Xuân Meyer | ENSIACET - Academia.edu (original) (raw)

Papers by Xuân Meyer

Computer Aided Chemical Engineering, 2009

This work deals with the use of a mathematical model to investigate the influence of the nitrogen... more This work deals with the use of a mathematical model to investigate the influence of the nitrogenous source on the pH during alcoholic fermentation in winemaking. The application of the model to fermentation medium whose nitrogen source was made up only of ammoniac confirms the assumption that the assimilation of one mole of ammonia releases one mole of proton in

Biochemical Engineering Journal, 2003

This paper presents a kinetic model for the enzymatic degradation of the starch during mashing fo... more This paper presents a kinetic model for the enzymatic degradation of the starch during mashing for beer production. Based on a new set of experiments, an original reaction scheme for the hydrolysis of starch by α- and β-amylases has been proposed. Here, the kinetics of the reactions involved in this scheme are described: starch gelatinisation, amylase activities and carbohydrate production.

Process Biochemistry, 2010

A new bacterial species, Saccharothrix algeriensis NRRL B-24137, was isolated in 1992 in the Saha... more A new bacterial species, Saccharothrix algeriensis NRRL B-24137, was isolated in 1992 in the Sahara desert. This filamentous bacterium is able to produce dithiolopyrrolones, molecules presenting antibacterial, antifungal, and anticancer properties. In this study, a "reaction engineering" approach was adopted to gain more knowledge on the growth of Sa. algeriensis and its dithiolopyrrolone production on a semisynthetic liquid medium. The objective is to establish a reaction scheme of the bacterium metabolism from extracellular experimental information, relatively easy to obtain. The approach enabled us to show that Sa. algeriensis could grow using several substrates that were sequentially consumed and that substrate limitation may induce a secondary metabolism in antibiotic production. From these qualitative data, a general reaction scheme was extracted consisting of four reactions: growth via amino acids, glucose consumption for maintenance, growth using glucose, and thiolutin production. The stoichiometric coefficients and the reaction extends were identified using a factorial analysis based on the bilinear structure of the component mass balances in a batch reactor. The analysis of the reaction stoichiometry enabled us to draw some conclusions concerning the substrate consumption pathway.

Despite the many advantages of Reactive Distillation (RD) processes (1), - conversion and selecti... more Despite the many advantages of Reactive Distillation (RD) processes (1), - conversion and selectivity improvement, catalyst requirement reduction, heat integration benefits and azeotropes avoidance -, the industrial community hesitates on firmly adopting that multifunctional process, mainly by lack of systematical and universal design tools. In that context, a state of the art on the thermodynamic fundamentals of reactive systems and

Computer Aided Chemical Engineering, 2005

This contribution proposes a Mixed Integer Non Linear Programming (MINLP) formulation for optimal... more This contribution proposes a Mixed Integer Non Linear Programming (MINLP) formulation for optimal design of a catalytic distillation column based on a generic nonequilibrium model (NEQ). The solution strategy for the global optimization combines Simulated Annealing (SA) and Sequential Quadratic Programming (SQP) in order to minimize the objective function. The solution of this MINLP problem yields the optimal values for the temperature, composition and flow rate profiles, tray geometry, column diameter, reflux ratio, reboiler duty, feed tray location, number of trays and catalytic stage location. Hydraulic constraints (entrainment flooding, down-flow flooding, weeping-dumpling) are also considered. For the example, the production of ETBE (Ethyl tert-butyl ether) is presented here.

A model to predict accurately pH evolution during alcoholic fermentation of must by Saccharomyces... more A model to predict accurately pH evolution during alcoholic fermentation of must by Saccharomyces cerevisiae is proposed for the first time. The objective at least is to determine if the pH measurement could be used for predictive control. The inputs of the model are: the temperature, the concentrations in sugars, ethanol, nitrogen compounds, mineral elements (magnesium, calcium, potassium and sodium) and main organic acids (malic acid, citric acid, acetic acid, lactic acid, succinic acid). In order to avoid uncertainties coming from the possible precipitation, we studied this opportunity on a grape must without any tartaric acid, known as forming complexes with potassium and calcium during the fermentation. The model is based on thermodynamic equilibrium of electrolytic compounds in solution. The dissociation constants depend on the temperature and the alcoholic degree of the solution. The average activity coefficients are estimated by the Debbye-Hückel relation. A fictive diacid is introduced in the model to represent the unmeasured residual species. The molality of hydrogen ions and thus the pH are determined by solving a non-linear algebraic equations system consisted of mass balances, chemical equilibrium equations and electroneutrality principle. Simulation results showed a good capacity of the model to represent the pH evolution during fermentation.

Industrial & Engineering Chemistry Research, 2006

ABSTRACT The objective of this contribution is to propose a mixed integer nonlinear programming (... more ABSTRACT The objective of this contribution is to propose a mixed integer nonlinear programming (MINLP) formulation for optimal design of a catalytic distillation column based on a generic nonequilibrium (NEQ) model. The use of this NEQ model presents two main advantages: (i) the computation of tray efficiencies is entirely avoided and (ii) the geometrical parameters of the column's hardware can be optimized. The minimization of the total annualized cost is submitted to three sets of constraints: the model equations, the product specification, and the tray hydraulic equations. The solution strategy for the optimization uses a combination of simulated annealing and sequential quadratic programming. Catalytic distillation of ethyl tert-butyl ether (ETBE) is considered as an illustrative example. The results of the optimization are discussed. Pre- and postoptimal sensitivity analysis is also performed.

Journal of Bioscience and Bioengineering, 2008

Development of bacterial resistance to antibiotics has lead to investigations of rare bacteria, w... more Development of bacterial resistance to antibiotics has lead to investigations of rare bacteria, which produce new bioactive molecules. Saccharothrix algriensis has been isolated from the desert Maghreb. It produces dithiolopyrrolones, some of which were newly identified. In order to optimize and control production of dithiolopyrrolones, investigation regarding microorganism metabolism was required. Growth on semisynthetic medium containing 2 g ⋅l -1 of yeast extract was complicated because it was performed on several substrates. Moreover, because development of this bacterium on minimum medium was difficult, its composition was optimized by screening of different compounds led by yeast extract. Uracil added to the minimum medium allowed a maximum biomass production of 1.35 g ⋅l -1 compared to 0.32 g ⋅l -1 without uracil. Moreover, nonpolar amino acids and trace metal elements stimulated Saccharothrix algeriensis growth.

Chemical Engineering Research & Design, 2007

First steps of the development of a catalytic reactive distillation process for the production of... more First steps of the development of a catalytic reactive distillation process for the production of n-propyl acetate based on experiments and simulations are proposed. The kinetics for homogeneously (sulphuric acid) and heterogeneously (Amberlyst 15) catalysed reaction were investigated and the constants for a pseudo-homogeneous model are presented. Pilot plant experiments were performed using a homogeneous strong acid catalyst in a

Computers & Chemical Engineering, 1999

The modeling of batch crystallization involves a population balance to get the crystal size distr... more The modeling of batch crystallization involves a population balance to get the crystal size distribution which is one of the most important properties in this process. Thus, this model leads to a system of integral, partial differential and algebraic equations (IPDAE). This system can be easily solved by finite difference methods with uniform discretization. However to increase the calculation efficiency and the crystal size distribution accuracy, an adaptive finite difference method with a non-uniform discretization was developed. Results of both methods are compared in term of efficiency and are confronted to experimental data in term of accuracy.

Computers & Chemical Engineering, 2004

A general and polyvalent model for the dynamic simulation of a vapor, liquid, liquid-liquid, vapo... more A general and polyvalent model for the dynamic simulation of a vapor, liquid, liquid-liquid, vapor-liquid or vapor-liquid-liquid stage is proposed. This model is based on the τ -method introduced as a minimization problem by for steady-state simulation. They suggested modifying the mole fraction summation such that the same set of governing equations becomes valid for all phase regions. Thanks to judicious additional switch equations, the τ -formulation is extended to dynamic simulation and the minimization problem is transformed into a set of differential algebraic equations (DAE). Validation of the model consists in testing its capacity to overcome phase number changes and to be able to solve several problems with the same set of equations: calculation of heterogeneous residue curves, azeotropic points and distillation boundaries in ternary diagrams.

Chemical Engineering Science, 2002

The PBE (population balance equation) containing birth, growth, agglomeration and breakage kineti... more The PBE (population balance equation) containing birth, growth, agglomeration and breakage kinetics is described by a conservation law with a moving source term. For the solution of the PBE, we compare two accurate front tracking methods such as a modiÿed method of characteristics (MOC) and a ÿnite di erence method with the weighted essentially non-oscillatory (WENO) scheme. Both methods are applied to a potassium sulfate crystallization problem (K2SO4-H2O system) with a discontinuous initial condition. Parameters of agglomeration and breakage kinetics are estimated on the basis of the experimental data of the K2SO4-H2O system.

Chemical Engineering Research and Design, 2005

A procedure that combines feasibility analysis, synthesis and design of reactive distillation col... more A procedure that combines feasibility analysis, synthesis and design of reactive distillation columns is introduced. The main interest of this methodology lies on a progressive introduction of the process complexity. From minimal information concerning the physicochemical properties of the system, three steps lead to the design of the unit and the specification of its operating conditions. Most of the methodology exploits and enriches approaches found in the literature. Each step is described and our contribution is underlined. Its application is currently limited to equilibrium reactive systems where degree of freedom is equal to 2 or less than 2. This methodology which provides a reliable initialization point for the optimization of the process has been applied with success to different synthesis. The production of methyl-tert-butyl-ether (MTBE) and methyl acetate are presented as examples.

Chemical Engineering and Processing: Process Intensification, 2008

Chemical Engineering and Processing: Process Intensification, 2008

In this contribution, a sequential and hierarchical approach for the feasibility analysis and the... more In this contribution, a sequential and hierarchical approach for the feasibility analysis and the preliminary design of reactive distillation columns is extended to systems involving vapour phase chemical reaction and is successfully applied to the HI vapour phase decomposition to produce H2.

Chemical Engineering and Processing: Process Intensification, 2008

In this paper, the optimal design of process systems generically used in chemical industries is s... more In this paper, the optimal design of process systems generically used in chemical industries is studied. The closely coupled nature of optimal design specification of the equipment, the determination of the optimal process parameters in steady-state, moreover, some issues of the application of optimal control is shown. The solution of the overall optimization problem including (i) optimal design of the equipment and (ii) specification of its optimal control strategy can be found relying on two different design concepts, namely, on the conventionally used sequential or, on the newly emerged simultaneous design approaches. This paper gives the theoretical background of the ideas and presents a comparative summary of the approaches. The two approaches are contrasted to each other in which the effects of the interaction of optimal process design and optimal control is highlighted. A new simultaneous optimization procedure providing economic and operability benefits over the traditional stand-alone approach is proposed. The applicability of the idea is demonstrated by means of a design study carried out for optimal design of a coaxial heat exchanger and a reactive distillation column for the synthesis of ethyl tert butyl ether (ETBE), relying on the benefits of the utilization of optimal control.

Computers & Industrial Engineering, 2014

ABSTRACT Thanks to a wide and dynamic research community on short term production scheduling, a l... more ABSTRACT Thanks to a wide and dynamic research community on short term production scheduling, a large number of modelling options and solving methods have been developed in the recent years both in chemical production and manufacturing domains. This trend is expected to grow in the future as the number of publications is constantly increasing because of industrial interest in the current economic context. The frame of this work is the development of a decision-support system to work out an assignment strategy between scheduling problems, mathematical modelling options and appropriate solving methods. The system must answer the question about which model and which solution method should be applied to solve a new scheduling problem in the most convenient way. The decision-support system is to be built on the foundations of Case Based Reasoning (CBR). CBR is based on a data base which encompasses previously successful experiences. The three major contributions of this paper are: (i) the proposition of an extended and a more exhaustive classification and notation scheme in order to obtain an efficient scheduling case representation (based on previous ones), (ii) a method for bibliographic analysis used to perform a deep study to fill the case base on the one hand, and to examine the topics the more or the less examined in the scheduling domain and their evolution over time on the other hand, and (iii) the proposition of criteria to extract relevant past experiences during the retrieval step of the CBR. The capabilities of our decision support system are illustrated through a case study with typical constraints related to process engineering production in beer industry.

Computer Aided Chemical Engineering, 2009

This work deals with the use of a mathematical model to investigate the influence of the nitrogen... more This work deals with the use of a mathematical model to investigate the influence of the nitrogenous source on the pH during alcoholic fermentation in winemaking. The application of the model to fermentation medium whose nitrogen source was made up only of ammoniac confirms the assumption that the assimilation of one mole of ammonia releases one mole of proton in

Biochemical Engineering Journal, 2003

This paper presents a kinetic model for the enzymatic degradation of the starch during mashing fo... more This paper presents a kinetic model for the enzymatic degradation of the starch during mashing for beer production. Based on a new set of experiments, an original reaction scheme for the hydrolysis of starch by α- and β-amylases has been proposed. Here, the kinetics of the reactions involved in this scheme are described: starch gelatinisation, amylase activities and carbohydrate production.

Process Biochemistry, 2010

A new bacterial species, Saccharothrix algeriensis NRRL B-24137, was isolated in 1992 in the Saha... more A new bacterial species, Saccharothrix algeriensis NRRL B-24137, was isolated in 1992 in the Sahara desert. This filamentous bacterium is able to produce dithiolopyrrolones, molecules presenting antibacterial, antifungal, and anticancer properties. In this study, a "reaction engineering" approach was adopted to gain more knowledge on the growth of Sa. algeriensis and its dithiolopyrrolone production on a semisynthetic liquid medium. The objective is to establish a reaction scheme of the bacterium metabolism from extracellular experimental information, relatively easy to obtain. The approach enabled us to show that Sa. algeriensis could grow using several substrates that were sequentially consumed and that substrate limitation may induce a secondary metabolism in antibiotic production. From these qualitative data, a general reaction scheme was extracted consisting of four reactions: growth via amino acids, glucose consumption for maintenance, growth using glucose, and thiolutin production. The stoichiometric coefficients and the reaction extends were identified using a factorial analysis based on the bilinear structure of the component mass balances in a batch reactor. The analysis of the reaction stoichiometry enabled us to draw some conclusions concerning the substrate consumption pathway.

Despite the many advantages of Reactive Distillation (RD) processes (1), - conversion and selecti... more Despite the many advantages of Reactive Distillation (RD) processes (1), - conversion and selectivity improvement, catalyst requirement reduction, heat integration benefits and azeotropes avoidance -, the industrial community hesitates on firmly adopting that multifunctional process, mainly by lack of systematical and universal design tools. In that context, a state of the art on the thermodynamic fundamentals of reactive systems and

Computer Aided Chemical Engineering, 2005

This contribution proposes a Mixed Integer Non Linear Programming (MINLP) formulation for optimal... more This contribution proposes a Mixed Integer Non Linear Programming (MINLP) formulation for optimal design of a catalytic distillation column based on a generic nonequilibrium model (NEQ). The solution strategy for the global optimization combines Simulated Annealing (SA) and Sequential Quadratic Programming (SQP) in order to minimize the objective function. The solution of this MINLP problem yields the optimal values for the temperature, composition and flow rate profiles, tray geometry, column diameter, reflux ratio, reboiler duty, feed tray location, number of trays and catalytic stage location. Hydraulic constraints (entrainment flooding, down-flow flooding, weeping-dumpling) are also considered. For the example, the production of ETBE (Ethyl tert-butyl ether) is presented here.

A model to predict accurately pH evolution during alcoholic fermentation of must by Saccharomyces... more A model to predict accurately pH evolution during alcoholic fermentation of must by Saccharomyces cerevisiae is proposed for the first time. The objective at least is to determine if the pH measurement could be used for predictive control. The inputs of the model are: the temperature, the concentrations in sugars, ethanol, nitrogen compounds, mineral elements (magnesium, calcium, potassium and sodium) and main organic acids (malic acid, citric acid, acetic acid, lactic acid, succinic acid). In order to avoid uncertainties coming from the possible precipitation, we studied this opportunity on a grape must without any tartaric acid, known as forming complexes with potassium and calcium during the fermentation. The model is based on thermodynamic equilibrium of electrolytic compounds in solution. The dissociation constants depend on the temperature and the alcoholic degree of the solution. The average activity coefficients are estimated by the Debbye-Hückel relation. A fictive diacid is introduced in the model to represent the unmeasured residual species. The molality of hydrogen ions and thus the pH are determined by solving a non-linear algebraic equations system consisted of mass balances, chemical equilibrium equations and electroneutrality principle. Simulation results showed a good capacity of the model to represent the pH evolution during fermentation.

Industrial & Engineering Chemistry Research, 2006

ABSTRACT The objective of this contribution is to propose a mixed integer nonlinear programming (... more ABSTRACT The objective of this contribution is to propose a mixed integer nonlinear programming (MINLP) formulation for optimal design of a catalytic distillation column based on a generic nonequilibrium (NEQ) model. The use of this NEQ model presents two main advantages: (i) the computation of tray efficiencies is entirely avoided and (ii) the geometrical parameters of the column's hardware can be optimized. The minimization of the total annualized cost is submitted to three sets of constraints: the model equations, the product specification, and the tray hydraulic equations. The solution strategy for the optimization uses a combination of simulated annealing and sequential quadratic programming. Catalytic distillation of ethyl tert-butyl ether (ETBE) is considered as an illustrative example. The results of the optimization are discussed. Pre- and postoptimal sensitivity analysis is also performed.

Journal of Bioscience and Bioengineering, 2008

Development of bacterial resistance to antibiotics has lead to investigations of rare bacteria, w... more Development of bacterial resistance to antibiotics has lead to investigations of rare bacteria, which produce new bioactive molecules. Saccharothrix algriensis has been isolated from the desert Maghreb. It produces dithiolopyrrolones, some of which were newly identified. In order to optimize and control production of dithiolopyrrolones, investigation regarding microorganism metabolism was required. Growth on semisynthetic medium containing 2 g ⋅l -1 of yeast extract was complicated because it was performed on several substrates. Moreover, because development of this bacterium on minimum medium was difficult, its composition was optimized by screening of different compounds led by yeast extract. Uracil added to the minimum medium allowed a maximum biomass production of 1.35 g ⋅l -1 compared to 0.32 g ⋅l -1 without uracil. Moreover, nonpolar amino acids and trace metal elements stimulated Saccharothrix algeriensis growth.

Chemical Engineering Research & Design, 2007

First steps of the development of a catalytic reactive distillation process for the production of... more First steps of the development of a catalytic reactive distillation process for the production of n-propyl acetate based on experiments and simulations are proposed. The kinetics for homogeneously (sulphuric acid) and heterogeneously (Amberlyst 15) catalysed reaction were investigated and the constants for a pseudo-homogeneous model are presented. Pilot plant experiments were performed using a homogeneous strong acid catalyst in a

Computers & Chemical Engineering, 1999

The modeling of batch crystallization involves a population balance to get the crystal size distr... more The modeling of batch crystallization involves a population balance to get the crystal size distribution which is one of the most important properties in this process. Thus, this model leads to a system of integral, partial differential and algebraic equations (IPDAE). This system can be easily solved by finite difference methods with uniform discretization. However to increase the calculation efficiency and the crystal size distribution accuracy, an adaptive finite difference method with a non-uniform discretization was developed. Results of both methods are compared in term of efficiency and are confronted to experimental data in term of accuracy.

Computers & Chemical Engineering, 2004

A general and polyvalent model for the dynamic simulation of a vapor, liquid, liquid-liquid, vapo... more A general and polyvalent model for the dynamic simulation of a vapor, liquid, liquid-liquid, vapor-liquid or vapor-liquid-liquid stage is proposed. This model is based on the τ -method introduced as a minimization problem by for steady-state simulation. They suggested modifying the mole fraction summation such that the same set of governing equations becomes valid for all phase regions. Thanks to judicious additional switch equations, the τ -formulation is extended to dynamic simulation and the minimization problem is transformed into a set of differential algebraic equations (DAE). Validation of the model consists in testing its capacity to overcome phase number changes and to be able to solve several problems with the same set of equations: calculation of heterogeneous residue curves, azeotropic points and distillation boundaries in ternary diagrams.

Chemical Engineering Science, 2002

The PBE (population balance equation) containing birth, growth, agglomeration and breakage kineti... more The PBE (population balance equation) containing birth, growth, agglomeration and breakage kinetics is described by a conservation law with a moving source term. For the solution of the PBE, we compare two accurate front tracking methods such as a modiÿed method of characteristics (MOC) and a ÿnite di erence method with the weighted essentially non-oscillatory (WENO) scheme. Both methods are applied to a potassium sulfate crystallization problem (K2SO4-H2O system) with a discontinuous initial condition. Parameters of agglomeration and breakage kinetics are estimated on the basis of the experimental data of the K2SO4-H2O system.

Chemical Engineering Research and Design, 2005

A procedure that combines feasibility analysis, synthesis and design of reactive distillation col... more A procedure that combines feasibility analysis, synthesis and design of reactive distillation columns is introduced. The main interest of this methodology lies on a progressive introduction of the process complexity. From minimal information concerning the physicochemical properties of the system, three steps lead to the design of the unit and the specification of its operating conditions. Most of the methodology exploits and enriches approaches found in the literature. Each step is described and our contribution is underlined. Its application is currently limited to equilibrium reactive systems where degree of freedom is equal to 2 or less than 2. This methodology which provides a reliable initialization point for the optimization of the process has been applied with success to different synthesis. The production of methyl-tert-butyl-ether (MTBE) and methyl acetate are presented as examples.

Chemical Engineering and Processing: Process Intensification, 2008

Chemical Engineering and Processing: Process Intensification, 2008

In this contribution, a sequential and hierarchical approach for the feasibility analysis and the... more In this contribution, a sequential and hierarchical approach for the feasibility analysis and the preliminary design of reactive distillation columns is extended to systems involving vapour phase chemical reaction and is successfully applied to the HI vapour phase decomposition to produce H2.

Chemical Engineering and Processing: Process Intensification, 2008

In this paper, the optimal design of process systems generically used in chemical industries is s... more In this paper, the optimal design of process systems generically used in chemical industries is studied. The closely coupled nature of optimal design specification of the equipment, the determination of the optimal process parameters in steady-state, moreover, some issues of the application of optimal control is shown. The solution of the overall optimization problem including (i) optimal design of the equipment and (ii) specification of its optimal control strategy can be found relying on two different design concepts, namely, on the conventionally used sequential or, on the newly emerged simultaneous design approaches. This paper gives the theoretical background of the ideas and presents a comparative summary of the approaches. The two approaches are contrasted to each other in which the effects of the interaction of optimal process design and optimal control is highlighted. A new simultaneous optimization procedure providing economic and operability benefits over the traditional stand-alone approach is proposed. The applicability of the idea is demonstrated by means of a design study carried out for optimal design of a coaxial heat exchanger and a reactive distillation column for the synthesis of ethyl tert butyl ether (ETBE), relying on the benefits of the utilization of optimal control.

Computers & Industrial Engineering, 2014

ABSTRACT Thanks to a wide and dynamic research community on short term production scheduling, a l... more ABSTRACT Thanks to a wide and dynamic research community on short term production scheduling, a large number of modelling options and solving methods have been developed in the recent years both in chemical production and manufacturing domains. This trend is expected to grow in the future as the number of publications is constantly increasing because of industrial interest in the current economic context. The frame of this work is the development of a decision-support system to work out an assignment strategy between scheduling problems, mathematical modelling options and appropriate solving methods. The system must answer the question about which model and which solution method should be applied to solve a new scheduling problem in the most convenient way. The decision-support system is to be built on the foundations of Case Based Reasoning (CBR). CBR is based on a data base which encompasses previously successful experiences. The three major contributions of this paper are: (i) the proposition of an extended and a more exhaustive classification and notation scheme in order to obtain an efficient scheduling case representation (based on previous ones), (ii) a method for bibliographic analysis used to perform a deep study to fill the case base on the one hand, and to examine the topics the more or the less examined in the scheduling domain and their evolution over time on the other hand, and (iii) the proposition of criteria to extract relevant past experiences during the retrieval step of the CBR. The capabilities of our decision support system are illustrated through a case study with typical constraints related to process engineering production in beer industry.