A continuous fluid bed dryer processes wet granule or paste fed continuously at one end of an elongated fluid bed chamber : heated fluidising air (40–90°C) evaporates moisture as material travels the length of the chamber and exits at the discharge end at target LOD. Processing 10–20,000 kg/h continuously with residence times of 5–30 minutes, it integrates directly into ICH Q13 continuous solid dosage manufacturing lines : receiving continuous discharge from a twin-screw wet granulator or continuous RMG and delivering dried granule continuously to a continuous blender and tablet press.
Wet granule from the upstream continuous granulator enters the feed end of the elongated chamber; a perforated distributor plate spans the full chamber length. Heated fluidising air enters upward through the plate, fluidising the moving granule bed. Material advances from feed end to discharge end by gravity and airflow : residence time is controlled by a weir gate height at the discharge end. Multiple independently controlled heating zones along the chamber length allow temperature profiling : high temperature for rapid initial evaporation and lower temperature for final conditioning near discharge. NIR probes at the discharge measure LOD in real time.
Challenges
Residence Time Distribution (RTD) Broadening at High Feed Rate
Short-circuiting of some material across the bed length : RTD widens; LOD distribution broadens.
Non-Uniform Fluidisation Across Chamber Width at Scale
Wide chambers develop velocity gradients across width : dead zones at chamber edges.
Granule Size Segregation Along Chamber Length
Fine granules migrate faster than coarse : PSD varies along chamber length and at discharge.
Start-Up and Shut-Down Non-Steady-State Product Quality
Material in chamber at start-up and flush-out at shut-down is off-specification : must be diverted.
Continuous Filter Bag Cleaning in Moving Product Bed
Bag pulse cleaning during continuous operation disturbs fluidisation at pulse moment.
Solutions
- Stepped Weir Gates Along Chamber Length (Adjustable Bed Height): Adjustable intermediate weirs create staged zones : narrower RTD at same throughput.
- Tapered Air Distributor Plate (Higher Velocity at Edges than Centre): Tapered plate compensates for natural velocity gradient : uniform fluidisation across full width.
- Zigzag Air Classifier at Discharge End (Separates Fine/Coarse Before LOD Check): Classifier at discharge ensures uniform PSD exits before LOD NIR measurement.
- Divert Valve at Discharge + Start-Up/Shut-Down Bypass Vessel: Non-steady-state material diverted to separate vessel : only on-spec product to downstream.
- Staggered Pulse Sequence (Zone 1 Pulses While Zone 2 Continues : Never Simultaneous): Pulse schedule staggers zones : no more than 20% of bag area pulsed at any moment.
Applications
- Pharmaceutical (Continuous Mfg): ICH Q13 continuous solid dosage inline after twin-screw wet granulator, before continuous blender.
- Nutraceuticals: High-throughput supplement granule continuous drying reduced batch cycle time.
- Food & Beverage: Continuous instant food granule drying, seasoning and flavour granule drying on high-speed lines.
- Chemical: Continuous catalyst granule drying, specialty chemical powder continuous drying line.
- Animal Feed: Continuous feed premix granule drying in high-throughput feed manufacturing plants.
Models & Capacities
| Type 3B : Continuous Fluid Bed Dryer: Models & Capacities (* At inlet air temperature 60°C) | ||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Model | Scale | Throughput [kg/h] | Chamber L [mm] | Chamber W [mm] | Heating Zones | Inlet Air [m³/h] | Inlet Temp [°C] | Max Evap. Water* [kg/h] | LOD [%] | Residence Time [min] | Overall L [mm] | Overall H [mm] | Connected Load [kW] | |
| FBD-CT-LAB | Lab/Pilot | 10–50 | 600 | 300 | 2 | 300–1,200 | 40–90 | 3 | <2 | 10–20 | 1,400 | 1,500 | 8 | |
| FBD-CT-PIL | Pilot | 50–200 | 1,000 | 500 | 2 | 800–3,000 | 40–90 | 8 | <2 | 8–20 | 2,200 | 1,800 | 18 | |
| FBD-CT-300 | Production | 100–500 | 1,500 | 750 | 3 | 2,000–6,000 | 40–90 | 18 | <2 | 8–20 | 3,100 | 2,100 | 38 | |
| FBD-CT-800 | Production | 300–1,200 | 2,200 | 1,050 | 3 | 5,000–15,000 | 40–90 | 50 | <2 | 8–20 | 4,500 | 2,500 | 80 | |
| FBD-CT-2000 | Production | 800–3,000 | 3,000 | 1,400 | 4 | 10,000–30,000 | 40–90 | 120 | <2 | 8–25 | 6,000 | 2,900 | 160 | |
| FBD-CT-5000 | Production | 2,000–7,000 | 4,500 | 1,800 | 4 | 20,000–50,000 | 40–90 | 280 | <2 | 10–25 | 8,500 | 3,400 | 320 | |
| FBD-CT-10000 | Large Prod | 5,000–15,000 | 6,000 | 2,400 | 5 | 35,000–80,000 | 40–90 | 520 | <2 | 10–30 | 11,500 | 3,900 | 580 | |
| FBD-CT-20000 | Large Prod | 10,000–30,000 | 8,000 | 3,200 | 6 | 60,000–150,000 | 40–90 | 1,000 | <2 | 12–30 | 15,500 | 4,500 | 1,100 | |