Zeta DataTM Technology

1
Zeta DataTM Technology

• For
• Laboratory Process Development
• and
• On-Line Monitoring and Control
• of
• Papermaking Wet End Chemistry

2
Introduction

• Paper Chemistry Consulting Laboratory, Inc.,
  doing business
• as Paper Chemistry Laboratory, Inc., (PCL) was
  incorporated
• in New York State in 1978.
• PCL supplies Dynamic Paper Chemistry Jars and
  Zeta Data
• Instrumentation, as well as consulting services.
  PCLs
• dedication to advancing the state of the art,
  enables us to
• recommend the most cost-effective process
  chemistry
• technology.

3
Zeta DataTM Laboratory Zeta Potential Instrument

• The Lab Zeta DataTM Instrument
• forms a fiber pad to measure the properties of
  the entire furnish.

4
The Lab Zeta DataTM Measures

• Zeta Potential, mV
• Conductance, µS/cm
• Temperature, oC
• Drainage, ml
• Data is output to a printer.

5
Zeta DataTM On-Line Zeta Potential System

• Improve Quality and Productivity
• with On-Line Monitoring and Process Chemistry
  Control

6
The On-Line Zeta DataTM Measures

• Zeta Potential, mV
• Conductance, µS/cm
• Temperature, oC
• Drainage, ml
• Data is transmitted via 4-20 mA outputs.

7
Zeta DataTM Measurement Chamber
Rinse Tube
Vacuum / Discharge Tube
Drainage Probe
Rinse Nozzle
Screen
Electrodes (2)
To Manifold
8
Principle of Operation

• The Zeta DataTM System draws stock through a
  screen to form a pad.
• While pumping white water through the pad, the
  electrical charge, or "streaming potential" is
  measured.
• Measure the conductance across the pad.
• Measure the temperature.
• Measure the total volume of fluid which passes
  through the pad during the measurement cycle as
  drainage.
• Software applies the measured data to the
  Helmholtz- Schmoluchowski equation, to calculate
  the zeta potential, expressed in millivolts.
• The measurement cycle takes less than two
  minutes.

9
On-Line Zeta DataTM Construction

• Only the most reliable components are selected
  which meet international performance standards.
• The mounting frame and manifold are constructed
  from stainless steel.
• Electronics are isolated in a water tight (Nema
  4) fiberglass enclosure.
• A vortex cooler controls the electronics
  enclosure temperature and humidity.

10
ON-LINE ZETA DATATM FRONT PANEL
11
Front Panel Indicators

• The Zeta Data front panel consists of the
  following diagnostic lights
• Normal Status
• POWER on
• VACUUM NORMAL on
• SYSTEM FAULT off
• VACUUM FAULT off
• PRESSURE LOW FAULT off
• CHAMBER FULL FAULT off
• CYCLE FAULT off

12
On-Line Zeta DataTM Interface

• The On-Line Zeta Data is designed to be
  connected to a Distributed Control System (DCS).
• Starting and stopping the Zeta Data system is
  controlled by a digital input line originating
  from the DCS.
• System normal/fault status is reported via one
  digital output line to the DCS.
• Data values are supplied using four 4-20 mA
  isolated outputs.

13
On-Line Zeta DataTMUtility Requirements

• Electrical 115/220 Volts A.C., 3 amps
• Instrument Air 80 - 100 PSI at 12 scfm
• Rinse Water 60 PSI, 40o C 5o

14
Sample Flow
SAMPLE INLET
15
Rinse Water Flow
16
Maintenance

• Field experience since 1989, including the
• deployment of third generation On-Line
• Zeta DataTM Technology, enables attainment
• of the high level of up-time necessary for
• on-line process control.
• Maximum up-time is obtained by close
• adherence to the following maintenance
• schedule.

17
On-Line Zeta DataTM Maintenance Schedule
KEY ü Inspect þ Clean , Repair or Replace
18
Repeatability Test Results
The data in the following graph was taken during
the repeatability part of the final test of an
On-Line Zeta DataTM . Zeta Potential averaged
-13.7 mV, with a standard deviation of 0.65mV.
Drainage averaged 58.8 ml, with a standard
deviation of 2.8ml.
19
Typical Repeatability Test Results
20
THE MICROPARTICULATE PROCESS

• Consideration should be given to basing virtually
  all tissue, towel, paper and board making
  chemistries on the microparticulate process.
• It affords the best balance of retention and
  formation.
• The figure represents research done by Pierre of
  Centre Technique, which shows the relationship
  between retention and formation for several
  different chemistries.
• The cationic starch and colloidal silica curve
  exemplifies the excellent balance between
  formation and retention which can be obtained
  with the microparticulate process.
• Zeta Potential control is essential to process
  optimization at minimum chemical cost.

21
THE EFFECT OF VARIOUS RETENTION AIDS ON
FLOCCULATION AND RETENTION
22

• The following graph represents a series of
  fifteen
• laboratory experiments, using an alkaline fine
• paper furnish. Increasing amounts of a cationic
• polyamine were added, followed by a fixed amount
• of microparticle, reflecting the paper mill
  practice of
• adding a fixed amount of microparticle and making
  
• an upstream feed rate adjustment of cationic
  polymer.
• The data demonstrates that microparticulate
  process
• optimization requires controlling the zeta
  potential
• within a narrow range.

23
Alkaline Fine Paper Furnish
Maximum Drainage
2mV
24
The following graph represents a series of
fifteen laboratory experiments with the
Laboratory Zeta Datatm. The furnish is 0.5
bleached kraft HWDSWD to which was added 25
dry, precipitated calcium carbonate (PCC).
Increasing amounts of a high molecular weight
polyDADMAC were added, followed by .3 bentonite.
This reflects the paper mill practice of adding
a fixed amount of microparticle after the
screens and making an upstream adjustment of the
feed rate of cationic polymer in order to balance
and optimize the process. We have earlier shown
that a "clean" system, ie containing no anionic
trash, is optimized at a small, positive zeta
potential. It is interesting to observe that
the presence of a larger amount of dry,
precipitated PCC shifts the optimum to a slightly
more positive value.
25
Alkaline Fine Paper FurnishHigh PCC Loading
Maximum Drainage
5 mV
26

• Optimizing process chemistry enables operation of
• the paper machine at uniform high levels of
  quality
• and productivity.
• The purpose of process chemistry development is
  to
• optimize retention and/or drainage at minimum
• chemical cost. It is easily accomplished by
  altering
• chemical feed rates to maintain maximum drainage,
  by
• operating at the optimum zeta potential,
  parameters
• which can be monitored and controlled by use of
  the
• On-Line Zeta DataTM.

27
Process Chemistry
28
The following graph represents a series of about
thirty-six experiments using an alkaline fine
paper furnish comprising 30 coated broke and 70
bleached kraft tap water at 0.5 consistency.
Chemicals are added in the following order
Nalco 7607 polyamine in increasing amount, 0.1
AKD cationic emulsion, 0.25 cationic starch, and
0.15 colloidal silica. This reflects the common
practice of adding a fixed amount of
microparticle after the screens and making an
upstream feed rate adjustment of cationic
polymer. The vertical arrow points to the
simultaneous peaks in drainage, sizing and
strength and the horizontal arrow points to the
final zeta potential, about 5mV.
29
Process Chemistry Optimization
30

• The following graph represents a PCC-filled,
  AKD-sized process, which additionally uses a
  scavenger, cationic starch and colloidal silica.
  Increasing amounts of cationic scavenger have
  been added to incrementally increase the zeta
  potential. Note that retention (ash), drainage,
  sizing, and Scott Bond are all at maximum in the
  zeta potential range demarcated by the vertical
  lines, 2 to 6mV zeta potential.
• A positive optimum zeta potential makes sense
  because all commercial microparticles are
  anionic, and require a cationic stock for
  substantivity. When one adds nominally 0.15 to
  0.3 colloidal silica or bentonite, it is an
  insufficient amount to reverse the charge.

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• There are three key conclusions
• 1. Both physical and process properties
  maximize in a narrow zeta potential range, and
  degrade rapidly as the zeta potential increases
  or decreases from optimum.
• 2. An On-Line Zeta Data should be installed at
  the headbox, and the optimum zeta potential
  maintained by altering a chemical feed rate to
  stay at maximum drainage. This is of critical
  importance because it coincides with maximum
  retention and the best obtainable physical
  properties. One should initiate closed loop
  process control within 60 days of installation,
  and the Zeta Data installation will pay for
  itself in a few months.
• 3. The optimum is never reached and maintained
  by accident. Product quality and productivity
  are predictably problemated when the process is
  out of control, as yours presently may be.

32
Process Chemistry Optimization Experimental
Series No. 3
33
Recycle Newsprint Lab Methodology

• Thick stock taken from the Blend Chest is mixed
  with white water to a consistency of 0.5, and 2
  calcium carbonate is added.
• The decrease in zeta potential from the -40 mV
  range to the low teens can be attributed to the
  calcium ion, Ca.
• The addition of 1.5 alum causes a negative spike
  in zeta potential.
• The addition of PEI (polyDADMAC would be
  equivalent), to obtain a zeta potential of 5 mV,
  more than doubles the drainage, from slightly
  under 4 ml to 8 ml.
• The addition of a microparticle in the form of
  0.3 bentonite (colloidal silica and others are
  equivalent) causes a drainage spike approaching
  16 ml, a several hundred per cent improvement
  over the original 3-4 ml.
• Use of the Lab Zeta Data provides a clear picture
  of cause and effect inter-relationships of wet
  end chemicals.

34
Process Development of Recycle Newsprint with the
Lab Zeta DataTM
35
The Effect of Anionic Trash

• Observations
• The dirtier the system,
• the lower the drainage.
• the less efficient the chemical performance.
• the more cationic chemical required to maintain
  optimum Zeta Potential.
• Conclusion
• It is more efficient to remove anionic trash in
  the
• pulp mill than to precipitate it in the wet end.

36
The Effect of Anionic Trash

• The following graph represents three series of
  experiments with 0.5 bleached HWDSWD at
  increasing levels of anionic trash, in the form
  of anionic ground calcium carbonate slurry 2,
  25 and 50 GCC. Increasing amounts of polyamine
  are added, to a zeta potential of 5 mV, followed
  by a fixed amount of microparticle.

37
The Effect of Anionic Trash