Essentials of Fluidization Technology

John R. Grace, Xiaotao Bi, Naoko Ellis, John R. Grace, Xiaotao Bi, Naoko Ellis

• Publisher: Wiley-VCH
• Year: 2020
• Print ISBN: 9783527340644
• eBook ISBN: 9783527699490
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Chemical & Biochemical Engineering
• Index: Technology & Engineering

A concise and clear treatment of the fundamentals of fluidization, with a view to its applications in the process and energy industries.

1
Introduction, History, and Applications

John R. Grace

University of British Columbia, Department of Chemical and Biological Engineering, 2360 East Mall, Vancouver, Canada V6T 1Z3

1.1 Definition and Origins

Fluidization occurs when solid particles are supported and allowed to move relative to each other as a result of vertical motion of a fluid (gas or liquid) in a defined and contained volume. Most commonly, the fluid is a gas blown upwards by a blower or compressor through a perforated flat plate or a series of orifices, but many other configurations are possible. Once an assembly (“bed”) of particles has been actuated in this manner, it is said to be a “fluidized bed.”

The origin of fluidized beds is unclear, but liquid-fluidized beds likely preceded gas-fluidized beds. For example, early fluidization has been attributed to Agricola [1] when he described and illustrated hand jigging for ore dressing. The first industrial applications of fluidized beds were likely beds of ore particles fluidized by liquids in order to classify them by size or density in an operation known as “teetering” [2].

The first widespread application of gas-fluidized beds was in the 1920s in Germany when Winkler [3] patented a novel gasifier. However, the terms “fluidization” and “fluid bed” did not emerge until about 1940 when researchers in the United States developed gas-supported beds for catalytic cracking of heavy hydrocarbons [4, 5]. A plaque commemorating the development of the fluid bed reactor at a local oil refinery was erected at the Louisiana Art and Science Museum in Baton Rouge in 1998.

The term “circulating fluidized bed” (or “CFB”) has been used since the 1980s to cover configurations where there is no upper bed surface, with particles supported by fluid contained in equipment that incorporates one or more gas–solid separator (usually cyclones), as well as recirculation piping as an integral part of the system. These have become popular, mostly for calcination, energy, and metallurgical operations [6].

Commercial fluidized bed reactors are now among the largest chemical reactors in the world. For example, in China fluidized bed combustors have reached a power capacity of 660 MW_e [7].

1.2 Terminology

As in other fields, specialized terminology is used by the fluidization community. Definitions of the following terms may be helpful for those new to the field:

• Agglomeration: Particles sticking together to form assemblies (agglomerates).
• Attrition: Break-up of particles due to collisions or other interactions and stresses.
• Bed expansion: Height of operating fluidized bed divided by static bed height or bed height at minimum fluidization.
• Bubbles: Voids containing few, if any, particles, rising relative to the particles above them and behaving in a somewhat analogous manner to bubbles in liquids.
• Choking: Collapse of dilute gas–solid suspension into dense phase flow when decreasing the gas velocity at constant solids flow. Fo...

Table of contents

• Cover
• Table of Contents
• Preface
• Acknowledgement
• 1 Introduction, History, and Applications
• 2 Properties, Minimum Fluidization, and Geldart Groups
• 3 Liquid Fluidization
• 4 Gas Fluidization Flow Regimes
• 5 Experimental Investigation of Fluidized Bed Systems
• 6 Computational Fluid Dynamics and Its Application to Fluidization
• 7 Hydrodynamics of Bubbling Fluidization
• 8 Slug Flow
• 9 Turbulent Fluidization
• 10 Entrainment from Bubbling and Turbulent Beds
• 11 Standpipes and Return Systems, Separation Devices, and Feeders
• 12 Circulating Fluidized Beds
• 13 Operating Challenges
• 14 Heat and Mass Transfer
• 15 Catalytic Fluidized Bed Reactors
• 16 Fluidized Beds for Gas–Solid Reactions⋆
• 17 Scale-Up of Fluidized Beds
• 18 Baffles and Aids to Fluidization
• 19 Jets in Fluidized Beds
• 20 Downer Reactors
• 21 Spouted (and Spout-Fluid) Beds
• 22 Three-Phase (Gas–Liquid–Solid) Fluidization
• Index
• End User License Agreement