ABSTRACT A computer aided tool for the dynamic simulation of fluidized bed incineration processes... more ABSTRACT A computer aided tool for the dynamic simulation of fluidized bed incineration processes is developed. SIMAPI (SIMulateur Aquitain de Procédés d'Incinération) is particularly dedicated to the training of operators working on such processes. The main aspects of the model and the user-friendly graphical interface are presented. The tool abilities are illustrated with the shut down procedure of an industrial unit.
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.
ABSTRACT The context of this paper is energy recovery in an incineration plant. A dynamic model f... more ABSTRACT The context of this paper is energy recovery in an incineration plant. A dynamic model for the description of a drum unit is presented. In the first part, the physical system in question is presented. This description is performed by following the cycle of water within the system. The different devices of the network are presented, as well as the control valves and their roles. A complete list of the state variables used to represent the process is given. Secondly, we focus on the mathematical description of this system. Indeed, the set of equations representative of the process is rendered. This is a differential algebraic system composed of 6 ordinary differential equations and 113 algebraic ones. A predictor-corrector method (Gear’s algorithm) is used to solve the system. The results of the model are shown in case of the turning off of the plant, when the turbine needs to be bypassed. Finally, an explanation of the observed yields of the model is given.
Deposition of elemental sulphur in natural gas transmission line systems has been reported on onl... more Deposition of elemental sulphur in natural gas transmission line systems has been reported on only in recent times. The most common location is immediately downstream of a point of significant pressure reduction. A necessary step to eliminate solid sulphur deposition is to understand the deposit mechanism. Two mechanisms appear possible: condensate formation and desublimation of sulphur vapours. To study the plausible paths of solid sulphur formation, we established a thermodynamic model. The constitutive equations are classically the chemical and physical equilibriums, partial mass balances and energy balance. We chose the Peng Robinson equation of state to describe the phase behaviour. Mixing rules are conventional: quadratic for a and linear for b with one binary interaction coefficient. Desublimation seems to be the most plausible mechanism to explain the solid sulphur formation. Pressure reduction implies temperature reduction, which reinforces solid formation. A solution to minimize the solid sulphur deposition seems to be heating the gas stream immediately before pressure reduction.
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.
The study deals with the methyl acetate (MeAc) transesterification with ethanol (EtOH) to produce... more The study deals with the methyl acetate (MeAc) transesterification with ethanol (EtOH) to produce methanol (MeOH) and ethyl acetate (EtAc). A first screening has shown that a reactive pressure swing process would have the best performance regarding this reaction. This study provides insights on this process behaviour and control via the infinite/infinite analysis. The infinite/infinite analysis allows checking the interrelation of the system streams without any column design consideration. Unfeasible regions, low limit values, multiplicity regions, discontinuities, control difficulties, recommendable operation conditions and column profiles combination are predicted and discussed. All this information is useful to establish an early and suitable system design strategy.
Due to increasingly strict environmental constraints, a new class of secondary refrigerants is ne... more Due to increasingly strict environmental constraints, a new class of secondary refrigerants is needed. The use of ice slurries as secondary refrigerants is a very promising technology. In order to design cold distribution plants efficiently, one must know how to predict the thermodynamic properties of the mixtures. Existing models are based on correlations with numerous parameters. The aim of this
The aim of this work is to propose a tool for the design assistance of District Heating Network (... more The aim of this work is to propose a tool for the design assistance of District Heating Network (DHN) at the beginning of an urban project, as well as for an extension of an existing network. Two goals of DHN optimization are handling at the same time: the optimization of the configuration (network layout, choice between the different production technologies, existence or not of such utilities) and the optimization of the design (mass flow rate, temperature, thermal generating capacity to install, area of the heat exchanger-HX-in sub-station...). The optimization objective is to minimize the global cost of the DHN over 30 years. It includes both operating cost (heating and pumping cost) and investment cost (line, trench, heating plant, HX). The formulation of the optimization problem leads to a mixed integer non-linear programming (MINLP) problem. That means the optimization problem has a single nonlinear objective function (the global cost) subject to numerous linear and nonlinear ...
ABSTRACT A computer aided tool for the dynamic simulation of fluidized bed incineration processes... more ABSTRACT A computer aided tool for the dynamic simulation of fluidized bed incineration processes is developed. SIMAPI (SIMulateur Aquitain de Procédés d'Incinération) is particularly dedicated to the training of operators working on such processes. The main aspects of the model and the user-friendly graphical interface are presented. The tool abilities are illustrated with the shut down procedure of an industrial unit.
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.
ABSTRACT The context of this paper is energy recovery in an incineration plant. A dynamic model f... more ABSTRACT The context of this paper is energy recovery in an incineration plant. A dynamic model for the description of a drum unit is presented. In the first part, the physical system in question is presented. This description is performed by following the cycle of water within the system. The different devices of the network are presented, as well as the control valves and their roles. A complete list of the state variables used to represent the process is given. Secondly, we focus on the mathematical description of this system. Indeed, the set of equations representative of the process is rendered. This is a differential algebraic system composed of 6 ordinary differential equations and 113 algebraic ones. A predictor-corrector method (Gear’s algorithm) is used to solve the system. The results of the model are shown in case of the turning off of the plant, when the turbine needs to be bypassed. Finally, an explanation of the observed yields of the model is given.
Deposition of elemental sulphur in natural gas transmission line systems has been reported on onl... more Deposition of elemental sulphur in natural gas transmission line systems has been reported on only in recent times. The most common location is immediately downstream of a point of significant pressure reduction. A necessary step to eliminate solid sulphur deposition is to understand the deposit mechanism. Two mechanisms appear possible: condensate formation and desublimation of sulphur vapours. To study the plausible paths of solid sulphur formation, we established a thermodynamic model. The constitutive equations are classically the chemical and physical equilibriums, partial mass balances and energy balance. We chose the Peng Robinson equation of state to describe the phase behaviour. Mixing rules are conventional: quadratic for a and linear for b with one binary interaction coefficient. Desublimation seems to be the most plausible mechanism to explain the solid sulphur formation. Pressure reduction implies temperature reduction, which reinforces solid formation. A solution to minimize the solid sulphur deposition seems to be heating the gas stream immediately before pressure reduction.
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.
The study deals with the methyl acetate (MeAc) transesterification with ethanol (EtOH) to produce... more The study deals with the methyl acetate (MeAc) transesterification with ethanol (EtOH) to produce methanol (MeOH) and ethyl acetate (EtAc). A first screening has shown that a reactive pressure swing process would have the best performance regarding this reaction. This study provides insights on this process behaviour and control via the infinite/infinite analysis. The infinite/infinite analysis allows checking the interrelation of the system streams without any column design consideration. Unfeasible regions, low limit values, multiplicity regions, discontinuities, control difficulties, recommendable operation conditions and column profiles combination are predicted and discussed. All this information is useful to establish an early and suitable system design strategy.
Due to increasingly strict environmental constraints, a new class of secondary refrigerants is ne... more Due to increasingly strict environmental constraints, a new class of secondary refrigerants is needed. The use of ice slurries as secondary refrigerants is a very promising technology. In order to design cold distribution plants efficiently, one must know how to predict the thermodynamic properties of the mixtures. Existing models are based on correlations with numerous parameters. The aim of this
The aim of this work is to propose a tool for the design assistance of District Heating Network (... more The aim of this work is to propose a tool for the design assistance of District Heating Network (DHN) at the beginning of an urban project, as well as for an extension of an existing network. Two goals of DHN optimization are handling at the same time: the optimization of the configuration (network layout, choice between the different production technologies, existence or not of such utilities) and the optimization of the design (mass flow rate, temperature, thermal generating capacity to install, area of the heat exchanger-HX-in sub-station...). The optimization objective is to minimize the global cost of the DHN over 30 years. It includes both operating cost (heating and pumping cost) and investment cost (line, trench, heating plant, HX). The formulation of the optimization problem leads to a mixed integer non-linear programming (MINLP) problem. That means the optimization problem has a single nonlinear objective function (the global cost) subject to numerous linear and nonlinear ...
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Papers by Reneaume Jean-Michel