Low-temperature drying unit PRBD series

for the pharmaceutical industryfor the food industry

Overview
Pull the vessel down to 10–100 mbar absolute so water boils between 7 °C and 46 °C. A vacuum ribbon mixer/dryer strips moisture or solvent from heat-sensitive products at jacket temperatures a conventional dryer cannot reach while the ribbon agitator keeps the bed turning so every particle sees the heated wall and no crust forms.

Key performance stats

• Vacuum range: 10 – 200 mbar
• Final moisture: < 0.1% w/w (typical)
• Evaporation rate: 4 – 12 kg/m²·h
• Cycle time: 2 – 12 h (including drying)

Principle
Lower the pressure, lower the boiling point. Operating a jacketed ribbon mixer under vacuum reduces boiling point and enables drying, degassing or reaction at low product temperatures.

Absolute pressure table
1013 mbar | Water boils at 100 °C | Atmospheric reference
200 mbar | 60 °C | Light de-dusting, degassing
100 mbar | 46 °C | Food powders, botanicals
50 mbar | 33 °C | Proteins, enzymes, probiotics
20 mbar | 18 °C | APIs, solvent recovery
10 mbar | 7 °C | Battery materials, deep drying

Primary duties and features

• One vessel for mixing, reaction or wet granulation, then in-vessel drying to target LOD without product transfer.
• Vapour recovery via shell-and-tube or plate condenser, receiver and cold trap sized to evaporation duty; solvents recovered as liquid for reuse.
• Oxygen-free processing: evacuate and back-fill with nitrogen for oxidation-sensitive or dust-explosive products. ATEX execution and inert-loop control available.

Where vacuum mixing and drying is used (Applications)

• Pharmaceutical & API – wet granulation and in-vessel drying; solvent recovery and containment. Typical: 10 – 30 mbar, jacket 40 – 60 °C.
• Nutraceutical & Protein Powders – drying botanical extracts, probiotics and protein isolates without denaturation; product ≤ 45 °C, typical 30 – 80 mbar.
• Food & Beverage – flavour bases, instant powders, cook under jacket then flash-cool under vacuum; typical 50 – 150 mbar.
• Battery & Energy Materials – cathode/anode precursors to single-digit ppm moisture, NMP recovery, inert atmosphere; ≤ 10 mbar with N2 back-fill.
• Specialty Chemicals – pigments, catalysts, resins; reaction under vacuum then dry and cool in same body; typical 10 – 100 mbar.
• Plastics, Polymers & Minerals – drying and degassing of resins, masterbatch and technical ceramics; jacket to 150 °C, typical 50 – 200 mbar.

Temperature control: Heating, Cooling, Vacuum
The ribbon agitator renews the layer at the wall so the agitator acts as a heat-transfer device as well as mixing. Adding vacuum provides independent control by lowering the boiling point and improving wall-to-bed heat transfer.

Heating, Cooling and Vacuum options

• Heating: steam, thermal oil or electrically heated fluid through dimpled, half-pipe or limpet-coil jacket on trough and end plates. Hollow-shaft and hollow-ribbon options add interior heating surface. Ranges: steam to 150 °C, oil to 250 °C, electric to 200 °C.
• Cooling: chilled water or glycol through the same jacket circuit for cook & chill, frictional heat removal, or holding exotherms. Chilled water to 4 °C, glycol to −20 °C; CO2 optional.
• Vacuum as thermal control: 10 – 200 mbar giving boiling point 7 – 60 °C and enabling flash-cooling.

Jacket construction & control

• ASME-certified jackets rated to 6 bar (90 PSI); dimple, half-pipe or limpet coil selected by duty and fluid.
• Hollow shaft and hollow ribbon options raise heat-transfer area per litre by up to 45%.
• Jacket zoning on trough, end plates and doors so the whole wetted wall is active.
• Product RTDs in the bed for direct product temperature control.
• PLC recipe control with ramp, soak, cool and vacuum set-points plus batch data logging.
• Rock-wool or aerogel insulation with stainless cladding; surface held below 60 °C for operator safety.

Comparison: Ribbon Mixer vs Vacuum Ribbon Mixer/Dryer
Primary duty | Ribbon Mixer (PRB / PVR) | Vacuum Mixer/Dryer (PRBD / PVRD)
Operating pressure | Atmospheric, optional light purge | 10 – 200 mbar absolute
Vessel construction | Open-top trough or tank, gasketed cover | Pressure/vacuum-rated body, full-penetration welds
Jacket | Optional | Standard, ASME to 6 bar
Shaft sealing | Packed gland or air purge | Double mechanical seal, vacuum-rated
Ancillaries | Feeders, dust filter | Vacuum pump, condenser, receiver, cold trap, filter
Moisture removal | None | To below 0.1% w/w, product-dependent
Solvent recovery | Not applicable | Closed-loop condensation and reuse
Heat-sensitive product | Handled by cooling only | Dries at 30 – 50 °C product temperature
Oxidation / dust risk | Managed by inert purge | Evacuate and N2 back-fill; inherently oxygen-free
Cycle time | 3 – 20 min | 2 – 12 h including drying
Installed power (1,000 L) | 11 kW | 18.5 kW plus vacuum skid
Relative capital | Baseline | 2.5 – 4× baseline, ancillaries included
Replaces | — | A separate mixer, tray/fluid-bed dryer and the transfer between them
Choose it when | Product arrives dry and leaves dry | Moisture, solvent, oxygen or heat sensitivity is part of the spec

Specifications tables
Notes: dimensions in mm; PRBD kW and RPM shown for jacketed vacuum execution and vary with product viscosity and drying duty. Mixers can be built to a total volume of up to 30,000 L.

Horizontal Vacuum Ribbon Mixers/Dryers · PRBD Series
PRBD-5L-CP | Total 5 L | Work 40% 2 L | Work 60% 3 L | kW 1.1 | RPM 256 | L 950 | W 900 | H 610 | kg 140
PRBD-10L-CP | Total 10 L | Work 40% 4 L | Work 60% 6 L | kW 1.1 | RPM 256 | L 1,050 | W 900 | H 610 | kg 160
PRBD-15L-CP | Total 15 L | Work 40% 6 L | Work 60% 9 L | kW 2.2 | RPM 196 | L 1,150 | W 1,000 | H 640 | kg 180
... (PRBD models up to PRBD-3000 as per series data) ...

Vertical Vacuum Ribbon Mixers/Dryers · PVRD Series
PVRD-15 | Total 15 L | Work 30% 4 L | Work 70% 10 L | kW 1.5 | RPM 92 | Dia. 450 | H 1800 | kg 180
PVRD-20 | Total 20 L | Work 30% 6 L | Work 70% 14 L | kW 1.5 | RPM 77 | Dia. 550 | H 2100 | kg 240
PVRD-30 | Total 30 L | Work 30% 9 L | Work 70% 21 L | kW 2.2 | RPM 77 | Dia. 550 | H 2100 | kg 340
... (PVRD models up to PVRD-4000 as per series data) ...

FAQ highlights

• At 10–100 mbar absolute pressure, water boils between 7 °C and 46 °C so most products dry at 30–50 °C product temperature; heat-sensitive materials retain activity, colour and aroma.
• Final moisture: below 0.1% w/w on most products; single-digit ppm moisture achievable for battery-grade materials under deep vacuum with N2 back-fill.
• Solvent recovery: closed-loop vapour system (condenser, receiver, cold trap) recovers solvents as liquid for reuse; standard practice for API, NMP and specialty chemical duties.