A hierarchical scheduled optimization and control for minimizing production cost and energy consumption of CSTR

For traditional chemical process industry, the main aims of production in most processes are to promote quality of productivity and to maximizing economic profits, but fewer works strive to reduce energy consumption through optimal production schedule and optimal process operation. In this study, a hierarchical scheduled optimal and control strategy for continuous flow stirred tank reactor(CSTR) operation is presented in detail. A performance index is used to minimize total energy consumption, other than maximize profit. Meanwhile, production schedule optimization is combined with optimal process operation based on taking the presence of ever-changing external influences into account, such as changing raw material prices in marketplace, the depreciation cost of main equipments and servicing facilities, wages of workers, utilities cost for the premise condition. The optimal setpoints of key variables in process are derived from top production schedule optimization layer, and optimal process operation which model predictive control algorithm is implemented at lower optimal process control operation layer. The effects of production factors on the total energy consumption are analyzed. The effectiveness of this method is demonstrated by CSTR case study.