51314-4152-Corrosion Testing of Heat Exchanger Tubes in Steam from the IDDP-1 Exploratory Geothermal Well in Krafla Iceland

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Product Number: 51314-4152-SG

ISBN: 4152 2014 CP

Author: Ingolfur Thorbjornsson

Publication Date: 2014

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The IDDP-1 well in the Krafla geothermal field in Iceland is the first well in the Icelandic deep drilling project (IDDP). The superheated steam from the well is extremely hot showing temperatures up to 450°C at a pressure over 120 bar at the wellhead. The IDDP-1 steam contains acid gas (HCl and HF) and is highly corrosive when it condenses. A test unit with eight different types of heat exchanger tubes was set up in order to investigate the possibility of using the IDDP-1 steam directly for heat exchangers without prior removal of silica sulfur and acid gases. The tube materials were three types of stainless steel 254SMO Sanicro 28 and SAF 2707HD titanium grades 2 and 7 and nickel alloys 825 and 625. In addition one low carbon steel tube was added as a reference. The inlet temperature and pressure were 330-350°C and 52-62 bar. The steam condensed in the tubes with an outlet temperature of about 270°C. Severe problems were encountered in the use of steam traps at the outlet end of the tubes due to clogging by silica and they had to be replaced with orifice plates. This paper reports the results from the testing and inspection of the pipes including visual inspection and microstructural and chemical composition analysis with SEM and EDS equipment.