Scaling Prevention Experiments in the Hellisheiði Power Plant, Iceland

Abstract

The Hellisheiði Power plant produces electricity by separating geothermal fluid at 9 bar-a where steam is conducted to turbine units and the resulting separated water is flashed to 2 bar-a for additional production of steam. The 120 °C separated water is then conducted to heat exchangers for production of 88°C water for district heating. During these processes, silica super-saturation of these waters is elevated and a correct fluid handling is vital for a successful disposal of the geothermal brine.
Silica deposition experiments with varying brine/condensate ratios, acidification and brine temperature were carried out to propose a methodology to prevent scaling from the brine in pipes and injection wells. These results were then combined with selected operational and environmental parameters in order to optimize the re-injection system of the power plant.