In the global supply of drinking and industrial water, seawater desalination plays a crucial role. As a result, more and larger plants are being built – especially in arid regions. WIKA is available to the industry in this market segment as an experienced solution partner. Customers benefit from a broad product portfolio of measuring instruments and accessories, supplemented by in-depth expertise in special materials for critical applications.
More than 22,000 seawater desalination plants are in operation around the world. The largest, with capacities of one million or more cubic metres of water per day, are concentrated in the Near and Middle East and the USA. Plants in Europe are mainly located in Spain and other countries bordering the Mediterranean.
Reverse osmosis is the most common process for seawater desalination
The most commonly used method for desalinating seawater to date is reverse osmosis. Plants that use this process first remove all unwanted components, which can range from algae to garbage, from the seawater. After this process, the water enters the actual reverse osmosis. Here, it is passed, usually at a pressure of 60 to 80 bar, through semipermeable membranes that retain the salt. The fresh water obtained in this way is then treated and stored as drinking water, with the addition of fluorine and chlorine, among others, in accordance with the applicable regulations.
During reverse osmosis, the salinity in the water remaining upstream of the membranes increases continuously. This brine is subject to a recirculation process that finally discharges it into the sea in a biologically safe manner.
“One-stop shop” – from measuring instruments to instrumentation valves
WIKA supplied these products, among others, for the instrumentation of the seawater desalination plant mentioned in this post (from left to right): model TR10 resistance thermometer, model 990.12 diaphragm seal, model 263.30 pressure gauge, model DW differential pressure switch and model BNA bypass level indicator.
All processes require reliable and accurate measurement technology to control them. For example, WIKA supplied instrumentation solutions for pressure, level and temperature for a large-scale plant operating with reverse osmosis. This possibility of a “one-stop shop” was a decisive argument for the customer. During the process phases, pumps, filters, water and chemical tanks as well as structures for pressure compensation or for damping pressure surges need to be provided.
WIKA supplied a complete package with tailored systems for the various measuring tasks. It included:
- Pressure gauges, diaphragm seals, pressure switches and differential pressure switches
- Level indicators and level switches
- Resistance thermometers, temperature transmitters and thermowells
- Instrumentation valves and flushing rings for the safe process adaptation of the instruments at critical measuring locations and also for maintenance or cleaning work without prior dismounting of the respective instruments.
PTFE coating for applications with very high salt concentrations
Another factor in WIKA’s favour was its ability to design wetted parts for use with aggressive media using suitable special materials. At measuring locations with a very high salt concentration, for example, the connections and diaphragms of the diaphragm seal systems, as well as the wetted components of the bypass level indicators, were given a PTFE coating. Monel was chosen for thermometer thermowells in applications involving chemicals.
Seawater desalination is carried out globally. WIKA has production sites in all key markets and a close-knit sales network. Plant operators therefore benefit not only from the group’s comprehensive expertise in measurement technology, but also from short delivery times worldwide.
Note
On the WIKA website, you can get an overview of our entire product portfolio. We also present further measurement solutions for the water and wastewater industry there. If you have any further questions, please do not hesitate to contact us at any time.
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