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Pressure Distribution
NIP CURVE
FIBRE STRUCTURE
PRESSURE CURVE
HYDRAULIC PRESSURE
CURVE
HYDRAULIC PRESSURE
CURVE FELT
1 2 3 4
1
1
2
2
3
3
4
4
ROLL
PAPER WEB
FELT
ROLL
FABRIC OR
VENTA-NIP
PRESSURE
DISTRIBUTION CURVE
TIME OR NIP LENGTH
THICKNESS OF PAPER
WEB IN THE NIP
COMPRESSION
CAP FORCES
TWO-PHASE FLOW
WATER TRANS
MECHANISMS
HS
SATURATED
THICKNESS
PHASE
HS
HMIN
HMIN
HOUTH
IN
POINT OF
MAX DRYNESS
PRESS DISTRIBUTION IN NIP ZONE
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Plain Press nip (unsaturated)
SHEET
FELT
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Plain Press nip (saturated)
SHEET
FELT
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Suction Press
SHEET
FELT
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Grooved Press
SHEET
FELT
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Double felted Double grooved press
SHEET
FELT
FELT
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ENP Extended Nip Press
Press shoe
Press sleeve
Pistons Top
press
roll
Press sleeve
Supporting beam
Blade
Press shoe Top press
roll
Yankee dryer
Lub/Cooling oil shower
Clamping ring
Static supporting
beam
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ENP Extended nip press
Press
sleeve
Pistons
Press
shoe
Static
supporting
beam
Top press roll
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L 5-6xL
ENP Extended nip press
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ENP press impulse vs. standard
-80 -70 -60 -50 -40 -30 -20 -10 -0 10 20 30 40 50
0,5
1,0
1,5
2,0
2,5
3,0
Nip Distance (mm)
Nip
Pre
ssu
re (
Mp
a)
3,5 Standard nip
ENP
90 kN/m
240 kN/m
90 kN/m
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ENP trade marks
• ENP (Beloit) • ENP-C (Beloit) • NipcoFlex (Voith) • TissueFlex (Voith) • Sym-Belt (Metso)
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Location of conditioning system
Location of suction boxes, showers and guide rolls gives rise to risk of splashing on sheet.
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More suitable felt run.
Location of conditioning system
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Tension & guide devices
: The angle of wrap of the felt across the guide roll must be at least 25°.
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The distance a + b must be at least equal to the width of the felt. The distance b must be at least 1/3 of the width of the felt
Tension & guide devices
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Press configurations
Pre-pressing in a solid press
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Air bleed in a suction press
Press configurations
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Single-felted soft tissue machine with a long suction zone in the first hot press
Press configurations
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: Suitable run with blind-drilled first press roll.
Press configurations
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Recommended felt-sheet run for venta nip press in high speed machines.
Press configurations
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Suitable felt run in double-felted press.
Press configurations
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Adjustable guide roll before the nip in a double-felted press.
Press configurations
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The pick-up angle against the wire should be sharp so as to give a satisfactory transfer. a illustrates an unsuitable felt run.
Press configurations
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Different sheet runs when pressing pulp sheets against plastic wire.
Press configurations
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Effect of outgoing felt angle on adhesion of sheet to felt.
Press configurations
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Blowing before second press in a double press with a centre roll
Press configurations
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Felt run after grooved press to prevent water throw-off on felt.
Press configurations
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Suitable felt run after first suction hot-press (with short suction zone) to prevent water throw-off to felt
Press configurations
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Press fabric run after 2nd press
Felt and wire run in a second press
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Outgoing angle and double felted nip
A- The Sheet accompanies the bottom felt after the nip B- The Sheet accompanies the top felt after the nip
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Separation and dewatering of top felt between two presses.
Outgoing angle and double felted nip
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Recommended alteration to felt angles in high speed newsprint machines.
Outgoing angle and double felted nip