Waste-To-Energy Power Plant Migrates Control System for
Integrated Regulatory, Business Management
By Ron Richter
As North America's population and affluence increase, so
do its energy needs, and the amount of waste it produces.
When you're in the business of turning waste into energy,
you learn a lot about what's in our garbage. For instance,
seasonal high mercury levels in Vancouver area waste doesn't
come from area industries. Rather, it's absorbed by the local
vegetation from the earth -- a natural by-product of volcanic
eruptions that formed the land mass. On the other hand, the
increasing quantities of lead in the plant's waste come from
an ever-growing quantity of aged, discarded computer monitors
and CPU's.
 Garbage
is big business, and waste incineration plants like the Greater
Vancouver Regional District's (GVRD) Burnaby facility are
among the most closely monitored and regulated businesses
on the continent.
The plant, with 1100 control I/O, is operated by Montenay
Inc. Montenay, a subsidiary of French company Vivendi, operates
eight such facilities in North America, and employs some 240,000
worldwide. This plant, with 40 employees, processes approximately
250,000 metric tons per year of municipal solid waste on a
mass-burned basis. The plant produces steam, which it sells
to the adjacent recycle paper mill, Crown Packaging, Limited.
Crown uses about 50% of the incinerator's available steam.
Montenay condenses the rest while seeking markets for the
remaining 50%.
The Burnaby plant operates along classic boiler operation
patterns. Each of three boilers, operating at over 1000 degrees
Celsius, burns about ten tons of residential and light commercial
waste per hour, or about 700 tons a day .
The heat generated from the burning waste, and the flue gas
is drawn through a combustion chamber with an induced draft
fan on its back side. The gasses pass out of the steam generator
into the super heater section, and then into an economizer,
which uses the heated gas to preheat water that will go into
the steam drum. From there the products of combustion are
sent into a conditioning tower that cools them using water
injection. A second tower introduces a very fine hydrated
lime and activated carbon. The lime and activated carbon scrub
flue gasses of the various pollutants generated during the
garbage combustion. The reacted lime and carbon, together
with fly ash, is collected in a fabric filter and conveyed
to a fly ash silo. The combination of these three units comprises
about 40% of the plant's construction cost, and they represent
the plant's major consumables cost. We continuously monitor
the stack gas for oxygen level, carbon monoxide, nitrogen
oxides, sulfur dioxide, total hydrocarbons and opacity. Then
we report the results of these tests to government environmental
control agencies.
The move to migrate
In 1998, we were prompted to convert the plant's existing
control system when we learned that the system had Y2K compliance
issues. In a business that is so closely monitored for environmental
compliance, any inaccuracies in time and date stamping of
historical emissions reports could create huge headaches.
This prompted an investigation into new technologies. We weighed
minimal upgrades against a more comprehensive changeout of
the 1985-era technology. Maintaining, replacing and repairing,
inventorying supporting and upgrading the dated system could
become increasingly costly. In addition to cost considerations,
we looked for a state-of-the-art system with all of today's
technological advances, as well as a proven track record,
expandability, and an open path to future control developments.
We selected Emerson Process Management's digital,
PC-based DeltaV digital automation system, with local sales, engineering and
support from NORPAC Controls Ltd. Montenay and GVRD shared
the capital investment. Our plant operators and management
team felt that the system best represented the way Montenay
wanted to computerize control of the facility with emphasis
on the intelligence and software sides of the process control,
rather than focusing on dedicated hardware. Montenay Burnaby
envisioned the system moving toward the convergence of elements
like the DCS, and Montenay's own office network operating
system -- opening number of local and wide are network integration
possibilities.
Installation challenges
A key concern in making the changeout was whether the manufacturer
and local control firm could change out an entire distributed
control system and keep the control rock-solid reliable. The
most critical issue was downtime. As a major component in
the solid waste management system for the lower mainland of
British Columbia, we couldn't afford to be down for a week
or two. So timely delivery, scheduling, changeout, commissioning
and startup were crucial.
Reduced wiring cost
To minimize downtime during the changeout, and to reduce re-wiring
expense while installing the new control system, NORPAC left
all the original system's termination panels in place. The
engineering team picked the field signals directly from the
existing systems field wiring termination panels. The signals
were taken to the new system as a raw signal by utilizing
the configurable nature of the existing DCS manufacturer's
field termination boards. A series of DIP Shunts were reprogrammed
to provide a pass-through function on the termination board.
This removed all components such as resistors, filters, and
fuses from service on the old termination boards.
 Reduced
downtime
NORPAC engineers created a multi-pair cable with a new connector
to mate with the old system's termination panel. This new
cable was pre-wired into the DeltaV system. This reduced the
number of terminations at change over time from thirty-two
to one. With this methodology, NORPAC and Montenay was able
to change over the field wiring for each boiler in about 5
hours. NORPAC's Steve Priest notes, "If we'd had to re-wire
each of 1100 I/O, points in the field, it could have easily
taken twenty times that long. Essentially, we took a process
involving 4 wire terminations per point, equaling about 352
man-hours or 30 days' rewiring-and reduced it to 48 hours,
an 86% reduction in both time and installation expense."
Every pair of wires was loop-checked after the conversion
before placing the unit back in service. This migration method
not only reduced wiring time, it also reduced the chances
for wiring errors and associated trouble-shooting time. Working
the downtime scheduling into routine annual boiler maintenance
and shutting down one boiler at a time, the plant's total
combined downtime for the three boilers was 216 hours. Each
hour represented tenths of a percent of budget, because waste
during shutdown had to go somewhere else for disposal like
to a landfill, which GVRD had to pay for. The plant also was
not getting steam to the paper mill, and so was losing that
income.
Improved, integrated documentation
A lot of time at the Burnaby plant is spent in documentation.
The Continuous Emissions Monitoring System (CEMS) in particular,
is our biggest integration. Under the old system, we received
paper copy from CEMS's environmental Data Acquisition system.
Operations wrestled with that information for many man-hours
each month for environmental reporting. With the new system,
that environmental report is available to us in Excel spreadsheets.
The data for the Excel spreadsheet is populated through the
system's integration onto the plant's local area network.
 GVRD
is responsible to compile and send monthly operating reports
on the facility to the Provincial Ministry of Environment.
GVRD staff can now dial up and view current plant operating
data, including boiler overview graphics, on their desktop
computers. They also have access to the same Excel spreadsheets
and status reports we produce at Montenay operations.
The big advantage we've gained from the DeltaV system has
been the ability to cut and paste back and forth out of Excel
for use in our reports. Right now, we e-mail those reports
to our head office in New York. We're confident that the DeltaV
can produce that information in New York over our Intranet
in real time, which will produce further administrative time
and labor savings.
Improved Information Flow
Several months ago, our Excel reports pointed to a four-hour
incident in which an operating parameter was out of control
range. A quick look through the trends for the time in question
showed the inconsistencies, which turned out to be a measurement
failure, rather than a control problem. We did all that analysis
in five minutes, pinpointing a point in time two or three
months prior. This analysis could have easily taken a couple
of days under the old paper copies and multiple recording
systems.
Looking to the future
We intend to continue integrating plant information into the
office LAN. We are confident that we will see savings in utilizing
the plant from the improved view of the operating conditions.
 The
small footprint of the DeltaV control system saves us a lot
in installation costs alone. It's going to make viable some
projects that were marginal before. Other possibilities for
future expansion include advanced control. We had been using
a stand-alone system running a Neural network technology to
optimize flue gas scrubbing. We plan to pull that into the
DeltaV with its advanced control packages for environmental
control of pollutants. If we can better control the amount
of lime that we put into the system, it will reduce many tasks
that we do, and it will reduce our consumables costs. As we
upgrade the emissions monitoring equipment here, DeltaV will
be a fundamental part of the implementation.
I think the biggest benefit the Montenay Burnaby plant made
with this migration is the implementation of a system that
can take us into the next ten or twenty years, with the ability
to expand with the facility. We're confident that this system
will be a major advantage in any future developments. Further,
Montenay believes the system's maintenance cost will be greatly
reduced as a result of the off-the-shelf equipment built into
the DeltaV system. And with the system's built in asset management,
we expect to see a substantial pay-back in reduced long-term
plant maintenance cost. Combine that with local support from
the manufacturer's representative office, and it's a perfect
combination.
Ron Richter of Montenay, Inc. is Plant Manager of Greater
Vancouver Regional District's Burnaby waste incineration plant
in Burnaby, British Columbia, Canada.
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