Introduction
Control of sodium chloride (NaCl) concentration at a salt dissolver where solid salt is dissolved in water, is highly important because of the electrolysis efficiency. A conventional way of measuring the concentration of supersaturated NaCl solution had been performed by using non-contact type sensors (e.g., γ-ray density meter) since NaCl, impurities, and precipitates are in the solution. In this way, there were disadvantages such as troublesome maintenance and therefore, the radiation control is required for γ-ray density meter. Responding to these backgrounds, the FLXA202 2-wire inductive conductivity analyzer provides concentration reading and realizes to improve substantial maintainability, cost performance and measurement accuracy.
Caustic Soda Production Process
Expected Benefits
- Measures NaCl concentration in salt dissolvers
- Reduces operating costs
Process Overview
In an electrolysis plant, the solid salt is dissolved in water in a salt dissolver to make brine. This brine contains impurities, such as calcium, magnesium or sulfates, that decrease electrolysis efficiency. The brine is purified by removing these impurities before being fed to an electrolyzer, where the purified brine is electrolyzed to produce caustic soda and chlorine. The caustic soda solution produced at the cathode in the electrolyzer is concentrated in a multiple effect evaporator, as a result the concentration is increased from approximately 32% to 48%.
Solution Details
Measurement system
2-wire inductive conductivity system
| Sensor | ISC40G(J)-GG-T1-☐☐ |
|---|---|
| Flow-through holder | ISC40FF(J)-PJ |
| Transmitter | FLXA202-D-BｰD-☐-C5-NN-A-N-LA-☐-NN |
Inductive Conductivity Sensor & Transmitter Installation Diagram
Utilities
| FLXA202 2-wire inductive conductivity analyzer | |
|---|---|
| Power supply voltage: | 17 - 40 V DC (from distributor) |
| Power consumption: | 0.9 VA maximum |
| PH201G distributor | |
| Power supply: | |
| 100 V: | 20 to130 V DC/80 to 138 V AC, 47 to 63 Hz |
| 220 V: | 120 to 340 V DC/138 to 264 V AC, 47 to 63 Hz |
| Power consumption: | 24 V DC: approx. 200 mA |
| 100 V AC: approx. 7 VA | |
| 220 V AC: approx. 11 VA | |
Notes
Sampling should be done in the supernatant liquid in a salt dissolver. The supernatant liquid is collected in a settling tank and then the supernatant liquid of the tank is transported to a measurement tank where the sensor is installed.
Field Data
1. Process conditions (salt dissolver)
| Temperature: | Approx. 65°C |
|---|---|
| Pressure: | Atmospheric pressure |
| Sample: | Supersaturated brine |
| NaCl concentration control range: | 200 to 360 g/L |
| --> 18.1 to 30 wt%* | |
* Depends on user's actual data of specific gravity.
2. FLXA202 setting parameters
Relationship between conductivity and concentration is based
on the linear approximation of S = 16.3x that is obtained by actual measurement using SC72 Personal Conductivity Meter.
- NaCl temperature compensation table is used
- Reference temperature setting: 25°C
| Concentration (%) | Conductivity (mS/cm) |
|---|---|
| 18 | 293 |
| 24 | 391 |
| 30 | 489 |
Industrieën
-
Chemie
Chemische fabrieken zijn afhankelijk van continu- en batch-productieprocessen die elk verschillende eisen stellen aan een besturingssysteem. Een continu proces vereist een robuust en stabiel besturingssysteem dat niet faalt en de productielijn doet stilvallen. Bij een batchproces ligt de nadruk ligt op een besturingssysteem dat een grote flexibiliteit biedt bij het aanpassen van o.a. formules en procedures. Beide soorten systemen moeten worden beheerd naar aanleiding van de productiegeschiedenis rond de kwaliteit van het product, en in staat zijn om niet-routinematige werkzaamheden uit te voeren. Met een uitgebreide productportfolio, ervaren systeemingenieurs en wereldwijde verkoop- en servicenetwerk heeft Yokogawa een oplossing voor elk fabrieksproces.
-
Specialistisch en fijn chemisch
Yokogawa bedient al lange tijd klanten in de speciaal- en fijn chemie. Met een toonaangevende batchoplossing die de beste betrouwbaarheid en flexibiliteit in zijn klasse biedt, alsmede industrie-experts die de complexe eisen begrijpen die bij het ontwerpen van een batchoplossing komen kijken, kunt u er zeker van zijn dat u in samenwerking met Yokogawa een systeem krijgt waarmee u in de toekomst producten kunt produceren die voldoen aan de behoeften van uw klanten, terwijl de veiligheid en de naleving van de regelgeving gewaarborgd blijven.
Gerelateerde producten & oplossingen
-
2-Wire Transmitter/Analyzer FLXA202
The FLEXA™ series analyzers are used for continuous on-line measurements in industrial installations. With an option for single or dual sensor measurement, they are the most flexible two-wire analyzer available.
-
2-Wire Transmitter/Analyzer FLXA21
The FLEXA™ series analyzers are used for continuous on-line measurements in industrial installations. With an option for single or dual sensor measurement, they are the most flexible two-wire analyzer available.
-
Inductive (Torodial, Electrodeless) Conductivity Sensor ISC40
The model ISC40 sensors are designed for use with the FLEXA ISC analyzers. This combination exceeds all expectations for conductivity measurement in terms of reliability, accuracy, rangeability and price performance.
-
Conductivity Sensors
Conductivity sensors and electrodes are used to measure process conductivity, resistivity, WIFI, demineralizer water, RO water, percent concentration, boiler blowdown and TDS. Various installation options including retractable, flow thru, immersion, and direct insertion. Proper electrode/sensor selection is critical for optimal measurement results.
-
pH and ORP Analyzers
pH and ORP meters, analyzers and transmitters are used for continuous process monitoring of pH and ORP to ensure water/product quality, monitor effluent discharge, batch neutralization, pulp stock, scrubbers, cooling towers, chemical, water/wastewater treatment and many other applications.