Multiple steady states in distillation: Effect of VL(L)E inaccuracies

Bekiaris, Nikolaos; Güttinger, Thomas E.; Morari, Manfred

doi:10.1002/aic.690460510

Cited by 20 publications

(15 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…One might ask whether these phenomena are related to the existence of multiple steady states that have been known to occur in other HAD processes. , “Multiple steady states” (MSS) usually refers to the multiplicity of solutions for systems of nonlinear equations used for steady-state simulation, when these solutions belong to the physical domain. This phenomenon is not only a mathematical feature as it has been experimentally demonstrated. − MSS are usually classified in the three following categories: , (1) input multiplicity occurs when multiple input values exist for a given set of outputs, (2) output multiplicity occurs when multiple output values exist for a given set of inputs, and (3) state multiplicity occurs when multiple output values of internal states exist for a given set of inputs and outputs.…”

Section: Scope Of the Papermentioning

confidence: 99%

Analysis and Multiple Steady States of an Industrial Heterogeneous Azeotropic Distillation

Alliet-Gaubert¹,

Gerbaud²,

Joulia³

et al. 2001

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

A study of an industrial multicomponent heterogeneous azeotropic distillation is presented. The process concerns an organic acid dehydration using an immiscible entrainer. First, a validation of the MESH and thermodynamic models through a comparison between pilot-plant experimental reconciled data and simulation results is conducted. A four-component mixture is considered for the simulation. Case studies of the boiler heat duty are automatically generated by an operating path tool. An ∞/∞ analysis is performed for the heterogeneous azeotropic pilot column and an industrial column with a decanter. Because of practical constraints, the pilot and the industrial columns do not have the same reflux policies. This leads the ∞/∞ analysis to predict multiple steady states for the industrial unit but not for the pilot column. However, multiple steady states are found by simulation both for the pilot and for the industrial unit. Multiple steady states are confirmed by simulation and experimental data for the industrial unit. Because of the positive ∞/∞ analysis, they are attributed to the phase equilibrium properties of the quaternary system. For the pilot column, multiple steady states are found by the simulation and linked to experimental observations. The multiplicity is not caused by the phase equilibrium properties; rather, it is attributed to interactions between the material and energy balances. An analysis of the simulation results helps explain the behavior of the industrial unit: the temperature of the sensitive tray gives rise to a peak in heat. This peak is located very close to the industrial temperature set point and is correlated with an impurity content minimum in the main product stream. An impurity minimum is also evidenced by the simulation for the pilot column. This complex behavior can explain observed difficulties in controlling the process at the industrial set point.

show abstract

Section: Scope Of the Papermentioning

confidence: 99%

Analysis and Multiple Steady States of an Industrial Heterogeneous Azeotropic Distillation

Alliet-Gaubert¹,

Gerbaud²,

Joulia³

et al. 2001

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

show abstract

“…On the other hand, a Hopf bifurcation, with the corresponding appearance of a limit cycle, has also been observed in association with a hysteresis curve for a ternary azeotropic column . However, the occurrence of multiple steady states in distillation simulation might depend, in some instances, on the thermodynamic model used. , …”

Section: Introductionmentioning

confidence: 99%

“…22 simulation might depend, in some instances, on the thermodynamic model used. 20,28 Interestingly, Bekiaris et al 21 presented the theoretical possibility of infinitely many steady states for homogeneous azeotropic distillation with a simplified analysis, which considered infinite reflux, infinitely many trays, and constant molar overflow. However, to the best of our knowledge, this degeneracy of steady states has not been observed in distillation or other process systems described by more realistic models.…”

Section: ■ Introductionmentioning

confidence: 99%

Multiple Steady States and Nonsmooth Bifurcations in Dry and Vaporless Distillation Columns

Cavalcanti

Barton

2020

Ind. Eng. Chem. Res.

View full text Add to dashboard Cite

Many process systems, such as distillation columns and other equipment with phase change, exhibit multiple modes of physical behavior that can be described by non-differentiable (i.e., nonsmooth) models. In this paper, we introduce a nonsmooth model for steady-state multistage distillation that can describe columns with dry and/or vaporless stages reliably. The model consists of a system of nonsmooth MESH and specification equations, without inequality or complementarity constraints, that can be directly solved with the semismooth Newton method using automatically computed generalized derivatives. With a modified version of pseudo-arclength continuation, we have been able to observe several novel types of bifurcations in dry and/or vaporless distillation columns. Many of the bifurcations exhibit degenerate behavior with an infinite number of steady states for certain critical input specifications, and occur in general multistage distillation systems regardless of the mixture components or thermodynamic models chosen. We present case studies drawn from the literature and analyze the occurrence and behavior of the bifurcations with respect to several types of column configurations, involving ideal stages, stage efficiencies, pressure gradients, tray heat transfer, multiple feeds, and side products. The associated bifurcation curves are inherently nonsmooth and can be described mathematically by the concept of piecewise-smooth manifolds introduced in this paper.

show abstract

“…The importance of multiplicity of solutions in separation processes relies on the fact that one set of design parameters can yield several operating conditions. A consequence of this situation is that control actions must be taken to regulate the process operation [9]. In process system engineering, it is important to predict all multiple states, within the practical domain of operating variables, to know whether they are desirable, and to understand how the separation scheme and its performance response to changes in the operating conditions.…”

Section: Introductionmentioning

confidence: 99%

On the multiple solutions of the reactive distillation column for production of fuel ethers

Jaime-Leal

Bonilla-Petriciolet

Segovia‐Hernández

et al. 2013

Chemical Engineering and Processing: Process Intensification

View full text Add to dashboard Cite

Multiple steady states in distillation: Effect of VL(L)E inaccuracies

Abstract: Output multiplicities in heterogeneous azeotropic distillation columns were studied.

Cited by 20 publications

References 35 publications

Analysis and Multiple Steady States of an Industrial Heterogeneous Azeotropic Distillation

Analysis and Multiple Steady States of an Industrial Heterogeneous Azeotropic Distillation

Multiple Steady States and Nonsmooth Bifurcations in Dry and Vaporless Distillation Columns

On the multiple solutions of the reactive distillation column for production of fuel ethers

Contact Info

Product

Resources

About