Automation systems are developing so fast that process engineers can only marvel at what is on offer as mills reap the financial benefits

Mill-wide automation makes for smooth changes

Taken together, these two strands of software and hardware development - increasingly powerful computer systems and far more open architectures - have allowed the paper industry to embrace mill-wide automation on a scale that would have been unimaginable 20 years ago.

Added to that, the current trend in the pulp and paper industry toward consolidation is compounding the need for more advanced processing strategies, not just for production planning, but in terms of a company's sales and marketing functions as well.

The developments taking place are fundamentally changing the way in which pulp and paper producers and customers do business with each other. Producers are trying to meet ever more demanding customer specifications while attempting to slash production costs. At the same time, this process has spawned a rash of technological developments in automation and control as suppliers race to realize the possibilities created by rapidly advancing computing power.

ABB is clear on where it believes the future lies. With the industry undergoing extensive consolidation, the supplier fully expects the paper market to be dominated by a few truly multinational companies in the future. In order to differentiate themselves, ABB believes that the leading companies will have to become even more customer oriented. This will have significant consequences for mill production management as well as the IT systems that control them.

"One of the challenges in the new situation is the more dynamic scheduling of the mill production," according to the company. "In the past, rough production schedules were typically fixed for a production line, basically forming a sequence of grades that repeated after a number of weeks. The orders were then confirmed against this schedule. In the new situation, the mills are required to be more flexible in the name of better customer service. But without new tools for production scheduling, this is rarely possible due to high grade change costs at the PM. On the other hand, once the order is confirmed into production, the mill level systems have to be able to answer flexibly to the dynamic changes present in the manufacturing environment. They also have to optimize the mill production process to facilitate lowest possible production costs for any given order."

ABB's answer to this particular shift is a new production scheduling algorithm, which has been integrated with ABB's Production Planning Software (PPS). The new optimization method is capable of minimizing grade change costs at the paper machine, without sacrificing other planning objectives, such as on-time delivery and minimization of warehousing costs. According to the supplier, the new algorithm allows paper mills to optimize production schedules to maximize total mill productivity.

Increased emphasis on the customer's needs has also increased the importance of end-product quality control. As ABB points out, mill IT systems now have to be able to support screening of the off-spec product before it reaches the customer. This can be achieved through proactive quality control. For example, the mill can now utilize on-line quality information from the QCS (quality control systems) and combine it with information from the product tracking system. In this way, a mill could calculate the quality parameters of a given customer reel and compare them with the customer's specific quality requirements before the reel is even cut at the winder.

Open days

Reflecting the trend toward greater openness, the latest version of the TotalPlant Alcont process automation system from Honeywell-Measurex features OPC data access service, Intranet online documentation and an integrated fieldbus process interface. In other words, the system is designed to provide increased flexibility and openness.

The Honeywell-Measurex system makes use of the OPC interface standard, or OLE for Process Control. This enables online data access between systems and applications over the mill control and information networks.

According to Honeywell-Measurex, it is one of the first to have included an OPC server in its process automation system. This allows existing and emerging OPC-compliant Windows applications to access real-time process values transparently through the system on a globally standardized interface. Current applications using mill-wide OPC access to process data include process history collection and retrieval, product quality control, process supervisory control and process simulation.

Intranet online documentation in the TotalPlant Alcont system also provides operator access to process and loop descriptions stored and managed in a web server along the mill intranet. The descriptions - ordinary text documents with pictures - are assigned to process areas covered by individual schematic displays and to individual control loops. They are available to the operators as online help through a right mouse click on the corresponding schematic or loop faceplate on the control room displays.

The integrated fieldbus process interface of TotalPlant Alcont uses de facto standard fieldbuses as media to access process I/O. This means the user has the ability to connect I/O units and intelligent field devices from independent manufacturers to the system. The units can also be installed in locations distributed around the mill. Interbus is currently the best supported open standard fieldbus in the Alcont system. Its data transfer performance is compatible with the machine control speed requirements in paper machines and printing presses.

The profound integration of the fieldbus interface and related engineering tools to the automation system provides remarkable benefits, especially in mill-wide automation systems. All fieldbus-based process interfaces, regardless of their physical locations in the mill or points of connection to the system, can be configured, managed and maintained at one engineering workstation.

Aspen Tech points out that there are other major drivers in the paper sector that are generating new developments and approaches to mill-wide control strategies. Energy and the environment are two of the most important, according to the supplier. "Energy efficiency, CO2 reduction etc, as defined at the Kyoto conference of 1997 will become the key. All kinds of industry, and certainly the pulp and paper industry, will have to prove that they are making major efforts in energy reduction and energy optimization," Aspen Tech said.

To meet this challenge, the company has been working closely with several paper mills and Siemens' Advanced Process Control group. The companies have started R&D programs based on the Millwide Information and Management System for the Pulp and Paper Industry, MIMS (PPI March 1998, p39).

Aspen Tech maintains that energy management has to be done in conjunction with sound product management as quality and specific costs are linked with each other. Instituting a top-down approach to monitoring the performance of the paper machine in real-time at production level is the first step, according to the supplier. The second is reporting and advisory control using case-based reasoning techniques. This means that the target for the running production will be the best practice attained in earlier production situations. The last step is a global supervisory control where key indicators such as energy efficiency indices (EEI), cost efficiency indices (CEI) and product efficiency indices (PEI) are the only setpoints that control the global mill.

Quick view

Clearly, the sheer number of new developments in this sector could not possibly all be covered in the limited space available here. A whole host of companies are actively involved in developing systems for the paper industry. But what is clear even from this snapshot is that there is still some way to go before all the collectable data available in pulp and paper mills is seamlessly integrated into the sales and production process.

But at the rate new systems are being introduced, it surely cannot be long before seamless integration on such a scale becomes a reality.

The new algorithm on ABB's production planning software helps optimize the process

Stora Enso Berghuizer chooses quality

After an extensive evaluation of the solutions available, Stora Enso's Berghuizer mill selected ABB's Quality Management System (QMS) for its mill upgrade in Wapenfeld, the Netherlands. The new setup will replace the plant's existing system to provide proven functionality, flexibility and Y2K compliance.

In addition to comprehensive functionality, ABB's flexible product approach was key to Berghuizer's decision. According to the quality assurance director at the mill, Jan te Hennepe, "Flexibility is an absolute necessity in papermaking, with its constantly changing interests and demands. ABB and its QMS product provide flexibility, allowing us to grow further in quality management and respond effectively to the constant change."

ABB's product approach, in which a defined "roadmap" guides development of new versions of a standard product, was also important. "Knowledge and ideas of customers are reviewed and fit into the QMS roadmap," explains Wim Berends, so Berghuizer's quality coordinator.

QMS will manage quality data from throughout the Berghuizer mill, which runs three paper machines and eight sheet cutters. Data from the mill's AccuRay gauging systems will be provided to the QMS by ABB's configurable Information Exchange Software (IXS). Laboratory data will be provided using AcquiData's Testream/CS, while order, run and production data will be integrated through an interface to the mill's in-house product tracking system.

QMS and IXS are hosted on HP-UX servers running Oracle and employees can access the new system via Windows-based PC workstations.

New openness at UPM-Kymmene's Kaukas mill

UPM-Kymmene's Kaukas mill in Lappeenranta, Finland, wanted Honeywell-Measurex to deliver uniform paper production line automation for its most recent automation investment. All process controls, from quality systems to basic control loops, including the machine controls and the handling of hydraulic and pneumatic actuators, had to be implemented in a uniform system environment using common design tools and approach methods.

The first stage of the project was launched at the beginning of 1998 and was concentrated on coating machine #2. The new PM 2 system started up in the middle of 1998 and toward the end of the year, the control room of coating machine #3 was upgraded using the new NT-based Alcont technology.

All process control functions for the machines have been implemented using the Alcont system. In addition, Alcont caters for both the coating machine's fast machine controls and those of PM 2, which are conventionally implemented with separate PLCs. Alcont's fastest control cycle is 20 ms and covers not only logic functions, but also all control methods. Thus, it enables the use of various calculation and control algorithm types. Examples of these are the protection algorithms of PM 2's zone roll controls and the online load pressure calculations for machine reels.

Parts of the PM 2 process connect to the Alcont system via the Interbus fieldbus. The fieldbus is an integral part of the automation system and the operator sees the Interbus connected process interfaces in exactly the same fashion as the other interfaces. The zone roll optimization algorithm was supplied by a third party and is executed in the NT environment that connects to the Alcont system via an OPC interface.

The project manager at the Kaukas mill for the AUTO-2000 program, Risto Tavia, says that even during the project planning stage, the objective was to exploit the new capabilities provided by open systems for information collection, data presentations and process interfacing. This user environment also enables systematic troubleshooting and accurate tracing of causes in disturbance situations. Not only that, but just three days after the last stage had been started up, PM 2 hit a new speed record.

Aspen Tech's system monitors key performance indicators against targets and low limits

Blending fingerprints into quality pulp

Being at the top is nothing new for the pulp mill at Kemi in Finland - you can't get much farther north. But being top has long been the aim of Stora Enso's Veitsiluoto pulp mill - from pulp quality to investing in pioneering equipment.

The pulp mill's elementary chlorine-free (ECF) bleached softwood and hardwood pulp is used to feed the Veitsiluoto paper machines. Since it started up in 1977, the pulp mill had been operating with Valmet Automation's Elmatic 100 equipment, based on analog measurements. The Measurex optimization controls in use dated back to the same time. Valmet's Damatic Classic control system was installed in 1988 for the effluent water department. But as making changes and getting spare parts became increasingly difficult, it started to become impossible to expand the control system to meet the growing capacity needs. The mill decided that a complete automation renewal was required.

In 1995, Valmet supplied automation systems for a major rebuild that took in the evaporation plant, new super concentrators, screening, the causticizing plant, lime kiln and the recovery boiler's flue gases, electrofilters and flue gas scrubber. In 1996, the remaining parts of the recovery boiler were renewed along with the cooking and washing departments. Damatic XDi was also applied to the power plant.

"We decided to renew all automation on a three-year plan, including the information system, to enable the complete project to be managed in the most effective manner," explains project manager, Pentti Tolonen. "As our annual shutdowns are only one week long, it would have been too great a risk to complete the entire project at once."

Fuzzy logic and optimizing controls have been applied as an integrated system to the recovery boiler, digester and bleaching processes to optimize operations. A separate project to supply optimization controls for the lime kiln was completed last month.

Pentti Tolonen (left) and Esa Frant (right) discuss the fuzzy logic optimization system for blending fingerprints from different operators over five different shifts

Cutting back

To optimize bleaching chemical costs, Veitsiluoto chose to take the pioneering application of Valmet Automation's new D-stage control solution. This application made Veitsiluoto the world's first to use absolute target values for brightness. The control solution is based on Valmet's Kajaani measurements - KappaBright, Cormeci and Polarox - and Damatic XDi controls.

The XIS information system is one of the most sophisticated parts in the Valmet Automation delivery. It covers the whole recovery line, fiber line and laboratory values. Operating models can be included in the XIS historical database to aid the operator. According to the production director, Veli Väyrynen, the integrated information and automation system has made a significant impact. "The latest information on production and process status is available to all who need it. When the data is saved in the memory, it facilitates the determination of various disturbance situations," he says.

From Valmet Automation's point of view, this delivery was the most comprehensive, including much of the company's latest measurement equipment, optimization controls, information systems and mill-wide control systems.

"It is fair to say that the automation work has paid back within a few years. No production losses at all were caused during the startup of the automation", says Tolomen.

Compared to baseline figures in 1994, advanced, continuous cooking controls at the mill have produced favorable results. "With our new D-stage control system, we have achieved final brightness with optimum chemical consumption," Tolonen says. "Results indicate satisfactory decreases in deviations in brightness and Kappa. Hardwood deviations have reduced to 0.45, a decrease of 50%, and softwood pulp brightness deviations gone to 0.4, a decrease of 40%. Final pulp requirements have been exceeded with figures of 90 ISO brightness."

Väyrynen adds that the renewed automation system has definitely had an impact on achieving both the pulp brightness targets as well as savings in steam and bleaching chemicals. "Total chlorine dioxide consumption has been reduced by 1.9 kg/ton for softwood and 1.5 kg/ton for hardwood. This represents a saving of nearly 600,000 kg/yr of chemicals," Tolonen confirms.

Additional text by Lisa Kettman-Kervinen, Valmet