The behavior of silica in geothermal brine from Dieng geothermal power plant, Indonesia

• We investigate the silica concentration in the canal and polymerization under constant temperature.
• We measure temperature, pH and chemical concentration of Dieng geothermal brine.
• Dieng fluid reservoir shows a very high silica and salt concentration.
• Acidification suppresses the deposition of silica in the canal.
• Polymerization experiment indicated that the concentrations of total and monomeric silica decreased quickly initially.

Silica scaling in the Dieng geothermal power plant was investigated experimentally. We conducted two kinds of polymerization experiments to examine the behavior of silica in brine along the canals at production wellpads. Acid-treated and untreated brines were sampled along the canal to understand the effects of acidification on silica polymerization and deposition. Chemical analysis of the Dieng brine indicated high silica and salt concentrations. Silica concentrations of acid-treated brine showed that acidification successfully suppresses the deposition of silica along the canal, preventing it from fulfilling its purpose of depositing as much silica as possible. In contrast, significant silica polymerization occurred along the canal when the brine was not acidified. Batch experiments for silica polymerization at constant temperature indicated that both concentrations of total and monomeric silica decrease quickly in early times followed by gradual decrease with time.