Corrosion, Scaling and Material Selection in Geothermal Power Production

Abstract

Scaling and corrosion problems can occur in geothermal power production resulting in high costs associated with labor, materials, and production efficiency. The corrosion of the materials and scaling in geothermal systems is primarily dependent on the chemical composition of the geothermal fluid and on exploitation parameters such as temperature, pressure, and flow rate. The key corrosive species in geothermal environment such as dissolved H2S, CO2 gases and chloride ions are discussed in connection to different corrosion forms that can occur for metals in geothermal environments. Including uniform corrosion, pitting corrosion, stress corrosion cracking, crevice corrosion, hydrogen embrittlement, hydrogen induced corrosion, and sulfide stress corrosion. The occurrence of these corrosion forms is highly dependent on material used and the environmental conditions. Corrosion and scaling can be prevented or controlled with different methods. The best way to prevent corrosion is by correct material selection and good engineering design of equipment in geothermal wells and power plants. Other methods used to control corrosion are steam scrubbing and corrosion inhibitors. Corrosion or scaling in geothermal systems is generally not considered a limiting factor in the production of geothermal power. If they do occur, there are several methods that are discussed in this chapter that have proved successful in preventing or controlling these problems so that the production of geothermal power can be achieved in the most cost-effective and efficient way.