A large paper mill forms a complex energy flow because of highly intensive usage of energy. These energy flows are interdependent each other, furthermore, there is a recycling delay of liquor in the process. This means the plant optimization problem should be treated as a dynamical one. As a result, it becomes a very large scale optimization problem. To solve this problem in high speed, we
... [Show full abstract] propose an optimization method which is based on a basis factorization method. This is devised to use the special staircase structure of the constraint equations. Four days (96 hours) scheduling with about 3500 variables is performed in about 10 minutes by a process computer. This reduction of computing time enables the process computer to control the process and to get an adequate operational guidance for a plant operator simultaneously. By this adequate guidance it is expected to cut down the total energy cost for the process by about 2%.
