Steady state chemical process simulation

Motard, R. L.; Shacham, Mordechai; Rosen, Edward M.

doi:10.1002/aic.690210302

Cited by 88 publications

(14 citation statements)

References 34 publications

(35 reference statements)

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“…tion or optimization is being carried out. The required information may be entered in a variety of ways (Motard et al, 1975). In SIMMOD this information is entered using a problem oriented language (POL) in a logical order.…”

Section: Convergence Criteriamentioning

confidence: 99%

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A simultaneous‐modular approach to process flowsheeting and optimization. Part I: Theory and implementation

Chen

Stadtherr

1985

AIChE Journal

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Three basic problem formulations for the simultaneous-modular approach are discussed, as are three alternative methods for computing the flowsheet-level Jacobian. A new algorithm for partitioning and tearing when using the Simultaneous-modular approach is also presented. SIMMOD, our implementation of the simultaneous-modular approach is then outlined. In subsequent papers in this series we use SIMMOD to study the performance of the simultaneous-modular approach on process simulation and optimization problems, as well as to perform experiments on different numerical strategies for implementing the simultaneous-modular approach.

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Section: Convergence Criteriamentioning

confidence: 99%

“…It should be noted at the outset that several extensive reviews of work in process flowsheeting have appeared in recent years, including reviews by Motard et al (1975), Hlavacek (1977), Rosen (1980), and Evans (1981). The monograph of Westerberg et al (1979) provides a good introduction to this field.…”

Section: Introductionmentioning

confidence: 99%

A simultaneous‐modular approach to process flowsheeting and optimization. Part I: Theory and implementation

Chen

Stadtherr

1985

AIChE Journal

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“…The literature abounds with algorithms to find the "tear" streams automatically for process flowsheeting calculations. A review article by Motard, Shacham and Rosen (1975) discusses most such algorithms. In a flowsheeting calculation, n equations, such as the heat and material balance relationship, equilibrium and rate relationships, are solved for a process flowsheet to yield values for an equal number of unknowns such as temperatures, pressures, flows and stream compositions.…”

Section: Scopementioning

confidence: 99%

Exclusive tear sets for flowsheets

Motard

Westerberg

1981

AIChE Journal

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Wfe shall show in this paper that the nonredundant family of tear sets is directly related to the unique tearing of unit loops within the flowsheet. We shall discover that the inability to find a tear set which tears all unit loops exactly one time gives rise to more than one nonredundant family in the Upadhye and Grens sense. Such a discovery allows us to distinguish among nonredundant families and argue qualitatively that some of these should have better convergence properties than others.

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“…A voluminous literature exists on various algorithms for carrying out all or portions of these three analysis stages. Some of the more recent advances can be found in the papers of Barkley and hlotard (1972), Uphadye and Grens (1972), Pho and Lapidus (1973), Motard et al ( 1975), and Genna and Motard ( 1975).…”

Section: Conventional Solution Strategies For Umbpmentioning

confidence: 99%

Solution of material balances for flowsheets modelled with elementary modules: The unconstrained case

1979

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A study is made of the structure and properties of material balance simulation problems, and a technique is developed for their efficient solution. The method requires neither simultaneous solution of all balance equations nor iterative convergence methods. Instead, for each stream mixing point in the flow sheet, a vector balance equation is developed which contains as unknowns only mixer output streams. This unique set of vector equations is sequenced for solution by using precedence ordering and substitution techniques. It is shown that only as many vector equations need to be solved simultaneously as there are streams which would require iteration in the conventional sequential approach. SCOPEThe solution of material balances for large scale process flow sheets without the incorporation of detailed unit operations models is a basic chemical engineering problem of considerable practical importance both in preliminary design and in the study of existing plants. Three computer oriented strategies for solving flow sheet material balances have been reported or are in use at the present time: the completely simultaneous approach, the recycle stream iteration approach, and the split-stream approach of Rosen-Nagiev (Rojen, 1962). All of these approaches employ a representation of flow sheets in terms of a fixed repertoire of standard models which are linear in the stream flows. The simultaneous solution method necessitates assembly and storage of very large equation sets, requires the use of sparse matrix techniques, and does not directly exploit the inherent network structure of flow sheets in which species flows are aggregated into streams. The recycle iteration approach requires the selection of streams to be estimated and iterated upon and necessitates time consuming iterations with uncertain convergence. The Rosen-Nagiev technique uses simultaneous solution of the sets of material balances written around each stream mixing point aggregated by species. In general, in the presence of reactions, the species balances become coupled, and the entire system of sets of equations must be solved in iterative passes.Recognizing that the material balance simulation problem is inherently a highly structured linear problem, the goal of this paper is to analyze the general problem structure and to develop a technique which requires no iterations and a minimum of simultaneous equation solving. The key to the method is the development of a vector balance equation for each stream mixing point in the flow sheet. The equation for each mixing point is constructed by tracing upstream the input streams to that mixer until either another mixer output or a process input stream is reached and aggregating the stream transformation operators of the flow sheet units encountered along the way. These equations can be constructed very efficieutly from the specification of the flow sheet stream connections using symbolic manipulation. Again, employing only symbolic manipulation, the equations can be sequenced for solution using equation orderin...

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Steady state chemical process simulation

Cited by 88 publications

References 34 publications

A simultaneous‐modular approach to process flowsheeting and optimization. Part I: Theory and implementation

A simultaneous‐modular approach to process flowsheeting and optimization. Part I: Theory and implementation

Exclusive tear sets for flowsheets

Solution of material balances for flowsheets modelled with elementary modules: The unconstrained case

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