A rotary atomiser spray dryer uses a high-speed centrifugal disc (10,000–25,000 RPM) to atomise feed liquid into 20–200 µm droplets across a wide range of feed viscosities (1–5,000 cP) and flow rates (10–10,000 L/h). Inlet air temperatures of 130–250°C and evaporative capacities of 5–5,000 kg/h water produce free-flowing powders of 10–300 µm — the preferred configuration for heat-sensitive biological, dairy, and food-grade spray drying.
Liquid feed is pumped to the centre of a rotating atomiser disc (10,000–25,000 RPM) at the top of the drying chamber. Centrifugal force throws the liquid as a thin film from the disc edge, which breaks into fine droplets (20–200 µm). Hot co-current air (130–250°C) contacts the droplets immediately — evaporating moisture within 5–30 seconds as droplets fall. Dried particles settle at the bottom, discharged by rotary valve; fines are collected in a cyclone separator. Exhaust air exits through a bag filter.
Challenges
Wide Particle Size Distribution
Disc speed and feed rate variation produces broad PSD beyond specification.
Wall Deposition of Sticky Products
High-sugar or fat-containing products adhere to drying chamber walls.
Heat-Sensitive Product Degradation
Inlet temperatures >180°C denature proteins and degrade thermolabile actives.
High Energy Consumption
Large air volumes at high temperature represent the dominant operating cost.
Powder Recovery from Cyclone
Fine particles <10 µm pass cyclone; require secondary bag filter for full recovery.
Solutions
- Atomiser Disc Speed VFD Control (10,000–25,000 RPM): Maintains target D50 ±10% across feed rate and viscosity changes.
- Chamber Wall Sweeping Air Broom: Continuous wall air sweep prevents sticky particle adhesion and chamber build-up.
- Two-Stage Drying (Low-Temperature Second Stage): Reduces outlet product temperature to <40°C for heat-sensitive materials.
- Heat Recovery from Exhaust Air: Exhaust air heat exchanger recovers 30–40% of energy; reduces operating cost.
- Integrated Cyclone + Bag Filter System: Sequential separation achieves >99.5% powder recovery from drying air.
Applications
- Food & Beverage: Milk powder, coffee, instant tea, flavour encapsulation, whey protein, infant formula.
- Pharmaceutical: API spray drying for bioavailability enhancement, excipient powder, inhalation formulations.
- Dairy: Full-cream milk powder, skim milk, lactose, whey powder, cheese powder production.
- Chemical: Detergent powder, ceramic powder, pigment powder, polymer microsphere drying.
- Nutraceuticals: Probiotic powder, enzyme powder, plant extract drying, sports nutrition powder.
Models & Capacities
6A — Rotary Atomiser Spray Dryer (SD-R) — 1 kg/h Lab to 5,000 kg/h Large Production — Disc 10,000–25,000 RPM — Droplet 20–200 µm — Powder 10–300 µm | ||||||||||
Model | Scale | Evap. Capacity [kg/h] | Feed Rate [L/h] | Inlet Air Temp [°C] | Outlet Air Temp [°C] | Disc Speed [RPM] | Droplet Size [µm] | Powder Size [µm] | Chamber Ø × H [mm] | Overall H [mm] |
SD-R-LAB-1 | Lab | 1 – 3 | 1 – 5 | 130 – 220 | 50 – 90 | 10,000 – 25,000 | 20 – 120 | 10 – 200 | Ø600 × 800 | 3,500 |
SD-R-PIL-10 | Pilot | 10 – 30 | 15 – 50 | 140 – 230 | 55 – 90 | 10,000 – 25,000 | 20 – 150 | 15 – 250 | Ø1,200 × 2,000 | 6,000 |
SD-R-50 | Production | 50 – 100 | 60 – 150 | 150 – 240 | 55 – 90 | 12,000 – 25,000 | 25 – 180 | 20 – 300 | Ø2,000 × 3,500 | 9,000 |
SD-R-200 | Production | 200 – 400 | 250 – 550 | 160 – 250 | 60 – 90 | 12,000 – 25,000 | 30 – 180 | 25 – 300 | Ø3,500 × 6,000 | 14,000 |
SD-R-500 | Production | 500 – 1,000 | 600 – 1,400 | 170 – 250 | 60 – 90 | 12,000 – 22,000 | 40 – 200 | 30 – 300 | Ø5,500 × 9,000 | 20,000 |
SD-R-2000 | Large Prod | 2,000 – 3,500 | 2,500 – 5,000 | 180 – 250 | 65 – 90 | 15,000 – 20,000 | 50 – 200 | 40 – 300 | Ø8,000 × 14,000 | 28,000 |
SD-R-5000 | Large Prod | 4,000 – 5,000 | 5,000 – 10,000 | 180 – 250 | 65 – 90 | 15,000 – 18,000 | 60 – 200 | 50 – 300 | Ø11,000 × 18,000 | 38,000 |