A vacuum paste kettle is a sealed jacketed batch reactor operating at vacuum (−0.8 to −0.95 bar absolute) combined with steam or thermal oil heating (up to 200°C), enabling low-temperature evaporation, deaeration, and concentration of heat-sensitive, aroma-critical, or oxygen-sensitive paste materials at 1,000–300,000 cP across 50–3,000 L. Vacuum capability reduces the boiling point by up to 60°C, preserving volatile constituents and product colour.
The sealed vessel is evacuated to −0.8 to −0.95 bar before or during processing; the combination of reduced pressure and jacket heating drives moisture or solvent evaporation at temperatures 40–60°C below atmospheric boiling point. The anchor agitator (5–50 RPM) maintains bulk circulation while the wall-sweeping action continuously renews the evaporation surface. Vapour exits through the condenser; concentrate remains in the bowl. Vacuum-tight shaft seals and lid gaskets maintain system integrity throughout.
Challenges
Vacuum Seal Integrity at Agitator Shaft
Rotating shaft at vacuum differential stresses seal; any ingress breaks vacuum.
Foaming Under Vacuum
Rapid vapour generation in sugar or protein-containing pastes causes vigorous foaming.
Uniform Evaporation Rate Control
Non-uniform wall temperature creates localised dry spots in concentrated pastes.
Condensate Vapour Recovery
High-value volatile flavour compounds lost if condenser not properly sized.
CIP Under Vacuum-Tight Construction
All-welded vacuum-rated construction limits access for conventional CIP.
Solutions
- Double Mechanical Vacuum Shaft Seal (−0.95 bar Rated): Maintains vacuum integrity across 10,000+ hours of continuous agitation.
- Anti-Foam Spray Nozzle (Internal): Pre-measured anti-foam injection prevents foam overflow without product contamination.
- PLC Vacuum + Temperature Dual Control Loop: Coordinated pressure and temperature ramp preserves volatile aroma compounds.
- Integral Vapour Condenser (Surface Area Matched to Duty): Recovers condensed volatiles; option to return to vessel or collect separately.
- Full-Bore Bottom Outlet + CIP Spray Ball: Gravity-drainable vessel design with certified CIP spray coverage at all surfaces.
Applications
- Food & Beverage: Tomato paste concentration, fruit jam, jelly, and preserve production at low temperature.
- Pharmaceutical: Vacuum deaeration of ointment bases, suppository mass preparation, tablet coating concentrates.
- Cosmetics: Vacuum emulsification support, deaerated cream/lotion base preparation, wax blending.
- Dairy: Sweetened condensed milk, milk powder reconstitution, cream cheese concentration.
- Nutraceuticals: Heat-sensitive extract concentration, vitamin syrup deaeration, probiotic paste preparation.
Models & Capacities
4B — Vacuum Paste Kettle (PK-V) — 50 L to 3,000 L — 20–200°C — Vacuum 0.05–0.20 bar abs. — U 300–1,000 W/m²·K — Viscosity 1,000–300,000 cP | ||||||||||
Model | Capacity [L] | Motor [kW] | Agitator RPM | Vacuum Level [bar abs.] | Op. Temp [°C] | Jacket Pressure [bar] | U [W/m²·K] | Bowl Ø × H [mm] | Overall H [mm] | Weight [kg] |
PK-V-050 | 50 | 0.37 – 0.75 | 5–50 VFD | 0.05 – 0.20 | 20 – 200 | 1 – 6 | 300 – 900 | Ø500 × 380 | 1,800 | 120 |
PK-V-100 | 100 | 0.55 – 1.1 | 5–50 VFD | 0.05 – 0.20 | 20 – 200 | 1 – 6 | 350 – 950 | Ø650 × 460 | 2,100 | 200 |
PK-V-200 | 200 | 1.1 – 2.2 | 5–40 VFD | 0.05 – 0.20 | 20 – 200 | 1 – 6 | 350 – 1,000 | Ø800 × 570 | 2,500 | 360 |
PK-V-500 | 500 | 2.2 – 4.0 | 5–35 VFD | 0.05 – 0.20 | 20 – 200 | 1 – 6 | 400 – 1,000 | Ø1,050 × 750 | 3,100 | 650 |
PK-V-1000 | 1,000 | 4.0 – 7.5 | 5–30 VFD | 0.05 – 0.20 | 20 – 200 | 1 – 6 | 350 – 950 | Ø1,350 × 970 | 3,800 | 1,200 |
PK-V-3000 | 3,000 | 11 – 22 | 5–20 VFD | 0.05 – 0.20 | 20 – 200 | 1 – 6 | 300 – 900 | Ø1,900 × 1,400 | 5,200 | 3,200 |
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