POWER January 2014 - 63

PRBCUG AWARDS
OPPD's North Omaha Station Takes
PRBCUG Honors
The Omaha Public Power District (OPPD), one of the largest publicly owned utilities
in the U.S., generates approximately one-half of its electricity by burning coal.
OPPD's North Omaha Station began using low-sulfur coal from Wyoming's
Powder River Basin in 1985. Plant upgrades that increased plant safety and
the reliability of plant operations were recently recognized by the PRBCUG with
its 2013 Plant of the Year award.
By Dr. Robert Peltier, PE
T
he Powder River Basin Coal Users'
Group (PRBCUG) each year since 2000
honors one or two plants that burn PRB
coal for " innovation and implementation of
best practices and continual improvements in
areas including safety, environmental performance,
coal handling, boiler combustion, and
risk management. " In addition to Plant of the
Year honors, the selected plant is also inducted
into the PRBCUG Power Plant Hall of Fame.
For 2013, the Plant of the Year (Small
Plant Category) honors were garnered by
Omaha Public Power District's (OPPD)
North Omaha Station (NOS). The trophy presentation
and recognition for the outstanding
work by the plant staff took place during the
May 2013 ELECTRIC POWER Conference
& Exhibition, the venue for the annual meet1.
The first team. Representatives of OPPD's
North Omaha Station plant staff received
the coveted PRBCUG Plant of the Year Award
(Small Plant Category) at the past annual PRBCUG
conference, held jointly with the ELECTRIC
POWER Conference & Exhibition. From
left to right, David Wetrosky, Plant Manager,
OPPD; David Wilson, Yard Equipment Operator,
OPPD; Randy Rahm, Executive Director,
PRBCUG; Pat Baker, Crew Leader, OPPD;
John Bridson, Chairman, PRBCUG; Kirk Estee,
Operations Superintendent, OPPD; William
Konefes, Vice Chairman, PRBCUG; Brian
Langel, Manager-Production Engineering,
OPPD and Greg Krieser, Division Manager,
OPPD Source: POWER
ing of the PRBCUG (Figure 1). The Plant of
the Year (Large Plant Category) award was
presented to TransAlta's Centralia Generation
Plant (see p. 62). Additional information
about the PRBCUG, its 2014 annual meeting,
and the group's awards program is available
at www.prbcoals.com.
The North Omaha Station consists of five
units with a combined capacity of 625 MW
and is part of the 3,200-MW OPPD system.
The last unit entered commercial operation
in 1968, 14 years after the first unit was constructed.
NOS was originally designed to combust
Midwestern high-sulfur coal. In 1985, the
attractive environmental advantages and costeffectiveness
of PRB coal resulted in the decision
to transition the station to the low-sulfur
coal. The lower heat content and higher ash
content of the subbituminous coal meant that
the coal burn rate would have to increase in
order to deliver the same fuel energy content
compared to bituminous coal, although the
plant was not derated as has occurred at other
plants. In addition, the entire fuel system-
from unloading on the coal pile through the
burner tip-required upgrades in equipment,
2. Making the switch. OPPD's North
Omaha Station is composed of five units producing
a total of 625 MW. The fifth unit was
installed in 1968, the first unit 14 years earlier.
The plant made the switch to PRB coal in
1985 and finished a complete upgrade of the
plant's fuel-handling systems in 2012. Courtesy:
OPPD
plant operating processes, and additional
training of the plant staff. Safe combustion of
PRB coal is an intentional process. The 105person
staff of NOS joined in the common
goal to become a leader in safe handling and
combustion of PRB coal (Figure 2).
A few years ago, NOS decided it was time
to upgrade the antiquated material-handling
system to improve safety and plant reliability.
NOS partnered with Martin Engineering to
perform a safety and equipment audit that recommended
cost-effective equipment upgrades
to simultaneously improve plant operational
reliability and reduce coal fugitive emissions, a
key safety challenge when burning PRB coal.
After a series of discussions, OPPD developed
a four-phase material-handling improvement
program. The first equipment
upgrade phase began in October 2009, and all
four phases were completed in 2012. Specifically,
the material handling upgrade program
included equipment changes and upgrades in
the Shaker House, where the coal is unloaded
from rail cars; the Crusher House, which receives
and processes the coal received from
the Shaker House; the Transfer House; the
Tripper Room, which feeds the coal to the individual
boiler fuel silos; and all the conveyors
that interconnect the plant (Figure 3).
The coal dust management program entailed
rebuilding all the plant's coal-handling
transfer points including all vulcanized splices
in the conveyor system, impact beds, and
belt supports. In addition, improved equipment
was added or replaced existing, such as
taller chute walls, new apron seals, and dual
dust curtains. All the original roller bearings
on the conveying systems were replaced with
sealed roller bearings. Winged tail pulleys
were replaced with smooth tail pulleys, and
return plows and belt trainers were added.
Also, problematic contacting flow switches
used on the conveying systems were replaced
with noncontacting sensors.
January 2014 | POWER
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POWER January 2014

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