Singapore's seawater desalination solution
May 2010
Analytical Instrumentation & Environmental Monitoring
Singapore began tackling its drinking water supply problem a few years ago. The first large seawater desalination system ‘TUAS Desalination’ was designed and built by Hyflux. The system operates according to the reverse osmosis principle and produces more than 136 000 cubic metres of drinking water per day – enough to fill about 55 Olympic size swimming pools.
Technology and process
Seawater desalination runs in several process steps. The first of these is the drawing of the seawater and feeding into the system. This is followed by a multistage filtration, flotation and ventilation to remove suspended matter and undesirable substances dissolved in the water. The filtered water is conditioned with ferric chloride, sulphuric acid, hydrochloric acid, caustic soda and other additives for reverse osmosis and set to a specific pH. Without these important water treatment steps, the downstream osmosis diaphragms would become useless very quickly.
After conditioning of the water, it is fed to the osmosis diaphragm modules by high-pressure pumps. The systems have a modular structure so that the diaphragms can be backwashed at regular intervals. In a system with 10 modules, for example, one of them is always in backwash mode whilst the others produce drinking water. In the last part of the system, after the reverse osmosis, which supplies almost distilled water, the water is brought back up to drinking water quality mineral content. This is the final process step before the water is fed into the distribution pipes and sent on its way to the consumers.
The GEMÜ solution
GEMÜ supplied more than 760 valves in nominal sizes from DN 15 - 1400 for this project. To offer the customers a package solution, valves were also purchased from partner companies. The customer could therefore be offered everything from a single source.
Butterfly valves with the different disc materials in 1.4408, bronze or ECTFE coated are mainly used in the seawater inlet, in the filtration/flotation and in the supply (tanks and pump stations). The nominal sizes are between DN 65 – 1400 and the operating pressure is 2,5–18 bar depending on the process area. Positioning is via pneumatic and electric solutions as well as manual operation using hand levers and gears.
In water pre- and post-treatment, highly chemically resistant diaphragm valves made of PVC or PVDF are used for the chemical dosing processes. The nominal sizes are DN 15 - 40, operating at pressures from 3-5 bar. Float flowmeters of nominal sizes DN 20 – 40 are also installed. Chemical dosing is fully automatic so the valves are usually controlled pneumatically.
The high pressure and non-return valves on the pump stations in front of the osmosis modules are made of special materials such as Super Duplex A890. They are controlled pneumatically and equipped with intelligent positioners. The differential pressure in the start-up phase of a pump is up to 60 bar. The operating pressure is usually between 5–84 bars the valves are designed in DN 300 throughout.
For more information contact Keith Hedges, GEMÜ Africa, +27 (0)11 462 7795, [email protected], www.gemue.de
Further reading:
Analysers for use in high ambient temperature environments
Analytical Instrumentation & Environmental Monitoring
The 993X series of analysers from Ametek Process Industries are now IECEx Zone 2 certified for use in locations with up to 60°C ambient temperature. Built with IP66-rated enclosures and using an integrated cooling system, they can be installed outdoors or in minimally temperature-controlled enclosures, reducing complexity while lowering capital and operating costs.
Read more...
The art of precision measurement
Analytical Instrumentation & Environmental Monitoring
To achieve precise, reliable measurement results when scanning component parts, use is frequently made of reference points. In optical measuring processes, these permit the referencing of three-dimensional objects during the digitisation.
Read more...
Vibration test system supports international space industry
TANDM Technologies
Analytical Instrumentation & Environmental Monitoring
Dragonfly Aerospace has launched EOS SAT-1, one of seven satellites in the world’s first agricultural-focused constellation. With optimisation of resources being a key component for Dragonfly, it called on TANDM to assist in creating and heavily expanding its environmental testing capabilities by providing a vibration test system that allowed it to perform in-house vibration and shock testing.
Read more...
Sensor technology for brewing
Endress+Hauser South Africa
Analytical Instrumentation & Environmental Monitoring
Brewing is a delicate balance, blending tradition with innovation. Now, modern sensor technology is stepping in to perfect the art of fermentation.
Read more...
Loesche gets dirty
Loesche South Africa
Analytical Instrumentation & Environmental Monitoring
The world’s attention is on environmental sustainability, and the pressure on countries and companies to demonstrate their commitment to preserving the environment and preventing climate change is at an all-time high. As we confront a multitude of environmental and social challenges, managing waste and maximising landfill diversion can play a key role.
Read more...
Water systems with energy savings and sustainability
Labotec
Analytical Instrumentation & Environmental Monitoring
ELGA Veolia has relaunched its award-winning PURELAB flex range, with features to reduce the system’s environmental footprint and incorporate some of the latest innovations in water purification technologies. The ecological improvements integrated into the flex range have been made to reduce water and power consumption.
Read more...
Keeping an eye on invisible radiation
Omniflex Remote Monitoring Specialists
Analytical Instrumentation & Environmental Monitoring
At its peak in 1994, the energy generation capacity of the UK’s nuclear power stations was 12,7 GW across 16 plants. In 2024, the capacity has fallen to around 5 GW, and the number of stations is down to nine. However, this is far from the end of the story as spent nuclear fuel remains radioactive for centuries, and requires rigorous safety processes to safeguard against leaks.
Read more...
Technology for water sustainability
Endress+Hauser South Africa
Analytical Instrumentation & Environmental Monitoring
The sustainability of surface water is critical for South Africa’s economic development, social well-being and environmental health. Endress+Hauser has a full range of liquid analysis sensors and transmitters to measure important parameters and has an excellent global track record in water and wastewater process plants and various surface and industrial water monitoring sites.
Read more...
Reducing water consumption in the cement industry
Loesche South Africa
Analytical Instrumentation & Environmental Monitoring
Water is a finite and irreplaceable resource, fundamental to life on earth. LOESCHE’s vision is to enable its customers to produce high-quality cement, without any water consumption.
Read more...
Ensuring occupational health and safety in mining
Analytical Instrumentation & Environmental Monitoring
Probe Integrated Mining Technologies (Probe IMT) has partnered with M3SH Technology to offer state-of-the-art environmental monitoring solutions that address these dual requirements.
Read more...
printer friendly version