<p>ALSTOM (Switzerland) Ltd Patent Information Date of first application: 29.01.2003, Country: DE, Ser. No.: 103 03 341.6 Keyword: Mantelkühlung von Gasturbinen-Luftkühlern Inventor: Dr. Mustafa Youssef</p><p>An air cooler (10) for power stations (40) comprises a pressure vessel (39), said pressure vessel (39) containing a coaxial arrangement (24, 25, 26) of a cylindrical central pipe (24), a helical pipe assembly (25) surrounding said central pipe (24), and a cylindrical casing (26) surrounding said pipe assembly (25). The central pipe (24) opens into a first space (33), which is situated at a first end of said coaxial arrangement (24, 25, 26) just behind said pipe assembly (25), and which is en- closed by said casing (26). At a second end of said coaxial arrangement (24, 25, 26) the central pipe (24) can be fed with air from outside by means of an air inlet socket (23) running through a second space (34) adjoining said pipe assembly (25). Furthermore, connecting means (31, 32) are provided for feeding said pipe assembly (25) with water from said second end of said coaxial arrangement (24, 25, 26) and for getting steam from said pipe assembly (25) at said first end of said coaxial arrangement (24, 25, 26). Finally, the second space (34) is connected to the outside by means of an air outlet socket (29).</p><p>For such an air cooler (10) a sufficient cooling of the pressure vessel (39) is achieved by surrounding said pipe assembly (25) and said first space (33) with an inner casing (26) being separate from said pressure vessel (39), whereby said inner casing (26) is coaxially surrounded by a cylindrical outer casing (28) of said pressure vessel, thereby creating a ring slot (27) between said inner casing (26) and said outer casing (28), and whereby a third space (35) is provided outside of said first space (33) and inside of said pressure vessel (39), said third space (35) being connected to said second space (34) by means of said ring slot (27), and being connected to said air outlet socket (29) through separate connecting means (30, 36, 38), such that the pressure (p3) in said third space is smaller than the pressure (p2) in said second space.</p>