Open meeting at 9:00 AM Tuesday, 2 May 2000 by chairman Richard Presley

The meeting was opened with a statement that this meeting would be held within compliance of the TAPPI Anti-Trust policy.

The floor was opened for each of us to make our own introductions; name, corporate or institution affiliations, and anything speculated about what that affiliation’s name might be in the near future due to the continuing saga of paper industry merger mania.

The agenda was quickly reviewed for the two-day meeting.

Tuesday

O₂ delig systems

ClO₂ generation systems

Wednesday

Mill Operations discussions

TAPPI Update: report by Eric Fletty

Host mill description and tour

The minutes of this meeting follow the above outline. There is a record of those in attendance at the end.

The purpose of the TAPPI Pulp Bleaching Committee is to organise and disseminate the technical information regarding bleaching of pulp. This is a volunteer effort, i.e. the officers aren’t paid to organise these meetings.

Richard Presley is the chairman and Wayne Bucher is the vice-chairman. Bob Packwood is the secretary.

Two subcommittees are presently in place, although our charter allows for more.

Steve Legge co-ordinates the Operations subcommittee (present operations issues)

Pete Gleadow co-ordinates the Minimum Effluent subcommittee (including R&D)

For this meeting, special thanks go to Chris Kanters who volunteered to assist with collecting the meeting fees and Barbara van Lierop for assisting with capturing notes during mill operations discussion.

How the committee functions:

Meetings are twice a year, spring with mill visit and in the fall just before the Pulping Conference

Excused absence granted with a simple notification prior to the meeting of not being able to attend. Involvement is required: Pick a subcommittee and speak up. Help with the fall pulping conference or one of the short courses we sponsor.

Major activities this committee sponsors include:

* IPBC: International Pulp Bleaching Conference (held every two years)

* TAPPI Pulping Conference, all bleaching sessions, roundtables, etc.

* TAPPI Bleaching Short Course

* Symposium on Minimising Bleaching Effluent

Wayne Bucher solicited assistance with the bleaching sessions for the Pulping Conference that will be in Boston in November this year. Session moderators will be selected from volunteers, and there are still ways to be involved as a moderator for a regular session, an interactive session, or a breakfast (mill operations) roundtable.

Operations subcommittee; report by Steve Legge

BP Operations Short Course was just held with good attendance. For the next two years, the dates and sites have been selected. These are April 17-20, 2001 at the Crown Plaza, Hilton Head SC, and March 25-28, 2002. Doug Reeve leads this short course, and has done an excellent job with this topic. We would like to see this continue however, maybe to consider other locations besides Gulf Shores and Hilton Head, maybe on the US west coast or in BC. Another suggestion is to have an audit committee of maybe 5 members to attend (free admission) and review the class for suggested changes.

Technical Information Pages, exchange within committees, how to get proper review for approval and then distribution. Eric Fletty (our TAPPI contact) will assist with this. This can proceed by closing the task with a closing form, and then TAPPI will post on the website for access. The review and posting process is being streamlined and is in flux itself, however, Eric will help with any questions. The e-mail list with distribution to all committee members seems to be working adequately and will be used to notify when TAPPI is posting items to the web page regarding pulp bleaching committee activities.

Bleaching designations need to be reviewed. A suggestion has been made that Barbara van Lierop will coordinate with PAPTEC and then lead discussion at our committee’s fall meeting in Boston, with the objective of having one method agreed upon at the close of the fall meeting in Boston. It was questioned if this was realistic, given the history of this topic, however, we all realise this is only a guideline to establish a common short-hand language.

An existing task assignment CA # 960606.02, Controls for O₂ delign, has been approved by TAPPI. Bill Miller will revise the survey (make it shorter) prior to issuing to the US mills.

Two new committee task assignments submitted.

1. Impacts of O₂ delig on recovery cycle and impact of pulp washing efficiency on bleaching. TAPPI Note: 000606.01

2. What technologies are US mills using for bleaching today? Jeff Zierdt has volunteered to organise this effort to survey mills represented within the committee only. Anticipate output being a presentation at a pulping conference to open a round table discussion about sequences. TAPPI Note: CA number is 000606.02

Subcommittee Report: Bleach Effluent Minimisation and future bleaching technologies. By chairman Peter Gleadow:

This subcommittee focuses on the issues that are presently not common practice in the industry, i.e., the future. This includes research topics for present operating problems as well as new chemistries. Some of the topics discussed within this subcommittee include:

* Polysulfide pulping and its impact on bleaching and final pulp properties.

* Scale formation and scale management

* New technology and equipment development

* Reductions in mill water use

* AOX reduction

During the break-out discussion time, the role of this subcommittee regarding research was discussed. Three key perspectives surfaced:

Increasingly pulp and paper products, equipment, chemicals and services are seen as commodities, and there has been a general reduction in R & D in the industry. There is a need to bring together academics/institutional research, operating companies and supplier companies, and governments with respect to research directions, funding, and co-ordination. The European model was seen as quite powerful in this respect.

Committee mechanisms to disseminate information and develop needs include technical conference sessions, short courses and interactive round tables.

Current activities of this subcommittee include:

* Closed-cycle short course – Tony Johnson, likely in fall, 2001

The old EB Eddy mill at Espanola, ON has a Polysulfide AQ system in operation now. They have been in continuous operation since starting last November with about 550 tons/day pulp capacity. They have increased mill capacity about 40 t/d with this effort, from combined benefits of improved yield, reduced load to recovery boiler, etc. This pulp is bleached partly with ozone. This is the PAPRILOX system, with formation of polysulphide in a causticizer, and the Manganese Dioxide catalyst recirculates in the lime system. The level of catalyst recirculating is about 4% on kiln product and 2% on mud.

Paprican has published data, at the PAPTAC meeting, Jan 2000, on bleached yield comparisons with and without oxygen delignification. With oxygen delignification from 40 or 30 kappa followed by 5 stage DEoDED bleaching on black spruce showed slightly higher yields (0.3% and 0.5% respectively) than DEoDED bleaching without O₂ from the same kappas. These yield differences were however not statistically different. A full paper describing the yield differences on a variety of pulps (PS, PS-AQ, and Kraft) is to be presented in Halifax at IPBC 2000.

Peter Gleadow added that several oxygen delignification systems have been installed to replace the typical EO stage within the bleach plant. These are two stage systems that save ClO₂ as economically viable projects without changes to pulp washing, however washing limitations is likely to be their limiting factor.

International Pulp Bleaching Conference in Halifax, report by Tom McDonough. This will be held 27-30 June in Halifax, Nova Scotia.

Dave Thirealt of Pope and Talbot at Halsey, Oregon discussed briefly their O₂ system, installed in 1993. They run campaigns alternating Douglas fir chips and mixed sawdust. Cooking is in M&D digesters with very short retention time, followed by 3 stages of vacuum washers. Slotted screens (0.014") are followed by the decker and the O₂ system. MgSO4 is added first. A custom-built system mixes O2 gas and steam with the pulp prior to going through two Ahlmixers, which are separated by about 2.5 minutes. They add typically 2% alkali and 2.2% oxygen, ratio controlled from the alkali charge. The reactor pressure control valve is at the blow tank with a back-pressure surge chamber inside the blow tank. This arrangement has avoided shaking and hammering of the blowline, a problem typical of many installations. Washing is with two wash presses, 0.9 meter diameter by 4.5 meter rolls. Pulp typically goes to bleach plant via the low consistency stock chest, but can be diverted to a brown HD.

Control is with a kappa analyser system. Pulmac wet zero span tensile is used to monitor pulp strength through the process.

Normal operation is 625 t/d with typical delignification rate of 45% on K No. Data was presented graphically on the operation with correlation between several parameters.

Ken Kendall of Weyerhaeuser at Longview, WA described their single stage O₂ delig system, now in operation for five years. They add either caustic or oxidised white liquor with a kappa analyser control system. Fibre length is also analysed, with three species run as separate grades. Softwood delig is 45% delign, and hardwood is about 40% delta kappa.

Operational problems include a physical movement at the top of the reactor, in a harmonic type sway. Adding more dilution at the top of the reactor eliminated this. Plugging of the stock line was a problem until a second valve was added at the top of the reactor. This valve is closed to facilitate flushing the blow line when shutting down.

Frank Steffes consultant to Valmet, talked about the present state of the science regarding oxygen delignification systems. He presented data from Pulp & Paper Canada magazine, Dec 1999. The survey data should not be taken as performance ability as some of the mills do not push the O2 system as hard as possible. This may be due to their objective of levelling the kappa into the bleaching system, or to optimise the balance between cooking, washing and oxygen delignification.

Normal maximum performances measured by delta kappa are:

Softwood Hardwood

Single stage systems 45 35

Mini- O₂ systems 5-30

Modern two stage systems 60-70 50

One primary reason for installing the newer technology is the improved yield of two stage O₂ compared to Kraft cooking yield. To take advantage of this, the cooking target kappa is raised, using the more selective chemistry of oxygen delignification to traditional kappa targets prior to bleaching.

Questions and comments from the floor about the general topic of oxygen delignification were diverse and spirited. Performance can be increased (% delta kappa) by increasing the oxygen driving force via raising the pressure rather than adding more oxygen gas. Ideally, to the raise the temperature of the pulp first (let the steam condense) prior to adding the oxygen, which should be preheated prior to mixing with the pulp stream. Heat load to the recovery boiler is probably insignificant, while the dry solids load is increased. The black liquor that is oxidised in the reactor is more of the temperature rise rather than the lignin on the pulp. Washing improvements are typically made when O₂ delig is added, with the washing alone making a significant change in the recovery load.

Peter Gleadow added some comments regarding mini-oxygen delignification systems to replace the typical EO stage within the bleach plant. This is a two-stage system can save ClO₂ with economically viable projects without changes to pulp washing, however that might be the limiting factor

Presentation: ClO₂ Generation Systems

Tom Rollbuhler of EKA Chemicals presented the basics of chlorine dioxide generation, with customisation is possible for site specific needs. Acid and reducing agent are the two major types of changes that are practical. Neutral sulphate allows recovery of the saltcake. Systems operating at lower acidity require addition of a catalyst. System designs were originally at near atmospheric pressure, with modern systems under significant vacuum (22" water column). Integrated systems make sodium chlorate from NaCl, with added system complexity.

Reducing agents now are typically H₂O₂ or methanol. Site specific concerns may favour one over the other.

Small generators are being used for water treatment.

Ken Kendall of Weyerhaeuser described the MoDo integrated ClO₂ system at Longview, WA. Chlorine, electricity and dionized water are the feed streams.

Ed Bechburger of Sterling talked about implications of pushing a chlorine dioxide generator for maximum capacity. Considerations include safety and hazard reviews for changes, including regulatory permits, operator attention, reliability, significant or marginal increases, trade-offs in efficiency and operability, and cost (is replacement an option?).

Each piece of equipment and supporting process should be reviewed for its contribution to the expected capacity increase, trying to assess the limitations. Mass flux is impacted by the fixed equipment (size of the vessels), and mass flow. Minimise water inputs with proper mechanical seals, high strength methanol (80% v/v) and 700 g/l chlorate solution. More frequent liquor tests (every 2-4 hours) are recommended when pushing the system. Filters should be cleaned once a week. De-ionised water is one way to improve a system that is plagued by other minerals entering the system. Operating parameters such as heat transfer will need to be optimised, where shell side fouling can be a frequent problem.

Absorption towers can be optimised with special packing, water distribution systems (designed for the new, higher rate). Some mills make 13-14 g/l chlorine dioxide solutions, however, the explosion hatches should be reviewed for this condition. Saltcake filters can be optimised to more efficiently remove the crystals. Systems are unique so what helps at one system may actually hinder another installation.

Dennis Owen added comments about system safety where explosions have damaged the equipment. These are severe situations are usually attributed to improper maintenance and contaminated feed chemicals.

Dan Blevins facilitated a brain storming session regarding "hot" research topics that should possibly be investigated. Several topics were presented, with discussion about what information is already available. It was noted that often the context of the previous research might limit its usefulness regarding unobstructed thinking about future opportunities.

Eric Fletty of TAPPI discussed the 2010 Vision committee and provided a handout to each of us about this effort. This is an effort by 21 volunteers to review the direction of TAPPI from an overview perspective, looking some 10 years in the future. The changes that have been made and accepted by TAPPI ‘s management include making participation easier, less TAPPI paid employees and the associated layers, bureaucracy, and time lag to disseminate information.

Dan Blevins added comments regarding the definition of the word "community" as used by this effort. Open discussion followed. Further discussion is encouraged and should be sent to Eric Fletty.

Summary of the 2010 Vision

At the request of the membership, TAPPI’s Board of Directors has looked at ways to modernise TAPPI so that it is streamlined, nimble, and responsive to members' needs now and in the future. We call this change the 2010 vision (nothing to do with the year 2010).

TAPPI members will have

• The opportunity to be involved in member communities that:

• Are easy to participate in
• Deliver high value to those involved
• Operate with minimal rules and maximum flexibility
• Are free from cumbersome structures and processes
• Are easy to form as new needs arise

• Products, services, information and staff competencies that are aligned to industry needs
• A more responsive association that can move more quickly to meet their needs

• TAPPI is a good organisation that wants to become great organisation
• We are changing to stay relevant and to continue to meet the needs of the members and the industries we serve

A group of 21 volunteer leaders and staff members served on the 2010 Committee. Several months of research, study, and analysis led to a proposal to TAPPI’s Board of Directors.

• TAPPI’s core purpose and values:

• TAPPI will continue to focus on what brings value to members:

• Access to technical information and experts, including peer interaction
• Content that is directly and immediately relevant
• Immediate accessibility, often on-line
• Industry information and news

Teams of volunteer leaders and staff are currently working on several areas of transition including Membership, Knowledge Management, Product Development, On-Line TAPPI, Bureaucracy Busters, Community Development, and Communications.

Watch for more information in TAPPI JOURNAL, on TAPPI’s website, and in the mail or call TAPPI’s International Service Line at 1-800-332-8686 (US), 1-800-446-9431 (Canada) or +1-770-446-1400.

TAPPI plans to market a web site (www.bleachplant.wego.com) for this committee, once an advisory group is organised. If anyone is interested, please contact:

Eric Fletty, Technical Operations Manager

TAPPI

Tel: +1-770-209-7535

fax: +1-770-446-6947

[email protected]

http://www.tappi.org

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Weyerhaeuser at Longview, WA hosted the mill tour.

Description of the mill

The fiberline is now 5 years old this month. It is a single line with a 1250 t/d 2 stage vapour phase Kamyr digester followed by a pressure diffuser. The pulp then goes through deknotters and pressure screens, and to a displacement wash press. This feeds a single-stage oxygen delignification system. Another wash press follows this before the brown HD storage. After the storage, a compaction baffle filter serves as an open wash stage before the three stage bleach plant. The sequence is D₁ (Ep) D₂. The unique thing is the three grades: Fir, hardwood, and hem-pine blend. These three are rotated in a 4 day cycle. A fourth grade, low brightness fir grade is without D₂ chemicals for 68 br.

Now they do not add oxygen to the Epo stage as originally designed. This is because channelling occurs, especially on hardwood. The diffusion washers on each stage could not handle any significant volume of gas, especially with the large diameter towers. Pulp channelling was a significant problem, causing very long transitions at each grade change.

List of meeting attendees on the Pulp Bleaching Committee:

Other attendees not on the committee: