Visy opens up Down Under

Visy has caused quite a stir with its new integrated pulp and paper mill at Tumut in Australia. But the industry is waiting to see how Visy's bosses will cope with the company's transition into a pulp producer

by Rob Ryan

In July this year, Australia's Visy Paper started up a new pulp line at its greenfield mill in Tumut, New South Wales. The opening of the integrated plant marks a major step forward for the Australian pulp and paper industry as Tumut is the first new pulp mill to be built in Australia for two decades. As if that is not enough, the mill's owners can also boast global significance with the plant's innovations in process control and automation, as well as important environmental and efficiency improvements.

As a company with a strong background in containerboard, Visy's directors have broken the mold with the Tumut mill. The unit is Visy Paper's first venture into pulp production. Before the $200 million investment in the plant, Visy had six mills operating in Australia and the US. A total of nine machines produced 1.2 million tonnes/yr of mostly waste-based liner. The upstream integration investment in virgin fiber production is an important strategic move by Visy. Tumut gives the company a guaranteed supply of quality virgin fiber, as well as removing the long term threat to quality from the continued recycling of recovered fiber used in waste-based liner.

Tumut wins the day

The Tumut location also stands out as providing the best all-round advantages to a pulp producer. Visy's planners considered a range of sites before choosing the site in southern New South Wales, 420 km southeast of Sydney. The company looked at Bombala, another town in southern New South Wales, as well as the Green Triangle district on the border between the states of South Australia and Victoria, which is home to several plantation projects. But none of these sites offered all the benefits of the Tumut coordinates.

The Tumut mill stands tall and proud against the backdrop of New South Wales

Outside Australia, the company also considered New Zealand as a likely mill location, but later rejected the idea as the majority of New Zealand's wood resources are already owned or earmarked for use by other companies.

The local abundance of wood was one of the main factors which attracted Visy to Tumut. The plant stands close to three major sawmills, which have large residues available for pulping. On top of that, the site is close to major New South Wales State Forests' softwood plantations. Visy's management saw that the trees in the planted area were fast approaching the stage when large thinning and mature log resources would become available.

"In wet terms, the mill will use 60% logs and 40% thinnings and sawmill residues," says Visy's fiber and forestry manager, Kenneth Epp. "The ratio is closer to 50:50 on a dry fiber basis," he adds.

For the pulp logs, most of the planted area is within a 50 km radius of the Tumut mill site. "Visy has a 30 year wood supply contract with New South Wales State Forests," says Robert Waugh, Visy's projects engineer, civil/government issues. The mill's resource security is further guaranteed by special legislation giving access to New South Wales Forests passed by the state parliament in 1998.

Plenty of plus points

On top of a steady local wood source, Visy's management was attracted to Tumut by its plentiful supply of electricity. The site is located near the 132 KV line which runs from Tumut to the nearby regional center of Wagga Wagga. The area is home to three major hydroelectric power stations built during the 1950s and 1960s as part of the Snowy Mountains Hydroelectric Scheme, which was the largest and most well-known infrastructure project ever undertaken in Australia.

In addition to power advantages, the Tumut site is also well situated for transport facilities. The mill stands roughly halfway between Sydney and Melbourne, the two largest cities in Australia. It is only 30 km from the Hume Highway, the main arterial route connecting the two cities where Visy has some corrugating operations.

On the downside, the mill site originally lacked access to a natural gas supply.

But Visy was able to facilitate the installation of the gas reticulation infrastructure with the assistance of a federal government grant.

The Tumut mill's facilities have been built on a site which stretches to 1,100 ha. The mill itself takes up just 35 ha, while the rest of the area has been set aside for a range of agricultural uses to make productive use of mill effluent, as well as creating a pleasant physical environment. For example, a 400 Ml storage dam has been established to store wastewater during the region's colder months. The water is then used for irrigation during hotter spells. Fresh water is also delivered to a 190 Ml dam at the mill through a 14 km long pipeline from the Tumut river.

Separating the wood from the trees

The Visy mill woodyard is operated on a BOO (build, own, operate) basis. The mill requires 800,000 dry tonnes/yr of wood, which is equal to one million wet tonnes, made up of sawmill residues, plantation thinnings and pulp logs. All of the wood used is radiata pine. The woodyard operator is contracted to supply the mill with the above requirements on a unit cost/tonne basis.

The woodyard features two chip storage piles with a total capacity of five to six days of wood requirements. In addition, there is a further log storage area which can hold 8,000-10,000 tonnes. There are 70 truck deliveries/day of wood to the mill and wood is delivered seven days/week.

Chips from the woodyard are conveyed to the chip bin, where they are pre-steamed. They are then cooked in a continuous digester supplied by Kvaerner before making the journey to an inline refiner. The pulp progresses through a two-stage diffuser washer, then moves to the blow tank before it is pumped to the refiners. Next, the raw material passes through screens before it proceeds to the drum washer. This is followed by the screw press which serves as a last washing stage as well. The pulp is then pumped to a high density storage tower.

Employees from around the mill keep a close eye on production in the central control room

Spent liquor from the digester proceeds to the six effect evaporation plant where it is concentrated to 75%. The first Tubel effect features technology designed to eliminate scaling and plugging. This is followed by five falling film evaporation effects.

The black liquor is pumped to a storage tank and then to a mixing tank which feeds the recovery boiler, which can burn up to 670 tonnes/day of black liquor. The unit also burns vent gases, concentrated and diluted gases and soap skimmed from the black liquor.

The fiber line produces 629 tonnes/day of kraft pulp with a Kappa number of 90. It was designed and supplied by Kvaerner on a turnkey contract basis. The vendor was also responsible for the turnkey construction of the recovery boiler and the power boiler.

On top of that, Kvaerner supplied the recausticizing plant and the lime kiln for the project. The recausticizing plant, which has a capacity of 1,543 m3/day of white liquor, features an efficient cassette filter for green liquor filtration and a pressure disc filter for filtering white liquor. The lime kiln incorporates a flash dryer and has a capacity of 117 tonnes/day.

As well as drawing some power from the main network, the mill produces two-thirds of its electricity needs and all of its steam requirements from the recovery boiler and bubbling fluidized bed (BFB) power boiler. The boilers produce a combined 170 tonnes/hr of steam at a temperature of 460°C and 64 bar. The steam drives an Alstom Power turbine generating 20 MW of electricity and is then used as process steam.

From pulp to paper

Despite all appearances, pulp production is not the sole focus of the Tumut mill. Visy started up a new paper machine at the site on May 8 this year. VP 9 (Visy Paper machine #9), which was supplied by Voith Paper, has a wire width of 5.88 m. The unit has a design speed of 1,000 m/min and a capacity of 240,000 tonnes/yr of kraftliner. The machine produces kraftliner in the 80-300 g/m2 basis weight range.

VP 9 incorporates three MasterJet headboxes, including one with ModuleJet dilution water control. The unit delivers a high standard of uniformity in the basis weight cross-direction profile. This is done through variation of the ratio of stock flowing from two headers to the mixing modules across the width of the headbox. The unit independently optimizes fiber orientation through adjustment of the slice blade.

The headbox is followed by a double fourdrinier forming section. The web then proceeds to the Tandem NipcoFlex press section, which features two extended nip presses. The press is designed to deliver a high standard of dryness for high basis weight liner.

After pressing, the web makes its way to the dryer section which features five dryer groups, including four single-tier Unirun dryer groups and one double-tier Unirun group. The dryer hood was installed by ABB Fläkt. Voith Paper's soft nip calender comes next in the production line and applies a pressure of 210 kN/m to the web. The jumbo rolls are then slit and converted into smaller reels. The finished liner reels are moved by an automated conveyor to the 4,000 m2 warehouse.

Between the startup of VP 9 and the pulp line coming on stream in mid-July, the PM was furnished with recovered paper. The unit operated at just 550 m/min during this period. All of the raw material was high quality pre-consumer clippings from Visy's corrugating and box plant operations, which meant the output from the PM was also high in quality.

"We were producing saleable quality liner from the end of the first day of operations," according to Carlo Bigaran, Visy's projects manager, process engineering/control. But recovered paper now makes up just 20% of the fiber used on VP 9 following startup of the new pulp line. In total, the mill is expected to use 50,000 tonnes/yr of recovered paper.

On-site intelligence

With so many departments such as wood-processing, pulping and papermaking to keep track of, mill employees surely have their work cut out. But the Tumut mill has been designed with a view to making ongoing improvements in efficiency. The unit's ABB-supplied control system is the key to monitoring, explains Visy project director, Austin Davey. Operators will make extensive use of monitoring and they will be able to predict and react quickly to changes in variables. This will lead to efficiency improvements, he explains.

For example, if a sensor device at the very beginning of the fiber line detects a high moisture content in the woodchips, operators at later process stages will be able to make necessary steam and chemical input adjustments to create efficiencies.

The mill has been designed to facilitate communication between operators. It has a central control room for operators from each area of the mill, which contains overhead projectors to display and share information from monitors. In addition, operators have been given thorough and broad-based training, so that they understand the impact of changes in one area of the mill on the operations of the rest of the site. On top of that, the mill layout is compact to promote easy access to each part of the site, as well as increasing communication.

The quest for perfection does not end there, though. Visy expects to achieve important improvements in both efficiency and quality at the Tumut mill as a result of the high and demanding performance standards which it has set for suppliers. The higher standards challenged equipment vendors' current technology and knowhow. The result has been to tighten the control limits used to measure quality and other key variables, leading to less waste and better efficiency, explains Davey. "We have pushed suppliers to get maximum results, but they will also benefit from having the Tumut mill as a reference," he adds.

Clean and green

Visy has also pressed suppliers to make important environmental improvements to Tumut's equipment. These efforts and other careful planning measures led fiber line supplier, Kvaerner, to describe the unit as "the cleanest mill in the world". Careful planning included steps to minimize raw water intake, maximize reuse opportunities and reduce effluent. The mill uses only five tonnes of raw water/tonne of liner output, which is low by kraft pulping standards. Of this, the mill discharges 1.5 tonnes - and all of this goes to on-site irrigation. Much of the remainder is reused. For example, whitewater from the PM is used in the fiber line for pulp washing. It then proceeds to the evaporation plant to ensure that any effluent from the mill is free of salt.

In addition, the project has been planned to operate with low chemical use, through technology such as low temperature cooking, filtering and other techniques. There are no organochlorins or toxins discharged from the mill. Effluent from the facility is treated in a two-step process facility which includes an activated sludge stage.

Tumut's new kraftliner PM is running on pulp from the mill's own fiber line

Odor emissions from the fiber line, evaporation plant and recausticizing plant have traditionally been an environmental issue for pulp mills. But the odor problem has been overcome at Tumut by the collection and burning of non-condensable gases in the recovery boiler. "Under normal operations, the mill has been designed to emit no offensive odors beyond the boundary," says Waugh.

Green and efficient energy use is another positive feature of the mill, as much of Tumut's power needs are met through on-site cogeneration and use of biomass fuel (wood waste and bark burnt in the power boiler). Furthermore, the one-third grid component of the mill's power needs is produced through clean hydroelectric generation.

The Tumut mill is also a forest-friendly project. All of the wood used is plantation-grown softwood or sawmill waste. No native or old growth species or forests are used. The unit is a carbon sink, as the existing and future plantations used to supply wood to the mill absorb CO2. Finally, the mill's use of recovered paper saves 50,000 tonnes/yr of the material from ending up as landfill.

Market pulp expansion

Looking at the bigger picture, Tumut may be smaller in scale than recent pulp mill projects in other countries, but Visy's directors have already laid some plans on the table for expanding the site. This would see the installation of a second pulp line and a pulp drying machine. Most of the unbleached kraft pulp output from the second line would be surplus to Visy's requirements and would be mainly earmarked for export.

If the project goes ahead, the mill will need additional plantations and the company needs to look further afield than the present 50 km radius within which most wood is currently sourced, says Epp. As a result, Visy wants to establish 10,000 ha of plantations within a 200 km radius of the mill. The company is on the lookout for a partner to set up and manage the new forest side. In the meantime, New South Wales State Forests has agreed to establish an additional 20,000 ha of plantations to satisfy Tumut's hungry requirements.

Fellow producers need not feel concerned just yet regarding Visy's pulp boost as the company's bosses are giving little away in terms of timing. It remains to be seen whether the management has bitten off more than it can chew by looking ahead to expansion while the paint is still drying on Tumut's walls. But one thing is for sure, Visy has stamped its claim on at least part of the global pulp market.