Fluidized‐Bed Reactors

Abstract The article contains sections titled: 1. Introduction 1.1. The Fluidization Principle 1.2. Forms of Fluidized Beds 1.3. Advantages and Disadvantages of the Fluidized‐Bed Reactor 2. Fluid‐Mechanical Principles 2.1. Minimum Fluidization Velocity 2.2. Expansion of Liquid–Solid Fluidized Beds 2.3. Fluidization Properties of Typical Bed Solids 2.4. State Diagram of Fluidized Bed 2.5. Gas Distribution 2.6. Gas Jets in Fluidized Beds 2.7. Bubble Development 2.8. Elutriation 2.9. Circulating Fluidized Beds 2.9.1. Hydrodynamic Principles 2.9.2. Local Flow Structure in Circulating Fluidized Beds 2.9.3. Design of Solids Recycle System 2.10. Cocurrent Downflow Circulating Fluidized Beds (Downers) 2.11. Attrition of Solids 3. Solids Mixing in Fluidized‐Bed Reactors 3.1. Mechanisms of Solids Mixing 3.2. Vertical Mixing of Solids 3.3. Horizontal Mixing of Solids 3.4. Solids Residence‐Time Properties 3.5. Solids Mixing in Circulating Fluidized Beds 4. Gas Mixing in Fluidized‐Bed Reactors 4.1. Gas Mixing in Bubbling Fluidized Beds 4.2. Gas Mixing in Circulating Fluidized Beds 5. Heat and Mass Transfer in Fluidized‐Bed Reactors 6. Gas–Solid Separation 7. Injection of Liquid Reactants into Fluidized Beds 8. Industrial Applications 8.1. Heterogeneous Catalytic Gas‐Phase Reactions 8.2. Polymerization of Olefins 8.3. Homogeneous Gas‐Phase Reactions 8.4. Gas–Solid Reactions 8.5. Applications in Biotechnology 9. Modeling of Fluidized‐Bed Reactors 9.1. Modeling of Liquid–Solid Fluidized‐Bed Reactors 9.2. Modeling of Gas–Solid Fluidized‐Bed Reactors 9.2.1. Bubbling Fluidized‐Bed Reactors 9.2.2. Circulating Fluidized‐Bed Reactors 9.3. Newer Developments in Modeling Fluidized‐Bed Reactors 9.3.1 Computational Fluid Dynamics 9.3.2 Modeling of Fluidized‐Bed Systems 10. Scale‐up The article gives an overview on fundamentals and applications of fluidized‐bed technology. Some basic fluid‐mechanical principles—minimum fluidization velocity, status diagram, gas distribution, bubble development, and solids entrainment and elutriation—are presented at the beginning, followed by a detailed discussion of circulating fluidized beds, downers, and attrition effects in fluidized‐bed systems. Sections on solids mixing, gas mixing, and heat and mass transfer in fluidized beds complete the fundamentals section, which is followed by an overview on industrial applications. Fluidized‐bed processes for heterogeneous catalytic gas‐phase reactions, for the polymerization of olefins, for homogenous gas‐phase reactions, gas–solid reactions and applications in biotechnology are described in detail. A final chapter is devoted to the modeling of fluidized‐bed reactors.