Hailed as a gutsy move by some and a questionable one by others, the decision to revamp Weyerhaeuser's Kingsport, Tenn., fine papers mill has not been without controversy. Still, there is little question that the $475-million uncoated free-sheet machine, recovery boiler, and bleached hardwood pulp line make Kingsport one of the most technologically advanced facilities in North America. The company also claims that it now has some of the lowest-cost free-sheet capacity in the world, capable of competing with big exporters like Brazil and Indonesia for domestic markets.
In fact, the new paper machine was originally ordered by a competitor in Indonesia, but the order was canceled. Although the decision to upgrade the Kingsport mill was made during Willamette's tenure in early 2000 when free-sheet demand was growing in North America, Weyerhaeuser has strongly supported the initiative since the 2002 merger, maintaining that it positions the company to capture and hold domestic market share.
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"The new machine primarily targets the copy papers market, which was a huge business in North America until the last few years when email and a sluggish economy impacted demand," describes Mike Edwards, Weyerhaeuser's fine paper manufacturing vice president. "As we brought on capacity in Kingsport, we shut down a number of facilities in our system, and although the market has been tough, we've managed to capture market share in the copy papers area. In the last few months as the U.S. dollar has weakened and the economy has improved, we've been running everything flat out to keep up with customers' demand."
A great deal of corporate and community pride surrounds the new paper machine and pulp line. Situated in the middle of downtown Kingsport, a town with 45,000 residents, the mill's sulfur-free process creates virtually no odor. Also, the massive project pumped welcome tax dollars into the state and local economy during the construction phase. Most importantly, the investment ensures a relatively stable future for the 88-year-old mill.
Despite the pride and enthusiasm surrounding the project, which some have described as a rebuild of the mill "from the ground up," many production and technical details regarding the upgrade are shrouded in secrecy, since Weyerhaeuser views such sharing of information as a potential threat to its investment and competitive advantage.
"We believe we have technological advantages and we took risks with regard to the equipment, and we just don't want to give that away because even a 6- to 12- month lead in the application of technology is worth dollars to shareholders," Edwards emphasizes. "We worked out the nuts and bolts of technology that hasn't been tried elsewhere in the world, and we don't want to jeopardize that. We took a risk and it seems to have paid off."
Mill history and markets
The Kingsport mill has been operating in Northeast Tennessee since 1916, first as the Kingsport Pulp Co. and next as the Mead Corp. starting in 1920. According to the current mayor of Kingsport, Jeanette Blazier, the city was founded in the early 20th century as a planned industrial community. It is still home to an Eastman Chemical facility, as well as a glass plant and printing company.
At its peak in the 1970s, the Kingsport facility operated a pulp mill with five paper machines, as well as converting facilities, and employed 1,300 people. As markets waned in the mid-1990s, including those for printing and writing papers, the community became increasingly concerned about the aging facility. "We were so fearful of losing the mill," says Blazier. "The word on the street was that it could close any day."
One reason the mill enjoys such a good relationship with the community is the use of a nearly odor-free pulping chemistry that it has honed over the years. Instead of sulfur, soda pulping processes use sodium hydroxide or caustic soda to cook chips.
New hope arrived for the mill in 1995 when Willamette Industries took ownership and began making modest improvements. Noting that the mill was just a day away from East Coast markets by truck or rail, as well as its close proximity to company converting facilities, Willamette found the facility of strategic value, choosing to embark on a major upgrade in 2000 to bring Kingsport in line with its other low-cost, environmentally sound, and energy-efficient mills.
By purchasing a Metso free-sheet machine for Kingsport that was once destined for Indonesia's Riau mill, along with upgrading pulping and recovery capabilities there, Willamette chose to challenge the Wall Street perspective that pulp and paper capacity should not be expanded in North America. The $475-million investment in Kingsport was based on a proposed reduction in production costs by approximately $200/ton, according to Willamette CEO Duane McDougall, as reported by paperloop.com in April 2000.
"We'll be closing inefficient equipment and reducing labor and operating costs at Kingsport, allowing us to increase our productivity and profitability," said McDougall. "We have heard estimates of production costs in Asia and Brazil. With converting costs and freight to the U.S., their cost advantage to Willamette's uncoated free-sheet system evaporates. In addition, we believe we are more efficient converters of roll stock."
The new uncoated free-sheet machine at Kingsport, Tenn., dubbed K-1, started up just six months after Weyerhaeuser's purchase of Willamette in March 2002. Weyerhaeuser declines to comment on the new machine's current production rate, but since its startup, the company has continued ongoing efforts to shut aging capacity in order to balance supply with demand. This includes two uncoated free-sheet machines at Kingsport (170,000 tpy); two in Johnsonburg, Pa. (-95,000); and uncoated free-sheet machines in Rothschild, Wis. (-32,000), and Longview, Wash. (-90,000).
Despite challenges of the last few years, uncoated free-sheet markets are picking up in North America (see sidebar on p. 35), where all of the Kingsport mill's production is consumed.
Rebuilding from the ground up
For the Kingsport mill modernization, design and engineering were provided by Weyerhaeuser Engineering Services (WES) out of Portland, Ore., and Fort Mill, S.C., with help from its construction management group. Weyerhaeuser committed 15 engineers, designers, and managers from throughout the company to the project team, but at its peak more than 50 employees were involved in overseeing the project.
WES managed subcontracts in areas such as concrete; steel erection and fabrication; piping design, assembly, and installation in the field; mechanical services; and electrical contractors. Up to eight subcontractors were coordinated by the group at any one time during the project.
Weyerhaeuser chose a four-phase approach to the project in order to commission new equipment gradually, to allow employee training in phases, and to shift construction resources by area. The K-1 paper machine started up in August 2002, the recovery boiler started in October 2002, kiln and recausticizing equipment in May 2003, and the bleached pulp mill in August 2003.
In addition to the success of the startups, WES and the mill are particularly proud of the project's excellent safety record, much of which is attributed to meticulous training practices. At its peak, more than 1,800 construction employees supported the modernization effort. The construction team logged 6.2 million work hours without incurring an OSHA lost-time incident and recorded a 0.7 reportable incident rate.
Without demolishing parts of the mill, the only location for the new machine room was just 20 ft from a major city street, requiring traffic to stop when major pieces of equipment were installed. This still occurs when rolls from the new paper machine are removed for re-covering or grinding. However, it was parking for the 1,800 construction workers that proved to be one of the project's most difficult challenges.
"At first, we overran parking areas near the mill, which was a nuisance," describes Bill MacPherson, engineering services manager. "Next, we used a temporary parking space away from the mill and bussed contractors in each day, but an economic evaluation deemed it too expensive to keep them on the clock that long."
The solution? Weyerhaeuser swapped 33 acres of land from a more remote location of the mill near the treatment ponds and the Holston River, as well as another 32 acres of land located in Sullivan Gardens, for eight acres located next to the mill and owned by the city of Kingsport. The eight acres were converted to convenient parking areas, and the swap was supported by the Kingsport Chamber of Commerce, located just down the street.
"The construction phase brought a huge upturn in the sales tax returns, and we are a sales tax-dependent state," says Mayor Blazier. "Also, downsizing in other Kingsport industries had occurred, but we were able to stay afloat as a result of that strong influence from the construction. It was the largest investment in the state of Tennessee that year."
Unique uncoated free-sheet machine
Weyerhaeuser's new K-1 paper machine can produce uncoated free-sheet in a variety of roll sizes, brightnesses, basis weights, and recycle contents. Its sheet is 15% softwood, with the remainder in various combinations of hardwood or recycled content. Precipitated calcium carbonate is also used as filler in amounts dependent on the grade.
The company is reluctant to share a great deal of information about the new paper machine, but paperloop.com and other sources have reported the machine's width at 345 in. with a design capacity of 430,000 tpy. At a length of 580 ft, it features the latest technology from the dry end to the winder, including a SymFlo D dilution control headbox with 152 actuators to distribute stock evenly across the machine for sheet uniformity.
The SpeedFormer MB forming section is "one of the smallest links on the machine," according to John Ashley, manager of paper operations at the Kingsport mill. An OptiPress single-nip shoe press follows, succeeded by seven single-tier drying sections with 37 cans each, a SymSizer size press for applying starch, and two dryer sections. "It's a pretty standard configuration," Ashley says.
That is, until you reach the equipment after the last dryer section, about which Weyerhaeuser reserves comment. Only seven such units exist on uncoated free-sheet machines in the world, with just two in North America.
Next, an OptiReel provides optimized linear load, tension, and torque control at the reel. This equipment is followed by a WinDrum two-drum winder.
ABB supplied an ACS 600 MultiDrive System for the K-1 with a design speed of 4,500 fpm. The system combines AC drives and a cage induction motor.
Startup of the K-1 paper machine occurred two days ahead of schedule in August 2002. "We made good paper from day one, but we had to wait to qualify it as it ran through our sheeters and on copiers," Ashley explains. "It was a very successful startup."
The smooth startup was just a precursor of things to come, and K-1's runnability attests to the sheet's consistency.
"We've gone seven and a half days without a break before, and it's not uncommon for us to run two days without one," Ashley reports. "You must have excellent sheet formation and machine cleanliness to do that. We also have efficiencies in the 90+% range month after month, and this shows we're making a consistent product for the marketplace."
At Weyerhaeuser's Ridgefields sheet plant located a mile from the mill, paper from the K-1 set a world converting record in May 2003. The facility ran 435 tpd for a 31-day stretch on a 10-pocket E.C.H. Will SLK 216 sheeter. Ridgefields later broke another record with the paper by running 511 tons in one day.
Aging recovery boiler retires
For the modernization project, a complete overhaul of the black liquor recovery island was necessary. Installed in 1948, the Kingsport mill's recovery boiler was thought to be the oldest such unit operating in the U.S., so it was retired in October 2002 as a new boiler came on line.
The Kvaerner replacement boiler is a new single-drum sloped bottom unit designed to process 3 million lb/hour of liquor solids per day at 72%. It can produce more than 465,000 lb/hour of steam at 1,250 psig. A four-level air system introduces boiler combustion air.
The smelt dissolving vents were routed into the electrostatic precipitator (ESP) suction, eliminating the multi-stack wet plume effect and removing another emission point source. This also provides moisture at the inlet to enhance particulate collection in the ESP.
The mill's balance of steam demand is supplied by a biomass boiler that burns wood waste fuel and sludge. Installed in 1998 to replace three coal-fired boilers, the unit can produce 300,000 lb/hour of 1,250 psi steam.
Odor-free pulp mill
During the pulp mill design phase, the company's objective was to create an environmentally friendly, high-quality hardwood bleached pulp in a cost-effective manner. To do so, the newest continuous cooking technology was combined with the existing soda-type pulping process, maintaining the odorless aspect.
Although the equipment it uses is the same as that in a kraft pulping and bleaching process, Kingsport's adaptation of the cooking technology is one the industry's first and is thought to be the only one of its kind in North America.
"Most of our equipment looks no different than what you normally see," says Kingsport vice president and mill manager Charlie Floyd, "but the chemistry enables us to be different and better."
Supplied by Andritz, the mill's new hardwood fiberline is sized for 925 a.d. stpd, although Weyerhaeuser won't comment on current production rates. It consists of a continuous digester, screen room with post-screen drum displacement (DD) washing, a three-stage bleach plant with interstage DD washing, and a two-reactor oxygen delignification system with post-oxygen DD washing.
The digester is a single-vessel hydraulic digester with Lo-Solids cooking. According to pulp mill manager Jeff Chamberlin, the process is "similar in terms of cook time" to a kraft process, but "other parameters are quite different." These parameters, says Chamberlin, compensate for the fact that lignin removal is not as aggressive with Kingsport's cooking chemistry.
The cooking system utilizes the second TurboFeed chip-feeding system installed in the world instead of a high-pressure feeder, which can have high initial and maintenance costs. A Diamondback chip bin is used for uniformly pre-steaming the chips, which are metered into the chip tube and blended with circulating liquor returned from the digester.
Pulp from the digester discharges into a blow tank that feeds what Floyd refers to as a "traditional" screen room that consists of a primary knotter close-coupled to three stages of screening and one high-density cleaning stage. Knots and rejects are washed of good fiber in a single knot and rejects washer before removal from the fiberline system. The pulp from the primary screens is thickened in a pre-thickener and washed in a two-stage DD washer before oxygen delignification, which occurs in a two-reactor vessel system with another two-stage DD washer providing post oxygen washing before the bleach plant.
Pulp is pressed in a Metso OptiPress prior to the first stage of the three-stage bleach plant. Weyerhaeuser won't comment on the bleaching sequence, but two single-stage DD washers provide interstage washing, with a final DD Washer discharging to bleached storage.
The pulp mill startup occurred two weeks ahead of schedule in August 2003 and was "uneventful," says Chamberlin, while pulp characteristics were improved.
"The differences between the old mill's and the current mill's pulp is that it's cleaner-around one point brighter," he describes. "It's fairly similar to conventional southern bleached hardwood, despite the cooking chemistry. The pulp line produces a very strong fiber that mixes well with the southern softwood kraft pulp that we receive from other Weyerhaeuser mills."
At the new K-1 paper machine, the results have also been well received.
"The machine has not produced a single ton of off-spec paper that could be attributed to pulp mill quality," says Ashley.
Controlling the new equipment
The Kingsport mill uses an ABB Advant distributed control system (DCS) platform in its three control rooms, one located at the paper machine and the other two in the pulp mill, where the power and recovery room and pulp control room are situated next door to each other. The rooms feature large, flat-screen monitors for displaying various control schemes and camera inspection photos, and the mill's 25 control consoles communicate via 17,400+ I/O points.
"The consolidation of a number of control rooms throughout our modernization project has helped us tremendously in terms of communication between departments and allows us to focus the automation in just three different areas," Floyd explains. "For example, we often compare alkalinity tests between the boiler house and the pulp mill and jointly agree to adjust operating rates."
The control scheme for the paper machine uses both ABB's Advant and Metso Automation's DNA distributed control systems. DNA controls the cross direction, while Advant controls the machine direction. This poses no problem, according to control engineer Rhonda Smith, since both control schemes use a block programming language and can communicate.
The K-1 machine also features a Sensodec web runnability monitor with digital imaging from Metso, as well as an ABB quality control system that includes two Smart Platform scanners for measuring weight, moisture, ash, color, formation, opacity, and brightness.
