 Actually, the issue should be stated, "Will these paper machine designs as we know them today, survive in the future?" While some may later conclude this discussion borders on fiction or is based on conjecture, hopefully a few thought-provoking "truisms" will be recognized. It will be noted that other paper grades, such as tissue/towel and board have not been included since these remain in demand in their current markets.
Of course, the types of paper machine designs vary widely, and at any given time, there is a difference in both age and efficiency. Although different designs are used to manufacture the specific grades, the basic layout has remained the same for many years. And all suffer from an inherent lack of flexibility when a machine has to be modified to manufacture a different grade. Even what appears to be a simple change from fine paper to pulp production can result in complex design related issues.
It is recognized that demand for the above grades has decreased, related to the rapid rise in digital media. During the same period, manufacturing costs have increased due to higher energy and environmental costs, even with the higher use of recycle fibers. Newsprint and Publication paper market products depend heavily on advertising to remain viable. Overall, advertising continues to increase at a projected 6% annual growth rate over the next five years. This may seem to be encouraging until one realizes that the growth rate in Newsprint, magazines, and books recently has been only 2.0-3.5%, compared to digital media advertising growth of 20-40% in a the same time period (2008-2012). Digital media advertising has grown so strongly, the market share currently is estimated to be above 38%, and may actually overtake TV advertising by 2017, if the current trend continues.
It is also apparent that fine paper usage has been declining due to laptop computers and electronic tablets steadily replacing writing paper in the school classrooms. The U.S. Department of Education estimates at least 66% of teachers use computers for classroom instruction, and that 99% of schools have computers available. It is further claimed that 98% accessibility to the Internet exists somewhere in the school buildings. If the need to teach cursory writing is eliminated in the future, another need for paper may be eliminated. Due to the interactive ability and wide subject content provided by computers, teachers are convinced student learning is being enhanced. Paper equipment manufacturers have already concluded that the best opportunity for traditional media at this time is in China, India, and other developing countries. But even those countries may experience a rapid change to electronic media in order to remain competitive globally.
To continue this discussion, two assumptions are made: 1.) There will continue to be a future demand for the above paper grades, although usage may continue to decline, and 2.) The current Newsprint, Publication and Fine paper machine designs cannot survive in the longer term. This is not meant to be critical of current paper machine manufacturers and designers, since they have done an outstanding job of creating high production rate machines operating with high efficiencies. It is simply an opinion that consideration must be given to significantly modifying or changing the machines used for these paper grades as demand continues to decline.
A few of the macro issues threatening the long term viability of the subject paper machines, other than the previously discussed digital media form of communication, are as follows:
• They occupy too much space and require too much equipment. The basic technology for paper manufacturing, which consists of a head box, forming, pressing, drying, machine calendaring and winding has existed for many years. Depending on the grade, other steps may be included, such as sizing, coating, and super calendaring. The drying section alone can take up 60% of the total paper machine length.
• They require entirely too much water. Notice that requiring significant amounts of water is not the same as consuming the water. Paper machines make extensive use of recycled water and care is taken to assure effluents meet environmental requirements. But, water is becoming an increasingly scarce and often protected resource. Diluting fiber to 0.4% consistency only to subsequently dry the web to 5-6% moisture content is a luxury that future machines may not be able to afford.
• They consume too much energy, and energy costs will continue to increase. Using a large number of steam cylinders to dry paper is problematic in terms of energy cost. Bear in mind that the drying section consumes up to 78% of the total cost of dewatering the web. It also contains complex and often misunderstood steam condensate systems.
• They are not production efficient outside their design speed range. This is one of the reasons mills for many years continued to use older design machines to produce paper for smaller orders.
What if the production of paper for our discussed grades has to be manufactured in smaller quantities in the future, analogous to the printing on demand done by many publishers today? Will smaller conventional paper machines be built, or will different technologies be further developed to meet the new market demands? I believe an entirely different paper machine concept will need to eventually evolve in order to survive economically. Here is one possible scenario for consideration:
• The paper web should be formed from higher consistency stock. Another possibility is complete dry forming, a technology that has already been done commercially for grades such as toweling/wiping. It would need to be modified significantly to manufacture paper type grades, and likely require combining multiple layers.
• With a higher consistency web, a single nip wet press section might be used for required densification. This could involve a single hot press or the use of displacement pressing technology.
• The size press would be eliminated, with desired web properties being obtained earlier in the manufacturing stages.
• The drying section would be significantly reduced in the number of drying cylinders and also in length. More likely, steam cylinders could be eliminated and the additional drying accomplished by infra-red or hot air techniques.
• A single nip calendar would be used for final caliper and density control.
• If the web requires a coated surface, coating would be done off-line.
• Any additional finishing required would be done using a single nip calendar with composite roll covers.
• All grade changes would be completely computer controlled. Short start-up and shut down times become a necessity, linked to a "just in time" manufacturing approach.
The writer encourages further development of the dry forming concept for the future, since this involves no waste water or effluent gases. Internal sheet strength could be controlled by using special binders, perhaps cured using thru-air or infra-red energy. Finishing could be done by composite roll calendars, and ideally a sheet could be produced which would require no further surface coating.
Regardless of which technology evolves, the future paper machines manufacturing the subject grades will need to be smaller in size, more energy efficient, capable of rapid start-up/shutdowns, and responsive to on-demand manufacturing orders.
Robert Moore is a retired chemical engineer, and is an experienced technical and fictional writer. His past work experience spanned the chemical, paper and equipment manufacturing industries, including holding management positions at Voith Paper, Scapa plc, and The Mead Paper Corporation. |
