PlantWeb Automation Keeps Generating Plant Steaming
 The
first field-based process control system to run a utility
generating plant has successfully gone on line at the 52.1
MW, lignite/gas-fired Lewis & Clark Station, Montana-Dakota
Utilities Company.
The relatively low cost automation, which replaced 1958 pneumatic
controls, delivers smoother control and is making for fewer
trips, safer boiler operation, and higher efficiencies. The
automation has also reduced operating manpower and is extending
station life. Previously, the plant couldn't qualify for spinning
reserve duty because too much time was required to increase
load. Today, load can be raised 5 MW in less than 10 minutes.
The proven PlantWeb digital plant architecture
from Emerson Process Management relies on compact and modular DeltaV
controllers mounted near the equipment controlled in un-airconditioned
cabinets, minimizing field wiring. Versatile FOUNDATION fieldbus
control communications, PC workstations, an Ethernet supervisory
network, and Windows-based configuration software programmable
by MDU engineers round out the technology. Montana Dakota
Utilities investigated installing a conventional DCS to automate
the station, but determined that the projected high cost might
not be recoverable.
All station equipment except the turbine and coal handling
was automated. Included were the boiler, burner management,
natural gas delivery, fuel/air ratio, mills, burner tilt,
sootblowers, condensate and feedwater systems, fans and dampers,
air heater, precipitator, scrubber, ash handling, intake house
screen and pumps, water treatment plant, and fire system start.
The redundant, FM-approved burner management system is the
first anywhere to reside in DeltaV controllers.
PlantWeb's fieldbus communications makes for the lowest controls
cost and the greatest versatility -- no I/O modules, ability
to distribute intelligence, exhaustive data collection, and
remote diagnostics, calibration, and maintenance capabilities.
Hundreds of variables are now gathered and trended every half-second.
MDU estimates fieldbus saved $100,000 in wiring costs alone.
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