Notes on Chemical Process Intensification Lecture

Introduction

• Overview of Chemical Process Intensification (CPI)
• Focus on intensification by fluid flow processes
• Previous lecture covered strategic aspects of CPI

Multiphase Flow Systems

• Definition: Systems where materials exist in different states or phases (gas, liquid, solid).
• Characteristics:
  • One phase is continuous, others are dispersed.
  • Continuous phase can be gas or liquid.
• Types of Multiphase Systems:
  • Two-phase systems: Gas-liquid, liquid-solid, gas-solid.
  • Three-phase systems: Gas-liquid-solid.
  • Four-phase systems: E.g., freeze desalination with butane and saline water.

Applications of Multiphase Flow Systems

Gas-Liquid Systems

• Applications include:
  • Absorption processes (removal of pollutants)
  • Gas-liquid chromatography
  • Industrial gas reactions (e.g., oxygenation, hydrogenation)

Liquid-Gas Systems

• Applications include:
  • Liquid spraying in gas for absorption
  • Production of superphosphate in fertilizers
  • Spray towers for odour removal

Gas-Solid Systems

• Important for:
  • Physical processes (e.g., drying, fluidization)
  • Reactive processes (e.g., combustion, roasting)
  • Power generation (e.g., burning coal)

Liquid-Liquid Systems

• Applications include:
  • Emulsification in pipelines
  • Liquid-liquid extraction for wastewater treatment

Liquid-Solid Systems

• Hydraulic conveying of solids and crystallization processes.

Three-Phase Systems

• Important processes include mineral flotation and fluid bed catalytic cracking.

Process Intensification Mechanisms

Flow-based Process Units

1. Trickle Bed Reactor: Liquid phase flows as laminar stream.
2. Bubble Column Reactor: Increases interfacial area for absorption.
3. Fluidized Bed Reactor: Enhances heat and mass transfer.
4. Rotating Packed Bed: Maximizes contact of phases.
5. Spinning Disk Reactor: Promotes mass transfer through thin liquid films.
6. Multiphase Monolith Reactor: Increases reaction efficiency through structured catalysts.

Advanced Techniques for Process Intensification

• Micro-engineered reactors: Enhance performance through small reaction volumes.
• Reactive separations: Combine reaction and separation in one unit (examples include reactive distillation, absorption).
• Ultrasound processes: Enhance interfacial area and mass transfer via cavitation.

Reactive Distillation

• Combines reaction and distillation in one column.
• Applications include esterification and nitrate reactions.
• Benefits include higher efficiency, reduced equipment costs, and minimized environmental impact.

Reactive Absorption

• Simultaneous absorption and reaction processes.
• Applications in removing pollutants (e.g., CO2, SO2).
• Uses various column types for enhanced mass transfer.

Reactive Extraction

• Involves reaction and extraction, often utilizing liquid ion exchangers.
• Important for processes like biodiesel production.

Conclusion

• Importance of understanding process intensification mechanisms in chemical engineering.
• Suggested further reading for deeper insights.