The giant Brazilian pulp mill links information management, quality classification and warehouse logistics
October 2007
By Mark Williamson
Keeping tight control over the quality and productivity of a mammoth fiber line is a challenging task for a pulp mill team. On-line, real time and historical data are valuable assets for managing the process and product quality, however, with today's high point-count process automation systems, automated quality verification systems, and extensive lab testing one could get lost easily in a sea of statistics.
To identify urgent process and quality issues and to plan long-term strategic improvements this vast of amount of data must be presented first in a simple, consolidated form to point out the problem areas and their effect. Then, with a depth of accessible information just below the surface, the problem-solving process can begin. With these tools, decisive actions can be based on clear knowledge.
Since its startup in May 2005, the 900,000 tonne/yr Veracel Celulose bleached eucalyptus kraft pulp mill in Brazil's Bahia State has made extensive use of Metso Automation's metsoDNA IA information management system while realizing positive steps in quality and productivity over the past two years. The mill management team, process operators, quality management staff and warehouse personnel have become "power users" of the system's capability since it was installed for the mill startup. Today, they regard it as an essential part of managing day-to-day operations and planning longer-term process improvements.
Veracel's industrial director, Walter dos Santos Martins says, "We use the Process Information Management System (PIMS) 24 hours a day, seven days a week. I even use it when I travel." Martins' most used desktop display and de-facto "home page" is the Process Operation Summary (POS), which consolidates recent information concerning quality, environmental measurements, production levels, liquor and pulp inventories and chemical consumption. He notes that the system information is transportable and securely accessible: "Even our shareholders have access." There are assigned users at Stora Enso and Aracruz Celulose, the two companies that each own 50% of the joint venture mill.
The PIMS defined by Veracel and implemented by Metso Automation is comprehensive in its scope since it combines information management, quality classification and warehouse management logistics. On one hand, it performs the typical functions of a process information system; it collects and consolidates process data and transforms this data into graphical displays, statistical charts and customized reports used to make decisions in morning meetings. However, PIMS goes much further since it incorporates laboratory quality test data and on-line quality measurements down to the bale level and uses this information to classify pulp lots into quality categories, which are then allocated to defined warehouse locations. Within the same system the movements of the quality-classified pulp lots are managed and followed through Veracel's delivery chain.
"Everything is interconnected, so it is a complete solution for our logistical chain," says pulp production manager, Guilherme Antonio Tedeschi de Araujo.
Information from chip filling to barges
PIMS is currently configured with approximately 14,000 data tag names that can be archived up to five years. Collection frequencies range from two seconds to 30 seconds. It is regularly used by 30 to 50 people at one time - from the fiber line, recovery line, chemical preparation, power plant, pulp drying and baling line, to the laboratory and the warehousing and shipping operations.
This requires several links of PIMS to other systems from various vendors in the mill. These include:
- The distributed control system (DCS)
- Energy management system (EMS)
- Turbine control system
- Baling line control and labeling system
- Scanning quality control system (QCS) on the pulp dryer
- pulpexpertDCD automated bale line quality sampling system
- SAP enterprise management and invoicing system, through a BEA interface system.
Bale-by-bale quality classification
Pulp bales from the three baling lines are packed into units of eight bales each. Bale lots are formed from up to 10 units. PIMS retrieves pulp quality data from the pulp dryer QCS system and a pulpexpertDCD which automatically samples dried pulp sheets every five minutes from the baling line and measures brightness, dirt count and shive count. PIMS also uses QCS measurements to produce a DNApaperMap display, which shows short term cross-direction and machine-direction grammage and dryness variability. Industrial information system specialist, Marcos Eduardo Leite, believes PIMS's ability to track pulp quality at the bale level is unique. These automated and on-line measurements are supplemented by laboratory tests to determine the pulp quality classification.
DNAbaleQM, the bale quality classification portion of PIMS, uses a matrix quality rating system to determine four categories of prime quality pulp, B-grade, C-grade and off-grade pulp. The quality classification matrix, with minimum or maximum limits, includes on-line measurements or laboratory tests for brightness, brightness reversion, dryness, dirt count, plastic and rubber contamination, tensile strength, viscosity and pH.
Prime quality pulp production has been increasing steadily since mill startup. In 2006, 98% of production was prime quality. The prime quality production level in March 2007 was 99.3%.
The quality classification is assigned to units and lots, which are then stored in specified "bins" in the warehouse. The DNAstock warehouse management module keeps track of the allocation and movements of quality-classified pulp via bar code readers installed on clamp trucks. The brand of the pulp, either Stora Enso or Aracruz, is also documented.
The pulp is trucked from the mill-site warehouse to the Belmonte marine terminal, which has the capability to store 14,000 tonnes of pulp. Three large barges — essentially floating warehouses — then transport the pulp to the Portocel sea terminal for export. DNAstock is used to manage the movements of pulp between warehouses and then produces truck and barge delivery lists and transfer invoices to Portocel. It also manages and reports on the allocation of damaged or waste pulp.
Management DCS
The combined process and quality information is available every morning (or after working hours) for troubleshooting and daily planning. Fiber line coordinator, Ronaldo Morales Aguilar, and other process area coordinators use process overview displays to identify easily any current process or quality problem so they can set the agenda for the daily meetings. The process coordinators are looking for abnormal process conditions that would affect quality or the production and balance in the line.
Simplicity on the surface, yet depth of information underneath, is the key to the design of the PIMS displays. The graphic displays, configured much like a simplified DCS, allow users to identify a process hang-up in a portion of the line. Then, by clicking on process elements or unit operations more detailed status information and trends about the process can be retrieved from the DCS. There is a lot of information - going back a few minutes, days, weeks or years - just under the surface of the overview display.
"It runs like a management DCS, "says Aguilar. "Every morning we can check the last two shifts. Then with a few mouse clicks you can completely research a problem. We can trace back from the bale lots and track quality variation in real-time. Our learning curve has been assisted by PIMS and our strategies for de-bottlenecking and process improvements have been based on this system," he adds.
The system proved very valuable for the excellent mill startup curve according to Martins. "During the startup-phase the mill staff and all the suppliers needed immediate information. We had meetings twice a day and PIMS was a big help to us," he says.
PIMS's graphically driven process overview displays are configured very much like a DCS — only much simpler. This display covers the complete process from the digester to the warehouse.
Operators' black book
The experienced process operators, who were recruited from other large pulp mills in Brazil, are enthusiastic users of PIMS. An information system display is located in each cluster of DCS video screens for different process areas. When upsets occur, Aguilar says he sometimes get calls at home from the operators. With the portability of PIMS displays, he can open up a process page on his home computer and help them to solve a problem.
Operators make extensive use of the DNAdiary exception reporting function of the system. Process upsets and exceptions are reported and operator comments are added to the incident report. Operators report on lost production and the reasons for it, creating an "operators' black book" for refining working procedures, explains Aguilar. Emails, figures, trends and links can be added to the file. Electrical and instrumentation service technicians at Veracel use the diary function extensively to document service incidents for valves and process instrumentation. Recently, there were 129 named users of the diary function. And, it is used very frequently; over 40 entries per day have been recorded.
The system extends exception reporting one step further by calculating lost production caused by upsets in specific process areas. Pareto analysis charts provide mill staff with an overview of the key areas where production time (and tonnage) losses are most frequent and severe. These lost production reports are used extensively. In addition, the mill has implemented SPC charting procedures within the system for quality management and for tracking key operational indicators.
The DNAdiary function allows operators and process coordinators to enter the reasons for disturbances and lost production
Continuing development
Information management tools such as PIMS tend to be open ended; there are always new reports or data management tools to implement as knowledge of the process grows. After two years of support from Metso Automation, Veracel has now taken over responsibility for application development itself.
According to Guilherme Antonio Tedeschi de Araujo, the need for PIMS will not lessen over time. "We use the system to have better control over mill deviations and corrections. It is the basis for all mill management," he says.
Mark Williamson is a journalist/engineer based in Thornhill, Ontario, Canada.
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