| Autor: |
Fournier, R. L., Boston, J. F. |
| Zdroj: |
Chemical Engineering Communications; January 1981, Vol. 8 Issue: 4 p305-326, 22p |
| Abstrakt: |
A new algorithm has been developed for solving the multicomponent vapor-liquid-liquid equilibrium Mash problem. The algorithm is an extension of the "inside-out" approach proposed by Boston and Britt for the vapor-liquid equilibrium flash problem.Conventional flash algorithms use temperature, pressure, composition, and phase fraction as the problem independent variables, In the inside-out approach a new set of independent variables is introduced in place of the conventional variables. The new variables are chosen to be as independent as possible of the conventional variables and as free as possible of mutual interaction. Complex phase equilibrium models are used only to generate parameters for a simple equilibrium ratio model. These parameters become the problem independent variables. The Quasi-Newton method of Broyden is employed to promote convergence of these variables.The algorithm first obtains a solution for the vapor-liquid equilibrium flash. By examining the liquid phase, a heuristic algorithm is employed which quickly locates a two liquid phase composition region of reduced total system free energy when the original liquid is unstable. The solution of the vapor-liquid-liquid equilibrium flash is initiated only when this occurs.The performance of the algorithm is demonstrated by a number of problems which exhibit varying degrees of nonideality. |
| Databáze: |
Supplemental Index |
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