Fluid Phase Equilibria 194–197 (2002) 783–803 Conceptual design and analysis methodology for crystallization processes with electrolyte systems Kiyoteru Takano a,1 , Rafiqul Gani a,∗ , Takeshi Ishikawa b , Petr Kolar c a CAPEC, Department of Chemical Engineering, Technical University of Denmark, DK-2800, Lyngby, Denmark b Yokohama Research Center, Mitsubishi Chemical Corporation, 1000 Kamoshida-cho, Aoba-ku, Yokohama, 227-8502, Japan c Mitsubishi Chemical Corporation, Ushiodori 3-10, Kurashiki, Okayama, Japan Received 20 May 2001; accepted 6 September 2001 Abstract A methodology for multi-level conceptual design and analysis of crystallization-based separation processes involving electrolyte systems is presented. The methodology consists of three main parts: thermodynamic part (level 1), flowsheet design/analysis part (level 2) and flowsheet validation (simulation) part (level 3). In this paper, the integration of the thermodynamic and design/analysis parts is presented. This integration allows the analysis of the thermodynamic behavior of a given system together with design/analysis of flowsheet alternatives in the same calculation environment. The integrated system is highlighted through four practical examples where features of the algorithm related to creation of property model package and its usage in flowsheet design/analysis are highlighted. © 2002 Elsevier Science B.V. All rights reserved. Keywords: Crystallization; Electrolyte system; Method of calculation; Solid–fluid equilibria; Model; Design 1. Introduction Solution chemistry and solid–liquid (phase) equilibrium play a very important role in design, synthesis and analysis of crystallization-based separation processes involving electrolytes. The solid–liquid equilib- rium (SLE)-phase diagrams can be used to identify the feasible operation paths for a desired product from a specified feed mixture. They also help to identify the separation boundaries, the condition of operation (such as temperature of operation), the list of solids that are most likely to precipitate and many more. In- formation from the generated SLE-phase diagrams, such as phase boundary data and saturation point data, may be used to solve graphically the mass balance equations related to a crystallization operation. Since the graphical solution of the mass balance equations is related to the operational paths on the phase diagrams, ∗ Corresponding author. E-mail addresses: takanok@rc.m-kagaku.co.jp (K. Takano), rag@kt.dtu.dk (R. Gani). 1 Present address: On leave from Yokohama Research Centre, Mistubishi Chemical Corporation, 1000 Kamoshida-cho, Aoba-ku, Yokohama, Japan. Tel.: +81-45-963-3269; fax: +81-45-963-3947. 0378-3812/02/$ – see front matter © 2002 Elsevier Science B.V. All rights reserved. PII:S0378-3812(01)00705-1