Breakthrough technology in papermaking: exciting breakthrough technologies offer papermakers huge benefits, but implementation time is critical.

Editor's note: This article is part of a continuing series of reports from the Forest, Wood, and Paper Industry Technology Summit held in May 2001 in Peachtree City, Georgia, USA. TAPPI, AF&PA, and the U.S. Department of Energy's Office of Industrial Technology sponsored the Technology Summit.

Everyone has experienced a moment of breakthrough--that instance of epiphany or enlightenment that signals a vast improvement over past circumstances; the significant change that distinguishes the old world from the new. For the paper industry, recently identified technologies may offer this type breakthrough.

A group of industry professionals outlined several breakthrough technologies during a Technology Summit special session. The session convened to determine if closure of a few critical gaps could change the industry's cost structure and the deployment of papermaking assets. A skilled and diverse team including suppliers, owners, members with fundamental thinking, and others with practical orientation assembled to address the challenge. Facilitators and notable networking guests also participated.

The team concluded that the vast quantities of water and air required to facilitate fiber bonding, fiber orientation, drying, and evaporation limit current papermaking technologies. These huge quantities drive capital and operating costs. For example, the paper machine itself represents approximately 15%-25% of a US$ 300 million total installed cost. Pumps, pipes, tanks, drives, and other "auxiliary" equipment consume the remainder. This capital intensity has created facilities and cultures where research and development is far too incremental, slow, and oriented toward the process, not the market.

The group examined operating costs using an economic model developed for the Institute of Paper Science and Technology (IPST). The examination included costs for several grades of paper under a range of conditions such as the doubling of energy costs. The group found that fiber, labor, and energy always ranked in the top four operating costs for newsprint, linerboard, and fine paper as Table 1 shows. Fiber reduction and less energy intensive water removal became key areas for discussion.

Conclusions indicated that large incremental improvements would reduce auxiliary equipment or facilitate the cost of removing or handling papermaking fluids. Breakthrough improvements would change the quality or nature of the fluids.

An important step for the papermaking breakthrough team was a brainstorming session with ideas posted on flip charts without allowing negative evaluations. The group appointed a "champion" for each top choice to tune the idea further. The team dropped lower ranking ideas. Two large incremental projects and two breakthrough projects emerged.

Because the champions were constantly searching for improvements, these projects evolved. Successfully completing the large incremental projects would make the breakthrough projects significantly easier or technically more feasible. Readers should consider how this might happen as they progress from one project description to the next.

INCREMENTAL PROJECT 1: FIBROUS FILLERS

Papermakers have used the filler content of paper to lower manufacturing costs and enhance properties such as graphics. Current technology has produced a practical threshold. For many grades, the industry has achieved no significant progress in raising internal filler content for more than ten years.

Laboratory work has indicated the possibility of developing filler with an aspect ratio greater than 3:1 with some surface adhesion properties. The intent of the first incremental project is to accelerate the development of this idea and increase filler content from the 10%-20% range to the 20%-40% range.

The team identified gaps in this area:

* Difficulty to achieve higher filler retention levels

* Negative impact of high filler retention on sheet properties such as strength and bulk

* Unsuitability of current technology to address the opportunities presented

Fillers engineered to behave more like fibers--having an aspect ratio of at least 3:1 with surface adhesion capabilities--will permit better filler retention and reduce the negative impact on sheet strength and paper machine runnability as Figs. 1 and 2 show. This will allow mills to use more of these materials in the sheet to permit greater substitution for the more expensive fiber component. Successful implementation could raise the non-fiber content of paper 50%-100% over current norms and decrease paper manufacturing costs by 20%-30%. The challenge will be to prove that such fillers can deliver this potential while retaining their lower than cellulose cost structure and providing a suitable return on investment to the owners. Benefits include a reduction of the highest cost raw material and the reduction of specific water use per unit of fiber. Mills can also expect lower energy use. (Since the Technology Summit, Agenda 2020 developed such a project and recently received approval for DOE funding.)

[FIGURE 1-2 OMITTED]

INCREMENTAL PROJECT 2: ONE-WAY PRESS

In the papermaking process, the inability of the mechanical dewatering step to provide higher exiting solids results in large energy costs and capital intensity in the subsequent drying step and runnability implications when the wet web undergoes exposure to open draws. Attempts to run at higher wet pressing solids result in negative sheet property consequences including strength loss through crushing, bulk reduction, and felt marking of fine sheet.

The mechanical dewatering (wet pressing) step limits current state-of-the-art papermaking to exiting dryness of 42%-48%. This second incremental project targets the development of a smaller, possibly retrofitted press section with one-way dewatering to avoid rewet through changes in press equipment and felt design. These changes would effect a 40% reduction in drying energy and increased machine throughput.

The gap is the inability to dewater fibrous paper webs beyond approximately 45% dryness. The opportunity gap of 25 percentage points (up to 70% dryness) could yield US$ 0.5 billion/year in energy savings based on an assumed drying cost of US$ 15/ton and a 40% reduction in drying energy.

If mills could maintain sheet solids at the level in mid-nip that some researchers estimate at approximately 70% solids, mills would achieve significant gains in press solids. One crosscutting and overlapping theme is to reengineer the press so that water does not migrate back into the sheet past mid-nip. This is likely to involve development of press equipment and a "one-way" felt. One suggestion is to manufacture the felt with a non-plugging, semi-permeable surface or membrane that would allow the passage of water under increasing pressure but not allow reverse flow under reducing pressure. Another approach is to introduce air into the nip and felt such that the air would compress at mid-nip and would naturally expand upon pressure release. The expanding air would reduce rewetting.

The breakthrough vision achieves mechanical dewatering using a smaller, possibly retrofitted press section resulting in a 40% reduction in drying energy, increased machine throughput, or both. These significant economic gains use a 4% decrease in drying energy or a 4% increase in production (speed) given a 1% increase in sheet solids and no other bottlenecks. In addition, the potential exists for improved bulk and smoothness, increased product strength, and reduced breaks due to higher wet web strength.

Since the Technology Summit, researchers have developed an Agenda 2020 project and received DOE funding. Early results show significant progress.

BREAKTHROUGH PROJECT 1: ONE STEP FORMING AND DRYING

The most modern papermaking equipment technologies--such as the extended nip press--generally involve commodity products. Paper companies are now discovering that business viability becomes enhanced through a greater focus on consumers. A consumer focus requires greater process flexibility and higher level operator skills.

The current state-of-the-art papermaking process requires a large, capital-intensive footprint, uses large quantities of water and energy, and has a design that discourages rapid and efficient grade changes to meet needs for customized value addition. This project will target the development of a smaller footprint and flexible engineered web assembly plant by exploring the potential of pressure-, dry-, and extrusion-forming technologies.

The project team identified several gaps including:

* Creating a suitable and uniform product using significantly higher concentrations of raw materials in the feed to the papermaking process, i.e., minimum 5% but preferably over 30% entry solids, is difficult.

* The traditional papermaking process cannot build a suitable and uniform fibrous web using a one-step forming/pressing/drying process. Emerging technologies such as those used to produce "Earthshell" and EcoLean" products present potential threats.

* Significantly reducing material costs through greater substitution of lower cost fillers and polymers for the more expensive cellulose is difficult.

* The high orientation of current state-of-the-art papermaking technology toward commodity products relegates pursuit of value-addition to older, less cost efficient equipment. Flexible, productive, and modern papermaking of the future must incorporate technologies that reduce unit capital by at least 50% and permit making value-added products at operating costs at least 50% lower than current norms.

Pressure forming, extrusion, or dry-forming technologies have the best potential to create the major process changes required to address these gaps. Note that a sheet of 20%-40% filler pressed to a dryness of 60%-80% is far more amenable to this process than current sheets. Project viability is 8-20 years in the future and will most likely involve consortia with government and industry support and binding.

BREAKTHROUGH PROJECT 2: SIMPLIFIED PAPERMAKING PROCESS

The commodity product orientation of most modern papermaking technologies generally contrasts with a maximum business viability approach using a stronger consumer focus and the resulting need for greater process flexibility. Total installed cost is commonly US$ 200-400 million and is appropriate for high volume commodity grades. The paper machine cost is typically 15%-25% of total installed cost. The remaining 75%-85% indicates the infrastructure required to support the machine.

This project will target the development of a smaller footprint and flexible engineered web assembly plant. One pathway is to extend the results of the one-step forming/drying project into a compact, modular, small-scale process.

The solution would be a compact, modular, self-contained, flexible, small-scale (printing press size) machine with just-in-time manufacturing that has full automation, is closer to the customer, and requires less capital. This project would spin off the results of the one-step forming/drying project. The vision could include stock supply to a fiber extruder, dry forming (more than 30% solids) with fiber dispersion control and ability for fiber bonding, and dry coating. This system would eliminate or significantly reduce the water requirement, reduce energy and labor, and provide a modularly designed paper machine.

A STARTLING CONCLUSION

Session results exceeded everyone's expectations. The participation and contributions of the team members were exceptional. One guest stated that the team's ideas were "out of the box, but achievable." Another said they appeared to be "stepping stones to the future." Special thanks go to Bob Eamer and David White. They developed the "polished, deliverable" write-up of the projects for display on TAPPI and DOE web sites.

The team suggested some smaller and perhaps incremental projects that did not make the "final four." They need investigation. An example is the "WADS Project" at IPST that will improve fundamental understanding of the mechanism of paper adhesion and transfer. Experiments on the web adhesion and drying simulator (WADS) shown in Figure 3 will probably result in dryer can surfaces that run clean and minimize dryer breaks.

After the groups had sufficiently defined the projects, they outlined the probable time to complete them. This produced a startling conclusion of the breakthrough sessions: The time to complete even the most fundamental project was far too long to meet industry needs. The team challenged the project times and found them to be realistic--even optimistic--with no justification to make them shorter.

Project team members presented an overriding conclusion to the entire Technology Summit. The most optimistic innovation cycles of 7-10 years are about 50% longer then the industry needs. Everyone concerned quickly recognized the problem, but nobody had recommendations to improve the cycle time. This problem remains unsolved and lies at the root of what the paper industry must do.

Key participants:

Bob Eamer--Domtar, Inc.

Marc Foulger--GL&V Research Center

John Glomb--Westvaco Corporation (Now MeadWestvaco)

Herbert Holik--Voith

Markku Karlsson--Metso Corporation

Joe LeBlanc--Smurfit-Stone Container

Ben Thorp--Georgia-Pacific Corporation

Mark Watkins--Mead Corporation (Now MeadWestvaco)

Dave White--IPST

Table 1: Operating costs by grade, using IPST economic model.

Grade                    Newsprint               Freesheet

Annual Tonnage            280,000                  30,000
Furnish              50% TMP, 50%, DIP   68% HW, 17% SW, 15% Filler
Energy Impact        $20 bbl   $30 bbl       $20 bbl   $30 bbl
Total Mill              $370      $513          $449      $475
Delivered Cost/Ton
Fiber                    26%       19%           31%       29%
Chemicals                 8%        6%           23%       22%
Energy                   28%       48%            8%       13%
Labor                    12%        9%           14%       13%
Shipping                 11%        8%            9%        8%
Subtotal                 85%       90%           85%       85%

Grade                        Linear

Annual Tonnage               60,000
Furnish              24% HW, 56% SW, 20% OCC
Energy Impact           $20 bbl   $30 bbl
Total Mill                 $280      $295
Delivered Cost/Ton
Fiber                       43%       44%
Chemicals                    8%        7%
Energy                       8%        7%
Labor                       11%       10%
Shipping                    14%       13%
Subtotal                    78%       82%

IN THIS ARTICLE, YOU WILL LEARN:

* Current process limitations that hinder progress of the paper industry.

* Incremental and breakthrough projects offering the most promise.

* Gaps to bridge before papermakers can implement these technologies

ADDITIONAL RESOURCES:

* For Technology Summit information: www.tappi.org/ctosummit.asp

* The U.S. Department of Energy's Office of Industrial Technology's home page: http://www.oit.doe.gov/forest/forest.shtml

About the Author: Benjamin A. Thorp, III is director of pulp & paper engineering for Georgia-Pacific Corp., Atlanta, Georgia, USA. Thorp previously served in manufacturing technology with Chesapeake Corp., process technology and engineering with James River Corp., engineering with BE&K, establishing a joint venture consulting firm with Poyry-BEK, Inc. and research technology and various positions with Huyck Corp. He currently serves as the chairman of the board of trustees for the Paper Industry Management Association (PIMA), and as a member of the independent advisory board of ForestWeb, the Chief Technology Officers Committee of AF&PA, and the research advisory committee for IPST. Thorp was named a TAPPI Fellow in 1986, received the TAPPI Paper & Board Division Leadership Award in 1994, the PIMA Glen T. Renegar Award in 1999, and was named to the PIMA Leadership Council in 2000. Thorp is the holder of six U.S. patents.