| Title | Case study: Silica inhibitor trial in Central America plant |
|---|---|
| Authors | D. Parravicini, A. Guidetti, J. Kuy |
| Year | 2023 |
| Conference | New Zealand Geothermal Workshop |
| Keywords | silica, scale, geothermal, scale inhibitor, Central America |
| Abstract | This paper provides a description of a field trial performed in a geothermal plant in Central America affected by severe silica scaling. Silica is one of the most common and serious scale that geothermal operators have to face, and it typically deposits in the colder sections of the plant. Among all the different ways currently available for preventing silica deposition, the use of chemical inhibitors is considered one of the most promising and cost-effective approach. The presence of highly charged cations such as Al3+ and Fe3+ in the geothermal brine increase the severity of conditions as those cations boost silica polymerization and precipitation also affecting the efficacy of scale inhibitors and dispersants. For this reason, it is crucial to select and correctly apply the best product able to provide good protection even under harsh conditions. The trial started with two runs, as base lines, without the application of the scale inhibitor followed by a run where the scale inhibitor had been applied. All the trial runs had a duration of 30 days each and the plant operating condition were kept constant for the entire trial period. After each run, the system was cleaned up and scale coupons, placed in different area of the system, were extracted and analysed by measuring the scale weight and thickness together with a visual inspection of the pipelines. The performance comparison showed very good results obtained during the run with the scale inhibitor which registered a reduction of scaling by 70 to 80%. Also, the visual inspections showed much cleaner pipelines conditions after the run with the product. This work confirms how the use of a proper scale inhibitor, even at low dosage, could mitigate the negative effects of silica deposition, increasing the efficiency of the plant and the power recovery and eliminating the need of costly shutdowns for mechanical cleaning. |