Dynamic Modeling of a Reactive Distillation Column


Book Description

This research focuses on white box modeling of the dynamics of a reactive distillation column, precisely, one that is used for the commercial production of MTBE (methyl-tert-butyl-ether) by the reaction between methanol and isobutylene. The motivation for this study is mainly the process complexity posed by simultaneous reaction and separation which complicates the design and control of the column. In this study, an equilibrium model of reactive distillation column is developed in MATLAB by putting together the MESH equations and other equations like Francis weir formula and reaction rate law. Subsequently, the developed model is validated by comparison of simulation results with industrial data. Finally, the dynamic behaviour of the system is studied by applying step changes to each of the input variables, one at a time. The model of reactive distillation column is successfully developed. It is also proven to be a good representation of the column in the industry because model predictions and plant data come to a good agreement.







Development of Dynamic Models of Reactive Distillation Columns for Simulation and Determination of Control


Book Description

Dynamic models of a reactive distillation column have been developed and implemented in this work. A model describing the steady state behavior of the system has been built in a first step. The results from this steady state model have been compared to data provided from an industrial collaborator and the reconciled model formed the basis for the development of a dynamic model. Four controlled and four manipulated variables have been determined in a subsequent step and step tests for the manipulated variables were simulated. The data generated by the step responses was used for fitting transfer functions between the manipulated and the controlled variables. RGA analysis was performed to find the optimal pairing for controller design. Feedback controllers of PID type were designed between the paired variables found from RGA and the controllers were implemented on the column model. Both servo and regulatory problems have been considered and tested.




Reactive Distillation Design and Control


Book Description

After an overview of the fundamentals, limitations, and scope of reactive distillation, this book uses rigorous models for steady-state design and dynamic analysis of different types of reactive distillation columns and quantitatively compares the economics of reactive distillation columns with conventional multi-unit processes. It goes beyond traditional steady-state design that primarily considers the capital investment and energy costs when analyzing the control structure and the dynamic robustness of disturbances, and discusses how to maximize the economic and environmental benefits of reactive distillation technology.




Reactive Distillation


Book Description

In a reactive distillation column, both the chemical conversion and the distillative separation of the product mixture are carried out simultaneously. Through this integrative strategy, chemical equilibrium limitations can be overcome, higher selectivities can be achieved and heat of reaction can be directly used for distillation. Increased process efficiency and reduction of investments and operational costs are the direct results of this approach. Highly renowned international experts from both industry and academia review the state-of-the-art and the future directions in application, design, analysis and control of Reactive Distillation processes. Part I surveys various industrial applications and covers both established large scale processes as well as new chemical reaction schemes with high future potential. Part II provides the vital details for analysis of reactive phase equilibria, and discusses the importance of chemical reaction kinetics, while Part III focuses on identifying feasible column configurations and designing their internal structure. Analysis and control of the complex dynamic and steady-state behavior of reactive distillation processes are described in Part IV. Reactive Distillation - a very promising alternative to conventional reaction-distillation flow schemes.




Dynamic Modelling and Control of Reactive Distillation for Hydrogenation of Benzene


Book Description

This work presents a modeling and control study of a reactive distillation column used for hydrogenation of benzene. A steady state and a dynamic model have been developed to investigate control structures for the column. The most important aspects of this control problem are that the purity of the product streams regarding benzene need to be met. At the same time as little toluene as possible should be converted. The former is a constraint imposed by EPA regulations while the latter is tied to process economics due to the high octane number of toluene. It is required to satisfy both of these objectives even under the influence of disturbances, as the feed composition changes on a regular basis. The dynamic model is used for developing transfer function models of two potential control structures. Pairing of inputs and outputs is performed based upon the Relative Gain Array (RGA) and PI controllers were designed for each control structure. The controller performance was then compared in simulation studies. From our results, control structure 2 performed better than control structure 1. The main advantage of CS2 over CS1 is noticed in the simulation of feed composition disturbance rejection, where CS2 returns all variables back to steady state within 3 hrs while it take CS1 more than 20 hrs to return the temperature variables back to steady state.










Reactive Distillation Modeling Using Artificial Neural Networks


Book Description

The use of artificial intelligence techniques in the design of processes has generated a line of research of interest, in areas of chemical engineering and especially in the so-called separation processes, in this chapter the combination of artificial neural networks (ANN) is presented and fuzzy dynamic artificial neural networks (DFANN). Applied to the calculation of thermodynamic properties and the design of reactive distillation columns, the ANN and DFANN are mathematical models that resemble the behavior of the human brain, the proposed models do not require linearization of thermodynamic equations, models of mass and energy transfer, this provides an approximate and tight solution compared to robust reactive distillation column design models. Generally, the models must be trained according to a dimensionless model, for the design of a reactive column a dimensionless model is not required, it is observed that the use of robust models for the design and calculation of thermodynamic properties give results that provide better results than those calculated with a commercial simulator such as Aspen Plus (R), it is worth mentioning that in this chapter only the application of neural network models is shown, not all the simulation and implementation are presented, mainly because it is a specialized area where not only requires a chapter for its explanation, it is shown that with a neural network of 16 inputs, 2 hidden layers and 16 outputs, it generates a robust calculation system compared to robust thermodynamic models that contain the same commercial simulator, a characteristic of the network presented is the minimization of overlearning in which the network by its very nature is low. In addition, it is shown that it is a dynamic model that presents adjustment as a function of time with an approximation of 96,Äì98% of adjustment for commercial simulator models such as Aspen Plus (R), the DFANN is a viable alternative for implementation in processes of separation, but one of the disadvantages of the implementation of these techniques is the experience of the programmer both in the area of artificial intelligence and in separation processes.




Distillation


Book Description

The purpose of this book is to offer readers important topics on the modeling, simulation, and optimization of distillation processes. The book is divided into four main sections: the first section is introduction to the topic, the second presents work related to distillation process modeling, the third deals with the modeling of phase equilibrium, one of the most important steps of distillation process modeling, and the the fourth looks at the reactive distillation process, a process that has been applied successfully to a number of applications and has been revealed as a promising strategy for a number of recent challenges.