Some algorithms applied to solve problems of distillation in which heat duty of the reboiler or the condenser is specified, but the reflux ratio is not, are discussed. A useful and flexible algorithm is presented, in which an existing computer program for an operating column analysis is employed without change, and a useful correction loop for the reflux ratio is added externally. This loop is obtained from the relationship between the reflux ratio and an overall energy balance. This algorithm is readily applied because it is independent of the calculation technique used with an existing computer program. Numerical examples indicate the effectiveness and reliability of this algorithm.