POWER August 2010 - 31

2010 PLANT OF THE YEAR
5. Removing mercury. The air quality control systems are essentially identical between
the units. Particulates are removed with a modern baghouse equipped with tens of thousands
of fabric filter bags, each more than 30 feet long. The baghouses are located between the SCRs
(in the background) and the wet scrubbers (one of the two wet scrubbers is shown in the right
foreground). An activated carbon injection system is used to reduce mercury emissions-another
first for a lignite-fired plant in the U.S. Courtesy: Luminant, photo by Allison V. Smith
6. Digitally detailed. Fluor is well known
for pushing the plant digital control envelope.
Fluor worked closely with Foxboro, Invensys
Operations Management to design a state-ofthe-art
control system. General Electric supplied
its Mark VI digital control packages to
manage each of the two steam turbines used
on the project. Courtesy: Luminant, photo by
Allison V. Smith
Thompson also pointed out another measure of
the project's success: Unit 1 was built in only
30 months and Unit 2 in 35 months after notice
to proceed was received from Luminant.
Four primary teams contributed to the success
of the project: Luminant Construction
(responsible for developing and administering
the EPC contract), Luminant Operations
(responsible for hiring and training of plant
staff and providing workforce for commissioning),
Fluor Construction (responsible for
plant construction activities), and Fluor Commissioning
(responsible for commissioning
equipment to meet contract guarantees).
With the necessary construction permits
and a well-defined EPC contract in hand, Luminant
broke ground on the 1,600-MW Oak
Grove Power Plant on June 14, 2007.
Plant Design Features
Oak Grove's new air emissions permit required
Fluor to select an AQCS that complied
with best available control technology for controlling
emissions when burning lignite. To do
so, Luminant and Fluor upgraded the existing
supercritical boiler furnaces with low-NOx
burners and overfire air ports and then added
a selective catalytic reduction (SCR) system
to the steam generator. Oak Grove is the first
plant in the U.S. that has installed SCR on a
100% lignite-burning power plant.
The boiler upgrade work was actually two
separate projects, as the two supercritical
steam generators use remarkably different design
philosophies: Alstom Power uses a tilting
corner-fired design whereas B&W uses wallfired
burners.
James Brown, Fluor's director of engineering,
reflected on the unique opportunity that
this project afforded Fluor: " Fluor's strength
August 2010 | POWER
as an EPC contractor is that we can effectively
evaluate different technologies, from technical
aspects, constructability, commissioning,
and operation. This evaluation typically takes
place in a hypothetical manner on paper based
on experience of the technologies at various
sites under varying conditions. The Oak
Grove project has provided real-life side-byside
comparisons of the design, construction,
commissioning, and operation of these two
technologies. They are very different steam
generator technologies incorporating different
erection approaches and commissioning techniques
with similar end results. "
The AQCS systems were essentially identical
between the plants, such as the wet flue
gas desulfurization system. Particulates were
removed by an ESP in the original design, but
that equipment was discarded and replaced
with a modern baghouse equipped with tens of
thousands of fabric filter bags, each more than
30 feet long because of the plant's very tight
particulate limits. An activated carbon injection
(ACI) system is in place in accordance with Luminant's
fleetwide program to reduce mercury
emissions from its coal-fired plants, another first
for a lignite-fired plant in the U.S. (Figure 5).
Upgraded boilers meant upgraded controls
and instrumentation, another replicated
design task. Parallel projects were required
given the significant differences in boiler
control logic philosophy, including two separate
factory acceptance tests. Watson noted
that although the operator interface in the two
units' control rooms appear identical, there
are many nuances that require separate operator
training on each unit.
Another modern development is the
plant's suite of continuous air emissions
monitors that measure and log NOx
, SO2
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,
ammonia slip, CO, and particulate matter. A
continuous mercury monitor also was added
to each unit to monitor performance of the
ACI system. Watson noted that the care and
calibration of these monitoring system keeps
several technicians busy full time.
When the original units were designed in
the mid-1970s, analog and pneumatic controls
were customary. Today, advanced digital
control systems (DCS) and electronic sensors
are de rigueur, and Fluor didn't disappoint.
Fluor's controls engineers are well known for
pushing the envelope in power plant digital
system design.
POWER recognized Newmont Mining's
200-MW TS Power Plant as a Top Plant in
our October 2008 issue for featuring " perhaps
the most advanced digital bus technologies
framework ever installed at a power
plant and [using] these technologies to the
maximum extent possible. " POWER editors
were so impressed with TS Power's DCS design
that a more in-depth article followed a
year later ( " Digital Networks Prove Reliable,
Reduce Costs, " July 2009). In that article we
wrote that the " TS Power Plant is perhaps
the power industry's best example of how a
plantwide digital controls architecture can
provide exceptional reliability and be significantly
less costly to install. "
There isn't space in this article to discuss
the details of the Oak Grove controls design,
but suffice it to say that Fluor leveraged the
lessons learned on TS Power to further push
the digital controls envelope at Oak Grove,
especially in the areas of using digital controls
in the balance of plant and the electrical
switchgear, down to the 480V motor control
centers. Foxboro, Invensys Operations Management
supplied the DCS equipment (Fig31

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POWER August 2010

Table of Contents for the Digital Edition of POWER August 2010