A two-fluid nozzle spray dryer atomises liquid feed using compressed air (2–6 bar) mixed with product at the nozzle tip, producing fine droplets of 10–100 µm even at low feed rates (0.1–500 L/h). Processing feeds of 1–10,000 cP with inlet air at 130–250°C, it achieves powder particle size of 5–150 µm and residual moisture below 3% — the preferred configuration for laboratory, pharmaceutical, and small-batch specialty chemical spray drying.
Feed liquid and atomising air (2–6 bar) meet at the nozzle tip, where pneumatic energy shatters the liquid into fine droplets (10–100 µm). Co-current hot air (130–250°C) contacts droplets as they enter the chamber, evaporating moisture within 3–15 seconds. The small droplet size from pneumatic atomisation enables drying of heat-sensitive materials at lower inlet temperatures (130–160°C) with short drying times. Powder collects at the chamber base and cyclone; exhaust passes through a HEPA filter.
Challenges
High Compressed Air Consumption
Pneumatic atomisation requires 2–6 bar continuous air supply; significant operating cost.
Nozzle Clogging with High-Solids Feed
Slurries above 40% solids block nozzle orifice progressively during operation.
Fine Powder Loss Through Cyclone
Sub-5 µm particles pass primary cyclone; secondary filter required for recovery
Narrow Throughput Range per Nozzle Size
Each nozzle orifice optimised for specific flow rate range; multiple nozzles for wide range.
Wall Build-Up at High Feed Viscosity
Partially dried sticky particles adhere to chamber wall at inlet temperature <160°C.
Solutions
- Self-Cleaning Nozzle with Needle Valve: Automated needle plunge clears orifice every 30–60 minutes; prevents clogging.
- Nozzle Array for Scale-Up: Multiple nozzles in parallel maintain droplet size and coverage at higher throughputs.
- Secondary HEPA Bag Filter: Captures sub-5 µm fines from cyclone exhaust; achieves >99.8% powder recovery.
- Heated Nozzle Body (80–120°C): Prevents feed viscosity rise at nozzle tip; maintains consistent atomisation pattern.
- Inlet Air Broom + Chamber Cooling Sweep: Continuous wall sweep airflow keeps chamber walls above dew point; prevents adhesion.
Applications
- Pharmaceutical: Amorphous solid dispersions, inhalation-grade API, micronized drug powder, parenteral excipients.
- Biotechnology: Protein and enzyme powder, vaccine intermediates, probiotic and lyophilisation-alternative drying.
- Food & Beverage: Flavour encapsulation, plant extract drying, specialty ingredient microencapsulation.
- Chemical: Catalyst powder, ceramic microspheres, specialty polymer particle, pigment drying.
- Nutraceuticals: Phytochemical extract drying, omega-3 microencapsulation, antioxidant powder production.
Models & Capacities
| 6B — Two-Fluid Nozzle Spray Dryer (SD-N) — 0.5 kg/h Lab to 1,000 kg/h Large Production — Atomising Air 1.5–6 bar — Droplet 10–100 µm — Powder 5–150 µm | |||||||||
| Model | Scale | Evap. Capacity [kg/h] | Feed Rate [L/h] | Inlet Air Temp [°C] | Outlet Air Temp [°C] | Atomising Air [bar] | Droplet Size [µm] | Powder Size [µm] | |
| SD-N-LAB-0.5 | Lab | 0.5 – 1.5 | 0.1 – 2 | 130 – 220 | 45 – 85 | 1.5 – 4 | 10 – 60 | 5 – 100 | |
| SD-N-LAB-3 | Lab/Pilot | 3 – 8 | 2 – 12 | 140 – 230 | 50 – 85 | 2 – 5 | 10 – 80 | 5 – 120 | |
| SD-N-PIL-20 | Pilot | 20 – 40 | 30 – 60 | 150 – 240 | 55 – 90 | 2 – 6 | 15 – 90 | 8 – 130 | |
| SD-N-50 | Production | 50 – 100 | 70 – 150 | 160 – 250 | 55 – 90 | 3 – 6 | 20 – 100 | 10 – 150 | |
| SD-N-200 | Production | 200 – 400 | 280 – 580 | 170 – 250 | 60 – 90 | 3 – 6 | 25 – 100 | 12 – 150 | |
| SD-N-500 | Large Prod | 500 – 1,000 | 700 – 1,500 | 180 – 250 | 60 – 90 | 4 – 6 | 30 – 100 | 15 – 150 | |