Decentralized control of a kinetically controlled ideal reactive distillation column

Kumar, M. V. Pavan; Kaistha, Nitin

doi:10.1016/j.ces.2007.09.029

Cited by 22 publications

(8 citation statements)

References 40 publications

(55 reference statements)

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“…In 1 mol %. Kumar and Kaistha [22] note that these deviations are due to the column design being kinetically limited (insufficient catalyst hold-up). Stoichiometric feed balancing is an important regulatory objective so that the final steady-state imbalance for the disturbance tested is a possible indicator of the inherent controllability of the design.…”

Section: Dynamic Results For Temperature Inferential Control Structuresmentioning

confidence: 98%

“…It is noted that even as three-point temperature inferential control [22] is possible with, e.g., reflux rate controlling a rectifying tray temperature, two-point temperature control is preferable as it is simpler and allows for tighter control of the two controlled tray temperatures due to lower multivariable interaction with fewer interacting temperature loops (two loops) compared to three-point temperature control (three loops). The low rectifying tray temperature sensitivities with respect to F B and F A also seem to suggest attempting to control a third temperature in the rectifying section is likely to lead to overcontrol.…”

Section: Temperature Inferential Control Structure Synthesismentioning

confidence: 98%

“…The column operates in the kinetically controlled regime [22,26] where the catalyst holdup on the reactive trays is not large enough for reaction equilibrium to be attained on the trays. If the catalyst loading is increased to an extent where reaction equilibrium is attained on the trays, then for a given reactive zone temperature, the composition of the vapor and liquid streams leaving the reactive zone would remain constant, regardless of throughput.…”

Section: Increased Catalyst Loading Per Traymentioning

confidence: 99%

“…These are the prime reasons why the control of RD has attracted great attention in the industry and academia during the last two decades. Several control schemes ranging from decentralized [18][19][20][21][22] to nonlinear control schemes [23][24][25] have been proposed and tested for their closed-loop disturbance rejection characteristics.…”

Section: Introductionmentioning

confidence: 99%

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Control of Quaternary Ideal Endothermic Reactive Distillation with and without Internal Heat Integration

2016

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Decentralized control system design is evaluated for a basic and an internally heat-integrated generic, ideal, double-feed, two-product reactive distillation system. The internally heat-integrated reactive distillation column (HiRDC) is obtained via catalyst redistribution into the rectifying zone and feed tray relocation. For basic regulatory control, three two-point control structures with a fixed reflux rate or a fixed reflux ratio operation policy are synthesized and evaluated for their closed-loop disturbance rejection characteristics using rigorous dynamic simulations. To eliminate the purity offsets for on-target product purities, product purity composition controllers manipulating the reflux ratio and stripping tray temperature set point are implemented. Reactive tray section composition control is necessary for on-target product purity operation of HiRDC.

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Section: Dynamic Results For Temperature Inferential Control Structuresmentioning

confidence: 98%

Section: Temperature Inferential Control Structure Synthesismentioning

confidence: 98%

Section: Increased Catalyst Loading Per Traymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Control of Quaternary Ideal Endothermic Reactive Distillation with and without Internal Heat Integration

2016

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“…Although there have been several estimation and control studies reported for reactive distillation systems, most of the studies are confined to continuous systems (Sneesby et al; Kumar and Daoutidis; Kumar and Kaistha; Engell and Fernholz; Al-Arfaj and Luyben). While batch processes have been receiving more interest in recent years for the production of low-volume, high-value specialty chemicals (Macchietto and Wiederkehr), for estimation and control, batch processes differ considerably from continuous processes especially with reference to the inherent time-varying nature of all states, limited time operation, final time information being more important, etc.…”

Section: Introductionmentioning

confidence: 99%

Robust Trajectory Tracking in a Reactive Batch Distillation Process using Multirate Nonlinear Internal Model Control

Reddy

Patwardhan

Rani

2019

Ind. Eng. Chem. Res.

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Operating a reactive batch distillation (RBD) process in an optimal manner is of paramount importance for improving product quality and profitability in the face of changing market conditions. However, implementation of an open loop optimal control policy may lead to significant reduction in yield and amount of desired product produced when unmeasured disturbances occur during operation. In this work, an observer error feedback-based multirate nonlinear internal model control (NIMC) scheme is developed for optimal trajectory tracking in the face of unmeasured disturbances. In particular, mismatch in the initial conditions and process parameter variations that can occur during RBD operation are considered. To reduce the time required for online computations, a recently proposed reduced order RBD model [Reddy et al. Compt. Chem. Eng., 2017, 106, 40−56] is used for the controller synthesis. Because the thermodynamic model associated with the RBD process has discontinuities, a multirate version of unscented Kalman filter (UKF) has been developed on the basis of the reduced order model for solving the state estimation problem associated with the proposed NIMC formulation. The efficacy of the proposed approach has been demonstrated by simulating an optimal trajectory tracking problem in the RBD process involving production of butyl acetate. The proposed multirate NIMC formulation is found to be computationally efficient and work reasonably well when tested on the RBD process for solving the set point tracking problem in the presence of unmeasured disturbances. In particular, it is advantageous to operate the RBD process using the proposed UKF-NIMC scheme when the system is subjected to unmeasured disturbances.

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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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Decentralized control of a kinetically controlled ideal reactive distillation column

Cited by 22 publications

References 40 publications

Control of Quaternary Ideal Endothermic Reactive Distillation with and without Internal Heat Integration

Control of Quaternary Ideal Endothermic Reactive Distillation with and without Internal Heat Integration

Robust Trajectory Tracking in a Reactive Batch Distillation Process using Multirate Nonlinear Internal Model Control

An overview on controllability analysis of chemical processes

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