By Melissa Fassbender, Associate Editor, PD&D
Excel Energy’s French Island plant is a combination generating plant and resource recovery facility. By working together, the two facilities generated
over 88,500 MWH of electricity in 2012
– enough to power nearly 10,000 homes.
Originally built in the 1940s as a coal-fired
generating facility, French Island has a long
history, and many of its original parts still
remain in operation today.
“We change a lot of the equipment and
redesign it, but we don’t put in new equipment. This technology works for us,” plant
manager Mark Paitl explains. But with a
facility that is more than 70 years old, regular maintenance, quality machinery, and
updates in technology are
vital to keep the plant
like this would
not be in
says. To stay
coal to oil in
1972, and then to
waste wood in the
early 1980s. Currently,
the plant’s two generating units burn wood
waste, railroad ties, and
solid waste called refuse-derived fuel (RDF).
in is processed into fuel, residue, or metals that are recycled, and then we start
over the next day,” says Paitl. The process
begins on the tipping floor where the solid
waste is dumped and sorted. A front end
loader removes oversized items and feeds
the remaining waste into a flail mill that
“busts everything up.” The flail mill consists of 45 hammers that weigh 35 pounds
each, rotating at 800 rpm.
After the hammers have broken down
some of the larger content, a magnetic
separator removes any ferrous material.
“Even after recycling, we are collecting
about one ton of aluminum cans per day in
the garbage we receive,” Paitl adds.
Materials four inches and smaller are
further separated as they pass over
a disc screen. These pieces go
directly to the fuel loop and
the rest are shredded into
RDF and stored until they
are needed. Blow lines
transport the RDF to the
boilers where it is burned along with wood
received from area vendors. The fluidized
bed boilers produce superheated steam at
450-pounds per square inch at 750°F. The
steam goes directly to the two steam tur-
bine generators, both capable of producing
15 megawatts of electricity.
To keep the plant running smoothly,
engineers rely on a system of controls.
Before their latest upgrades, the plant was
using the Bailey Net 90 control system,
which was very centralized. In their process of upgrades to comply with municipal waste combustor regulations, the
company saw the opportunity to decentralize the system and add a new control
room, according to Dave Hendrickson, the
Every day, garbage
trucks from around La
Crosse, WI bring their
loads to the facility
where it is inspected
and processed into RDF.
“Everything that comes