The warm touch of metal belt calendering

More production with less raw materials Mika Viljanmaa

Metal belt calender

History Technology & Process Results References Case example Summary

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Agenda

Metal belt calendering history

1996-2001 Invention, preliminary studies and tests 2001 Start-up of small pilot (width 270 mm, speed 600 m/min) 2003 Start-up of 2nd pilot, readiness for full scale pilot trials (width 550 mm, speed 1000 m/min) 2003-2005 Pilot tests with several board and paper grades carried out with promising results 2006 Start-up of 1st ValZone at M-real Simpele BM 3, Finland 2007 Start-up of 2nd ValZone at Zhuhai S.E.Z. Hongta Renheng Paper Co., Ltd BM 2, China 2008 Start-up of 3rd ValZone (confidential) 2009-2011 Start-up of 4th ValZone, Shandong Bohui, China and 5th, IPSP22 and 6th SUN Paper 23, China 3

Metal belt calender

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Historical pictures

Metal belt calender

History Technology & Process Results References Case example Summary

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Agenda

Metal belt calender

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Technology

Metal belt calender

• One-meter-long machine-direction calendering zone

• Smooth metal belt and smooth thermo roll

• Both metal belt and thermo roll can be heated

• Symmetrical process

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Operating principle

Speed: 600 m/min

Metal belt calender

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Video – Three phases of extended calendering zone

Metal belt calender

• Long dwell time - Dwell time 30…200 ms - 100 x longer than soft or hard nip - 4…15 x longer than shoe nip

• Effective plasticization - No need for high pressures - No need for additional moisturizing

• Very long calendering zone - ~1000 mm

• High thermal energy - Steel belt surface 80...170 °C - Thermo roll surface 80...170 °C

• Low nip pressure - 0.2 MPa with metal belt - 1...10 MPa with profiling nip load - Linear load between 10…70 kN/m

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Process is based on: Technical features:

DC roll

Thermo roll

Paper web

Metal belt (heated)

Long calendering time and effective plasticization

Metal belt calender

• Longest running time so far 684 days • Average running time of all board metal beltcalenders last removed

belts 394 days • Wearing and fatigue do not limit belt lifetime.

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Current calculations for belt lifetime

Metal belt calender

History Technology & Process Results References Case example Summary

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Agenda

Metal belt pre calendering Coated boards

ValZone metal belt calender

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Very low macro scale roughness

Fiber scale Formation scale

metal belt

soft nip hard nip

shoe nip base paper

RM

S =

Roo

t Mea

n S

quar

e ro

ughn

ess

[µm

]

Wave length [µm]

Metal belt calender

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Uniform z-direction coat weight distribution

Calcium intensity distribution by Laser-induced plasma spectrometry

Metal belt calender

• FBB 230 g/m² (Zhuhai S.E.Z. Hongta BM 2)

• Topography pictures of coated carton board

• 3 coating layers

• Total coat weight 30 g/m²

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Excellent topography for final product

Hot hard nip Metal belt

• Topography variations strike through even after three coating layers

• Excessive gloss variations

• Even and flat surface • Fewer gloss variations

Metal belt calender

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Stiffness bulk increase after the process optimization

Triple coated FBB

32 %

8 %

Metal belt calender

Same quality and printing area with 6% less fibers

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FBB mill, Finland

11 October, 2012

Grammage [g/m²]

Thickness [mm]

Bulk [cm³/g]

Specifications before rebuild

Specifications after rebuild

Change (%)

270

0.450

1.67

255

0.450

1.76

- 6

0

+ 6

Metal belt calender

• Premium quality board without speed limitations • Removes existing bottlenecks, such as Yankee cylinders and wet stacks • Provides possibilities for increasing drying capacity

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Enables production increase of 20 - 40%

ValZone Released / added drying capacity

Before

After

Limited / unutilized drying capacity

Metal belt calender success story at M-real Simpele

226.000 tpa (2008)

300.000 tpa (2011)

170.000 tpa (2005), 85.000 tpa (1970 start-up)

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Metal belt final calendering Uncoated woodfree paper

Metal belt calender gives +3…5 % higher bulk for WFU at same Bendtsen roughness level

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0

50

100

150

200

250

300

350

1,10 1,15 1,20 1,25 1,30 1,35 1,40 1,45 1,50Bulk, cm³/g

Ben

dtse

n, m

l/min 2-nip soft

Metal belt calender

+ 3 %

+ 5 %

Bulk - Bendtsen

Feel roughness measurement by KCL • Conventional surface roughness measurements doesn’t predict how

the surface feels like. • In the analysis, paper samples are ranked according to hand-feel

smoothness by a trained panel by KCL touch&feel research group • On the same Bendtsen level the metal belt calendered papers give

remarkably smoother impression.

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Metal belt calendered surface feel smooth

Metal belt calendered surface feels smoother “silky touch” of surface

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0

20

40

60

80

100

120

0 50 100 150 200 250 300 350Bendtsen, ml/min

Feel

roug

hnes

s

2-nip soft

Metal belt calender

soft calender 50 ml/min ~ metal belt calender130 ml/min soft calender 170 ml/min ~ metal belt calender 270 ml/min

Bendtsen – Feel of roughness (KCL)

Feel roughness vs Bendtsen roughness

Metal belt calendered Observation:

• When calendered with metal belt calender, the paper can be left up to 100 ml/min rougher (Bendtsen) compared to softcalendered — and it still feels as smooth to finger .

Soft nip calendered Explanation:

• Where other calendering methods compress the whole paper structure, ValZone mainly levels down the high ”hilltops” of paper topology due to long low-pressure stabilizing thermodynamic treatment. This plateau is felt by fingertips as a smooth surface.

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Bendtsen roughness (ml/min)

Metal belt calender gives +7…18 % higher bulk for WF at same feel roughness level

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0

20

40

60

80

100

120

1,10 1,15 1,20 1,25 1,30 1,35 1,40 1,45 1,50Bulk, cm³/g

Feel

roug

hnes

s

2-nip soft

Metal belt calender

+ 7 %

+ 18 %

Bulk - Feel of roughness (KCL)

Feel roughness correlates with large scale topography

Height variation (4-10 mm) - Feel of roughness (KCL)

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Metal belt calender

History Technology & Process Results References Case example Summary

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Agenda

Metal belt calender

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Reference list

Start Speed (m/min)

Width (mm) Company

2011 1600 7300 Sun Paper PM23

2010 900 5630 Shandong Bohui BM 7, China, FBB

2009 700 6400 Stora Enso Kaukopää BM 4, Finland, LPB

2008 900 4580 IPSP22

2007 600 4350 Zhuhai S.E.Z. Hongta BM 2, China FBB, (LPB)

2006 800 4080 M-real Simpele BM 3, Finland FBB

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Metal belt calender

History Technology & Process Results References Case example Summary

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Agenda

Metal belt calender

Due to Metal belt calenders bulk and stiffness improvement the basis weight for the milk carton can been reduced, for instance, from 280 g/m2 to 265 g/m2. Thereby, how many milk cartons more can be produced? Production rate of 300 000 t/a?

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Case: Raw material saving

Source of the picture: http://www.bvwaste.ca/files/milk-cartons.jpg

Metal belt calender Case: Raw material saving

What can be done with 728 million milk cartons?

before ValZone Grammage of carton, g/m2 280 265

Production capacity, m2/a 1 071 000 000 1 132 000 000 Number of milk cartons / a if 1 m2 equals 12 milk cartons 12 857 000 000 13 585 000 000

Difference in milk cartons / a 728 000 000

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Metal belt calender Case: Raw material saving

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• Lined-up cartons extend 173 000 km

• 4,3 times around the Earth

• More than 17 times from St. Petersburg to Vladivostok

That much raw material is wasted when not calendered with Metal belt calender!

35 Source of the picture: http://www.bvwaste.ca/files/milk-cartons.jpg

Metal belt calender Case: Raw material saving

Metal belt calender

History Technology & Process Results References Case example Summary

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Agenda

Metal belt calendering

High bulk and stiffness • lower basis weight • reduced raw material costs Even and stable macroscale topography • good base for coating • even coat weight distribution • even topography after coating • excellent printability Increased production • Increased drying capacity by removing bottlenecks (e.g. yankee,

wet stack)

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Benefits for coated paper and board makers

Metal belt calendering

Higher bulk and higher stiffness • lower basis weight • lower raw material cost Excellent surface properties • smoothness in macro scale • feel of smoothness ~ ”silky

touch” High quality paper can be made on-line • large operation window • two-sidedness control

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Benefits for uncoated paper and board makers

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DATE/TITLE/AUTHOR

Thank You !