Dynamically Structured Flow in Pulsed Fluidised Beds (Springer Theses)

✍ Scribed by Kaiqiao Wu

• Publisher: Springer
• Year: 2021
• Tongue: English
• Leaves: 172
• Category: Library

✦ Synopsis

This book analyses the use of a pulsed gas flow to structure bubbling gas-solid fluidised beds and to induce a special fluidisation state, called "dynamically structured flow", as a promising approach to process intensification.

It explores the properties of bubbles rising in staggered periodic arrays without direct interaction, assessing their size, separation, and velocity, and explains how a highly uniform, scalable flow offers tight control over the system hydrodynamics. These features are desirable, as they not only bypass engineering challenges occurring in traditional operations, such as maldistribution and non-uniform contact, but also allow to decouple conflicting design objectives, such as mixing and gas-solid contact. The thesis also presents computational simulations which reveal the periodic transitions of the particulate phase between fluid-like and solid-like behaviour.

This book will be of interest to researchers, engineers, and graduate students alike, particularly those working in industrial drying, combustion, and chemical production.

✦ Table of Contents

Supervisor’s Foreword
Abstract
Acknowledgements
Impact Statement
Contents
1 Introduction
1.1 Granular Flow and Fluidisation
1.2 Challenges to Engineering of Fluidised Beds
1.3 Multi-scale Modelling of Gas-Solid Flows
1.3.1 Discrete Element Model
1.3.2 Two-Fluid Model
1.4 Methods for Structuring Bed Hydrodynamics
1.5 Dynamic Patterns in Shallow Granular Layers
1.5.1 Vibro-Driven Patterns
1.5.2 Modelling of Pattern Formation in Vibrated Layers
1.5.3 Gas-Driven Patterns
1.5.4 Modelling of Pattern Formation in Pulsed Layers
1.6 Origin of Bubble Patterns in Pulsed Fluidised Beds
1.7 Thesis Objectives and Outline
References
2 Bubbling Properties in Pulsed Fluidised Beds
2.1 Introduction
2.2 Experimental Implementation and Analysis Methodology
2.2.1 Design of Quasi-2D Fluidised Bed Setup
2.2.2 Generation of Oscillatory Gas Flow
2.2.3 Gas Distribution
2.2.4 Particle Properties
2.2.5 Image Analysis
2.3 Results and Discussion
2.3.1 Validation of Gas Distribution
2.3.2 Impacts of Pulsed Flow on Bubbling Properties
2.3.3 Influence of Structuring on Flow Properties
2.3.4 Discussion
2.4 Conclusions
References
3 A Structuring Regime to Control Bubbling Beds
3.1 Introduction
3.2 Experimental Implementation and Analysis Methodology
3.2.1 Pattern Intensity
3.2.2 Measurement of Bubble Properties
3.3 Results and Discussion
3.3.1 Impact of Flow Conditions on Pattern Intensity
3.3.2 Impact of Bed Height on Pattern Intensity
3.3.3 Correlation Between Pattern Intensity and Flow Properties
3.3.4 Discussion
3.4 Conclusions
References
4 Modelling Dynamically Structured Fluidisation
4.1 Introduction
4.2 Model Implementation
4.2.1 Governing Equations and Closures of Two-Fluid Model
4.2.2 Governing Equations of Discrete Element Model
4.2.3 Interphase Momentum Exchange
4.2.4 Experimental Implementation
4.2.5 Computational Setup and Numerical Implementation
4.2.6 Analysis Methodology
4.3 Results and Discussion
4.3.1 Experimental and Computational Bed Dynamics
4.3.2 Description of the Bed Dynamics During a Patterned State
4.3.3 Modelling Larger Pulsed Beds Using Two-Fluid Models
4.3.4 Discussion
4.4 Conclusions
References
5 The Role of Solid Mechanics in Stabilising Structured Flows
5.1 Introduction
5.2 Experimental Implementation
5.3 Numerical Implementation
5.4 Bubble Recognition and Analysis
5.5 Results and Discussion
5.5.1 Appearance of Structured Bubble Patterns
5.5.2 Evolution of Single-Array Bubble Patterns
5.5.3 Evolution of Double-Array Bubble Patterns
5.5.4 Flow Behaviour of Frictionless Particles in Pulsed Beds
5.5.5 Flow Behaviour of Frictional Particles in Pulsed Beds
5.5.6 Discussion
5.6 Conclusions
References
6 Conclusions
Appendix A
A.1 Experimental Quasi-2D Fluidised Bed
A.2 Gas Flow Calibration Setup
A.3 Gas Supply Setup
Appendix B
B.1 Regularity of Triangle Tessellation
B.2 Regularity of Bubble Pattern
Appendix C
Notation
References