scholarly journals Comparing Composition Control Structures for Kaibel Distillation Columns

Processes ◽  
2020 ◽  
Vol 8 (2) ◽  
pp. 218 ◽  
Author(s):  
Yang Yuan ◽  
Kejin Huang ◽  
Haisheng Chen ◽  
Xing Qian ◽  
Lijing Zang ◽  
...  
Keyword(s):  
Control Systems ◽  
Distillation Column ◽  
Tight Control ◽  
Distillation Columns ◽  
Control Structures ◽  
Control Loops ◽  
Composition Control ◽  
Equipment Investment ◽  
Quaternary Mixture ◽  
Operation Cost

Although Kaibel distillation columns are superior to conventional distillation sequences owing to smaller equipment investment and operation cost, they display high nonlinearity and this greatly increases the difficulty of achieving their tight control. To overcome this problem, four decentralized composition control structures, i.e., the CSR/QR, CSR/B, CSD/QR, and CSD/B structures, are proposed and compared based on the control of a Kaibel distillation column fractionating a methanol/ethanol/propanol/butanol quaternary mixture. These four composition control structures all include five composition control loops. While the four of them are employed to maintain the purity of the top, upper sidestream, lower sidestream, and bottom products, the remaining one is employed to minimize the energy consumption of the Kaibel distillation column by maintaining the composition of propanol at the first stage of the prefractionator. Dynamic simulation results show the CSR/QR and CSR/B structures can tightly maintain the purity of the controlled products with a small overshoot and short settling time after facing various disturbances in feed conditions, but the CSD/QR and CSD/B structures lead to oscillatory responses (the latter even shows divergent responses under individual disturbances). At the end of the article, some effective guides for developing composition control systems are given.

scholarly journals Integrated Multiscale Latent Variable Regression and Application to Distillation Columns

2013 ◽  
Vol 2013 ◽  
pp. 1-17 ◽  
Author(s):  
Muddu Madakyaru ◽  
Mohamed N. Nounou ◽  
Hazem N. Nounou
Keyword(s):  
Feature Extraction ◽  
Latent Variable ◽  
Prediction Accuracy ◽  
Distillation Column ◽  
Selection Criterion ◽  
Process Data ◽  
Distillation Columns ◽  
Latent Variable Regression ◽  
Multiscale Filtering ◽  
Modeling Algorithm

Proper control of distillation columns requires estimating some key variables that are challenging to measure online (such as compositions), which are usually estimated using inferential models. Commonly used inferential models include latent variable regression (LVR) techniques, such as principal component regression (PCR), partial least squares (PLS), and regularized canonical correlation analysis (RCCA). Unfortunately, measured practical data are usually contaminated with errors, which degrade the prediction abilities of inferential models. Therefore, noisy measurements need to be filtered to enhance the prediction accuracy of these models. Multiscale filtering has been shown to be a powerful feature extraction tool. In this work, the advantages of multiscale filtering are utilized to enhance the prediction accuracy of LVR models by developing an integrated multiscale LVR (IMSLVR) modeling algorithm that integrates modeling and feature extraction. The idea behind the IMSLVR modeling algorithm is to filter the process data at different decomposition levels, model the filtered data from each level, and then select the LVR model that optimizes a model selection criterion. The performance of the developed IMSLVR algorithm is illustrated using three examples, one using synthetic data, one using simulated distillation column data, and one using experimental packed bed distillation column data. All examples clearly demonstrate the effectiveness of the IMSLVR algorithm over the conventional methods.

scholarly journals Worst-Case Analysis of Digital Control Loops with Uncertain Input/Output Timing

10.29007/c4zl ◽  
2019 ◽  
Author(s):  
Maximilian Gaukler ◽  
Peter Ulbrich
Keyword(s):  
Control Systems ◽  
Digital Control ◽  
Worst Case Analysis ◽  
Real Time Systems ◽  
Input Output ◽  
Worst Case ◽  
Control Loops ◽  
Digital Control Systems ◽  
Uncertain Input ◽  
Time Systems

Benchmark Proposal: The implementation of digital control systems in complex multi- core or distributed real-time systems results in non-deterministic input/output timing. Such timing deviations typically lead to degraded performance or even instability, which in turn may jeopardize safety goals. We present the problem of proving worst-case guarantees for given input/output timing bounds as a benchmark for the verification of hybrid dynamical systems.

Design of Multi-Loop Modal Control Systems for Plants Having Complex Eigenvalues

1968 ◽  
Vol 1 (3) ◽  
pp. T61-T68 ◽  
Author(s):  
B. Porter ◽  
J. D. Carter
Keyword(s):  
Control Systems ◽  
Fourth Order ◽  
Design Procedure ◽  
Modal Control ◽  
The Real ◽  
Control Loops ◽  
Complex Eigenvalues ◽  
Oscillatory Response ◽  
Response Modes

In this paper a design procedure is developed which makes it possible to alter both the real and imaginary parts of any number of pairs of conjugate complex plant eigenvalues: this procedure alters one pair of conjugate eigenvalues at a time by the provision of a suitable pair of control loops. In this way, multi-variable linear plants can be designed so as to possess oscillatory response modes having any desired decrement and frequency. The procedure is illustrated by designing control loops for second- and fourth-order plants having matrices with conjugate complex eigenvalues.

Assessment of control structures for binary distillation columns with secondary reflux and vaporization

1985 ◽  
Vol 24 (3) ◽  
pp. 852-858 ◽  
Author(s):  
Kazuyuki Shimizu ◽  
B. R. Holt ◽  
Manfred Morari ◽  
Richard S. H. Mah
Keyword(s):  
Distillation Columns ◽  
Control Structures
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