| Title | Heavy Metal Scaling and Corrosion in a Geothermal Heat Exchanger |
|---|---|
| Authors | Rosalind JULIAN, Keith LICHTI, Ed MROCZEK, Bruce MOUNTAIN |
| Year | 2015 |
| Conference | World Geothermal Congress |
| Keywords | heat exchanger, corrosion, arsenic, galvanic corrosion, acid, two-phase |
| Abstract | Recent energy extraction from two-phase geothermal fluids using an angled heat exchanger arrangement resulted in carbon steel tube corrosion to perforation in the central part of the heat exchanger. Arsenic sulfide scales and iron based corrosion products were observed with occasional formation of elemental arsenic. The main damage occurred in a small part of the heat exchanger where local conditions were asserted to have resulted in a decrease in pH, enhanced elemental arsenic formation and localised corrosion. The damage mechanism appeared to be related to the local pH change however there was strong evidence for some influence of galvanic corrosion of the carbon steel having overlaying elemental arsenic. A design change to avoid formation of acidic fluids has been implemented with success. The scaling and reduction of arsenic/corrosion of iron processes highlighted by this two-phase geothermal heat exchanger failure will be explored in this paper. |