MULTI-STAGE-FLASH DESALINATION PLANT WITH SOLAR ENERGY AS THE MAIN ENERGY SOURCE AT LAMPESDUSA ISLAND

Ziel

For isolated islands in the Mediterranian climate the water supply is very often crucial for the inhabitants and their economic development. The project's aim was to use solar energy for desalination of sea water. Currently the desalination is based on oil as the energy source. The working conditions of concentrating collectors and a multi-stage-flash (MSF) desalination unit should be demonstrated in this project. With the experience gained other desalination projects should follow.
Solar plant with a total surface of 408 m2.
The installation did not meet the expected output. The solar system consisting of concentrating collectors is not suitable for a site near the sea. The use of the uncovered BELMAR collectors was therefore interrupted due to continuous corrosion on the polished stainless steel mirrors. Apart from the problems with salt water the dust deposit lowered the performance to 40% of a clean collector. It was found to be not advisible to use two different collector types on one installation. The overall efficiency of the solar collectors was much lower than the individually tested collectors.
The MSF desalinator worked poorly under partial load. The sea-water used for the desalination had to be cut down to approx. 1 000 l/h (50%). The production of distilled water was low 80-120 l/h instead of 300 l/h.
The total energy consumption per kg of distilled water was
thermal 320.2 Kcal/Kg = 0.372 KWh/Kg
electrical 66.1 Kcal/Kg = 0.077 KWh/Kg
---------------------------------------
386.3 Kcal/Kg 0.449 KWh/Kg
for an evaporation under atmospheric pressure approx. 0.626 KWh/Kg (2 250 KJ/Kg).
Lampedusa is an Italian island situated between Sicily and the Lybian coast. The solar conditions are very favourable for the proposed use. The island itself has no substantial water ressources, of its own.
Characteristics of the solar field:
Collector type: concentrating linear parabolic
Belmar Contraves
(Italy) (Switzerland)
Number of collectors: 96 16
Net collecting area: 288 m2 120 m2
Orientation with respect to the horizon: 35 deg 35 deg
Tracking system: E-W E-W
Concentration ratio: 13:1 6:1
Collectors steady yield: 55% 45%
Reflectors:
Polished inox steel 19/10 AISI 304
HA parabolic cylinders X
anodized alluminium parabolic cylinders,
glass covered X
copper tube absorber with black selective
paint, insulated by a pyrex tube, coaxial;
the system employes distilled water as
heat-carrying fluid X X
The CONTRAVES collectors are installed inside a greenhouse, the BELMAR collectors in the open air.
The solar section also includes:- electronic focusing with solar tracking east-west, maximum error 0.05 deg
- automatic return position: started automatically at start of tracking.
- Auxiliary heating system, consisting of a steam/water exchanger (E-102), a storage tank (D-102) a steam generator (30 000 - Kcal/h).
This system is part of the desalination unit;
- titanium plate-type heat exchanger (E-101, 30 000 Kcal/h) intented for final heating of the sea-water flowing in the desalination unit.
The "Multiflash" (MSF) desalination unit consists of a MSF type module having a production capacity of 300 l/h of distilled water. The temperatureduring operation ranges from 95 deg to 115 deg C. Its main features are:
- sea-water capacity: 2 m3/h
- distilled water capacity: 300 l/h
- need in thermal energy: 100 Kcal/l of distilled water
- Ca content of sea water: 520 ppm
- purity of the distilled water: 100 ppm of salts
The plant is situated directly on the coast approximately 15 m above sea level.

Programm/Programme

ENG-ENALT 1C - Programme (EEC) of financial support for projects to exploit alternative energy sources, 1979-1984

Thema/Themen

3.1 - THERMAL

Aufforderung zur Vorschlagseinreichung

Data not available

Finanzierungsplan

DEM - Demonstration contracts

Koordinator

Agip Nucleare SpA

EU-Beitrag

Keine Daten

Adresse

Viale Brenta 27-29
20139 Milano
Italien

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