(567a) Implementation of an Improved Automatic Operation System for Air Separation Process in Steel Industries

Cryogenic air separation units (ASUs) are widely used for producing gaseous high-purity oxygen in steel industries. As the oxygen demand fluctuates actively in steel manufacturing processes in terms of frequency and amount, the operating condition of ASUs should be accordingly switched rapidly to minimize the waste of oxygen and to save the power consumption in the end. It is thereby financially motivating to develop the automatic operation modification system for ASU. Some studies reported advanced methods such as model predictive control method in the literature. There are many challenges to actually implement such distributed control systems due to the complicating issues of ASUs. They covered the limited snapshot of actual processes. From the hand-on experience, we came to find that it is practically important to introduce simple but straightforward control mechanisms to operate the ASUs in steel industries. This paper proposes a direct approach for the existing control system using parameter tuning based on linear regression of plant data and balanced synchronization between intermediate and final operating target values. Actual case studies of steel industries are conducted in terms of comparing the result according to operator and automatic algorithm for switching operating conditions of varying 15% oxygen production rate. It was found that power consumptions were reduced to 1.4%p for increasing oxygen demand case and 2.4%p for decreasing one.