Dip. Ingegneria Meccanica

Cagliari, Italy

Dip. Ingegneria Meccanica

Cagliari, Italy
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Cogoni G.,Dip. Ingegneria Meccanica | Tronci S.,Dip. Ingegneria Meccanica | Mistretta G.,Dip. Ingegneria Meccanica | Baratti R.,Dip. Ingegneria Meccanica | Romagnoli J.A.,LSU
Chemical Engineering Transactions | Year: 2013

A stochastic global formulation for the description of antisolvent mediated crystal growth processes is discussed based on the Fokker-Planck equation (FPE). The obtained global model is used to define an operating map of the crystallization process, where asymptotic iso-mean and iso-variance curves are reported in an antisolvent flowrate - temperature plane. Using the obtained asymptotic operational map, three different CSDs have been predicted and compared, both in asymptotic and then dynamic conditions, using experimental results. Copyright © 2013, AIDIC Servizi S.r.l.


Najera I.,National Autonomous University of Mexico | Alvarez J.,National Autonomous University of Mexico | Baratti R.,Dip Ingegneria Meccanica | Gutierrez C.,National Autonomous University of Mexico
IFAC-PapersOnLine | Year: 2016

The problem of robustly controlling a highly exothermic gas-phase packed-bed tubular reactor on the basis of feed and reactor temperature measurements is addressed. First, advanced nonlinear control yields a detailed model-based output feedback (OF) control design with passivity and observability solvability conditions, sensor location criterion, and simple tuning. Then, the behavior of the advanced controller is recovered with a simplified model-based realization that amounts to an industrial temperature tracking controller with feedforward (FF) dynamic setpoint compensation. The advanced and industrial controllers are formally connected. The approach is illustrated and tested with a representative case example through numerical simulations. © 2016


Porru M.,Dip. Ingegneria Meccanica | Saliu A.,SARLUX S.R.L. | Baratti R.,Dip. Ingegneria Meccanica
Computer Aided Chemical Engineering | Year: 2014

Motivated by the need to reconstruct blends properties and their behavior in industrial distillation columns for control and monitoring purposes, the problem of the C7+ fractions modeling is addressed with substitute mixture of real components. The reliability of the proposed approach (comparable with the employment of hypothetical component as madein commercial simulators)is demonstrated in the context of the steady state simulation of an industrial debutanizer (located at SARLUX refinery, Italy). © 2014 Elsevier B.V.


BARATTI R.,Dip. Ingegneria Meccanica | TRONCI S.,Dip. Ingegneria Meccanica | SCHAUM A.,University of Kiel | ALVAREZ J.,Metropolitan Autonomous University
IFAC-PapersOnLine | Year: 2016

Motivated by problems in process design, monitoring and control, the effect of multiplicative stochastic uncertainty injection on the behavior of nonlinear dynamical system is studied with Fokker Planck theory for two rather simple case examples selected to draw rigorous results with analytic formulae. The effect of noise multiplicativeness on the shape of the stationary state PDF and of the transient one along deterministic, probability diffusion, and escape time scales is characterized. The findings are corroborated and illustrated with numerical simulations. The results provide insight to assist the improvement of numerical Monte Carlo and polynomial chaos methods for stochastic multi-state multi-noise dynamical chemical processes underline by complex nonlinear behavior. © 2016


Porru M.,Dip. Ingegneria Meccanica | Alvarez J.,Metropolitan Autonomous University | Baratti R.,Dip. Ingegneria Meccanica
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2013

The problem of on-line estimating on the basis of temperature measurements the distillate NC4 impurity in an industrial IC4-NC4 splitter is addressed within an adjustable-structure Geometric Estimation approach, yielding: (i) suggestive sensor location guidelines drawn from detectability measures, and (ii) conclusive results obtained from estimator functioning assessment with simulated and experimental data. The resulting estimator performs the estimation task within an admissible error tolerance, and considerably less ODEs than the ones of the standard EKF technique employed in the majority of related previous studies. © IFAC.


Najera I.,Metropolitan Autonomous University | Alvarez J.,Metropolitan Autonomous University | Baratti R.,Dip. Ingegneria Meccanica
IFAC-PapersOnLine | Year: 2015

The problem of regulating the effluent concentration in an open-loop unstable exothermic jacketed reactor is addressed. The coolant temperature must be adjusted according to temperature as well as flow measurements. First, the robust nonlinear feedforward-output feedback stabilizing control problem is addressed with advanced control theory, yielding: (i) solvability conditions with sensor location criterion, and (ii) closed-loop robust stability coupled with simple tuning guidelines. Then, the behavior of the advanced controller is recovered with a PI temperature controller equiped with: (i) antiwindup protection, and (ii) feedforward dynamic setpoint compensation driven by measured (feed temperature and volumetric flow rate) disturbances. The approach is applied to a representative case example through numerical simulations. © 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.


Porru M.,Dip. Ingegneria Meccanica | Baratti R.,Dip. Ingegneria Meccanica | Alvarez J.,Metropolitan Autonomous University
IFAC-PapersOnLine | Year: 2015

The problem of reducing the energy consumption in an industrial multicomponent distillation column is addressed. The column is subjected to step feed and distillate flow rates, the distillate impurity is regulated by adjusting the heat duty with a PI temperature controller, and the objective is to save energy through control upgrade. First, the nonlinear feedforward output-feedback robust advanced control problem is addressed, drawing the control construction and the solvability conditions. Then, the behavior of the advanced controller is recovered using a PI temperature controller with a dynamic feedforward setpoint compensator driven by the three measured flow rate disturbances. The approach is illustrated and tested through numerical simulations with a model calibrated with industrial data, finding that: the distillate impurity mean is maintained, its variability is reduced by 80 %, and the energy consumption is reduced by 15 %. © 2015, IFAC (International Federation of Automatic Control) Hosting by Elsevier Ltd. All rights reserved.


Porru M.,Dip. Ingegneria Meccanica | Baratti R.,Dip. Ingegneria Meccanica | Alvarez J.,Metropolitan Autonomous University
IFAC Proceedings Volumes (IFAC-PapersOnline) | Year: 2014

The problem of regulating the distillate impurity content in a two-feed (paraffin-olefin) industrial multicomponent distillation column (iso-normal butane splitter) by manipulating the heat duty according to olefin-to-total feedflow load disturbance and tray temperature measurements is addressed. First, the detailed model-based nonlinear state-feedback robust control problem is addressed, identifying the solvability conditions and attainable closed-loop behavior. Then, the behavior of this controller is recovered with an output feedback PI temperature controller with dynamic feedforward setpoint compensation and antiwindup protection. The proposed approach is illustrated and tested through numerical simulations with a detailed model calibrated with industrial data, establishing the feasibility of improving the existing control scheme with PI temperature control plus manual setpoint compensation. © IFAC.


Porru M.,Dip. Ingegneria Meccanica | Alvarez J.,Metropolitan Autonomous University | Baratti R.,Dip. Ingegneria Meccanica
Chemical Engineering Transactions | Year: 2013

The problem of on-line estimating on the basis of temperature measurements the distillate NC4 impurity in an industrial IC4/NC4 splitter (operating at Saras refinery at Sarroch in Italy) is addressed. The application of the adjustable model-based Geometric Estimation approach yields a dynamic data processor that adequately performs the estimation task in the light of a prescribed estimation tolerance with a scheme that is considerably simpler than the Extended Kalman Filter (EKF) employed in previous studies. The implementation of the proposed estimator with experimental data shows that distillate NC4 impurity can be inferred with an uncertainty similar to the one of off-line occasional determinations. Copyright © 2013, AIDIC Servizi S.r.l.

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