Lin J.-J., Xu F., Luo X.-L., 2019, Dynamic Optimization of Continuous Chemical Process with Batch Operation Variable: A Case Study of a Fluid Catalytic Cracking Unit with CO Promoter, Chemical Engineering Transactions, 76, 751-756.
Continuous chemical process will formulate a hybrid system when introducing batch operation. The optimisation of such systems requires dynamic optimisation with control parameters. Considering the complexity of engineering problems, it is usually solved by a direct method such as control vector parameterization (CVP), which reformulates the primal problem into a nonlinear programming problem (NLP). In detail, the continuous control variables are approximated by functions with finite parameters. The strategy is verified by the case study of a Fluid Catalytic Cracking Unit (FCCU) with CO promoter. An augmented dynamic model of an FCCU with high-efficiency regenerator is developed incorporating the quantitative correlation between average activity of CO promoters and the number of added CO promoters. By simulation, it’s found that the nominal operating conditions can only ensure safety performance, while the economic performance is neglected for the lack of exploiting the safety margin. The optimisation problem is solved by different kinds of approximation functions, which improves the solution of dynamic optimization problem. The result shows that tuning the continuous control variables across time according to optimized batch control variables obviously increases the economic performance during preserving safety.
