Geothermal power generation system and silica scale deposition control method

A geothermal power generation system comprising:

• a steam separator configured to separate a geothermal fluid which is obtained from a production well, into steam and hot water;
• a turbine that is configured to be rotated by the steam separated by the steam separator;
• a reinjection well configured such that the geothermal fluid that has passed through the steam separator and/or the turbine is returned;
• a pH measurement system configured to extract a part of the hot water separated by the steam separator and measure a pH of the hot water, and a first thermometer configured to measure a temperature of the hot water;
• an injection device configured to inject an alkaline chemical into the geothermal fluid;
• a second thermometer configured to measure a temperature of the geothermal fluid at a pH estimation point selected from a group of sites in the system including an injection portion of the injection device for the alkaline chemical, an outlet of the steam separator, and an inlet of the reinjection well;
• and
• a control device configured to control injection of the alkaline chemical by the injection device, on basis of measurement results of the pH measurement system, the first thermometer and the second thermometer,
• wherein the pH measurement system includes a spiral pipe and a pH meter, and is connected to a condensate pump downstream of the turbine via an on-off valve.