Publication: Pulp & Paper Magazine
Issue: September 1, 1995
Author: Author

SPECIAL REPORT

Sponsored by ABB

PROCESS CONTROL IN THE PULP AND PAPER INDUSTRY

SECTION 1: World Trends and Driving Forces...................2

European Priorities

Situation in North America

Asian Outlook

MES/EI Driving Forces

SECTION 2: The Move Toward Integration......................00

Halfway There

The Time is Right

The Payback Factor

Changing Role of The Operator

 

SECTION 3: Advances in Sensor and Control Technologies......00

From Mill Lab to On-line

Wet End Information Systems

Flocculation Control

Automatic Grade Change

Pulp Mill/Chemical Recovery

 

SECTION 4: Mill Automation and Control Strategies...........00

Hansol, South Korea

Soporcel, Portugal

Weyerhaeuser/Plymouth, N.C. U.S.

Aylesford, UK

Union Camp/Franklin, Va., U.S.

Sachsen Papier, Germany

YFY Group, Taiwan

Willamette Industries/Bennettsville, S.C., U.S.

Rohit, India

Vallvik, Sweden

 

PROCESS CONTROL IN THE PULP AND PAPER INDUSTRY
The Information Renaissance

This report was prepared by PULP & PAPER AND PULP & PAPER INTERNATIONAL editors, based on information gathered in interviews with various industry sources and visits to mills.

The pulp and paper industry worldwide appears poised to enter Phase II of a process automation renaissance that began in the early 1980s. A trend now emerging in Europe and North America, as well as Asia and other parts of the world, is full integration and maximum utilization of information from both the process and business sides of the industry.

During the past year, some mills have made significant progress toward fully integrated information systems. These mills are using the latest information technologies to better meet customer needs and quality demands, control costs, optimize profitability, and provide a safer, more environmentally responsible workplace for a downsized but highly trained staff of employees.

Efforts at these mills are mainly focused on "operator empowerment"--putting as much information as possible into the hands of operators so that decisions can be made as early in the production process as possible. Perhaps several steps beyond traditional MIS (management information system) concepts and objectives, the move to integrate process or shop floor information with management information into real-time "production information" is being referred to by some as "enterprise integration" (EI) or "management execution systems" (MES).

A unified mill information network will undoubtedly be a continuing trend in the paper industry as it moves into the next century. The era of control fragmentation within individual mills is rapidly passing, especially for greenfield mills.

But achieving MES or EI is proving to be a slow and tedious task for some mills. It requires not only dedication and a continuing financial commitment from management at all levels, but a complete "cultural" overhaul at the mill operating level. In this regard, employee training has become an essential, vital key to success.

Although many, if not most, mills around the world are highly automated with various levels of DCS/QCS implementation, more process control developments and breakthroughs are needed to take the industry to the next level of information integration. New and cheaper sensors, for example, are needed to bring more critical process information "on-line."

Computerized maintenance is becoming a byword in the paper industry worldwide, but more progress is desperately needed to help mills not only cut downtime and general operating costs, but hopefully reduce the high percentages of maintenance employees typical in today's mills--sometimes as high as 40%. Environmental monitoring and control is a costly and time consuming effort that, undoubtedly, will only increase in the foreseeable future.

As mills move further into the information integration era, the role of operators at the mill level will change dramatically. Armed with vast amounts of interpretable information and in close communications with all segments of the manufacturing process, operators of the near future will likely become the paper industry's true "on-line business professionals," according to Nils Leffler, president of ABB Pulp and Paper in Zurich, Switzerland.

This report examines the driving forces behind process control developments in the paper industry, and explores where mills are along the road to full information integration and what will be needed to finally get there. It looks at new process control advances in the paper machine and pulp mill areas, as well as other process and support functions, and assesses what more has to be done for the industry to enter the twenty first century alive and well.

Finally, this report also presents a collection of mill process control profiles from around the world, comprising a global report card of the industry's status and outlook.

SECTION 1: WORLD TRENDS AND DRIVING FORCES

From about 1984 in North America, and a few years later in Europe, until the end of that decade, the world paper industry modernized and expanded at an unprecedented rate. With spending for process automation tracking capital spending at a typical 4%-5%, mills in almost every country invested heavily in the latest computer control technologies.

As a whole, today's pulp and paper mills are dramatically more efficient than they were a quarter century ago. Due to the recent control "revolution," modern mills are now producing a ton of higher quality product at a considerably lower cost than their counterparts of the 1970s. They are also more energy conscious and environmentally tuned, and are in closer touch with their customers' needs and schedules.

In North America, the current paper industry upturn promises to be more prolonged than first anticipated in 1993. In fact, if some estimates prove to be on target, pent-up capital spending by U.S. companies alone could increase from the current $12-$14 billion to near $20 billion before the turn of the century, paralleling the 1984-90 growth boom.

In Europe, South America, Australia, and especially Asia, capital spending is also expected to rise for paper mill expansion and modernization projects through the remainder of this decade. If so, the industry could experience another process control "window of opportunity," allowing mills to take a second major step forward in the race to full information integration.

Customer service, quality management, cost control, environmental considerations, and the need to increase production (as well as shorter production runs) will all continue to be driving forces behind spending for process control and information technology in the near future. But some priorities are shifting, depending on what part of the world a mill is located.

Charles Rowland, vice president of ABB's Industrial Division in Columbus, Ohio, reports that worldwide customer surveys conducted by his company during the past year and a half show that most mills will be spending about half of their capital budgets for production increases, about 30% for environmental, and the remaining 20% or so on other improvements, including process control. Spending for quality appears to be losing ground in favor of production gains, at least compared with a few years ago.

Environmental spending in North America will be especially high during the next few years, according to Rowland, but the situation is almost reverse in the Nordic countries. "Some mills are able to sell almost anything and everything they can make right now, particularly in Europe. So production is the key concern," Rowland emphasizes.

"This is not a bad situation for process control suppliers," he adds. "Most new measurement capabilities, cross-machine actuators, etc. that mills might install will all contribute to production increases."

EUROPEAN PRIORITIES. In Europe, smaller mills are reportedly putting a greater proportion of their investments into process and product control than the larger mills. The major investments are in product tracking systems that permit greater visibility of inventory levels to remote sales operations, direct customer orders from merchants, and automatic scheduling and handling (which extends to off-machine operations and functions such as deckling).

The driving force for these major investments, according to European observers, is the need to shorten communication chains between customers and the mill production staff. This increases the visibility of the overall plant to both in-house and external customers. The shortening of the communications chain improves the standard and speed of information transfer. The benefits are reduced inventory levels, improved utilization of installed capacity and a greater level of customer service.

In Europe, the small mills tend to have an ad hoc approach to automation and process control. There are frequently many islands of data and information and a lack of overall system compatibility. Larger mills are reported to be investing in monitoring systems for fiber and filler retention, such as the Eka Nobel Chemtronics unit and other systems. On-line consistency and color measurement are becoming the industry norm. Future needs are for on-line sensors for product strength, particularly stiffness and tensile.

SITUATION IN NORTH AMERICA. In North America, process control trends are generally similar to trends in Europe, especially with the smaller mills. Large system orders have slacked off, and few major projects are on the horizon at this time. As mentioned above there has been some automation spending in relation to environmentally-driven pulp mill and bleach plant upgrades and for control of mini-mills.

The mini-mill trend in the U.S. began in the late 1980s, sputtered during the 1990-93 downturn, and now seems to be picking up again with a flurry of deinked mini-market pulp mills under construction or coming off the drawing boards.

Lars Ingman, vice president, paper quality control, Valmet Automation in Atlanta, Ga., believes that U.S. companies will not be using leveraged cash flow to finance capital spending as much as they have in the past. "Some of the U.S. companies' cash flows will fuel capital spending in the next few years, but they won't be borrowing $2, $3, or $4 against every cash flow dollar invested, as they have done in prior years. The ratio at least will go down, to maybe a dollar or half dollar borrowed for each dollar invested."

Again, much of the U.S. investment will be earmarked for recycled and environmental projects, Ingman points out. "There isn't much business in the U.S. right now for big DCS or QCS systems--just a lot of small process control projects. The situation is better in Canada."

ASIAN OUTLOOK. In Asia Pacific, Scott Morris of Honeywell-Asia reports that new facilities are generally looking at world-class solutions. They are interested in the latest technology in control system hardware, sensors, advanced controls, and production management systems, he points out, adding, however, that "in many cases, process control is only looked at late in the project cycle, and is therefore not fully coordinated with the process and is often not implemented because of lack of funds."

As far as the next step for Asian paper producers, Morris says that "we are seeing more process automation interest in the smaller, existing pulp mills." He emphasizes that Asian clients are more concerned with quality now than in the past, and there is more concern and spending on environmental protection.

"While many mills can still sell all they can make, they are now interested in the newer sensor technologies and control strategies as ways to improve quality and efficiencies," Morris sums up.

Sources report that in Asia, generally, Japan and Korea are more advanced process control-wise than other countries. An interesting twist of strategies are those in the most populated countries of Asia, China and India. While Chinese companies are said to be installing only basic process control technologies on newer paper machines, India is tending to install used machines with very advanced automation systems.

MES/EI DRIVING FORCES. Factors driving the worldwide move to MES or EI will be numerous, according to Leffler of ABB. Many DCS/QCS systems are 10-15 years old and must be replaced in the near future, he explains. Producers will be looking for flexible systems that enable them to serve their customers better, and this will mean more MES tools.

Another driving factor, Leffler emphasizes, will be the merger and acquisition activity of the last decade. Companies such as Willamette Industries, which have been built by acquisitions, will decide on new systems and new tools to run their business. In doing so, they will look for ways to tie together all the businesses, from wood and wastepaper handling to converting. Companies will seek to cut out whole layers of current activities with a view to being leaner and more efficient.

In terms of where MES will take root first, Leffler sees Europe and the U.S. ahead at this time, but agrees that Korea and Japan are already very advanced in Asia.

SECTION 2: THE MOVE TOWARD INTEGRATION

In assessing where the paper industry currently is along the evolutionary path to information integration, Donald Clark, manager, TotalPlant product definition and introduction, at Honeywell, Phoenix, Az., explained that prior to World War II, the problems associated with handling a manufacturing process and managing its product were generally handled by the same person, called a craftsman. The people who operated the plant had a "gut feeling" about the product, and worked both ends very carefully. This was before any automation.

With the war effort came cost consciousness and associated production improvements. At that time a natural separation began between the world of the process and the world of product management, Clark says. This separation continued until about the 1970s, when two completely separate worlds emerged."

At this time, two distinct control thrusts entered the scene--one in the area of process control and the other dedicated to information management, typified by the mainframe computers supplied by IBM and later by Burroughs, Hewlett Packard, etc. During the past 20 years, this control separation has continued to widen. The business systems have been trying to provide off-line cost models, completely detached from the process world. And the production side has been concerned only with pressures, flows, temperatures, etc.

With the escalation of competitive world market pressures in the 1980s-90s, the industry has been forced to look at ways of doing business differently. Suddenly there is recognition that two worlds have been mistakenly and unnecessarily driven apart. "What we need now," Clark says that the industry is asserting, "is to return to the good old days of the craftsmen, who have intimate knowledge of the process and an understanding of the business aspects behind it. So in the current move toward information integration, we seem to be going more or less full circle."

The rejoining of these two worlds, Clark concludes, is going to require an ever increasing amount of applications technology, or information processing packages. Greater and greater amounts of input information will be required--not just process data such as temperatures, pressures, flows, etc.--but measurements of properties, things about the products that customers and consumers care about.

"That kind of information will have to be brought in to run against the applications packages in order to manage the business better. In that regard we think the opportunity exists for something much better in the near future. We are very bullish, for example, on fieldbus technologies that will allow these kinds of information to be acquired at a much lower cost," Clark says.

HALFWAY THERE. In Leffler's view, the world paper industry is currently about halfway through the automation-information revolution. "The ground floor has been laid," he says. "Almost everyone has DCS and QCS systems. They have the basic database in place. What we have to do now is to turn those thousands of signals into meaningful information. It is on the information level that the next revolution will come, with management execution systems."

Leffler believes that MES is also a matter of empowering the operator. Systems gurus are available in the mill for a mere 25% of the time. In general, they are not available at night or on weekends and during holidays. It is the operator that must keep things running for 75% of the time. That, says Leffler, means giving the operator better information, so that he or she can play more roles.

Leffler says that the tools are available today to move towards MES. For example, the operator can currently call up AutoCad computer-aided design systems or data concerning the maintenance of the production line. The challenge is to build the integration of these systems in a way that enables the operator to make business decisions.

As an example Leffler cites a tool developed by ABB called PAS or Product Assessment Software. This package enables the operator to see quality data on the entire reel on one screen (60,000 data points obtained from the scanners). The operator can then pull out the various customer specifications and compare them with the reel.

This allows the operator to decide which part of the production should go to which customer, something previously done by the supervisor--in effect, it is the transition from operator to businessman on-line.

THE TIME IS RIGHT. John Weeks, vice president, automated systems div., Rust Engineering Co., Birmingham, Ala., also believes that the time and conditions have finally come for the paper industry to move forward into full information integration. When he talks about the industry's "dream" back in 1982, he is referring to "millwide control," an elusive goal that was literally discussed into the ground at hundreds of industry conferences and seminars, and over-editorialized in at least as many industry magazine articles.

"Everywhere you looked," Weeks recounts, "you saw a pyramid--presentation after presentation after presentation. All of these structured, well-planned pyramids were supposed to lead to millwide control. But except for a few isolated cases, it never really happened."

While mills during the 1980s became less "separate" and "divided" than in prior years, they never experienced true millwide integration, Weeks says."But I believe the dream that began more than a decade ago will finally be realized--in the very near future," he proclaims.

Millwide control, Weeks goes on to explain, is now rapidly evolving into EI or MES. At its Birmingham, Ala., headquarters complex, Rust has set up an EI center to demonstrate "how the integration of process control, manufacturing execution, and business planning systems can be used as a competitive tool."

Bill Weyand, executive vice president, worldwide sales and service, Measurex Corp., Atlanta, Ga., asks the question: "Where was the return on all those millions of dollars spent for millwide control in the 1980s?" It was basically investment in "technology for technology's sake," he contends--mills not really knowing what they wanted to get out of these systems.

"Mills today are looking for solutions to particular problems or issues, which, of course, is the right approach. That solution could be a quality gathering software package from somebody, and the mill could sprinkle some individuality into that, for example. But they're not going to have a lot of programmers in the back room.

"Mills will be investing in solutions to specific problems in all papermaking areas, including pulping, quality tracking and control, roll tracking, shipping and customer satisfaction, environmental, etc.," he says. And that will require extensive integration of information from all levels.

These solutions, Weyand believes, will come from many companies now heavily involved in research and development, some that are unheard of today. "The barriers of our systems are being peeled off, like it or not. With LANs and open architecture, the same PC that the mill manager uses for his purposes can be used by the control engineer or the person in the quality control lab for their purposes--for anything from the process or the business side. "That's a major evolution," he declares.

Bailey Corp. also sees the trend toward integration of a mill's management information side with its process control side as a "major growth avenue" for the future. Brad Loewen, manager of the pulp and paper group for Elsag Bailey Canada Inc., says that the trend now seems to be towards client-server architectures, where the client is a PC on a desk running perhaps Microsoft Windows.

The server of the data, or information, is either directly interfaced to the DCS where there is a historian function, or it is an independent data gathering system installed separately by the mill. "We see the role of the historian--the data server, if you will--as being a better fit for the DCS," Loewen notes.

The historian function, regardless of where it resides, takes snapshots of process data and stores them away in some time-sampled fashion for reconstruction and comparison at a later point in time. A key issue right now is the resolution or fidelity with which data can be stored and accessed, Loewen explains. One of the weaknesses of some of the older systems was the need to "filter" data considerably to fit it into available technologies. As a result, mills typically were ending up with a 30-min average fidelity.

"Today, using some of the modern sampling software, data can be stored and replayed at the same resolution that the operator sees it, which means down to one second or better resolution--when the historian is native to the DCS," Loewen reports. Bailey just released its historian for the PC, called Real Time Server, or RTS.

"I was at a mill in northern Ontario recently that had more than 300 PCs in various offices." Loewen relates. "Almost every employee in the administration and management side has a PC tied to a local area network, and the demand for linking up this MIS system with the real-time world of DCS is very strong."

THE PAYBACK FACTOR. Spending for process control and information maximization is not necessarily tied to capital expansion monies. A few years ago when paper company profits were sagging around the world, some progressive companies continued efforts to more fully integrate their control networks, despite "unhealthy" bottom lines.

The key in almost every case has been "justification," or perhaps the more profain term, "payback." Even in economically better times, payback is still the prime consideration when paper companies invest in control and information technologies.

Peter Zornio, strategic product planner for Honeywell's industrial automation & control div. in Phoenix, Az., says that views have changed dramatically since the 1980s, when mills felt that "all of these systems are really great, and if we just put them in, and all of this information is available to everybody, good things will automatically happen." Now there is a strong demand to prove the value of everything, he emphasizes.

As Ole Fadum, president of Fadum Enterprises in Boulder, Col., has shown, figuring payback can be an inexact and tricky experience. While his investigations have clearly indicated that the mill with a higher level of control is generally more profitable than a comparable one with a relatively lower level of automation, he is quick to point out that process control is only "the art of the incremental."

Process control, according to Fadum, doesn't determine the absolute level of anything. The prime determiners are mill location, labor contracts, raw material costs, energy costs, how old the process equipment is, how well it's being taken care of, etc. Process control can only fine-tune these variables.

"Information technology, on the other hand, can have a direct, measurable effect on a mill's operating efficiency and profits. If information is used right, it can determine the best operating targets, and impact the bottom line in many different ways," Fadum explains.

Mark Davidson, director of marketing for information technology and applications at Foxboro in Massachusetts, points to "simplicity" and "essential information" as keys to justifying further expenditures for process and information control. "The challenge is to provide information in a very simple way that people can understand," he says.

"We need to avoid large volumes of data, and maybe just focus on trends or numbers with an arrow that says this direction is good and that direction is bad. Noise has to be filtered from data so that operators have just essential information. This could help eliminate many of the time-consuming, costly training issues.

"Management typically will only care about getting employees more and better informed if they see direct results related to productivity, quality, lower material and energy costs, etc. So it is crucial that operators are able to easily understand the user presentations of an information system and be able to measure and quantify improvements for management," Davidson emphasizes.

The need for simplicity is echoed by Torbjorn Herngren of ABB in Sweden, who says that a recent trend is to provide product information systems where the product properties and trend data are very "visible" to operators. As an example, he refers to information provided as "an easily understood map" now being used by some mills to program slitting and sheeting operations to minimize waste and meet customer needs.

Geoff Lawrence, vice president of marketing for Impact Systems, San Jose, Calif., sees the advent and increasing popularity of such non-proprietary "man-machine" interface programs as Wonderware and Factory Link as major contributors in improving process "visibility" for operators. "These systems are extremely operator friendly and highly intuitive," he emphasizes.

Because the goals and objectives of each mill is a little different, Lawrence explains, a great deal of individual flexibility and openness is needed to design and use an information system around what a specific mill deems most important. Some of these man-machine interfaces allow that flexibility and provide "simplicity" of operation. "It's one thing to empower operators with on-line information, and another thing to have them easily understand and use it," he comments.

Paul Collin, senior consultant for Foxboro, adds that the payoff for enhanced information technologies could, at least in part, be viewed as compensation for the flow of information lost in the industry's "re-engineering" or downsizing efforts of the past few years.

"These efforts have greatly reduced and in some cases eliminated the flow of information to operations, or for that matter management, to help them make intelligent decisions 24 hours a day. With the reduction of people goes a reduction in information and information transfer. Information systems can help fill these voids, seamlessly and reliably," Collin states.

Weyand of Measurex points out that in the past, decisions involving process control and information systems were basically in the hands of control "technocrats," because production and management people did not really speak the language and did not know the technical ins and outs of computerization. But the control experts did not have the background to know what was right for the machine, or the product, or even what the mill was trying to accomplish in the first place.

As a result, mills invested in technology bells and whistles but did not get a good return on investment, and in some cases no return at all. Weyand explains that "in the future, production and mill management will become more actively involved in these investments, and will be asking questions such as, 'how does it affect product quality?'...'how does it affect machine or process efficiency?' If its doesn't improve these two issues, then it's not a good investment. Team thinking versus specialist group thinking will be the trend of the future," he proclaims.

CHANGING ROLE OF THE OPERATOR. Which roles will MES prepare operators of the future to play? First, and perhaps foremost, Leffler sees the operator as a "businessman on-line," empowered to decide which tonnage fits a customer's requirements and to have it shipped on his own authority. "This used to be done by the supervisor," comments Leffler, but now we have the tools and the information to empower the operator to do it.

Other roles Leffler sees as belonging to the operator of the future are quality controller, production manager, environmental guardian (this means giving the operator tools to understand the mill's total operation, including environmental restraints that might be imposed on other parts of the process), and first line of maintenance.

"All of this creates a very responsible job," says Leffler. "And with that highly responsible job, it becomes possible to employ more highly-educated people into the industry." Cultural and geographical differences then start to come into play. Leffler says that the Nordic countries are ahead in empowering their operators to do bigger tasks, and quotes the merging of maintenance and operational teams as an example.

"Some U.S. companies, like Weyerhaeuser and Willamette Industries are also moving fast, but there is more variation in approach. But in Japan, for example, it is difficult to find people of the right educational level to work in the mills," Leffler explains.

If the educational level of the mill staff can be raised to BA degree level, and full advantage of MES taken, Leffler believes that the supervisor's role of today will be eliminated and the whole philosophy of the mill changed. He says: "Mills will not be trimming their operations, but rethinking them from scratch. Downloading (and uploading to senior management) of some of the tasks of the supervisor will allow mills to get rid of a layer of supervisors. This is one way in which mills can compete with new Asian companies that have break-even points 20%-30% lower than their western counterparts."

Ingman explains that some greenfield mills have tended to move in the opposite direction in recent years. These mills, he says, were started up with only a small number of experienced pulp and paper makers to manage or "back up" a large staff of operators generally taken from gas stations and corn or cotton fields. The operators were carefully trained, establishing a new, high-achiever work system, supported by psychological testing, team structures, etc.

"The initial reaction has been pretty good, but the final report is not in yet. In my opinion, this could eventually result in an unfair burden on the small group of experienced personnel. They become so crucial to the operation that the mill's success is totally dependent on them. Everything is fine as long as things run smoothly, as long as the same thing happens today as happened yesterday and the day before, etc.--as it was when the operators were trained.

"As situations repeat, which the operators know very well, they can handle them. But the operator were never trained to know what makes a pulp or paper mill really tick. So when a new situation comes up, no matter how fabulous their team spirit may be, they won't be able to handle it. The problem will fall on the shoulders of the handful of experienced people that work around the clock, year around, and have to make all of the tough decisions. I believe this will burn them out eventually," Ingman asserts.

Zornio points out that it is a misnomer to call today's operators "operators," because, in reality, they are actually "fire fighters." They are there for when something goes wrong--"the abnormal control system that takes over when something happens that the standard control system doesn't know how to handle.

"Today, a mill's PID loops are 99.9% on uptime. The next step is to get that same percentage of uptime at the production level. Then the operator becomes what today is called a superintendent, dealing with cost, quality, schedules, etc. That future operator won't have to worry about how to kick a pump to get it to restart. That knowledge will be encapsulated, if you will, in the control system, just like the first level PID control stuff has been encapsulated today," Zornio insists.

SECTION 3: ADVANCES IN SENSOR AND CONTROL TECHNOLOGIES

Most efforts to improve control of the paper machine are being focused directly on the wet end. The need for real-time information from this critical zone of the paper machine has spurred several on-line sensor developments in recent years, including opacity, ash content, color, freeness, smoothness, formation, etc.

On-line fiber orientation sensors and fiber length analyzers may soon be available, providing real-time information on cross-machine and machine-direction strength and allowing more effective stock blending. Accurate and reliable consistency control is also in the works, with several new nuclear-and microwave-based devices now approaching commercial reality.

As Ken Kornegay, senior process controls design engineer, BE&K Engineering Co., Birmingham, Ala., explains, traditional consistency transmitters have been basically unreliable, and were never really used for absolute readings. About all these units could do was provide trending information--let operators know if consistency was going up or down. For advanced stock prep/wet end control, however, highly accurate consistency data will become progressively critical.

The newer units appear to be not only accurate and dependable, but also have a relatively fast response time and are not as susceptible to problems caused by changes in the furnish stream, Kornegay adds.

Robert Price, manager-process control, automated systems div. of Rust Engineering in Birmingham, Ala., points out that the microwave transmitters are considerably more expensive that the nuclear-based units. Both units have some limitations. For example, the microwave transmitters, being pressure sensitive, require collapse of air bubbles from the stock before a good reading can be made. And sometimes the pressure has to be jacked up without a direct process need.

Ole Fadum insists that there is a very basic, fundamental need in the paper industry for more and better sensors, particularly for the wet end of the paper machine. "The next paper industry frontier is going to be wet end related," he says, "and it's going to involve wet end chemistry, refining, stock blending, etc. The need to know more about the quality as well as quantity of fibers will obviously become more and more important."

But measurement is one thing and control another, Fadum continues. An example, he cites, involves efforts to control elusive strength parameters. "Strength is not a one-for-one situation, as is basis weight, which is generally controllable by a single valve. Strength control is multivariable, requiring the manipulation of several process conditions simultaneously."

The same is true to varying degrees with retention, freeness, ash content, color, etc. Color, Fadum points out, is a very competitive area where a lot of work has been done recently. "ABB's color work with Beckett Paper has been very successful," he says, adding that Measurex has also "refurbished" its color control recently. "Color used to be a single-point measure, but now it involves scanning to get the average of the whole sheet. But the thing is, we haven't yet found a way to control color in the cross direction," he explains.

FROM MILL LAB TO ON-LINE. The move toward more real-time information at the wet end is in line with the industry's emphasis on designing quality into systems and processes rather than inspecting it at the end of the production line. In this regard, the role of the mill testing laboratory has been changing dramatically in recent years, and will continue to evolve well into the next century.

The trend toward empowering operators to resolve quality problems and be responsible for inspection, as well as to control costs, is sometimes bringing the mill lab--previously the sole arbiter of quality--into conflict with the production department. In many mills, the role of tester has been physically moved to the production arena, in the form of automated testing systems such as Valmet Automation's PaperLab, the Autoline by AB Lorentzen & Wettre, and the Testline by Messmer Buchel.

Although not truly "on-line," such fully automated systems do dramatically reduce the lag of information to operators. They can cut total testing time by as much as 80%, freeing up mill lab personnel for use elsewhere in tracking down and preventing quality problems.

According to Valmet Automation's calculations, laboratory testing is a highly labor intensive skill, with 16% of a tester's time typically being spent on sampling, 9% on preparation, 37% on testing, 14% on taking readings, 19% on recording results, and 5% on calculation.

Information collected by automated testing systems is generally fed into a mill's MES, MIS, or EI system.

WET END INFORMATION SYSTEMS. A leading paper chemical supplier in Finland, the Raisio Group, has developed a wet end information system that can increase the efficiency of paper and board production by several percentage points. The new system merges measurement technologies developed by Raisio with Wedge data analysis software from KCL.

With this system, samples are taken and analyzed from three to five places along the wet end at 20-min intervals. Parameters measured include silicate, calcium, aluminum, charging state, turbidity, DOC, conductivity, and pH.

The system is controlled by Simatic 115U programmable logic. Each sample line and analyzer is independent, increasing the robustness of the system. Control software is equipped with a graphic user interface, and the display shows status data of motors and valves as well as process measurements.

Measurement results are stored in memory and used as data or processed to control the paper machine. Custom designed daily and alarm reports are also produced. The system can be connected to the MIS network.

The first unit recently installed in Kaukus Oy's Voikka mill is expected to boost runnability and product uniformity significantly. The mill anticipates that problem analysis will also be simplified, resulting in less downtime and considerably reduced broke. Additive efficacy can also be assessed more readily with the system, and dosages optimized.

The optical-laser based Chemtronics retention monitoring units developed by Eka Noble have been installed on nearly 100 fine paper machines worldwide during the past few years, and more installations are planned during the remainder of this decade.

Paul Coates and Ian Green of Eka Nobel in Sweden explain that the optical laser sensor gives measurements of total solids and mineral filler concentrations. By using the sensor in the flowbox and backwater, overall retention and fiber and filler retentions are calculated.

Some mills use the laser sensor for monitoring. Others use it as a process control tool by keeping the backwater solids content fixed. An adaptive control algorithm is used to vary the retention aid dosage. In some mills this is not practicable because of the volume of water in the backwater loops and the long time constants in the system. Similar systems are supplied by Valmet Automation, BTG, and Boliden in Sweden.

The laser sensor includes a pump to ensure constant flow through it and to break up flocs that would interfere with the accuracy of the measurement. In the latest version, flocs are allowed to form and a stock flocculation index is produced. This feature is speed and machine sensitive. On the three installations in Sweden, the flocculation index correlates well with dry end formation measurements.

One of the older optical-laser sensor systems is used on a deinking line at Bear Island Paper Co.'s newsprint mill in Ashland, Va. Installed around the flotation deinking cells, it is used to monitor and control brightness. Future developments will concentrate on the flocculation sensor and control system, according to Coates and Green.

FLOCCULATION CONTROL. Glen Havelock of Pira emphasizes that control of flocculation can solve many of today's paper and board production problems, "impinging on process economics and product quality." Controlling flocculation of fines and fillers, he points out, leads to increased retention, reducing the waste of raw materials, increasing closure, and reducing water consumption.

Controlling fiber flocculation, he continues, reduces variability, leads to fewer web breaks, and results in improved formation, smoothness, overall strength, etc. But since current mill practice relies on laboratory quality testing results, by the time a flocculation problem is identified, it might have disappeared or become worse.

Flocculation, Havelock insists, needs to be measured on-line so that appropriate action can be taken at the right time. But mills currently are limited in the action they can take. Changing the chemical balance can seriously impact other aspects of the process. The only real course of action is to reduce headbox consistency and/or production rate, the latter being undesirable and often unacceptable.

Most elements for automatic control of flocculation are currently available, he points out. These include the sonic roll, which can be driven independently of wire speed, and chemical agents that can be used to change flocculation conditions.

Flocculation sensors that produce a signal proportional to the optical or mass density solids in the wet web or in suspension are also available. Control algorithms capable of handling the problem exist, as do advanced process simulation tools and statistical processing methods to model the complex process dynamics of the wet end and its water circuits.

Until now, a stumbling block has been the uncertainty of what it is about flocculation that needed measurement and control, Havelock explains. This problem has been partially resolved in a project funded by the European Commission and companies undertaken by TNO (Europe's largest R&D center involved in process control, automation, and sensor development), Holland, Pira, UK, and IPE/Univ. of Madrid.

In pilot plant studies, excellent correlations were found between wet state flocculation results and finished sheet properties of smoothness and formation. The potential exists for the machine operator to control flocculation by entering set-point data as product property requirements, Havelock reports. The next step is to validate the pilot plant findings, and TNO and Pira are seeking mills to participate in this stage.

AUTOMATIC GRADE CHANGE. As Herngren of ABB explains, the current emphasis in the paper machine room as well as the pulp mill is on flexible production and shorter run lengths. TNO is actively working with Dutch paper companies to transfer proven technologies for other industries that will reduce the time taken for simple grade (grammage) changes in fine paper mills from 6-8 min to 3 min. Currently, an average 1% of production capacity is lost during these changes. This is likely to increase as the length of production runs shortens.

The approach under investigation by TNO and the Dutch paper companies involves multidisciplinary teams and all staff within a mill. Shift activities are filmed and examined by a research psychologist with the aim of determining current practice. Understanding the reasons for differences leads to the identification of future best practice. This is then included in the software for an automated grade changing system.

According to Fadum, automated grade changing generally requires either a very interfaced system or a very integrated system, meaning that a mill must have a DCS as well as a sensor-based system. A coordinated grade change has to be controlled from stock preparation all the way through, he stresses.

"Nobody wants to do frequent, short production runs because of the losses," Fadum points out, "but customers and the marketplace in general are beginning to demand them. A production manager at an east coast mill told me that he recently got an order for 150 tons of product, but lost 50 tons in going onto the product and 50 tons leaving it. The result was a rather unprofitable run for the mill, since the cost of the losses couldn't be passed on. So something has got to be done to better control grade changing."

One of the first grades necessitating a "grade change" to meet different customer specifications on a single machine was newsprint, according to Ingman of Valmet Automation. "Not too long ago there was only one newsprint grade in North America. Then USA Today began requiring a different sheet because of its color printing.

"Then a lot of other newspaper companies decided they were also important, and began ordering with their very own, custom specifications. Suddenly we had 10 to 20 different newsprint grades--or as many as there were big influential buyers. Parallel to this, the same thing started to happen with packaging grades, linerboard, and then fine papers.

"Grade change technology is basically software modifications," Ingman maintains. "We have most of the basic tools today, such as on-line fiber length analyzers, that will be needed to make this happen. But, actually, it's difficult to see how a lot of major grade changing can ever be truly economical. Mills will continue to do more of it just to get and keep business. But a mill that has real-time cost analysis and control will probably be in for a surprise when they really examine the profit picture."

Weyand of Measurex agrees that a lot more on-line sensor technology will be applied to the paper machine in the future to keep up with specific customer demands. "The days of weight, moisture, and caliper are pretty much over," he believes. Soon there will be as many as 10-15 different real-time measurements coming off the paper machine relating to quality characteristics of the sheet. "And there is high interest in being able to not only measure surface qualities, but automatically control the grade changing to effect certain ones," he adds.

PULP MILL/CHEMICAL RECOVERY. In the chemical pulp mill, considerable on-line measurements and control have been commonplace for many years. The most recent analyzers are for on-line kappa number, being used extensively to track efficiencies of oxygen delignification stages and to follow pulp to and through the bleach plant. Fewer than a hundred of these units have been installed thus far, not nearly up to expectations of a few years ago when they were first introduced.

Monitoring and control developments for the pulp mill and bleach plant will continue to focus on cooking conditions in the digester and washing and chemical efficiencies throughout the fiberline. As mills settle on environmentally sound non-chlorine bleaching strategies, the next step will obviously be effluent closure, which some mills are already exploring. More and more information will become critical as this trend develops.

Mike Pemberton, industry director-pulp & paper, Fisher-Rosemount in Birmingham, Ala., says that one of the first major on-line analyzers his company developed was for active and effective alkali, based on work being done at Auburn Univ. in Alabama in the mid-1980s. "Since then, we have been exploring a lot of specialized sensor potential in the pulp mill, and are currently developing a residual cooking liquor sensor and a sensor for measuring lignin, not after the blow but continuously on the digester and recirculation line," he reports.

This technology, Pemberton explains, uses continuous near-infrared (NIR) measurement of lignin content in the cooking liquor at various stages of the digester, indicating relative and total efficiency of the cooking process. This could be particularly effective with what is being called "low solids cooking" in continuous digesters.

One development area that Pemberton believes could have a major impact in the pulp mill is sensor fusion technology, where several sensor capabilities are incorporated in one unit. For example, viscosity requires a mass flow as well as differential pressure.

In recausticizing, "the kinds of measurements needed are nuclear density and conductivity (actually NIR has been used effectively in this regard). Sensor fusion will help control the cost of acquiring process data, and improve overall capabilities and reliability," he emphasizes.

On-line chip moisture content, as well as chip species, are among the high priority needs cited for the pulp mill at this time. In the chemical recovery loop, an area Pemberton sees as also having high on-line sensor potential, some of the priority needs include total reduced sulfur (TRS), opacity on boiler and kiln stacks, black liquor heating value, sulfide analysis, organic loss, and possibly AOX. On-line measurement of chloride levels in black liquor is another critical future need, as is liquor droplet size.

SECTION 4: MILL AUTOMATION AND CONTROL STRATEGIES

The following medley of control practices and strategies at 10 mills around the world illustrates various approaches being used to solve specific problems through information integration and optimization. As a sampler, it is not intended to represent a cross section of technology or indicate trends in the use of any particular systems or equipment.

Hansol Commits to Total Integration of Korean Mills

Hansol in South Korea is the largest paper group in Korea and has led the world in adding paper machines during the past three years. Products range from premium specialty/color grades (Petech mill) to newsprint (Chonju mill), fine printing and writing papers (Changhang mill), and paperboards (Taejon mill). The company is highly committed to the "total integration of information" at its four mills.

As Hansol's Kae-Sung Baek, corporate general manager for factory automation, puts it: "To meet our ambitious present and future goals, Hansol cannot afford to invest in automation technology without knowing how well it fits our total company-wide information network philosophy. Open system architecture and smart technology are obviously very important to us--to even qualify our vendors."

ABB began working with Hansol in 1991 and in 1992 installed quality control and sheet inspection systems on the company's large No. 6 newsprint machine. This system included ABB's futuristic Advant Technology, the first Asian mill to employ it. Based on the success of this project, ABB has since installed several automation, sheet inspection, and electrical drives systems at all four of Hansol's mills.

No. 6 machine contains ABB's Smart Platform with Smart basis weight, moisture, and caliper sensors, as well as Smart CD controls and actuators and the ULMA 3D web inspection system. Including ABB, there were a total of six suppliers of electrical and automation systems on this project. As a result, although these systems all perform well, there is no integration of information. In effect, the whole plant is still a cluster of many information islands lacking integration and distributed communication between segments of the mill.

ABB strongly advised, and is working with, Hansol to adopt "Total Integration Path" for their future projects, and to start working towards bringing their existing plants under the same information integration umbrella. Total integration means bringing all of the critical measurements, controls, electrical (drives, etc.), logic (PLCs), regulatory (DCS), and supervisory (QCS) information together on a unified mill network, to allow process information to be easily mixed and used with accounting, financial, and cost information for optimum profitability.

Earlier this year, ABB was awarded orders for fully integrated systems (QCS, DCS, drives, web inspection) orders for Hansol's two new fine paper machines at Changhang and another large newsprint machine at Chonju.

Highly Integrated System Pays Off for Portuguese Mill

The Soporcel mill in Lisbon, Portugal, produces 420,000 mtpy of bleached eucalyptus pulp, 170,000 tons of which is captive to its 265,000-mtpy uncoated free-sheet line. The paper machine for this grade operates at an average speed of 1,060 mpm.

A key factor in the success of the paper mill, according to Soporcel's Carlos Vieira, is the integrated $7 million MIS system linking 13 mill activities. Supplied by Measurex, the system receives input from production programming, materials purchasing, paper machine control, roll production and tracking, intermediate roll storage, finishing programming and order tracking, finished goods warehouse, order dispatch, customer advice and invoicing, financial control, and management data.

The mill staff was well trained on the MIS system's operation and its underlying technology during installation. This allowed the mill to develop the basic functionality of the system to give better internal reporting and commercial data.

At the machine level, all departments are linked by the DCS to provide a single window on the process. The Measurex SuperVision system controls basis weight, moisture, and color. Paper machine performance is monitored by the Safecontrol condition monitoring system.

The mill is seeking to improve its wet end control, where it uses a dual-poly retention system. Its philosophy is to first monitor to obtain data, and then use this information and knowledge before adopting an automated control system. Retention is currently monitored using on-line Kajaani sensors to obtain data prior to feedback control on backwater solids content. The mill also monitors stock charge off-line.

The driving force behind many of the mill's control investments has been the need to provide high levels of service in a demanding market. Finishing and dispatch are fully automated to provide the service and flexibility demanded by the market.

The mill has two automated warehouses, one for process reels and the other for finished pallets. A feature of the finishing department is the lean flow and use of automatic-guided vehicles (AGVs). The air conditioned process reel store decouples the finishing department from the paper machine, allowing reels with specific properties to be retrieved to meet customers' requirements. Reels leaving the store are automatically directed by an AGV to the correct finishing line.

The palletized goods store is served by robotic handling machines. Each pallet is bar coded and the fork lift trucks are fitted with a decoder. Wiping the barcodes produces instructions on positioning the pallet in the warehouse. This makes retrieval of cut sheets easier to match customer requirements.

Distribution is a critical competitive factor, as most customers require information on the time a delivery can be expected. The mill has resolved this by satellite links with its trucks enroute to customers, who can know within an hour of when to expect the delivery. Another advantage of the system is that trucks can be routed around traffic hold-ups, reducing both delivery time and costs.

Weyco Mill Well Along Road to Full Info Integration

Weyerhaeuser's fine paper, linerboard, and market pulp mill in Plymouth, N.C., is beginning to reap the benefits of a fully integrated production information system that got underway in early 1994. The mill has been undergoing extensive expansion and upgrade projects during the past few years, including a fiberline rebuild with two new continuous digesters as the centerpiece and two major paper machine overhauls, as well as other extensive upgrade projects.

The mill's DCS system was supplied by Bailey, and Measurex scanning platforms and wet end control are installed on the paper machines. The fiber optic network "backbone" is a dual-ring arrangement, with extra fibers that allow it "to go either way," according to Alice Winslow, information technology manager at the mill. It operates at 100 megaB/sec. Each location or operating area has Ethernet, a lot of which is fiber optics. The systems runs on a Hewlett Packard model 9000 Unix system. The software used for graphics, trending, etc., is Cim21.

When the mill began efforts to upgrade and better integrate its information systems about a year and a half ago, five goals were set, according to Gene White, controller. These were to maximize worker safety, customer service, product quality, housekeeping (including environmental), and production costs. "Basically, our plan was to empower operating level people with whatever information is necessary to make decisions that will accomplish these goals," he emphasizes.

Debbie Tadlock, acting fiberline manager, discusses how the system works from an operator's perspective. Each person uses the "hello" system to "click-on" screens that allows them to understand, within 5 min, what is happening in the fiberline--what is important.

"What we wanted was an information rich environment for our operators," she emphasizes. "First, this meant making sure we had the right kind of instrumentation in the field, that the sensors were located in the right places, etc. We needed to know what was happening real-time, all the time.

"The second ingredient was the business information, so that operators could clearly understand 'why' something needed to be done as well as 'how.' The third element of our information rich environment was a physical work environment that allowed for easy communications. In some cases, this meant locating teams in certain areas together," Tadlock explains

Winslow adds that a fourth prime ingredient was development of the right "culture" at the mill. "We had to bring the operators to the level where they feel that they can take responsibility. I think we're at that level now," she says.

The mill's hourly and maintenance personnel are probably most advanced in the use of the system, according to Tadlock. "They use the "Prism" business system as much as management does. They can understand where their costs are on an index basis, and they can explain to management where they are against expectations.

"They can look at chemical costs, fiber costs, raw materials consumption, water, utilities--on a by-shift basis, averaged in various ways. Before the end of the month, if they find out they are not doing so well, they still have time to react and correct things. They are in constant communications with the quality variables, and have a "visible' understanding of customer needs and specifications.

The system also can be used for predictive analysis and reporting, Larry Penn, process systems manager points out. The mill already has the ability to alert people that problems are coming their way. In the future, he adds, the mill will be working more with this capability so that the various process segments work together to control and work-around upsets.

All areas of the mill are integrated into the information network, from the woodyard (chip test data and other information) to the powerhouse, pulp mill, paper machine, and finishing and shipping. The mill has an inventory management system for both the brown and white paper grades. Orders are received automatically from the company's respective divisions.

Aylesford Newsprint Bases PC Needs on In-depth Study

The Aylesford Newsprint mill at Aylesford, Maidstone, Kent, UK, a joint venture of SCA and Minorco, recently invested ú250 million in a new fiber treatment plant, a new 1,600 mpm machine with 9.2-m trim, an automated warehouse, and environmental control measures. Spending for process control and automation equipment and the supporting infrastructure was in the range of ú10 million, according to Valter Kornfeldt and Mike Terry of the mill's project team.

In specifying the process control system, the mill first determined all information needed to control the entire operation. It carefully measured all parameters and assessed exactly what information would be needed by everyone within the operation to fulfill their roles. A usable, networked, open system was essential. Fieldbus was examined and rejected for lack of experience with this technology in the paper industry.

At the center of the complex information and control network is the ABB supplied Production and Quality Management System (PQMS). This has sales, production planning, and control and information systems modules. The latter contains information on customer reels, archive material, and data bases. The PQMS interfaces with the process control and subsystems used in finishing and the warehouse.

The PQMS has extensive report generating capability. It could be used for monitoring more sophisticated environmental performance parameters should the need arise. Technically minor modifications are required to link it with customers' systems to provide a "dial-in" grade service.

The QCS/DCS process control system supplied by Measurex covers the site. It controls the fiber preparation plant, the paper machine, the water treatment and effluent plants, and the sludge combustion plant. It also interfaces with PLC systems embedded in the plant via specific links or network connections. All electrical equipment--motors, pumps, air conditioning, etc.--is controlled by the Measurex system using Unilogic to respond to output from the PLCs.

A Cambridge Control system is also used for optimization of the fiber preparation plant. Flexibility is built into this so that optimization can be varied on throughput, quality, and eventually cost. The L&W Autoline installed in the mill laboratory is a stand-alone unit linked to the millwide network. The Maximo maintenance system is also stand alone. The information highway is parallel but linked to the Measurex system. The Ethernet runs at 10 megaB/sec, although it is rated at ten times that.

Some of the process equipment is linked by modem to corresponding suppliers to monitor performance. This has been particularly useful during commissioning and startup.

Training is a critical issue with 2% of the total project costs devoted to it. All staff are trained in tailor-made courses on the purpose and operation of the process and automation equipment. The initial stage is in the classroom, with access to simulators to demonstrate cause and effect. This is followed by "hands-on" experience during commissioning and startup. Some of the staff have been intensively trained by equipment suppliers to give them the knowledge to modify and enhance the system.

The basic problem in the fiber preparation plant is to cope with the variations in postconsumer waste news and "pams" that form the majority of the furnish. Installed sensors monitor consistency, freeness, ash, pH, conductivity, peroxide residuals, brightness, and speck count. The latter is particularly important for control of disperging stages.

The mill identifies this area as one where monitoring and control can be improved. The key is the development of robust sensors tolerant to the varying stock and dissolved materials concentrations likely to be found in a postconsumer waste furnish. Particular attention is needed on the measurement of consistency and pulp properties that impact on sheet strength and formation.

BTG sensors monitor consistency and ash content in the wet end. The output forms a control loop to vary retention aid dosage. Profile is controlled by the Measurex system using Jetmatic cross profile actuators.

A feature of the plant is its so-called "dark warehouse." This fully automated facility is a European newsprint first. It adapts technology more commonly found in tissue manufacturing and the most modern print houses. Essentially it is technology transferred from the distribution industry for pallet handling. Attention to detail is critical and extends to the design of loading bays and trailers.

U-C Shifts Information Network Project to High Gear

Union Camp's large complex at Franklin, Va., has a correspondingly large mixture of control systems, according to Henry Harris, engineering supervisor. In the paper machine areas, the mill has recently standardized on ABB systems. At this time one full paper machine is on DCS, and parts of three others are on the system. Graphics are generated with Cim21 software.

Overall, the mill has four distributed systems collecting data. And it is the engineering people rather than operators who are using the information at this time, Harris says.

The mill's LAN project now underway will make more information available at more terminals. Actually the project has been going on since the early 1990s, but Harris reports that efforts have increased lately and that the mill is projecting full operation by the end of this year.

"We essentially are covering every office in the mill with this network. And we have a group that is studying how to best empower our operators with all of the information, because that's where our payoff will come from," Harris believes, citing cost control and quality improvements as primary gains.

Currently the mill has an automatic paper test lab with terminals at the wet and dry ends of the paper machine. But Harris says that, although the backtender and the machine tender have access to the terminals and can use the information to make decisions based on the last reel, "still the terminals are over 'here' and the machine controls are over 'there.'

"We have to move forward with full information integration as soon as possible, especially with historical information for comparison. We have to get communications going between the paper mill, pulp mill, power plant, etc.

"Without shared information and communications, for example, the power plant, in a load shedding situation, will sometimes have to make a decision without knowing which machines are producing paper and which machines might be running the sheet in the hole. We have shut down some producing machines in these situations before.

"Operators, if they had the information, for another example, could ease into steam flow on the machine after a break rather than return to setpoint 'spike' conditions, without upsetting other systems in the mill--if they only knew these other systems were subject to upset. Also, a lot of titanium dioxide could be saved on the wet end with the right kind of information," Harris concludes.

The mill will also try to give more system information to sales and be able to investigate order problems as they develop, and to track orders through delivery. "One of the biggest problems with expanding and integrating information systems is justifying expenditures to management. It's really difficult if not impossible to say to financial people that you want $X million to invest and will be returning $X amount to the company as a result. No way," he proclaims.

Recycled Mill Chooses Advanced, Single-Supplier System

Sachsen Papier GmbH, started up in late 1994 at Eilenburg, Germany. Owned by Enso-Gutzeit Oy, the newsprint mill is one of Europe's largest investments based on recycled fiber. The mill's ABB Master DCS system with Advant Technology links separate systems that control and/or monitor:

. The recycling mill (power station, deinking line, waste treatment line)

. The paper mill (Valmet, 9.28-m-trim, 1,700-mpm paper machine)

. On-line quality measurements (internally referred to as Gerda) and

product databases

. Mathias (controls purchasing data and specifications, maintenance

schedules, and documentation)

. Franz (general administration and personnel)

. Production planning and general mill overview from the machine through

finishing to the warehouse (Robert)

. Environmental performance--gaseous emissions, aqueous emissions, solid

waste--and power consumption.

The system was completely installed by ABB, including a total of 27 Advant Station 515 operator stations and 20 Masterpiece 200 process stations with about 13,000 I/O. Data are transferred between Advant stations over a mill network on an Ethernet bus with a TCP/IP protocol. According to the mill, advantages of using a single supplier in this regard include:

. Reduced management and staff costs--the mill did not need to employ

systems development specialists

. The supplier's ability to provide virtually all of the components of

the system, the hardware and the software--all process motors were

supplied by ABB, as was the AccuRay at the heart of the Gerda system

. Simplified communications channels--only one company to deal with.

The mill's overall approach to automation and control is to ensure that at each management level and function, there is sufficient information available on which to make decisions. For example, the machine operators have information on production speeds, tonnage, quality, trim. and the status of each order.

The environmental monitoring system is more advanced than that required by German legislation. Emissions of dust, SO2, and NOx will be fed in real-time automatically to the legislative authorities. The mill believes this is important to establish trust with the legislators, which is best achieved by complete openness.

In the future, the mill plans to exchange business information with major customers, particularly production and quality data. Customers will also be able to determine through the production planning and monitoring system the status of their orders. The mill will also link into the central Enso sales system.

YFY Group Dumps Mainframe for DCS/Client-Server Setup

The YFY Group in Taiwan reports that beginning in the early 1980s, it used a centralized system on a proprietary mainframe, linked with smaller machines at its mills. The centralized system used an IBM 9221-15, 6 sets of DEC VAX mini-computers, and more than 600 PCs.

Shw-Uei Lin, manager of information management at the YFY Group, explains that the system "was functional, but was also very rigid and slow. Information did not reach our managers as quickly as they needed it." To maintain its leading position in the domestic market and to expand its export activities from June 1991, the implementation of a flexible DCS became a key component of the company's new strategy.

In March 1993, the YFY Group established its new open, distributed system based on the Informix-Online database connected to 700 PCs at each of its 10 manufacturing locations. The new system is tied to the mills through Informix-Star (distributed client-server environments).

Each mill runs a variety of applications, such as production management, inventory tracking, purchasing, materials management, and forecasting, that were developed using the Informix-4GL programming language. YFY's design incorporates a different database for each file server, and all of the programs are put in the client-server, called AP Client. The end user employs a PC as a system terminal.

A key benefit of the new system, according to Lin, is that it has given YFY Group's division managers greater control over their operations, from the ordering of raw materials to the shipping of the finished products. With accurate, timely, and comprehensive information readily available, managers have been able not only to increase efficiency and reduce costs, but also to respond more quickly to customer demands and developments in the market.

YFY is now planning to connect its system with those at more than 200 of its key customers and distributors, allowing them to check YFY's inventory and place orders directly from their own PCs. It is also exploring ways to use the DCS more efficiently at its mills, such as connecting the power plant together with the paper machine.

During 1989-90, YFY spent about US$2.4 million to establish CIM (computer integrated manufacturing) capabilities at its Hsin Wu board mill. This allowed a staff reduction of 30-40 persons, made the quality more stable, and increased production.

Willamette Customizes Extensive System at S.C. Mill

Willamette Industries' Marlboro Mill at Bennettsville, S.C., uses an ABB Master integrated control system consisting of 32 individual CPU centers (nodes) linked via an Ethernet communications network. The system handles approximately 16,000 I/O through a single window concept utilizing nine MasterView operator stations (technician consoles), according to David Avery, process control specialist at the mill.

To provide optimum efficiency in system management, the nodes and technician consoles have been divided into three networks or business units. The networks are connected through bi-directional communication gateways that provide millwide access from any MasterView station or any of 30 SuperView terminals (engineering terminals).

For the Marlboro mill, the integrated system is a single platform multiple process I/O (analog, digital, drives, PLCs, supervisory control--level 2, scanners, mill host computer, and other intelligent devices) together into one homogeneous package, Avery explains. This structure, along with the alarm/event handling capabilities, provides volumes of information on request. It also requires fewer technicians to monitor the operations. Externally integrated to the DCS system are:

. Cemscanner and fuzzy logic control for the lime kiln and slaker

. Hog fuel boiler burner management

. Incinerator burner management

. Kiln and recovery precipitator controls.

Internal to the DCS are: tank farm manager, digester scheduling, digester sequence control, bleach plant control, oxygen delignification, MD control (weight and moisture), and machine speed control.

Jim Myers, plant manager, points out that "we have put some upgrades on the ABB system, and deliberately kept everything in the Master. When we bought new systems, our philosophy was that we didn't want accompanying control--give us a logic and we will program it into the ABB. Now we have everything in the system, with a couple of exceptions," he explains.

Control for the RDH batch digester system was written by the mill itself using Beloit's logic, which had to be modified somewhat. In fact, all software used in the mill, "we designed ourselves," Myers emphasizes.

Myers believes that DCS suppliers should consider supplying "slick" management information systems that "ride on top" of their DCS systems. He refers to third-party systems that work on windows-type environments that PC users are familiar with, and says that "this is what they need to do--and help us keep all of the single supplier advantages."

The mill also has automatic grade change capabilities, which works well, Myers reports. "The biggest problem with grade change is draw. You can teach the computer to change the basis weight, consistency, fillers and other additives, furnish ratios, speed the machine up, slow it down gradually, etc., but because it doesn't actually 'see' what the sheet is doing on the machine, draw becomes a problem. Draw has to be monitored carefully when entering a grade change, and somebody always needs to be at the dryer section looking at draws.

"A 'catch-22' is that an automatic system starts to change gently so there won't be a break. But at the same time you don't want it to take three hours, because that represents a lot of transition production," Myers points out.

New QC System Sharpens Rohit's Competitive Edge, ROI

Rohit Pulp & Paper Mills Ltd. in Bombay, India, is a perfect example of what Asian mills are doing to continue to compete against smaller, older machines, according to Scott Morris of Honeywell-Asia. Rohit is a medium-sized producer of coated board and has been in operation for 20 years.

Rohit recognized the need to improve the quality of its product to give it a competitive advantage against these smaller, older machines. When the company decided to install a new quality control system, it spent considerable time evaluating what sensor technology would give the best accuracies. In particular, they were concerned about coatweight measurement.

The company evaluated traditional bone-dry differential and the newer infrared technologies, but settled on the gamma differential technology because of its higher accuracy (2% of coatweight versus 10%-20% for the other technologies) and less maintenance to keep it calibrated. The mill uses virgin hardwood and softwood and 80% deinked pulp as furnish, and wanted to minimize calibration requirements, reducing labor and potential error.

Because this was a considerable investment for the mill, given its capacity, it was also investing in ways to improve ROI. The mill decided on the Horizon Production Manager control package for supervisory control of the machine after evaluating results from other recent installations.

Horizon Production Manager is based on a mulitvariable predictive controller that allows the process to be controlled to much tighter tolerances and significantly minimizes grade change times over the conventional MD controls.

On-line Tracking System Keeps Pulp Production History

The need to improve mill performance, the increasing demand for customized pulp, a greater focus on quality, and growing competition in the pulp market were all key factors in Vallvik's decision to install ABB's Pulp Quality Footprint (PQF) system at its kraft TCF and ECF market pulp mill in Sweden. A member of the AssiDoman (umlaut over o) Group, the mill recently installed the system as part of a general pulp mill upgrade project, including the chemical recovery loop.

PQF, now operating at three pulp mills in Sweden, allows pulp production to be tracked through the fiberline. The system records the production history of a specific unit or "slice" of pulp as it makes its way along the fiberline, and stores it in a database. The 24-48 hr slice of production history begins with the chips in the woodyard and continues through the weighing of the finished pulp bales.

Typical data collected and stored would include type of chips fed to the digester, residual alkali when the same chips are halfway through the digester, kappa number in and out of oxygen delignification, brightness and other bleaching parameters within the bleach plant, etc. The pulp is usually divided into 150-200 slices, with a slice typically corresponding to 2-10 tons or 5-10 min of production.

Samples of the slices for laboratory testing are time stamped and entered into the database. A built-in process model takes into account any changes in production rates and levels in buffer tanks. ABB's Advant stations are normally used to run the mill model and database and provide operator interface with the PQF Software.

Operators, the quality department, and management can see what is happening in the various production stages, analyze problems, and take corrective actions. A variable tracking display shows how close a parameter is to its set value. With the PQF's mill profile display, the user can locate pulp close to specification limits. Up to four quality profiles can be studied at the same time.

PQF is proving to be a valuable tool at Vallvik, helping provide better overall control of production and improving pulp classification.

 

 

 

 

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