1. Introduction
In industrial salt production, wet sodium chloride (NaCl) coming from centrifuges or crystallizerscontains residual moisture. To obtain a free-flowing product, this salt is dried using a fluidized bed dryer.
TEMA Process designs and manufacturescustom fluid bed dryers and coolers used in mineral, chemical, food, and salt industries. These systems ensure uniform drying, high energy efficiency, and continuous operation.
2. Principle of Fluidisation
Fluidisation occurs when hot air flows upward through a bed of salt particles, suspending them so they behave like a liquid.
When air velocity reaches the minimum fluidization velocity (Umf):
- The salt particles lift and move freely.
- The bed expands and behaves like aboiling fluid.
- Heat and mass transfer increase significantly.
This improves drying efficiency because each particle is constantly exposed to hot air.
3. TEMA Process Fluid Bed Dryer System
A TEMA Process salt dryer typically includes:
- Feed system (from centrifuge or crystallizer)
- Air plenum and perforated air distribution plate
- Fluidized bed drying chamber
- Heating system (steam coils or gas burner)
- Dust collection system (cyclone / bag filter / scrubber)
- Cooling section
- Product discharge
For food-grade salt, all surfaces in contact with the product are typically made from AISI 316L stainless steel, ensuring hygienic operation.
4. Step-by-Step Drying Process
Step 1 — Wet Salt Feeding
Wet NaCl (typically 3–5% moisture) enters theTEMA fluid bed dryer from a centrifuge.
Step 2 — Air Distribution
Hot air is introduced from the bottom through aperforated distributor plate.
This air is heated by:
- Steam coils
or - Direct gas burner.
Step 3 — Fluidization of Salt Particles
When air velocity increases:
- Salt particles lift
- Bed expands
- Particles move and mix intensively
This creates a fluidized bed.
Step 4 — Heat and Mass Transfer
Inside the fluid bed:
- Hot air transfers heat to the salt crystals.
- Surface moisture evaporates.
- Water vapor exits with the exhaust air.
Because particles continuously circulate, drying isuniform and very efficient.
Step 5 — Dust Removal
The exhaust air contains:
- Water vapor
- Fine salt particles
TEMA systems typically include:
- Cyclones
- Bag filters
- Wet scrubbers
to recover salt fines and meet emission standards.
Step 6 — Cooling Section
Many TEMA fluid bed systems integrate drying and cooling in one unit.
After drying:
- Ambient or conditioned air cools the salt
- Prevents product caking
- Stabilizes the product for storage.
Step 7 — Dry Salt Discharge
The final product leaves the dryer with:
- Moisture ≈ 0.05–0.1%
- Free-flowing crystals
- Uniform temperature.
5. Special Features of TEMA Process Fluid Bed Dryers
1. Continuous operation
Suitable for large salt plants.
2. Shaking fluid bed technology
Mechanical vibration improves:
- Particle movement
- Fluidization stability
- Handling of wider particle size distributions.
3. High thermal efficiency
Optimized airflow and optional heat recovery reduce energy consumption.
4. Integrated cooling section
Drying and cooling in one machine.
5. Hygienic design
For food salt:
- Stainless steel construction
- CIP cleaning systems available.
6. Simplified Process Flow (TEMA Salt Dryer)
Crystallizer / Centrifuge
↓
Wet Salt Feed
↓
TEMA Fluid Bed Dryer
(Hot Air Fluidization)
↓
Moisture Evaporation
↓
Cyclone / Bag Filter
↓
Cooling Section
↓
Dry NaCl Product
7. Advantages of Using TEMA Process Fluid Bed Dryers for Salt
- Uniform drying (no hot spots)
- Gentle handling of crystals
- High heat transfer efficiency
- Low energy consumption
- Continuous operation
- Integrated drying and cooling
- Suitable for food and industrial salt
✅ Summary
In a TEMA Process fluid bed dryer, wet NaCl crystals are fluidized by heated air. The fluidized condition allows excellent heat and mass transfer, resulting in rapid and uniform moisture removal. The system integrates drying, dust recovery, and cooling to produce a high-quality, free-flowing salt product.
