Analysis of the energy consumption of supercritical water desalination (SCWD)

Surika van Wyk, Aloijsius G.J. van der Ham, Sascha R.A. Kersten*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

1 Citation (Scopus)
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Abstract

An experimental and modelling study was done to investigate supercritical water desalination (SCWD) with respect to energy consumption as a function of the NaCl concentration (0 to 20 wt%). Pilot plant experiments were performed for different flow rates and feed concentrations, and used for the validation of the thermodynamic models (eNRTL and Anderko & Pitzer) employed for phase equilibria and enthalpy calculations. Experimental and modelling results showed that the lowered heat capacity of the feed streams, while increasing the concentration from 0 to 7 wt%, leads to improved performance of the feed - supercritical water (SCW) heat exchanger (HEX), evident from a higher feed outlet temperature. For concentrations of ≥14 wt%, pre-heating of the feed, prior to the HEX, is recommended due to the decrease in the SCW recovery in the SCW-brine separator. The calculated duty, of the heater bringing the heat-exchanged feed to the separation temperature, decreases with NaCl concentration due to the decrease in the feed heat capacity. The calculated overall energy consumption of SCWD was between 0.71 and 0.90 MJth/kgfeed. For higher concentration feeds, the energy input is divided between low – and high quality (temperature) heat.

Original languageEnglish
Article number114189
JournalDesalination
Volume474
Early online date30 Oct 2019
DOIs
Publication statusPublished - 15 Jan 2020

Keywords

  • UT-Hybrid-D
  • Process modelling
  • Supercritical water desalination (SCWD)
  • Thermodynamics
  • Pilot plant validation

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