Optimal Scheduling Of Parallel Distillation Systems With Multiple Product Grades

Optimal scheduling of parallel units systems with multiple grades is an important topic in process industry.Reasonable production scheduling can reduce production costs,save energy and improve the production capacity of enterprises.It is an essential part to establish an effective scheduling mode,to find an appropriate solution method,and to obtain a reasonable optimal scheduling for the production system.In this paper,an optimal scheduling model is developed for parallel distillation systems with multiple product grades.The detailed work can be summarized as follows:1.Derived surrogate models from rigorous models for distillation columns.First,rigorous nonlinear models are built for each distillation column and validated with plant data.Based on the rigorous models,optimal operating points for various conditions,which are used to build a surrogate model for each column,are obtained;the conditions include relationships between feed and production and relationships between energy consumption and production.2.Formulated an MILP scheduling model for multiproduct distillation systems.The model describes various constraints in the production processing,including material balance,surrogate model of distillation columns,mode transition,boundary conditions.3.Applied framework to a real-world industrial fine chemical production system.Firstly,the optimal scheduling is compared with two heuristic scheduling results.Then,the influence of the discretization step on the final results is explored.At last,the accuracy of the result of scheduling based on reduced-order model of distillation is analyzed.Finally,summary of the paper is presented along with prospect of future work.