Method for imitating magnesium silicate scale formed at the geothermal power plant in Obama Hot Spring, Japan

Abstract

To shorten the development period of suitable anti-scaling technology for individual geothermal plants, it is necessary to improve the precision in evaluating the scaling technology through laboratory testing. Therefore, in this study we investigated a method to imitate the structure of magnesium silicate scale that has precipitated in Obama Hot Spring in Nagasaki Prefecture, Japan. Magnesium silicate hydrates were synthesized in an artificial solution at 100°C under different environments (i.e., carbon dioxide, nitrogen, and atmosphere). The synthesized solutions with magnesium silicate hydrates were flowed to the inner surface of a carbon steel pipe, and the scaling propensity of magnesium silicate was evaluated. Among the samples, the ones synthesized under the carbon dioxide environment have a similar structure with the field magnesium silicate scale and exhibited high scaling propensity. We believe that the findings are useful to eliminate the gap between the characteristics of field scaling and laboratory testing.