3 research outputs found
Model based control of a liquid swelling constrained batch reactor subject to recipe uncertainties
This work presents the application of nonlinear model predictive control (NMPC) to a
simulated industrial batch reactor subject to safety constraint due to reactor level swelling,
which can occur with relatively fast dynamics. Uncertainties in the implementation of recipes
in batch process operation are of significant industrial relevance. The paper describes a novel
control-relevant formulation of the excessive liquid rise problem for a two-phase batch
reactor subject to recipe uncertainties. The control simulations are carried out using a
dedicated NMPC and optimization software toolbox Optcon which implements state of the
art technologies. The open-loop optimal control problem is computed using the multipleshooting
technique and the arising non-linear programming problem is solved using a
sequential quadratic programming (SQP) algorithm tailored for large scale problems, based
on the freeware optimization environment HQP. The fast response of the NMPC controller is
guaranteed by the initial value embedding and real time iteration technologies. It is
concluded that the OptCon implementation allows small sampling times and the controller is
able to maintain safe and optimal operation conditions, with good control performance
despite significant uncertainties in the implementation of the batch recipe
Comparison of external bulk video imaging with focused beam reflectance measurement and ultra-violet visible spectroscopy for metastable zone identification in food and pharmaceutical crystallization processes
The purpose of the paper is twofold: it describes the proof of concept of the newly
introduced bulk video imaging (BVI) method and it presents the comparison with
existing process analytical technologies (PAT) such as focused beam reflectance
measurement (FBRM) and ultra violet/visible (UV/Vis) spectroscopy. While the latter
two sample the system in small volumes closely to the probe, the BVI approach monitors
the entire or large parts of the crystallizer volume. The BVI method is proposed as a
complementary noninvasive PAT tool and it is shown that it is able to detect the
boundaries of the metastable zone with comparable or better performance than the FBRM
and UV/VIS probes
Endoscopy based in-situ bulk video imaging of batch crystallization processes
External bulk video imaging (eBVI) of crystallization processes has proven to be a
promising technique for metastable zone determination. In this contribution the
endoscopy based in-situ bulk video imaging (iBVI) method is introduced. The video data
is processed using the mean gray intensity method and by a digital image processing
technique which aims to detect the first crystals during nucleation. The experiments have
been carried out in a small scale calorimeter CRCv4, during which the compensation
heater and infrared spectroscopy signals were monitored.
It is concluded that monitoring the onset of the apparent nucleation, formation of particles
with detectable size, using the mean gray intensity (MGI) trend delivers similar
performance to the calorimetric and IR spectroscopy signal, whereas the crystal
recognition method is the fastest, allowing to detect nucleation earlier.
The endoscopy based nucleation monitoring technique is proposed as a complementary
tool to existing process analytical technologies (PAT) since it provides an in-situ, lowcost,
robust, probe-based method for metastable zone identification which can be easily
integrated and automated with existing laboratory hardware and software