Solution
Closed-Loop Pellet Dewatering, Spiral Cooling, and Dedusting System
Integrated post-pelletiz…
Application
Continuous Polyolefin (PE / PP) Extrusion Pelletizing and Spiral Cooling Line
Polyolefin extrusion pelletizing plant profile covering water-ring die-face cutting, high-g centrifugal dewatering, spiral elevator cooling, and dedusting.
This industrial application profile outlines the continuous extrusion pelletizing, multi-stage water dewatering, and spiral cooling classification system engineered specifically for high-capacity polyolefin pelletizing plants running virgin polymer, re-compounded, or post-industrial polyethylene (LDPE, LLDPE, HDPE) and polypropylene (PP) compounds.
Polyolefin extrusion lines running at medium-to-large industrial capacities (500 kg/h to 3,000 kg/h) frequently encounter major operational bottlenecks in post-extrusion pellet processing: conventional strand cutting lines require excessive factory length (over 20 meters) and suffer from constant strand breakage when running flexible, low-crystallinity polyolefins like LLDPE or LDPE. Conversely, while water-ring die-face pelletizers eliminate strand guiding, the high volume of recirculating cutting water discharges hot (65°C–80°C), wet (0.5%–1.0% surface water) pellet slurry. If pellets are improperly dried or cooled before packaging, latent heat causes moisture re-condensation ("sweating") inside sealed 25 kg bags, triggering block caking, mold growth in organic additives, and feeding blockages in downstream extrusion hoppers. This application integrates a high-torque single or twin-screw extruder, die-face water ring pelletizer, vertical centrifugal dryer, continuous vibrating spiral cooling elevator, and linear dedusting screen, delivering bone-dry, cooled, and dust-free polyolefin pellets.
The scenario
Who runs it, what it makes, and what it must hold
Who it is for
Commercial polyolefin compounding plants, resin polymerization re-pelletizing facilities, and high-capacity post-industrial polyolefin recycling operations running continuous PE and PP extrusion lines.
Typical output
High-purity, free-flowing, bone-dry polyolefin pellets (cylindrical or lenticular shape, Ø2.5–3.2 mm) packaged in 25 kg valve bags or 1,000 kg bulk big bags, certified for high-speed blown film, pipe extrusion, and injection molding.
Production goal
Achieve continuous, high-speed polyolefin extrusion pelletizing with zero strand-break downtime, low plant footprint, and bone-dry, cooled pellets (surface moisture ≤ 0.05%, exit temperature ≤ 40°C).
Material
What the line is fed
The properties named here are the ones the equipment questions turn on — they are confirmed per project, from samples where it matters.
Thermoplastic polyolefin melts: HDPE, LDPE, LLDPE, and PP homopolymer / copolymer. Clean polymer melt delivered from single-screw or twin-screw extruder die head at temperatures of 170°C to 240°C.
Process
The typical flow, step by step
The flow is the usual shape of the scenario; the machines for each step are chosen per project — see the solutions below.
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Continuous Extrusion & Melt Delivery
Extrusion and Melt Processing
Melt-kneads polyolefin resin and delivers pressurized melt through a multi-orifice circular die plate.
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Die-Face Water-Ring Cutting
Pelletizing
Cuts molten strands into pellets right at the die face; high-velocity water ring sweeps pellets away instantly.
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High-G Centrifugal Dewatering
Post-Pellet Treatment
Separates water from pellets via high-speed centrifugal acceleration, reducing surface moisture to ≤ 0.05%.
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Vibrating Spiral Elevator Convective Cooling
Cooling
Elevates pellets vertically while convective air knives strip latent heat, cooling pellets from 75°C to ≤ 40°C within a small footprint.
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Linear Vibrating Screen Classification & Dedusting
Post-Pellet Treatment
Separates rare oversize agglomerates and dedusts micro-fines before discharging uniform pellets to packaging silos.
Requirements
What the process demands, and what quality is judged on
Critical process requirements
1. Centered Die-Face Cutting & Dynamic Blade Wear Compensation: Variable-speed cutter motor with pneumatic auto-advance keeps high-speed blades flat against the die plate, ensuring clean shear without “mushrooming” pellet heads.
2. High-G Centrifugal Dewatering: Vertical centrifugal dryer rotor operating at 900–1200 RPM expels > 99.8% of surface water within 1.5 seconds of slurry entry.
3. Vertical Spiral Extended Heat Dissipation: Vibrating spiral elevator provides 60–180 seconds of continuous vertical retention time, using counter-current air knives to dissipate core latent heat and cool pellets from 75°C to ≤ 40°C.
4. Linear Classification & Dedusting: Dual-deck linear screen removes rare oversized doublets and dedusts micro-fines before packaging.
Quality requirements
Residual Moisture: Surface moisture of finished pellets strictly ≤ 0.05% (500 ppm) upon exiting the screener.
Exit Temperature: Pellet discharge temperature ≤ 40°C at 25°C ambient, preventing thermal caking in bags.
Pellet Uniformity: Diameter variation within ±0.2 mm; zero agglomerated doublets or tailing whiskers.
Selection
What decides the equipment in this scenario
These are the questions a quotation is built from — answering them up front shortens the first round.
- Extruder with bimetallic screw & barrel
- High-capacity single or twin screw extruder with wear-resistant bimetallic flight cladding.
- Water-ring die-face pelletizer unit
- Direct-coupled cutting hood with stainless steel water ring vortex chamber and pneumatic blade adjustment.
- Vertical centrifugal dryer (SUS304)
- Dynamically balanced rotor with replaceable stainless steel wear plates and screen basket (Ø1.5–2.0 mm holes).
- Vibrating spiral elevator with forced air cooling
- Multi-tier SUS304 spiral tray powered by dual unbalance vibratory motors with convective cooling fans.
Fit
Where this scenario fits — and where it does not
The boundaries are part of the scenario: they keep equipment from being quoted into a case it cannot serve.
Best fit when
Best fit for high-output polyolefin pelletizing plants running virgin polymer, re-pelletized, or post-industrial PE (HDPE, LDPE, LLDPE) and PP lines with continuous capacities from 500 kg/h to 3,000 kg/h, where compact plant footprint (< 12 m line length) and zero pellet agglomeration/sweating are required.
Needs assessment when
Requires assessment when processing metallocene mLLDPE or high-melt-index injection grades (MFI > 30 g/10 min), where customized die-hole geometries and high cutting water circulation velocities are necessary to prevent die hole smear.
Not suitable when
Not suitable for water-soluble polymers (PVA) or ultra-low melting elastomers (Shore hardness < 50A, melting point < 65°C) which require specialized underwater cutting with refrigerated water circuits.
Variants
How the scenario splits
A variant is written down only where the process and the decision actually differ.
HDPE Pipe & Blow-Molding Grade Extrusion Pelletizing
- How it differs
High-density polyethylene (HDPE pipe, blow-molding, and film grades) with MFI 0.05 to 2.0 g/10 min.
- Process difference
Requires high-torque single/twin screw extruder with grooved feed section to handle high melt viscosity and prevent thermal surging.
- Output difference
High-crystallinity spherical/lens pellets with bulk density ≥ 0.55 kg/L and zero moisture retention.
LDPE / LLDPE Blown-Film Grade Extrusion Pelletizing
- How it differs
Low-density polyethylene (LDPE / LLDPE film grades) with MFI 1.0 to 10.0 g/10 min.
- Process difference
Requires vibrating spiral elevator equipped with forced ambient air blowers to ensure core cooling before bulk storage.
- Output difference
Uniform, flexible lenticular pellets suitable for high-speed blown film extrusion with zero air bubbles.
Photos
The scenario in practice
Photos go here once real views of this scenario are cleared to publish.
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Placeholder · 1200 × 900 px (4:3)（占位图） Replace with an approved application photo, real workshop or installation views at this size.（按此尺寸替换为正式图片。） -
Placeholder · 1200 × 900 px (4:3)（占位图） Replace with an approved application photo, real workshop or installation views at this size.（按此尺寸替换为正式图片。）
Before an inquiry
What we need to know to quote this scenario
- 01 Polyolefin grade and melt flow index (MFI) Polymer type (HDPE, LDPE, LLDPE, PP) and target MFI (g/10 min at standard test temperature/load).
- 02 Continuous production throughput (kg/h) Target hourly output capacity to size extruder screw, die plate hole count, and dewatering basket.
- 03 Factory floor layout and vertical height Available installation length (min 10–15 m) and ceiling headroom for spiral elevator (min 3.8–5.0 m).
- 04 Process cooling water and power supply Circulating cooling water supply (15–30 m³/h at 20°C–30°C) and 380V/415V 3-phase power.
Request a Quote Send these points with your inquiry; the scenario can then be quoted against your line, not against an assumption.
Where to go next
The solutions and the equipment this scenario names
Solutions for this scenario
Equipment for this scenario
