I. Molecular Simulations of Water and Steam II. Hazardous Waste Treatment: Supercritical Water Oxidation I. Molecular Simulations of Water and Steam II. Hazardous Waste Treatment: Supercritical Water Oxidation Igor Svishchev Trent University, Peterborough, ON IAPWS-CNC 2003 IAPWS-CNC 2003

Key applications: Thermal properties of aqueous fluids under extreme conditions Nucleation rates in metastable steam Solubilities of salts at elevated temperatures and pressures Partition coefficients Advantages: Cost and time savings over laboratory measurements Replaces empirical extrapolations and fits IAPWS Simulation Task Group: Promotes modeling of aqueous fluids relevant to power cycles and other industrial applications, and provides an international forum for exchange of results of research (PVT databases, analytical fits, computer programs). Molecular Simulation: Industry Connections

Properties of Working Fluids: “Releases provide carefully evaluated, internationally agreed-upon formulations of properties for which measurement of high quality exist over a wide range of states”. “Guidelines are carefully evaluated, internationally agreed-upon formulations of properties for which measurement of high quality do not exist over a wide range of states or can not be made”. International Association for the Properties of Water and Steam, 1994 IAPWS Releases and Guidelines Real FluidSimulated Fluid ? Where do the standards come from ?

Molecular Models: Molecular Models: water and oxygen Starting point

Molecular Simulation: liquid water Computer Experiment

Simulated PVT database: Simulated PVT database: water and steam Outcome

Equation of State: Equation of State: Pitzer-Sterner EOS Critical Point for Water:T c, KP c, bar  c, g/cm 3 IAPWS Release, Pitzer-Sterner EOS, Analytical fit

Analytical fit: Analytical fit: PVT surface for simulated water Pressure, bar Best fit Pitzer-Sterner EOS 27 fitting coefficients Svishchev and Hayward, 2001

Water-Oxygen Mixtures: Water-Oxygen Mixtures: Simulations and EOS Analytical fits for simulated PVT data - EOS for the mixture (  ) has the same form as for pure solvent, water ( component  ), - Mixture parameters are derived from the parameters of the single-component EOS c 1 (  ) = x 2 (  ) c 1 (  ) +x 2 (  ) c 1 (  ) + x(  ) x(  ) [c 1 (  ) + c 1 (  )] (1-k), x - mole fraction of O 2 c (  ) = x(  ) c (  Note : k is the only “coupling” parameter, independent of T and 

Water-Oxygen Mixtures: Water-Oxygen Mixtures: results Comparison with Experiment (6 % O 2, T=645 K,  =0.32 g/cm 3 ) Exp., Franck, 1985 Simulated EOS P ~ 300 bar P = 296 bar Simulated EOS (water + 5% O 2 )

Phase diagram for water Supercritical Water Oxidation: Supercritical Water Oxidation: basics Supercritical Water Oxidation P>221 bar, T > 647K Wet Air Oxidation P~ 200 bar T= K Purpose: Total destruction of organic wastes by chemical oxidation in supercritical water Features: - rapid and effective process - environmentally safe - eliminates residual salts (radioactivity) Customers: - chemical plants, paper mills - power utilities - military facilities

Oxidation reactions in supercritical water Supercritical Water Oxidation: reactions

SCWO process Reactor Schematic Reactor: Stainless Steel 316 V = 3.74 cm 3 P = 450 bar 2.4 ml/min 0.6 ml/min 3.0 ml/min t r = 75 s Reagents: Aqueous dichlorobenzene Oxidizer: Aqueous H 2 O 2

Supercritical Water Oxidation: results chlorophenol dichlorophenol Temperature effect on degradation efficiency at 450 bar 3.6 ppm 0.87 ppm 1.14 ppm 1.03 ppm 0.09 ppm Wet air Supercritical water

Thank You Acknowledgements: NSERC T. Hayward A. Plugatyr