| Abstract |
Corrosion can often happen in geothermal plants due to high temperature and the presence of significant number of chlorides in the liquid phase and CO2 and H2S in the gas phase. In some cases, the use of acid to reduce pH to delay amorphous silica formation, can increase the risk of corrosion issues that could eventually lead to loss of power or heat generation or, in severe cases, shutdowns to replace the corroded part of the plant. The use of corrosion resistant alloys is a currently used approach, but it increases CAPEX associated with a new geothermal plant. For this reason, effective treatment based on a corrosion inhibitor is becoming attractive. Due to the high temperature, most of the film forming corrosion inhibitor cannot be used as they rapidly degrade. In this work, to identify the most suitable solution, high temperature weight loss coupon test has been performed on several different technologies and the most promising was then evaluated under different conditions. Another important aspect is the interaction between scale and corrosion inhibitors that in some cases could lead to unexpected loss of performance in the field. A proper selection of these chemicals is crucial for obtaining the desired protection in the plant. This aspect was also evaluated in this paper, with both scaling and corrosion tests carried out in the presence of corrosion and scale inhibitors. After this extensive lab work, a field trial to confirm corrosion properties under real field conditions was scheduled. Details and results are discussed and analyzed in the paper. |