P29 超音波による地熱水中のシリカ重合の促進効果(ポスターセッション)

概要

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A serious problem encountered in geothermal power plant is deposition of silica scales at undesired locations of solid surfaces in a heat exchanger and a conveyance system. Prior reduction of silica monomer concentration from silica rich process-water is effective to prevent scaling at undesirable locations. In this study, ultrasound is irradiated to silicic acid solution, and concentration changes of silica monomer and total silica were measured. Compared with stirring, the reduction rate of silica monomer concentration increased for ultrasonic irradiation at 500kHz. The reaction rate constants were maximum at about the solution pH of 8. The total silica concentration for irradiation at 500kHz decreased owing to formation of large silica particles. The formation ratio of large silica particles became larger below the solution pH of 7. It is considered OH radicals due to pyrolysis of water accelerate polymerization of silica monomer. In addition, the zeta potential of silica particles influences formation of large silica particles.
2013-10-25