PlantWeb architecture at Akzo Nobel's Mannheim plant
Multinational Akzo Nobel has long been called "the world's
largest little-known chemical company," and even today,
only industry insiders know that Herbol®, Glasurit®,
and Sadolin® are trademarks of Akzo Nobel, as are the
corporate designations Organon, Lesonal, or Sikkens. Its Mannheim
plant is a member of Eka Chemicals' Paper-Chemicals Division.
Paper chemicals are employed in the manufacture and treatment
of a wide variety of papers and paper products, from letterhead
through cardboard, packing cartons, offset-printing paper,
photocopier paper, and carbon paper to unsized tissue paper.
Akzo Nobel's Mannheim plant manufactures sizings, i.e., chemicals
that convert relatively loose-weave cellulose matrices, the
familiar blotting paper, into paper that may be written on
or used for printing.
The Process
 PlantWeb
architecture with the DeltaV automation system has been incorporated
into one of the plant's production lines that is being used
for manufacturing a resin-based sizing employing a new process
in which two components, the resin involved and an emulsifier,
are combined in a single-stage, high-pressure process. Both
components are metered online, predispersed, and the resultant
mixture homogenized. The entire process takes from one to
three hours, depending upon the quantity being manufactured.
The final product is a viscous, milky suspension of particles
whose diameters should be less than 2 µm in order for
them to remain in suspension. Manufacture of this suspension
is a continuous batch process. The raw materials involved
are prepared in batches and fed to one of the plant's existing
production systems, which is equipped with conventional process-control
instrumentation and control systems.
Decision-making criteria: Favorable experience with the
system and an innovative approach
Dieter von der Ruhr, manager of the Mannheim plant, had this
to say regarding the decision to adopt the DeltaV system and
PlantWeb architecture: "Akzo Nobel, and particularly
Eka Chemicals, are currently of the opinion that any new system
built should be equipped with a process-control system, since
system controllers and system reliability should conform to
a certain state of the art and allow meeting the more stringent
quality standards demanded of certified systems, as dictated
by Eka's Swedish parent firm." As he went on to say,
"The first step is taking a look around and finding out
which systems have yielded favorable experience, and we found
that Emerson Process Management's DeltaV system was already being used
at several plants in, e.g., China and Sweden. In-house, we
rapidly came to the conclusion that the DeltaV system was
the system of choice, since its performance/price ratio seemed
to be better than those of competing systems from other suppliers,
where the fact that it was already being used with favorable
experience, could be used to control several systems without
making any changes, and employed an innovative approach were
the major criteria." Controllers have been used on older
sections of the system involved for several years. One controlled
the operations of an extensive tank farm. Another controlled
the manufacture of the wax-based suspension. These two controllers
did not communicate with one another or with the plant's network.
However, the DeltaV system is incorporated into our plant's
internal network and is thus also able to communicate with
the outside world.
 Dieter
von der Ruhr emphasized that "The system had to be innovative,
provide facilities for interfacing it to our existing in-house
plant-network systems, include data-logging facilities so
that we could analyze data offline, and employ a data standard
that could be accommodated everywhere. It needed to have facilities
for interfacing it to the various manufacturing operations
and laboratories at our plant, which are internetworked via
Windows NT. We operate a leased line to our German headquarters
at Düren, which also allows us to transmit and receive
company-internal business data via SAP. Those communications
facilities were, so to speak, a special decision-making criterion."
He described his role in choosing the system as follows: "We
played a relatively minor role in the selection process. Since
there were no process-control systems here at the plant at
that time, i.e., there were no grounds for choosing any particular
system, it was, of course, difficult for me, as plant manager,
to say '... I prefer Manufacturer X or Manufacturer Y.' Choosing
a system is an area where one has to follow the standard prescribed
by the parent company. The basis for the process involved,
along with what was available in the way of useful prescription,
had all been developed in Sweden, where Emerson was
heavily favored."
Lower manufacturing costs, thanks to single-stage operation
Starting out with the conventional two-stage process for
manufacturing the resin-based sizing involved, Akzo Nobel
investigated the matter of whether a direct, single-stage,
process would be cheaper than the process currently employed,
which was very expensive, since the materials employed had
to be handled twice. Of course, the new process could also
be manually run, since automation was not essential. As Dieter
von der Ruhr put it, "However, the idea of automating
the process arose from the consideration that it would allow
running several processing systems from the existing control
room, with probably just a single person working in the control
room and one or two people working in the field. That was
the reason for automating the process. Once the process has
been started up, it will usually continue to run without further
human intervention."
A Foundation Fieldbus for interfacing field instrumentation
Foundation fieldbus has been employed for interfacing field
instrumentation. The criteria involved in making that choice
were varied. One was that Akzo Nobel regarded Foundation fieldbus
as an innovative advance that will be around for a while.
As Dieter von der Ruhr put it, "That technology will
become the state of the art in certain types of manufacturing
operations." Yet another argument that surely favored
fieldbus technology was that it is much simpler and much easier
to install and takes up much less space. The system was installed
in an existing building with a control room that was nearly
filled to capacity with equipment, so space was at a premium.
Now that the system has been installed, there is no room left
for future expansions.
To Eka Chemicals, this represents a test, since this is the
first time that a fieldbus has been employed on comparable
systems anywhere within the company to date. Although the
same types of systems have been operated using Emerson
instrumentation and DeltaV systems, those systems employed
instrumentation controlled by 4 mA - 20 mA current loops.
Most of the systems at its Mannheim plant have been designed
for fieldbus control. However, some of the systems involved
in this project, namely remote sections of the plant's infrastructure,
such as its tank farm, are still controlled by 4 mA - 20 mA
current loops. The decision to test fieldbus technology at
the Mannheim plant was also based on the fact that the process
involved is inherently safe. Although it involves high temperatures
and high pressures, the hazards involved are understood and
can be reliably controlled.
Nevertheless, Dieter von der Ruhr believes that there still
are some psychological barriers to employing fieldbus technology
throughout the industry: "In the case of systems that
demand high safety standards, we here in Germany still have
some reservations about fieldbus technology, since we prefer
to rely upon proven standard technologies that may be configured
to provide full redundancy if circumstances warrant, and we
still have a few problems in adapting fieldbus technology
to suit our applications."
 All
items of field instrumentation interfaced to the fieldbus
were supplied by Emerson. Employing exclusively Emerson
instrumentation was regarded as a sensible approach for several
reasons. One was that Akzo Nobel did not want to risk other
manufacturers' instrumentation being incompatible with the
system or the bus. Another was that the plant's operator would
have a single supplier as its contact point for everything,
from the control system, right down to the last item of instrumentation
in the communications chain. It could call upon Emerson
whenever there were any problems with any item of instrumentation,
the control system, or the bus. Dieter von der Ruhr added
that, "This was a joint project. I must say that Emerson's
internal communications proceeded smoothly throughout all
phases of the project. Even urgent requests for information
from parent firm in the USA were promptly answered."
Dieter von der Ruhr summarized his experience to date with
PlantWeb architecture and the DeltaV system as follows: "The
system has been running for just under a year now and if I
had to do it all over again, I wouldn't change a thing. I
doubt that we made any major errors in our development effort.
We also trained our operating and system-maintenance personnel
on the system, and I regard it as particularly important that
someone should be on hand to handle system maintenance at
all times. Our collaborations with Emerson's personnel
proceeded smoothly. All of our questions were answered in
short order. I also found their post-installation support
to be good, almost too good. The extremely useful aspect of
fieldbus technology is that Emerson can take a look
inside individual items of instrumentation from outside our
plant, e.g., from its headquarters operation at Haan, using
PC Anywhere. That helped us a great deal during system startup
and while instrumentation was being installed."
back to top
|
