Recycled Fiber Management The Key To Better Paper Quality. kajaani

kajaani Metso Automation Field Systems Division Kehräämöntie 3 , P.O. Box 177 FIN-87101 Kajaani Finland Tel. +358 20 483 120 Fax +358 20 483 121 Nor...
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kajaani

Metso Automation Field Systems Division Kehräämöntie 3 , P.O. Box 177 FIN-87101 Kajaani Finland Tel. +358 20 483 120 Fax +358 20 483 121

North America 3100 Medlock Bridge Road, Suite 250 Norcross, GA 30071 USA Tel. +1 770 446 7818 Fax +1 770 242 8386 Latin America Av. Central 181, Chácaras Reunidas 12238-430 São José dos Campos SP Brazil Tel. +55 12 3935 3500 Fax +55 12 3935 3535 Asia Pacific 501 Orchard Road #05-09 Wheelock Place 238880 Singapore Tel. +65 673 552 00 Fax +65 673 529 55 www.metsoautomation.com

B48 42.1_EN © Metso Automation, 8/2002 Printed on recycled paper manufactured from 100% post consumer waste.

Europe Levytie 6 , P.O. Box 310 FIN-00811 Helsinki Finland Tel. +358 20 483 150 Fax +358 20 483 151

Recycled Fiber Management The Key To Better Paper Quality

PulpExpert measures automatically: • Consistency • Brightness, color, light scattering • Dirt count • ERIC • Fiber length • Tensile • Freeness from up to 8 sampling points

The Key To Better Paper Quality From Recycled Fiber

Ash

ultimate confirmation of pulp quality based

The ash content of the process is indicative

on laboratory standards; brightness, ERIC,

of the quality and ratio of the raw materials

dirt count, light scattering and color

used, and the operation of flotation,

from its automatically prepared and

screening and cleaning. The kajaaniRMi

measured hand sheets.

provides accurate and continuous

PulpExpert measures the size, shape and

measurement of ash content in addition to

contrast of each individual dirt spec in the sample and classifies the results in userselectable classes.

kajaaniCORMECi Brightness and ERIC measurements

Improvements in process stability, better

Consistency

control of the mechanical and chemical

In many cases, total consistency is the single

processing and effective control of the raw

most important measurement in the entire

consistency so that the operator can easily

material components all provide

line. As an example, total Cs of the first

find the right set points for process

tremendous economic benefits. The result

flotation stage is of crucial importance, and

parameters.

is lower chemical and energy consumption,

the effect of any consistency variation at

better machine runnability and improved

this point will be seen in all subsequent

end product quality. In recycled fiber

stages, possibly even amplified. Metso has

Brightness, residual ink and dirt

production, key measurements include

mechanical, optical and microwave

The brightness of recycled pulp is

Recycled fiber, or waste paper, is

consistency, ash, brightness, residual ink,

transmitters, each optimized for recycled

dependent on lignin content, ink and dye

increasingly being used as a raw material

dirt count, pulp quality and chemical

fiber applications that together with the

concentration as well as ash and other non-

of papermaking processes, even for many

properties. The relative importance of each

PulpExpert absolute consistency

fiber constituents. The kajaaniCORMECi can

"new" paper and board grades. Newly

measurement depends on the process and

measurement provide continuous and

continuously measure in-line the separate

developed measurement technology and

on the end use of the pulp.

accurate information.

process control can have a great impact on the quality of the finished product.

effects of lignin, ink (Effective Residual Ink kajaaniRMi

Concentration) and dye. The PulpExpert

kajaaniMCAi

Ash content measurement

analyzer with online sampling provides

Microwave consistency transmitter

PulpExpert measures automatically: • Consistency • Brightness, color, light scattering • Dirt count • ERIC • Fiber length • Tensile • Freeness from up to 8 sampling points

The Key To Better Paper Quality From Recycled Fiber

Ash

ultimate confirmation of pulp quality based

The ash content of the process is indicative

on laboratory standards; brightness, ERIC,

of the quality and ratio of the raw materials

dirt count, light scattering and color

used, and the operation of flotation,

from its automatically prepared and

screening and cleaning. The kajaaniRMi

measured hand sheets.

provides accurate and continuous

PulpExpert measures the size, shape and

measurement of ash content in addition to

contrast of each individual dirt spec in the sample and classifies the results in userselectable classes.

kajaaniCORMECi Brightness and ERIC measurements

Improvements in process stability, better

Consistency

control of the mechanical and chemical

In many cases, total consistency is the single

processing and effective control of the raw

most important measurement in the entire

consistency so that the operator can easily

material components all provide

line. As an example, total Cs of the first

find the right set points for process

tremendous economic benefits. The result

flotation stage is of crucial importance, and

parameters.

is lower chemical and energy consumption,

the effect of any consistency variation at

better machine runnability and improved

this point will be seen in all subsequent

end product quality. In recycled fiber

stages, possibly even amplified. Metso has

Brightness, residual ink and dirt

production, key measurements include

mechanical, optical and microwave

The brightness of recycled pulp is

Recycled fiber, or waste paper, is

consistency, ash, brightness, residual ink,

transmitters, each optimized for recycled

dependent on lignin content, ink and dye

increasingly being used as a raw material

dirt count, pulp quality and chemical

fiber applications that together with the

concentration as well as ash and other non-

of papermaking processes, even for many

properties. The relative importance of each

PulpExpert absolute consistency

fiber constituents. The kajaaniCORMECi can

"new" paper and board grades. Newly

measurement depends on the process and

measurement provide continuous and

continuously measure in-line the separate

developed measurement technology and

on the end use of the pulp.

accurate information.

process control can have a great impact on the quality of the finished product.

effects of lignin, ink (Effective Residual Ink kajaaniRMi

Concentration) and dye. The PulpExpert

kajaaniMCAi

Ash content measurement

analyzer with online sampling provides

Microwave consistency transmitter

1 Pulping

Removing ink and dirt. Achieving quality targets. Step by step,

Pulping is the first critical step in recycling and deinking. It determines how well the fibers are separated from each other, which has a subsequent impact on yield. If contaminants are not well enough separated from the fiber, removing them will increase fiber losses. On the other hand, severe pulping conditions may reduce the size of contaminant particles and thus complicate their subsequent removal from the pulp. Ink separation from fiber is primarily

4

accomplished in the pulper, and the ease of ink removal in the first deinking stage is mainly determined by the pulping conditions. Consistency at the pulper outlet is one of the most important control parameters which influences the operation of the entire deinking plant. The kajaaniMCAi flow-through consistency transmitter, based on microwave technology, is independent of pulp type making it ideal for

3

recycled applications. Chemical addition to the pulper can be controlled by measuring peroxide residual with kajaaniPOLAROXi in the recirculation water and controlling caustic addition for maximum effect.

2

2 Coarse and Pre-screening Coarse screening removes large foreign items from the pulp.

8

1

Screening and cleaning are important steps, as these remove most the remaining non-fibrous contaminants including stickies. In the early stages of the process there is still quite an amount of unwanted material present, and the flow-

7

through kajaaniMCAi is the best solution for consistency measurement. Brightness measured here or even earlier after the pulper gives an idea of what to expect after deinking and can help by optimising raw material usage when higher brightness waste paper is available.

3 Flotation The kajaaniCORMECi brightness transmitter can, by using different wavelengths, be used to separately resolve the influences of lignin, ink and dye. By measuring the Effective Residual Ink Concentration (ERIC), the degree of success of ink removal can be determined and adjustments made for

5 6

better efficiency. This will include chemical dosages to the pulper and flotation as well as optimizing conditions in subsequent cleaning and screening operations. Consistency should be controlled at the inlet of the flotation cell, to stabilise pulp quality and to ensure stable process operation. Consistency and ash content measured with kajaaniRMi at the inlet and outlet of the flotation cell indicate filler losses inside the cell. Ash content can be optimised in two alternative ways. For some paper grades no ash is accepted, while for others, fillers in the deinked pulp should be retained as long as the ratio can be kept constant.

RCF Process Measurements

1 Pulping

Removing ink and dirt. Achieving quality targets. Step by step,

Pulping is the first critical step in recycling and deinking. It determines how well the fibers are separated from each other, which has a subsequent impact on yield. If contaminants are not well enough separated from the fiber, removing them will increase fiber losses. On the other hand, severe pulping conditions may reduce the size of contaminant particles and thus complicate their subsequent removal from the pulp. Ink separation from fiber is primarily

4

accomplished in the pulper, and the ease of ink removal in the first deinking stage is mainly determined by the pulping conditions. Consistency at the pulper outlet is one of the most important control parameters which influences the operation of the entire deinking plant. The kajaaniMCAi flow-through consistency transmitter, based on microwave technology, is independent of pulp type making it ideal for

3

recycled applications. Chemical addition to the pulper can be controlled by measuring peroxide residual with kajaaniPOLAROXi in the recirculation water and controlling caustic addition for maximum effect.

2

2 Coarse and Pre-screening Coarse screening removes large foreign items from the pulp.

8

1

Screening and cleaning are important steps, as these remove most the remaining non-fibrous contaminants including stickies. In the early stages of the process there is still quite an amount of unwanted material present, and the flow-

7

through kajaaniMCAi is the best solution for consistency measurement. Brightness measured here or even earlier after the pulper gives an idea of what to expect after deinking and can help by optimising raw material usage when higher brightness waste paper is available.

3 Flotation The kajaaniCORMECi brightness transmitter can, by using different wavelengths, be used to separately resolve the influences of lignin, ink and dye. By measuring the Effective Residual Ink Concentration (ERIC), the degree of success of ink removal can be determined and adjustments made for

5 6

better efficiency. This will include chemical dosages to the pulper and flotation as well as optimizing conditions in subsequent cleaning and screening operations. Consistency should be controlled at the inlet of the flotation cell, to stabilise pulp quality and to ensure stable process operation. Consistency and ash content measured with kajaaniRMi at the inlet and outlet of the flotation cell indicate filler losses inside the cell. Ash content can be optimised in two alternative ways. For some paper grades no ash is accepted, while for others, fillers in the deinked pulp should be retained as long as the ratio can be kept constant.

RCF Process Measurements

Brightness Loss Caused by Ink in Pulp

Process Variables in Deinking

The Effect of Ink at Different Wavelengths

Comparison of Lab Results and kajaaniCORMECi Reading

0.18 Ash Cs, % (inlet of 2nd flotation stage)

0.14 0.1 0.06 0

5

10

15

20

Time, hours

0

5

10

15

20

Time, hours

70 Level of 2nd flotation stage

69 68

65

100 ppm increase in ERIC will decrease pulp brightness by about 2.5 ISO

Brightness (deinked pulp to PM)

60

The ink has strong absorption at wavelengths over 700

55 50

(e.g. from 62 to 59.5%). To counter this brightness loss with bleaching

Laboratory residual ink content (ERIC) vs. inline sensor ERIC measurement.

nm and causes a drop in reflectance index. The effective 0

5

10

15

20

Time, hours

we should increase fiber brightness from 62 to 68%. Brightness increase

residual ink test method, ERIC, is based on the absorption of infrared light.

with DIP is roughly only 50% of the increase which we can achieve with

Normal process variation in flotation. Ash consistency

virgin pulp in bleaching.

measured in inlet and Brightness measured on outlet.

7 Before Pulp Storage Prior to pulp storage, brightness, residual

Measurements to the paper machine serve

Optimized Solutions for Your Process

ink, and dirt count will provide valuable

as the final quality assurance and in some

We hope that this process description has

information on quality to the paper

mills can be used for blending operations

served as an introduction to the possibilities

6 Dispersion and Post Flotation

machine. Overall trends can be identified

before the paper machine to achieve

of good RCF measurements that will

quickly and adjustments made to the

required strength or brightness targets.

provide the desired final product quality at

Brightness, residual ink and dirt count can

process. In extreme cases, decisions to

be measured with PulpExpert. Conditions

recirculate out of specification pulp or treat

Brightness Monitoring in DIP Process

environmental impact. There are many

should be controlled to achieve the

it differently can be made with confidence

with the Inline Brightness Sensor

modifications, differences and

maximum dispersed ink removal.

before it contaminates the storage tower.

improvements that can be made to the

Additionally kajaaniCORMECi can also be

As well as deinked pulp brightness and dirt

example process we have used. Please

used for a continuous brightness and ink

count, PulpExpert can measure other pulp

contact your local Metso Automation

paper product is below 60 – 65% ISO,

content monitoring to control these final

properties such as strength and color. If a

resource to find the optimum configuration

adding peroxide into the pulper is often

deinking steps. Ash content is very

final reductive bleaching stage is in use,

for your process as well as the insight we

enough. For higher brightness multistage

important as minimal variation is needed

kajaaniCORMECi can provide slow feedback

have gained in other applications.

bleaching is needed, including both

to ensure good runnability on the paper

correction to the hydrosulfite stage control

Feed consistency to screening is important

oxidative and reductive bleaching

machine.

with the continuous brightness, residual

to ensure the maximum removal of

chemicals. Brightness and residual ink can

contaminants including dissolved solids

be measured on-line using the

and remaining stickies. Consistency control

kajaaniCORMECi brightness transmitter and

SmartPulp Valmet

is normally done in two stages using

used for a feedforward control strategy. The

blade consistency

SmartPulp consistency transmitters with

brightness loss caused by ink in pulp is hard

transmitter

blades specially designed for this

to counter by bleaching alone because the

application. In addition to dirt count,

pulp brightness has to be much higher to

PulpExpert's absolute consistency

counteract optical properties of the residual

measurement can provide continuous

ink. Stable pulp brightness after the

tuning for superior accuracy even with

bleaching tower is thus very difficult to

varying pulp components.

achieve if the ink content varies a lot.

5 Bleaching If the brightness requirement for the final

4 Cleaning and Fine Screening

ink and L-a-b color measurements.

8 Final Quality

the most economical level while minimizing

Pulp brightness at different stages of DIP process; 1. After first flotation, 2. After second flotation and 3. After hydrosulphite bleaching – final brightness. 10 % more magazine paper in the raw material means 1 % higher brightness.

Brightness Loss Caused by Ink in Pulp

Process Variables in Deinking

The Effect of Ink at Different Wavelengths

Comparison of Lab Results and kajaaniCORMECi Reading

0.18 Ash Cs, % (inlet of 2nd flotation stage)

0.14 0.1 0.06 0

5

10

15

20

Time, hours

0

5

10

15

20

Time, hours

70 Level of 2nd flotation stage

69 68

65

100 ppm increase in ERIC will decrease pulp brightness by about 2.5 ISO

Brightness (deinked pulp to PM)

60

The ink has strong absorption at wavelengths over 700

55 50

(e.g. from 62 to 59.5%). To counter this brightness loss with bleaching

Laboratory residual ink content (ERIC) vs. inline sensor ERIC measurement.

nm and causes a drop in reflectance index. The effective 0

5

10

15

20

Time, hours

we should increase fiber brightness from 62 to 68%. Brightness increase

residual ink test method, ERIC, is based on the absorption of infrared light.

with DIP is roughly only 50% of the increase which we can achieve with

Normal process variation in flotation. Ash consistency

virgin pulp in bleaching.

measured in inlet and Brightness measured on outlet.

7 Before Pulp Storage Prior to pulp storage, brightness, residual

Measurements to the paper machine serve

Optimized Solutions for Your Process

ink, and dirt count will provide valuable

as the final quality assurance and in some

We hope that this process description has

information on quality to the paper

mills can be used for blending operations

served as an introduction to the possibilities

6 Dispersion and Post Flotation

machine. Overall trends can be identified

before the paper machine to achieve

of good RCF measurements that will

quickly and adjustments made to the

required strength or brightness targets.

provide the desired final product quality at

Brightness, residual ink and dirt count can

process. In extreme cases, decisions to

be measured with PulpExpert. Conditions

recirculate out of specification pulp or treat

Brightness Monitoring in DIP Process

environmental impact. There are many

should be controlled to achieve the

it differently can be made with confidence

with the Inline Brightness Sensor

modifications, differences and

maximum dispersed ink removal.

before it contaminates the storage tower.

improvements that can be made to the

Additionally kajaaniCORMECi can also be

As well as deinked pulp brightness and dirt

example process we have used. Please

used for a continuous brightness and ink

count, PulpExpert can measure other pulp

contact your local Metso Automation

paper product is below 60 – 65% ISO,

content monitoring to control these final

properties such as strength and color. If a

resource to find the optimum configuration

adding peroxide into the pulper is often

deinking steps. Ash content is very

final reductive bleaching stage is in use,

for your process as well as the insight we

enough. For higher brightness multistage

important as minimal variation is needed

kajaaniCORMECi can provide slow feedback

have gained in other applications.

bleaching is needed, including both

to ensure good runnability on the paper

correction to the hydrosulfite stage control

Feed consistency to screening is important

oxidative and reductive bleaching

machine.

with the continuous brightness, residual

to ensure the maximum removal of

chemicals. Brightness and residual ink can

contaminants including dissolved solids

be measured on-line using the

and remaining stickies. Consistency control

kajaaniCORMECi brightness transmitter and

SmartPulp Valmet

is normally done in two stages using

used for a feedforward control strategy. The

blade consistency

SmartPulp consistency transmitters with

brightness loss caused by ink in pulp is hard

transmitter

blades specially designed for this

to counter by bleaching alone because the

application. In addition to dirt count,

pulp brightness has to be much higher to

PulpExpert's absolute consistency

counteract optical properties of the residual

measurement can provide continuous

ink. Stable pulp brightness after the

tuning for superior accuracy even with

bleaching tower is thus very difficult to

varying pulp components.

achieve if the ink content varies a lot.

5 Bleaching If the brightness requirement for the final

4 Cleaning and Fine Screening

ink and L-a-b color measurements.

8 Final Quality

the most economical level while minimizing

Pulp brightness at different stages of DIP process; 1. After first flotation, 2. After second flotation and 3. After hydrosulphite bleaching – final brightness. 10 % more magazine paper in the raw material means 1 % higher brightness.

kajaani

North America 3100 Medlock Bridge Road, Suite 250 Norcross, GA 30071 USA Tel. +1 770 446 7818 Fax +1 770 242 8386 Latin America Av. Central 181, Chácaras Reunidas 12238-430 São José dos Campos SP Brazil Tel. +55 12 3935 3500 Fax +55 12 3935 3535 Asia Pacific 501 Orchard Road #05-09 Wheelock Place 238880 Singapore Tel. +65 673 552 00 Fax +65 673 529 55 www.metsoautomation.com

B48 42.1_EN © Metso Automation, 8/2002

Europe Levytie 6 , P.O. Box 310 FIN-00811 Helsinki Finland Tel. +358 20 483 150 Fax +358 20 483 151

Printed on recycled paper manufactured from 100% post consumer waste.

Metso Automation Field Systems Kehräämöntie 3 , P.O. Box 177 FIN-87101 Kajaani Finland Tel. +358 20 483 120 Fax +358 20 483 121

Recycled Fiber Management The Key To Better Paper Quality