51313-02627-Silica Precipitation Kinetics Under High Temp. Geothermal Field Conditions w/Ultrasonic Techniques

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Product Number: 51313-02627-SG

ISBN: 02627 2013 CP

Author: Muhamad Andhika

Publication Date: 2013

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Located at tectonic plate boundaries Indonesia holds an enormous potential of geothermal resources. From estimated 27 GW potential only 4 % electricity is currently produced from high temperature geothermal fields. The silica concentration in these high temperature geothermal brines is usually very high (several hundred mg/L). This represents one of the main obstacles for binary geothermal plant operation due to potential silica precipitation (scaling) which frequently causes operational problems by clogging the pipelines reinjection wells and even the pores of the near boreholereservoir region (injection site). To prevent such uncontrolled silica precipitation this study aims in developing a method of fast silica removal from the brine.
A promising tool to monitor the kinetics of scale formation is the ultrasonic probe which allows online measurement of crystallization and crystal growth.

A 0.1 M silica solution was prepared by dissolving quartz powder in 0.5M NaOH solution and stirred at 50°C for 4 hours. This silica solution was placed into an autoclave which is equipped with an ultrasonic sensor that is attached together with a temperature sensor and a pressure gauge in an autoclave. Various experiments were conducted by modifying different parameter such as the pH value (12 7 4) metal content (addition of 1.1x10-4 M and 1.8 x 10-4 M of alumunium) ionic strength (1.7 x 10- M to 0.17 M) ) and temperature (30 °C to 180 °C) to investigate their effect on silica precipitation kinetics . The change of ultrasonic velocity was monitored over time online by a controller directly connected to the ultrasonic sensor.

Other analytical instrument measuring silica concentration such as photospectrometer were used as quality control and to confirm and quantify the result from the ultrasonic probe. By applying this method an exact characterization of the precipitation process in real time and at realistic in-situ conditions is possible.