A new computation procedure is proposed for multicomponent distillation columns processing non-ideal solutions. The Newton-Raphson method in whichliquid mole fractions are chosen as independent variables is used to solve the tridiagonal matrix equation

and a block tridiagonal matrix algorithm is developed. Successful applications of the new method to some non-ideal distillation systems are demonstrated with features of more insensitiveness to the initial values fewer C. P. U. memories

fewer partial derivatives more rapid and more stable than others.