Nonlinear analysis in process design. Why overdesign to avoid complex nonlinearities?

Seider, Warren D.; Brengel, David D.; Provost, Alden M.; Widagdo, Soemantri

doi:10.1021/ie00101a016

Cited by 52 publications

(34 citation statements)

References 40 publications

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“…This is the case for a simple CSTR in which open-loop bifurcations and pathologies are effectively eliminated by simple proportional control (Aris and Amundson, 1958). Similarly, theoretical studies suggest that accurate nonlinear model-based control can lead to safe operation of packed bed reactors near regions of parametric sensitivity (Seider et al, 1990). However, as we will see in this section, there are certain complicating features of an industrial packed-bed reactor which do not allow even an advanced control scheme to eradicate the sensitive open-loop behavior.…”

Section: Control Issues For Tubular Reactor Designmentioning

confidence: 95%

“…In principle, the same stabilization theory can be invoked for a packed-bed reactor, and safe closed-loop operation can be attained in a region of open-loop sensitivity (see, for example, Seider et al, 1990). A number of experimental studies have also focused on the stabilizing effects of feedback control in a single tube reactor (Hansen and Jorgensen, 1976 Tremblay and Wright, 1974).…”

Section: Introductionmentioning

confidence: 99%

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Design considerations for tubular reactors with highly exothermic reactions

et al. 1992

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Section: Control Issues For Tubular Reactor Designmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Design considerations for tubular reactors with highly exothermic reactions

et al. 1992

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“…First, some researchers consider that nonlinear behavior should not be moved or avoided, and controllability and nonlinear analysis is not necessary as many complex nonlinear behaviors can be efficiently dealt with and the system can be operated around optimal nonlinear operating regions by proper nonlinear control algorithms like the nonlinear model predictive control (NMPC) algorithm. 39 This may be true for controller design but is not satisfactory for analyzing the controllability of a chemical process. Second, some researchers highlight that it is important for analyzing the controllability of a system to identify and assess all potential operability problems associated with the complex behavior when the alternatives are considered during the design stage.…”

Section: Discussionmentioning

confidence: 99%

Phase behavior analysis for industrial polymerization reactors

2010

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The production of polymer is a very important sector in the chemical processing industry as demand for polymeric materials increases, and these polymerization processes exhibit nonlinear dynamics posing difficulties on process operation and control. It is desirable to understand the relationship between open-loop controllability and process conditions. The phase behavior that is an open-loop indicator of the controllability for the methyl methacrylate and propylene polymerization reactor over the entire feasible operating region is determined, and the influences of design/operating parameters and model uncertainties on this inherent characteristic at the design stage are analyzed. Based on zero dynamics and singularity theory, directly in the nonlinear setting, a methodology for the preliminary analysis of the phase behavior over the whole feasible operating region is presented and applied into the above two reactors.The above research results demonstrate that to modify certain parameters in certain direction would improve the controllability and are expected to provide helpful guidelines for improving plant and control system design. This is desirable because it allows identification of the cause of the limitation to give an indication where to modify the design.

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“…The potential control problems associated with these characteristics could be eliminated or avoided by modifying the process design itself. 75 Although many complex nonlinear behaviors can be efficiently dealt with using modern control algorithms like the nonlinear model predictive control (NMPC) algorithm, 76,77 it is important for analyzing the controllability of a system to fully identify all potential problems associated with the complex behavior and to assess how easy the design is to control when the alternatives are considered during the design stage. 78 The existing nonlinear controllability analysis methods can be divided into those which are analytical and those which are optimization based.…”

Section: Controllability Analysis For Nonlinear Processesmentioning

confidence: 99%

An overview on controllability analysis of chemical processes

2011

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Controllability is one of the most important aspects of chemical process operability, because it can be used to assess the attainable operation of a given process and improve its dynamic performance. The purpose of this article is to outline the main methodologies that have been developed to deal with the assessment of process controllability and the improvement of its controllability characteristics. Several existing controllability assessment methods are reviewed and discussed. For improving the controllability characteristic of a process, there are two main design methods: the optimization-based method and the controllability indices-based anticipating sequential method. Advantages and disadvantages of these techniques are discussed. It has been emphasized that bifurcation analysis, as a powerful nonlinear analysis tool, could provide important guidance for making processes more controllable by eliminating or avoiding some undesirable behaviors of processes. Further challenges and developments in the field of process controllability are identified.

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Nonlinear analysis in process design. Why overdesign to avoid complex nonlinearities?

Cited by 52 publications

References 40 publications

Design considerations for tubular reactors with highly exothermic reactions

Design considerations for tubular reactors with highly exothermic reactions

Phase behavior analysis for industrial polymerization reactors

An overview on controllability analysis of chemical processes

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