Salt solubility and deposition in high temperature and pressure aqueous solutions

Published

January 1, 2004

Author(s)

M S. Hodes, K A. Smith, Wilbur S. Hurst, Walter J. Bowers Jr., P Griffith, K Sako

Abstract

Solubility and deposition experiments were performed with aqueous sodium sulfate and potassium sulfate solutions at elevated temperatures and pressures typical of the Supercritical Water Oxidation (SCWO) process. For all experiments the test cell was the six-port chamber described by Hurst et al. that was fabricated by modifying a 1.91 cm (3/4 in) diameter Sawelok cross. One port was used to mount an internally heated cylinder (hot finger) into the center of the chamber and the remaining ports provided fluid cross flow, windows and instrumentation access. Experimental determinations of solubilities were acquired by maintaining the surface temperature of the hot finger approximately 15 degrees C above the bulk temperature of the solution flowing by it while gradually increasing the bulk solution temperature. The hot finger surface temperature at which precipitation first occurs is the solubility temperature. The solubility temperatures of sodium sulfate and potassium sulfate in water at a pressure of 25 MPa were measured for salt concentrations of up to 10% mass fraction. In the deposition rate experiments, the aqueous salt solution flowing past the hot finger was preheated to a temperature close to that at which precipitation begins and the salt layer-solution interface formed on the hot finger was maintained slightly above the precipitation temperature. Experimental deposition rate data for sodium sulfate- and potassium sulfate-containing SCW streams were obtained by measuring the mass of the salt deposited after removing the hot finger from the cell following each run. The deposition rate data were obtained at a pressure of 25 MPa as a function of the concentration of salt in the solution entering the test cell (2% to 8% mass fraction) and time (6 min to 12 min). Solubility data is compared to those from other studies and a simple deposition rate model is developed and compared against the deposition rate data. Natural convection dominates transport at all of the conditions investigated.

Citation

Aiche Journal

Volume

50

Issue

9

Pub Type

Journals

Keywords

aqueous solutions, deposition rate model, near-supercritical solutions, potassium sulfate, salt deposition, sodium sulfate, solubility, supercritical water oxidation

Citation

Hodes, M. , Smith, K. , Hurst, W. , Bowers Jr., W. , Griffith, P. and Sako, K. (2004), Salt solubility and deposition in high temperature and pressure aqueous solutions, Aiche Journal (Accessed November 8, 2024)