FROM UNIFAC TO MODIFIED UNIFAC TO PSRK WITH THE HELP OF DDB

A reliable knowledge of the phase equilibrium behavior of the system t o be separated is a prerequisite for the synthesis, design and optimiz ation of separation processes. This behavior can be calculated with th e help of g(E) models and equations of state using binary data alone. When no experimental data are available, group contribution methods (A SOG, UNIFAC, modified UNIFAC, PSRK) can be successfully applied. For a ll these group contribution methods the Dortmund Data Bank (DDB) was u sed for fitting the required group interaction parameters. In this pap er the present status of the different models will be shown and their advantages and disadvantages will be discussed. After a demonstration of typical results, the application for the synthesis of separation pr ocesses and an outlook on future developments will be given. Furthermo re the importance of the Dortmund Data Bank and the integrated softwar e packages for the development of reliable models with a large range o f applicability and the application for the synthesis of separation pr ocesses will be demonstrated.