Twin screw pelletizer WRCE series

for plasticsfor plastic wastefor PE

The Challenge
Recycling plastic films, woven bags and fiber waste is difficult because these materials have very low bulk densities (0.03–0.12 g/cm³), resist feeding into conventional single-screw extruders, force high screw speeds (≈120 RPM) that create destructive shear heat, raise energy use to 350–500 kWh/ton, and lead to material degradation and inconsistent pellet quality.

The Solution: Counter-Rotating Twin Screw Technology
Our system uses two parallel screws rotating in opposite directions. As they intermesh their flights form sealed pockets that mechanically capture and positively displace material, achieving >95% volumetric conveying efficiency compared with 60–80% for drag-flow systems. The design conveys bulky, low-density feedstock reliably and allows operation at low rotational speeds (40–50 RPM) so that energy is focused on melting rather than overcoming feed resistance. The first counter-rotating stage runs below 2 MPa with no filtration; overall power consumption typically drops 30–40% across common applications.

Three-Stage Architecture
Stage | Function | Technology | Pressure
1 | Feeding, melting | Counter-rotating twin screw (L/D = 23–25) | <2 MPa
2 | Coarse filtration | Short single screw (L/D = 12) | 8–12 MPa
3 | Fine filtration, pelletizing | Short single screw (L/D = 10–12) | 15–20 MPa
This division lets each stage specialize: the twin-screw handles feeding/melting at low pressure, then two short single-screw stages build pressure for coarse and fine filtration and pelletizing. Where conventional agglomerator-based lines require ~272 kW installed power, the complete counter-rotating system can operate at ~165 kW while processing materials that traditional equipment cannot handle efficiently.

Operational Benefits

• Full throughput at just 40–50 RPM (about one-third the speed of single-screw alternatives).
• Zero back-pressure first stage concentrates energy on melting rather than overcoming resistance.
• Power consumption reduced by 30–40% in typical applications.
• Positive-displacement conveying prevents slip and instability with light, low-friction feed materials.

Applications and Material Scope

• Agricultural films (LDPE/LLDPE): greenhouse covers, mulch films, silage wrap — high moisture and soil contamination require effective feeding and venting.
• PP woven bags and jumbo bags: layered fabric and fiber bundles with extreme bulk density variation and occasional metal contamination (needles, staples, buckles) requiring robust protection.
• PP fiber and filament waste from textiles and carpets: bulk density 0.03–0.06 g/cm³, material so light it resists gravity feeding and can fluidize under small air movement.
• Industrial packaging films: stretch wrap, shrink film, bubble wrap — often multi-layer or printed, needing controlled melting to avoid ink dispersion or layer separation.
• Drip irrigation pipe and profile scrap: irregular shapes and potential metal inserts (e.g., fittings), requiring shear control and metal protection.

Supporting Technologies

• Permanent-magnet servo motors: ~93% efficiency even at partial loads; provide 100% rated torque at 1 RPM, matching low-speed/high-torque counter-rotating requirements.
• Electromagnetic induction heating: reaches operating temperature in ~5–10 minutes (vs. 20–30 minutes for conventional systems), reducing startup energy waste.

Key Advantages

• Efficient conveying: positive-displacement twin-screw conveying >95% volumetric efficiency, high throughput at low speed independent of material friction.
• Maximum energy savings: combined zero-back-pressure first stage, PM servo motors and electromagnetic heating yield 30–40% lower power consumption; e.g., PP fiber processing ≤260 kWh/ton vs. typical 400–500 kWh/ton.
• Optimized three-stage design: each stage focuses on feeding/melting, coarse filtration, or fine filtration/pelletizing.
• Material-specific engineering: ultra-deep screw channels, enlarged feed openings and tailored speed control to prevent wrapping and ensure stable feeding.
• Superior pellet quality: low-shear processing with precise temperature control (±1°C) minimizes thermal degradation, producing consistent MFI, zero bubbles and moisture <0.5%.
• Proven reliability: low-speed operation reduces mechanical wear; three-stage magnetic protection defends against metal contaminants; every system passes a 72-hour continuous running test before delivery.

Proven Performance (Representative)
Material | Bulk density | Our consumption | Typical industry
LDPE agricultural film | 0.08–0.12 g/cm³ | ≤220 kWh/ton | 350–400 kWh/ton
PP woven bags | 0.05–0.08 g/cm³ | ≤240 kWh/ton | 380–450 kWh/ton
PP fiber waste | 0.03–0.06 g/cm³ | ≤260 kWh/ton | 400–500 kWh/ton
For a standard 300 kg/h line running 24 hours, these differences translate to annual electricity savings typically in the range of 30,000 to 90,000 (currency units depend on local energy cost), often recovering equipment investment differentials within ~18–24 months.

Caractéristiques / Spécifications techniques

• Commercial designation: Counter-Rotating Twin Screw Pelletizing Line
• Screw architecture: counter-rotating twin screw first stage (L/D = 23–25); two short single-screw stages (L/D = 12 and L/D = 10–12)
• First-stage pressure: < 2 MPa; second-stage: 8–12 MPa; third-stage: 15–20 MPa
• Operating speed (first stage): typically 40–50 RPM
• Volumetric conveying efficiency: >95%
• Installed power (typical complete system): ~165 kW (vs. ~272 kW for comparable agglomerator-based lines)
• Guaranteed minimum throughput (example): ≥280 kg/h on PP fiber (line-dependent)
• Energy consumption targets: LDPE ≤220 kWh/ton; PP woven ≤240 kWh/ton; PP fiber ≤260 kWh/ton
• Pellet quality targets: MFI tolerance ±10%; moisture <0.5%; zero bubbles
• Heating: electromagnetic induction (5–10 min warm-up)
• Drive: permanent-magnet servo motors (~93% efficiency, full torque down to 1 RPM)
• Protection and reliability: three-stage magnetic protection, 72-hour continuous run test before shipment