accordingly.
a 75-MW generator, nine-stage, noncondensing
turbine and generator, and Unit 2
has a 105-MW generator, 14-stage, extraction-condensing
turbine and generator.
■ Three circulating fluidized bed (CFB)
boilers manufactured by Metso Power:
1,200,000 lb/hr steam at 1,310 psig and
900F.
■ One fuel storage dome manufactured by
Dome Technology: 298 feet in diameter
by 164 feet high and concrete-reinforced.
■ The stacker/reclaimer located inside the
dome was manufactured by MVT Materials
Handling GmbH: type CSST-24201375/90
with a 1,650-tph stackout rate and
a 950-tph reclaim rate.
" A complete standalone water-makeup facility
draws water from three wells to generate
high-purity boiler feedwater and cooling
tower makeup, " Duffy said. " The water is purified
using reverse osmosis and mixed bed
polishers. The water system cleans returned
condensate from the processing plants with
mixed bed resin polishers to increase overall
efficiency of the operations. "
Air Pollution Control Technologies
" We designed, built, and permitted with intentions
of burning up to 20% of alternative
fuels, " Duffy said. " We monitor these fuels
October 2010 | POWER
and make sure they will allow compliance
with our existing air permits. "
Because a large percentage of the fuel
mix used by the facility is coal, the plant
uses crushed limestone for sulfur dioxide
(SO2
trolling nitrogen oxides (NOx
) control, anhydrous ammonia for con),
and fabric
filter baghouses for particulate control.
Both fly ash and bottom ash are conveyed
from the boilers to ash storage silos via
pneumatic conveying.
Limestone is received by truck, conveyed
into storage silos, and conveyed from there
to individual day bunkers at each boiler.
Coal is received by rail and truck; conveyed
to covered dome storage; and then
reclaimed, crushed, and conveyed to individual
day bunkers at each boiler, as well. A
multiple-lined flue accommodates the three
boilers with a 412-foot-tall chimney.
The three CFB boilers started up with
a selective noncatalytic reduction system,
which was designed and supplied by
DNX Engineers for NOx
addition for SO2
control, sorbent
control, and reverse-air
baghouses for particulate control. The
technology helped the processing facility
and cogeneration facility reduce overall
SO2
emissions by 79% and its NOx
emissions
by 60% in 2009 compared to 2008
emissions.
www.powermag.com
■ The staff have the additional logistical
challenges of having to coordinate biomass
material delivery on a time-of-day
basis so as to not interfere with coal, lime,
and ash traffic at the plant.
Dedicated Operations Team
" We have a superb operations team in regards
to safety, housekeeping, and training,
and the team has great pride in the plant, "
Duffy said.
The average night and weekend operation
includes six operations personnel on
each of four shifts. In addition, there are
four material handlers on the Monday
through Friday day shift schedule who handle
the unloading of coal, lime, and biofuel,
as well as the loading out of ash. The plant
has a maintenance staff and instrumentation
and electrical staff of 13 employees.
All together, the total facility staff includes
53 ADM employees.
The ADM operations staff commissioned
the plant to make safety its top priority. They
have worked over three and a half years
without a recordable incident related to a
violation of the Occupational Safety and
Health Act. Plant employees, along with all
contracted staff, have adopted a values-based
safety observation program to help them realize
the ADM belief that " Zero is Possible "
when it comes to workplace injuries. ■
-Angela Neville, JD, is POWER's
senior editor.
29

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POWER October 2010

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