Ethylene quench column optimal operation and controllability analysis

The operating conditions for a heat-integrated ethylene quench column are o ptimized and diagnosed for controllability and resiliency. Since a bank of seawater coolers largely meets the column's cooling duty requirements, the heat-exchanger by-pass flow fractions were optimized as a function of seawa ter temperature, using a specially adapted genetic algorithm. The controlla bility and resiliency of the quench column are studied and two alternative MIMO control configurations are investigated. Of particular interest was th e impact of the nominal operating position of the bypass on disturbance rej ection capacity. It was found that the resiliency of the column could be si gnificantly enhanced by repositioning the nominal operating point of the ma in bypass valve and at the same time, the overall heat recovery in the seaw ater coolers could be enhanced, leading to significant savings in operating costs. (C) 2000 IFAC. Published by Elsevier Science Ltd. All rights reserv ed.