Predictive functional control for separation processes by liquid-liquid extraction
Résumé
A separation process by liquid-liquid extraction is a well-known and widespread
industrial technology implemented to quantitatively recover valuable chemical
elements. In the nuclear industry, such processes have been used for decades to
recover uranium and plutonium from spent fuel. The process is non-linear and
time constants vary over a wide range. Former studies on a simplified model
showed linear controllers such as PID were not adapted to regulate these
separation processes. The objective of this study is to propose process
monitoring by using available physical models within the PAREX code and to
validate the feasibility to monitor a separation process by using directly the PAREX
code as a black box. The Predictive Functional Control (PFC) command law
manages to monitor non-linear separation processes by liquid-liquid extraction,
when using an existing physical model implemented in the PAREX code. An online
alignment of the model on process values is necessary to keep the model
sufficiently representative to predict the future behaviour of the process. As a
reference benchmark, the PID control loop is also simulated with the physical
model. The PFC and PID regulations are compared to evaluate the gain of using
physical models implemented in the PAREX code. A simulation tool has been
developed to implement the PID and Predictive Functional Control (PFC)
controllers for separation processes by liquid-liquid extraction. The PFC
command law manages to monitor non-linear separation processes, when
using a physical model connected to the PAREX code. Even if the PID
controller may be locally more efficient, the great strength of the PFC
controller is to enable good performances on wider operating conditions,
with an easier parametrization. The PFC algorithm is a mean to deal with the
process characteristic features, like non-linearity and time constant change. The
PFC controller appears to be a good candidate for experimental tests. A mid-term
objective is to include the state estimator tool in the control loop to consolidate
the controlled variable measurements. These developments may be regarded as
an add-on module in a digital factory concept. Results shown in this article are
only from simulation. For the sake of data confidentiality, studies with the PAREX
code cannot be published and numerical parameters of the process are
normalized. These simulations will be validated during further experimental tests
Domaines
Génie chimiqueOrigine | Fichiers éditeurs autorisés sur une archive ouverte |
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