Co-ordination Action for Autonomous Desalination Units ... - ADU-RES

Fig 7 Product concentration
The medium-pressure pump is a Moineau (progressing cavity) pump. It sucks
seawater from a beach well or a tank in the case of the demonstration unit. A
submersible version of the same pump is available, at extra cost, and could readily
be substituted. The Clark pump raises its medium-pressure feed water to highpressure
by virtue of the energy it recovers from the brine. The flow ratio of the Clark
pump is fixed by design, which normally gives a 10% water recovery at the
membranes. However, the high-pressure plunger pump injects an additional feed,
which increases the water recovery to any desired value. The two pumps are driven
independently by two induction motors, rated at 1.5 kW and 3 kW respectively but
operated at well below these values. The speeds of the two pumps are carefully
controlled through the inverters (variable-frequency drives) in order to maximize the
overall system efficiency. The unit includes four 4-inch by 40-inch pressure vessels
in series, each housing a Koch high-flow seawater membrane type: TFC1820HF. No
post-treatment is included and, in the test rig, the product water is simply returned to
the feed tank.
The wind turbine is manufactured by Proven Energy, Scotland and is rated at 2.5kW.
It is gearless with and uses a variable-speed permanent-magnet generator. It has 3
blades, a rotor diameter of 3.5 m and a rated rotor speed of 300 rpm. It is mounted
on a 13m un-guyed tapered steel tower.
The AC from the generator is rectified and limited (voltage regulator) then fed directly
to the inverters. No batteries or other energy storage or backup are installed.
WP2 ADU-RES 19