POWER
Ovation® Migration Saved Xcel Energy’s Pawnee
Plant $2.4 Million and Reduced Startup by 4 Days
RESULTS
● Saved an estimated $2.1 million in hardware by reusing
existing I/O cards and cabinets
● Saved an estimated $325,000 in labor costs
● Decreased off-hours overtime in I&C and electrical
departments by 5%
● Reduced plant startup time by 4 days
APPLICATION
Coal-fired unit consisting of a Foster Wheeler natural circulation reheat
boiler with front and rear firing and a GE tandem compound four flow
reheat turbine
CUSTOMER
Xcel Energy, Pawnee Power Plant, located in Brush, Colorado
CHALLENGE
Xcel Energy’s Pawnee Station began commercial operation in
December 1981 using a combination of Westinghouse 7300
combustion controls, a Control Data Corporation data acquisition
system, a Westinghouse boiler interlock and interposing relay system,
and a Forney burner management system. During the period of
1991 through 1994, Xcel replaced these controls, including much
of the balance of plant, with an Emerson WDPF system. Changes to
environmental regulations and plant operating conditions required yet
another upgrade to further improve plant performance. Goals for the
project consisted of:
● Implementing new technologies including asset management,
advanced control algorithms for enhanced sootblowing, and
discrete busses for smart instrumentation
● Executing a migration program that would meet technology goals
and provide a path for future growth in an economical manner
● Employing a user-friendly system with an accessible support
program to assist the Pawnee staff with re-engineering activities
For more information:
www.EmersonProcess-PowerWater.com
®
© 2006 Emerson Process Management Power & Water Solutions, Inc. All rights reserved.
“In 1987, Pawnee Station
management made a
commitment to have a consistent
approach to plant-wide control
that would be expandable,
keep up with technology, and
allow leverage of installed I/O
as other hardware and software
is upgraded. Emerson products
have continually met that
commitment.”
David Low
Station Director
Xcel Energy
Pawnee Power Plant
POWER
SOLUTION
Xcel implemented a program that migrated their existing WDPF
equipment to Emerson’s Ovation® expert control system. The new
Ovation system is fully expandable, offers a larger point capacity to
handle future growth, and has the capability to implement discrete bus
technology.
Migrating from WDPF to Ovation provided Pawnee with increased
control system capacity for system expansion. With Ovation, Xcel
can easily incorporate new plant areas and future additions of plant
equipment or process locations. The Pawnee control system migration
was performed within budget and time constraints. Xcel saved an
estimated $325,000 in labor costs typically associated with field wiring
and checkout time. An additional $2.1 million was saved in hardware
costs due to the extensive reuse of existing cabinets, I/O, and cabling.
Improved control strategy was achieved through re-engineering
performed by the Pawnee staff. Advanced sootblowing algorithms
were installed to more efficiently administer sootblowing sequences
for maximized boiler and heat transfer efficiencies. Additionally,
automatic sequencing with diagnostics was programmed for
optimizing equipment startups. This portion of the re-engineering,
along with training of all plant personnel on the use of the Ovation
system, dramatically reduced troubleshooting time by electrical and
maintenance personnel.
“Installation of the WDPF system
made controls programming,
use, and troubleshooting 10 times
better than the older systems.
Migrating to Ovation has doubled
that improvement. Additionally,
Emerson’s service and support
has always been excellent,
thus making our job of system
operation, maintenance, and
enhancements easier.”
Gary Alexander
Engineering Analyst
Xcel Energy
Pawnee Power Plant
The Pawnee technology migration incorporated Emerson’s PlantWeb®
digital architecture by combining Ovation, AMS® Suite Intelligent
Device Manager, and Foundation™ fieldbus instrumentation for
plant data acquisition. Emerson’s Rosemount® 848T temperature
transmitters are connected to the Ovation system through two
Foundation fieldbus segments. Additionally, the plant uses
approximately 110 HART-enabled Rosemount Analytical instruments
and Fisher® DVC HART positioners.
Pre-outage simulation and testing on the control schemes and logic,
along with the system’s ease of use, allowed the unit to be started up
without any delays due to the control replacement project, resulting in
a four-day reduction in plant startup time. An Emerson SureServiceSM
Maintenance contract with remote diagnostic capability provides
instant troubleshooting to both Ovation and plant problems, thus
further reducing maintenance time and costs.
For more information:
www.EmersonProcess-PowerWater.com
®
© 2006 Emerson Process Management Power & Water Solutions, Inc. All rights reserved.
The Pawnee plant staff designed an Ovation system
sootblowing control diagram for more efficient
administration of sootblowing sequences.