ABSTRACTS PACWEST 2008
(Subject to possible additions and/or changes)
Session 2A –
KRAFT
1 Tubular
Backpulse Pressure Filters: Identification of
Acid-Insoluble Filter Plugging Compounds And
Optimization Of Acid Washing Procedures
Rich
Adderly, Gavin Baxter,
Tembec Industries Inc, Skookumchuck
Operations; Kevin Taylor, Taylor
Industrial Research, Inc.
Tubular backpulse pressure
filters are commonly used in Kraft mills for clarification of white liquor and
weak wash. Filter replacement due to
plugging can cost approximately $40,000 per filter unit and may result in mill
downtime. Acid washing of filters is
commonly used but is not always effective.
In this study, acid-insoluble filter-plugging materials are identified
by SEM/EDS and XRD in both polypropylene and Gore-Tex™ membrane filter
socks. Calcium sulphate (gypsum),
calcium phosphate (hydroxylapatite), metal sulphides
and carbon were identified as major filter-plugging components. Detailed sampling of both the standard acid
washing procedure and a modified procedure were carried out, with detailed
sample analysis.
Calcium sulphate (gypsum) formation on the filter was
shown to result from significant hydrolysis of sulphamic
acid solutions used to clean the filters.
Modification of the acid washing procedure greatly reduced the amount of
gypsum present as a filter-plugging component.
Addition of a surfactant to the acid reduced wash time and was able to
mobilize some of the carbon from the filter.
With surfactant, acid wash was 95% complete after 40 minutes. In this work, modified acid-washing
procedures improved filter washing.
Potential methods to remove acid-insoluble filter-plugging materials are
discussed.
2 Effects
of Extractives from Mountain Pine Beetle Attacked Lodgepole
Pine on Kraft Mills
Larry
Allen, Alain Gagné and Paul Watson1, FPInnovations - Paprican,
1 Now with Canfor
Pulp LP,
This report addresses the impact of
mountain pine beetle infestation on several extractives-related issues in kraft pulp mill operation: extractives in pulp, pitch
control, and effluent treatment. Work in separate reports has shown that the
use of infested wood usually causes higher extractives (especially increased
resin acid content) in the wood to the digester and this results in an increased
solubility of fatty and resin acid soaps in black liquor. Hence the use of
infested wood resulted in a greater extractives load to be removed in brownstock washing for good pitch control. Use of green and
red stage wood did not cause a significant change in the normal amounts of
extractives in pulp across the bleach plant and at the pulp machine. In the
mill using gray stage wood, the solubility of
extractives in black liquor was even higher and brownstock
washing was more important for their removal. The amount of extractives,
especially the unsaponifiables, in the final pulp was
significantly higher in the mill using gray stage
wood. In this mill, the resin acid concentration in the final effluent was
high. The gray stage results require further confirmation
in more mills.
3 MgSO4 vs Mg(OH)2 as a Cellulose
Protector in Oxygen Delignification
Jean Bouchard, Jie Wang and Richard Berry,
FPInnovations - Paprican,
If the selectivity of oxygen delignification
is not properly controlled, loss of pulp viscosity and ultimately pulp strength
can result. It is well known that adding a small amount of magnesium sulphate
significantly reduces cellulose damage and improves selectivity. A chemical
supplier has proposed that magnesium hydroxide can replace magnesium sulphate
as a cellulose protector. The claimed benefit is an identical cellulose
protection but at lower cost. We evaluated this claim using four unbleached
softwood kraft pulps provided by Member Companies. We
found that, with all the pulps, selectivity improved when using soluble
magnesium sulphate but that little or no selectivity improvement was obtained
when using insoluble magnesium hydroxide; magnesium ions in solution appear to
be needed. It was further observed that in-situ iron concentration in
unbleached pulp affects oxygen delignification
selectivity while in-situ calcium concentration affects magnesium protection
efficiency. Our results favour the hypothesis of Mg-carbohydrate complex formation
as the major mechanism of cellulose protection by magnesium in oxygen delignification and lead to the recommendation to use a
soluble magnesium compound to improve selectivity in an oxygen delignification stage.
4 The
Effect of Pulping Mountain Pine Beetle Killed Wood on Tall Oil Soap Recovery
Vic
Uloth, Ron van Heek, FPInnovations
- Paprican, Prince George; Paul
Watson1, FPInnovations -
Paprican, Pointe-Claire, QC.
1 Now with Canfor
Pulp LP,
Soap solubility
tests and soap analyses, using black liquor and
soap samples from four B.C. mills, and one Alberta
mill pulping very little beetle killed wood, indicate
that tall oil production at mills pulping beetle killed wood
could drop substantially due to higher soap solubility in black liquor, a
reduced tendency for the soap to "float" off in storage vessels
and skimmers, and lower soap quality (acid number). The change in soap
solubility, and a reduced tendency to float to the
surface of the black liquors, is largely a result of changes
in the fatty acid (FA) and resin acid (RA) content
of the wood, resulting from beetle attack and subsequent
fungi infestation. The FA/RA ratio in tall oil produced from soap
skimmed in the mills pulping beetle killed wood
has dropped from 1.49-1.86 in the mid 1980s
to 0.72-1.28. This has shifted the soap solubility versus black liquor solids curves up and to the
right. The solids concentrations at which
soap solubility is minimized are now consistently
in the 35-49% solids range. In the 17-32% solids range, where most B. C. mills
try to skim soap, soap solubility increased significantly. Soap concentrations in weak BL samples from
these mills (11.6 to 32.6 kg per tonne of dry black liquor solids (kg/TDBLS))
did not greatly exceed the solubility limit (10.5-23
kg/TBLS) in the 17-32% solids concentration range.
While little soap would be recovered in these mills, soap could be expected
to precipitate at higher solids
concentrations, aggravating evaporator and concentrator
scaling problems and accumulating in strong liquor storage tanks, where
it could cause further operating problems.
Increasing soap concentrations in fired black liquor were found to increase the viscosity and heating value of the black
liquor. While increasing the firing temperature
by a few degrees was found to reduce the viscosity to baseline levels,
the soap decreased the swelling propensity of the liquors, making
them much more difficult to burn. Tests in two recovery
boilers indicate that without
operating modifications (ie.
keeping the gun pressures, liquor firing temperature
and combustion air splits constant), high concentrations of
soap in the fired liquor lower the char bed temperature and increase
burning in flight and carryover levels in the upper boiler.
5 Chip Screening Fire at Canfor's Prince George Pulp Mill (Presentation only)
Rod Duncan, Canfor Pulp LP, Prince George
On January 15th
2008 fire destroyed Canfor’s Prince George Pulp and
Paper Mill’s Chip screening building and digester chip infeed
conveyor. 30 hours later the Paper
Machine was running on repulp, 5 weeks after the fire
a temporary chip feed system was complete and the Pulp mill was restarted.
The presentation
will review the damage caused by the fire, the options investigated to restart
the Pulp mill, the demolition of the damaged structures and equipment, the
installation of the temporary feed system, the performance of the temporary
system and the plans for the permanent system.
6 Training Program Development at the
CPLP Pulp Mills
Jeff Bennett, Canfor
Pulp LP, Prince George
The aging workforce at the
CPLP pulp mills in
The training
program development started with a Needs Assessment to determine what the Team
Leaders thought was important for their operators to know. After reviewing the programs at a number of
other pulp mills and looking outside the industry as well, a program was
developed which combined elements of a checklist, student handbook, and
traditional manual. Additional reference
material has been developed to provide process operation information. The training program also includes timelines
for learning each position and an evaluation process to check the competency
before signing the person into the new position.
Session 2B – PAPER MACHINE TECHNOLOGIES
1 World’s
Largest Newsprint Line:
Martti Tuomisto,
Metso Paper USA, Inc.
On
The fiber furnish is 100% recycled. For supplying PM 4
with DIP pulp, Chenming Shouguang
installed a 1500-tons-per-day deinking line, which is
also the largest one in the world.
This technical paper outlines Chenming’s
PM 4 project scope section by section, including the new paper machine, winders
and related production systems and equipment. Also, startup and production
experiences as well as newsprint quality aspects are presented.
2 Evaluation
of Gap Forming Rebuild Options: Part I -
Quality Improvements with Maximum Reuse of Existing Drainage Components
Jay. A. Shands, Vaughn J. Wildfong,
J. Ronning, M. Condon, M. Bouchard, J. P. Lajoie, Johnson Foils, Springfield, MA
A gap former rebuild is presented that offers
significant paper quality improvements while maximizing reuse of existing
drainage components. Rebuilds of four
paper machines with formers of varying design, running different furnishes
producing newsprint is reported on.
Rebuild performance was evaluated relative to sheet structure including Ambertec formation, total fines and mineral fines
sidedness, porosity, and smoothness sidedness.
The effect of the rebuild on capacity and CMD basis weight profile is
also discussed.
The effect of counterblade
loading strategy and vacuum management on sheet properties is evident. Significant improvements in post rebuild
target properties were exhibited on all four machines. The number of counterblades, counterblade
loading, and
application consistency all effect final sheet properties. Additionally, inclusion of a pre-couch
suction box simultaneously allows for increased capacity and management of early forming zone
vacuum distribution to optimize formation and sidedness.
3 Steam & Condensate
Systems: Considerations for Dryer Section Runnability
Pekka Kormano, Deublin
Steam Systems LLC, Buford GA
This paper provides insight on the effect of the
S&C system on dryer section runnability,
including examples of typical problems that might be encountered. General
guidelines are reviewed for modern S&C system design consistent with good runnability, such as individual control of dryers,
determining steam group sizes and group splits, curl control groups, acceptable
compromises, etc. Examples are given for the type of S&C upgrades
recommended during dryer section modifications such as converting to unorun or single tier, installing a shoe press, changing
from a puddle type size press to a metering blade type, S&C requirements
after non-contact drying, etc.
4 Steam Box Design has Changed!
Patrick
Neill, Bob Vyse, T. Steele, Honeywell, Vancouver
Steam box operational basics have not changed, but the
design continues to evolve. Mills are
increasingly concerned about energy usage and at the same time improved CD
moisture profile control.
Steam boxes today are emphasizing CD moisture control
more than production increases and as a result simpler boxes with narrower
zones are the norm. Lower steam usages
often result.
Operationally the continued demand for reduced
maintenance has led to the development of new actuators along with on line
diagnostic systems. Steam boxes are
designed for better cleaning possibilities.
The introduction of scanning CD moisture profile
measurements prior to the dryer section has allowed the decoupling of press and
dryer section problems as well as the possibility to better understand the
origin of CD tension profiles at the reel.
Multivariable CD control systems have added a new
dimension to overall paper machine profile improvement with emphasis on energy reduction
scenarios.
This paper will review the noted developments and add
insight into the use of steam boxes for paper machine optimization
5 IR Dryers as a Tool in the Press
Section
Dr. Peter Fisera, Andritz AG; Tim Klemz,
Compact Engineering
The perceived low energy efficiency of infrared has
prevented its widespread adoption as a means to increasing moisture removal
when applied to the sheet before the last press. The conversion efficiency of
primary energy into infrared and subsequent absorption of this energy by the
sheet is in the region of 60% when the energy is emitted at wavelengths longer
than 1.35μm. Taken in isolation, this level of efficiency is too low when
compared with the cost of steam in hot air dryers or cylinders. There has also
been concern that the high intensity of infrared would have a detrimental
effect on the quality of the fibre.
The quality and efficiency aspects of using high
intensity short wave infrared to increase the moisture removal from the sheet
have been the subjects of exhaustive trials by Andritz
on their pilot plant in
The combination of pre-heating the sheet and increased
dewatering at the last press increases the efficiency of primary energy use
enormously. The sheet dryness increases significantly following infrared
heating and press dewatering. This double effect, increasing both the sheet
solids and sheet temperature prior to the main drying mode, contributes to an
overall higher increase in drying capacity than the direct use of primary
energy at 60% efficiency would suggest.
Heating the sheet prior to the last press requires a
different approach to the application of infrared than if a surface effect were
required, such as the drying of an aqueous coating on a thin sheet of paper. To
be effective, the infrared needs to be able to penetrate the full bulk of the
sheet, while at the same time minimising losses from the system due to
reflection and transmission.
Gaining penetration to the middle of the sheet and
maximising absorption of the infrared by the cellulose requires the generation
of the correct wavelengths of infrared. If the wavelength is less than
1.2μm, the energy will pass straight through the sheet and if it is longer
than 2.1μm, 80% of the output will be absorbed by the first 20μm of
sheet thickness. Emitting the infrared at a peak output wavelength of
1.35μm ensures that the entire sheet mass is heated almost isothermally so
overheating of the sheet surface will not occur. Furthermore, the free water
present on the surface of the wet pulp where the infrared is applied evaporates
and cools the sheet surface once the required sensible heat has been applied.
Short wave infrared dryers need to be cooled to
optimise their performance and maximise the working life of the high
temperature components. The cooling air absorbs up to 30% of the input energy
and when it is exhausted from the dryers it has a very low %RH and a
temperature in excess of 130oC. Feeding this exhaust air in to the
makeup air of the hot air dryers following the press section significantly
increases the overall thermal efficiency of the infrared application.
Both of the concerns mentioned at the beginning have
been tested and evaluated and some important findings and results will be part
of the paper along with an overview of the equipment used.
6 MODERN CALENDERING –
PROCESS STABILITY, SHEET STRUCTURE, UNIFORMITY AND SYSTEM CLEANLINESS
REQUIREMENTS.
Przem Pruszynski ,Nalco Company,
Recent
advances in calendering technology and demands on
quality and production cost of supercalendered grades
created new requirements for process stability, formation, sheet
structure and system cleanliness. Supplying consistent and optimally structured
sheet to the calender may allow papermaker to improve
results especially with the most aggressive calendaring processes. Nalco has been focusing on grade-specific
approach in every major application for last few years. Some of our experiences
for calendered grades were described in this paper. This
paper reviews most important sheet properties, operational best practices,
structure-properties relationships relevant for results of calendering
operation. Literature review, practical mill data as well as future development
suggestions are discussed in this paper.
7 New
Steambox - Same Objectives but Significantly Better
Results
Chris Rapp, Metso Automation,
Steambox technology has come a long way and now
actually delivers what it is actually supposed to. The new design features a
new unique design and electromechanical actuators with actual position
feedback. This paper talks about this new design and how it transfers high heat
into the sheet at relatively lower steam consumption. Steambox
benchmarking studies done over the past couple years supports the fact that new
steambox is much better in overall heat transfer
efficiency as compared to conventional design. The return on investment is
anywhere between 3 to 9 months just in lower operating costs as compared to
conventional steamboxes. With the energy prices the
way they are, new steambox deserves a serious
consideration, when it has the potential of savings in total cost of
production.
Session 3A – PULP
PROPERTIES
1 Towards Overcoming the Brightness Ceiling of Mechanical
Pulps Prepared from Blue-Stained Lodgepole Pine Chips
Thomas Hu, Trevor
Williams, Shabnam Yazdi,
Lars Wallbacks, FPInnovations -
Paprican Division, Vancouver; Paul Watson, Canfor Pulp
LP,
The initial brightness of TMP and CTMP prepared from
chip blends containing mountain pine beetle-infested (kill date = 2-3 years),
blue-stained lodgepole pine is up to 5.0 ISO points
lower than that of the pulps made from the green chips. Paprican’s
VIS-NIR system is capable of accurately predicting the blue-stained chip
content in the chip blends on a pilot-plant conveyor.
TMP made from chip blends with various blue-stained chip contents all have
lower sodium hydrosulfite (Y) bleach response than pulp made from the green
chips. A method to overcome the brightness ceiling of Y-bleached TMP made from a
chip blend with 25% blue-stained chip content has been developed. The method
involves the addition of 0.2% (o.d. pulp) of sodium borohydride to Y bleaching of the pulp.
A high bleaching end pH (~10.0) in alkaline hydrogen peroxide bleaching removes
most to all of the blue stain in TMP made from the blue-stained chips. Under
optimal peroxide bleaching conditions, TMP made from 50% blue-stained chips or
CTMP made from 100% blue-stained chips was bleached to the same brightness as
TMP or CTMP from green chips. TMP from 100% blue-stained chips was bleached to
within 0.8 brightness points of TMP from green chips.
2 Improving
the Properties of Thermomechanical Pulp from Beetle Killed
Lodgepole Pine
Ingunn Omholt, Keith B. Miles, Michael Stacey, Michael Hellstern, FPInnovations - Paprican,
Pointe-Claire
The
future wood supply for papermaking in
The
results from pilot refining trials showed that low-intensity refining in the
post-primary stages of the early-grey and the late-grey TMP improved the fibre length, but it did not affect the tensile index at a
given CSF significantly. Chip presteaming and water
impregnation had a marginal effect on the pulp properties of the late-grey TMP
when compared at a given CSF. In this
case the wood had a moisture content of about 17%, and there was only a small
difference in strength properties between this wood and green wood. It is possible that the effect of rewetting
might have been greater if the wood had been drier. Sodium bisulfite
pretreatment at pH = 6 coupled with low-intensity refining of the late-grey
chips gave, however, a positive effect on the tensile index at a given
CSF. Process modifications involving
careful bisulphite pretreatment could be investigated
further if loss of tensile strength due to beetle killed wood becomes a greater
problem in the future. It could also be used as a way to improve the unbleached
pulp brightness. Reducing the refining intensity could represent a possible
solution if maintaining the fibre length becomes a
critical issue. Both these modifications
led to somewhat increased refining energy consumption and there were also some
negative effects on other properties that need to be taken into consideration.
3 Surface
Characterization and Surface Modification of Mechanical Pulp Fibres
Kecheng
Li, Department of
Chemical Engineering,
Mechanical pulps including CTMP, APMP and TMP have
distinctively different fibre surface with regards to the chemical composition
and physical structures. When fibre
separation in refining occurs in the middle lamella region, the lignin-rich
middle lamella material will remain on the fibre surface. In TMP refining, lignin melts at high
temperature and melted lignin may form a coating layer on the fibre surface.
Lignin on the fibre surface forms a barrier to
inter-fibre bonding, hence affecting negatively the inter-fibre bonding
strength and, in turn, the paper physical strength. In this paper, we have used XPS/ESCA, AFM to
identify the chemical composition and the nano
structure of the fibre surface of various mechanical pulp. We have also developed a mechanical peeling
method and a bio-surface modification method in order to remove the surface
lignin or activate the fibre surface for improved inter-fibre bonding.
4 The Efficiency of Softwood Kraft Pulps in Improving Paper
Machine Runnability
Ivan Pikulik, Xujun Hua, Norayr Gurnagul, FPInnovations - Paprican, Pointe-Claire
Softwood kraft pulp is
commonly used in papermaking to improve paper strength and machine runnability. The performance of a softwood pulp depends on
the fibre morphological structure which in turn is
related to species and their geographic origins. We have evaluated the
reinforcing properties of three softwood kraft pulps
which were used in a fine paper mill to improve paper machine runnability. Our method was based on the measurement of
wet-web tensile strength, stretch, tensile energy absorption, and failure
envelopes of handsheets, combined with the evaluation
of water removal characteristics of pulps. Our results indicate considerable
differences in the reinforcement potential of the three pulps. At an equal
refining energy, the Canadian softwood kraft pulp was
found to have the highest dry sheet strength and to provide the best
reinforcing properties for wet webs. The Scandinavian softwood pulp was next in
terms of reinforcement potential, followed by the South American sample which
had the lowest wet-web strength at an equal solids
content among the three softwood pulps. Canadian softwood kraft
pulp required the least energy for refining to the same freeness of 545 mL in a laboratory PFI mill, followed by the Scandinavian
pulp and the South American pulp. The Canadian and South American softwood
pulps improved wet-web tensile strength at all blend ratios investigated in
this work, and wet sheets made from a blend of these pulps with hardwood had
greater tensile strength than those made from 100% softwood. The Scandinavian
pulp did not improve the wet-web strength. The pulps used in this work are not
necessarily representative of their regions of origin, but the method described
can be used for comparing the reinforcing properties of various pulps.
5 Effects of
Extractives from Mountain Pine Beetle Attacked Lodgepole Pine on TMP Plants
& Paper Mills
Larry
Allen, Alain Gagné and Paul Watson1, FPInnovations - Paprican, Pointe-Claire
1 Now with Canfor
Pulp LP,
This report assesses the impact of using mountain pine beetle infested
wood in integrated TMP and paper mills on extractives-related issues, such as:
extractives in pulp, pitch control, friction properties of paper, and effluent
treatment. Use of infested wood in TMP pulp and paper mills did not seem to
cause significant changes in the normal amounts of extractives and their
chemical composition across the mills. Use of a pitch dispersant for pulping of
green and red stage infested wood to prevent plugging of grooves in refiner
plates may be necessary due to the high variability in extractives levels. The
friction properties of newsprint from infested wood were within the normal
range for newsprint. Effluent treatment plants successfully reduced the
extractives of effluents during use of infested wood to near-zero values. As
only three mills were involved and none was using gray-stage wood, the results
are preliminary.
Session 3B -
NOVEL TECHNOLOGIES
1 Wet End Control Applications using a Multivariable
Model Predictive Control Strategy
Stephen Chu, Honeywell,
This paper discusses the use of a SpectraFoil
MD sensor on a fine paper machine to monitor the pre Dandy Roll consistency and
the use of this data in an overall control scheme designed to increase sheet
filler content (measured at the pre size press scanner) while maintaining online sheet formation within a desired
range. The control scheme is based on a
multivariable model predictive control strategy. The paper will discuss the key manipulative
variables and controlled variables used and the results obtained.
2 Wood Pulp Based Filters for Removal of Nano-Scale Particles Suspended in Air
J.
Mao, J. Kadla, R. J. Kerekes,
Pulp and Paper Centre, University of British Columbia, Vancouver; B.Grgic,
W.H. Finlay, Aerosol Research Laboratory, Department
of Mechanical Engineering, University of Alberta, Edmonton
This paper describes research on a potential new use
of wood pulp fibre as a medium for filtering virus-size particles from air. The
aim is to meet the demanding objective of an N95 filter recommended for
health-care workers: high particle capture efficiency (≥95%) of all
particles, at a low pressure loss (≤ 250 Pa for comfortable
breathing). Such filtering is typically
accomplished by filters made of charged synthetic fibers.
We have produced filter pads from northern softwood kraft pulp by a process of wet beating, wet forming, and
partial freeze drying to retain surface fibrillation. Tests on aerosol particle
capture have shown that the “filter quality index” of our filters (combination
of capture efficiency and pressure loss) is in the low range of N95 filters.
Unlike N95 filters made of synthetic fiber, our
filters rely solely on mechanical filtration. They have the added advantage of
being produced from renewable resource and allowing disposal by incineration as
a carbon-neutral fuel.
This study is a project in SENTINEL, the Bioactive
Paper Network of Canadian universities.
3 Web
and Roll Performance Characterization: a
Better way to Ensure Good Runability in Pressroom
Frédéric
Parent, Jean Hamel, FP Innovations – Paprican, Pointe Claire
Some of customers' complaints related to wrinkles, misregistration or paper break can be related to
non-uniform paper properties such as bagginess, winding non-uniformity or web
defects. For mills, it is often very hard to detect these problems during rolls
production. Over the last few years, Paprican’s
research activities have led to the advancement of knowledge on paper runnability, defects in winding, paper breaks and web
bagginess. The application of these findings has led to the development of the
Roll Testing Facility (RTF) which can simultaneously evaluate web and roll
structure. The RTF provides a unique tool to evaluate roll structure, web
characteristics and web behaviour, and to evaluate how a web issue may be
related to winding and paper machine operation. This paper will demonstrate how
the Roll Testing Facility can be used to measure and diagnose issues such as
bagginess, web wandering, winding uniformity and splicing issues.
4 ‘SmartChips’ for Kraft Pulp Digesters - Presentation only
The pulp digester is the first reactor used in the
conversion of wood chips to pulp fibre. Optimized
digester performance is important for obtaining maximum production of the
highest quality pulp possible and for enhancing operation of the entire fibre line. The goal is to uniformly treat/react each wood
chip that enters the digester. However, the uniformity of treatment is unknown.
The limited data available for batch digesters and results of computer
simulations made for continuous digester operations indicate that significant
differences do exist. Industrial experience confirms this with increasing digester
size attributed to reduced liquor flow uniformity that leads to operational problems,
accelerated corrosion, fluctuations in extent of delignification
and poorer washing efficiency. Further, most available data are limited to
fixed locations at the boundaries of the reactor.
Today’s presentation describes ongoing work at UBC to
develop an autonomous flow-following micro-sensor (‘SmartChip’)
that can be released into industrial chip digesters, measure and record desired
process variables as a function of time, withstand reactor conditions, and be
retrieved intact for data analysis. To do this, the SmartChips
must be small, robust, neutrally buoyant, and locatable. SmartChips
will move through the digester like wood chips, but instead of being pulped,
will measure hydrostatic pressure (axial position), temperature (allows the
H-factor to be calculated) and chemical concentration (chemical profiling in
the digester) during its passage. Sequential passes of a SmartChip
or deployment of multiple SmartChips will allow
variability to be quantified permitting operating strategies to be improved.
The talk will focus on the design issues for the SmartChip
and our progress-to-date towards sensor and platform development. The potential
benefits for the pulp and paper industry are significant. In addition to
providing understanding of what is actually occurring to chips during the
cooking process there are economic benefits. As an example, worldwide kraft pulp production is valued at approximately $50
billion/year. Improved digester operation through better control and reduction
of process variability would allow production and uniformity to be increased. A
1% improvement in pulp throughput (a modest gain) would net $0.5 billion a year
world-wide. In
Session 4A – ENVIRONMENT
1 Impact
of a Kraft Mill Closure on Ambient Levels of Particulate Matter (PM2.5)
in the Community
Brian O’Connor, FPInnovations
- Paprican,
Ambient
PM2.5 monitoring and chemical characterization
were conducted in a kraft mill town during
operation and after the permanent shutdown of the mill. Analysis of the data
collected during this period indicated that the mill emissions were not
contributing significantly to the elevated levels of PM2.5 in the
community on an hourly or a daily basis. For the 1-h data points, the range of
PM2.5 concentrations for winds coming from the direction of the mill
was similar before and after the mill shutdown. While the mill was found to
have an influence on the distribution of 1-h PM2.5 concentrations in
the 10–20 µg/m3 range, the higher values (i.e., > 20 µg/m3),
which would contribute to poorer air quality, appear to be related to the long
range transport of ambient PM2.5, as opposed to PM2.5
produced locally. This suggests that other sources aligned with the direction
of the mill/monitoring station, such as an aluminum smelter and airport located
14 km downstream or long-range transport of PM2.5, were significant
contributors to the loading of ambient PM2.5 in the community.
With
respect to the chemical composition of the ambient PM2.5, the
closure of the mill did result in some apparent changes. For the two largest PM2.5
components, comprised of sulphate and the
unidentified organic fraction, the mill shutdown did not change the relative
amounts indicating that there are other significant contributing sources in the
area. The components that were found to be lower, after the mill shutdown, were
sodium, chloride, calcium, nitrate and the sum of the organic ions. While the
emissions from the direction of the mill were found to contribute to increased
levels of these compounds, it is important to keep in mind that all of these
components are ubiquitous to the area and were also present in the ambient PM2.5
samples collected from the direction of the town.
2 Recent developments and features of
ICT-1 Polysulphide Pulping and ICT-2 Foul Stream Decontamination
Irina Yeremey, Alexander Gorokhov, Industrial Catalytic Technologies Inc, Calgary; Don Towson, D. E. Towson &
Associates Inc., Calgary
Recent market trends, including rapidly increasing
costs of energy, chemicals, materials and fiber
supply, require kraft mill managers to be
particularly attentive to available process improvements and high-tech
products.
This work compares existing polysulphide
pulping technologies, describes reasons for poor acceptance by industry and
describes
Summarized results of experimental studies relating to
the two processes are also presented. The outstanding technical, economic and
environmental benefits of ICT-1 catalytic polysulphide
kraft pulp production by alone or combined with ICT-2
decontamination of mill foul condensates are highlighted. ICT products provide
Canadian kraft pulp industry with a unique
opportunity to greatly increase the competitiveness.
3 Pulp
and Paper Sludge as a Barrier Layer in Landfill Closure: A New
Mike Van Ham, SYLVIS Environmental,
Pulp
and paper sludge has historically been regarded as a waste material destined
for disposal. Disposal options traditionally include combustion or landfill
disposal. Allocating space and resources
to their disposal has become an increasing burden for many in the
industry. Beneficial use options have
been developed, most involving the application of these residuals to land for
soil amendment and fertilization.
Research has identified new opportunities for the use of pulp and paper
sludge as a low permeability barrier layer to isolate the contents of the
landfill from infiltration and resulting exfiltrate
production. Compacted sludge has been
used successfully as a barrier layer in landfill closure elsewhere in
Abitibi Consolidated’s Mackenzie Paper Division (Abitibi),
with the guidance of SYLVIS and the authorization of the Ministry of
Environment, elected to close a 1.4 hectare on-site ash landfill using a
compacted sludge barrier system. As part
of a performance evaluation a barrier layer comparison project was
completed. The objectives of the study
were to compare compacted clay, compacted pulp and paper sludge and a geosynthetic membrane for their effectiveness as a barrier
layer. A large above ground cell was constructed of each of the three
systems. The study was initiated in the
fall of 2004 and completed in the fall of 2006.
Lysimeters were installed above and below the
barrier layer to collect water for analysis and gypsum blocks were installed
below the barrier layer to quantify soil moisture. Two common soil water tracers were applied,
lithium bromide in summer 2005 and pentafluorobenzoic
acid in summer 2006. Results indicate
that all three barrier systems restricted water inputs to the subsurface
layers. The compacted sludge barrier layer appears to be performing in a manner
equal to that of the other barrier systems. The ash landfill was closed in
October 2006 with the use of compacted sludge as a barrier layer. The cost of the landfill closure was below
the average cost for similar closures throughout the province.
This
presentation will provide an overview of the comparison study and the
operational implementation of this barrier closure system in the closure of an
ash land landfill. The use of compacted sludge in landfill closure presents a
new opportunity for mills to use pulp and paper residuals in a low cost,
beneficial use option.
Gwen Vernham,
Ralph Lunn, and D. Sutherland, Zellstoff Celgar Ltd. Partnership, Castlegar
Process studies and lab
test results showed the foul condensate stripper at Zellstoff
Celgar was not meeting its design efficiency. Foul
condensates from the digester and black liquor evaporators are stripped with
500 kPa(g)
steam in a partially-integrated steam stripper. Chemical oxygen demand (COD in
mg/L) was used as a measure of methanol, TRS, and other COD-causing compounds
in the stripper feed and product. The stripped condensate product had high COD
content and the stripper overhead gas (SOG) was low in volumetric flow. At Celgar, the stripped condensate is part of the makeup to
the D1 filtrate in the Bleach plant. The poor quality of stripped condensate
was suspected of contributing to high bleach plant chemical costs and low
brightness of bleached pulp. Maintenance and hydro-cleaning work performed
during the 2008 Spring Shutdown has returned the stripper to original condition.
Now that the stripper is clean, the lime kiln (primary incinerator) and SOG
collection system has experienced operating problems related to the high
volumetric flow of SOG. Further work is required on the collection and
incineration systems to return the entire system to design performance.
Session 4B -
ENERGY
1 Adding
a Steam Turbine Generator to an Existing Old Pulp Mill
Derek McCann, AMEC, Vancouver
In order to make existing old small pulp mills more
profitable, an important objective is to reduce their energy costs. One possible method is to reduce/eliminate
imported electrical power or, more importantly, to export power and obtain
additional revenue. This method could
include adding a steam turbine generator to the existing steam plant.
Modern large pulp mills typically export power. Usually, they have two steam turbine
generators. One is an extraction/back
pressure type and the other extraction/condensing. Modern pulp mills are designed to minimize
process steam and electrical consumptions.
They also have high inlet steam conditions for the steam turbines, to
maximize power generation.
Existing pulp mills do not have these advantages. Consequently, adding a steam turbine
generator to an existing pulp mill is a technical challenge. This paper discusses various alternatives
that can be considered to meet this challenge.
2 Achieving
High Efficiency Thermocompressor Operation
Mike Soucy, Kadant Canada Corp.; Jim Maggard, Kadant Johnson Systems; Jerry
Timm, Kadant Johnson
Inc. Presented by Kevin Green, Kadant Canada
Thermocompressor sizing and operation are often misunderstood. Thermocompressors
that do not match the syphon design is a common
industry problem. Oversized thermocompressors
operating at differential pressures higher than required are common. It is not
unusual for thermocompressors to consume twice as
much motive steam as is required. This is common on machines that have
converted to stationary syphons without optimizing
the thermocompressor size. This paper explores the
latest development with high efficiency thermocompressor
design and its integration with syphons and dryer
drainage components.
3 Electrical
Energy Savings using Advanced Controls on a TMP Refiner System
Manny Sidhu, Carl Sheehan, Norpac Controls Ltd., Burnaby, BC; Stewart McLeod, Catalyst Paper – Port Alberni Division
The concept of energy conservation is becoming
increasingly important in order for
4 Energy Management and Conservation at
Surendra
Singh, Alberta
Newsprint Company
The pulp and paper
manufacturing process is very energy intensive. Among all the pulping
processes, the mechanical pulping requires the most electrical energy for
refining. The electrical energy has been a major cost input at Alberta
Newsprint (ANC) since power prices have been more than double in last number of
years. At ANC we have initiated/implemented number of projects to manage
electrical energy cost and usage. Recently “ANC Energy Management Team” has
been transformed in to “Energy Conservation Team” with focus on reducing energy
usage. Our goals for next two years are to reduce electrical energy usage by
30,000 Mwhr and natural gas usage by 100,000 GJ
annually. This presentation will cover the various projects undertaken to
achieve the energy reduction goals.