POWER July 2015 - 62

PRBCUG PLANT OF THE YEAR
burn PRB coal, HGS has no particular problems
with combustion. Slagging is not a significant
issue, and load reductions to remove
slag are not required. Each unit uses an intelligent
sootblowing system to keep the boilers
clean while avoiding unnecessary boiler tube
erosion. A Neuco Inc. neural network system
is used for combustion optimization, and it
has reduced the amount of sootblower operation.
New burner tips have been installed on
all three units to more efficiently burn the
low-sulfur coal.
Each unit is configured with five 600-ton
silos (bunkers), delivered from a parallel
conveyor and crushing system consisting of
32 transfer points, 18 conveyors, 14 feeders,
and two crushers. The silos are emptied as
a safety consideration during any planned
outages that are five or more days in length.
If the outage is unplanned, there is a written
silo management procedure for operators,
which requires CO monitoring during stagnant
bunker times, thermal gun readings once
per shift after five stagnant days, and manually
emptying bunker and returning coal to
the coal pile after 10 stagnant days. HGS has
adopted the PRBCUG's Best Practice for
Bunker/Silo Fire Protection.
Mastering the ABCs
Strong environmental consciousness is expected
of all power generation facilities, so
merely doing what is expected doesn't earn
PoY recognition. The PRBCUG reviewers
were also looking for evidence of operations
excellence and use of safety best practices, all
of which were evident at HGS. According to
HGS Plant Director Dennis Buchanan, HGS
is successful because its employees have
mastered the basics, the ABCs. According to
Buchanan, success is About Being Conscientious,
Clean, and Collaborative.
About Being Conscientious. Buchanan
views a conscientious staff as employees
who are focused on three important issues:
environmental excellence, personal and
equipment safety systems/processes, and
customer satisfaction.
For example, the HGS water recycling
program has had a significant positive impact
on regional water supplies, which is an
important issue in the semiarid region of the
Texas Panhandle. With Xcel Energy's nearby
Nichols Station natural gas-fired plant, ~15
million gallons per day of recycled water
(treated sewage plant effluent) from the City
of Amarillo is used for cooling tower makeup
water. Also, the plant wastewater has been repurposed
as irrigation for grasses, seed crops,
and forage on local farms. HGS is a zerodischarge
plant, and no wastewater discharge
leaves the plant property.
Also, all of the ash collected by the units is
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POWER | July 2015
sold for reuse for road fill, construction, and
other beneficial uses. None of the ash goes
to a landfill.
HGS has a spectrum of safety programs that
are organized locally (Partnership for Safety-plant
teams), regionally (Regional Safety
Committees), and corporately (National Safety
Committee). The Xcel Energy " Journey to
Zero " program encourages successful ideas
and programs to be quickly disseminated to
all Xcel Energy plant safety leaders. A PRBCUG
inspector noted, " The safety culture at
this facility is outstanding. Regardless of who
the employer may be, each worker receives
the same message from all levels within. That
message is the importance to go home safely
every day and to apply the safe work practices
used at work to what one does off the job. An
employee driven safety and health process including
the unique Safety Specialist approach
of Savage Services to behavior based safety
observations, to the Stop Work Responsibilities
of each person on-site. "
Limiting fugitive dust and CO monitoring
are critical safety functions at PRB-burning
plants. HGS, through its Combustible Dust
Control Program, has steadily reduced fugitive
dust throughout the coal-handling
process by incremental improvements in its
dust containment, suppression, and collection
equipment and processes as well as by
implementing industry best practices. The
preferred method for the collection and suppression
of coal dust in the plant and fuel
yards remains wetting using a water wagon,
as required by the air permit. Water is also
used during the unloading process on the
trestle. No surfactant is added to the water.
A number of upgrades are also under way
in the coal-handling systems, such as transition
from square to round baghouses, tramp
metal magnet replacement/upgrades, and
passive dust control measures throughout the
facility. Mobile equipment moving coal is
equipped with fire detection and suppression
in readiness to protect the operator and the
equipment from various fire scenarios such
as fuel or hydraulic oil line failure, coal-related,
or other fire developments.
Fire detection and suppression systems in
the fuel-handling system were recently upgraded
and monitored so that prompt detection
of a developing problem is recognized
and acted upon. In the words of one of the
PRBCUG inspectors, " The 'home grown'
dust suppression system was designed, installed,
and works amazingly well. "
The plant employs a plantwide CO monitoring
system, with monitors in the coal-handling
motor control centers, multiple levels
within the tripper rooms, in each of the five
fuel silos located on each boiler, and so on.
CO monitors were recently installed in each
silo and have been connected into the HGS
control room information system. According
to a PRBCUG inspector, the " fire protection
systems in the coal handling areas are consistent
with industry best practices. "
During a plant inspection tour, system components
were identified and operating instructions
were readily available at the panels. One
unit (Unit 1) has a cascade system. Units 2
and 3 have trippers (shuttle car). In the tripper
room for Units 1 and 2, sidewall open nozzles
at two levels provide for coverage of the conveyor
and hazard areas. Linear and spot heat
1. Preventing coal dust. The bottom dump trestle unloading system uses water to suppress
dust. The train speed is restricted to 1 mph to reduce fugitive coal dust emissions, so it
takes about one and one half hours to process a train. Courtesy: Harrington Generating Station,
Xcel Energy

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POWER July 2015

Table of Contents for the Digital Edition of POWER July 2015