An Aqueous Phase Equilibrium Calculation Algorithm

A multiphase chemical equilibrium algorithm is developed which can be used with aqueous systems. The algorithm uses an average chemical potential for each species as a reference chemical potential. Incipient phases can be identified and their proximity to appearance can be determined through their t...

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Bibliographic Details
Published in:Canadian journal of chemical engineering 2002-08, Vol.80 (4), p.741-752
Main Authors: Makkuni, Ajay, Phoenix, Aaron V., Rohani, Sohrab
Format: Article
Language:English
Subjects:
aqueous solution
Chemistry
computation
Exact sciences and technology
General and physical chemistry
Others (including liquid-liquid-vapor equilibria)
Phase equilibria
reaction equilibria
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Summary:A multiphase chemical equilibrium algorithm is developed which can be used with aqueous systems. The algorithm uses an average chemical potential for each species as a reference chemical potential. Incipient phases can be identified and their proximity to appearance can be determined through their tangent plane distance. Illustrative examples include the calculation of CaSO4 solubility and the calculation of vapour pressures above an SO2‐NaCl‐H2O system, including the prediction of a three‐phase equilibrium. The algorithm proved robust and versatile. The appearance of incipient phases was easily tracked. Future work needs to be done to optimize damping/acceleration coefficients in the calculations. On a établi un algorithme d'équilibre chimique polyphasique pouvant servir à des systèmes aqueux. L'algorithme utilise un potentiel chimique moyen pour chaque espèce comme potentiel chimique de référence. Des phases à l'état embryonnaire peuvent être identifiées et la proximité de leur apparition peut se déterminer à travers leur distance plane tangente. Les illustrations données à titre d'exemples comprennent le calcul de la solubilité du CaSO4 et le calcul des pressions de vapeur au‐dessus d'un système SO2‐NaCI‐H2O, uncluant la prédiction d'un équilibre triphasique. L'algorithme s'avère robuste et polyvalent. D'autres travaux sont nécessaires pour optimiser les coefficients d'amortissement/accélérations dans les calculs.
ISSN:0008-4034
1939-019X
DOI:10.1002/cjce.5450800427