HYDRAULIC DESIGN OPTIMIZATION OF ELECTRODIALYSIS FOR DEMINERALIZING BRACKISH WATERS
Titel:
HYDRAULIC DESIGN OPTIMIZATION OF ELECTRODIALYSIS FOR DEMINERALIZING BRACKISH WATERS
Auteur:
Harrington, Joseph J. Smith, J. Douglas
Verschenen in:
Engineering optimization
Paginering:
Jaargang 2 (1977) nr. 4 pagina's 257-267
Jaar:
1977
Inhoud:
Conventional electrodialysis process design is largely empirical, requiring either experimental determination or previous experience with closely similar conditions. Formal cost minimization is not usually considered. This paper presents a non-linear programming model, with a posynomial cost function, subject to a number of hydraulic,-physicalchemical, and other constraints. The cost function includes terms proportioned to membrane area, D.C. power and pumping power. The hydraulic characteristics of electrodialysis spacers arc modelled as a packed-column, or Ergun-type expression, based on the summation of separate laminar and turbulent flow components. The laminar component is a modified Hagen-Poiseuille equation for flow through circular tubes; and the turbulent component is a modified Darcy-Weisbach equation for flow in closed conduits. Constraints arise from considerations of calcium sulfate solubility, limitations on available materials for spacers, and concentration (expressed in terms of limiting current density). The problem is transformed into geometric programming formats, which are solved numerically for optimal designs. The model may be used to evaluate research and development policies aimed at improving membrane characteristics, spacer configurations and the like. Results include not only-estimates of cost reductions associated with given policies, but also how the designs would change in response to changes in technological and/or economic parameters.
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