IntroductionIf water is present after the dry chlorine tower in brine electrolysis plants, the downstream compressor is corroded or the product quality is deteriorated. The moisture level is measured before and after the compressor to prevent the corrosion of the compressor and the deterioration of quality. Conventional trace moisture analyzers using a phosphorus pentoxide (P2O5) sensor measure process gas with the contacting sensor so there are problems such as the deterioration of the sensor, slow response time, high maintenance, and high running costs. The TDLS200

Laser Analyzer is the solution to these problems.

Expected Benefits– Reliable measurement with less deterioration by non-contact

measurement

– Ability to measure even corrosive gasses with less deterioration reduces the maintenance and running costs

– Fast response to and stable measurement of changes in H2O concentration

Industry: ChemicalProduct: TDLS

Electrolysis Plant Trace H2O (Moisture) Measurement by the TDLS200

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Process OverviewChlorine gas generated in the brine electrolysis plant is dehumidified in the wet chlorine tower and sent to the drying tower where the chlorine gas is dried using sulfuric acid solution. The dried chloride gas is sent to the dry chloride tower where the gas is dehumidified, and finally, the dry chloride gas is compressed by the compressor and liquefied, and then shipped as a product.

APPLICATION NOTE

Electrolysis Plant Exterior View of TDLS200 Trace Moisture Analyzer

Raw material (salt)

DissolverRefining tank

(Secondary refining)Refined brine storage tank

pHadjustment

Electrolysis tank

(Low concentration brine)

Desalination tank

(Brine circulation)

Cooling tower

Wet chloride tower

Drying towerDry chloride tower

98% sulfate

Compressor

Liquefaction tank

Chloride gas

Cooling tower

Hydrogen gas tank

Hydrogen gas

Refined water

Electrolytereceivingtank

Concentrate drum

Concentrated caustic soda

Liquid caustic soda

: Measurement point

ppmH2O

ppmH2O

Solution Details Unlike analyzers using a phosphorus pentoxide (P2O5) sensor, the TDLS responds fast to changes in the trace moisture of the

sample.

Field Data

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TDLS Analyzer

• TDLS200

Available on a special order basis.

APPLICATION NOTE

Responsiveness Comparison between the TDLS200 and Moisture Analyzer Using P2O5 Sensor

Configuration Example of TDLS200 Laser Analyzer Trace Moisture Measurement A sampling system is used to introduce a process gas into the flow cell to measure it.

Notes

• Power supply: 100 - 240 V AC, 50/60 Hz

• Purge gas: Instrumentation air and N2 Inside the sampling board and the light emitter and light receiver boxes

Purge: Instrumentation air 10 L/min

Laser light transmission region purge: N2 flow rate 5 L/min

FeaturesD

ryer

1057514 429

(2000)

Exhaust

Exhaust

Exhaust

Sample gas (outlet)

Sample gas (inlet)

Lightemitter

1016 (path length)

Flow cell (with heat trace)

Sample cell heat trace controller

Lightreceiver

Unit: mm

Instrumentationair inlet

N2 gas inlet

Span gas inlet

-tek & Cylinder

0.0

1.0

2.0

3.0

4.0

5.0

6.0

HO

ppm

TDLS200

2

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4.91 ppm cylinder H2O sample exposed for one hour

Phosphoruspentoxide

TDLSindicated value

Idealvalue

Fast response with a rise within 30 seconds and recovery within 2 minutes

TDLS200:

Phosphorus pentoxide sensor:The peak has not reached even after more than one hour, and it takes more than 20 hours to return to the original value

Phosphorus pentoxide sensor

• A proprietary sampling method enables a high-sensitivity measurement (in the minimum range of 0-30 ppm)

• In-situ calibration is possible without removing the system

• The sampling system minimizes the effect of moisture in the purge gas