Abstract: The whole margin of a chemical process can be evaluated by the economic benefits of operation optimization, and based on steady-state optimization and dynamic optimization it can be further divided into control margin for dynamic operation and process margin for achievable economic benefits, both of which are relevant to control performance of the chemical process. In this paper, multi-objective dynamic optimization was implemented for a chemical process with design margin, whose optimization objectives were the achievable economic benefits of operating point and the control performance of dynamic process. The control structure described by 0-1 variables and control parameters were the optimization variables to form a mixed-integer dynamic optimization. Constrained NSGA-Ⅱ was used to solve the multi-objective dynamic optimization problem. Based on the Pareto optimal solution set, the relationship between control margin, process margin and control performance was analyzed. The case study of FCCU showed that, for a chemical process with design margin, when control performance was improved, the process would need more control margin but less process margin, which meant less achievable economic benefits from operation optimization. Through the trade-off between control margin and process margin, an optimum operating point and control scheme could be found to fulfill both process and control demand.

Key words: whole margin, control performance, operation optimization, multi-objective optimizationn

摘要： 化工过程的总体裕量可以用操作优化的经济效益进行评价，根据稳态优化和动态优化的经济效益可进一步划分为服务于操作控制的控制裕量和表征过程可实现经济效益的工艺裕量，二者都与化工过程的控制性能有关。针对具有一定裕量的化工过程进行多目标动态优化，优化目标分别为操作点的经济效益与动态过程中的控制性能指标，采用0-1变量描述控制结构，将控制结构和控制器参数也作为优化变量进行混合整数动态优化，采用Constrained NSGA-Ⅱ算法求解非劣解集，根据非劣解集分析总体工艺裕量、总体控制裕量与控制性能指标的关系。通过催化裂化装置的实例分析发现，对于具有一定裕量的化工过程，控制性能越高，所需的总体控制裕量越多，表征操作优化可实现经济效益的总体工艺裕量越少，只有通过对总体控制裕量和总体工艺裕量进行权衡，才能找到兼顾工艺要求和控制性能的工艺操作点和控制设计方案。

关键词: 总体裕量, 控制性能, 操作优化, 多目标优化