The Santa Maria paper mill in Brazil is carrying through with a multiyear strategy to increase the level of automation, quality control and information accessibility on its two paper machines. The phased plan included the installation of a PaperIQ system on PM1 in 2001and the most recent installation of a PaperIQ Plus system with CD profilers and controls on PM2 in 2006. These two QCS systems with their integral DNAhistorian information applications have turned the productivity of the paper machines around and have improved the paper quality to a very competitive level.
We always hear about the success stories of modern “world class” paper machines which have been built to produce massive volumes of paper for global markets. Without any doubt these machines set the standard for productivity, efficiency and quality. That’s to be expected. But there is another important tier of papermaking capacity which serves local or specialized markets. Many of these mills have paper machines that have been built to the more modest specifications of previous decades – in many cases less than 4 meters width with correspond- ingly lower production rates. But lower capacity mills are faced with the same important issues common to all papermakers – keeping the costs low, the productivity high and the paper quality competitive. Productivity, cost and quality improvement projects on these smaller machines get less press coverage but they are nevertheless very important for the market success and profitability of the paper companies who run them.
Santa Maria Cia. de Papel e Celulose in Guarapuava, Brazil is a case in point. The mill’s two paper machines are by no means ancient in papermaking terms; the 2.5 meter trim PM1 was built in 1975 and the 3.5 meter trim PM2 was built in 1983. Brazil is the main market for their products. Over the years, the mill has invested in machinery upgrades to produce new paper grades.
In the early 2000s, Santa Maria realized that they had to keep control of the costs and boost the productivity of these machines. They reasoned that better, more complete automation and operator information tools were important ingredients needed to accomplish these goals. They implemented a multi-year plan to increase the level of automation, quality control and information accessibility on both machines, while keeping within the budget constraints of a smaller capacity mill. The phased plan, which continues today, included the installation of a PaperIQ system on PM1 in 2001 and the most recent installation of a PaperIQ Plus system on PM2 in 2006. These two QCS systems, with their integral DNAhistorian information applications, have turned the productivity of these machines around and have improved the paper quality to a very competitive level.
Decrease costs, Increase production
Luiz Tadeu Perussolo, Paper Division Industrial Manager, says that, before the new automation systems were installed, operators of PM1 were out of touch with the papermaking process because of a lack of good information about product quality and the variations within the process. “The machine was unstable. Each operator had different ways to operate the machine. This caused variations in quality,” he says.
This instability was also affecting productivity and production cost. “We had many web breaks and high operating costs. Our owners said we must decrease the costs and increase the level of production,” adds Tadeu. Combined with the need for better quality, these directives pointed to a higher level of automation. The mill considered several vendors and, in the evaluation process, visited a very positive Metso Automation PaperIQ reference in Brazil.
The mill purchased first a PaperIQ system for PM1 to standardize the operation and solve the stability problems. The multi-grade machine makes offset paper, machine glazed paper and bleached kraft paper. Grammages range from 50 to 240 gsm. The top machine speed is 400 m/min.
Many things became clear
In addition to the scanning quality measurements, the process information provided by the system’s DNA historian application was seen as an essential ingredient in the mill’s plan to open up the papermaking process to the operators. The system comprised 1000 I/O points including the stock preparation system. “We supplied the information to the operators to help them to make decisions and operate the paper machine in a better way,” says Tadeu. “Once the IQScanner was installed many things (about the machine operation) became clear to the operators. Operators realized some variations were impossible to control. Then, we needed to take actions to solve the process problems we could now see,“ he adds. After these process improvements were made themill began to reap the benefits of the improved process visibility and automated controls. After startup of the new system quality tests were 50% better than before says Tadeu. Web breaks were reduced dramatically, from more than 8 per day to 1 or 2 per day. Average production rose from 65 to 73 tons per day. Today, average production is at 87 tons per day & the record is 112 tons per day.
Customers notice the difference
Tadeu reports many other benefits on PM1 and in customer’s converting plants. He says, with better stability, the ash content of the paper has been raised and strength and optical properties have been optimized. “In the sheeting process the paper is more stable. Customers notice the difference. Also, caliper measurement helped us to achieve more consistent quality,” he states.
As the next step of the multi-year plan, the PM1 system will be upgraded to include CD control.
Impressive results on PM
PM2 was the next candidate for an automation upgrade. The machine makes offset and bond papers with grammage from 50 to 90 gsm. The maximum machine speed is 800 m/min.
The situation on PM2 was quite similar to PM1; the operators had minimal indication of product quality or information about the papermaking process. The existing scanner was unreliable so they needed trustworthy online measurements as starting point. They knew that the PaperIQ system on PM1 had proven its reliability. So the mill started another evaluation process for a new QCS and process information system. The evaluation led to another order for Metso Automation.
The new PaperIQ Plus system and Metso DNA-based information system also includes a first for the mill – cross direction controls. CD grammage control is accomplished via IQSlice control on the headbox and CD moisture control via IQSteamPro located on the suction pickup roll.
The papermaking results after the installation in September 2006 have been impressive. CD grammage variation has been reduced by 35% on the average and CD moisture variation has been reduced by 50%. Moreover, the IQSteamPro on the pickup roll has improved sheet dryness after the third press from between 46 and 47 % to the present 49%. This saves specific drying energy and allows for extra speed potential. Tadeu reports specific steam consumption has been reduced from 2.5 tons of steam per ton of paper to about 2.4 or 2.3.
The extra sheet dryness into the dryer section has also improved machine direction moisture control. Before the steam profiler installation the last dryer section was run with the steam valve running at 100% opening; thus moisture was controlled poorly. Now, with a 60% average steam valve opening, machine direction moisture control at the machine reel is optimized.
PM2 runnability has improved as well. Breaks per day have been reduced from 3 or 4 to the current level of 2 or 3 breaks per day. Overall production rates have increased by about 10%. Machine speed is up 50 m/min on the average.
The mill uses a Maximum Sustainability Rate (MSR) index to evaluate how production rates are maintained at a consistently high value. The index, which compares average actual production to a maximum sustainable rate, has increased from 83% to 85% after the system installation. This index implies a high degree of production rate stability.
Improved quality = better market position
Quality has also improved substantially. With betterCDprofiles operators can run at a higher moisture level without dealing with streaking problems. The increase in reel moisture is around 0.5% percent. Tadeu says low moisture causes static electricity and dimensional stability problems; hence the higher moisture levels avoid these issues.
The improved paper stability has been noticed by Santa Maria’s customers, says Tadeu. “Our customers are very happy because our profiles are better. In our mill the quality rejects related to wrinkles and ridges in jumbo reels have been reduced by 1.6%.”
All told, the installation of the PaperIQ and PaperIQ Plus systems at Santa Maria has been a major factor in improving the mill’s productivity, manufacturing costs and quality positioning. Tadeu sums up the important points about the mill’s focus on improving automation and process information: “The automation systems are valuable tools to keep our position in the paper market with bigger (competitive) companies. And it is important to keep our costs as low as possible by improving manufacturing efficiency.”
In the following years, the Santa Maria mill will build on the current successes and continue on their plan to upgrade paper machine automation, quality management and information systems to achieve better quality and productivity.
