Industrial Processes: Filtration, Drying, Mixing, and More
Liquid Mixing vs. Solid Mixing
Liquid Mixing
- Generally involves liquid-liquid or liquid-gas mixing.
- Depends on flow currents for material transport.
- Requires less power.
- Results in a homogenous liquid phase.
- Well-mixed samples are homogenous.
- Equipment: Liquid agitators.
- Technology is well-understood and simple.
Solid Mixing
- Resembles low-viscosity liquid mixing to some extent.
- Lacks flow currents in heavy masses; mixing occurs differently.
- Requires higher power.
- Product may have identifiable phases.
- Well-mixed samples can vary in composition.
- Equipment: Mixers and blenders.
- Technology is more complex and less understood.
Membrane Filtration
A membrane filter separates particles from solutions or gases using size exclusion, adsorption, or absorption.
Types
- Microfiltration
- Ultrafiltration
- Nanofiltration
- Reverse Osmosis
Applications
- Water treatment
- Biotechnology
- Pharmaceutical industry
- Food and beverage industry
- Air filtration
Advantages
- High efficiency
- Low pressure drop
Disadvantages
- Fouling and clogging
- Limited chemical resistance
Membrane filtration is a more effective pretreatment than conventional methods, requiring less space and chemicals. Its cost-effectiveness is increasing. The filtration mechanism combines physiochemical interactions and sieving effects.
Rotary Drum Dryer
An industrial dryer that dries materials using hot air in a rotating drum.
Types
- Direct Rotary Dryer
- Indirect Rotary Dryer
- Rotary Kiln Dryer
- Flash Rotary Dryer
- Vacuum Rotary Dryer
Principle
Uses hot air and drum rotation for convection and conduction heat transfer.
Construction
- Drum (steel or stainless steel)
- Heating system
- Drive system
- Feed system
- Discharge system
- Air handling system
Working
- Wet material enters.
- Hot air is introduced.
- Drum rotates, tumbling material.
- Water evaporates.
- Dry material exits.
Uses
- Drying fertilizers, minerals, chemicals, pharmaceuticals, and food products.
Advantages
- High capacity, efficient heat transfer, low labor costs, operational flexibility, wide applications.
Disadvantages
- High investment, large space, noise, dust, fire/explosion risk.
Safety Features
- Explosion-proof electrical systems
- Fire suppression systems
Drying
Drying removes moisture or volatiles, creating a solid or semi-solid product. It prevents corrosion, improves product stability, and enhances material properties like flowability.
Filtration
Filtration separates solids from liquids or gases using a porous medium. It’s crucial in water treatment, oil and gas, pharmaceuticals, and food processing.
Corrosion
Corrosion is the gradual deterioration of metals due to air, moisture, or chemical reactions. Types include general, pitting, crevice, galvanic, and fretting corrosion.
Mixing
Mixing creates a uniform mixture from components by dispersing one within another, aiming for homogeneity.
Centrifugation
Centrifugation separates mixture components based on size and density using centrifugal force. It’s vital in biochemistry, molecular biology, medicine, and pharmacy.