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Emco Controls A/S
Høgevej 6
DK- 3400 Hillerød
Denmark

Phone +45 4576 94 00
Fax +45 4576 94 01

emco@emco.dk

Emco Controls A/S receives the Gazelle award from the leading Danish business newspaper Borsen in recognition of being one of Denmark's fastest growing companies.

 

    

 

EMCO 4-electrode Conductivity Sensor series 821

 
for Alkali Concentration Measurement of White and Cooking Liquor
 
APPLICATIONS
The EMCO alkali sensor type 821 and the EMCO Analyzer type 580 calculate the concentration of white and cooking liquor in the pulp and paper industry by measuring the conductivity of the liquor.
In the digester in a pulp mill the wood chips are cooked with white liquor in order to remove the lignin and other unwanted substances. The lignin is the product which bonds the wood fibres together.
The white liquor is a chemical mixture of mainly sodium hydroxide (NaOH) and sodium sulphide (Na2S).
NaOH and Na2S are significantly much more conductive than the rest of the components in the white liquor. Therefore the conductivity can represent the effective Alkali (EA) and active Alkali (AA) concentration.
The sensors are designed to be installed directly into the feed circulations as it supplies the operator with a real time measurement and optimum conditions to fine tune the alkali and temperature in the process.
Sluice mounting or retractable under pressure types are available, see series 822.
Alternatively a complete bypass solution is available which includes additional items such as main pipe spool piece, bypass measuring pipe, valves, restriction orifice plate and cooler etc.
All items will be provided and manufactured by EMCO Controls.
 
 
CONSTRUCTION
The sensor element has a 4 electrode design for higher accuracy over the 2 electrode design.
The sensor element has an accurate temperature sensor with low response time for fast temperature compensation.
The sensor is to be mounted in a pipe size larger than 200 mm.
The cable to connect to the Analyzer is especially selected to ensure high accuracy
and long distance between sensor and analyzer. The cable is a part of the supply
of the sensor.
Our many years in the field of instrument design guarantees a roughed design,
but still allows the possibility to solve customers´ special requirements.
 
 
FEATURES
The sensor is extremely resistant to wear.
The disk type design ensures no risk of scaling (product build up).
The unique sensor design eliminates risk of catching air bubbles which would influence
measurement accuracy.
 
 
PRINCIPLE OF MEASUREMENT
The conductivity is equal to the conductance of the liquid times the cell constant.
The conductance is the reciprocal of the electrical resistance of the liquid measured.
The cell constant is equal to the distance between the electrodes divided by the
effective area of the electrodes.
 
Measuring range : 0- 2000 mS/cm
 
Process connection : Flange according to ANSI B 16.5, EN 1092-1 or DIN
 
Pressure ratings 300 lbs or PN 40
 
Sizes : 1½”, 2”, DN 40, DN 50.
 
Pressure max. : 30 bar
 
Temperature max. : 180°C
 
Material. sensor body : AISI 316, 22 Cr Duplex
 
Material. electrodes : AISI 316, 22 Cr Duplex
 
Material, electrode support : PTFE
 
Insertion length 286 mm
 
Temperature element : Pt1000 Class A IEC 751
 
Cell constant : Individually determined, marked on sensor
 
Accuracy better than 3 % (2 % per decade)
 
Protection IP 65
 
Electrical connection connector, 9 pin
 
Cable lengths : 3 m, 5 m, 10 m, 20 m, 30 m.
 
Suitable Analyzer : model 580


 
    

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