Identification of critical points for the design and synthesis of flexible processes

Zorka Novak-Pintarič (Author), Zdravko Kravanja (Author)

Abstract

Optimization problems for the design and synthesis of flexible chemical processes are often associated with highly discretized models. The ultimate goal of this work is to significantly reduce the set of uncertain parameter points used in these problems. To accomplish the task, an approach was developed for identifying the minimum set of critical points needed for flexible design. Critical points in this work represent those values of uncertain parameters that determine optimal overdesign of process, so that feasible operation is assured within the specified domain of uncertain parameters. The proposed approach identifies critical values of uncertain parameters a-priori by the separate maximization of each design variable, together with simultaneous optimization of the economic objective function. During this procedure, uncertain parameters are transformed into continuous variables. Three alternative methods are proposed within this approach: the formulation based on Karush-Kuhn-Tucker (KKT) optimality conditions, the iterative two-level method, and the approximate one-level method. The identified critical points are then used for the discretization of infinite uncertain problems, in order to obtain the design with the optimum objective function and flexibility index at unity. All three methods can identify vertex or even nonvertex critical points, whose total number is less than or equal to the number of design variables, which represents a significant reduction in the problem's dimensionality. Some examples are presented illustrating the applicability and efficiency of the proposed approach, as well as the role of the critical points in the optimization of design problems under uncertainty.

Keywords

kemijska procesna tehnika;sinteza procesov;fleksibilnost;načrtovanje;kritične točke;chemical processing;process synthesis;flexibility;design;critical point;vertex;nonvertex;

Data

Language:	English
Year of publishing:	2008
Typology:	1.01 - Original Scientific Article
Organization:	UM FKKT - Faculty of Chemistry and Chemical Engineering
UDC:	66.02:519.61/.64
COBISS:	11658518
ISSN:	0098-1354
Views:	1477
Downloads:	81
Average score:	0 (0 votes)
Metadata:

Other data

Secondary language:	English
Secondary keywords:	kemijska procesna tehnika;sinteza procesov;fleksibilnost;načrtovanje;kritične točke;
URN:	URN:SI:UM:
Pages:	str. 1603-1624
Volume:	ǂVol. ǂ32
Issue:	ǂiss. ǂ7
Chronology:	July 2008
DOI:	10.1016/j.compchemeng.2007.08.003
ID:	8718585