Dynamic Flowsheet Simulation Of Solids Processes

This book presents the latest advances in flowsheet simulation of solids processes, focusing on the dynamic behaviour of systems with interconnected solids processing units, but also covering stationary simulation. The book includes the modelling of solids processing units, for example for comminution, sifting and particle formulation and also for reaction systems. Furthermore, it examines new approaches for the description of solids and their property distributions and for the mathematical treatment of flowsheets with multivariate population balances.

In this contribution the novel system for the dynamic flowsheet simulation of solids processes is presented. The system is generally applicable for all types of solids processes without limitation for specific process types. In a distinction to the existing flowsheet simulation systems, which have been mainly developed with a focus on fluid processes, the novel system allows to treat multidimensional distributed parameters properly. To perform dynamic modeling of various industrial plants the library of dynamic units has been developed. These units can be easily added per drag and drop functionality onto the flowsheet and in this way the necessary process structure can be created. To make a simulation of various granulation plants the new dynamic models of fluidized bed spray granulation have been developed and implemented. The fluidized bed spray granulation is widely used in the chemical, pharmaceutical, food and agricultural industries. In the majority of cases the granulation plants have a complex dynamic or even unstable behavior. Therefore, the dynamic simulation is one the of most effective way to understand process transient behavior, to optimize process and to develop different control strategies. However, for the flowsheet simulation primarily empirical or semi-empirical models are used, where material microparameters and specific apparatus properties are poorly considered. To obtain more detailed estimation of process behavior, the multiscale modeling concept of solids processes has been developed. On the basis of the multiscale modeling methodology the novel multiscale simulation environment has been created. This environment consists of several models, which describe the process on different time and length scales, and has been effectively applied to the fluidized bed spray granulation process.

The book presents a series of articles devoted to modeling, simulation, and optimization of processes, mainly chemical. General methods for process modeling and numerical simulation are described with flowsheeting. Population balances are addressed in detail with application to crystal production; energy saving is frequently optimized, including exergy analysis. The coupling between process simulation and computational fluid dynamics is studied for air classification and bubble columns. Pressure swing adsorption, reactive distillation, and nanofiltration are explained in general and applied to particular processes. The synthesis of carbon dots is solved by the design of experiments method. A safety study addresses the consequences of gas explosion.

In this Ph.D. thesis a system of coupled fluidized bed reactors is modelled and simulated dynamically. Chemical Looping Combustion was used as an exemplary process in both the numerical and the experimental part of this work. For the simulation purpose a novel flowsheeting software was used and models for the needed process units developed and integrated into this software. The needed unit models were three interconnected fluidized bed reactors in circulating and bubbling operation conditions, a cyclone for gas-solid separation and loop seals, which ensured solids transport and gas separation between the reactors. Additionally, lab scale experiments on the reactivity of the used solids, oxygen carrier and solid fuels, were conducted and kinetic parameters extracted. All unit models were connected to a process flowsheet and simulated dynamically. The simulation results were compared to experimental data from a 25 kWth pilot plant operated at the university by the author. It could be shown that a detailed and dynamic simulation of the whole process can be carried out over a time period of more than 45 minutes and the experimental results from start-up, steady state operation and shutdown of the plant were predicted accurately.

The European Symposium on Computer Aided Process Engineering (ESCAPE) series presents the latest innovations and achievements of leading professionals from the industrial and academic communities. The ESCAPE series serves as a forum for engineers, scientists, researchers, managers and students to present and discuss progress being made in the area of computer aided process engineering (CAPE). European industries large and small are bringing innovations into our lives, whether in the form of new technologies to address environmental problems, new products to make our homes more comfortable and energy efficient or new therapies to improve the health and well being of European citizens. Moreover, the European Industry needs to undertake research and technological initiatives in response to humanity's "Grand Challenges," described in the declaration of Lund, namely, Global Warming, Tightening Supplies of Energy, Water and Food, Ageing Societies, Public Health, Pandemics and Security. Thus, the Technical Theme of ESCAPE 21 will be "Process Systems Approaches for Addressing Grand Challenges in Energy, Environment, Health, Bioprocessing & Nanotechnologies."

Inspired by the leading authority in the field, the Centre for Process Systems Engineering at Imperial College London, this book includes theoretical developments, algorithms, methodologies and tools in process systems engineering and applications from the chemical, energy, molecular, biomedical and other areas. It spans a whole range of length scales seen in manufacturing industries, from molecular and nanoscale phenomena to enterprise-wide optimization and control. As such, this will appeal to a broad readership, since the topic applies not only to all technical processes but also due to the interdisciplinary expertise required to solve the challenge. The ultimate reference work for years to come.

Fluidized bed dryers are the prime choice when it comes to drying of heat sensitive products, commonly processed in the pharmaceutical and food industry. As many products in these industries are fine and cohesive, mechanical vibration of the dryer is used to enable or improve fluidization. Thus, the goal of this thesis is the development of a fluidized bed drying model that accounts for the influence of mechanical vibration of the dryer, as well as its implementation in an open-source flowsheet simulation framework. Continuously operated fluidized bed dryers under steady-state conditions are the focus of this thesis. The aim during model development and implementation is the broadest possible application range of the model. A custom-built vibrated fluidized bed dryer is designed and constructed for comprehensive investigations of fluidized bed hydrodynamics and drying kinetics. Based on experimental investigations, a semi-empirical model for hydrodynamics of fine and cohesive powders is developed. The new model is combined with established models to allow for the flowsheet simulation of fluidized bed dryers for particles of all Geldart groups. Additionally, the influence of vibration is accounted for. Comprehensive validation experiments are performed for particles of different Geldart groups, different dryer geometries and a variety of process parameters, including mechanical vibration. Comparison of model predictions with experimental data attributes high accuracy of predicted particle and gas properties. Furthermore, sensitivity analyses are conducted to identify potential weaknesses in underlying model assumptions. Hereby, the validity of underlying assumptions is confirmed and potential optimization parameters for different applications are identified. The proposed model is unprecedented in terms of range of process parameters, variety of particle properties and dryer geometries, tested and found valid for.

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