A helical agitator is a low-speed, high-torque mixing device with a helical ribbon or screw impeller operating at 5-60 RPM (tip speed 0.1-1.5 m/s) under laminar conditions (Re <10) for ultra-high-viscosity fluids from 10,000 to 1,000,000+ cP. Close-clearance wall contact generates full vessel top-to-bottom axial circulation, eliminating dead zones and delivering heat-transfer coefficients of 300-1,000 W/m2K in jacketed CSTR and batch reactors.
Ultra-viscous material is charged into the vessel; the helical impeller engages material across the full vessel height at low speed. Upward axial flow along the wall and downward return through the core create continuous laminar circulation loops eliminating stagnant zones throughout the vessel. Power input of 2-15 kW/m3 maintains controlled shear without structural material damage. CIP/SIP-compatible geometry allows in-place cleaning and sterilisation between batches.
Challenges
High Torque Requirement
Very high viscosity demands oversized bevel-helical or worm gearboxes and reinforced shafts.
Low Turbulence and Limited Dispersion
Laminar regime prevents fine emulsification or high-rate gas-liquid mass transfer.
Complex Fabrication
Helical ribbon geometry requires precise dimensional control and specialist fabrication.
Mechanical Load on Shaft and Bearings
High viscous drag creates significant bending and torsional shaft loading.
Cleaning Complexity
Close wall-clearance geometry (5-10 mm) requires validated CIP spray coverage.
Scale-Up Non-Linearity
Power per unit volume increases with vessel diameter under laminar conditions.
Solutions
- Close-Clearance Helical Geometry (5-10 mm Wall Gap): Minimises dead volume; maximises thermal boundary layer renewal at vessel wall.
- High-Torque Helical-Bevel Gearbox: Rated at 2x peak viscosity torque; flanged mounting provides rigid shaft support.
- VFD with Torque Limiting: Soft-start and real-time torque monitoring prevent gearbox overload at cold-batch startup.
- Integrated CIP/SIP Design: Spray nozzle coverage validated for helix pitch and wall gap; no disassembly required.
- Combination with Disperser or Cowl: Secondary high-shear device handles emulsification; helical maintains bulk circulation.
- Froude Number Scale-Up: Fr matching between pilot and production ensures equivalent circulation and heat transfer.
Applications
- Chemical: Polymers, resins, adhesives, viscous reaction systems requiring full top-to-bottom turnover.
- Pharmaceutical: Ointments, gels, creams, high-viscosity oral and topical formulations under GMP.
- Food & Beverage: Dough, pastes, chocolate, thick sauces, jam, and confectionery bases.
- Cosmetics: Creams, body butter, lotions, gels, and emulsified viscous personal care products.
- Paints & Coatings: High-viscosity coatings, pigment pastes, and specialty thick-film formulations.
- Dairy: Processed cheese, concentrated dairy products, and high-viscosity cream processing.
- Specialty Chemicals: Non-Newtonian slurries, pseudoplastic systems, and high-fill-ratio polymer composites.
Models & Capacities
Model | Impeller Type | Scale | Vessel Vol [L] | Impeller Ø D [mm] | D / T Ratio | Wall Clearance [mm] | Helix Pitch [mm] | Speed [RPM] | Tip Speed [m/s] | Motor Power [kW] | Power Density [kW/m³] | Viscosity Range [cP] | U [W/m²·K] | Re (max) | |
Single Helical Ribbon (HR) — 2 L Lab to 50,000 L Large Production — Standard Close-Clearance Ribbon; Laminar Full-Vessel Circulation; Jacketed CSTR & Batch | |||||||||||||||
HEL-HR-LAB-5 | Single Ribbon | Lab | 2 – 5 | 170 – 220 | 0.93 – 0.97 | 5 – 8 | 85 – 175 | 30 – 60 | 0.3 – 0.7 | 0.02 – 0.12 | 3 – 8 | 10,000 – 1,000,000 | 400 – 800 | < 1 | |
HEL-HR-LAB-20 | Single Ribbon | Lab | 5 – 20 | 220 – 340 | 0.93 – 0.97 | 5 – 8 | 110 – 270 | 20 – 50 | 0.2 – 0.9 | 0.05 – 0.35 | 3 – 8 | 10,000 – 1,000,000 | 400 – 850 | < 2 | |
HEL-HR-PIL-100 | Single Ribbon | Pilot | 20 – 100 | 340 – 560 | 0.93 – 0.97 | 5 – 8 | 170 – 450 | 15 – 40 | 0.3 – 1.2 | 0.20 – 1.2 | 2 – 8 | 10,000 – 1,000,000 | 400 – 900 | < 3 | |
HEL-HR-PIL-500 | Single Ribbon | Pilot | 100 – 500 | 550 – 940 | 0.93 – 0.97 | 6 – 10 | 275 – 750 | 10 – 30 | 0.3 – 1.5 | 0.5 – 6.0 | 2 – 8 | 10,000 – 1,000,000 | 420 – 920 | < 5 | |
HEL-HR-P-2000 | Single Ribbon | Production | 500 – 2,000 | 900 – 1,500 | 0.92 – 0.97 | 6 – 10 | 450 – 1,200 | 8 – 25 | 0.4 – 2.0 | 2 – 18 | 2 – 10 | 10,000 – 1,000,000 | 450 – 1,000 | < 8 | |
HEL-HR-P-10000 | Single Ribbon | Production | 2,000 – 10,000 | 1,500 – 2,700 | 0.92 – 0.96 | 7 – 12 | 750 – 2,150 | 5 – 18 | 0.4 – 2.5 | 8 – 80 | 2 – 10 | 10,000 – 1,000,000 | 450 – 1,000 | < 10 | |
HEL-HR-LP-50000 | Single Ribbon | Large Prod | 10,000 – 50,000 | 2,700 – 5,000 | 0.92 – 0.96 | 8 – 15 | 1,350 – 4,000 | 5 – 12 | 0.7 – 3.1 | 30 – 350 | 2 – 8 | 10,000 – 500,000 | 450 – 950 | < 12 | |
Double Helical Ribbon (DHR) — 20 L Pilot to 10,000 L Production — Counter-Wound Inner + Outer Ribbons; Enhanced Top-to-Bottom Axial Turnover; Higher Power Density | |||||||||||||||
HEL-DHR-PIL-100 | Double Ribbon | Pilot | 20 – 100 | 340 – 560 | 0.93 – 0.97 | 5 – 8 | 170 – 450 | 15 – 40 | 0.3 – 1.2 | 0.30 – 1.5 | 3 – 10 | 10,000 – 1,000,000 | 450 – 950 | < 3 | |
HEL-DHR-PIL-500 | Double Ribbon | Pilot | 100 – 500 | 550 – 940 | 0.93 – 0.97 | 6 – 10 | 275 – 750 | 10 – 30 | 0.3 – 1.5 | 0.8 – 8.0 | 3 – 10 | 10,000 – 1,000,000 | 480 – 1,000 | < 5 | |
HEL-DHR-P-2000 | Double Ribbon | Production | 500 – 2,000 | 900 – 1,500 | 0.93 – 0.97 | 6 – 10 | 450 – 1,200 | 8 – 25 | 0.4 – 2.0 | 3 – 22 | 3 – 12 | 10,000 – 1,000,000 | 500 – 1,000 | < 8 | |
HEL-DHR-P-10000 | Double Ribbon | Production | 2,000 – 10,000 | 1,500 – 2,700 | 0.93 – 0.97 | 7 – 12 | 750 – 2,150 | 5 – 18 | 0.4 – 2.5 | 12 – 100 | 3 – 12 | 10,000 – 1,000,000 | 500 – 1,000 | < 10 | |
Helical Ribbon + Centre Screw (HR+CS) — 50 L Pilot to 20,000 L Large Production — Ultra-High Viscosity; Core Screw Drives Downward Return; Minimum Dead Volume | |||||||||||||||
HEL-HRCS-PIL-200 | Ribbon + Screw | Pilot | 50 – 200 | 450 – 760 | 0.92 – 0.97 | 5 – 8 | 225 – 600 | 10 – 30 | 0.2 – 1.2 | 0.5 – 3.5 | 3 – 12 | 50,000 – 1,000,000 | 480 – 1,000 | < 2 | |
HEL-HRCS-P-1000 | Ribbon + Screw | Production | 200 – 1,000 | 700 – 1,200 | 0.92 – 0.97 | 6 – 10 | 350 – 960 | 8 – 20 | 0.3 – 1.3 | 1.5 – 15 | 3 – 12 | 50,000 – 1,000,000 | 480 – 1,000 | < 3 | |
HEL-HRCS-P-5000 | Ribbon + Screw | Production | 1,000 – 5,000 | 1,200 – 2,100 | 0.92 – 0.96 | 7 – 12 | 600 – 1,680 | 5 – 15 | 0.3 – 1.6 | 6 – 60 | 3 – 15 | 50,000 – 1,000,000 | 490 – 1,000 | < 5 | |
HEL-HRCS-LP-20000 | Ribbon + Screw | Large Prod | 5,000 – 20,000 | 2,100 – 3,700 | 0.92 – 0.96 | 8 – 15 | 1,050 – 2,960 | 5 – 10 | 0.5 – 2.0 | 25 – 200 | 3 – 12 | 50,000 – 1,000,000 | 490 – 1,000 | < 8 | |