| Title | Increasing the Temperature of Geothermal Fluids as a Mitigation Measure against the Formation of Unwanted Solids at the Pailas II Geothermal Field Plant |
|---|---|
| Authors | Federico Nietzen |
| Year | 2026 |
| Conference | World Geothermal Congress |
| Keywords | generation decline, unwanted solids, temperature increase of geothermal fluids, silica compounds in steam, Pailas II Generating Unit. |
| Abstract | The Pailas II Generating Unit at the Pailas Geothermal Field (Costa Rica) began commercial production in August 2020, with a gross output of 55 MW (condensing steam turbine technology). However, just over a year after commissioning, a significant decline in generation was observed; subsequent analysis determined that the main cause was the formation of unwanted byproducts in the plant's internal systems, including the turbine. These byproducts not only affect plant efficiency but also the useful life of critical and expensive components. From late May 2022 to early August 2022, the generation decline at the Pailas II Unit was halted, maintaining an average output of 49.5 MW, by increasing the system pressure to 6 bar without changing the turbine's operating pressure. This action is performed to increase the system temperature (by increasing the pressure) and thus the solubility of silica compounds in the liquid phase, mitigating the formation of silica salts in the plant elements. Furthermore, with the increase in pressure, it was expected to improve the capture of other solids entrained by the steam in the separation stations by increasing the resistance (suspended solids would be expected to migrate to the bottom of the separator, thereby minimizing the passage of solids from the two-phase fluid to the steam pipe). The defined monitoring variable is the decline in the plant's generation rate, observed in the generation curve of Unit Pailas II; the decline tends to stop with these actions. |