1. Kamloops Modernization Project - Gary Berndt, Weyerhaeuser

1.1 Why did Kamloops choose this type of oxygen delignification system?

• literature review
• review of new systems installed
• discussion with Paprican

• need to be compatible with TCF (need maximum delignification)
• incorporate water reduction

• wanted a wash press as the last washing device
• "Poor Man’s system" can only get 25% delignification
• limited flexibility
• limited ability to reduce water
• wash press provides a temperature and pH break between brown and bleach, could also do some recycling of Do filtrate to press screw, Eop filtrate to No.2 press

1.2 Why did Kamloops choose the equipment suppliers?

• several suppliers were not able to supply the desired two stage system
• chose Ingersoll Rand (Beloit) for major equipment - 15 minute first reactor, 60 minute second reactor
• HA Simons for engineering
• Chemetics for white liquor oxidizer

• BOC supplied oxygen plant

• Ahlstrom supplied MC pump
• Komax steam mixer
• Beloit 1.2m x 4.5m wash presses – two twin roll, 4.5% feed, 35% discharge
• Kajaani supplied kappa analyser

1.3 Start-up

• started up system November, 1997
• used computer based training (CBT) system and simulator to prepare operators
• all valves had ID tags attached
• several problems on start-up
• process air vent plugged
• wash press design flaw – plugging
• stock line and blow tank vibration
• corrosion in oxidizer, so ran in thio mode
• alkali dose too low
• corrected over Christmas down
• 1167 ADMT/day @11%
• raised digester kappa target, did some OD optimization trials
• now getting kappa 32 to 19 through OD for a 40-45% delignification average
• ClO₂ reduction about 25% (compared to 23 Kappa at digester)
• Pulp properties – no change
• Yield increase – 1-2%
• Next steps – want 50% delignification with no effect on pulp properties, will trial recycling bleach filtrate

2. black liquor carryover to oxygen delignifcation – a summary of available literature - Joel Young (presented by Rae Cunnington)

The complete literature survey on this topic will be distributed to all attendees.

1. What is carryover, and how can it be measured?

• Recommend SCAN-CM 45:91 – water soluble organic matter test (COD)
• Most important – use a consistent test

2.2 What carryover has most impact?

• Raw black liquor solids have significant impact on O stage, while oxidized solids have little impact on O or ClO₂
• Impact level is in the range 75-150 kg RBLS/ODt at Hinton, others feel it is less
• Focus should be on pre-oxygen washing rather than post-oxygen washing

2. delignification capabilities and operating conditions for mini, mc, and hc oxygen delignification systems Norm Liebergott (presented by Ross Anderson)

• Kappa number reduction in Oxygen Delignification Systems
• Mini – 20-30%
• Medium Consistency – 40-45%
• High Consistency – 45-50%
• Double oxygen stages – 50%-70%

• Delignification challenge – maximize delignification while minimizing carbohydrate reactions
• Reaction constraints
• Mass transfer – needs high oxygen pressure and large interfacial area
• Kinetics – slow phase accelerated by alkali concentration, temperature, and oxygen pressure
• Thermodynamics
• Stoichiometry – 0.1-.013% NaOH or oxygen (OD basis) per unit Kappa reduction, products are CO2, organic acids, CO, CH₃OH

• Effect of incoming Kappa Number - lower kappa, lower viscosity and yield
• Major process variables in Oxygen Delignification

1. Consistency
2. Temperature
3. Time
4. Alkali Charge (pH)
5. Magnesium
6. Black liquor carryover – up to 10 kg Na₂SO₄ does not seriously affect delignification
7. Filtrate recycle
8. Source of caustic
9. System pressure
10. Oxygen charge

• Main Reactor Designs
• High consistency – remove most of liquid phase, so less heat, less dissolved solids
• Medium consistency – oxygen finely dispersed, so mixing is critical
• Multiple Stage – no wash between reactors
• Poor Man’s – retrofitting an existing system
• Om Process – leaching stage (Union Camp)
• OxO Process – lignin activation between stages
• Ultima O Process – no wash between D and second O
• Advantages Summary
• Decreases lignin into bleach plant
• Minimal effect on environment
• Low chemical cost
• Allows "low AOX" bleaching
• Drawbacks Summary
• Selectivity limitations
• Increased load to recovery
• Excursions from optimum conditions affect strength

• Process Improvements
• Pretreatments
• Cellulose protectors
• Transport of oxygen to lignin
• Multi-stage oxygen
• Lignin activation
• More efficient equipment

2. troubleshooting chlorine dioxide generators - Dennis Owen

Copies distributed to attendees. The basis for this troubleshooting guide is the Kepner Tregoe method of troubleshooting analysis.

1. Problem prevention – do the routine PM and inspections
2. Determine the problem – full and accurate description from operators (keep mouth closed and ears open)
3. Describe and specify the problem – KT uses 4 forms

• What – is, is not, distinctives, changed
• When – is, is not, distinctives, changed
• Where - is, is not, distinctives, changed
• Extent - is, is not, distinctives, changed

1. Find the true cause
2. Verify the true cause
3. Choose the corrective action

5. High yield pulping and bleaching strategy for aspen kraft pulp - Dave Senior

This paper will be presented in Helsinki next week, so could not be appended to minutes. Copies are available from Dave after the Helsinki presentation.

• Objectives – identify optimal conditions in the lab for pulping, oxygen delignification and bleaching of aspen to balance yield loss and reduction of chlorine based chemicals.
• Method – determined yields for various aspen pulps produced with and without AQ, enzymes, and oxygen delignification
• For hardwoods there is a significant drop in yield below about 15 kappa number
• AQ resulted in a 0.7% increase in yield, mostly hemicellulose but also slightly higher rejects
• Oxygen decreased yield of aspen
• AQ protected yield loss in oxygen pulps
• High kappa pulping and use of oxygen, AQ, and enzymes all increase pulp yield, bleachability and increases production efficiency

6. progress report on low consistency ozone bleaching - Gord Homer

See Gord for a copy of this paper

• Can save up to 12 kg ClO₂/ADt with D/Z EopDED and 0.6% ozone (see flowsheet in Appendix)
• Optimum conditions for D/Z at 4.5 Eop kappa number:
• 0.3% ozone on pulp
• savings of $5.50/Adt pulp (based on ClO₂ at $1.50/kg)

• strength is good
• low consistency retrofit very promising
• medium consistency off-the-shelf technology is readily available