MACHINE CLOTHING FOR TWIN WIRE FORMER

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MACHINE CLOTHING FOR TWIN WIRE FORMER AN
EXPERIENCE IN MYSORE PAPER MILLS By
K. Rajaganapathy
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• BRIEF DESCRIPTION OF MYSORE PAPER MILLS (MPM)
• PAPER MACHINE 1 COMMISSIONED IN THE YEAR 1938
• PAPER MACHINE - 2 COMMISSIONED IN THE YEAR 1954
• PAPER MACHINE - 3 COMMISSIONED IN THE YEAR 1964
• PAPER MACHINE 4 (TWIN WIRE FORMER) COMMISSIONED
  
• IN THE YEAR 1981
• MPM HAS THE INSTALLED CAPACITY OF 75000 TPA
  NEWSPRINT
• 35000 TPA OF WRITING AND PRINTING PAPER.
• IN PM 4 NEWSPRINT OF PINK AND NATURAL SHADE ARE
  MADE

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• PULP FUNRNISH
• COLD SODA REFINER MECHANCIAL PULP (CSRMP) - 60
• HARD WOOD CHEMICAL PULP (CP 2) - 24
• IMPORTED SOFT WOOD CHEMI THERMO MECHANICAL PULP
  (CTMP)
• / THERMO MECHANICAL PULP (TMP) 12
• IMPORTED BLEACHED SOFT WOOD SULFATE PULP (BSWSP)
  - 4

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PULP FREENESS CSRMP PULP 180 240 o
CSF CP 2 PULP 380 400 o CSF CTMP /
TMP 120 140 o CSF ICP 400 450 o
CSF STUFF BOX FREENESS 180 200 o
CSF HEAD BOX FREENESS 80 120 o CSF
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• APPROACH FLOW SYSTEM
• FOUR STAGE COUNTER CURRENT CENTRICLEANER SYSTEM
• DECULATOR FOR REMOVING THE AIR AIDED BY VACUUM
  PUMPS
• PRESSURE SCREEN BEFORE THE HEAD BOX IN TWO
  STAGES
• PRIMARY AND SECONDARY AND THE SECONDARY REJECTS
• PASSED TO VIBRATING SCREEN.
• HEAD BOX IS CONVERFLOW HEAD BOX WITH TUBE BANK,
  STILLING
• CHAMBER AND CONVERFLOW ELEMENTS (LEXAN SHEETS)
  TO
• CREATE MICRO TURBULANCE

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CONVERFLOW HEAD BOX
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BEL BAIE II FORMER
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• PRESS SECTION IS OF TRI NIP CONFIGURATION
• DRYER IS 4 SECTION WITH INDIVIDUAL DRIVE
• STEAM AND CONDENSATE IS CASACADING SYSTEM
• THREE NIP CALENDER
• REELER FOR 6.8 METERS DECKLE
• MACHINE SPEED OPERATING RANGE 560 MPM TO 630 MPM

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INTRODUCTION Forming fabrics development in
general and selection process in particular with
respect to Mysore Paper Mills will be discussed
in detail. It varies from mills to mill and
conclusion is arrived on their experience and
suitability to the mills. Cleaning of Fabric is
also addressed.
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• BEL BAIE II FORMER
• It is a vertical former stock is pumped
  upwards between the wires.
• More water mark on the paper in the initial
  years.
• Vacuum deflector gave rise to more water marks on
  the paper
• Less dwell time in the forming zone due to
  shorter former length
• First pass retention is 50 - 55 given by the
  supplier.
• Ceramic tiles in the forming zone for water
  drainage.
• Water drainage through centrifugal action,
  tension of wires and drainage elements.
• No outside wash roll
• No mount hope roll

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• General consideration for fabric selection
• Dimensional stability of the fabric over its life
  time
• Good drainage index (DI)
• Good fiber support index (FSI)
• Sheet forming top surface should be supporting
  the free water drainage at the same time good
  sheet formation
• The fabric should easily help in releasing and
  transferring the formed sheet to the next section
• The fabric should allow in return run to clean
  properly by mechanical means like high pressure
  water shower.
• The fabric shall not soil and clog in the wide
  furnish mix.

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• Able to retain and give good fist pass retention.
• Machine side should be able to withstand wear and
  tear of stationary and rotating elements.
• It should not leave mark on the paper.
• Water spots and wire pick marks should be nil
• Drive load of the section should not increase
  drastically,
• In twin wire former particular for Bel-Baie II
  it should give characteristic double jet drainage
• Able to withstand sudden machine trip and related
  problems
• It should maintain square run in wide range of
  operating speed.
• Finally and most important should give targeted
  production.

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In the Bel-Baie II former the wires are
categorized as backing wire (21.80 X 7.55) and
backing wire (17.83 X7.55). The backing wire
helps in drainage and formation of the web and
forms a true twin wire configuration. Whereas
the forming wire does formation of sheet,
drainage of water, and transferring the formed
web to next section.
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Since from the inception, way back in the year
1981 the technology was limited and people using
the synthetic wires were few. The available best
was single layer wire. In MPM also conventional
single layer fabric was used in forming and
backing wire position.
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• Problems with single layer fabrics
• Less dimensional stability.
• Poor guiding
• Prone to damages
• Power failure and tripping of the machine wire
  getting damaged.
• Waviness of the wire
• Wire used to move front or back during on machine
  caustic wash.
• Without mount hope roll wire getting creased was
  very common.
• Lesser open area compared to multilayer fabrics

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• Advantages of Multilayer fabrics
• Dimensional stability is excellent.
• More open area
• Damages are very less during power failure and
  machine tripping.
• Guiding is good very rarely gives problem.
• In spite of the above advantages the initial
  problems with multilayer fabrics were
• More water marks on paper
• Drive load used to go up
• Cleaning the fabrics requires high pressure
  needle jet showers

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Backing w ire used in Paper Machine 4 Single
Layer Fabric in the period 1981 - 2006
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Backing Wire used in Paper Machine 4 Double
layers Fabric from2006
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Forming wire used in Paper Machine 4 Single
Layer Fabric in the period 1981 2001
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Forming wire used in Paper Machine 4 Double
layer fabrics from 2001
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From the above data it is very clear the
double layer fabric given more tonnage per
fabrics than single layer fabrics At the same
time indigenous wires also given equally good
result as far as tonnage per fabrics is
concerned.
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Cleaning of Fabric Cleaning of fabric is effected
in two ways, continuous mechanical cleaning and
chemical cleaning Very high pressure needle
shower form the part of mechanical cleaning under
this Nozzle diameter 1 mm Shower angle against
the fabric run for better cleaning and to avoid
damage to fabrics. Distance between nozzle and
fabric approximately 50 to 150 mm. Needle shower
should not split before hitting the fabric for
good cleaning. Shower oscillation complete
coverage of fabric preferably overlapping of
nozzle. Higher the fabrics tension lesser is the
damage to fabric. Water pressure is around 35 to
40kgs/cm2
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Chemical cleaning is done whenever the machine
is stopped. 5 of caustic solution is
sufficient to give a good cleaning effect. Now a
days sulfamic acid is used widely to clean the
fabric. The forming fabric is prone to damages
since it comes in contact with stationary
drainage elements and vacuum zones. The damages
like holes on fabric happen during the machine
start up and stoppage. The VHP showers water
opening and closing is interlocked with fan pump
to avoid fabric damages.
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Conclusion It is imperative to use the new
technological development to ones own advantage.
Sometime the new technological teething problems
are to be addressed effectively in co-operation
between fabric manufactures and end user. The
advantages of new technology should be mutually
beneficial to fabric manufactures and end user.
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Acknowledgement We would like to thank MPM
management for permitting us to publish the
article and thank all those who helped us in
preparation of this article.
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• LITERATURE
• A reliable method to predict fabric life
  Michael J Mcmohon Vol .80 No.3 Tappi Journal
• Forming fabric design and development by Jim
  Matheson Paper maker Oct 1994.
• The evaluation and selection of forming fabric
  theory and applications Vol.62 No.4 Tappi April
  1979.
• Analysis of return machine clothing yields
  operating insights improvement Pulp and Paper
  1996.
• Cleaning multilayer forming fabric Ron Green and
  E.Mal Condon July 1992 Tappi Journal.

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THANK YOU
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