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Metso Cooking Liquor Measurement3400

Digester control

Continuous monitoring of alkali

charging and all cooking phases

Updated EA/AA concentration

every second

Reducing the Kappa variations

by up to 50%

Reducing the overall chemical

consumption

Low maintenance

Automatic scaling compensation

Continuous Lo-Solids

Batch RDH

Inline Cooking Measurement

Continuous measurement is essential for

performing e cient digester control.

The sensor of the Cooking Measurement

is constructed for direct installation into

the liquor circulation. Based on the signals

from the sensor, the Measurement provides

continuous EA/AA measurement.

Deposits on an in-line sensor can be sub-

stantial, but the sensor design of the Metso

Alkali Measurement limits the building-up

of deposits as well as the e ects hereof.

The sensor will measure conductivity from

all available ions.

When substantial changes in the composi-

tion occur, it may be necessary to perform a

1- or 2-point calibration.

However changes in the S% by 5 will result

in the EA being o by just 1%, without

corrections.

Terms of alkalinity, etc.

• Active Alkali, AA = NaOH + Na2S

as NaOH or Na2O (g/l)

• E ective Alkali, EA = NaOH + 1/2 Na2S

as NaOH or Na2O (g/l)

• Sulphidity, S% = x 100(%)

• Degree of causticizing,

C% = x 100(%)

Na2S

NaOH + Na2S

NaOH

NaOH + Na2CO

3

The sensorsThe rugged 4-electrode sensor is made of stainless

steel with the electrodes mounted on the outside

of an isolator (PTFE). Within a measuring diameter

of 200 mm (8”) diameter around the sensor elec-

trode, a current is measured between one pair of

electrodes and the potential di erence between

another pair of electrodes.

This picture illustrates how heavy the scaling can

become while still having a functional sensor due to

automatic balancing of the measuring eld. In addi-

tion the Measurement provides scaling indication.

The resultsSpeci! ed accuracy: 1–2 g/l EA Na

2O compared to

laboratory ABC tests (avg. of min. 3 samples from

each test point).

Results from a Scandinavian mill with a Metso

Cooking measurement installed in the white liquor

loading show deviations of only 0.5 g/l. Moreover

the Metso sensors require less than 8 hours service

per year.

Circulation Measuring Standard range deviation

g/l NaOH (STD)

Transfer 14–29 g/l 1.4 g/l

Trim 14–37 g/l 0.9 g/l

Upper

extraction liquor 9–13 g/l 0.5 g/l

Lower

extraction liquor 6–13 g/l 0.4 g/l

Extraction 4–13 g/l 1.0 g/l

Results from installation in various cooking

circulations.

Batch process

A mill installed a Metso Measurement in the cook-

ing circulation of each batch digester.

Metso Cooking Measurement installed in the circula-

tion pump of a SuperBatch digester.

In this way the mill was able to monitor the alkali

level and thus the consumption of alkali. When a

deviation from the standard cooking cycle oc-

curred, the mill was able to adjust the after-feed of

white liquor to the digester and thus compensate

for the variations before the cook was ! nished. This

improved the mill’s ability to reduce variations in

the Kappa number.

Continuous process

A mill installed a Metso Cooking Measurement in

the C6 trim circulation to be able to detect varia-

tions in the alkali concentration caused by plugging

in the boiler or by variations in the alkali of the

white liquor or in the pulp quality.

Metso Cooking Measurement installed in the C6 trim

circulation in a continuous digester.

With the continuous measurements and the

counteraction against variations in the alkali

concentration, the mill reported a decrease in the

Kappa-variations from ±6 to ±3.

Lo-Solids process

The Lo-Solids digester contains a number of

recirculation loops in order to remove the dissolved

wood solids from the system as well as to control

the alkali concentration by addition of white liquor.

To compensate for variations in the cooking liquor a

mill installed a number of Metso Cooking Measure-

ment to be able to adjust the white liquor feed on

an on-line basis.

Kraft pulp mill applications

Continuous Clari! ed white liquor

process Transfer circulation

Trim circulation

MCC circulation

ITC circulation

Lower counter current loop

Recirculation

Extraction

Lo-Solids Clari! ed white liquor

Recirculation

Upper extraction liquor

Lower extraction liquor

Modi! ed cooking circulation

Wash circulation

Extraction

Batch process Clari! ed white liquor

Hot black liquor

Warm black liquor 2

Hot white liquor

Cooking liquor

RDH process Clari! ed white liquor

Warm ! ll liquor

Hot ! ll liquor 1, 2, and 3

Circulation liquor

Cooking liquor

M&D sawdust Clari! ed white liquor

Pulp to the second

postdigester

For more information, contact your local automation expert at Metso.

www.metso.com/conductivity

The information provided in this brochure contains descriptions or characteristics of performance

which in case of actual use do not always apply as described or which may change as a result of

further development of the products.

An obligation to provide the respective characteristics shall only exist if expressly agreed in the

terms of contract. Availability and technical speci cations are subject to change without notice.© M

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Installation of the Metso Cooking Measurement

Metso Cooking Measurement sensor installed in a measuring pipe. It is placed in a bypass loop, thus providing

safe withdrawal of the sensor during the digester operation in case of the need for removal of any substantial

deposits.

A rack of Cooking Measurement monitors and sensors. Sensor mounted in-line.

Cooking liquor

Cooler

Sample

Measurement

Measuringpipe

Mounting across a pump

For more information, contact your local automation expert at Metso.

www.metso.com/conductivity

The information provided in this brochure contains descriptions or characteristics of performance

which in case of actual use do not always apply as described or which may change as a result of

further development of the products.

An obligation to provide the respective characteristics shall only exist if expressly agreed in the

terms of contract. Availability and technical speci cations are subject to change without notice.© M

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Metso CookingLiquor Measurements3400Speci! cations Concentration ranges: 27 preprogrammed recipes for circulating loops of batch and continuous digesters

Output: Two current outputs 4 - 20 mA for concentration, conductivity or temperature

Temperature measurement: –40 to +250°C

Display: LCD Sensor connection: Series 4000 sensors with 11-pole strip connector and MF20 cable adaptor

Local or remote measuring range selection: Four cooking set-up modes.

Control voltage: 12 – 30 V DC

HART® communication is available EnclosureMaterial: Cast aluminium, PE coated

Protection: IP67

Dimensions: 144 x 144 x 107 mm

Mounting: Panel, wall or pipe Ambient temp.: -10 to + 60°C

Storage temp.: -20 to + 70 °C

Weight: 2.3 kg

Wall Panel

Pipe

Mounting options

Pipe mounting kits

Type For pipeNo. dimension

4902 a 25-38 mm b 35-52 mm c 50-73 mm d 72-94 mm e 82-114 mm

Dimensions

Wall mounting Type 3407 Type 3417

Panel mounting Type 3408 Type 3418

Power supply Loop powered Line powered

16 – 30 V DC 85 – 265 V AC,

on mA1 6 VA

Alarm No alarm Two relays

250 V AC, 8 A

Display Non-Illuminated illuminated

For more information, contact your local automation expert at Metso.

www.metso.com/conductivity

The information provided in this brochure contains descriptions or characteristics of performance

which in case of actual use do not always apply as described or which may change as a result of

further development of the products.

An obligation to provide the respective characteristics shall only exist if expressly agreed in the

terms of contract. Availability and technical speci cations are subject to change without notice.© M

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World wide support for Metso Concentration Measurements

Go to www.metso.com/conductivity to nd your local expert