Computation of Muliticomponent Distillation Processes by the Newton-Raphson Method Using Implicit Function

This paper presents a new iterative method for the rigorous simulation of multicomponent distillation processes. The method employs a Newton-Raphson procedure to solve simultaneous equations and is characterized by the use of liquid compositions as the independent variables and the use of analytical equations for evaluating the partial derivatives. The vapor compositions and the temperatures are chosen as the dependent variables. The analytical equations are derived for the partial derivatives of the vapor compositions with respect to the liquid compositions by using the implicit function theorem. The method has the advantage that numerical evaluation of the partial derivatives and normalization on the liquid compositions are not required. The method exhibits good convergence characteristics for 10 typical distillation examples in complex columns.