The Service History and Performance of Titanium in Geothermal Systems

摘要

Titanium is well known throughout the chemical process industry for its excellent performance across a wide range of harsh environments. Over the last 50 years, titanium has been shown time and again to provide unsurpassed service in the chemical, petrochemical, metal refining/recovery, and many other general chloride containing applications. The same has been true for titanium in geothermal brine applications. The US Bureau of Mines first reported on the excellent corrosion performance of titanium more than 30 years ago. The Salton Sea KGRA has utilized titanium since the early 1990's to control the excessive corrosion being experienced in their production wells. Multiple alloys of titanium have been used, with, for the most part, complete success. Production wells that once had an anticipated life of ＜5 years using cement lined steel, with declining production during that life cycle, have now been operating for more than 15 years with titanium casing with no loss of production. It is expected that these titanium cased -wells will survive the life of the power plant. Titanium is also being considered and tested for use in more typical steam generating wells where HCl condensation has proven to be a corrosion issue and also for EGS applications where recirculated water becomes increasingly more corrosive over time. This paper will focus on the performance of titanium in hypersaline geothermal systems, titanium alloy grade selection criteria for production casing, and the application of titanium into more traditional steam producing geothermal systems.