Permi Online Air Permeability Analyzer

Permi by© ACA Systems all rights reserved1

Online Porosity Measurement

and Control

Permi by© ACA Systems all rights reserved

“Porosity is the best indicator for the balance

of pulp quality and machine settings”

2


Advantages

The very fast machine direction measurement enables a new kind of

control of paper and paperboard processes.

Increase from 576 ton/day up to 648 ton/day (12,5 %) in production

of liquid board.

Speed increase of cigarette paper machine from 300 m/min to 400

m/min (25 %).

100 000 euros savings/a when chemical (retention and defoaming

agent) proportioning was optimized by Permi.

3


System configuration

4

Measuring UnitControl Unit


Measuring head

Durable and low friction coating against paper web.

Outer vacuum ring with a separate vacuum control

prevents errors caused by the air pressure from the

moving web.

Using the optimised sensor geometry PERMI can

recalculate several porosity values according to

different standards.

Grade independent.

Accurate online readings, which help optimise

machine setting, furnish mix and especially get

faster grade changes with minimum broke.

5

Vacuum ringMeasurement slot


Measuring head 2

6

Vacuum ring

(outer circle)

Measurement slot

(inner circle)


Installation pictures

7



8



9



10


Measuring range

Bendtsen, ml/min 10 – 20 000

Coresta 1 – 10 000

Gurley, s 6 000 – 1

Others are available on request

11


Process control and Permi

Key benefits of Permi

High sampling rate, 500 per second.

Continuous online operation.

Wide measuring range.

Best correlation to laboratory results.

Controlled vacuum levels.

Quick change of measuring method.

Minimum calibration on grade changes – short grade changes.

Reduces the need for laboratory testing.

12



Key benefits of Permi (continues)

Splendid real time information for refining control.

Optimizing base paper porosity for coating.

Quicker grade change - less broke.

Improved vacuum control in wire section.

Better wet-end chemistry management.

Superb control of calendering for uncoated papers.

Better wire and felt management.

Improved roll grinding management.

13



Monitoring of fast porosity variation

Reasons for variation Refining variation

Control of deculator

Proportioning of retention agent

Consistency of headbox

Control of vacuum box

Control of vacuum rolls

Foil angles

Dosage of antifoaming agent

14



Increased porosity (decrease in Gurley seconds) due to a small addition of uncoated broke

Very small changes in the broke

levels can have a big effect on paper

porosity (increasing or decreasing). In

this case addition of uncoated broke

has increased porosity

15



Uncoated broke vs. Porosity

16

Porosity [ml/min]

Broke [m³/h]



Couch vacuum and online porosity

Papermakers know that changes in couch

vacuum correlate quite well with changes in

final paper porosity.

The graphs from a kraft paper machine show

that high couch vacuum results in low porosity

(mirror curves).

However, sometimes the correlation is not

perfect due to variations in couch solids, press

and dryer section parameters as well as in

surface sizing and calendering when applicable.

17



refining

retention

vacuums

pH levels

foil angles

deaerators

hitting points

starch content

pulping process

consistency of head box

adding of coated broke

adding of uncoated broke

adding points of retention agent

retention agents as well as fillers

etc.

18

Some examples of use of Permi results to optimization work


Refining and Porosity

Refiner control systems

The most common refiner control is

Specific Energy Control. This cannot

compensate any changes in raw

materials or processes after refining.

Slightly better are CSF-control and

couch roll control. However, there are

so many processes after forming

section having effect on paper quality

and porosity that the only correct way

is to measure the final paper before

calendering and adjust or control

refining according to that.

19



Wet end control with Permi

Fibres , refining, fines, fillers and wet end chemistry have effect on drainage, flocculation and retention.. All these effect on porosity, which is a good measure of paper quality.

Formation is a measure of small scale variations. Porosity measures variations as well as the level of paper quality.

By measuring paper porosity online it is possible to control wet end including raw materials, refining, wet end chemistry and wire section performance to get better paper quality..

20



Adding refining energy will

decrease the size and number

of pores in the paper.

Fiber network tightening in the

refining is based in the

increase of fines content and

fiber bonded area, thus

resulting in a lower air

permeability level.

21

Lumiainen, J., Refining of chemical pulp, Papermaking Science and Technology, Book 8, Stock

Preparation and Wet End, Paulapuro, H. (Ed.),Fapet, Jyväskylä, CD-Rom (v.11.01).



Conventional Control of Refining SRE control of refiners cannot decrease pulp quality variations

With on-line porosity measurement this can be corrected!

22

SRE = Specific Refining Energy

Pe = Effective Power, Pt = Total Power, Po = Idle Power

m = Fibre flow (Bone Dry)



Freeness, porosity and refining

It has been interesting to note that the load distribution

between two softwood kraft refiners in series has effect on

porosity.

Specific energy consumption (SEC) in the first refiner was

reduced as much as it was increased in the second refiner.

Total SEC was constant as well as freeness (CSF).

However, paper porosity decreased about 25%. This shows

that CSF control cannot be correct in all situations.

It seems that only fines content has effect on freeness while

also internal fibrillation of fibres and fibre flexibility have

effect on porosity.

23

CSF

Porosity

Refiner loads (kWh/t):2.

1.



Example of filter paper machine

A very small change in

refining control can be

clearly seen in the porosity

measurement. The units of

porosity numbers are l/m2/s.

24



Refining control with porosity In series refining fibres are stiffer in the first refiner. If the load is too high, fibre cutting

and fines formation will increase. This decreases freeness and drainage on the wire.

In the second (and third refiner) fibres are more flexible and specific edge load can be higher without fibre cutting and fines formation. However, internal fibrillation will advance more and more flexible fibres compensate the binding power of fibre fines.

Same porosity can be achieved with higher CSF when using increased loading order. Total energy can be saved, drainage on the wire is increased and lower headboxconsistency can be used to get better formation even if the fibres are longer and paper strength is better.

Loading shares between refiners is only one example how online porosity can be utilised to optimise refining. This would not be possible by using freeness measurement, which mostly reflects fines content.

25



High porosity sack kraft paper

Porosity control must be accurate for a high porosity sack kraft paper to reach the optimal combination of tensile strength and porosity.

26



Energy savings Customer informed, that they get 6,25 % energy savings, when they used Permi

results to control refiners. Savings came, because pulps were not refined too much.

Production: > 50 000 t/a

Average energy consumption (before): 160 kWh/t

Price of kWh: 0,06 €/kWh

Price of consumption per year: 480 000 €

Savings using automated control of refiners: 6,25 %

Price of savings: 30 000 €/a

Speed: > 900 m/min

Product: fine papers

27



TEA and Refining

Refining is always a compromise

between porosity and strength

properties.

Quick filling of valve sacks require

Gurley porosity between 5 and 10

seconds. This is the range, where TEA

(Tensile Energy Absorption) and tensile

drop very fast.

It is important to have a good control on

porosity to be able to make these

grades with acceptable combination of

the critical properties.

28



Feedback Porosity for SEC* control

29

SEC Correction

Pulp from storage chest

Permi set pointfrom Operator

Controller

Pulp to mixing chest

Permi OnlinePorosity Analyser

SEC set point from Operator

SEC set point selection

SEC controller loop

Permi supervisory

predictive control

can give remote

set-point to SEC-

control about 6

times per hour or

faster

+/-

± 15 kWh/t

Dry paper web

*SEC = Specific Energy Consumption (kWh/t pulp)


Fillers, Fines and Porosity

Retention and porosity

There is a clear correlation

between retention and porosity.

Stabilizing long term retention

variations would reduce paper

quality variation.

30



Filler Type and Porosity

31



Filler Type and Porosity

Plate-like fillers, such as kaolin and

talc decrease bulk and porosity.

Carbonates such as PCC and GCC

increase bulk and porosity.

32



Effect of Filler on Porosity

Coarse carbonate fillers increase porosity,

but fine clay decreases it.

By using two fillers it could be possible to

control porosity of paper and filler content

independently.

33



Fibre fines and porosity

More fines at the edges – better Scott bond and lower porosity (more fibre bonding).

34


Drying and Paper Porosity

Filtration and Porosity

35

Liimatainen, H., et. All; Furnish

Consepts, Metso Paper

Technology Days 2003, Lahti, June 10

– 12, pp. 18 – 29.



Vacuum in Forming Roll and Porosity

36



Porosity and drying shrinkage

It is easy to see that on the left picture (freely dried) porosity is higher than on the right (restrained drying).

37

Freely dried paper Restrained drying shrinkage

Picture: Fapet, Paper Drying


Wet pressing and porosity

Wet pressing has a strong effect on the properties of paper. The press geometry, rolls and their covers, felts and linear pressure combinations must be selected to conform to the running speed and the paper grade to be produced.

38

Metso Paper



Dry Content and Porosity with Shoe Press and Roll Press

39

KnowPap 4.0 (2002)



Press Draw and Porosity

A high press draw is not only question of runnability but also paper quality is lower when low porosity is needed.

Porosity measurement is also a good tool for evaluating what is a too high press draw

40


Formation and Porosity

Normalized ß-formation as a function of paper openness measured as Bendtsen air

permeability for the reference (kraft 60% and TMP 40%), DIP-based, and mechanical

virgin pulp-based furnishes.

41

Bad

Good



Generally the porosity is low when the formation is good.

42

Good base paper

Bad base paper

Ari Puurtinen:MULTILAYERING

OF FINE PAPER WITH 3-

LAYER HEADBOX

AND ROLL AND BLADE GAP

FORMER, Espoo 2004



43


Coating and Paper Porosity

Porosity and Coating Coverage

Dense sheet – small penetration of coating color and good coating coverage and gloss.

Porous sheet – deep penetration of coating color and poor coating coverage and gloss. Misting problems in film coating.

44Forsström et al. TAPPI Coating Conference, 2002

http://www.kcl.fi/news/link12004/link12004s4.html



Coating Coverage in Film Coating

Due to nip pressure coating coverage depends on porosity not on roughness.

45

U.Forsström et al. Tappi Coating

Conference, 2002

http://www.kcl.fi/news/link12004/link1

2004s4.html



Coat Weight and Gloss vs. porosity in Film Coating

Due to pressure penetration coat weight increases as porosity increases and gloss decreases. In blade coating gloss increases, when coat weight increases.

46

U.Forsström et al. Tappi

Coating Conference, 2002

http://www.kcl.fi/news/link12004/

link12004s4.html



Porosity versus Opacity

Opacity of Coated Paper (on-line coater)

Porosity of Base Paper

47



Coating and web breaks

It seems that higher porosity predicts web break in a blade coater.

48

Porosity, s Basis Weight, gsm

BREAK BREAK


Total Process Control with Porosity

Porosity control before headbox

Porosity decreases with: More refining

More low freeness mechanical pulp

More coated broke (normally) or DIP

More fibre fines (better retention)

Less anionic trash (less hydrophobic material)

More hardwood pulp

Less softwood kraft pulp

More wet end starch

Less fillers or more platelike fillers (talc, delaminated clay)

Less air in stock

49



Porosity control on paper machine

Porosity decreases with: Higher grammage

Better formation (usually)

Good retention

Slow drainage

More wet pressing

Less press draw or drying shrinkage

More surface size

More film forming size (PVA, CMC)

Less surface size penetration

Pigmented surface size

50



Reasons and effects of low porosity

51

High internal bond

Low press to dryer drawWet Pressing

Good formation

Low air content

Good refining Good bonding

Corrugating medium

Low oil absorption

No pinholes

Good runnability

No print through

Dense sheet

Rotogravure printability

Offset printability

Low silicone pick-up

Limit: Set-off in CSWO

Low porosity

correlates with:Root cause:

Final benefit of low

porosity:



Process Control by Permi

52



Constant porosity – Consistent quality

Papermakers know that final porosity of cigarette, filter and sack papers is very

important but also printability and runnability properties of printing papers correlate

well with final paper porosity.

Most on-line instruments measure and control only one paper property. In addition to

final paper porosity, which is an important property for some paper grades, Permi is a

universal analyzer of paper quality for most paper grades due to the fact that almost

all process parameters have a clear effect on porosity.

On the other hand, porosity correlates with almost all physical paper properties. If

porosity is constant, paper process performs well and paper quality is consistent.

53



Porosity and Paper Quality

54

Decreased

bulk

Better

formation

Lower

caliper

Lower

stiffness

Better

ply bondBetter

smoothness

Less print-

through

Less

pin holes

Higher

opacity

Better

print gloss

Lower ink

absorption

Increased

basis weight

Increased

moistureDecreased Porosity

More fibre

bonding

Higher

strength

Lower tear

strength

Lower light

scattering

Lower opacity

and brightness

Less

dusting

Lower ink

demand

Lower

fluting



Process parameters increasing porosity

55

Higher Porosity

Lower

retention

Less broke

Lower fibre

fines content

More pin holesLower fibre

bonding

Softer windingDecreased wet

pressing

Coarser fibre

type

Less surface

size

More

carbonate

fillers

Less platey

fillers

Less wet end

starch

Less reject in

screening

Reduced

refining

Wet end

chemistry

Pulsating

drainage

More

shrinkage at

web edges

Reduced

calendering

Higher press

draw

More

flocculation

Higher air

content



Advantages of single-point measurement A normal scanner covers only a tiny fraction of the web area. With a scan speed

of 0.5 m/s, web width of 10 m and web speed of 25 m/s web travels 500 m during

one scan. It is impossible to separate cross directional and machine directional

variations from a scanned measurement. However, there are separate CD and

MD controls, which cannot work very well in the wavelength range of 1 to 100

seconds.

This range is the most common problematic area related to variations in the

approach flow and short circulation of the paper machine. These variations are

mainly fluctuations in stock consistency but there can be other sources of

variation like raw material mixture, fines content or chemical condition of the

stock.

With a fast Permi porosity analyzer it is possible to improve the process so that

basis weight and moisture controls work better and the fast peak-to-peak

variation, which cannot be seen in the scanner measurement, is lower and thus

runnability is better.

56



Advantages of single-point measurement One of our customers is using our sensor in a scanning system and our fixed

point Permi analyzer in another paper machine. They told us that they have done

quite a lot of research work with the both units and at least in their case the MD-

profile measurement with the Permi helps them much more than the CD-profiles.

The reason is that if there are short trend machine direction changes, they cause

wrong CD-profiles with the scanning sensor even though the sensor itself makes

the measurements correctly. They told that the same happens with all other

scanning sensors, too (grammage, ash etc.). They also told that the CD-porosity

profile changes in their machine only if they change a felt or a wire.

This customer uses always the Permi results to control the paper machine and

they told that with light weight grades they run the paper machine following only

the MD-porosity profile. From the Permi readings they can see how well the wet

end and the head box are working. They also pointed out that the quality of their

papers is better, but especially the runnability of the paper machine is nowadays

better than before the Permi installation.

57



Typical CD and MD variation in porosity

Usually, there is a lot of CD

variation, but it is quite stable

from reel to reel. This could

be measured in the

laboratory and corrected if

possible.

Machine direction variation of

reel averages seems to be in

this case about ± 15 ml/min

(>10% range). This could be

corrected by using online

porosity measurement.

58



Wet end control According to Metso Paper the most important measurements for wet end process control are

formation and porosity. With these on-line measurements the optimum running window can be found.

59

TARGE

T AREA

Porosity, ml/min

Fo

rmation

, %

Determining process

operation point

Control action rules:

• Headbox slice opening

• Former vacuums

Quality set points:

• Formation

• Porosity

Controls

Dewatering

Dryness

after press Porosity

Formation

Process Paper



PM wet end control

60

Metso’s opinion of the most important measurements to control wet

end process are moisture after presses, formation and porosity.



Effect of increasing actuator set point in film coated paper

61

Actuator increase Dry weight Moisture Caliper Porosity Coat weight Gloss

Ba

se

Pa

pe

r Headbox Dilution

Press section steam

Water spray

Calender nip pressure

Co

ate

d Rod pressure

SC steam

SC nip pressure

= main actuator for each property


Total Process Control with Permi

Porosity is an overall measure of process performance. Porosity

measurement is like Freeness in stock preparation. When porosity is

stable process is performing well.

Permi is an excellent analyzer before surface sizing and coating.

Permi not only shows the history of the paper web but also predicts

how good coverage of size or coat weight can be achieved in the

following process.

Film coating and cases where the positive effects should be made with

a minimum coat weight are well suited for Permi.

When porosity is low, size or coating penetration is reduced and the

effect of coating on the paper surface is better. This is important when

basis weight is low, coating colour cost is high or when coating low

brightness base paper e.g. linerboard.

62



Process Optimization and Paper Quality Fast porosity measurement is the best link between process performance and total paper quality.

Stable porosity is a good guarantee of well working process and consistent paper quality.

63

Tensile

Bulk

Formation

Caliper Stiffness

Scott Bond Roughness

Print throughPin holes Opacity

Print gloss Ink demand

Basis weight Moisture

Drainage

Fillers

Wet pressing

Retention

Fibres

Press draw

Air content

Chemicals

Flocculation

Refining Screening

Web shrinkage

Calendering Winding

Permi


Paper Grades and Permi

Sack paper

Filter paper

Office paper

Medical paper

SC base paper

MG-kraft paper

Cigarette paper

Release papers

Envelope paper

Bank note paper

Photo base paper

Corrugated medium

Saturating base paper

Base paper for coating

Base paper for siliconizing

Uncoated calendered papers

64


Board Grades and Permi

Plasterboard

Gypsum board

Special boards

Release boards

Cigarette board

Graphical boards

Food service board

Base board for coating

Liquid packaging board65


Board Grades and Permi

Linerboards and Closed Water System

Closed water system is problematic because there is lot of fine material

circulating in the process.

Sometimes there is more fines in the sheet and the properties are

different. It is important to know the porosity because more fines means

more fibre bonds and better strength properties.

One is able to control fines better and learn about the process what is

causing variation of fines. Things like retention, web breaks, broke

amount, OCC quality, wire suctions wet pressing, condition of wires

and felt etc. all have effect on porosity and fines content.

66



Base Paper for Coating

Coaters need to have the correct porosity of base

papers, because solids content of coating color is

low. With a high amount of water there is a risk

that too much binders migrate with water into the

base paper (poor water retention).

Binder migration results in lower surface strength

and mottled printing product.

Due to pressure penetration coat weight increases

in film coating, when porosity increases. However,

coating coverage and paper gloss decrease.

67



Photo and Printing Papers

The printing quality of papers as well as the

runnability of printing machines depends on the

porosity of the paper.

If the porosity is too high, printing ink is

absorbed too deep into the paper structure and

the print quality is not sharp.

If the porosity is too low, printing ink stays on

the paper surface and the result may be

smudgy.

68



Office Papers

One of the most used office paper is copy

paper. Porosity has a good correlation to the

runnability of office papers in printers, faxes and

copying machines.

If porosity is too low there is risk for multifeed,

which can even damage the machine. If

porosity is too high, paper machine runnability

and printing quality may suffer.

69



Corrugating Medium (Fluting)

The corrugating medium is the fluted

layer of corrugated board made for

package and container boxes.

The porosity level of corrugating

medium correlates with refining and

has a good correlation to the board

strength, which is one of the most

important factors of packing materials.

70

Fluting



SC Papers SC papers (supercalendered uncoated magazine and

cataloque papers) must a have dense structure which

means a low air porosity. Porosity has a good

correlation with the printability of SC grades. Porosity is

one of the most important quality factors to be

measured.

The final porosity is a combination of the base paper

porosity and supercalendering process. The porosity

after supercalendering is very low, which means that

the accuracy of the porosity measurement must be

extremely good.

The porosity of the uncalendered base paper is

reasonable high and easy to measure.

71



Newsprint Porosity has a good correlation with the

printability of newspaper grades.

If the MD porosity profile is stable the runnabilityof printing machines will be excellent. The porosity (=structure of paper) variation is the main reason for the runnability problems in printing machines caused by newspapers.

When the MD porosity profile is stable, the runnability of a paper machine will be fine, too, there is a certain possibility to increase a speed of the paper machine.

72



Sack Paper

If permeability of sack paper is

too low air cannot pass the

walls of a paper when pouring

powder into a sack.

If the porosity is too high

strength problems may appear,

for instance, a sack filled with

heavy powder can break.

73



Cigarette Papers The porosity has an influence on the temperature of combustion of

cigarette papers, which has an effect on the tar level of a cigarette.

The porosity has an influence on the taste of cigarettes, on dust content and on temperature of the burning process. Air must also pass the walls of the paper to dilute and cool the smoke of a cigarette.

Easy and fast on-line measurements help to keep the porosity of cigarette paper on the correct level and save time and money in grade changes.

The biggest problem is to keep the small scale variation as low as possible.

The most used measuring standard is Coresta. The usual air permeance of cigarette paper is 30 – 50 Coresta (about 25 – 15 Gurley seconds).

74



Security Papers

The quality requirements of security papers

are high. The porosity is an important factor

in controlling the process.

The porosity of bank notes must be correct

for proper function of automatic counting

machines. If the porosity is too high air

cannot pass between the bank notes and

the counting machine may take two (or

even more) bank notes at the same time.

75



Filter Papers

Depending on the porosity of the

paper, very small particles can be

trapped.

The price of filter papers can be very

high, so it is important to keep the air

porosity constant to avoid broke and

to keep the total efficiency of the

production high.

76


Permi versus competitors

Permi system configuration Air is vacuumed through the web with constant pressure

Flow rate is continuously measured

77

Electronic flow rate signal

Permi

Control

BoxEjector

Preset

leakage

vacuum

Air flow

Paper web

Preset measuring vacuum

Vacuum

controller

Sensor head and measuring

device are integrated

DCS

Two porosity

signals



78

Measured

volume

100 ml

Leakage

vacuum

~ 1 kPa

Measuring

vacuum

~ 1 kPa

Paper web

Air flow

Long pneumatic distance between sensor

head and measuring device

100 g

Preset

leakage

vacuum

Preset

measuring

vacuum

Paper web

Air flow

Flow meter

Ejector

Vacuum

controller

PERMI measures air flow Multiperm, Microperm and Porolog

measure time



Comparison Permi vs. conventional on-line porosity analyzers

79

Conventional on-line porosity analyzers

One measurement/

1 000 m

One measurement/

1 000 m

Web speed 1 200 m/min, Porosity 50 Gs

Dead time

600 m

80 000 measurements/ 3200 mPermi

Permi• One measurement 2 ms - 0,04 m

• Continuous measurement

• 80 000 measurements - 3200 m

Dead time

600 m

Conventional on-line porosity analyzers

• One measurement 50 s - 1000 m

• Dead time 30 s - 600 m

• Two (2) measurements - 3200 m



80

Permi:

Normally one calibration is enough for one paper machine. If 70 grades => one (1) calibration.

Recalibration in every 2nd year.

Measuring time 2 ms.

Changes in roughness or web tension or speed do not have affect the results.

0.95 correlation or better to lab analyzers.

Competitors:

Usually every grade needs own calibration. If 70 grades => 70 calibrations.

Recalibration in every week.

Measuring time 5 ... 120 s

Changes in roughness, or web tension or speed have influence in results.

Poor correlation to lab analyzers without frequent recalibration.



81

Permi:

Normally one calibration is enough for one paper machine. If 70 grades => one (1) calibration.

Recalibration in every 2nd year.

Measuring time 2 ms.

Changes in roughness or web tension or speed do not have affect the results.

0.95 correlation or better to lab analyzers.

Competitors:

Usually every grade needs own calibration. If 70 grades => 70 calibrations.

Recalibration in every week.

Measuring time 5 ... 120 s

Changes in roughness, or web tension or speed have influence in results.

Poor correlation to lab analyzers without frequent recalibration.


Users’ Experiences

The shortest pay back periods have been 4 – 8 weeks even though the Permi replaced a competitor’s unit.

The accurate and high-speed results have helped customers to control refining, shorten grade changes, control and minimize quality problems.

Kruger Wayagamack has informed that they have managed to improve both quality of papers and runnability of paper machine with the on-line porosity analyzer made by ACA Systems.

82



Energy savings up to 10 Kwh/ton with better control of refining.

The personnel of Stora Enso Varkaus Mill voted the Permi to be the best investment in 2004-2005.

100 000 euros savings/a when chemical (retention and defoaming agent) proportioning was optimized by Permi.

Increase from 576 ton/day up to 648 ton/day (12,5 %!) in production of paper board when the proportion of fines was optimized by Permi (if drying is a bottleneck).

83



15 % average shortening in grade changes.

Over 3 % increase in production in a Finnish LWC machine.

5 % increase in production in a Finnish office paper machine.

84



Permi On-Line Porosity Analyzer gives us very reliable online information

for controlling the refiners, and the fines content in our furnish. It has

helped us optimize the paper quality and mechanical fiber treatment

consistently, and save energy in refining.

The online information provided by Permi – together with some other activities - has also helped us shorten grade change time by 15 - 20 %.

- Mill Manager Juha Kovanen, Savon Sellu, Finland

85



We noticed, that we have sometimes very unstable porosity level. Things, which can swing the porosity, are the amount of fines, the refining, the unstable pH-level, the levels of tanks and very many others. But we can’t solve this kind problems, if we haven’t an equipment like the Permi.

Permi can give us very interesting and reliable possibility to control and optimize for example the pulping processes.

I believe that every process has many things, which are swinging the stability of process and which can be seen and solved with the Permi.

Grammage and moisture measurements are important ones, but with the fast porosity measurement one is able to make profit!

I ordered the Permi too late!

- Production Manager Seppo Karine, Stora Enso Imatra PM 1

86



With Permi, we have reduced energy consumption in refining, and seen a reduction in product waste.

Permi allows us to maintain the product quality

After two years of having Permi on our paper machine, it is not possible to operate without it!

Porosity feedback allows us to control refining intensity on each paper grade, and the operators follow it all the time.

- Production Manager Luc AUBRIOT, Ahlstrom La Gere, France

87


Users’ Experiences, Engine Filters

The measurement values of our essential parameters of porosity and air permeability are showing very convincing results.

Permi produces a continuous and very clear picture of the sheet.

It allows us to anticipate changes before each parent reel change, so it is a very powerful tool in process management.

- Production Manager Yves MELOTTE, Ahlstrom Malmédy, Belgium

88


Correlations

On-Line Permi vs. Lab. in MD LWC Base Paper

89


Correlations

Average 15 % - 20 % shorter Grade Changes.

One linear calibration makes possible to follow grade changes in real time.

90


Correlations

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Correlations

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Results by Ahlstrom Glassfibre, Karhula, Finland

Permi by© ACA Systems all rights reserved100 Thank You for Your Attention!

"Know structure of your paper in order to better run your

machine!"