A steam-jacketed paste kettle is a hemispherical or cylindrical batch reactor with a full steam jacket (1–6 bar, up to 165°C steam temperature) and a low-speed anchor or gate agitator (5–60 RPM) for cooking, dissolving, and temperature-controlled processing of high-viscosity pastes at 5,000–500,000 cP. Capacities of 50–5,000 L deliver U = 300–1,000 W/m²·K for uniform heat distribution without localised scorching.
Product is charged into the kettle bowl; steam enters the annular jacket at regulated pressure, heating the vessel wall uniformly. The anchor or gate agitator (5–60 RPM) continuously sweeps the heated wall — renewing the thermal boundary layer and preventing scorching of viscous, sugar-based, or starch-based materials. Condensate is drained continuously to maintain steam quality. Temperature is controlled by modulating steam supply pressure via PLC, achieving ±2°C setpoint accuracy.
Challenges
Localised Scorching at Wall
Stagnant viscous layer overheats between agitator passes, degrading product.
Steam Pressure Limitation (6 bar / 165°C)
Maximum jacket temperature limits processing of products requiring >165°C.
Inconsistent Mixing in Large Batches
Single anchor sweep may leave central bulk poorly circulated in vessels >2,000 L.
Condensate Accumulation in Jacket
Waterlogging reduces effective steam contact area and lowers heat transfer rate.
Open Atmosphere Losses
Moisture evaporation and volatile flavour loss occur in open-top configurations.
Solutions
- Close-Clearance Anchor (5–10 mm Wall Gap): Wall sweep frequency matched to product viscosity prevents scorching.
- Condensate Trap with Steam Trap on Jacket Outlet: Continuous condensate removal maintains full steam contact across jacket area.
- Dual Anchor + Central Stirrer Configuration: Secondary central stirrer eliminates bulk dead zone in large kettle volumes.
- PLC Steam Pressure Modulation (±2°C): Proportional steam valve maintains precise cooking temperature throughout batch.
- Lid or Cover Option: Reduces evaporative loss and minimises volatile flavour compound loss during cooking.
Applications
- Food & Beverage: Jam, jelly, sauce, confectionery, chocolate, starch paste cooking and blending.
- Pharmaceutical: Ointment base preparation, suppository mass cooking, tablet coating solution heating.
- Cosmetics: Wax melting, cream base cooking, lipstick mass preparation, hair wax processing.
- Dairy: Processed cheese cooking, butter blending, sweetened condensed milk processing.
- Nutraceuticals: Syrup concentration, honey processing, viscous supplement base preparation.
Models & Capacities
4A — Steam-Jacketed Paste Kettle (PK-S) — 50 L to 5,000 L — Up to 165°C — 1–6 bar Steam — U 280–1,000 W/m²·K — Viscosity 5,000–500,000 cP | ||||||||||
Model | Capacity [L] | Motor [kW] | Agitator RPM | Steam Pressure [bar] | Op. Temp [°C] | U [W/m²·K] | Jacket Area [m²] | Bowl Ø × H [mm] | Overall H [mm] | Weight [kg] |
PK-S-050 | 50 | 0.37 – 0.75 | 5–60 VFD | 1 – 6 | Up to 165 | 300 – 800 | 0.4 | Ø500 × 380 | 1,600 | 90 |
PK-S-100 | 100 | 0.55 – 1.1 | 5–60 VFD | 1 – 6 | Up to 165 | 350 – 900 | 0.7 | Ø650 × 460 | 1,900 | 150 |
PK-S-200 | 200 | 1.1 – 2.2 | 5–50 VFD | 1 – 6 | Up to 165 | 350 – 950 | 1.2 | Ø800 × 570 | 2,300 | 280 |
PK-S-500 | 500 | 2.2 – 4.0 | 5–40 VFD | 1 – 6 | Up to 165 | 400 – 1,000 | 2.5 | Ø1,050 × 750 | 2,900 | 520 |
PK-S-1000 | 1,000 | 4.0 – 7.5 | 5–30 VFD | 1 – 6 | Up to 165 | 350 – 950 | 4.5 | Ø1,350 × 970 | 3,600 | 950 |
PK-S-2000 | 2,000 | 7.5 – 15 | 5–25 VFD | 1 – 6 | Up to 165 | 300 – 900 | 8.0 | Ø1,700 × 1,250 | 4,500 | 1,800 |
PK-S-5000 | 5,000 | 15 – 30 | 5–20 VFD | 1 – 6 | Up to 165 | 280 – 850 | 16 | Ø2,400 × 1,700 | 6,000 | 4,200 |
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