PlantWeb puts the fizz in American Soda
 At
American Soda, L.L.P., Inc. of Parachute, Colo., business
is bubbling -- literally. That's partly because of innovations
developed in the company's commercial solution-mining research
operation. Starting in late 2000, American Soda will be using
these advances to mine nahcolite, a raw form of sodium bicarbonate.
The nahcolite is used to make both baking soda, a refined
form of sodium bicarbonate, and soda ash, or sodium carbonate.
American Soda's goal isn't to be just another supplier. The
company plans to be the world's lowest-cost provider of both
materials in selected markets. This will be accomplished thanks
to improvements in both techniques and technologies. Included
in the technology improvements are a scalable primary control
system and FOUNDATION fieldbus devices that work together
as part of a PlantWeb field-based architecture.
So far, results from American Soda's research mining facility
in the Piceance Creek Basin in western Colorado have been
encouraging.
"New automation technologies have proven very effective
and will allow American Soda to produce soda ash and sodium
bicarbonate with far fewer employees than other United States
producers," said Mike Huffman, American Soda senior systems
engineer.
The research facility mines nahcolite by injecting hot water
into a nahcolite-rich oil shale deposit at a depth of 1,600
to 2,200 feet. The saturated brine returns to the surface
for processing and analysis. Thanks to the temperatures and
pressures involved, the highly concentrated nahcolite brine
has tested almost entirely free of impurities and petroleum
products. That makes the American Soda approach more cost
competitive than alternative methods.
 The
company intends to use the same process to solution mine 1.6
million tons of nahcolite annually to produce one million
tons of soda ash and 150,000 tons of sodium bicarbonate. Scheduled
to begin operation in late 2000, there will be two plant sites
located 44 miles apart and connected by pipelines. One site
will solution mine the nahcolite, while the second will produce
the soda ash and sodium bicarbonate. Doing so requires tight
process control and monitoring, both for commercial and regulatory
reasons.
The process automation solution selected for the commercial
plant and presently running the research facility uses PlantWeb
field-based architecture from Emerson Process Management. The architecture
proved ideal because its power and capabilities exceed those
of traditional solutions based on a conventional distributed
control system (DCS). The compact and substantially more cost
effective PlantWeb package offers a high degree of distributed
intelligence and extensive data collection, as well as remote
diagnostics, calibration, and maintenance capabilities. The
flexibility of PlantWeb proved important during the research
phase of the project, such as when an entirely new process
was installed.
"Expanding and reconfiguring the control system for
the new process was accomplished in only a few weeks -- and
by American Soda personnel," recalled Huffman. "This
wouldn't have been possible with a conventional DCS. I did
much of the configuration myself even though I have limited
programming knowledge."
To gain experience with fieldbus, American Soda installed
a DeltaV automation system and nine FOUNDATION fieldbus registered
devices from Emerson to run one of the research facility's
100 percent capacity heat exchangers plus a condensate level.
The fieldbus instruments include temperature, pressure, and
level transmitters, digital valve controllers, and Coriolis
and magnetic flowmeters.
Since it was continuously operating, the heat exchanger provided
a real-world test. It also allowed Huffman and his co-workers
to test the technology by trying to induce failure by shorting
and severing communications. The attempt to create a failure,
however, was a failure. The fieldbus instruments continued
to operate as last instructed.
Now nearing completion, the commercial plant will include
two processing plants plus 26 wells spaced over a mile of
rocky territory. The well field will rely exclusively on wired
and fiber optic FOUNDATION fieldbus communications. Not only
will this reduce cable runs, but devices can be diagnosed,
maintained, calibrated, and tuned from a remote workstation.
That can be vital when operating in less than ideal conditions,
as Huffman pointed out.
"During the winter, the terrain here can be nearly impassable.
We would also like to operate both the mining operations and
the Upper Processing Plant with just two operators per shift.
Remote wellfield servicing will certainly help in achieving
that goal," he said.
So, thanks to its own ingenuity and that of its partners,
American Soda is about to start cooking.
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