The Brazilian milll rebuilt its board machine on a shoestring budget, but now it is seeing the benefits
May 2007
By Graeme Rodden, Editorial Director, Magazines
Innovative thinking helped Embu mill pull back from the precipice of closure. Built in 1951 as a newsprint mill, the facility's cylinder board machine (BM 3) was installed in 1976 but had seen little work done to it since startup. (The mill has long since given up newsprint production).
The Embu mill, situated near Sao Paulo in Brazil, was reaching a crisis point. The one-machine mill, averaging 130 tonnes/day of folding boxboard (220-330 g/m2), had to modernize or close, but with money tight, the options were limited.
With a new machine out of the question, then owner, Ripasa (see below) decided on a rebuild, opting for Metso Paper's Val technology. The first objective of the rebuild was to improve quality. This was a must, according to mill superintendent Jarbas Marques Ribeiro. "We had no bulk or stiffness. Our quality was not good," he states flatly. "With the rebuild, we've had some very interesting results with the quality of production. Our learning curve was very fast. There were no startup problems. We had better than hoped for results: record production three-to-four months after startup. We've reached our runnability, smoothness and stiffness targets."
The mill shut down the machine in January 2006 and started up again the following month (February 10). The first reels came off BM a day later. In all, it took 25 days, paper to paper, as budgeted. In late 2006, Ribeiro estimated the mill to be seven months ahead its expected learning curve.
The total cost of the rebuild was $15 million and was done in two phases: first the machine and then the quality control system (QCS) that was installed in August 2006.
For BM 3, Metso installed three fourdriniers and ValFlo headboxes, rebuilt the press section and installed two new dryer cylinders as well as a ValCoat coating station. Siemens supplied new drives for the entire machine. The machine was pre-assembled in Metso's Sorocaba, Brazil, workshop, prior to being shipped to Embu.
The new headboxes are simpler to operate and easier to maintain than the old ones that had rectifier rolls. Profile variations have been minimized because of the new control, which also allows more flexible adjustments to CD profiles. One of the great benefits of the new equipment is the huge improvement in formation.
Because of the increased speed and capacity of the machine, the stock preparation handling and approach systems had to be modernized. Two of the three stock prep systems were updated; one was replaced; three new approach lines were installed.
Better quality opens new markets
The new design speed is 350 m/min and production has jumped to an average of 185 tonnes/day (depending on the basis weight). Trim width is 2.55 m. The basis weight range is now 150-400 g/m2, but Ribeiro explains that 250 g/m2 is the most popular grade. The optimum weight, in terms of speed, quality, formation and production, runs between 250 and 270 g/m2.
The mill's product lines ranges from solid bleached sulfate board (SBS), to triplex and duplex grades, to special boards with barriers. Ribeiro notes that the mill can now make board with a high bulk, which was one of the main aims of the project. It also means that Embu can produce lower basis weight board that has the equivalent stiffness of heavier weight board. Virtually every quality parameter has been improved at Embu, allowing the mill to focus on new markets.
The ValCoat coating station produces board with good gloss and a smooth surface. This provides an excellent printing surface. The ValCoat replaced an air knife coating system. A misting problem has disappeared thanks to the new technology. Perhaps more importantly, energy savings have also been realized since drying has improved.
Another energy saving was achieved when a natural gas pipeline from Bolivia was completed, allowing the mill to switch from oil. Water consumption has also fallen, from 13 m3/tonne to 10 m3/tonne.
Embu's furnish is a mixture of recovered paper and virgin pulp. It uses bleached kraft pulp from Ripasa's Limeira mill as well as groundwood pulp, TMP and CTMP and waste paper (overall, about 15% OCC is used in the furnish). As part of the project, the mill installed a new recovered paper handling system.
The 30% increase in production was helped immeasurably by the debottlenecking in the recovered paper handling system.
The QCS is a PaperIQ system that is light years ahead of anything the operators had worked with before. In fact, previously, the operators had no tools to control quality parameters. These were controlled manually. Now, as Ribeiro notes, there is much more precise control of moisture and caliper.
Since it was a total change, there was some fear among the operators. However, an intensive training program (in-house and with Metso) soon put these fears to rest. "There was a lot of training and the crews adapted to the new technology with ease," says Ribeiro.
The rebuild focused on the board machine, not the finishing end. If all continues to go well -- the mill is running flat out -- there is a good chance Embu will look at a project to improve this area in late 2007. A few more months should not be that long a wait. After all, as Ribeiro says, "We had been working on this rebuild since 1985."
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Between commissioning Metso to upgrade the board machine at Embu and the completion of the work, Ripasa was jointly taken over by fellow Brazilian pulp and paper producers, Suzano and VCP (2005). Last October, VCP announced it wished to sell its 50% stake in Ripasa to Suzano, a deal that was duly completed at the end of March 2007. Suzano paid VCP $20 million to take 100% ownership of Embu.
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