In the control of batch and continuous distillation columns, one of the most
challenging problem is the difficulty in measuring compositions. This problem
can be handled by estimating the compositions from readily available online
temperature measurements using a state observer. The aim of this
study is to design a state observer that estimates the product composition
in a multicomponent batch distillation column (MBDC) from the temperature
measurements and to test this observer using a batch column simulation. To
achieve this, first a model for MBDC is prepared and compared with the data
from literature where a case column is utilized. After checking the validity of
the simulation package, it is used as a fictitious process for the performance
evaluations.
In the second phase of the study, an extended Kalman Filter (EKF) is designed
by utilizing a simplified model of MBDC and it is implemented for performance
investigation on the case column with 8 trays separating the mixture of cyclohexane,
n-heptane and toluene. The simplified model utilized in EKF results
in response, which have some deviation with rigorous model, mainly due to
the simplification of vapor-liquid equilibrium relationship. In the performance
evaluation, the tuning parameters of EKF / the diagonal terms of process noise
covariance matrix and the diagonal terms of measurement model noise covariance
matrix are changed in the range of 50¡ / 1x10¡ / 7 and 0:5¡ / 5x108 and the optimum
values are found as 0:00001 and 5000, respectively. The effect of number of
measurement points is also investigated with a result of number of component
measurements. The effect of measurement period value is also studied and found
that it has a major effect on the performance which has to be determined by the
available computational facilities. The control of the column is done by utilizing
the designed EKF estimator and the estimator is successfully used in controlling
the product purities in MBDC under variable reflux-ratio operation.
| Identifer | oai:union.ndltd.org:METU/oai:etd.lib.metu.edu.tr:http://etd.lib.metu.edu.tr/upload/12605551/index.pdf |
| Date | 01 December 2002 |
| Creators | Yildiz, Ugur |
| Contributors | Ozgen, Canan |
| Publisher | METU |
| Source Sets | Middle East Technical Univ. |
| Language | English |
| Detected Language | English |
| Type | M.S. Thesis |
| Format | text/pdf |
| Rights | To liberate the content for public access |
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