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Modelling CaSO3/CaSO4 precipitating flow in water treatment devices

Project information

Grant agreement ID: 8916

  • Start date

    1 November 2005

  • End date

    30 April 2007

Funded under:

FP6-MOBILITY

Coordinated by:

VIENNA UNIVERSITY OF TECHNOLOGY

Austria

Objective

The intent of this project is the exploration of thermo- and hydrodynamics of water flows in reverse osmosis membranes and heat exchangers within water treatment plants. Fouling, the attachment or adsorption of substances onto the process equipment, limits heat and mass transfer, thus, the operation of the unit. A major fouling phenomenon in aqueous systems is scale formation due to precipitation of salts in water. Calcium carbonate and calcium sulphate are predominant sparingly soluble salts that are present in the seawater as well as brackish and industrial water systems.

The first emphasis is the set-up of a model yielding consistent sets of thermodynamic properties (heat capacity, density, vapour pressure, osmotic pressure) for the aqueous systems. This model has two answer two purposes: applicability to numerical flow simulation and validity for a wide range of operating conditions - 0 to 100 bar in reverse osmosis membranes and 0 to 150oC in heat exchangers at salinities up to 15 weight percent. Thus, a main effort is the modelling of the effects of varying temperature and pressure on the electrolyte equilibria. The topic of co-precipitation is addressed by differing equilibrium formulations, the range of validity and the applicability of the laws of thermodynamics is investigated. The second emphasis is the implementation of the thermodynamic model into a numerical flow simulation program.

An existing stand-alone flow simulation code provides extensive opportunities to implement the property data and the specific boundary conditions for heat and mass transfer in the devices. The output of the overall simulation is predictions of scaling effects depending on the operating conditions. This knowledge can be used to optimise these conditions as well as the usage of anti-scalants and other pre-processing steps. The information of salt concentrations and the osmotic pressure at the surface of the membrane leads to better assessment of the mass transfer.

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Coordinator

VIENNA UNIVERSITY OF TECHNOLOGY

Address

Karlsplatz 13
Vienna

Austria

Participants (1)

THE UNIVERSITY OF NEW SOUTH WALES

Australia

Project information

Grant agreement ID: 8916

  • Start date

    1 November 2005

  • End date

    30 April 2007

Funded under:

FP6-MOBILITY

Coordinated by:

VIENNA UNIVERSITY OF TECHNOLOGY

Austria