DOI: 10.5176/2251-3353_GEOS15.44
Authors: Serguei N. Lvov* and Derek M. Hall and Isaac K. Gamwo
Abstract:Until now only a few computer codes have been developed for modeling the phase equilibria and speciation in high temperature aqueous solutions over a wide range of temperatures and pressures. Furthermore, those currently available rely on the Helgeson-Kirkham-Flowers (HKF) model (SUPCRT 92) to describe the standard thermodynamic properties of aqueous species, but fails to reliably predict them in high temperature (>350 °C) and low pressure (<500 bar) subcritical and supercritical aqueous fluids. Still, these conditions are important for a number of applications and the ultra high-enthalpy geothermal technology is one such example [1]. Previously, we found that incorporating molecular statistical thermodynamic expressions into the modeling of aqueous species can greatly improve the reliability of predicting hydrothermal equilibria in high temperature and low pressure systems, particularly those applicable in power plan water cycles and hydrothermal synthesis of materials [2, 3]. In this paper, we show how our model can be used for calculating quartz solubility at high temperatures and low pressures applicable to ultra high-enthalpy geothermal conditions. Calculated values were compared with available experimental data to confirm the validity of the modeling results towards predicting SiO2(aq) scaling in the ultra high-enthalpy geothermal systems.
Keywords: quartz solubility; supercritical fluids; ultra high enthalpy geothermal; silica scaling
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