Low temperature multi effect distillation is a simple, reliable and efficient process utilizing low cost / low grade heat or waste steam. Vacuum enables operation at unparalleled low distillation temperatures (below 70 °C) minimizing scale and corrosion, and hence maintenance, to an absolute minimum. A large number of effects consequently results in very high economy ratios (product to steam) and the use of aluminum tubes improving the heat transfer results in lower investment cost compared to conventional high temperature processes.
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Evaporation and condensation are achieved by direct transmission of latent heat, avoiding sensible heat pickup, which would decrease the effective temperature differential. Using the falling film concept, static head is eliminated from the flashing process and high evaporation heat transfer coefficients result.
These factors, together with generously designed heat transfer surfaces, provide low thermal driving forces and reduce energy requirements. Furthermore, as the brine circulation rate is an order of magnitude lower than that required in forced circulation systems, there are considerable savings in pumping power.
The design of AquaSwiss evaporators is extremely safe as there is no pressurized brine flow, and brine pressure is always lower than steam or product pressure. Thus product contamination is consequently impossible even if there should be tube perforation. Also, due to the laminar film type flow, there is no erosion of the tubes and pitting corrosion rates are minimized.
All standard items of equipment in the plant, such as pumps, motors and controls are of top quality and reliable design, purchased only from reputable international manufacturers.
AquaSwiss MED plants are typically installed in power plants, refineries or other industries, and demonstrate very high availability and reliable operation with ease of maintenance.
AquaSwiss MEDs are:
- suitable to treat brackish and seawater
- able to produce boiler feed water with less than 10 ppm TDS guaranteed
- superior in availability and reliability
- flexible with load-following capabilities
- highly efficient with optional utilization of low cost waste heat energy sources
References:
- White paper MED advantages over MSF (.pdf)
- MED V/S RO Comparison (.pdf)