Mills pursue cost effective performance chemistry.
How can performance chemicals (any chemical that imparts a special benefit to the user) contribute to this process? To find out, Solutions! interviewed selected performance chemical experts, who offered several strategies.
According to Kasy King, principal of Papermaking Process Consulting LLC, Appleton, Wisconsin, USA, the word "how" in this question may be taken two different ways. "If 'how' refers to the process, then there is one direction to take; if 'how' refers to the mechanics, there is another direction," said King. "For the process path, all specialty chemicals should be used only if the value to operations exceeds the cost of the chemical. It does not seem likely that operations would use any additive that costs more than it returns."
The value of any chemical is a combination of measurable parameters that might include its cost, benefit, and how it is serviced. For example, value is measured by a reduction in the cost of other additives; a clean, deposit-free machine that runs longer; or a service package that helps solve problems, said King.
"One should not implement a specialty chemical without first determining how the value of that additive will be measured," he said. "The mechanics of the 'how' means that operations should focus on the storage, make down, and feed of the chemical involved. Doing any of these three tasks incorrectly or improperly runs the risk of eliminating or minimizing the value attributed to the additive."
According to Irenee Philippe, director of technology, Ciba Specialty Chemicals, Suffolk, Virginia, competitive advantage is achieved when performance chemical programs allow newer machines to optimize their operating windows with maximum return on investment (ROI) while enabling older paper machines to operate more competitively without major capital investment.
"To reach an acceptable ROI, the chemical program should deliver benchmark improvements in machine speed, quality, runnability, and reduced energy consumption," he said.
Performance chemicals enable paper producers to change the process by which they manufacture paper and deliver desirable sheet properties, according to Brine Ranson, global printing and writing market segment manager, Hercules Paper Technologies, Jacksonville, Florida. "Typically, the benefits fall into two broad categories: machine productivity and sheet end-use properties," he said. "Performance chemicals enhance machine productivity, allowing papermakers to move beyond existing mechanical system limitations. These applications not only enable the papermaker to produce more saleable tons per day by addressing process bottlenecks or limitations, they also help the mill meet regulatory and environmental goals without additional physical unit operations."
Ranson also pointed out that performance chemicals allow papermakers to deliver sheets with end-use performances beyond what is possible when using filler and fiber combinations alone. Some sheet properties can be developed with mechanical operations; but performance chemicals allow the papermaker to develop new grades, manage production growth curves, and respond quickly to changing market demands without making capital investments, he said.
"These applications deliver measurable performance properties that increase the paper's inherent value to the end user and help differentiate it in the marketplace without the cost and delay of mechanical installations," Ranson concluded.
Greg Bengtson, director of marketing and supply chain management for Eka Chemicals, Marietta, Georgia, noted that some performance chemicals can benefit a broad cross section of paper grades. "Silica nanoparticle technology systems and anionic trash collectors (ATCs) improve productivity and properties across all grades," he said. "Advanced retention, dewatering and strength aids--especially when designed to work in synergy--help achieve improved sheet properties that lead to smoother coating, converting, and printing. They add value at every step."
Chris Smith, global program manager, mechanical grades, Nalco Co., Naperville, Illinois, said that specialty performance chemicals provide value in the papermaking process by improving both operational efficiency and imparting certain physical properties to the finished sheet.
"Using these tools to deliver such results in a cost effective manner requires a comprehensive understanding of several critical dimensions, including the feeding and other delivery equipment, testing protocol and methodology, qualitative and quantitative data analysis, benchmarking, key performance indicator identification and monitoring, safety, and most importantly a thorough understanding of and respect for the paper machine operation," he said.
The experts interviewed for this article cited several examples of performance chemical use that help improve machine efficiency, promote consistent retention and drainage, increase machine speed, and lower energy consumption.
Kasy King noted the benefits of several classes of chemicals:
* Retention/drainage aids lead to improved white water cleanliness, fewer breaks, fewer deposits, higher speeds, drier sheets entering the press section, and the elimination of clothing/press pick outs.
* Scavengers or trash collectors are very effective in neutralizing charge demand and trapping anionic trash. These benefits lead to higher efficiencies of other additives, lower variation in the process, coated broke coagulation, higher retentions, faster drainage, and cleaner wet ends.
* Low molecular weight cationic polyamines and polyamides can positively impact Yankee dryer adhesion by adhering the sheet to the dryer and tightening up the sheet draw.
* Dry strength aids increase tensile strength, internal bond, and other physical aspects of the formed paper. These physical enhancements lead to fewer web breaks, lower press picking, and better draw control. Many of these strength aids also positively affect retention and drainage.
* Both acid and alkaline internal sizes impart liquid penetration resistance that improves size press operation, coat weight control/uniformity, and ink hold out.
* Defoamers and deaerators both produce less entrained air. The lower air content produces less foam, fewer deposits, improved formation, higher chemical retention, faster drainage, and better sheet formation.
* Biocides improve machine performance by killing biological activity and keeping the machine clean, resulting in fewer boilouts and reduced downtime.
* Fillers and pigments can enhance machine performance by scavenging contaminants (which prevents deposits), lowering sheet shrinkage (which reduces breaks), and by promoting drainage/drying improvements (which promote speed and energy savings).
Brine Ranson noted the example of a fine paper mill that was successfully using a micropolymer/APAM retention and drainage program. However, industrywide economic demands prompted a sheet ash increase along with optical brightener (OBA) use in the wet end. Simultaneously, the mill wanted to increase machine speed. These changes over-stressed the mill's micropolymer program, which was unresponsive to dosage changes and caused variability in silo consistency and FPAR.
To combat this problem, the mill began using a structured organic particulate that provided the following results:
* Improved responsiveness and the ability to lower silo consistency when needed.
* Less FPAR variability at an overall higher FPAR
* A production increase of 450 saleable tons/month
* A 5% improvement in overall machine efficiency (OME), from 87% to 92%.
* Consistent retention and drainage under harsher conditions--higher sheet ash (increased from 15 to 19%), faster machine speeds, and high levels of anionic trash (in OBA high bright grades).
Irenee Philippe noted that combinations of micropolymer and microparticle systems provide the latest technology for papermakers to decouple the mechanisms of retention and drainage (RDF), allowing for unprecedented control of the papermaking process. "Quantified benefits observed with decoupling RDF on high speed, fine paper machines include a 5-10% increase in machine speed and runnability, a 3-5% reduction in energy consumption, decreased need for process additives, and a significant improvement in formation at higher retention levels," he said.
In a different application, Mark Zempel, market manager, retention for Eka, noted that a coated recycled board producer used a nanoparticle system on its largest machine to increase production by 5% for a multimillion dollar payback. Another nanoparticle system application on a large uncoated freesheet machine boosted first pass retention and reduced the amount of filler purchased by the mill. The application of the nanoparticle system also enabled improved formation, increased speed, and enhanced sizing efficiency, he said.
Nalco's Smith noted that one of the more obvious examples of using a performance chemical based solution to improve machine performance is the implementation of a wet end efficiency program to improve on-machine efficiency by enhancing dewatering, which in turn provides improved wet-web strength.
"The improved wet-web strength will reduce web breaks and allow for improved uptime or, if possible, an increase in machine speed--both of which will improve on-machine efficiency," said Smith. "Conversely, the papermaker could also accomplish this by making a capital investment in a shoe press or steam box. Suppliers can assist in this process with a diverse set of tools, from defoamers to nanoparticles to designing and implementing a control or monitoring strategy."
WHAT'S NEXT FOR PERFORMANCE CHEMISTRY?
While current performance chemical technology has provided important benefits to papermakers, new advances in performance chemistry over the next five years may extend the value of performance chemicals in several ways.
According to Phillipe of Ciba, future performance chemicals will exploit synergies between application areas that historically have not been linked, such as RDF and paper whiteness. "These synergies should help develop cost effective programs designed to meet market demand for high brightness and highly filled papers with improved printing characteristics and performance," he said.
Hercules' Ranson noted that increased energy costs have significantly increased pressure on mills to improve efficiency. "In this regard, performance additives play a key role and will arguably become more critical as energy costs consume a larger component of the total cost per ton of paper produced," he said. Ranson forecasted increased demand for:
* chemicals that provide improved gravity drainage (such as advanced retention and drainage technology), allowing for a reduction in dryer energy;
* contaminant control agents (such as pitch and stickies control technology) that reduce machine downtime while maximizing efficiency at critical heat transfer surfaces; and
* microbiological control chemistries (such as ammonium bromide technology) that allow mills to reduce water consumption via increased process stream recycling.
"The opportunity to recover energy value from waste hemicellulose as part of the emerging forest biorefinery concept will generate new applications for performance chemicals to further benefit paper-maker profitability," he added.
Eka's Bengtson agreed that energy will be a critical focus for papermakers. "Energy savings realized by improving wet end drainage alone could more than pay for the novel high performance chemical systems," he said. "High tech interactive chemistry equals cost savings and quality gains."
According to Smith of Nalco, over the next five years performance chemistry advances will more efficiently and effectively deliver performance gains to the papermaker. In terms of efficiency, the focus will be optimal delivery methods to the papermaking process that ensure the cost effectiveness of performance chemistry while eliminating negative impacts on operational stability or finished product quality. In terms of effectiveness, the advanced offerings will be tailored to deliver specific measurable results such as brightness, porosity, or strength, or will improve operational issues such as speed, cull or stability, stated Smith.
"Most importantly, whether papermakers are looking to improve operating efficiency or finished product quality, new offerings will be more targeted, helping mills make needed improvements without the compromises that are often made today," he concluded.
Consultant Kasy King, while less optimistic about development efforts for major new product breakthroughs, saw several key areas where papermakers could possibly move ahead in performance chemical applications.
"Europe is utilizing more deaerators and fewer defoamers for entrained air control. Once this technology takes hold, there will be more focus on preventing the formation of air, and less on treating it," he said. "Prevention versus 'band-aiding' should help save money and perhaps will lead to other preventive measures.
"Another area where I am hopeful for some industry movement is charge balance," he continued. "As we add more cationic materials to the process and as water/fiber recycling increases, wet end charge is moving closer to zero or even becoming positive. This excess positive charge must be balanced with more anionic additives. There is potential for using anionic starches, moving back to using more anionic retention aids/microparticulates, and perhaps developing anionic internal sizing agents."
King also holds out hope that the paper industry will lobby Congress to loosen Food and Drug Administration requirements on residual polymer monomers for food contact grades, thus allowing suppliers to produce higher charge additives. "If this happens, papermakers could use these very high charge density cationic additives in processes that carry high to very high levels of anionic materials and contaminants," he concluded.
ALAN ROOKS, EDITORIAL DIRECTOR
WHAT YOU WILL LEARN:
* How performance chemicals can be cost effectively used to improve the papermaking process
* Specific examples of improvements based on performance chemical applications
* How advances in performance chemistry over the next five years may benefit papermakers
* "Optimization through storage, make down, and feed," by Kasy King, Solutions!, May 2005. To access this article, type the following product code in the search field on www.tappi.org: 05MAYSO31. Or call TAPPI Member Connection at 1 800 332-8686 (US); 1 800 446-9431 (Canada); +1 770 446 1400 (International).
* "A marriage for performance sake," by Kasy King, Solutions!, April 2003. Product Code: 03APRSO29
* "Synergistic effects from performance chemicals," by Kasy King, Solutions!, April 2004. Product Code: 04APRSO45
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|Title Annotation:||PAPER CHEMISTRY|
|Publication:||Solutions - for People, Processes and Paper|
|Date:||May 1, 2006|
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