Sébastien Elgue

Dynamic models for start-up operations of batch distillation columns with experimental validation

The simulation of batch distillation columns during start-up operations is a very challenging modelling problem because of the complex dynamic behaviour. Only few rigorous models for distillation columns start-up are available in literature and generally required a lot of parameters related to tray or pack geometry. On an industrial viewpoint, such a complexity penalizes the achievement of a fast and reliable estimate of start-up periods. In this paper, two “simple” mathematical models are proposed for the simulation of the dynamic behaviour during start-up operations from an empty cold state. These mathematical models are based on a rigorous tray-by-tray description of the column described by conservation laws, liquid–vapour equilibrium relationships and equations representative of hydrodynamics. The models calibration and validation are studied through experiments carried out on a batch distillation pilot plant, with perforated trays, supplied by a water methanol mixture. The proposed models are shown by comparison between simulation and experimental studies to provide accurate and reliable representations of the dynamic behaviour of batch distillation column start-ups, in spite of the few parameters entailed.

Influence of solvent choice on the optimisation of a reaction–separation operation : application to a Beckmann rearrangement reaction

In pharmaceutical syntheses, the solvent choice generally represents a complex design step. Traditionally, this choice is operated according to criteria connected with the reaction step and without any consideration on the following separation steps. The purpose of this study is to highlight the benefits of a global approach of optimisation for the solvent determination. In this way, an optimisation framework dedicated to global synthesis is applied to a simple reaction–separation operation integrating a Beckmann rearrangement reaction, leading to interesting solvent choices.

Intensification of Ester Production in a Continuous Reactor

Numerous continuous intensified reactors are now accessible on the market that offer enhanced thermal performances in a continuous reactor. Such reactors are then particularly suited to fast and highly exothermic reactions. In this paper, the ability to also manage a slow and equilibrated system, the methyl acetate esterification reaction, on condition of intensification in terms of design and operating conditions is presented. To achieve this purpose, a new kinetics model has been developed and validated from experiments carried out in a lab scale batch reactor. Implemented in a simulation framework, this model leads to an intensified design of the reactor and the associated operating conditions. All this intensification methodology has been supported and validated by experimental studies.

From Chemical Process Diagnosis to Cancer Prognosis: An Integrated Approach for Diagnosis and Sensor/Marker Selection

Abstract Classification techniques have shown recently their usefulness for complex process diagnosis. Besides the fact that no physical model for the process is required, they enable to study the problem of sensor location. Preliminary studies made previously in the domain of chemical process diagnosis have been the initial key point to extend its application to the medical diagnosis framework. Despite the behavioral difference, both domains exhibit many common practices. However, medical diagnosis recently has brought serious challenges such as high dimensionality (gene expression profiling) and heterogeneity of data (symbolic histo-pathological factors). We show here that both challenges can be overcome and used in return to improve complex process diagnosis.

Optimisation of global pharmaceutical syntheses integrating environmental aspects

Publisher Summary Pharmaceutical synthesis optimization, because of its complexity, is often reduced to the optimization of the reaction step. This chapter discusses the dynamic model, allowing simulating the different synthesis steps and, particularly start-up and shut-down phases involved. This model connected to an optimization method is able to provide the optimal operating conditions satisfying a global objective. The application to an industrial process highlights the benefits of the proposed methodology. The chapter describes the operating conditions involving the optimization of the global synthesis, satisfying economical and environmental criteria, to develop sustainable methodologies. For this purpose, a framework based on a simulation program, modeling a global synthesis (reaction and separation steps), has been developed. Besides global synthesis treatment, the main features of this work lie in the modeling of batch units and of dynamics, particularly during the start-up and the shut-down involved in the different step.

Measurement-based Run-to-run Optimization of a Batch Reaction-distillation System

Recently, measurement-based optimization schemes have been developed to deal with uncertainty and process variations. One of the methods therein, labeled NCO tracking, relies on appropriate parameterization of the input profiles and adjusts the corresponding input parameters using measurements so as to satisfy the necessary conditions of optimality (NCO). The applicability of NCO-tracking schemes has been demonstrated on several academic-size examples. The goal of this paper is to show that it can be applied with similar ease to more complex real-life systems. A batch reaction-separation system for the production of propylene glycol is used for illustration. A simple parameterization of the optimal solution with four input parameters is derived and only the active terminal constraints are tracked in a run-to-run manner. With this strategy, near optimality is achieved within a few batches.

Pre-Design of a Continuous Intensified Reactor Based on Pure Thermo-Chemical Optimisation

A continuous intensified reactor requires precise information to adapt the design to the reaction to be implemented. In this article we present a two step approach to pre-designing such devices. The first step consists of the optimisation of the operating conditions based only on stoichio-chemical schemes and kinetic laws. This is carried out by adjusting the temperature profile and feeding rate strategy in a batch or pseudo-batch operation. The second step departs from the ideal thermo-kinetic path by taking into account heat removal and reagent injection. A simulator is used to evaluate the impact of these constraints on the selectivity and productivity. The approach is applied to the linear alkylbenzene sulfonation which characteristics present most of the challenges encountered in the intensification. Final results give a pre-design in terms of reactor characteristics (size, injections positions) and operating conditions.

A global approach for the optimisation of batch reaction-separation processes

Abstract Optimisation of fine chemistry syntheses is often restricted to a dissociated approach of the process, lying in the separated determination of optimal conditions of each operating step. In this paper, a global approach of syntheses optimisation is presented. Focusing on the propylene glycol synthesis, this study highlights the benefits and the limits of the proposed methodology compared with a classical one.