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SPECIAL EDITION PREVIEW: PaperWeek Canada & BIOFOR International

J-FOR A PAPTAC PUBLICATION

JOURNAL OF SCIENCE & TECHNOLOGY FOR FOREST PRODUCTS AND PROCESSES VOL. 6, NO.1

FEATURING

Kruger’s cellulose filaments advancing toward commercial breakthroughs SunPine, from crude tall oil to green diesel, printing ink and perfume J-FOR’s technical peer-reviewed papers

2017 PAPERWEEK CANADA

www.paperweekcanada.ca

Canada’s premier joint conferences for the Pulp, Paper, Board and Forest Bioeconomy industries.

BIOFOR International Montréal 2017

www.bioforinternational.com

February 13 - 17, Centre Sheraton Montreal, QC, Canada FOR THE ADVANCEMENT OF THE FOREST INDUSTRY

News, Stories, Interviews contributed by:


Value built in paper Kemira’s roots are in the pulp and paper industry and we are here to stay. Working closely together with customers, we continue to invest in R&D to create value through improved process efficiency, productivity and end-product quality. Our leading portfolio and best-in-class application expertise covers the whole process from pulping to coating. Let’s work together to build value into paper. www.kemira.com


News, stories, interviews contributed by: PA

J-FOR

Paper Advance

A PAPTAC PUBLICATION

TABLE OF

CONTENTS SPECIAL ISSUE CONFERENCE PREVIEW

5 EDITORIAL

Greg Hay, J-FOR’s publisher

CONFERENCE PREVIEW SECTION

2017 PAPERWEEK

BIOFOR International Montréal 2017

CANADA

SunPine, from crude tall oil to green diesel, printing ink and perfume

Kruger’s cellulose filaments advancing toward commercial breakthroughs

20

20

13 14 16 19 20 21 22 22 26 27 28 29 31

PaperWeek Canada Conference What to expect at PaperWeek PaperWeek Conference Overview Keynotes at PaperWeek PAPTAC National Awards PaperWeek Program at a Glance 3D Printing Workshop Workshop on Mill Process & Energy Integration BIOFOR International Conference What to expect at BIOFOR International Keynotes at BIOFOR BIOFOR Program at a Glance Registration / Accommodations

FEATURED ARTICLES

TECHNICAL PAPERS

23 Kruger’s cellulose filaments advancing toward commercial breakthroughs

32 SunPine, from crude tall oil to green diesel, printing ink and perfume

34

TECHNICAL PAPERS

In every J-FOR+ issue:

7 8 11

INDEX OF

ADVERTISERS

Industry Pulse PAPTAC Communities PAPTAC Webinars

Published by:

PAPTAC

Pulp and Paper Technical Association of Canada

For inquiries, please contact: PAPTAC 740 Notre-Dame St. W., suite 1070 Montreal (Quebec) H3C 3X6 CANADA Phone: (514) 392-0265

J-FOR

Kemira Kadant Solenis Chesterton Paper Advance Buckman

2 4 10 12 34 64

Publisher: Greg Hay, PAPTAC Executive Director Co-editor: Stéphan Desjardins, Paper Advance Co-editor: Carmie Lato, PAPTAC Production Specialist: Thomas Périchaud, PAPTAC

36

Power dissipation profiles determined from force measurements in a High-consistency TMP refiner by Antti Fredrikson, Lauri I. Salminen, Esko Härkönen

46

Potassium hydroxide pulping of saccharum spontaneum (KASH) M. Sarwar Jahan, Tawhida Akter, Jannatun Nayeem, Purabi Rani Samaddar, Mohammad Moniruzzaman

54

Troubleshooting a black liquor concentrator solids control problem via modelling and simulation Wei Ren, Bruce Allison

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J-FOR

EDITORIAL

A PAPTAC PUBLICATION

Where people, ideas and industry connect Greg M. Hay, Publisher

It is now clear that bioeconomy has become a reality that forest products companies need to consider in their path forward. More and more projects are being launched. More companies are getting on board. And, what was once known, not so long ago, as R&D research material being presented as potential avenues to diversify forest products, is now the object of new projects being built in sites across Canada, North America and throughout the world. And it's growing fast!

Are you staying ahead of the curve? What a fitting theme for the next edition of PaperWeek Canada, which is held jointly with BIOFOR International, where this is true not only for the traditional side of the business but also on the transformation front. Are you staying ahead of the curve on the emerging Management practices; are you staying ahead in terms of Safety leadership; are you ahead of the game in Reliability? PaperWeek will cover the most recent trends and feature experts in these fields and many others, and will provide invaluable benchmarks in terms of where your mill or company is situated in terms of world-leading best practices. Capitalizing on the initial success in 2016, once again PWC and BIOFOR will be running in tandem; setting the stage for the first North American industry must-stop of the year. A true synergetic approach between the forest products and the chemical & end-user sectors, to build a platform for further dialogue and discoveries on forest fibre as source for renewable bio-products. The “stock” for forest fibre and the added-value it can provide to allied sectors is climbing as more and more companies are looking to improve their environmental footprint while maintaining product quality. The two events will be held at a new venue, the Centre Sheraton Hotel in Montreal on February 13-17 2017; and registration will provide access to both conferences. Come discover world-leading programs that cover key aspects of forest products advancement and the new technologies being developed and adapted to the industry’s reality. Renowned keynote speakers, players of academia, the financial sector, research institutes, chemical sectors, manufacturers of the pulp & paper and forest products industry, government entities and much more, will all converge in Montreal for PaperWeek and BIOFOR. Furthermore, coupled with a dynamic multi-sector tradeshow, highly popular Joint sector events on Tissue (Tissue Masters), Packaging (TechPack) and Pulp (PulpEx) will also return, plus an added segment on the Converting industries (ConverTech). Come and upgrade your professional development! Come reenergize your network. We trust your participation will allow you to connect the value of the conference to your business goals.

LEAD ASSOCIATE EDITORS Martin Fairbank Consultant Patrice Mangin CRML/Université du Québec à Trois-Rivières ASSOCIATE EDITORS Thore Berntsson Chalmers Institute of Technology (SWEDEN) Virginie Chambost EnVertis Inc. (CANADA) Christine Chirat Grenoble INP – Pagora (FRANCE) Jorge Luiz Colodette Federal University of Viçosa (BRAZIL) Ron Crotogino ArboraNano (CANADA) Sophie D’Amours Université Laval (CANADA) Robert Dekker (BRAZIL) Gilles Dorris FPInnovations (CANADA) Paul Earl Paul Earl Consulting Inc. (CANADA) W. James Frederick Table Mountain Consulting (USA) Ramin Farnood University of Toronto (CANADA) Gil Garnier Australian Pulp and Paper Institute (AUSTRALIA) Eldon Gunn Dalhousie University (CANADA) Ali Harlin VTT (FINLAND) Mikko Hupa Åbo Akademi University (FINLAND) Mariya Marinova École Polytechnique de Montréal (CANADA) David McDonald JDMcD Consulting Inc. (CANADA) Glen Murphy Oregon State University (USA) Yonghao Ni University of New Brunswick (CANADA) Ivan Pikulik Consultant (CANADA) Risto Ritala Tampere University of Technology (FINLAND) Reyhaneh Shenassa Metso Power (USA) Paul R. Stuart Ecole Polytechnique (CANADA) Trevor Stuthridge FPInnovations (CANADA) Honghi Tran University of Toronto (CANADA)

See you in February!

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A UNIQUE CANADIAN PERSPECTIVE February 13-17, 2017 Le centre Sheraton Montreal Hotel Montréal, Qc, Canada

Recognizing the Forest Fibre’s Value

BIOFOR International Montréal 2017 February 13-17, 2017 Montréal, Canada

Bringing together key players from forest products manufacturers, technology developers, research institutes, chemical and allied sectors, and governments, BIOFOR will provide an incomparable opportunity to connect on all aspects of the rapidly emerging forest bioeconomy.

www.bioforinternational.com


INDUSTRY PULSE FEATURED NEWS ON THE INDUSTRY

Catalyst turns corner

Things are looking up for Catalyst Paper. The company recently reported improved operating results for its most recent quarter ending September 30, 2016. Though results were cooled somewhat by the write-down of a noncash impairment of $186.4 million on fixed assets at the company’s Powell River, Port Alberni and Crofton paper mills, before these losses were considered, Catalyst reported net earnings of $7.6 million. This compares to a net loss of $266 million in the previous quarter.

Trio partners to capture carbon

Domtar to buy adult incontinence products company

Resolute finishes first of three tissue lines

Domtar is buying Home Delivery Incontinent Supplies, a direct-to-consumer provider of adult incontinence products. The deal, valued at approximately $45 million, is expected to close by the end of the year. Direct-to-consumer engagement and interaction is growing, and provides unique consumer and customer insights that are critical to continuously improve the value of our offering," said Michael Fagan, President of Domtar’s Personal Care division. "Adding HDIS's successful high-touch service model and capabilities supports our Personal Care growth strategy."

Resolute Forest Products has wrapped up the commissioning of the first tissue line at its tissue facility in Calhoun, Tennessee. The other two lines will be commissioned by the end of the year. The project, valued at $270 million, is the largest investment the company has made since 2010. Once completed, the facility will be able to produce roughly 66,000 short tonnes of tissue and towel each year.

Cascades to build new converting plant

New papermachine for Kruger’s Crabtree Plant CO2 Solutions, in partnership with a subsidiary of Resolute Forest Products called Fibrek General Partnership and Serres Toundra, is opening a carbon capture unit at a pulp mill in Saint-Felicien, Quebec. The project will cost $7.4 million and will capture up to 30 tonnes of C02 per day from Resolute Forest Products softwood kraft pulp mill , which will then be transported to Serres Toundra’s neighbouring vegetable greenhouse.

Fortress Paper Hemicellulose Separation Project at its Dissolving Pulp Mill A strategic supplement to the already announced birch usage project at the Fortress Specialty Cellulose Mill aimed at extracting hemicellulose from underutilized species such as birch. The Hemicellulose Project will allow the Company to advance its research and development in hemicellulose derivative products.

PA

Paper Advance

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Cascades is building a new tissue converting plant in Oregon. The $64 million investment includes new converting lines and will support the creation of 200 jobs during the construction phase, and 80 permanent positions once that work is completed. The plant will make virgin and recycled bathroom tissue products and paper hand towels. Kruger is adding a paper machine at its Crabtree plant in the Lanaudière region of Quebec. The project, valued at $55 million, will increase the plant’s production by roughly 20,000 metric tonnes each year and will help secure roughly 600 jobs at the facility. Investissement Quebec loaned the company $39.5 million in support of the project. The new paper machine will produce tissue products and is expected to be commissioned next summer.

Pulp by-product finds new life as mine waste cover Green liquor sludge and till have found new applications as cover for mine waste. A closed mine owned by company Boliden, located in Northern Sweden, tested the technology to determine its usefulness in covering over the mine’s waste. Initial results were positive. ‘Green liquor sludge is a by-product from pulp mills’ chemicals recovery process with a high water retention capability [and] low water permeability,” explained Gunnar Westin of SP Processum. “The mix of green liquor sludge and till results in a sealing layer with relatively low water permeability.”

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Communities connecting the right people

The PAPTAC Alkaline Pulping Community – Successful Restart!

Alkaline

The revival of the PAPTAC Alkaline Pulping Community during the summer of 2016 was long awaited and made possible thanks to the great leadership of Doug Barbour of Harmac Pacific, and Robert Dufresne of Resolute FP. Kraft pulping mills across Canada expressed the need to exchange best practices under a well-managed structure. PAPTAC used its tools and experience to set up and promote this group which now comprises over 60 representatives. It didn’t take long for the APC to get back on track, with a 1st webinar entitled “On-Line Kappa Measurement” in September and a 1st face-to-face meeting in October 2016, and both generating high attendance. Based on how this effective restart was, PAPTAC members can be sure to have a lot more coming in 2017!

The PAPTAC Bleaching Community is still on top of its game

Bleaching

The PAPTAC Bleaching Community has always been one of the strongest and most efficient work-group in the industry all around the world, and they kept doing their best in 2016 to offer members a unique forum for mutual support in daily operations. What strikes the most within this community is the constant and active participation of its members across Canada and the US, not only by attending face-to-face meetings in great numbers, but also by sharing and helping each other on a daily basis via their direct email Listserv. Problemsolving, training and on-line sharing has never been more easy and effective, and again in 2016, the Bleaching Community paved the way!

The rise of the PAPTAC Student Community – The Future Starts Now

Students

When PAPTAC created the Student Community, the goal was to build a path for the future workforce and forest companies to meet. These young graduates will soon enter the workforce as engineers, chemists, and eventually managers, and now is the right time to bring together students and their professors with forest companies, and prepare the future of our industry. Dynamic, tech-savvy, environmentally friendly, curious… All these characteristics reflect on the activities of the PAPTAC Student Community: informative sessions on the industry, regular feed on their PAPTAC Students Facebook page, or participation in annual science festivals to promote the industry. These passionate students will soon define our industry, and PAPTAC is proud to support the launch of their careers.

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Safety first with Eastern Canadian Black Liquor Recovery Boiler Advisory Committee

ECBLRBAC

Recovery boiler safety is a must, and thanks to the ECBLRBAC – Network administered by PAPTAC since 2014 – Canada has its own group of industry representatives to look after safety of recovery boilers in our mills. Since PAPTAC took ECBLRBAC under its wing, the participants' base keeps growing at a good pace. Face to face meetings occurring once a year attract more and more mill personnel as the committee gains in popularity. The latest meeting took place in St John at the end of November 2016, which peaked with a tour of the Irving Pulp & Paper Chip Plant and their new digester. Participants were more than delighted with this activity, which will surely inspire the committee for the next meeting.

The PAPTAC Atlantic Branch builds on solid ground and sets the pace for other divisions

Atlantic Branch

Mills and representatives from Eastern Canada were the first to express the desire to revive a regional PAPTAC division in 2011, and what a growth since the return of the Atlantic Branch! The Atlantic Conference is now very well structured and attended, getting invaluable input from involved Maritime’s mills in order to set up a conference that addresses their specific needs. PAPTAC is very proud of the fast growing evolution of its Atlantic Branch, and particularly the fact that it sets the table for the revival of two other groups: the Western and Niagara Branches. PAPTAC member mills clearly expressed the need to establish regional networks. These three branch revivals are very positive signs for the industry!

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The answer is right here. Smart chemistry doesn’t have to be complex. Sometimes all it takes is a conversation. So we work closely with you to analyze your process and water chemistry challenges. Then we connect with the right technologies that can help you achieve your goals.

Experience the simplifying power of collaboration at solenis.com


PAPTAC WEBINARS:

A powerful, easy-to-access training tool and membership benefit We know knowledge transfer is a primary concern for mill management. PAPTAC’s Webinars are designed to help facilitate that transfer through the Association’s powerful communities. PAPTAC’s ever-popular series of webinars relating to topics ranging from papermaking technology, energy, environment, management, pulping, etc. continue to enhance our members’ personal professional development, as well as engage them in their peer communities, all with easy access from their office. In 2016 we delivered 9 one-hour webinars: • • • • • • • • •

Maximizing Profits in P&P through Process Integration On-line Kappa Measurement Assessing Potential Risk of Mill Process Changes on Biotreatment Health Spreading Threading – Recapturing Lost Capacity with Optimized Threading How to Move the Culture to Interdependency An Introduction to Human Performance Improvement (HPI) Wrinkling Retention Programs

This compelling mix of training topics permitted seasoned members, but most importantly junior engineers, to deepen their knowledge and strengthen their expertise and capabilities. The webinars are also helping us build a digital library that will help us deliver, in the near future, a more readily accessible, secure, continued high quality training experience that’s available when and how it’s most convenient for our members.

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When Your Assests Are On The Line Chesterton’s Total System Solutions for Pump Asset Management can improve reliability, reduce life cycle cost, and enhance overall pump operating efficiency and availability. From reliable mechanical seals and bearing protection to advanced bearing lubrication and industrial coatings, Chesterton has the technology and programs to keep your equipment running more reliably and energy efficient. With knowledgeable and experienced local specialists and service partners, Chesterton helps protect your plant’s assets.

chesterton.com/rotating

24570 Š 2016 A.W. Chesterton Company.


SPECIAL CONFERENCE PREVIEW SECTION

2017 PAPERWEEK

February 13 - 17, Le Centre Sheraton Montréal, QC

CANADA

The Annual Conference of the Pulp and Paper Industry in Canada

Staying Ahead of the Curve PaperWeek Canada is the most important annual conference & tradeshow serving the pulp/paper and forest products industry and facilitates the exchange on the latest technology, operation improvements, and business development among the sector’s key players. Under the theme “Staying Ahead of the Curve”, the 2017 edition of PaperWeek will feature an incomparable learning and networking opportunity, bringing together experts from around the world on topics of the highest relevance, as well as an impressive contingent of mill personnel. We look forward to welcoming you and the global pulp & paper industry in Montreal next February! Greg Hay Executive Director PAPTAC

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What to expect at PaperWeek Canada PaperWeek Canada, the number one gathering of the pulp & paper and forest products industry in Canada, will be held Feb. 13-17 2017 at Le Centre Sheraton Hotel in Montreal. Under the theme “Staying Ahead of the Curve”, the conference organizing team is putting together a cutting-edge program covering the key aspects of forest products advancement. PaperWeek is certainly the ‘all in one’ conference, as you will find relevant, diversified and rewarding activities, that will allow you to invest your time valuably in further developing your interests, improving your skills and sharing ideas with your peers.

Here are highlights of what you can expect: Conference sessions worthy of the most deemed technology conferences; the highly popular tracks on Safety, Management, Reliability best practices will return, as well as the solid traditional sessions on Energy, Papermaking, Bleaching and Environment. Joint sector events that are shaping our industry: PaperWeek’s partnering sector events are going to continue to lead the conference with complete programs on Packaging (TechPack), Tissue (Tissue Masters), Pulp (PulpEx) and as well as a newly developed segment on the Converting Industry (ConverTech). A tremendous Tradeshow: where around 50 exhibitors representing our industry worldwide show their products and are eager to interact and demonstrate their expertise to attentive visitors; as it is not unusual to see conversations start in a session room, continue in the hallway later in the day and resume at a booth during the evening reception!

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2017 PAPERWEEK CANADA

Informal Gatherings: there will be reserved spaces, where anyone can lead a conversation, and anyone can sit in to share experiences and build a targeted network. Panels: panel sessions with 4 or 5 invited speakers will revolve around specific themes, an ideal forum where several points of view are expressed and exposed to the audience to generate healthy debate around key issues affecting our industry, daily. Keynote speakers: PaperWeek is known around the world for its daily kick offs and business luncheons keynote presentations. Come hear industry leaders share their views on the industry and give you their take on the future has in store. Trends: Curious to know the latest sector trends? Where is the market heading? How the international stage is going to develop? PaperWeek will be your first North American must-stop of the year! PaperWeek Social Events such as receptions and networking coffee breaks are the most interesting informal interactions among attendees. While the lectures and sessions will provide new ideas, the unique, personal, and insightful conversations you have with other people often happen at our prearranged social events. Do not miss this opportunity! National Awards: PaperWeek is also the National Stage for the presentation of PAPTAC’s prestigious National Awards recognizing industry leadership and advancement. Come to PaperWeek, a valuable investment for both your company and yourself to develop your skills. We trust your participation will allow you to connect the value of the conference with your business goals.

www.paperweekcanada.ca

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Featured Initiatives and Partnerships for P&P Advancement

2017 PAPERWEEK CANADA

Joint sector events that are shaping our industry:

TISSUE

MASTERS

Tissue Masters Conference – PaperWeek’s dedicated segment on the Tissue Sector

The Tissue Sector is now an integral part of PaperWeek. A few presentations a couple of years ago have now grown into a full length track. Tissue Masters has become a unique venue with an emphasis on combining sessions on market, technology and process. The sector’s key players in Canada and abroad are expected to attend and hear the latest information pertaining to tissue production with an overview of market outlooks and process improvements.

TECHPACK

The TechPack Conference at PaperWeek

TechPack is PaperWeek’s dedicated segment of the Paperboard Packaging Industry. With experts covering the latest technology advancements and market updates in the sector, the presentations will also provide updates on some of the most recent implementations & projects that have made the news in the packaging industry.

Pulp EX

The PulpEx Conference at PaperWeek – a comprehensive program on the technology, market and process advancements in pulp

Following the success if its inaugural edition in February 2016, PulpEx returns to PaperWeek bringing together mill representatives, market analysts, suppliers, experts who will discuss the latest advancements in pulp production, technology developments as well as provide insight on the most recent market perspectives. Featuring: Continuous Improvement Bleach cost saving initiatives New technology development in Pulping process Shut down strategy approach Canadian Pulp business update Water and energy conservation in Pulping process; Improvement and new process, etc.

CONVERTECH NEW: ConverTech Conference at PaperWeek A new Converting segment makes its entry at PaperWeek. With expert presentations covering the latest technology advancements, trends and challenges in paper, tissue and paperboard converting operations, we are excited to launch ConverTech as part of PaperWeek's comprehensive program.

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Featured Initiatives and Partnerships for P&P Advancement Conference Sessions: E N E R G Y

Energy Track Reducing energy costs and consumption continues to be at the top of priorities for mills. Come hear about the most recent initiatives, programs and learn from experts in key areas of energy management and efficiency.

TR ACK

M A N A G E M ENT

Returning in 2017! PaperWeek's popular Management Track will expose attendees who are involved in different levels of management to some of the most influential and successful leadership approaches. Managers who have to combine technical skills and human skills will greatly benefit from this program that will discuss effective management systems and the transfer of technical skills to soft skills and to manage in a changing environment.

S A F E T Y

T R A C K

Safety return in 2017 with a complete track focused on Safety Best Practices. This program will feature presentations from experts, consultants and leaders on world-class best practices in safety. A must-attend segment for all mills at PaperWeek.

TR ACK

R E LI A BIL I TY

What is considered world class when it comes to reliability? Where does the pulp and paper industry stand vs. where it needs to be in order to be competitive and vs. what other industries have done? This highly anticipated track returns 2017 featuring experts in reliability with industry best practice case studies, as well as experts from other industries to provide participants the most recent advancements and benchmark standards in operational reliability.

TECH NIC A L

PA

Paper Advance

T R A C K

T R A C K

The Technical Sessions at PaperWeek have always been among the strongest in the world. Come learn from industry experts and hear the latest technology advancements in a variety of fields.

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WHY JOIN PAPTAC? PAPTAC EXPLORES

PAPTAC ELEVATES

PAPTAC PROVIDES

PAPTAC PROMOTES

PAPTAC ASSISTS

PAPTAC IMPROVES

PAPTAC EXPLORES - Where advancements and opportunities arise through the support of an industry-dedicated network PAPTAC ELEVATES - The platform for industry innovation PAPTAC PROVIDES - Means for the interchange of knowledge and expertise among its members PAPTAC PROMOTES - The efficient stewardship of natural resources PAPTAC ASSISTS - In the solution of technical and business challenges facing the industry PAPTAC IMPROVES - The skill level & effectiveness of present and future employees through training and education

CONNECTING PEOPLE PAPTAC plays an essential role in facilitating the exchange of information on a variety of issues related to operations optimization, management and industry advancement. Webinars, e-mail discussion groups, on-line forums, conferences, industry news: a wealth of information accessible to all PAPTAC members.

To learn more about PAPTAC membership or to join, visit the Membership Section at www.paptac.ca or contact the PAPTAC Membership Team (514-392-0265 / tech@paptac.ca)

BUILDING FOR THE NEW PULP & PAPER COMMUNITY

M

TC

Membership

Technical Communities

FW Future Workforce

BI BIOFOR International

PWC PaperWeek Canada

www.paptac.ca


2017 PAPERWEEK CANADA

KEYNOTE SPEAKERS An impressive line-up of keynote speakers are looking forward to sharing their thoughts, views and perspectives throughout the conference

The Honourable James Carr (invited) Minister of Natural Resources Soile Kilpi Director, Strategy Poyry Management - New York

Glenn Mason Assistant Deputy Minister Natural Resources Canada Pedro Chang Deputy CEO Paper Excellence

Jean Jobin President and COO Cascades Tissue Group Stéphane Demers Director of Operations Suncor Energy

Mike Lafave Senior VP & COO Kruger Inc. Roger Laramée Group Advisor – Safety RioTinto Global

Sylvain Lhôte Director General CEPI – the Confederation of European Paper Industries

Henry Mintzberg Author & world-renowned Management specialist

Visit paperweekcanada.ca for the complete list of keynote speakers and additions to the keynote roster

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PAPTAC National Awards National Awards for business leasdership, research & technical papers

The PAPTAC Business Awards recognize excellence in specific management areas and provide an opportunity to promote the highest levels of business leadership in the Canadian pulp & paper and forest-based industry. This recognition is awarded on the largest national platform during PaperWeek Canada, organized by PAPTAC. Awards for research and technical papers, and recognizing service to the Canadian pulp and paper industry and PAPTAC are also conferred at the Annual Meeting of the Association (PaperWeek Canada).

Be sure to join us for this unique occasion to recognize and celebrate excellence in the Canadian pulp and paper industry. The presentation of the awards will take place at the Centre Sheraton Hotel in Montreal QC, during the Business Luncheons and Welcoming Reception. The Business Luncheons draw key players from the industry across Canada and Internationally, and gathers Company CEOs, VPs Operations and Finance, mill managers, superintendents, technical staff, government representatives, suppliers, researchers, consultants, press and others. Visit http://www.paptac.ca/index.php/en/association-paptac/national-paptac-awards.html for details

Mill Managers Breakfast Roundtables The Mill Managers Roundtables have become a key component of PaperWeek, an event several mill managers look forward to exchange on a number of issues with their counterparts. It has grown into a dynamic forum and a unique opportunity to get news ideas, learn from different management cultures and benchmark best practices. The Mill Managers Roundtables will be led by Eric Ashby, General Manager at Domtar Windsor. They will take place Tuesday and Wednesday AM Feb 14 and 15. Come prepared!

Eric Ashby General Manager Domtar Windsor

Topics this year will be focused on updates from each participant on their respective operations, and key points of discussions and presentations will address: . Reliability . Continuous Improvement . and Safety

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2017 PAPERWEEK

PROGRAM AT A GLANCE February 13 to 17, 2017 • Le Centre Sheraton

CANADA

MONDAY 13 FEBRUARY 2017 Morning

Afternoon 17:00 - 18:30

Welcoming and Awards Reception

TUESDAY 14 FEBRUARY 2017 Morning 7:00 - 9:00

Mill Managers’ Roundtable

8:30 - 10:00

PaperWeek Opening Breakfast Panel

10:00 - 10:30

Networking Session in Tradeshow

Afternoon 13:00 - 13:30 13:30 - 15:00

Coffee and Dessert in Tradeshow PulpEx Conference Kick off Reliability Track Safety Track Bleaching Track

15:00 - 15:30

Networking Session in Tradeshow

10:30 - 12:00

Reliability Track Process Control Session Papermaking Track Bleaching Track

15:30 - 17:00

PulpEx Conference Reliability Track Safety Track Bleaching Track

12:00 - 13:00

KEYNOTE LUNCHEON

17:00 - 18:30

NETWORKING RECEPTION in tradeshow

ALL DAY (10:00 - 18:00)

TRADESHOW

Workshop on Mill Process and Energy Integration (all day)

WEDNESDAY 15 FEBRUARY 2017 Morning 7:00 - 9:00

Mill Managers’ Roundtable

8:30 - 10:00

TechPak Conference Kick off

8:30 - 10:00

PulpEx Conference Papermaking Track

10:00 - 10:30

Networking Session in Tradeshow

15:00 - 15:30

Networking Session in Tradeshow

10:30 - 12:00

PulpEx Conference TechPack Conference Energy Track

15:30 - 17:00

TechPack Conference Tissue Masters Conference Energy Track Management Track

12:00 - 13:00

KEYNOTE LUNCHEON

17:00 - 18:30

NETWORKING RECEPTION in tradeshow

ALL DAY (10:00 - 18:00)

TRADESHOW

Afternoon 13:00 - 13:30 13:30 - 15:00

Coffee and Dessert in Tradeshow Tissue Masters Conference Kick off TechPack Conference Energy Track Management Track

Workshop on Mill Process and Energy Integration (all day)

THURSDAY 16 FEBRUARY 2017 Morning 8:30 - 10:00

ConverTech Conference Kick off Tissue Masters Conference Mechanical Pulping Session

10:00 - 10:30

Networking Session in Tradeshow

10:30 - 12:00

Tissue Masters Conference ConverTech Conference Environment Session

12:00 - 13:00

BUSINESS AWARDS LUNCH / KEYNOTE

ALL DAY (10:00 - 16:00)

TRADESHOW

Afternoon 13:00 - 13:30 13:30 - 15:00

Coffee and Dessert in Tradeshow ConverTech Conference

15:00 - 15:30

Networking Session in Tradeshow

Workshop on Mill Process and Energy Integration (all day)

NB: This program is preliminary and is subject to changes.


3D Printing Workshop BIOFOR International 2017 / Wednesday February 15, 2017 Where are the opportunities for the forest industry? Additive Manufacturing or 3D printing is emerging as one of the game-changing disruptive technologies of our time. The potential for 3D printing has gone beyond prototyping. Homes and furniture may be fabricated by 3D printing, with significant potential for products of the forest industry. Hear the latest developments in manufacturing technologies, feedstocks and applications, and opportunities for wood- based biomaterials and advanced fibre and building products. Join international experts in 3D printing and bioproducts at Biofor International 2017, the international conference for the forest-based bioeconomy. Contact information: Joe Aspler or Lyne Cormier 3dprint@fpinnovations.ca

PROCESS INTEGRATION

Who should attend: The one-day workshop is open to all with an interest in 3D printing: particularly those who would like to join the discussion on what additive manufacturing could do for the pulp, paper, and advanced forest products industries

CanmetENERGY

OPTIMIZING HEAT MANAGEMENT IN THE PULP AND PAPER INDUSTRY Because pulp and paper mills consume large amounts of energy, they are constantly looking to improve process efficiency in order to reduce energy costs. More and more, mills also wish to increase their ability to generate power. Given the strong interactions between energy systems, water networks, and power generation, paper mills are ideal candidates for process integration (PI), a well-established global approach for optimizing steam and hot water production, heat recovery, and power generation through cogeneration. Thanks to this training, participants will broaden their knowledge of energy integration, becoming more familiar with the main analysis tools used and how they are applied in the pulp and paper industry. The training also covers several projects related to kraft and thermomechanical processes. All day Thursday February 16, Centre Sheraton Montreal during PaperWeek Canada

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Kruger’s cellulose filaments

advancing toward commercial breakthroughs by Mark Williamson, Paper Advance

Thirty in-mill papermaking trials and pressroom trials have been encouraging. Specialty grades are a target. Composite materials and concrete mix applications look promising. It's been over three years since the strategic alliance was formed between FPInnovations and Kruger Biomaterials Inc. to develop the process technology and commercial applications of cellulose filaments (CF), initially conceived at FPInnovations' Pointe Claire, QC laboratories. The business model of this alliance allows Kruger to gain a lead in CF manufacturing, while FPInnovations members have access to CF from the Kruger Biomaterials plant for applications development. In the interim, a lot of progress has been made. The CF pre-commercial plant in Trois-Rivières, QC was designed and built on a fast-track schedule, in less than 7 months. High quality CF was produced within 2 months of start-up, and production was ramped up to the designed 5 t/d capacity in 9 months. That capacity makes it the largest cellulosic biomaterial plant in the world. However, that 5 t/d capacity is for one shift per day only, so there is ample room for more production – up to 6,000 t/a for 24 h/7 day operation. FPInnovations' intellectual property portfolio has been strengthened and expanded with patents on the process granted in 6 countries, several patents filed on new CF applications, and additional applications in the pipeline.

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The FiloCell™* product is aimed at paper strength reinforcing, new grade development and lightweighting applications, and new groundbreaking uses in composite materials, concrete mixes and many diverse applications. The fastest progress in field-testing and applicationdevelopment has been in the Canadian paper industry where 30 on-machine trials have been concluded so far, some of them covering several weeks of machine production time. Strength enhancement in paper is a natural application for CF since it has a very good fiber to fibril bonding potential made possible by a high aspect (length to width) ratio, which is achieved by gently peeling fibrils from kraft pulp fibers while still maintaining the length. That results in a paper sheet which has stronger wet and dry strength for the same basis weight.

Improved or unique paper properties Balázs Tolnai, General Manager Technology at Kruger's Industrial Product Division, emphasizes the value of CF in a paper furnish: "CF provides extraordinary strength which allows significant furnish optimization and reduced chemical dosages. It also permits the development of new products." Regarding the paper machine trials, Tolnai continues, "The majority of the trials were focused on developing new grades with improved and/or unique properties or to produce grades that had been out of the capabilities of the paper machine. Some machines have

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never been able to run low basis weight because of the wet web strength and poor runnability. Now, with CF, the wet web strength is improved as well as the dry strength. With the help of CF we are able to produce high strength, light weight products and we are also able to translate the strength coming from the CF to other properties (like opacity) by adjusting the machine operation and furnish composition. During the trials the machine operators have become accustomed to the different drainage profiles and machine draws required for CF-enhanced grades." Trial runs have been on paper machines using both mechanical pulp and mixtures of mechanical and chemical pulp. Wood-free grade trials are being planned. He continues, "CF quality can be adjusted to match end user needs. We have full flexibility, but it is a trade-off between achieving certain quality parameters and paper machine productivity. The quality is checked online every fifteen minutes by an analyzer developed by FPInnovations.

low spots in the sheet, the paper performs better in the pressroom. A LWC grade paper with CF had one third of the breaks than paper with no CF at the same strength."

Trials in a press room show that break frequency has been reduced by two-thirds with CF-enhanced paper. This is because sheet strength is more uniform as shown in the histogram chart.

Good dispersion of CF is required to untangle the filaments. The mill trials have used several types of commercial pulpers with success. A mobile platform designed by FPInnovations is also available. To date, CF has been shipped in bulk bags at 30% solids. A 100% dry CF film was produced in a pilot machine trial at InnoFibre in Trois-Rivières. This dry film form avoids extra shipping costs for full time commercial applications. The film is fully dispersible with standard papermaking equipment.

New applications require collaboration An online analyzer developed by FPInnovations measures CF tensile strength so it can be closely controlled.

Press breaks one third with CF CF has also proved its value in printing plants using trial rolls of CF-enhanced publication papers. Tolnai explains, "CF not only can improve strength of the paper, but also improves its uniformity by eliminating low and high points and tightening the distribution of the sheet strength. Since we are able to eliminate the

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Papermaking is a natural application for cellulose filaments, however there are a multitude of potential applications in other industries. Composite materials and concrete mixes are enticing and encouraging so far. This type of research and development will take more time and collaboration with universities and other development partners. Tolnai says, "The universities and research centres together with relevant and dedicated industrial players are a must for the development of CF applications. Even though they are at the laboratory scale some significant discoveries have been made already, including high

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CF is currently shipped at 30% solids in bulk bags. A dispersible 100% dry sheet has been produced on InnoFibre's pilot paper machine in Trois-Rivières.

strength high performance concretes, technology to produce dry and dispersed CF, and lightweight CFcontaining plastic composites." Kruger Biomaterials, in collaboration with UQTR, (Université de Québec à Trois-Rivières) has developed a surface treatment which allows for the production of dried CF which is "fluffy" and dispersible. That is a key requirement for composites. The water uptake of the CF containing composites drops to extremely low levels.

Concrete strength improved "We have been working with the University of Sherbrooke on developing CF- containing high performance concretes. We are looking at specialty applications, not commodity. The main benefit is improved rheology and strength properties with minimal CF addition. In certain grades with 0.1% CF addition we can improve the concrete strength by 1 or 2 orders of magnitude," he explains. Since the concrete mix with CF is thixotropic, its viscosity decreases with shear forces, thus making it more fluid. This produces a more homogeneous concrete with less phase separation before the concrete is set. With lower viscosity the pumping costs to the top of high skyscrapers are lower.

* FiloCell is the registered trademark for the cellulose filaments produced and commercialized by Kruger Biomaterials, a Kruger Inc. subsidiary.

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Flexural strength of cement paste has been improved remarkably by small amounts of CF.

Breakthroughs coming? Over the next year or two what could be the imminent breakthroughs that would make CF a fully commercial product? Tolnai responds, "First, the commercialization of specialty paper products. Within the next year we hope to have a 24/7 application on a paper machine. That would be a success. Then our expectations are for development of light weight composites and high performance concrete." "The current CF plant with 24/7 operation will be able to supply the market needs for a couple of years," he explains. A production-scale plant of 100 t/d is in line with Kruger's projections of a market of 150,000 t/y for the papermaking applications and a similar size market for other applications. Mark Williamson has over 40 years of engineering, product marketing and journalistic experience in the pulp and paper industry.

Kruger Inc. founded Kruger Biomaterials in 2013. Its mandate is to produce and commercialize FiloCell biomaterial following the commissioning of world’s first cellulose filament demonstration plant in June 2014. (www.kruger.com)

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SPECIAL CONFERENCE PREVIEW SECTION

BIOFOR International MontrĂŠal 2017

February 13 - 17, Le Centre Sheraton, Montreal, QC

The International Conference for the forest-based Bioeconomy

Recognizing the Forest Fibre’s Value Following a successful inaugural edition in February 2016, the highly anticipated BIOFOR International Conference returns to Montreal in 2017. Dedicated to the emerging forest bioeconomy, BIOFOR International will run parallel to the highly attended PaperWeek. Bringing together key players of academia, the financial sector, research institutes, forest products manufacturers, chemical sectors and governments, BIOFOR will provide an incomparable opportunity for the forest products sector and allied stakeholder industries to connect on all aspects of the rapidly emerging forest bioeconomy, across North America and worldwide.

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What to expect at BIOFOR International Following a very successful first edition, the BIOFOR International Conference is back! Held in conjunction with PaperWeek, the most important conference dedicated to the forest products sector in Canada, the BIOFOR conference is dedicated to the advancements of the forest bioeconomy. BIOFOR will revolve around 3 main focus areas: MARKET development / PROCESS advancements / and new TECHNOLOGY. In order to help maximize synergy between the forest and bioceconomy sectors and promote dialogue, the two events will take place under the same roof: Feb. 13-17 2017 at the Centre Sheraton Hotel in Montreal. One single access to go from one to the other conference will certainly incite people to network and make valuable connections! Within the MARKET segment, targeted presentations and panels will set the table for a comprehensive overview of the current market potential and deployment of the forest bioeconomy. Well-known private and public companies will provide pertinent examples to show the current projects and initiatives underway. While Government representatives and policy organizations will describe the funding accessible to support innovation networks and clusters and depict tangible impacts on the industry and its players. The PROCESS advancements segment will focus on the new developments of processes and programs and actual discoveries. Renowned mills will describe the possibilities of biorefinery start-ups in the context of creating economic growth in Canada’s forest communities. A Biomaterials session will be part of this segment and will cover steps to use existing pulp mills as a basis for bioeconomy development from the forest sector. Successful stories will demonstrate paths from the traditional process to a new vibrant future full of possibilities. Under the TECHNOLOGY segment, participants will have the chance to hear technical presentations from universities, engineering, organizations and mills. Pilot projects and applications stories will attest of the new developments achieved up to now. The audience will have the opportunity to learn from these experiences and exchange with speakers and peers. Come to BIOFOR and expect to meet, all under the same roof, key players from academia, the financial sector, research institutes, chemical sectors, forest products manufacturers, governments’ entities and much more!

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KEYNOTE SPEAKERS An impressive line-up of keynote speakers are looking forward to sharing their thoughts, views and perspectives throughout the conference

BIOFOR

Glenn Mason Assistant Deputy Minister Natural Resources Canada

Jean Hamel Vice President Pulp, Paper and Bioproducts FPInnovations

Gurminder Minhas Managing Director Performance Biofilaments

Peter Axegård Vice President, Bioeconomy Strategy Innventia/RISE Bioeconomy

Michael Rushton Vice President, Chief Operating Officer Fibria Innovations Inc.

International Montréal 2017

Marco Lucisano Vice-President Director, Business Area Papermaking & Packaging Innventia AB/RISE Bioeconomy

Trevor Stuthridge Executive Vice President FPInnovations

Sandy Marshall Executive Director Bioindustrial Innovation Canada

Warren Mabee Canada Research Chair in Renewable Energy Development Queen’s University

Visit bioforinternational.com for the complete list of keynote speakers and additions to the keynote roster

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PROGRAM AT A GLANCE February 13 to 17, 2017 • Le Centre Sheraton

BIOFOR International Montréal 2017

MONDAY 13 FEBRUARY 2017 Morning

Afternoon 17:00 - 18:30

Welcoming and Awards Reception

TUESDAY 14 FEBRUARY 2017 Morning

Afternoon 13:00 - 13:30 13:30 - 15:00

Coffee and Dessert in Tradeshow Updates from leading research organizations

10:00 - 10:30

Networking Session in Tradeshow

15:00 - 15:30

Networking Session in Tradeshow

10:30 - 12:00

BIOFOR Kick off Panel

15:30 - 17:00

Green Chemicals Market Potential

12:00 - 13:00

KEYNOTE LUNCHEON

17:00 - 18:30

NETWORKING RECEPTION in tradeshow

WEDNESDAY 15 FEBRUARY 2017 Morning 8:30 - 10:00

Afternoon Governmental initiatives and programs 3D Printing Workshop (all day)

13:00 - 13:30 13:30 - 15:00

Coffee and Dessert in Tradeshow Acceleration of regional Bioeconomy projects

10:00 - 10:30

Networking Session in Tradeshow

15:00 - 15:30

Networking Session in Tradeshow

10:30 - 12:00

Air Transport Biofuels opportunities

15:30 - 17:00

R&D and Technology session

12:00 - 13:00

KEYNOTE LUNCHEON

17:00 - 18:30

NETWORKING RECEPTION in tradeshow

THURSDAY 16 FEBRUARY 2017 Morning 8:30 - 10:00

Afternoon Biorefinery 1 R&D and Technology session

13:00 - 13:30 13:30 - 15:00

Coffee and Dessert in Tradeshow Biomaterials R&D and Technology session

10:00 - 10:30

Networking Session in Tradeshow

10:30 - 12:00

Biorefinery 2

15:00 - 15:30

Networking Session in Tradeshow

R&D and Technology session

12:00 - 13:00

BUSINESS AWARDS LUNCH / KEYNOTE

NB: This program is preliminary and is subject to changes.


KNOWLEDGE MATTERS PAPTAC assists in the solution of technical challenges facing the industry

Come learn from industry experts and hear the latest technology advancements in a variety of fields during PaperWeek Canada 2017

2017 PAPERWEEK CANADA

The Annual Conference of the Pulp and Paper Industry in Canada

2017

February 13-17 Le Centre Sheraton MontrĂŠal, Qc, Canada

The Technical Sessions at PaperWeek have always been among the strongest in the world.

www.paperweekcanada.ca


Registration & Accommodations

PAPTAC Member

PAPTAC Non-Member

All Week

950.00

1225.00

Monday only (13 Feb)

550.00

800.00

Tuesday only (14 Feb)

550.00

800.00

Wednesday only (15 Feb)

550.00

800.00

Thursday only (16 Feb)

550.00

800.00

Registration Fees - $CAD Delegate

Student Member (must be able to provide a valid ID if asked)

295.00

Emeritus / Retired / Honorary Life Member

475.00

Speaker / Session Moderator

475.00

Note: An additional $250 (plus applicable taxes) will be added to all fees quoted above for on-site registrations. Everyone is encouraged to pre-register.

Hotel Reservations: Please visit the following link for on-line hotel reservations: https://www.starwoodmeeting.com/events/start.action?id=1605100040&key=4969893 or call the Centre Sheraton MontrĂŠal Hotel directly at 514-878-2000 (toll free 1-800-325-3535) by January 12, 2017 and mention the code PAPERWEEK2017 to obtain the conference group rate of $185/night (standard room). This rate will be in effect from February 12 to February 18 for all PaperWeek Canada 2017 participants. Reservations made after January 12th are subject to availability and group rate will be honored solely depending on the category of rooms available at time of reservation. In-room internet access is not included in the standard room rate. Other room categories available to delegates are deluxe rooms at $225/night and Club Level rooms at $255/night. Check in time is: 3:00 PM, Check out time: 12 noon. An early departure fee equal to 50% of the daily rate will apply if an attendee checks our prior to the confirmed check-out time without due notice. Notice is due by 6 pm the day before you foresee checking out in order to have the fee waived.

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SunPine, from crude tall oil to green diesel, printing ink and perfume by Sören Back, Paper Advance

Piteå in northern Sweden is well-known for the production of kraftliner at SCA and Smurfit Kappa, in total more than 1.1 million tonnes, and may probably be the world's kraftliner capital. Less known is that SunPine in Piteå was first in the world to extract green diesel from crude tall oil. Their latest milestone was on 13 June when the new biorefinery part to extract rosin from crude tall oil in their plant was inaugurated.

The remarkable fact, which shows the strong confidence the owners had in this totally new process, is that the project without further ado in one step went from a process, verified in laboratory scale only, to a full scale tall oil biorefinery. This could maybe serve as an example for also other actors wanting to walk a new and greener path. Sometimes one must dare to jump into the water knowing that the ice is gone but without knowing the water temperature.

The story behind the development of SunPine is very interesting, and in some aspects unique, and hence well worth telling. The idea of extracting green diesel from crude tall oil came from Lars Stigsson, a Swedish chemist and innovator, who in 2005 studied how to do it technically. He worked together with the chemist Valeri Naydenov who developed a ready model for the process to extract green diesel from tall oil.

Piteå, an obvious choice

From laboratory to industry scale in one step Lars Stigsson promoted the idea and got Sveaskog, Sweden's biggest forest owner, Södra, the big market pulp producer, and Preem, the largest fuel company in Sweden, interested. As they put 100 MSEK (11 million USD) each into the project of building a biorefinery to extract green diesel from crude tall oil, their interest was obviously not just lip service. Sveaskog, Södra and Preem, together with Lars Stigsson's company Kiram, formed Sunpine AB in 2006. A fullscale production facility was set up in record time, an investment of around 350 MSEK (38 million USD), and was taken into operation in 2010. 32

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"It might not seem very logical to establish a tall oil biorefinery in Piteå, which is in the very northern part of Sweden," says Magnus Edin, CEO of SunPine. "However, there are logical reasons for it. Piteå is located at the sea with a harbour with existing available storage tanks and big enough to allow tankers, transporting the green diesel to Preem's refinery in Gothenburg. On the raw material side we have two sulphate mills next door and as we are located in a harbour we have good transport possibilities of crude tall oil from all sulphate mills along the Swedish coast. So the industrial logic is there."

Three products are now four "Previously we extracted three products from the crude tall oil: green diesel, bio oil and turpentine. However, in 2013 we started a cooperation with the Dutch chemical company Lawter who were looking for rosin to be used as raw material in their products.

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The results of this cooperation were that we developed a process how to extract rosin from the crude tall oil, a decision was taken to invest in this process and Lawter entered the group of owners buying a ten per cent share of Sunpine AB."

Sunpine's refining process

This product is mixed into Preem's product Evolution Diesel and used in diesel vehicles. All in all, two percent of Sweden's total diesel consumption of five million m3 is today produced in Piteå by Sunpine. "From our refinery we also get about 50 000 tonnes of bio oil from the crude tall oil we buy," says Magnus Edin. "This product is sold back to pulp mills where it is used e.g. in their lime sludge reburning kilns."

Today Sunpine therefore refines 180,000 tonnes of crude tall oil to green diesel, bio oil, rosin and turpentine. The process is not chemical but purely a physical one in which tempeFrom odour to fragrance ratures, pressures and flows are Magnus Edin, CEO of SunPine, varied in the process. First water and "An odd product in our portfolio is the in front of the biorefinery. turpentine is removed, as they have 2,000 tonnes of turpentine we extract the lowest boiling temperatures. Step every year. It is hardly possible to two is the distillation column, the heart in the process, imagine the end-usage of it," Magnus Edin says with where the green diesel ends up at the top and a rosin a smile. "Anyone who has got a bit of turpentine on rich fraction at the bottom of the column. Thereafter the clothes knows that it is impossible to wash away and that the smell is almost as bad as the famous the rosin fraction is upgraded and at a temperature of 195 oC fed into heated containers to avoid the Swedish "surströmming", a fermented hate or love object of Baltic herring. However, the perfume industry, rosin to solidify during transportation to Lawter's plant in Belgium. The rosin is processed and used in of all industries, has found a method of getting rid of products like printing inks, tape and glue but also in the smell but keeping the turpentine's sticking capability. By adding the cleaned turpentine to perfumes chewing gum. it prolongs the perfume molecules' lifetime, and hence The whole production of green diesel is transported fragrance, on a perfumed skin somewhere on the body." by tankers to Preem's refinery in Gothenburg where oxygen, sulphur, nitrogen and aromatic components Sören Back, journalist for Paper Advance with 39 years’ experience from pulp and paper industry are removed resulting in the final diesel product.

Process operators Krister Franzén and Staffan Johansson in the control room.

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Bottles of crude tall oil, green diesel and the final diesel end product.

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INFORMING THE PAPER INDUSTRY PROFESSIONALS Paper Advance and Le Maitre Papetier play an essential role in facilitating the exchange of information on a variety of issues related to operations optimization, management and industry advancement coupled with an industry-respected international editorial team.

PA Paper Advance

LE MAĂŽTRE

PAPETIER

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THE PULSE OF THE SECTOR We have our finger on the pulse of the sector in Canada and worldwide. With critical, up-to-date and diverse content focusing on pulp, paper, board and tissue manufacturing, converting operations, bioeconomy, technology reports, process optimization, sciences and exclusive interviews with top industry leaders, we offer a unique platform for all industry practitioners to exchange and offer information and to facilitate industry excellence. in production.

TO SUBSCRIBE TO OUR WEEKLY E-NEWS BULLETIN:

www.paperadvance.com or www.lemaitrepapetier.ca

Paper Advance and Le MaĂŽtre Papetier are the official partners of PAPTAC network.


J-FOR TECHNICAL PAPERS


POWER DISSIPATION PROFILES DETERMINED FROM FORCE MEASUREMENTS IN A HIGH-CONSISTENCY TMP REFINER ABSTRACT

ANTTI FREDRIKSON*, LAURI I. SALMINEN, ESKO HÄRKÖNEN Thermomechanical pulping is a process that comminutes wood into fibres and develops the fibres into paper-grade pulp by purely mechanical means. The process consumes considerable electrical energy. Consequently, much effort has been expended to reduce this energy, and to do this, one must first understand how the energy is being used. Given the extreme difficulties of making measurements inside a refiner, much of the effort made has focussed on indirect methods such as temperature profiles and pulp analysis. However, forces on fibres create the refining effect and the consequent energy consumption. In recent years, new sensors have been developed to measure forces on bars during refining. In this study, these sensors have been used to measure bar force in multiple zones in an operating refiner for different plates, and these forces have been linked to temperature and power expenditure in each radial zone. An important finding of this work is that temperature profiles cannot be used to estimate power profiles.

INTRODUCTION

Mechanical pulp, in particular thermomechanical pulp (TMP), maintains its position as a very important virgin fibre raw material component in packaging board and printing paper manufacture, even after many printing paper mill shutdowns in North America and Scandinavia. Mills are facing a more challenging future because their energy and raw material costs are increasing and national regulations are downsizing their already small operating margins. Many attempts and great innovations have been made to decrease the energy consumption of the mechanical pulping process, the latest being the ATMP process [1]. Most improvements have been focussed on raw material flow manipulation, operating variables, and chemical treatments. Incremental development of machines and their wear parts by supplier companies continues to yield innovations, but the defibration phenomenon remains as a very black box. In this paper, TMP refining is quantified by refiner power dissipation profiles,

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which bring new information to develop an energy-efficient TMP process. TMP refining is a complex process. Its optimization involves multiple disciplines (wood science, thermodynamics, and mechanics) and multiple targets (energy, fibre cost, and quality). Material flows and refining forces have been difficult to measure and model. During chip refining, particles on the order of 10 mm are comminuted to 100-micrometre fines and

ANTTI FREDRIKSON

A Fredrikson Research & Consulting Ltd., Vähäkuja 2A2 FI-40520 Jyväskylä, Finland *Contact: antti@afrc.fi

microfibrils [2–4], and simultaneously a large amount of water is evaporated to steam. Comminution [5] and material transport through the refiner are handled by the numerous elements (bars and dams) of the refiner plates. When a wooden chip or pulp pad is facing the refiner plate bar, a force is generated [6]. In this work, these forces have been measured with four refiner force sensors (RFS) in a pilot-scale TMP refiner [7].

LAURI I. SALMINEN

A Fredrikson Research & Consulting Ltd., Vähäkuja 2A2 FI-40520 Jyväskylä, Finland

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ESKO HÄRKÖNEN

Jauhokalliontie 1 E 14, FI-87200 Kajaani Finland


TRADITIONAL AREA CONTRIBUTIONS

Refining modelling by lubrication theory (Frazier [8]), entropy models (Karlström and Eriksson [9]), flow phenomena (Härkönen et al. [10]), flow models (Huhtanen et al. [11]), and friction models (Miles and May [12]) always makes some assumptions about the main variables of the defibration process. In lubrication theory, pulp, water, and steam are treated as fluids, and the model only estimates plate wear. In their friction model, Miles and May [12] used only one coefficient of friction for all the pulp in the refiner, whereas huge transitions in scale and fineness and particularly in pulp consistency are known to occur. Huhtanen et al. used fluid models for the entire defibration, even though a non-continuous flow field is known to exist in the breaker bar zone. Karlström and Eriksson used only one energy transport distribution model as measured by Backlund [13] and therefore lacked a view of uncoupled results. Härkönen et al. used refiner plate gap flow modelling in three dimensions to describe the various physical phenomena involved in refining. The more comprehensive applicability of this model has not been demonstrated [10]. Measurement devices in the TMP refiner plate gap must endure several simultaneous challenges. Steam pressure, vibration, wear, and electromagnetic fields together must be overcome before reasonable measurements of defibration mechanisms can be made. Earlier, Atack and Stationwala [14] and most recently Eriksen [15] have extensively tested pressure measurements in a mill refiner. Berg [16] and Gradin et al. [17] have used strain gauges to measure forces against complete refiner plate bars. Härkönen, Backlund [18], and Olender et al. [19] have used piezoelectric elements with smaller, bar-mimicking heads to perform force measurements. In this study all measurements were carried out in high-consistency refiners. The lowconsistency process environment with only two phases (liquid and solid), obeys very different principles. Temperature measurements in refiner plate gaps [10,14,20–26] have been used to clarify refining conditions inside the

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refiner. Here, the temperature profile was used to estimate fibre pad densification or the variations in pulp volume fraction in the plate gap, similarly to Härkönen and Tienvieri and to Illikainen et al. [27,28]. From many stroboscopic and visual evaluations of high-consistency refining, it is evident that the whole refining area is not continually occupied by fibres. The RFS-sensor results support this observation by showing occurrence ratios (i.e., activity probabilities) below 80% [19,29]. Based on high-speed photography, Stationwala et al. [30] estimated fibre coverage to be between 55% and 80% in the second-stage refiner. Alahautala et al. [31] reported that pulp coverage reached 100% in the inner zones, but was less than 60% at the outer periphery of a primarystage refiner. Moreover, in intensity studies carried out by Miles and May [32] and Huhtanen et al. [33], it was estimated that every bar-to-bar crossing involved energy transfer to fibres, which in the light of visual inspection underestimates the loading on refiner bars. With complete fibre coverage in the Miles and May and Huhtanen models, the intensity would be lower than measured according to direct RFS measurements. The reason for the poor correlation between intensity and fibre wall thickness reduction as a function of refining amount might be the unrealistic fibre coverage of the intensity model [34]. In this research, a method was used to establish a power profile within the TMP refiner by means of a shear force exerted on refiner stator bars. Kerekes used forces on bars and the occurrence ratio to calculate forces on fibres [6]. This study went further by measuring the force distribution and the calculated radial power profile [35]. The forces acting on the fibre pad in the refiner were measured with refiner force sensors (RFS) [36]. Olender et al. have shown the usability of RFS systems in mill TMP refiners [19]. Highconsistency refining has three distinct, but overlapping objectives: to reduce wood to its constituent fibres, to retain the integrity of a considerable fraction of these fibres, and to induce the maximum amount

of flexibility and fibrillation into the separated fibres and fine fibre fragments [37]. All three objectives can be quantified using RFS technology in a pilot refiner. A method to analyze refining impacts using average force actions on fibre pad in the refiner has been explained in Fredrikson and Salminen [7]. Previous studies of force distributions lacked proper measurements in the breaker bar zone, and hence too much emphasis was placed on fibre treatment in the small plate gap area. Härkönen et al. calculated that in the first-stage refiner, about 50% of the energy consumption is used before the steam turning point, i.e., the maximum temperature point in the refining area. Their calculation was based on energy and mass balances and on the pulp sample consistency at the maximum temperature point. MATERIALS AND METHODS

The trials took place in the KCL pilot plant at Espoo, Finland, with a Metso RGP 44inch (disc diameter 1.12 m) single-disc TMP refiner. The refiner is powered by a 1340-kW variable-speed motor, and in this study, the rotational speed was set to 1500 RPM. Norway spruce (Picea abies) roundwood chips were used throughout the trials, which consisted only of primary-stage refining. The production rate of the refiner was 700 kgod /h. The two refiner rotor segments (fine: JRGP42693 and coarse: JRGP42653) used on the rotor positions were manufactured by Metso Paper Valkeakoski Oy. These bidirectional plate patterns are shown in Fig. 1. The conical cross section of the plate gap, the taper, is shown in Fig. 8 with power dissipation profiles. The plate pattern data of the two refiner-plate models are given in Table 1. The refiner segments cover the surface of the refiner disc from 330 mm to 560 mm radius. The stator disc area inside the 330-mm radius is flat and therefore can generate little or no shear load. Therefore, it has been assumed that the central region does not contribute to refining. This particular refiner is fed with

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Fig. 1 - a) Fine segment type; b) coarse segment type.

chips through the rotor side, meaning that feeding operates similarly to double-disc refiners. The pilot refiner was equipped with VTT’s plate gap instrumentation system. Refiner bar forces were measured using fourth-generation University of Victoria and FPInnovations Refiner Force Sensors [38,39], and temperatures were measured using 18 thermocouples. The force sensors were located at radii of 410 mm, 450 mm, 490 mm, and 540 mm, whereas the temperature probes were distributed evenly between the plate inner edge (radius of 330 mm) and the outer edge (radius of 560 mm). All the temperature probes were located on the bar face because if the probes had been in the grooves, they would have had a damped response [25]. The force sensor output was recorded at a rate of 300 kHz, and the data were analyzed using a custom MATLAB™ program. The newly developed force analysis method [7] has advantages over the origi

TABLE 1

Rim S1 Rim S2 Rim S3 Rim S4

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Plate pattern data of fine and coarse segments.

Fine Coarse Fine Coarse Fine Coarse Fine Coarse

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nal [40] RFS data analysis method in that it provides more detailed outputs, but it results in slightly lower shear force readings. Analysis of forces gave the following quantities describing the shear force events: the average shear force over the event [N] and the occurrence ratio (OCR) [%]. The occurrence ratio is here defined as the number of detected events divided by the number of bar passing periods at a specific radius during the total duration of the data set. Shear forces were analyzed over long periods (one to three minutes) because high-consistency refining typically exhibits temporal variation over short periods. It was assumed that the shear force measured by the sensors represented refining action at that particular point in the refining area. This technique is similar to that used by Kerekes and Senger, who derived refiner power using a bar-crossing approach in low-consistency refiners [41]. It was also assumed that the suspension of wood, fibres, and water was loaded by the

N.O. bars 264 168 624 312 672 432 936 480

“Bar width, mm” 3,5 5 2 3 2 3 1,5 3

“Bar height, mm” 9-26 6-8 6-9 6 6-9 6 6 6

“Groove width, mm” 5,5 9 2,5 4 2,5 4 2 4

sensor head and that the shear force generated by steam drag was negligible. Temperature values were recorded by KCL’s pilot-plant Wedge™ system at a rate of 0.5 Hz [42]. The analyzed values of shear force (average shear force of the event per representative area Fsi (units N/m2)) (Fig. 2) and the occurrence ratio OCR (units %) were used to calculate the power distribution inside the refiner. The shear force per unit of refining area was calculated for the four rims. With the average radius of the rim and the rotational speed of the rotor plates, the power for each of the rims could be calculated. Here, constant and even material flow through the refining zone was assumed. If the refining power were equally distributed over the annular refining area, the distributed cumulative load would then be linear as a function of radius. Because this is unlikely, the refiner force sensors will bring new information to our general understanding of these phenomena. In this example case, the net refiner power was 720 kW. The measured refiner power is read from the main motor frequency converter. The refiner idle power was subtracted from total power to obtain net power. Typical idle power for a pilot refiner operating at 1500 RPM is 79 kW. The area represented by event Aiei (the area related to the measured force) was assumed to be the sensor tip length in the radial direction multiplied by the bar pitch (bar width + groove width), as shown in the shaded areas of Fig. 2. The plate pattern of the rotor plate affects the sensor event area. The average shear forces and occurrence ratios were assumed constant over the whole rim area. The rim boundaries were determined by the plate pattern and the radial position of the corresponding sensors, as shown in Fig. 3. The areas of the rims were not allowed to overlap and were assumed independent of the plate pattern in the calculations. The rims were chosen so that the sensor could be expected to represent refining in that rim as well as possible. Originally, the sensor locations were not freely determined because they

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TABLE 2

Rim areas for pilot TMP reďŹ ner. Area, m2 0.215 0.111 0.082 0.192

Rim 1 Rim 2 Rim 3 Rim 4

TABLE 3

Avg - r, m 0.393 0.456 0.489 0.531

Representative event areas for ďŹ ne and coarse plate patterns.

Event 1 Event 2 Event 3 Event 4

Fine, m2 5.48E-05 3.02E-05 2.84E-05 2.52E-05

Coarse, m2 8.82E-05 4.41E-05 4.41E-05 4.41E-05

Fig. 2 - Area of the sensor event is shown in green.

were attached to the segment by means of individually designed perforations. The equation for the power P in the whole area of the rim is:

(1) where Fi is the average shear force on sensor i in Newtons; OCR is the occurrence ratio as a whole number;

Ri is the average radius of rim i; RPM is the rotational speed of the refiner rotor [1/min]; Ai_event is the representative area of an event for sensor i in square metres; Ai_rim is the rim area in square metres, and the scaling coefficient is (2) The areas of the rims and the sensor events as well as the average radii are listed in Tables 2 and 3. The first-stage refining trials were performed to distinguish the refining characteristics of two different plate mod-

els: fine and coarse (see Fig. 1). The stator plate pattern (also the fine pattern) as well as all the other trial conditions were held constant. Refiner power was varied from 500 to 1200 kW by adjusting the refiner plate gap. The accuracy of these power estimates can be verified by adding them together and comparing the result to the measured net powers. In principle, these two values should match. The following example illustrates a possible disparity in the values and the methods developed to cope with the situation. RESULTS Power in the Refining Zones

Fig. 3 - Rim areas for sensors S1 to S4. Only one plate segment (of twelve) is shown here, but rim areas are calculated for the whole periphery. As an example, the outer (rout) and inner (rin) radii of rim 1 are given.

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The power in the refining-zone rims, that is, calculated based on bar forces, was highest in the inner sections of the refining zone (Fig. 4). In the example, the power in the innermost rim was approximately 420 kW. The power of individual rims and their calculated cumulative power as a function of motor power are shown in Fig. 4. Figure 4 shows that the calculated cumulative power and the measured motor power were not equal. In this case, the difference was 65 kW. This lag varied from small negative values (-50 kW) up to +300 kW depending on refining conditions. The explanation for this lag in power levels might be that the forces are too small to be detected at all (limited signal/ noise ratio), too large to be measured correctly (limited measurement range), or changing too slowly to be detected (signal

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Comparison of Different Plate Models

Fig. 4 - Power of individual rims (squares) and radially cumulative power (line) for typical first-stage refining. Motor power and the gap between it and the calculated cumulative power are shown in blue.

interpretation). Force measurements in these studies were based on piezoelectric elements, and their amplifiers feature some charge decays. Hence, if a constant load is applied to the sensor, the output decreases to zero within 0.4 milliseconds. Because this difference between motor power and cumulative power exists and better evaluations could be made with accurate power values, the cumulative power was modified by adding the power lag of the measurements. The shape of the temperature profile was used in addition to

the cumulative power profile. This change is helpful in comparing different trials with different lags between motor power and sensor-based cumulative power. In the example, the normalized temperature profile had the shape shown in Fig. 5, and the additional segmented power curve with total power of 65 kW looked like Fig. 6. The final power profile curve, which includes the sensor-based power and the power difference correction, typically looks like the green curve in Fig. 7.

Fig. 5 - Radial temperature distribution in the plate gap. The shape of the temperature profile is used to distribute the undetected load over the refiner radius. The black line and the left y-axis represent plate gap taper. The purple curve and the right y-axis show the plate gap temperature profile as a function of refiner radius.

40

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The performance of two different plate models (see Fig. 1) was compared under similar refiner operating conditions. Because refiner power varies from trial to trial, the comparison is made using relative power for clarity. Figure 8 shows that the pulp pad between the refiner plates was loaded differently. The fine plate pattern with greater taper was loaded more at the inner parts. For the fine plate, 50% of total power was already consumed before reaching a radius of 390 mm. The coarse plate was loaded more at the outer periphery. The pulp properties measured at the refiner discharge for fine and coarse plates are presented in Table 4; the refining conditions are also listed. The cumulative power profiles provided by the RFS and the calculations reveal where in the plate gap chips and pulp are refined. The shear forces, occurrence ratios, power of the sensor rim areas, and the difference between sensor-based power and motor power are listed in Table 5. Although the cumulative power profiles differed substantially (Fig. 8), only a small difference could be seen in the temperature profiles (Fig. 9). Plate taper also has an effect on both plate patterns, as evidenced by the temperature maxima at the radius where taper changed markedly.

Fig. 6 - Temperature correction to the cumulative power profile. Total power of this profile is 65 kW. The power correction is shown in kilowatts on the y-axis and the refiner radius in millimetres on the x-axis.

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Effect of Refiner Pressure

Fig. 7 - Cumulative power with (green) and without (purple) temperature correction.

TABLE 4

Properties of pulp refined with fine and coarse plate patterns and the corresponding refiner operating conditions.

“SEC, “CSF, “FL-LW, “Power, “Dilution MWh/tn” ml” mm” kW” water flow, l/s” Coarse plates 1.13 535 1.95 745 0.43 Fine plates 1.01 640 2.14 712 0.43

TABLE 5

“Production rate kgod./h” 661 705

“Plate gap, mm” 0.7 0.3

Force measurements for coarse and fine plate patterns. In the case of coarse plate pattern, total motor power was 745 kW and sensor-based power 77 kW lower. For the fine plate, motor power was 712 kW and the power gap 65 kW. 2

1 Shear force [N] Occurrence ratio [%] Power [kW]

Coarse 3.6 38 208

Fine 5.0 36 431

Coarse 3.4 37 230

Fine 1.0 37 98

3 Coarse 1.4 29 58

Fig. 8 - Cumulative power profiles of fine and coarse rotor plate pattern at the primary stage. Taper of the plates is drawn to characterize the shape of the plate gap for both plate models. Local plate gap clearance is shown on the left y-axis, relative power on the right y-axis, and radial position on the x-axis.

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4 Fine 0.4 23 21

Coarse 1.3 36 172

Fine 0.5 28 96

Two refiner casing pressures (3 and 5 bars) were compared with the coarse rotor plates. Higher refiner casing pressure focussed the refining power more strongly in the outer periphery, as shown in Fig. 10. This example emphasizes again that besides temperature, a casing pressure increase changes refining also in dissipation patterns. At the outer periphery, the plate gap is smaller, bar passing frequency is higher, and these changes might have compensating effects together with higher temperature. Nevertheless, pulp properties (CSF and fibre length) were almost unchanged, as shown in Table 6 along withthe refining conditions. The shear forces, occurrence ratios, sensor rim area powers, and differences between sensor-based and motor power are listed in Table 7. DISCUSSION

TMP refiner instrumentation is a laborious procedure that yields unique knowledge of high-consistency refining phenomena. Together with process understanding, new ideas, and well-reasoned trials, it provides an invincible tool to improve energy efficiency and mechanical pulp quality. Rim power calculations show that the powers of the innermost and outermost rims are large compared to the middle rims. Although the sensor positions in

Fig. 9 - Temperature profiles of fine (blue triangles) and coarse (red circles) rotor plate patterns at the first refining stage. Plate gap clearance is shown on the left y-axis, temperature on the right y-axis, and refiner radius on the x-axis. Black (stator), blue (fine rotor), and red (coarse rotor) lines illustrate plate gap taper shape.

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Fig. 10 - Cumulative power profiles of 3- and 5-bar refining pressure with coarse rotor plate pattern in the first refining stage. Local plate gap clearance (black and red solid lines) is shown on the left y-axis, relative load (red and green dashed lines) on the right y-axis, and radial position on the x-axis.

Fig. 11 - Temperature profiles of 3- and 5-bar refining pressure with coarse rotor plate pattern in the first stage. Temperature (green line) of 5-bar refining is shown on the right y-axis, temperature (red line) of 3-bar refining on the left y-axis, and refiner radius on the x-axis.

TABLE 6 Pulp properties for 3- and 5-bar refining pressure with coarse plate pattern. Coarse plates 3 bar 5 bar

“SEC, “CSF, MWh/tn” ml”

“FL-LW, mm”

“Power, kw”

1.13 1.12

1.95 1.91

745 742

535 512

the stator plate were fixed, the boundaries between areas were decided subjectively by the authors. With a large inner section rim area, the power for the breaker bars might also have been exaggerated. This might cumulate the power on the innermost rim together with the fact that the forces are largest there. The taper of the refining area has a strong effect on the density increase of the refined fibre pad in the outer regions of the refining area. Refining action is greater when the fibre pad has higher density. The refiner force sensor (RFS sensor) can measure only fast changes in force. It has been assumed here that some of the shear force remains constant over a substantially long period (seconds). Through charge decay in the piezoelectric sensors,

TABLE 7

“Production “Plate rate, kgod./h” gap, mm” 661 661

0.7 0.6

the sensor output decreases to zero, but the force does not. Therefore, RFS sensors cannot be used as a sliding friction measurement, but rather serve as a peak force measurement of the corner force directed to the refiner bars. The lag between measured motor power and force sensor-based cumulative power could originate from two mechanisms. One is the load generated outside the measurement area, i.e., in the centre of the refiner. The other is based on the properties of the piezoelectric sensor, namely the decay in output charge at constant force input. The charge decay time of the piezoelectric element in the RFS sensor is approximately ten bar-to-bar passages. In other words, some of the refining events might be longer than ten bar-passing

Shear forces, occurrence ratios, and power of rim areas 1–4 for 3- and 5-bar pressure refining. Total motor power in 3-bar refining was 745 kW and the sensor-based power 77 kW lower. For the higher pressure, power was 742 kW and the power gap 255 kW. 2

1 Shear force [N] Occurrence ratio [%] Power [kW]

42

“Dilution water flow, l/s” 0.43 0.40

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3 bar 3.6 38 208

5 bar 0.5 31 25

3 bar 3.4 37 230

3 5 bar 2.3 38 157

3 bar 1.4 29 58

4 5 bar 0.8 35 35

3 bar 1.3 36 172

5 bar 2.0 37 271

periods, in particular when the fibre pad is more uniform and the rotor plate grooves are full of pulp. Then the individual bar edges are not generating detectable impacts, which are needed to pick up events from the raw signal [7]. Refining would be characterized more as a continuous sliding in that area of the refiner. This phenomenon was seen over different sensor positions, but especially in the fine section of the refining area. Analysis has shown that pulp coverage could be more than 80% in the fine zone [31,43]. The power dissipation profile quantifies the work on fibres in the plate gap, whereas the temperature profile illustrates fibre flow. This flow is dependent on refiner control and fibre pad properties. A denser fibre pad increases the occurrence ratio as well as fibre flexibility through a temperature rise, thereby affecting the power profile. It is expected that a power increase leads to a temperature increase. Despite ongoing effort, knowledge of the thermal softening of the fibre pad [28], wood, and fibres [44] is incomplete. Figure 11 shows that the normalized shapes of the temperature profiles look the same. This could mean that similar fibre pads were treated with different power dissipation profiles in these two cases. CONCLUSIONS

Based on the findings of differing power

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dissipation profiles for similar temperature profiles, it can be concluded here that power profiles are not merely a function of temperature profile, and hence that the power profile cannot be estimated based only on the temperature profile. Perhaps most importantly, the methodology and findings of this study open new possibilities to investigate refining phenomena in TMP refiners. Examples are the effects of taper, bar pattern, and temperature. The measured power dissipation profiles and corresponding temperature profiles show that two plate patterns treat chips differently and that their loadability is different. These observations provide guidance on which parts of the plate pattern should be developed and improved for more energy-efficient high-consistency refining. This conclusion would not be possible without working measurements and analytical technology. Two different plate models have been found to generate different power dissipation profiles. The corresponding temperature profiles look more similar, and hence one can be tempted to use the more easily measurable temperature profile as the shape of the power profile. The other example presented here shows that different power dissipation profiles can be obtained from similar temperature profiles. With these findings, it can be confidently stated that power profiles are not merely a function of temperature profile and further that no estimates of power profile can be made based on temperature profile. For printing paper and CTMP mills, plate patterns can be modified to emphasize refining in the breaker bar zone while still operating with safe refiner plate gaps. The strong influence of comminution at the beginning of the refining process has a positive effect on developing flexible and fibrillated fibres as needed. Plate patterns can be changed at every refiner shutdown, which happens typically every 1000 hours of operation. This periodic opportunity gives operators a chance to react to seasonal variations of raw material and electricity prices and make the best use of their refiner at each moment of production.

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Plate gap temperature measurements are in use in modern TMP and CTMP mills. These data can be helpful in evaluating the stability of the refining process, and in some mills, sophisticated calculation models can even predict Canadian Standard Freeness of pulp from temperature measurements. However, shear force measurements in mill refiners are still too expensive and vulnerable to be implemented in the everyday operation of paper and pulp mills. Some companies could use shear force measurements in mill refiners, but only in campaigns lasting a few weeks. In the future, disruptive refiner plate development should be carried out through measurements of plate gap temperature profile and shear force.

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ACKNOWLEDGEMENTS

The authors acknowledge Risto Kuttila from Metso Paper Oy for discussions and support in thermocouple technology. We would like to thank Andritz, MReal, Stora-Enso, UPM, Tekes, and the Academy of Finland (grant No. 138623) for their financial support.

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tiguing Pre-Treatment”, Nordic Pulp and Paper Research Journal, 27(2):168172 (2012). Olender, D., Wild, P., Byrnes, P., Ouellet, D., and Sabourin, M.J., “Forces on Bars in High-Consistency Mill-Scale Refiners: Effect of Consistency”, International Mechanical Pulping Conference, TAPPI, 730-775 (2007). Atack, D., “Fundamental Differences in Energy Requirement Between Mechanical Pulping Processes”, International Mechanical Pulping Conference, EUCEPA, Session VI: No. 5 (1981). Olender, D., Wild, P., Byrnes, P., Ouellet, D., and Sabourin, M.J., “Forces on Bars in High-Consistency Mill-Scale Refiners: Effect of Consistency”, Nordic Pulp and Paper Research Journal, 23(2):218223 (2008). Bankes, A., Wild, P.M., Ouellet, D., Behrouz, S., Siadat, A., and Senger J., “Refiner Force Sensor”, Canada patent US006840470B2 (issued Jan. 11, 2005). Olender, D., Wild, P., Byrnes, P., Ouellet, D., and Sabourin, M.J., “Forces on Bars in High-Consistency Mill-Scale Refiners: Trends in Primary and Rejects Stage Refiners”, Journal of Pulp and Paper Science, 33(3):163-171 (2007). Kerekes, R.J. and Senger, J.J., “Characterizing Refining Action in Low-Consistency Refiners by Forces on Fibres”, Journal of Pulp and Paper Science, 32(1):1-8 (2006). Kahala, J., “Missing Link in Process Efficiency Enhancement”, Paperi ja Puu, 90(4):48-49 (2008). Stationwala, M.I., Atack, D., and Karnis, A., “Distribution and Motion of Pulp Fibres on Refiner Bar Surface”, Journal of Pulp and Paper Science, 18(4):J131J137 (1992). Salmi, A., Salminen, L.I., Engberg, B.A., Björkqvist, T., and Hæggström, E., “Repetitive Impact Loading Causes Local Plastic Deformation in Wood”, Journal of Applied Physics, 111(2):024901 (2012).

Journal of Science & Technology for Forest Products and Processes: VOL. 6, NO. 1


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POTASSIUM HYDROXIDE PULPING OF SACCHARUM SPONTANEUM (KASH) ABSTRACT

M. SARWAR JAHAN*, TAWHIDA AKTER, JANNATUN NAYEEM, PURABI RANI SAMADDAR, MOHAMMAD MONIRUZZAMAN Saccharum spontaneum (Kash), a crop that grows in Bangladesh, has characteristics similar to bagasse (Saccharum officinarum). For economic reasons, a small-scale pulp mill cannot have a recovery system, which causes serious environmental problems Therefore, potassium hydroxide (KOH) and KOH-anthraquinone (AQ) pulping of kash have been investigated and compared with corresponding bagasse pulping. Kash was easily delignified to kappa number 12.5 with a pulp yield of 52.9% under conditions of 14% KOH as NaOH for 2 h at 150°C. Under these conditions, pulp yield in the soda (NaOH) process was 0.3% lower with higher kappa number. Both bagasse and kash pulps were bleached by D0EpD1 bleaching sequences, and the highest brightness (86.6%) was obtained from kash pulp in the KOH-AQ process with a viscosity of 30.1 mPa.s. The unbleached and bleached pulps were beaten in a PFI mill, and their papermaking properties were evaluated. The kash pulp showed slightly better tear index and lower tensile index than the corresponding bagasse pulp. Pulp yield, kappa number, and papermaking properties of kash KOH-AQ pulp were better than those of the corresponding bagasse pulp. Potassium-based pulping black liquor was also applied as a soil amendment and found to be beneficial for soil properties and growth of Red amaranthus. Compared to non-amended control soil, black liquor increased Red amaranthus growth by 2.7 times.

INTRODUCTION

Renewable sources of energy and consumer products are required to maintain sustainable development in the modern world. One such renewable resource is lignocellulose. The main source of lignocellulosic raw material is wood, which comes from forests. Due to environmental concerns, nonwood plant and agricultural residues are gaining in importance for pulp and energy production. The main raw materials for pulping in Bangladesh are bamboo, bagasse, gamai and gewa. North-

M. SARWAR JAHAN

Bengal Pulp and Paper Mills (NBPM) was the only bagasse-based pulp mill in Bangladesh. The NBPM mill was shut down due to an inadequate supply of bagasse. Sugar production in Bangladesh has decreased in recent years, and consequently the surplus bagasse supply has also decreased. In this context, the pulp mill needs additional raw material similar to bagasse. Saccharum spontaneum L. is a perennial herbaceous plant belonging to the Poaceace family. S. spontaneum (kash) has

TAWHIDA AKTER Pulp and Paper Research Department of Chemistry, Division, BCSIR Laboratories, Eden Girls College, Dhaka, Dr. Qudrat-i-Khuda Dhaka Road, Dhaka 1205, Bangladesh Bangladesh *Contact: sarwar2065@hotmail.com

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JANNATUN NAYEEM

Pulp and Paper Research Division, BCSIR Laboratories, Dhaka, Dr. Qudrat-i-Khuda Road, Dhaka 1205, Bangladesh

similar characteristics to bagasse (S. officinarum) and could increase the amount of raw material available to a small-scale bagassebased pulp mill. For economic reasons, a small-scale pulp mill cannot have a recovery system, which causes serious environmental problems. Black liquor treatment is a major concern in a small-scale pulp mill using nonwood fibres as a raw material for papermaking [1]. An effective way to solve the problem of black liquor pollution from nonwood pulping processes

PURABI RANI SAMADDAR

Department of Chemistry, Eden Girls College, Dhaka Bangladesh

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MOHAMMAD MONIRUZZAMAN

Soil &Environment Research Division, BCSIR Laboratories, Dhaka, Dr. Qudrat-iKhuda Road, Dhaka 1205, Bangladesh


TRADITIONAL AREA CONTRIBUTIONS

is to develop new technology that potentially converts black liquor into fertilizer [2–4]. Huang et al. [3] reported some preliminary results of pulping wheat straw with an NH4OH-KOH mixture that effectively reduced the amount and impact of black liquor. Experimental results indicated that the rate of delignification was 85.12% and the pulp yield was 49.65% under suitable pulping conditions. Rainey et al. [4] studied the pulping of arundo, sorghum, and bagasse to kappa number 20 using KOH and anthraquinone to produce a bleachable pulp suitable for making photocopier paper and tissue products. The main goal of this research was to find a suitable raw material that wasclose to bagasse in its characteristics, so that cooking could be carried out without any modification of the bagasse-based pulp mill. Similarly to bagasse, S. spontaneum consists of two parts: the inner parts, mostly made up of parenchyma cells (Fig. 1), and the outer parts, mainly made up of fibres. A few studies have been carried out on bioethanol production from S. spontaneum [5–7]. S. spontaneum is one of the most promising future biomass feedstocks for fuel ethanol production because of its ability to grow quickly without requiring any economic input [8]. A few investigations have shown the possibility of using it as a pulping raw material [9–13]. In our earlier study, soda and soda-AQ pulping of S. spontaneum were carried out [11]. Pulp yield was about 53%–61% with a Kappa number of about 16–29. It was also shown that S. spontaneum contains

Fig. 1 - Light micrographs of bagasse and kash.

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20%–35% pith as dry matter, which was removed by prehydrolysis before sodaAQ pulping [12]. Pre-hydrolyzed pulp had fewer fines, resulting in lower drainage resistance (°SR) than its non-prehydrolyzed counterpart. Delignification of S. spontaneum was also done by formic acid followed by peroxyformic acid and produced a pulp yield of 45%–48% with residual lignin of 2%–4% [13]. Formic acid/peroxyformic acid pulp was bleached to 83% brightness in alkaline peroxide bleaching. Therefore, it can be a potential lignocellulosic source to supplement raw material in a bagassebased pulp mill. In this investigation, the chemical and morphological characteristics of bagasse and S. spontaneum were examined. Potassium hydroxide (KOH) and KOHAQ pulping of S. spontaneum (kash) were done and compared with sodium hydroxide (NaOH) and NaOH-AQ pulping. Similarly, bagasse pulping was carried out for comparison. Pulp bleachability in D0EpD1 sequences and papermaking properties were also evaluated. The black liquor generated from the KOH pulping was also used as a soil amendment, and its effect on the growth of Red amaranthus was studied. MATERIALS AND METHODS Materials

S. spontaneum and bagasse were collected from the Pakshi, Pabna. Raw materials were cut to 0.5–1 cm in length. The moisture content of the raw materials was determined for subsequent experiments.

Morphological properties - For mea-

surement of fibre length and width, S. spontaneum and bagasse were macerated in a solution containing 1:1 HNO3 and KClO3. A drop of macerated sample was placed onto a slide. The slide was placed under an image analyzer (Labomed LX 400 equipped with Digipro 4.0 software) to acquire an image that could be used to measure fibre length and width. Chemical analysis

The hot-water solubility (T207 cm99), 1% alkali solubility, extractives (T204 om88), Klason lignin (T222 om98), viscosity (T230 om99), and ash content (T211 om93) were determined in accordance with TAPPI test methods. Holocellulose samples were prepared by treating extractives-free meal with NaClO2 solution (14). The pH of the solution was maintained at 4 by adding CH3COOH–CH3COONa buffer, and the α-cellulose content was determined by treating holocellulose with 17.5% NaOH (T203 om 93). Ash content was determined in a Nuive muffle furnace at 525°C according to T 211 om-93. Pulping

Pulping of S. spontaneum and bagasse was carried out in a 20-ml capacity small-scale bomb. Four bombs were fitted in an oil bath that was electrically controlled and heated. Pulping was carried out under the following conditions: - Active alkali (both NaOH and KOH): 14%, 16%, 18%, and 20% as NaOH. - Time and temperature were fixed at 150°C for 120 min. - Liquor to feedstock ratio: 6:1. - AQ: 0 and 0.1% on OD raw material. For pulp evaluation, S. spontaneum and bagasse were cooked in a 5-l capacity batch cylindrical digester heated by means of electrical resistance and rotated by a motor. The cooking conditions were selected based on the optimum conditions in small-scale cooking. The normal charge was 300 g of moisture-free raw material. After the digestion time was com-

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pleted, pulp was washed with tap water until all chemicals were removed. Pulp yield was determined gravimetrically from the oven-dried weight of raw material. Pulp evaluation

S. spontaneum and bagasse pulps were beaten in a PFI mill for different revolution. Handsheets of about 60 g/m2 were made in a Rapid Kӧthen Sheet Making Machine according to German Standard Method number 106. The sheets were tested for tensile (T494 om 96), burst (T403 om 97), and tear strength (T414 om 98) according to TAPPI standard test methods.

liquor (PL), Recommended fertilizer dose (RF), and Recommended fertilizer and pulping liquor (RF+PL)) and three replications. RF was constituted by N-P-K-S. In RF+PL, K was replaced by the K content in the PL. Harvesting time of Red amaranthus was four weeks. Recommended fertilizers were based on the Bangladesh Agriculture Research Council Guide 2012. The recommended fertilizers were 0.66 g/ pot urea (N), 0.34 g/pot triple super phosphate (P), 0.18 g/potash (K), and 0.04 g/ pot gypsum (S). The amount of pulping liquor per pot (10 kg soil) was 15 ml. RESULTS AND DISCUSSION

Bleaching

Pulps were bleached by a D0EpD1 bleaching sequence. For bleaching, 35 g pulp was taken. The ClO2 charge was 2%, and temperature was 70°C for 60 min in the D0 stage. The pH was adjusted to 2.5 by adding dilute H2SO4. In the alkaline extraction stage, temperature was 70°C for 120 min, and the NaOH and H2O2 charges were 2% and 0.5% respectively. In the D1 stage, the ClO2 charge was 0.5, and the pH was adjusted to 4.5 by adding dilute alkali. Field trial of Red amaranthus using black liquor as fertilizer

Black liquor was collected from KOH pulping, neutralized by dilute sulphuric acid, and used as fertilizer for Red amaranthus. The potassium (K) content in the black liquor was measured by an atomic absorption spectrophotometer and found to be 1.21 g/l. A field trial was conducted according to a randomized block design with four treatments (Control (C), Pulping TABLE 1

Chemical and morphological characteristics of kash and bagasse.

Holocelluloses (%) α-cellulose (%) Lignin (%) Pentosan (%) Extractives (%) 1% alkali solubility Hot-water solubility (%) Cold-water solubility (%) Ash (%) Fibre length, L (mm) Fibre width, D (µm) Slenderness ratio (L/D)

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Kash Bagasse 65.8 65.4 41.6 41.3 17.3 18.1 25.1 23.6 0.85 1.2 36.2 35.8 10.8 6.6 6.4 10.4 6.8 1.97 1.23 1.01 19.0 17.1 59.1 64.7

Chemical characterization

The chemical compositions of bagasse and kash are shown in Table 1. The coldwater and hot-water solubilities of kash were higher than those of bagasse. The cold-water treatment removes a part of the extraneous components like tannins, gums, sugars, inorganic matter, and coloured compounds that are present in lignocellulosic biomass, whereas the hot-water treatment also removes starches. The higher water solubility adversely affects pulp yield. Acetone soluble extract was 1.2% for bagasse and 0.85% for kash. Acetone extractives included waxes, fats, resins, and low-molecular-weight carbohydrates. Acetone extractable content precipitates and adversely affects process equipment runnability by blocking the openings in the Fourdrinier wire. The one-percent NaOH solubilities of bagasse and kash were 35.8% and 36.2%, which were higher than bamboo (24.7%), lemon grass (30.6%), and sofia grass (28.2%), but lower than rice straw (57.7%) and wheat straw (50.4%) [15]. The higher NaOH solubility was possibility due to the presence of a low molar mass of carbohydrates and other alkali-soluble materials. Lignin percentages were 18.1% for bagasse and 17.3% for kash. The Klason lignin content of bagasse was slightly lower than the value reported by Andrade and Colodette [16]. Hurter [17] reported that

the lignin content in bagasse was in the 19%–24% range. The lignin content of the kash used in this study was slightly higher than in Komolwanich et al. [18], but lower than that in Scordia et al. [7]. This can be traced back to differences during harvesting, storage, and transport, as well as in the habitats of the raw materials used [19]. Lower lignin content indicates easier pulping of bagasse and kash. The α-cellulose content of plant biomass positively influences pulp yield during chemical pulping [20,21]. The cellulose content of lignocellulosic raw materials also determines papermaking properties [20,21]. Table 1 shows similar holocellulose and α-cellulose contents in bagasse and kash (65% and 41%). Scordia et al. [7] found that total carbohydrates accounted for 61.5% of S. spontaneum, whereas the α-cellulose content was 36.8%. In another study, α-cellulose content in bagasse was found to be 45.4% [22]. This difference can be attributed to differences in location. Because arabino-xylan is the main hemicellulose in other monocots such as corn stover, wheat, rye, barley, oats, rice, and sorghum [23,24], the pentosan content in bagasse and kash was determined. The pentosan content in bagasse was 25.1%, and that in kash was 23.6%. The exact percentages of arabino-xylans were 2.1% and 21.5% respectively, as shown elsewhere [7]. In another study, the arabino-xylan content in bagasse was found to be 26.1%, which is close to the value found in this study [25]. Hemicelluloses are an important component in papermaking because they facilitate fibre bonding. Molin and Teder [26] showed that fibres with high cellulose to hemicelluloses ratio had lower tensile stiffness and tensile index. Schönberg et al. [27] showed that the tensile index was increased after sorption of xylan on fibres. The role of xylan in ibres was further investigated. Chemical sorption of xylan was found to increase Scott bond significantly, further supporting the significance of xylan for bonding ability [27]. The mineral components of lignocellulosic biomass can be represented as

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TRADITIONAL AREA CONTRIBUTIONS

ash content. Higher ash content is undesirable during refining and recovery of cooking liquor. The main difference between bagasse and kash is related to ash content, which is higher for kash (6.8%) than for bagasse (1.97%). The ash content in bagasse is close to that found by Jiménez et al. [28]. High ash content in S. spontaneum (kash) was also observed by Scordia et al. [7]. It is well established that transition metals such as Mn, Fe, and Cu negatively affect pulp bleachability (hydrogen peroxide and oxygen) and bleaching selectivity [29]. From the above discussion, it can be seen that the chemical characteristics of both raw materials are similar, suggesting similar pulping behaviour. Morphological characteristics

Table 1 also shows the morphological characteristics of S. spontaneum and bagasse. Fibre length for S. spontaneum was 1.23 mm, which was shorter than bagasse (1.01 mm). Fibre diameter for both raw materials was similar (17–19 μm) and close to that of bamboo (16.8 μm) and lemon grass (16.3 μm) [15]. Longer fibre length was associated with higher tearing strength of paper [30,31]. Fibre diameter and cell-wall thickness controlled fibre flexibility. Cell-wall thickness affects most paper properties, including tensile strength, burst strength, and folding endurance. Paper made of thick-walled fibres has low tensile strength, burst strength, and folding endurance, whereas paper formed by thin-walled fibres is dense and well-formed [30,31]. The slenderness ratio

TABLE 2 Pulping of kash and bagasse by KOH and NaOH processes. Raw material KOH NaOH/KOH Anthraquinone NaOH charge (% as (%) Kappa Pulp yield Kappa Pulp yield NaOH) (%) number number (%) Kash 14 0 52.9 12.5 18.3 52.6 16 0 50.0 11.3 16.5 50.0 18 0 48.9 10.6 14.6 48.4 20 0 46.5 7.7 13.4 47.4 14 0.1 53.1 10.8 17.0 52.3 16 0.1 10.2 16.1 51.9 50.7 18 0.1 50.1 10.0 11.7 48.9 20 0.1 8.6 9.5 47.9 46.1 Bagasse 14 0 49.9 16.6 16.5 50.2 16 0 13.3 13.3 48.7 49.0 18 0 12.3 11.2 47.4 46.9 20 0 10.0 9.8 46.4 44.9 14 0.1 17.4 15.0 51.0 50.3 16 0.1 12.1 49.4 14.7 49.7 18 0.1 12.7 10.7 48.0 46.9 20 0.1 9.0 47.1 10.8 44.1

(fibre length/fibre diameter) positively affects paper properties. As shown in Table 1, both raw materials had similar slenderness ratios (59 vs. 64) that were comparable to lemon grass (66.9) and sofia grass (59.2). Generally, it is considered that if the slenderness ratio of a fibre is less than 70, the resulting pulp will have poor strength [31]. Small-scale pulping

Pulping of kash and bagasse was carried out by KOH, KOH-AQ, soda, and NaOH-AQ processes with varying alkali charges, with the results given in Table 2. It was found that 14% alkali charge as NaOH on dry fibre was required to produce a bleachable-grade pulp for both kash and bagasse, which was a relatively low amount of alkali compared with wood pulping. This low chemical usage is due to the low lignin content and porous struc-

Fig. 2 - Pulp yield vs. kappa relationship of kash in different processes.

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ture of these crops. Both alkalis showed almost similar behaviour when delignifying kash and bagasse. The kappa number of bagasse decreased from 16.6 to 10.0 with an increase in KOH charge from 14% to 20% (as NaOH), whereas the kappa number of kash decreased from 12.5 to 7.7. The slightly lower kappa number of kash pulp can be attributed to its lower lignin content (Table 1). In our earlier study, formic acid treatment at boiling temperature for 120 min followed by peroxyformic acid treatment at 80oC for 120 min produced a kash pulp yield of 46.2% with a lignin content of 2.5% [12]. As shown in Table 2, AQ is advantageous in terms of delignification. These results are in agreement with those reported for soda-AQ pulping of wood and nonwood fibres [11,31–33]. Figures 2 and 3 show the pulp yield and kappa number relationship of kash and bagasse pulps. In the case of kash

Fig. 3 - Pulp yield vs. kappa relationship of bagasse in different processes.

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pulp, the KOH and KOH-AQ processes showed higher pulp yield at any kappa number than the corresponding NaOH and NaOH-AQ processes. However, in the case of bagasse, the NaOH-AQ process showed slightly better pulp yield at kappa numbers higher than 10, but at lower kappa numbers, all pulp yields were almost equal for all processes (Fig. 3). At kappa number 10, pulp yield from kash in the KOH-AQ process was 50%, which was 2% higher than in the KOH process. For bagasse, the pulp yield was close to 47% at kappa number 11 in both KOH-AQ and NaOH-AQ processes; this yield was higher than in the corresponding KOH and NaOH processes. From the above discussion, it can be seen that kash is a slightly better raw material than bagasse in terms of pulp yield and kappa number and that the KOH-AQ process showed better results than the other processes. Pulp evaluation

To evaluate the various pulps, kash and bagasse were pulped in a 5-L capacity digester with a 16% alkali charge (as NaOH) for 120 min at 150°C. The results were different from those in small-scale pulping. In the KOH process, pulp yields were 48.6% and 46.3% at kappa numbers of 7.4 and 12.3 for kash and bagasse respectively (Table 3). As expected, delignification was accelerated by AQ addition to alkali liquor [32]. AQ addition increased pulp yield by 0.3% for kash and 2.8% for bagasse. AQ in soda liquor in A. auriculiformis pulping increased pulping selectivity and reduced alkali consumption by 4%, achieving similar pulp yield and kappa number [33]. At small scale, slightly higher pulp yield and kappa number were observed due to improper mixing of the cooking liquor with the raw material. Slightly improved pulp yield and kappa number were obtained in the KOH process than in the NaOH process. These pulps were beaten in a PFI mill to different °SR values, and handsheets were prepared to evaluate papermaking properties, with the results shown in Table 3 at °SR 40 by extrapolation. Bagasse pulp showed slightly better tensile index and

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Papermaking properties of KOH and NaOH pulp from kash and bagasse.

TABLE 3 Raw material

Process

Kash

NaOH NaOH-AQ KOH KOH-AQ NaOH NaOH-AQ KOH KOH-AQ

Bagasse

Pulp yield (%) 48.1 48.6 48.6 48.9 46.6 49.5 46.3 49.1

Kappa number 11.0 8.1 7.4 7.3 11.0 10.6 12.3 11.0

lower tear index than kash pulp. Insignificant differences were observed between the KOH and NaOH processes. The tensile index and tear index of S. spontaneum pulp from the KOH-AQ process were 65.2 N.m/g and 8.9 mN.m2/g respectively. These results are better than for the mixed hardwood furnish presently used in Bangladesh [34]. Bleaching

Kash and bagasse pulps were bleached by D0EpD1 bleaching sequences, with the results shown in Table 4. Kash pulp showed better bleachability than bagasse pulp. With a consumption of 25k ClO2/ton of pulp, KOH-AQ pulp brightness reached 86.6% for kash and 84.0% for bagasse. Although the unbleached brightness of NaOH-AQ/KOH-AQ pulp was lower,

Tensile index (N.m/g) 65.3 64.3 64.7 65.2 70.6 71.9 67.0 69.9

Burst index (kPa.m2/g) 5.1 5.5 5.3 5.2 5.3 5.4 5.1 5.4

the final brightness was higher due to lower initial kappa number. Low kappa number represents low lignin content and easy pulp bleachability [35]. A lower PhOH concentration in residual lignin was suspected to cause lower bleachability. In the KOH-AQ process, pulp brightness was 86.6% for kash and 84.0% for bagasse. These pulps were beaten in a PFI mill to different °SR values, and handsheets were prepared to evaluate the papermaking properties of bleached pulps at °SR 40, with the results given in Table 4. KOH-AQ pulp from kash showed a tensile index of 62 N.m/g, which was 12.7% lower than the corresponding bagasse pulp. However, the tear index of kash pulp was higher than that of bagasse pulp due to its longer fibre length (Table 1). The viscosity of NaOH-AQ/KOH-AQ

Properties of bleached pulp from kash and bagasse.

TABLE 4 Raw material Process

Viscosity Tensile index Burst index Brightness (%) (N.m/g) (kPa.m2/g) Unbleached Bleached (mPa.s) 60.9 NaOH 17.7 4.9 31.0 82.0 NaOH-AQ 57.4 22.7 4.6 30.1 85.6 KOH 59.1 27.7 4.4 32.0 84.2 KOH-AQ 30.1 62.2 4.2 26.6 86.6 NaOH 16.1 65.4 5.2 31.9 81.0 NaOH-AQ 24.7 69.9 5.3 30.0 83.0 KOH 23.7 63.1 4.8 25.8 81.2 70.1 KOH-AQ 27.4 5.2 24.0 84.0

Kash

Bagasse

TABLE 5

Tear index (mN.m2/g) 9.4 8.7 9.3 8.9 6.9 6.8 6.2 5.6

Tear index (mN.m2/g) 7.4 8.7 9.0 8.1 6.8 6.5 6.0 5.6

Improvement of soil properties after applying black liquor.

Soil properties

Control soil

Texture Sand (%) Silt (%) Clay (%) pH Bulk Density (gm/cm3) Particle Density (gm/cm3) Organic Matter (%) CEC (cmol kg-1 soil) Total Nitrogen (%) Available P (µg/g soil) Available K (µg/g soil) Available S (µg/g soil)

Silty Loam 15.1 42.7 42.2 7.15 1.38 2.39 1.03 22.1 0.16 13.2 77.3 23.3

Pulping liquor added to soil (PL) Silty Loam 15.6 42.2 42.2 7.81 1.45 2.41 2.98 31.4 0.46 65.1 414.3 54.2

Recommended Recommended fertilizer fertilizer applied dose with pulping liquor on soil (RF) applied in soil (RF+PL) Silty Loam Silty Loam 15.4 15.5 42.5 42.2 42.3 42.1 7.37 7.67 1.34 1.43 2.37 2.44 1.13 2.13 23.78 26.78 0.78 0.81 216.3 237.2 445.3 458.43 231.4 245.6

CEC- Cation exchange capacity, P-Phosphorus, K-Potassium, S-Sulphur

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pulp was higher than the corresponding NaOH/KOH pulp. This result indicated that AQ in alkali liquor protects carbohydrates from alkaline degradation. Soil properties

As shown in Table 5, KOH pulping black liquor had no effect on texture, sand, silt, clay, pH bulk density, or particle size. However, organic matter content doubled with black liquor application. The black liquors contained organic C, which was mostly derived from polysaccharides and lignin in black liquor, which suggests that black liquor may have potential as a soil amendment. Table 5 shows that black liquor application increased plant nutrients. The cation exchange capacity (CEC) of soil was increased by 42% after black liquor application. Available K in PLapplied soil was increased to 414.3 Âľg/g soil from 77.3 Âľg/g soil in the control soil. Xiao [36] found that a satisfactory pulp as well as a high-value potassiumbased fertilizer could be obtained when sodium is replaced by potassium in Kraft pulping. Table 5 shows that nitrogen (N), phosphorus (P), and sulphur (S) contents in soil increased with soil amendment by black liquor, which was advantageous for plant growth.

CONCLUSIONS

The chemical characteristics of S. spontaneum and bagasse were similar, which suggested similar pulping behaviour of both raw materials. The KOH process showed similar or better delignification degree and

TABLE 6 Plant properties Plant weight (g/pot) Plant height (cm) Shoot dry weight (g/pot)

pulp yield compared with the NaOH process. AQ addition slightly improved delignification degree and pulping selectivity. Pulp yield from S. spontaneum was slightly higher than from bagasse. Bagasse pulp showed slightly better tensile index and lower tear index than the corresponding S.

Plant yield properties. Control Soil PL 45.4 123.45 15.8 36.45 6.78 17.87

RF 165.34 35.21 19.34

PL+RF 189.43 38.76 20.56

Yield of Red amaranthus

Table 6 shows the effect of KOH pulping black liquor on yield of Red amaranthus. Plant weight was increased to 123.45 g/ pot from 45.4 g/pot with black liquor application and was further increased to 189.43 g/pot by application of RF and black liquor. K in RF was replaced by K in black liquor. In addition to K, black liquor contained organics (Table 5), which improved soil quality and increased growth. Plant height and shoot weight were also increased by applying black liquor (Table 6). Shoot weight increased from 6.78 g/ pot to 17.87 g/pot by soil amendment with PL, whereas RF with PL increased shoot weight to 20.56 g/pot. Figure 4 shows evidence of good growth of Red amaranthus. Fig. 4 - Growth of Red amaranthus after applying KOH pulping black liquor.

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spontaneum pulp. Insignificant differences in papermaking properties were observed between the KOH and NaOH processes. The bleachability of S. spontaneum pulp was better than the corresponding bagasse pulp. KOH-based pulping black liquor improved soil quality and consequently increased plant yields.

10.

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Qi, K., “China Catches Up”, Pulp and Paper Int. 46(4):45-48 (2004). Huang, G., Zhang, C., Fang, Y.J., “Cleaner Production of Wheat Straw”, Process Eng. 2(6):547-52 (2002). Huang, G., Shi, J.X., Langrish, T.A., “NH4OH–KOH Pulping Mechanisms and Kinetics of Rice Straw”, Bioresource Technology, 98(6):1218-1223 (2007). Rainey, T.J., Doherty, W.O., Sharman, S.A., “A Comparison between Bagasse and Water Efficient Alternatives using KOH/AQ Pulping”, Appita Journal, 67(2):128-132 (2014). Chaudhary, G., Singh, L.K., Ghosh, S., “Alkaline Pretreatment Methods Followed by Acid Hydrolysis of Saccharum spontaneum for Bioethanol Production”, Bioresource Technology, 124:111-118 (2012). Kataria, R., Ghosh, S., “Saccharification of Kans Grass Using Enzyme Mixture from Trichoderma reesei for Bioethanol Production”, Bioresource Technology, 102(21):9970-9975 (2011). Scordia, D., Cosentino, S.L., Jeffries, T.W., “Second-Generation Bioethanol Production from Saccharum spontaneum L. ssp. aegyptiacum (Willd.) Hack”, Bioresource Technology, 101(14), 5358-5365 (2010). Chandel, A.K., Narasu, M.L., Chandrasekhar, G., Manikyam, A., Rao, L.V., “Use of Saccharum spontaneum (Wild Sugarcane) as Biomaterial for Cell Immobilization and Modulated Ethanol Production by Thermotolerant Saccharomyces cerevisiae VS 3”, Bioresource Technology, 100(8): 2404-2410 (2009). Guha, S.R.D., Mathur, G.M., Sharma, Y.K., “Production of Writing and Printing Papers from a Mixture of Grasses Growing in Mechanised Plantations of

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tent of Various Plant Materials and their Suitability for Paper Production”, Industrial Crops and Products, 19(3):245-254 (2004). 32. MacLeod, J.M., Fleming, B.I., Kubes, G.J., Bolker, H.I. “Strengths of KraftAQ and Soda-AQ Pulps: BleachableGrade Pulps”, Tappi J. 63(1):57 (1980). 33. Jahan, M.S., Haider, M.M., Rahman, M., Biswas, D., Misbahuddin, M., Mondal,

G.K., “Evaluation of Rubber Wood (Hevea brasiliensis) as a Raw Material for Kraft Pulping”, Nord. Pulp Pap. Res. J, 26(3):258-262 (2011). 34. Jahan, M.S., Sabina, R., Rubaiyat, A., “Alkaline Pulping and Bleaching of Acacia auriculiformis Grown in Bangladesh”, Turkish Journal of Agriculture and Forestry, 32(4): 339-347 (2008). 35. Gullichsen, J., Fogelholm, C., Papermak-

ing Science and Technology Book Series, 6: Chemical Pulping, TAPPI, B411, pp. 656-658 (2000). 36. Xiao, C., “Black Liquor from Crop Straw Pulping as a Potassium Source and Soil Amendment”, PhD dissertation, Washington State University, Pullman, Washington (2005).

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TROUBLESHOOTING A BLACK LIQUOR CONCENTRATOR SOLIDS CONTROL PROBLEM VIA MODELLING AND SIMULATION ABSTRACT

WEI REN*, BRUCE ALLISON In the Kraft recovery process, multiple-effect evaporators and concentrators are used to increase black liquor solids concentration for firing in the recovery boiler. Black liquor solids content strongly affects boiler thermal efficiency and steam production. Solids variability is a recurring problem that can cause mills to set conservative targets, thereby reducing profitability. One approach to minimizing solids variability is through improved process control. A new dynamic model for a concentrator system has been developed and subsequently used to troubleshoot a known solids variability problem in an operating mill. The model was developed based on first principles and includes the mill control system. It can capture the dominant process dynamics as well as disturbances that have a large impact on solids variability. Simulations were used to design and test solids control improvements that were then implemented in the mill. Process data illustrate clearly that the re-tuned controllers have reduced solids variability.

INTRODUCTION

In the Kraft recovery process, multiple-effect evaporators are used to increase black liquor solids concentration so that the solids can be burned effectively in the recovery boiler. The boiler burns organic matter in the black liquor for steam and power generation, and therefore black liquor quality strongly affects boiler operation [1,2]. The combustion properties of black liquor depend on many factors, including wood species, digester conditions, and chemical addition [3]. For example, hardwood pulping generally generates less black liquor solids than softwood. Black liquor solids variability is a recurring problem at many pulp mills and sometimes causes mills to set conservative targets for as-fired black liquor solids to prevent boiler upset. Minimizing solids variability through improved process control can lead to a more consistent liquor feed rate to the recovery boiler and provide the possibility of increasing solids target level. For a typical 1,000 tonne per day mill, a 1% increase in solids target is equal to a gain of $150,000

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per year. In addition, black liquor viscosity is strongly affected by solids concentration, which in turn affects liquor spray pattern and droplet size [4]. Hence, improving solids control also reduces a source of viscosity variability. These benefits are especially important for mills that run to a high solids target. However, to improve solids control, it is necessary to understand the process dynamics of black liquor processing in the evaporators and concentrators. This can be done through modelling using first principles and process data. Many generalized steady-state mathematical and simulation models aimed at optimizing steam use and reducing energy costs have been developed [5–8], but these do not include the dynamics needed to characterize control applications. Dynamic modelling was used to develop and test a proposed control strategy for an evaporation plant under construction [9]. The authors concluded that dynamic simulation can be very useful in determining the feasibility of candidate control systems,

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WEI REN

Research Engineer, FPInnovations, Vancouver, BC Canada *Contact: Wei.Ren@fpinnovations.ca

BRUCE ALLISON

Principle Research Engineer and Research Leader, FPInnovations Vancouver, BC Canada


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but unfortunately their study provided limited validation against process data. Some research has been done on modelling evaporator systems specifically for advanced control studies (model predictive control or MPC) [10,11]; however, these studies were either theoretical or done on pilot scale equipment only. This paper proposes a new simulation model for a concentrator system in an operating Kraft mill with known solids consistency problems. The purpose of the model is to improve the current control system and identify possible reasons for continuous solids deviations from controller set-points as shown in process data. The paper provides a description of the mill’s concentrator system and the implemented control strategy. The assumptions, material and energy balances, and model parameters are explained. Simulation results are validated against mill operating data. Improvements to the model and possible causes of solids variability are explored. Finally, the paper investigates possible approaches to implement practical solutions for improving solids control in the concentrators. PROCESS DESCRIPTION

In the Kraft recovery cycle, a concentrator system is used to achieve a further increase in black liquor solids concentration after the evaporators. The concentrator system typically receives a black liquor feed at

roughly 57% solids by weight and produces black liquor at 75 wt% solids. The concentrator system studied in this paper is shown in Fig. 1. The system consists of two concentrator stages (effects). They are both platetype falling-film concentrators, with black liquor forming a falling film on the outside and steam providing the driving force for heat transfer inside the plates. The first concentrator effect is divided into two sections (“A” and “B”) and has separate liquor circulation and steam systems. Black liquor is fed into the second effect from the intermediate tank, and steam is fed into the first effect. Liquor and steam flow counter-currently, and the reduction in temperature and pressure enables steam that was saturated in earlier effects to be used for evaporation in later effects to increase the overall energy efficiency (steam economy) of the process. The concentrators have a control system, also shown in Fig. 1, consisting of solids (S), steam pressure (P), and black liquor (BL) level (L) controllers. The solids controller is located at the outlet of effect 1A and is based on either a calculated value or the reading from a refractometer. The solids set-point is manually set by the operators, and solids content is maintained by changing the steam pressure controller set-points. The steam flowrates are then varied to maintain the steam pressures. In addition, each effect has a BL level controller, which maintains a manually set

Fig. 1 - Simplified schematic of the concentrator system and its associated control strategy.

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level set-point by changing the black liquor outlet flowrate to the downstream effect. Because black liquor solids concentration is affected by the complex interaction of process and control dynamics, development of a dynamic model becomes a useful tool to understand the system and to improve the control design. MODEL DEVELOPMENT

Each effect is modeled by a heat-transfer surface and liquor reservoir in a recirculation loop, as shown in Fig. 2. The black liquor reservoir at the bottom of each effect is assumed to act as a continuously stirred tank. The plate heating elements act as the heat-exchange surface between black liquor and steam. Black liquor is circulated around the system through a recirculation flow. Unsteady-state material and energy balances result in the following set of ordinary differential equations for the liquor reservoir level L, the solids concentration X, and the liquor temperature T: (1)

(2)

Fig. 2 - Schematic of material and energy flow for a single concentrator effect.

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(3) The variables and parameters are black liquor volumetric flow rate F, reservoir cross-sectional area A, density ρ, and heat capacity Cp. The subscripts in, 1, and 2 refer to concentrator inlet flow and recirculation flow to and from the fallingfilm plates respectively. The volume of the continuous stirred tank in Eqs. (2) and (3) is divided by 3 due to the conical shape of the black liquor reservoir at the bottom of each effect. The heat-transfer surface of the concentrator in Fig. 2 is shown in expanded form in Fig. 3. The steam-side block models the steam temperature, Ts (and pressure, Ps, assuming saturated steam) and the resulting rate of heat transfer, q, from the steam to the liquor. The steam mass flow rate, Ms, and the liquor temperature, T1, are inputs to this block. The heat-transfer rate is a function of the heat-transfer area, As, the temperature difference between the steam and the liquor, and the overall heat transfer coefficient, Us, according to Eq. (4): (4) The temperature (and pressure) of steam occupying the vapour space on the steam side of the heat exchanger are determined by a balance on the mass of steam, as shown in Eq. (5), where Vs and ρs are the volume and density of steam respectively. Equation (6) is used to calculate the condensate mass flow rate, Mc, using q and the difference in enthalpies (H) between the steam and the condensate:

(5) (6) The correlations used for the properties of saturated steam (Ps, Hw, Hs, and ρs) as a function of temperature are shown in the Appendix [12]. In essence, Eqs. (4)–(6) form a set of non-linear ordinary differential equations for the unknown steam temperature. The liquor-side block in Fig. 3 models the liquor side of the heat-transfer surface. Stream 1 (F1, T1, X1, ρ1) is known from the material balance around the liquor reservoir discussed earlier. The total heat input, q, is known from the solution to the steam side, as just discussed. Finally, the dome pressure, Pd, is supplied by a solution to the steam-side equations of the upstream effect. Stream 2 (F2, T2, X2, ρ2) and total vapour (Mvap) are determined by material and energy balances that result in the following set of non-linear algebraic equations (7)–(10). Correlations for black liquor density (ρ), boiling point rise (fbpr), and heat capacity (Cp) are also shown in the Appendix [1,13]. In addition, Hvap is the enthalpy of evaporation at dome pressure, and ρw is the water density.

Fig. 3 - Model for the concentrator heat-transfer surface.

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(7) (8) (9) (10)

Equations (7)–(10) are solved according to the following procedure: 1. Start with an initial guess for X2. 2. Solve for T2 using the boiling point correlation in Eq. (7). 3. Solve for the densities and heat capacities of streams 1 and 2 and the enthalpy of evaporation at dome pressures using the appropriate correlations in the Appendix. 4. Solve Eqs. (8)–(10) for Mvap, F2, and X2 respectively. 5. Repeat steps 2–4 until X2 converges. Although there is no guarantee that this procedure is globally convergent for any initial guess, it is possible to bracket the solution, and therefore the initial guess, within a feasible region. The lower bound of this region is provided by the inlet solids content X1. The upper bound is easily calculated by assuming that all of heat input (q) goes into evaporation. In the simulations in this study, the procedure never failed to converge, and the solution was always within the feasible region when the initial guess was also within this region. In addition to the process dynamics of the concentrator system, the current control strategy is also implemented in the model. All controllers use the proportional-integral algorithm (PI control) and therefore each requires a controller gain (Kc) and a reset time (Tr). These tuning parameters are used to adjust the controller response when a difference (or error) occurs between the measured value and the desired set-point value. A single-stage model was first developed using mill operating data and controller tuning parameters. The model was then expanded to cover a three-stage concentrator system, as shown in Fig. 4. A list of the process and controller parameters implemented in the initial model can be found in Table 1. The liquor reservoir cross-sectional areas, overall heat-transfer areas, and recirculated flowrates are drawn from mill operating manuals. The overall heat-transfer coefficient for each effect was determined by simulation using

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Fig. 4 - Complete model for three-effect concentrator system in MATLAB.

process data and Eqs. (4)–(6). RESULTS

Simulation results based on the developed model were validated against process data collected from the mill. The collected data included solids concentration (in %), black liquor temperature (in °C), steam pressure (in psig), and black liquor reservoir level (in %) for all three effects. The simulation inputs are the second-effect inlet black liquor flowrate, solids, and temperature and

the 1A and 1B steam pressure set-points. For a typical data set, eight hours of data were collected. Figure 5 compares the predicted results with mill data. The mill process data clearly illustrate process variability during normal operation. Oscillatory behaviour is apparent for all four variables. The model predicts some of the variability for solids, but oscillation peaks do not reach the same magnitude as those in the process data. In addition, the peaks do not always match up, which means that the model might

TABLE 1 Initial process and controller tuning parameters. Concentrator Effect 1A Parameter Liquor reservoir area Level controller gain (Kc) Level controller reset time (Tr) Concentrator Effect 1B Parameter Liquor reservoir area Level controller gain (Kc) Level controller reset time (Tr) Concentrator effect 2 Parameter Liquor reservoir area Level controller gain (Kc) Level controller reset time (Tr) Solids controller Parameter Solids controller gain (Kc) 1A steam controller gain (Kc) 1B steam controller gain (Kc)

Value 9.34 m2 3.1 9.0

Parameter Overall heat-transfer coefficient Overall heat-transfer area Recirculation flow rate

Value 417 W/m2/K 2569 m2 27 m3/min

Value 9.34 m2 2.8 45.0

Parameter Overall heat-transfer coefficient Overall heat-transfer area Recirculation flow rate

Value 333 W/m2/K 2569 m2 27 m3/min

Value 15.34 m2 1.3 10.0

Parameter Overall heat-transfer coefficient Overall heat-transfer area Recirculation flow rate

Value 700 W/m2/K 2648 m2 24 m3/min

Value 0.33 0.5 0.5

Parameter Solids controller reset time (Tr) 1A steam controller reset time (Tr) 1B steam controller reset time (Tr)

Value 30 min 2 min 1 min

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lack one or more dynamic elements or disturbances. Because the solids controller is based on 1A solids, future validation results will omit solids for effects 1B and 2. In addition, the solids concentration is a function of black liquor temperature and dome pressure (which is relatively constant), and therefore variability in temperature closely mirrors variability in solids. Hence, validation on temperature will be omitted in the future as well. The simulated steam pressure validates well with process data, indicating that the difference in solids variability between the simulation and process data is not due to changes in steam pressure. Future validation results will include steam pressure only for the 1A effect because it is representative of the three effects. Finally and most interestingly, the model predicts a relatively stable level for all three effects, whereas the process data show a high degree of oscillation. The reservoir level variability is most noticeable in the 1B effect and will be used in future validations as an indication of the model’s ability to predict level. Figure 6 shows the same validation results as Fig. 5, but for a subset of variables (1A solids concentration, 1A steam pressure, and 1B level only) and during a period of high process variability. The inability to predict level variability in the process data shows that additional disturbances exist in the process, but were not captured in the model. The data show a relatively constant inlet flowrate, meaning that variability in level must have another cause. In this context, the level measurement was examined. Each effect uses a differential pressure level measurement technique to determine level, as shown in Fig. 7. Each effect is essentially a sealed vessel with a gas blanket on top of the contained liquor. The pressure of the gas (dome pressure) adds to the hydrostatic pressure created by the water column of the liquor. This makes it difficult to obtain an accurate level measurement using a conventional pressure gauge. A differential pressure gauge measures the difference between gas pressure and total pressure, which is translated into a true liquid level reading. Differential pressure

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Fig. 5 - Preliminary model validation of solids concentration, temperature, steam pressure, and level for all three effects.

transmitters typically have two inlet ports, a high-pressure connection that measures the pressure at the bottom of the liquor reservoir, and a low-pressure connection that measures the pressure of the gas phase. The latter is often referred to as the reference leg. The reference leg must be maintained; otherwise, plugging can occur and introduce errors into the level measurement. In other words, dome

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pressure variability will show up as false level variability when reference leg compensation fails. An additional module that simulates failed pressure compensation was added to the model. The simulation shown in Fig. 6 was repeated, with the results presented in Fig. 8. The results show that the model can now capture the oscillatory behaviour of level and also produce a better

prediction of solids variability. The new validation demonstrates how level variability can greatly affect the whole process. In other words, the model can provide a better prediction of concentrator solids when level oscillations are accurately predicted. To see how this failed level measurement affects the process dynamics, Fig. 9 shows a unit step change in the output of the solids controller when the level measurement is functioning properly and when it is not. When the level measurement is functioning normally, the solids begin to increase immediately when the steam pressure increases, which is the ideal response. On the other hand, when the level measurement fails, the solids actually decrease before finally increasing for the same change in steam pressure. This type of process response, i.e., one that initially goes the wrong way, is very much like dead time in that the delay in process response tends to destabilize the closed-loop system. This likely explains the poor control of black liquor solids in the concentrators. A physical explanation for this result is provided in Fig. 10. The path highlighted in red represents the normal solids feedback control loop, where a change in solids due to a system disturbance causes the solids controller to manipulate the pressure and, in turn, the steam flowrate into the first effect. For example, a decrease in solids leads to an increase in steam pressure so that the solids can be brought back to its set-point. This is the desirable type of negative feedback that occurs when the output of a system is fed back in a manner that tends to reduce fluctuations in the output. However, as illustrated by the path highlighted in blue, when reference leg compensation fails, an additional feedback loop exists in the process. In this case, when the solids decrease, the increase in steam pressure increases the total evaporated vapour, which then causes the dome pressure to increase. The resulting false increase in level will cause the level controller to increase the black liquor flowrate from effect 1B to 1A. Adding a surge of black liquor at lower solids causes the solids in effect 1A to decrease even further. This is a positive-feedback loop that

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Fig. 6 - Summary of preliminary model validation.

increases the magnitude of the perturbation, resulting in the wrong-way response shown in Fig. 9. Fortunately, the level controller is tuned in such a way that the effect of the positive-feedback path eventually dies out and the solids eventually respond as expected. Finally, it is important to point out that this is only one of a number of possible explanations for the observed level variability and that there is no way to confirm through data alone that this explanation is the correct one. However, including this additional interaction provides a mechanism to describe the process dynamics more fully, therefore making it possible to use simulation to investigate options for improving the control design.

Fig. 7 - Level measurement and control in each effect.

Several options are available to make the control design more robust: (i) re-tune the 1B level controller, (ii) re-tune the steam pressure controllers, or (iii) re-tune the solids controller. The following figures show the simulated effect of these three options. Two perturbations are entered in each simulation: the first is a flowrate (production) increase at time 100 minutes, and the second is a solids set-point decrease at time 500 minutes. Retuning the 1B level controller (Fig. 11) significantly reduces the oscillatory behaviour in the process, but the response is still somewhat under damped. Retuning the pressure controllers alone (Fig. 12) has a similar effect, although the response is a little more stable. Because solids and steam pressure are

Fig. 8 - Validation of updated model with the addition of level interaction.

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under cascade control, re-tuning the solids controller along with the steam pressure control shows the most stable controller response (Fig. 13). The proposed new tuning parameters for the pressure and solids controllers were implemented at the mill. Figures 14 and 15 show mill process data for solids and steam pressure under similar operating conditions with previous and new tuning parameters respectively. The results illustrate clearly that the re-tuned controllers have reduced both solids and steam pressure oscillations. Deviations from set-point have also been substantially reduced. These results show the effectiveness of using modelling and simulation to improve process control by optimizing

Fig. 9 - Open-loop simulation of solids concentration for a step change in steam pressure set-point.

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Fig. 10 - Normal solids control loop in red and false level dynamics in blue.

Fig. 11 - Re-tuning impact on effect 1B level controller.

Fig. 12 - Re-tuning impact on effect 1A and effect 1B steam pressure controllers.

Fig. 13 - Re-tuning impact on effect 1A and 1B steam pressure controllers and solids controller.

Fig. 14 - Mill process data for solids and steam pressure with previous tunings.

Fig. 15 - Mill process data for solids and steam pressure with new tunings.

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existing mill controllers.

REFERENCES 1.

CONCLUSIONS

This report presents a new dynamic model for a concentrator system that was subsequently used to troubleshoot a solids variability problem. Model predictions were validated against process data. The results show that the model can capture the dominant process dynamics in the system, although not all variability present in the mill was properly predicted. The model had to be modified to include the possibility of false level disturbances that can have a large impact on solids variability. This report illustrates the value of process simulation and modelling as a basis for identifying potential process disturbances and improving control strategies. More specifically, the simulations were used to design and test control improvements that were directly implemented in the mill.

2.

3.

4.

5.

6.

Frederick, W.J., Noopha, T., and Hupa, M., “Combustion Behavior of Black Liquor at High Solids Firing”, TAPPI Journal, 74(12):163-170 (1991). Karvinen, R., Hyoty, P., and Siiskonen, P., “The Effect of Dry Solids Content on Recovery Boiler Furnace Behavior”, TAPPI Journal, 74(12):171-177 (1991). Reeve, D.W., “The Kraft Recovery Cycle”, TAPPI Kraft Recovery Operations Short Course, St. Petersburg, FL, USA (2000). McCabe, F.D., Mott, D., Savoy, D., and Tran, H., “Controlling Black Liquor Viscosity to Improve Recovery Boiler Performance”, International Chemical Recovery Conference, Quebec City, QC, Canada (2007). Shah, D.J. and Bhagchandani, C.G., “Design, Modelling, and Simulation of Multiple Effect Evaporators”, International Journal of Scientific Engineering and Technology, 1(3):1-5 (2012). Khanam, S. and Mohanty, B., “Energy Reduction Schemes for Multiple Effect Evaporator System”, Journal of Applied Energy, 87(4):1102-1111 (2010).

7.

8.

9.

10.

11.

12. 13.

Olsson M.R., “Simulation of Evaporation Plants in Kraft Pulp Mills”, Chalmers University of Technology, Sweden (2009). Bhargava, R., Khanam, S., Mohanty, B., and Ray, A.K., “Simulation of Flat Falling Film Evaporator System for Concentration of Black Liquor”, Computers & Chemical Engineering 32(12):3213-3223 (2008). Dumont, G.A. and Legault, N.D., “Dynamic Simulation of a Black Liquor Evaporation Plant”, Pulp and Paper Research Institute of Canada, Pointe Claire, QC, Canada (1983). Stefanov, Z.I., “Fundamental Modeling and Control of Falling Film Evaporators”, Texas Tech University, Lubbock, Texas, USA (2014). Russell, N.T., “Dynamic Modelling of a Falling-Film Evaporator for Model Predictive Control”, Massey University, New Zealand (1997). Felder, R.M. and Rousseau, R.W., Elementary Principles of Chemical Processes, Wiley, Canada (1978). Gullichsen, J. and Fogelhom, C.J., Chemical Pulping, Fapet Oy, Finland (1999).

APPENDIX

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Building Buildingfor forthe the and Paper NewPulp Pulp and Paper Community Community

FOR THE ADVANCEMENT OF THE FOREST INDUSTRY

J-FOR Journal of Science & Technology for Forest Products and Processes contains papers which are the property of the Pulp and Paper Technical Association of Canada (PAPTAC). Papers may not be reprinted or reproduced without permission. These papers have been peer reviewed and approved for publication by the Editorial staff. J-FOR is published bi-monthly by PAPTAC, 740 Notre Dame West, Suite 1070, Montreal, QC, Canada H3C 3X6, to which all general correspondence should be addressed. J-FOR Journal of Science & Technology for Forest Products and Processes is indexed and/ or abstracted with CAS (Chemical Abstracts Service, a division of the American Chemical Society), Thomson Reuters, and ProQuest. Vol. 6 subscriptions for a printed copy and on-line access are: Canada (includes all applicable taxes) – $850.00 Cdn; USA – $850.00 Cdn; Overseas – $875.00 Cdn. No part of this Journal may be reproduced, stored in a retrieval system or transmitted, in any form or by any means, without the prior written permission of PAPTAC or, in case of photocopying or other reprographic copying, a licence from Access Copyright (the Canadian Copyright Licensing Agency), 1 Yonge Street, Ste. 1900, Toronto, ON, Canada M5E 1E5. ISSN 1927-6311 (Print) ISSN 1927-632X (Online) Printed in Canada

Some of the photos in the Journal provided courtesy of FPAC.

J-FOR A PAPTAC JOURNAL

JOURNAL OF SCIENCE & TECHNOLOGY FOR FOREST PRODUCTS AND PROCESSES


CALL FOR PAPERS Be part of this emerging global forest community publication

BUILDING FOR THE NEW PULP & PAPER COMMUNITY

J-FOR

Journal of Science & Technology for Forest Products and Processes A PAPTAC JOURNAL

J-FOR is PAPTAC's preeminent flagship journal, and publishes peer-reviewed high-quality articles that

address technological and scientific issues that are critical to the forest industry.

J-FOR emphasizes a unique balance between papers that address traditional technology areas, as well as emerging technology areas as our industry transforms to new business models.

These target areas are supported by a distinguished and international Editorial Board comprised of leading experts in the field. Authors are welcome to submit their papers to J-FOR Traditional Technology and Scientific Target Areas: • Pulping, bleaching and papermaking fundamentals, processes and technologies • Energy and chemical recovery fundamentals, processes and technologies • Recycled fibre and recycling technology • Development of sensors, analytical methods and process control logics • Mill water and energy usages and optimization • Environmental concerns and their mitigation

Emerging Technology and Scientific Target Areas: • Emerging forest-based products and their chains of added value • Fundamentals of converting forest-based biomass into biofuels and other bioproducts • Nanotechnology and other high added-value processes • Development of chemical, biochemical and thermochemical processes for the forestry industry • Integrating emerging and sustainable processes into the pulp and paper industry • Harvesting and procurement of forest and other biomass feedstocks Published by:

J-FOR is published on a bi-monthly basis and distributed in printed format to corporate subscribers and libraries in over 30 countries. J-FOR is also available on-line in an open access publication format to maximize author impact and visibility. For further information, please visit www.paptac.ca or contact PAPTAC at 514-392-0265/tech@paptac.ca.

Publishing establishes ownerships of ideas, enhances professional reputation and opens networking opportunities with colleagues.


OXAMINE FOR INFLUENT: ®

UNMATCHED PERFORMANCE

Oxamine for influent is more stable,

so it works harder longer than bleach, chlorine gas and bromide treatments to control microbiological activity and save you money. You may also know that it has less impact on the environment. But did you know that the Oxamine microbicide program comes with proprietary feed equipment designed for industry-leading safety? It’s the only technology on the market with all these advanced safety features.

© 2016 Buckman Laboratories International, Inc. All rights reserved.

UNMATCHED SAFETY • LEAK

DETECTION

• A BUILT-IN SEPARATOR

to keep active ingredients apart in the case of a line break or other issue

• AUTOMATIC FLUSHING

in case power is lost

• REGULAR INSPECTION

by Buckman personnel to ensure efficient, safe operation

Protect your equipment, your people, the environment and the bottom line. Contact your Buckman representative or visit buckman.com, and see just how easy it is to switch to Oxamine.

Preview of PaperWeek 2017 / J-FOR+ Vol.6 No.1  

J-FOR+ Issue 1 Volume 6, including a preview of PaperWeek Canada 2017 and Montreal BIOFOR International Conferences