curtain coater as air knife replacement - tappi ppt.pdf · curtain coater as air knife replacement...
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Curtain Coater as Air Knife Replacement
Martin SchmidVoith Paper Inc.Appleton, WI
PaperCon 2011 Page 2522
Content
1. Introduction
2. Curtain Coating
3 Rebuild3. Rebuild
4. Results
5. Summary
PaperCon 2011 Page 2523
Sustainability –The Vision for the Future of Paper ProductionThe Vision for the Future of Paper Production
Raw material Energy Water
Maximizing the Reducing worldwide Lowering consumption Maximizing the recycling rate primary energy
consumption by halfof fresh water to less
than 1 liter per kg
PaperCon 2011 Page 2524
Long-term Demand Growth by Product Area through 2025by Product Area through 2025
Tissue Containerboards3.0
Average 1.9%/a Carton-boardsCoated
woodfree2.0
2.5
owth
[%
/a]
Coatedh i l
Uncoated woodfree
1.0
1.5
Dem
and
gro
Source: Pöyry
Uncoatedmechanical
Sackpaper
Other grades
mechanical
News-print0.0
0.5
0 20 40 60 80 100Sh f ti i 2006 [%]
90705030Share of consumption in 2006 [%]
► Above average growth rates for containerboards and cartonboards
PaperCon 2011 Page 2525
Curtain CoatingSingle MultilayerSingle - Multilayer
Single layer Double layer Multi layer
► Well proven slot die technology
► More than 30 references
► Based on the proven single layer concept
► Application of two different coating
► Slide die technology► Multiple layers
possible30 references
► For all paper and board grades
different coating formulations
► No "teapot" effect
PaperCon 2011 Page 2526
Curtain Coating
Characteristics BenefitsCharacteristics► Perfect coverage► Excellent runnability► High solids contents
Benefits► Improved printability► Less break time► Reduced drying energyg
► Ease of operation► High efficiency► No wear parts
y g gy► Wide coat weight range► Higher content of recycled
fibers► Excellent handling► Optimum CD and MD
coat weight profiles
PaperCon 2011 Page 2527
DeaerationTypical Air Content Blade Film and CurtainTypical Air Content Blade, Film and Curtain
Air contentOffset 5-12 Air contentOffset 5-12
beforedeaeration
Acceptable
BladeOffset
Roto
6-8
5-1210-25
beforedeaeration
Acceptable
BladeOffset
Roto
6 8
5-1210-25
-
air contentafterdeaeration
Film
Curtain
-
8
5-12
<0 22-5
air contentafterdeaeration
Film
Curtain
65-12
<0 12-5
6 -8
0 5 10 15 20 25 %<0.2
300 5 10 15 20 25 %<0.1
30
Only very low air contents are acceptable in curtainOnly very low air contents are acceptable in curtain coating
PaperCon 2011 Page 2528
DeaerationVacuum deaerator for Curtain CoatersVacuum deaerator for Curtain Coaters
Motor
Color inlet Vacuum pump
Cascade principle:
3 X more surface at similar outer dimensions comparedouter dimensions compared to competition
Color outletColor outlet
PaperCon 2011 Page 2529
DeaerationVisualisation of Air Coating Color on a Glass PlateVisualisation of Air - Coating Color on a Glass Plate
Before deaeration After deaeration
PaperCon 2011 Page 2530
Curtain Coating Coverage effect with Curtain TechnologyCoverage effect with Curtain Technology
Curtain Coater is capable to cover rawcapable to cover raw paper or board with low brightness!
PaperCon 2011 Page 2531
Curtain Coating Brightness vs Coat WeightBrightness vs. Coat Weight
PaperCon 2011 Page 2532
Pilot Trial Samples
Air Knife(10 parts TiO2)12 / ² K 42%
DF- Coater (10 parts TiO2)
/ ² %
DF- Coater (no TiO2)
12g/m² K: 42% 12g/m² K: 64,5% 12g/m² K: 64,5%
PaperCon 2011 Page 2533
Pilot Trial Samples
Air Knife(10 parts TiO2)
DF- Coater (10 parts TiO2)
12g/m² K: 42%
200x
12g/m² K: 64,5%
200x
reduced cloudiness
PaperCon 2011 Page 2534
Machine RebuildCurtain Coater for a Board MachineCurtain Coater for a Board Machine
Substitution of an air knife by a curtain coater
Products: several board gradesBasis weight: 230…390 g/m²Machine speed: 370…550 m/minCoat application: 12 g/m² pigment coat in the middle coatSolids content: 62 % (previously with air knife: 42 %)Width: 4850 mmStart up: May 2010
Top coat: bladeMiddle coat: curtainPre coatBase boardBack side coat
PaperCon 2011 Page 2535
Machine RebuildLayout with Air Knife Coater (Before Rebuild)Layout with Air Knife Coater (Before Rebuild)
Backside Coater 5g/m² / 45%g
Pre-Coater5g/m² / 50%
Air Knife (middle)12g/m² / 42%
Blade Coater 11g/m² / 68%
PaperCon 2011 Page 2536
Machine Rebuild with Curtain CoaterMain Scope of SupplyMain Scope of Supply
PaperCon 2011 Page 2537
Machine RebuildStart upStart-up
First color on web on June 17, 2010
Since June 18, 2010 in continuous operation
June 19 and 20: 24hrs operation without a break
Savings in drying energy immediately achieved(6 rows of IR instead of 14)
Color curtain is very stable Color curtain is very stable
Curtain formation after start is extremely fastextremely fast
PaperCon 2011 Page 2538
Machine Rebuild QualityQuality
Produced board was saleable from the 1st jumbo roll
Coverage (opacity) and gloss are better than before
Coat weight could be reduced
Flatness was much better Sheeters could run faster
Improved pick resistance Improved pick-resistance
Better printability (no mottling)
PaperCon 2011 Page 2539
ResultsCurtain Coater for a Board MachineCurtain Coater for a Board Machine
Latest results: Superior coverage and reduced cloudinessR b ildReference:
Air knife as middle coatRebuild: Curtain Coater as middle coat
Precoat: 6 g/m² rod coaterMiddle coat: 12 g/m² air knife or curtain coater, resp.Top coat: 11 g/m² bent blade
contrast enhanced
Top coat: 11 g/m bent blade
PaperCon 2011 Page 2540
ResultsCoating LayerCoating Layer
Air Knife
Curtain Coater
PaperCon 2011 Page 2541
ResultsCurtain Coater for a Board MachineCurtain Coater for a Board Machine
PaperCon 2011 Page 2542
ResultsCurtain Coater for a Board MachineCurtain Coater for a Board Machine
PaperCon 2011 Page 2543
ResultsCurtain Technology versus Air Knife CoaterCurtain Technology versus Air Knife Coater
Superior coverage and clearly reduced cloudiness
Best coating color distribution (CD + MD)
Improved visual appearance by coating layer
Si ifi t hi h lid t t (62 64 %) Significant higher solid content (62 – 64 %)
No speed limit (v > 500 m/min)
Wid t i ht (11 t 20 / ² ith t diffi lt ) Wide coat weight range (11 to 20 g/m² without any difficulty)
Very good runnability (no web break in the curtain coater since start – up).p)
PaperCon 2011 Page 2544
SummaryCurtain Coater for a Board MachineCurtain Coater for a Board Machine
Furnish cost reductionFurnish cost reductionImproved coverage allows to replace DIP by mixed waste paper
Production increase due to increased machine speedAir knife has been the bottleneck
Energy savings Increase in solids content from 42% to 62% means 50% less water to be evaporatedp
Coating cost reductionReduced pigment costs at maintained quality due to superior coverage of the coat (e.g. less TiO2 or lower coat weight, less binder)( g 2 g )
PaperCon 2011 Page 2545
MM Frohnleiten KM3 - Pictures
PaperCon 2011 Page 2546
Summary
Curtain Coating is a Green Technologygy
Energy savings due to:– Higher machine efficiency– Less drying requirements
Increased use of recycled fibers Increased use of recycled fibers due to:
– Improved machine runnability– Improved coating coverageImproved coating coverage
PaperCon 2011 Page 2547
Thank You!
PaperCon 2011 Page 2548