Nonlinear behavior of an ideal reactor separator network with mass recycle
TL;DR: In this paper, the nonlinear behavior of a coupled reactor-separator network is analyzed using singularity and bifurcation theory, and two different modes of operation are considered.
About: This article is published in Chemical Engineering Science.The article was published on 2001-04-01. It has received 65 citations till now. The article focuses on the topics: Continuous stirred-tank reactor & Exothermic reaction.
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TL;DR: By means of the phenol hydrogenation case study, it is shown that indeed the best control strategies are based on manipulating both reactants recycles, and usually, using the recycles to change the production rate is better than fixing the fresh feeds.
59 citations
Book•
17 Sep 2012TL;DR: This paper presents a meta-model for generalized integrated process systems based on Singular perturbation theory, which automates the very labor-intensive and therefore expensive and therefore time-heavy and expensive process management process.
Abstract: Part I. Preliminaries: 1. Introduction 2. Singular perturbation theory Part II. Process Systems with Material Integration: 3. Process systems with significant material recycling 4. Process systems with purge streams 5. Dynamics and control of generalized integrated process systems Part III. Process Systems with Energy Integration: 6. Process systems with energy recycling 7. Process systems with high energy throughput References Part IV. Appendices: A. Definitions B. Systems with multiple time scale dynamics C. MATLAB code.
57 citations
TL;DR: In this article, it was shown that the presence of the small purge stream leads to a time scale separation in the dynamics of the network and a method was proposed for the derivation of nonstiff, reduced-order models in each time scale that are suitable for analysis and model-based control.
Abstract: This work concerns the dynamics and control of process networks in which impurities are present and are removed by a small purge stream. Using a singular perturbation analysis, it is shown that the presence of the small purge stream leads to a time scale separation in the dynamics of the network. A method is proposed for the derivation of nonstiff, reduced-order models in each time scale that are suitable for analysis and model-based control. Finally, two case studies are introduced and illustrative numerical simulation results are provided. © 2006 American Institute of Chemical Engineers AIChE J, 2006
52 citations
TL;DR: In this paper, the multiplicity behavior of six reaction systems of increasing complexity, from one-reactant, first-order reaction to chain-growth polymerisation, is investigated, and the achievable conversion is constrained by the instability of the low-conversion branch.
50 citations
Cites background from "Nonlinear behavior of an ideal reac..."
...Recently, Pushpavanam and Kienle (2001) considered an exothermic 7rst-order reaction in a CSTR–separator (instantaneous 8ash)–recycle system....
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TL;DR: In this article, the authors analyzed the nonlinear behavior of several recycle systems involving first-and second-order reactions and demonstrated that a particular location for fixing the recycle flow rate is advantageous, namely, the reactor inlet.
Abstract: This paper analyzes the nonlinear behavior of several recycle systems involving first- and second-order reactions. The results, presented in term of dimensionless numbers, explain some control difficulties reported by previous studies. It is shown that conventional control structures, fixing the flow rate of fresh reactants and relying on self-regulation, can lead to parametric sensitivity, unfeasibility, state multiplicity, or instability, particularly at low conversions. These problems can be solved by fixing the flow rate in the recycle loop, as stated by Luyben's rule. This paper demonstrates that a particular location for fixing the recycle flow rate is advantageous, namely, the reactor inlet. This decouples the reactor from the rest of the plant and avoids undesired phenomena due to mass recycles. For example, the unstable closed-loop behavior observed with nonisothermal PFRs disappears. The HDA plant case study illustrates the proposed strategy.
49 citations
References
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01 Jan 1985
TL;DR: Singularities and groups in bifurcation theory as mentioned in this paper have been used to solve the problem of finding a group of singularities in a set of problems with multiple solutions.
Abstract: This book has been written in a frankly partisian spirit-we believe that singularity theory offers an extremely useful approach to bifurcation prob- lems and we hope to convert the reader to this view In this preface we will discuss what we feel are the strengths of the singularity theory approach This discussion then Ieads naturally into a discussion of the contents of the book and the prerequisites for reading it Let us emphasize that our principal contribution in this area has been to apply pre-existing techniques from singularity theory, especially unfolding theory and classification theory, to bifurcation problems Many ofthe ideas in this part of singularity theory were originally proposed by Rene Thom; the subject was then developed rigorously by John Matherand extended by V I Arnold In applying this material to bifurcation problems, we were greatly encouraged by how weil the mathematical ideas of singularity theory meshed with the questions addressed by bifurcation theory Concerning our title, Singularities and Groups in Bifurcation Theory, it should be mentioned that the present text is the first volume in a two-volume sequence In this volume our emphasis is on singularity theory, with group theory playing a subordinate role In Volume II the emphasis will be more balanced Having made these remarks, Iet us set the context for the discussion of the strengths of the singularity theory approach to bifurcation As we use the term, bifurcation theory is the study of equations with multiple solutions
3,214 citations
TL;DR: In this article, the types of dynamic behavior possible for a single first order reaction carried out in a stirred tank reaction are classified according to values of the parameters and plots in parameter space used to define the various possibilites.
655 citations
Book•
01 Aug 1996
TL;DR: In this paper, the authors present practical aspects of process control, including sizing control valves, tuning controllers, developing control structures and considering interaction between plant design and control, as well as real industrial control examples and problems.
Abstract: Intended for undergraduates, this text covers those area of process control that all chemical engineers need to know. Analysis of closed loop dynamics in the time, Laplace, frequency and sample-data domains are covered. Designing simple regulatory control systems for multivariable processes are also discussed. The practical aspects of process control are presented: sizing control valves, tuning controllers, developing control structures and considering interaction between plant design and control. The book includes many real industrial control examples and problems.
197 citations
TL;DR: In this paper, a systematic, efficient scheme is presented for finding parameter values corresponding to a specific number of solutions. But this scheme is not suitable for large-scale systems, where many chemical reactions occur simultaneously with a large number of parameters.
157 citations
TL;DR: In this article, the effect of material recycle and heat integration on the dynamics and control of chemical processing plants is considered, and the authors consider how plant interconnections affect the fundamental properties of the dynamics, such as the poles and zeros.
66 citations