An investigation of powder granulation by experiments and numerical simulation.
Item
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Title
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An investigation of powder granulation by experiments and numerical simulation.
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Identifier
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AAI9908334
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identifier
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9908334
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Creator
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Khan, Mohammed Irfan.
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Contributor
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Adviser: Gabriel I. Tardos
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Date
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1998
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Language
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English
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Publisher
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City University of New York.
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Subject
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Engineering, Chemical | Engineering, Mechanical
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Abstract
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The objective of present work is to develop a model of granulation process, which predicts product properties of from a knowledge of operating conditions. Granulation is essentially a solid-particle agglomeration process. It improves bulk powder properties like density, flowability, solubility etc., and is an extensively used unit operation in chemical, mineral, pharmaceutical and food industries. Our primary aim in this work is to understand the micro-level physics of this process, and arrive at a macro-level model which relies on a minimal number of readily estimable parameters.;We begin in Chapter 1 by reviewing some basic concepts in granulation modelling. We then proceed to develop a simple model which predicts the mean size of agglomerated product. This model attempts to incorporate the influence of important, and also to a large extent hitherto unexplored, effects of agglomerate breakup. Furthermore, we identify the important problem of deformation and breakup of agglomerates in a shearing medium, and analyze this in Chapter 2. There we also develop two new tools of analysis: those of experiments using a fluidized-bed granular-flow Couette device, and a computer simulation of shear flows of solid particles.;The experimental setup is useful in creating an environment in which particles can flow under conditions of approximately constant, and known, shear. We use this experimental setup to analyze the problem of deformation and breakup of wet agglomerates in a shearing medium. Study of this problem provided useful insight into the micro-level agglomerate breakup phenomenon at work during granulation. Subsequently, we also demonstrate the usefulness of this device in carrying out rheometric studies on flowing solid particulate systems.;The computer simulation serves as a good tool of integrating the micro-level forces and providing an accurate macro-level description of solid-particle flow processes. The central philosophy behind the simulation is to model inter-particle interactions, and compute the individual particle trajectories which result from these interactions. We apply this tool to analyze the problem of shear induced deformation and breakup of wet agglomerates, and compare the results with those obtained from experiments.;In Chapter 3 we improve upon the simulation developed in Chapter 2 by directly simulating an idealized wet granulation experiment. In this model we essentially simulate a shear flow of a system of solid particles, some of which are wet, while the rest dry. This simulation model provides for a complete model of granulation process, in which the properties of the agglomerates like their size, shape and density can be inferred from the input parameters of the simulation. Due to the limitations of the present model we are able to relate these properties only in a qualitative sense. An accurate quantitative relation between these input and output properties can be achieved by means of some further work on the simulation model. Practical means of incorporating these improvements are also discussed.
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Type
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dissertation
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Source
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PQT Legacy CUNY.xlsx
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degree
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Ph.D.
