Quantification of process flexibility via space projection. Issue 10 (22nd June 2019)

• Record Type: Journal Article
• Authors: Zhao, Fei; Zheng, Chenglin; Zhang, Shuhui; Zhu, Lingyu; Chen, Xi
• Is Part Of: AIChE journal. Volume 65:Issue 10(2019)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-06-22
• Subjects: cylindrical algebraic decomposition -- flexibility analysis -- flexibility index -- process design -- quantifier elimination; Chemical engineering -- Periodicals; Génie chimique -- Périodiques; 660.28
• DOI: 10.1002/aic.16706
• Languages: English
• ISSNs: 0001-1541

Abstract

Abstract: Flexibility index is an effective indicator for characterizing the operational flexibility of a process design model. In this work, the concept of δ ‐space projection is proposed and defined from the view of solution space, and the flexibility index can be quantified without solving any optimization problems. First, the flexibility index problem is reformulated as an existential quantifier model. Then, the projection operator in the cylindrical algebraic decomposition (CAD) method is introduced to project the solution space onto the one‐dimensional feasible space of the flexibility index. Subsequently, all the candidate values of the flexibility index, which may refer to the locations of the critical points, that is, vertexes and tangency points, are extracted. Last, two δ ‐checking rules based on the traditional and improved CAD methods are proposed for finding the flexibility index. The case studies show that the proposed method can exactly find the flexibility index, regardless of convex or nonconvex systems.