Cyclic scheduling and heat integration of batch process: Design of heat storage vessels

Abstract

Scheduling over longer time horizons has limitations such as large problem size and computational complexity. Therefore, there is universal concern to establish novel modeling approaches to efficiently manage various complex characteristics. In this work, a rigorous Unit Specific Event Based model (USEB) is proposed for long-term scheduling of batch plants. The proposed approach addresses the complete scheduling of long-term operational horizon by considering start-up, cycle and finishing periods. The start-up period takes care of intermediate material states requirement at the beginning of first cycle and finishing period effectively utilizes the leftover intermediate states in final cycle. Using active task concept, the cyclic scheduling, direct and indirect heat integration possibilities are accurately modelled by considering design of heat storage vessels. This comprehensive computational approach highlights the importance of judicious use of direct and indirect heat integration in process industries and cyclic scheduling for complex and long term scheduling problems.