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Products and solutions, 2001-04-23, 02:00 AM

NIROSTA® combats drinking water scarcity

KTN receives biggest order yet for sea water desalination

Krupp Thyssen Nirosta GmbH (KTN) is to supply around 5,400 tons of stainless steel for the construction of the Al-Taweelah A1 seawater desalination plant in Abu Dhabi. The contract, worth more than 14 million euros, is the biggest order yet received for seawater desalination plants by the Krefeld-based company. The customer is the French company Sidem Société International de Dessalement, which is building the plant for the Abu Dhabi ministry for electricity and water.

With a capacity of around 240,000 cubic meters per day Al-Taweelah A1 is the biggest seawater desalination plant currently under construction. It will work on the Multiple Effect Destillation (MED) principle, a technology in which Sidem is world market leader. In MED plants drinking water is produced by evaporation and condensation of seawater. The plants consist essentially of a series of stainless steel boilers or evaporators which house bundles of heat exchanger tubes.

At the beginning of the process seawater is heated to boiling point and the vapor is passed through the heat exchange tubes of the first evaporator. Cold seawater is sprayed on to the hot tubes from above, causing the vapor in the tubes to condense into fresh water which is collected at the end of the tube bundle. At the same time some of the cold seawater applied from above evaporates. This vapor is passed through the tubes of the next evaporator, where the same process is repeated. Al Taweelah A1 consists of a total of 14 evaporator units arranged in series.

Most of the plant will be made of NIROSTA® 4404. It was chosen because of KTN`s ability to supply the material hot and cold rolled in the full size range specified. KTN is supplying the austenitic stainless steel in thicknesses from 2 to 70 millimeters, widths from 1,000 to 3,000 millimeters and lengths from 4,000 to 11,000 millimeters. The steel will be shipped from Krefeld to the Republic of Korea, where a subsidiary of the Hyundai group will make the equipment according to Sidem specifications.

Seawater desalination plants have developed into an important growth market for KTN. In view of rising living standards, a growing world population and increasing use of fresh water in agriculture and industry, drinking water is gradually becoming a scarce commodity. Some forecasts predict that a third of the world`s population could suffer water shortages around 25 years from now. One way of meeting this threat is to build seawater desalination facilities. Because the equipment is exposed to high corrosion loading from the saltwater, large quantities of stainless steel are required.

KTN has been active in this market for some time and for example also supplied around 2,500 tons of stainless steel for the Al Hid plant in Bahrain. An innovative product developed by KTN and Fischer Edelstahlrohre GmbH specifically for seawater desalination is in use in a brackish water desalination plant on the Rhine estuary near Rotterdam: the tube heat exchangers in this plant consist of a total of 1.4 million meters of thin-walled laser-welded tubes made of NIROSTA® 4565 S from KTN. The tubes, with a wall thickness of only 0.3 millimeters, are the first of their kind on the market and a cost-effective alternative to the copper-nickel or titanium alloy tubes commonly used for the heat exchangers. The plant, operated by NV Afvalverwerking Rijnmond, has been in operation since November 1999 and the new tube heat exchangers have been performing without any problems whatsoever.

<b>For further reference:</b> ThyssenKrupp AG, Trade Press, Bernd Overmaat
Tel: +49-211-824-36012, Fax: +49-211-824-36035
e-mail: overmaat@tk.thyssenkrupp.com

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