Stora Port Hawkesbury hopes to tap into North America's lucrative high-end publication papers market with its new C$750 million PM

by Kelly H Ferguson and Greg Rudder

Stora's new PM strides into North America's SC market

T he startup of Stora Port Hawkesbuy's new PM 2 has seen Swedish paper giant Stora enter the North American magazine and catalog papers market with a bang. The new 350,000 ton/yr machine started up in mid-April and is designed to produce the highest-end supercalendered papers - SC-A and SC-A+. Traditionally these paper grades are used more in European countries, but they have already found favor at some US consumer publishing companies and have the benefit of lighter weights and cost compared with LWC grades.

The C$750 million ($491 million) project included a new thermomechanical pulp (TMP) plant (see box) and has brought new life to the mill and to the Nova Scotia community that surrounds it. Prior to the investment by Stora, there was some concern that the company might pull out, leaving a significant hole in the area's industrial base. But the mill is now a major supplier of newsprint and SC papers, giving Stora a strong presence in the US and Canadian markets.

The mill was started up in 1962 to produce bleached sulfite market pulp. In 1971, a newsprint line, including a groundwood pulp mill, was added. The newsprint line currently produces about 190,000 tons/yr made from a furnish of groundwood and high-yield sulfite pulp. The bleached sulfite market pulp operations were shut down during the construction phase of PM 2.

Stora gave the PM 2 project the go ahead in December 1995. As president and general manager of Stora Port Hawkesbury, Jack Hartery, says, the company saw an opportunity in North America for high-end SC papers and decided to move in that direction.

Project manager - SC project, Anders Backlund, points out that this was designed as a fast-track North American project to try and take advantage of the market growth for SC papers. The project took just 23 months from groundbreaking to startup, and only about 18 months from the time the main supplier contracts were signed.

Inevitably on a project of this scope, a large number of contractors and subcontractors were involved in both design and construction. Andritz Sprout-Bauer teamed up with engineering consultant Klockner Stadler Hurter and construction contractor Kamyr Enterprises (a subsidiary of Ahlstrom Corp.) in an engineer, procure, construct (EPC) project on the TMP plant, while Jaakko Pöyry of Finland handled detailed engineering of the papermaking process.

Groundbreaking at the site was in May 1996 with the first pre-cast concrete columns going up in late July. The TMP plant was commissioned in October 1997 and TMP was being produced and used as a trial in newsprint production by February 1998. The new paper machine was started up on April 15.

Racing for the top

The startup PM 2 not only capped a three-year effort at building one of the most advanced paper machines in the world, it also signaled the next battle in a marketing war to capture the hearts and dollars of publication paper buyers. At stake are millions of magazine and catalog pages that Stora hopes will some day be made from its MagniPress line of uncoated and supercalendered (SC-A) papers.

The machine is the first in North America designed specifically to make the highest of supercalendered grades - SC-A+. And when the machine reaches full capacity, Stora Port Hawkesbury will be the largest SC producer in North America, ahead of Abitibi-Consolidated, Lake Superior Paper Industries, Madison Paper and St. Marys Paper. In fact, the machine will add about 21% capacity to the growing North American SC market.

According to Hartery, when the company began analyzing the market for SC papers, there was a significant amount of high-end SC paper use for magazines in Europe with only a small amount of LWC use. Just the opposite market situation existed in North America, which is traditionally a heavy user of LWC.

"We saw that as an opportunity in North America," Hartery says. "We have a fair amount of LWC capacity within the company and were disproportionately low in supercalendered grades. And supercalendered paper is one of the most dynamic growth markets in North America and Europe."

Stora's sales arm for the project, Stora North America, has been involved in a continual promotional campaign to convince paper buyers in the USA and Canada to switch from coated paper - traditionally the medium of choice in four-color magazines, catalogs, and inserts - to an uncoated grade it says performs comparably. The technology used on the machine, including two supercalenders that are the latest wave in calendering developments, impart a surface that delivers excellent printing properties, the company says, adding that the machine delivers a sheet with brightness and optical properties equal to lightweight coated (LWC) groundwood.

To achieve its goal of gaining market share in the lucrative publication papers market, Stora is counting not only on its technical expertise (Scandinavian papermakers were the first to make SC-A+), but an ability to sell MagniPress at 10% to 15% below the price of No. 5 LWC. That's certainly an issue for publishers, who know that it is only a matter of time before supply-demand driven prices cycle upwards again.

While Stora has made some inroads in securing customers for SC papers, it faces an uphill battle. Quality concerns have been voiced by some and technical glitches have hampered delivery commitments of the SC-A+ grades. Coated papermakers have retaliated against Stora's marketing push with their own highly visible advertising campaigns. And the number of manufacturers with the ability to produce premium SC printing papers is suddenly getting bigger, with several new projects in the works.

Switching over

There is an emerging trend of publishers converting to SC paper from LWC that Stora hopes to build on. A Stora source said the machine already has orders from 58 customers. All the machine's tonnage would be sold in North America. Marketing plans for tonnage from the machine are not expected to be affected by the proposed merger of Stora with Enso.

Roughly 60% of the new machine's tonnage will go to magazine and catalog publishers, including some which have traditionally used higher-quality and higher-priced lightweight coated paper. The other 40% will go to retailers that use SC paper for advertising inserts in newspapers or through direct mail.

The mill plans to make 150,000 to 175,000 tons of SC-A and SC-A+ this year, with hopes of reaching full capacity by 2000. At the start, the company did experience some problems producing SC-A+ paper, but the company has not lowered its estimated output for this year, and the machine will run faster to compensate for lost time. In its first month, PM 2 ran as fast as 1,500 m/min for as long as 60 hours, a source said.

The PM is a world-class unit that contains the best possible technologies for producing SC grades, according to Tor Suther, vice president - SC line. The machine is primarily a Valmet unit with Voith Sulzer supercalenders and Jagenberg winders and rewinder.

"We investigated the technology developments from all suppliers in planning this machine," Suther says. "The reason we went with primarily a Valmet machine is based on our [Stora's] experience. Stora has similar equipment on several machines in Europe. We chose the technology based on our own operating experience and in surveying what other new SC machines throughout the world have used. Most of the technologies have been proven through experience."

The machine is 146 m long, has a wire width of 10.15 m, a trim width of 9.46 m and a design speed of 1,800 m/min. In early June, the machine had already reached a speed of 1,517 m/min, making it the fastest SC machine in North America. The world speed record for an SC machine is 1,625 m/min, held by Norway's Norske Skog mill (Suther's former employer).

The machine is capable of producing SC-A and SC-A+ grades for both offset and rotogravure printing processes. Targeted end uses are magazines, catalogs, and inserts/ flyers. The average basis weight for grades produced on PM 2 is in the range from 40 to 66 g/m. The brightness range is 68% to 72% ISO. Ash content in the sheet is in the range of 20% to 35%.

The paper machine stock preparation system begins with a medium-consistency storage tower with 16 hour capacity. TMP stock is pumped from the storage tower to two Andritz 52/58 TwinFlo post-refiners. Northern softwood kraft, purchased in bale form, is also sent through post-refining using two Andritz 34/36 TwinFlo refiners. Suther says the mill currently uses 15% kraft in the sheet with plans to drop below 10% once the machine is through its startup curve.

TMP and kraft pulps are pumped to a mixing tank where the majority of clay filler (supplied by ECC International) is added, along with broke and recovered fiber from two Alfa Laval Celleco disc filters. From the mixing tank the stock is sent to the machine tank, to the wire pit, and then to the Ahlstrom first-stage pump (where the remainder of the filler is added). From the first-stage pump, stock is sent to what Suther calls "the world's biggest deaerator", supplied by Ahlstrom. Stock is then screened using two Valmet 0.3 mm slotted machine screens running in parallel before being sent to the headbox. Other chemicals added include retention aids, defoamers and wax if the mill is producing offset grades.

On form

The forming section of PM 2 is a vertical Speed-Former HS gap former using a SymFlo D dilution control headbox with flow tubes spaced at 60 mm intervals across the former. Suther comments that the dilution control headbox, still a relatively new concept for SC grades, provides excellent profiles. The mill uses several fabric suppliers for the forming section, including Tamfelt, Martell Catala and Albany International. Sulzer Turbo supplied the PM's vacuum system.

The press section is a tri-nip press that begins with a pickup press, has a shoe press in the third position and has a separate fourth press. Suther says this is the first application of a shoe press for SC grades. "We believe that the shoe press can give us more even profiles, which means improved runnability of the machine," he says. "We have gone, at maximum, three days without web breaks, and I believe the shoe press is one of the reasons. It is giving us good moisture profiles, it's easy to get the paper through the press and we're getting good sheet dryness coming into the dryer section."

"Since no one has experience running a shoe press on these grades, we are continuing to investigate the best way to run it," Suther says. "It can press up to 1,000 pli (175 kN/m), and we've been up to 750 pli (131 kN/m), but we're still experimenting to find the best operating parameters."

Also included in the press section design is a space to install another shoe press in the first press position. Fabrics for this section are supplied by Geshmay and Scapa. Double doctors are used on the center press roll and the fourth press roll.

Drying up

The dryer section is a single-tier design with nine dryer groups and a total of 45 drying cylinders. Suther says Port Hawkesbury is the first SC-A+ machine in the world to use this particular single-tier configuration, where all dryer cylinders are on the top row and all vacuum rolls are on the bottom row. Fabrics are supplied by Albany International and Scapa. Suther adds that one of the biggest benefits to the single-tier design is that when a web break occurs, the sheet goes straight to the basement where a fabric conveys the broke to a repulper.

Following the dryer section is a Honewell-Measurex hole detection system, a quality control system (QCS) scanner from Valmet Automation, a sheet remoisturizer from VIB and another QCS scanner. The scanners measure basis weight and moisture. The machine reel is an OptiReel unit using center-driven reeling and automatic reel change features so that operators can remain in the control room and change the reels.

Parent reels are transported via rails to one of two 1,500 m/min, 10-nip Voith Sulzer supercalenders that utilize the Janus concept. This technology uses high-temperature steel rolls and synthetic covered rolls, alternately stacked, to allow high-pressure, high-speed calendering. Other features include Voith's NipCorect rolls for CD caliper control and multiple-zone Microflow steam boxes for added quality improvement. Both calenders are equipped with flying splice and a Sensomat-Plus rewinding system. The calenders also feature center drive reeling, as well as automatic gloss control. According to Suther, "We're the first to use these calenders on SC-A+ grades and the decision to go with this technology was based on extensive trials."

After each calender is another hole detection unit, a QCS scanner and an automatic reel upwind station. Reels are lifted by overhead crane from the upwind stations in the basement to the winder area. The mill uses two 2,500 m/min Jagenberg Vari-Top single-drum winders that include automatic features such as reel change, set change, automatic gluing of the core and automatic knife adjustment. The winders can produce rolls with a maximum width of 3.8 m and diameter of 1.5 m.

Hole detection information feeds forward to the winder and rolls that have holes are removed and sent to a separate Jagenberg Vari-Top rewinder so that the holes can be cut out. Rolls are then conveyed to a Saimatec automatic robotic wrapping line that has a capacity of 2,550 rolls per day at a cycle time of 27 seconds. Automatic features include roll marking, head application, wrapping, crimping and labeling.

In addition to an advanced automated winder operation, the mill also invested in an automated core preparation, handling and delivery system supplied by Core Link. The system begins with a programmable pickup robot for transferring parent cores (3" to 6" inner diameter) from storage racks to the cutting station. After automatic cutting, the system also has stations for reaming (inner diameter and outer diameter), notching and capping. Fully prepared cores are discharged onto a conveying system for transport in set sequence to the winder and on a just-in-time basis.

Controlling the mill

A Valmet Automation Damatic XDi DCS provides controls for the stock prep area, machine flow controls and paper machine logic. Drives for the machine are variable speed AC units supplied by Siemens. In addition to the machine level automation, the mill utilizes several layers of information systems, including a Windows NT-based production management and tracking system from Elsag Bailey (Canada), a Marcam Solutions asset management package and an OSI Plant Information (PI) millwide information/ data historian system.

The new TMP plant gives Port Hawkesbury ideal pulp properties

The primary fiber source for the mill is a mixture of spruce and balsam fir, with about a 7% maximum of other species. Woodchips are kept in two 10,000 m chip storage silos and conveyed to a 250 m Kone atmospheric pre-steaming bin. After discharge, the chips are taken to the washing system, which includes an Andritz Sprout-Bauer chip washer/trash separator. The rotary chip washer discharges the chips and washwater where they are taken to a twin-screw chip drainer.

Washed and drained chips go to a 50 m pre-steaming bin with a 25-min retention time, where chips are heated with clean low-pressure steam. A vibrating-bottom discharger smoothes the flow of chips onto the feed table going to the Andritz MSD Impressafiner. The Impressafiner is a multiple-screw device where the feed end squeezes water and water-soluble materials from the steamed chips.

RTS refining

Each of the TMP plant's refining lines has capacity of 500 tons/day, which MacKenzie acknowledges is oversized compared with the rest of the plant. For normal operation, the mill only runs at about 385 tons/day for each line. The system is Andritz's RTS (retention-time-speed) process. "What RTS gives us is, first, energy savings," he says. "Second, with a short time in the high-temperature, high-pressure zone, it gives us better bleachability and brightness. You don't get the darkening of fibers because of the dwell time within the system. In terms of strength, we're getting the fiber strength that you would get from a standard TMP process, but we don't do it with such a long retention time. We've noticed that when we run this system at reduced pressures compared with the higher RTS pressures, we don't get as strong a pulp."

The primary refiners are the world's largest single-stage refiners. The Andritz Sprout-Bauer Twin 66 units are driven by 26 MW synchronous motors through speed increasing gearboxes. The refiners operate at 2,300 rpm, but can be upgraded. The secondary refiners are Twin 66 units directly coupled to 23.9 MW synchronous motors. Secondary refined stock and the balance of the refiner-generated steam are similarly blown into a pressurized cyclone for separation. Pulp leaving the pressurized cyclone is fed to the low intensity tertiary refiners - SB-150 units. From here, pulp from both lines is pumped to the latency tower, which has a minimum retention time of 45 mins.

Screening, fractionating, cleaning

Refined stock is pumped through two Valmet screening lines where accepts are fed forward to be centrifugally cleaned and thickened. Secondary screen accepts are sent forward with the primary screen accepts, which go through a six-stage fractionating and cleaning plant using equipment from Noss and Andritz.

Rejects from the screening and cleaning systems are collected in the unrefined rejects chest, and pumped to two four-screen reject dewatering presses. Controls ensure that maximum discharge consistency (30% to 32%) is maintained, which helps to maximize fiber strength properties in the following two high-consistency reject refiners.

In the reject system, there is only one line of screening. Screen accepts are fed forward to the fractionating plant along with the mainline screen accepts, while rejects are fed to the rejects secondary screen.

Pulp bleaching

From the cleaning section, medium consistency stock is pumped to an unbleached pulp silo. It has a three-hour retention time to provide a buffer between the refining lines and the bleach plant. Bleaching is carried out at high consistency in a tower designed for a maximum retention time of three hours. However, the mill only uses between 90 minutes to two hours. As MacKenzie says, "We've found that it is not necessary to leave it any longer and risk darkening of the pulp."

Bleached pulp passes through a transfer conveyor and rotorlift into a dilution conveyor, where a combination of freshwater and paper machine whitewater is added, and pulp consistency is reduced to approximately 12%. The diluted pulp drops into a standpipe feeding one of two MC pumps. The MC pumps transfer the bleached pulp to a second set of TWPs for washing.

Thickened pulp exiting the TWPs (at about 35%) is diluted, sourced with SO2 water, and pumped via an MC pump to the MC storage tower, where the pulp is stored at about 8% to 10%.

The TMP process is controlled using a Valmet Automation Damatic XDi distributed control system (DCS) with a Pulp Expert fiber analyzer for automatic pulp sample analysis to measure such properties as freeness, fiber distribution and brightness.