Riau Paper stabilizes the wet end with retention and ash controls.

Riau Paper recently added a wet-end monitoring system to help steady the short circulation system. The resulting production has increased.

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Riau Paper is a papermaking operation located on the site of the April Group's Riau Andalan Pulp & Paper (RAPP) complex in Kerinci, Sumatra, Indonesia. The mill is one-hour flying time west from Singapore. It has an annual output of approximately 2 million metric tons/year of hardwood pulp, making it the largest pulp mill in the world.

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The paper mill currently consists of one Valmet paper machine with a yearly capacity of approximately 350,000 metric tons of uncoated wood-free papers. Most of this capacity is marketed under the April PaperOne brand name. The company is now progressing with plans to build a second paper machine. The company ordered the unit in 1998 but delayed it due to the Asian financial crisis. Since the machine hall is ready, installation of the new machine should occur in the next year.

The existing PM 1 has a trim width of 8.65 m and a design speed of 1500 m/min with most output in the 70-80 g/[m.sup.2] range. The furnish is 100% acacia for the top-of-the-line "PaperOne" branded family of products. For other products, the furnish is mixed hardwood with increasingly more pulp based on acacia because plantations in the area of the mill mature at a rapid rate.

Running the paper mill operations at Kerinci is the deputy general manager, Widjaja Jiemy. He is an Indonesian who has worked in the paper business for 19 years. Trained in France and Canada, Widjaja has been working with the Riau Paper team to increase the machine speed to meet rising global demand for April's paper.

ASCENDING THE SPEED CURVE

Widjaja explained the startup curve on the machine. "The speed up of this machine followed orders booked. From the very beginning, this company has had a market-led philosophy. We only make paper according to the orders we have received. We have been gradually raising the output on PM 1. It has gone from 235,000 metric tons in 1999--the first full year of operation--to a target of reaching 350,000 metric tons per annum production rate during 2003."

As the mill started moving PM 1 up the speed curve, some limitations became evident. Mika Viertola, paper technology manager in Metso Paper's engineered rebuilds and improvements unit, previously worked at the mill as startup engineer from 1998 to June 2000. "As we tried to increase speed and efficiency, we realized that there were some inherent technical limitations, he explained. "The machine had been designed and sold in 1995 and started up in 1998. Between 1995 and 1998, there had been many developments in fine paper machine technology. In early 2001, we offered an improvement package to incorporate these newest advances in PM 1 to help raise speed and efficiency."

According to Viertola, the improvement package succeeded very well and paid itself back to the customer only three months after the start up compared with an original estimate of six months. He noted that this is only partly due to the equipment. "The key to success on the Kerinci PM 1 improvement project was that both the customer and the vendor committed to the targets and cooperated to achieve them. That is something that no equipment in the world can replace."

WET-END MONITORING AND CONTROLS

A major part of the improvement package was the new wet-end monitoring and control system installed in late 2001. The kajaani-RMi system from Metso Automation includes three analyzers with one for headbox stock, one in the dilution water/whitewater loop, and one after the machine chest for the thick stock ash content.

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The new kajaani-RMi system replaced an earlier retention monitoring system from another supplier that had been on the machine since startup. Widjaja noted, "Although the earlier equipment had been monitoring retention since 1998, the old system was not giving us exactly what we wanted. So we looked at the RMi and concluded that it was the best alternative since it offered more advanced and refined control possibilities. We were particularly attracted by the possibility to control ash and filler levels. We saw the potential to save money through optimum use of filler while also improving runnability on the machine."

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Jukka Nokelainen, director of the Metso Automation Asia Pacific analyzers group, explained: "The Kerinci PM had been very active since startup with wet-end management and especially retention. It had always been running with on-line measurement, but one thing was missing--effective control. As part of a PM improvement package, Metso Paper suggested the possibility of the RMi to give them effective control. They saw the benefit quite clearly."

After the startup of the system in 2001, the unit has had use for a continuously increasing scope of wet-end solutions. At first, the primary aim was on-line monitoring of ash and white water consistencies. A little later, the machine team started to study some other applications such as flocculation monitoring in the headbox line.

In early 2002, while gathering new information on the short circulation loop, the mill also started to implement three different types of wet-end controls--retention, HB ash, and feed-forward ash controls.

FILLER CONTROL

Richard Turner, instrument engineer, has been working closely with the RMi system. "The wet-end analyzer has worked very well. At first, we used it as a window on the process. Now that we have gone to the control mode also, we have quickly seen the advantages of better retention control. It has been especially beneficial in stabilizing ash during breaks and helps us recover from breaks more rapidly by smoothing out the ash content fluctuations due to broke."

The mill could accomplish the increased speed simultaneous with developing an entirely new furnish based on 100% acacia. The new furnish certainly presented its own challenges to runnability on PM 1. This makes the accomplishment of the machine crew that increased operating speed and output simultaneously even more impressive.

Regarding the Kajaani RMi system, deputy general manager Widjaja Jiemy concludes, "It is clear that the RMi has stabilized the wet end and has been an important tool in helping us bring up the speed on PM 1. The system has been particularly helpful to us as a means for ash/filler control where we have seen an improvement in product quality and in runnability," he said.

"As we have increased production on the machine, we are sure that the RMi system has played a role. I cannot say it is the only reason, since numerous other factors have contributed to the speed up. It has clearly helped us to run faster and keep within the quality specifications. At higher speeds, the margins of error are less, and we have been able to tighten the band with the RMi."

About the author: Hugh O'Brian has been working with the paper industry since 1977, initially in technical roles and then as a journalist covering the worldwide paper business. He has his own company, Aquaview AB based in Sweden, which is focused on technical communications and consulting. He can be reached at [phone] or [e-mail].

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HUGH O'BRIAN, Aquaview AB