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, a small facility with just a few employees, is a member of Eka Chemicals' Paper-Chemicals Division. Fisher-Rosemount's DeltaV system, which is based on Foundation Fieldbus technology, has been incorporated into one of the plant's production lines that is being used for turning out one type of paper sizing that the plant manufactures employing a new process.
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, ie 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
The Fisher-Rosemount DeltaV 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, pre-dispersed, and the resultant mixture homogenised. 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 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
Favourable 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. The first step is taking a look around and finding out which systems have yielded favourable experience, and we found that Fisher-Rosemount's DeltaV system was already being used at several plants in, eg 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 favourable 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 Delta V system is incorporated into the plant's internal network and is thus able to communicate with the outside world.
Von der Ruhr emphasised 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 analyse 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 inter-networked via Windows NT. We operate a leased line to our German headquarters at Düren, which also allows us to transmit and receive internal company 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, ie 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 Fisher-Rosemount was heavily favoured."
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 Von der Ruhr put it, "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 the Foundation Fieldbus as an innovative advance that will be around for a while. As 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 favoured fieldbus technology was that it is much simpler and 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 Fisher-Rosemount instrumentation and DeltaV systems, those systems employed instrumentation controlled by 4-20 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 4-20 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, 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 Fisher-Rosemount. Exclusively employing Fisher-Rosemount 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 a contact point for everything, from the control system, right down to the last item of instrumentation in the communications chain. Akzo Nobel could call upon Fisher-Rosemount whenever there were any problems with any item of instrumentation, the control system, or the bus. Von der Ruhr added that, "This was a joint project. I must say that Fisher-Rosemount'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."
At the time of writing, the manufacturing system was not yet required to run at full capacity. Von der Ruhr summarised his experience to that 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 would not 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 Fisher-Rosemount'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 Fisher-Rosemount can take a look inside individual items of instrumentation from outside our plant, eg from its headquarters operation at Haan, using PC Anywhere. That helped us a great deal during system start-up and while instrumentation was being installed."
Fisher-Rosemount is represented locally by Alpret Control Specialists.
Alpret Control Specialists
(011) 249 6700
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