Closed-Loop Pellet Dewatering, Spiral Cooling, and Dedusting System

This solution provides an integrated post-pelletizing dewatering, active continuous cooling, and precision classification system engineered specifically for strand pelletizing, water-ring pelletizing, and underwater pelletizing lines. Installed directly downstream of the extruder pelletizer cutter, it rapidly captures water-slurry pellet streams, removes over 99.8% of surface moisture through high-g centrifugal acceleration, gently elevates and cools pellets to safe packaging temperatures (≤ 40°C) via a vibrating spiral tower, and classifies the stream through a double-deck linear vibrating screen to completely separate oversize agglomerates and micro-fines.

In modern high-capacity compounding and recycling operations, high extruder throughput often overwhelms traditional horizontal cooling troughs or passive fluid beds, resulting in hot, moist pellets entering packaging silos. When packed hot (> 50°C), residual latent heat causes thermal sticking, clump formation inside 25 kg bags or bulk containers, and condensation-induced mold or hydrolysis during maritime export. Furthermore, uncut pellet stringers and knife dust contaminate the product stream. This engineered system delivers bone-dry, cool, and perfectly calibrated pellets ready for immediate automated bagging or bulk container loading.

The problem

What the section changes

Removes > 99.8% surface moisture and cools pellets to ≤ 40°C while eliminating agglomerates and knife dust prior to packaging.

Dónde empieza el cliente

Compounding and recycling lines rely on basic water troughs and rudimentary gravity mesh chutes or undersized standalone spin dryers. Hot, wet pellets exit the dryer at 65°C–80°C with 0.3%–1.0% residual surface moisture and are blown directly into packaging silos via pneumatic blowers.

Inside sealed packaging bags or Gaylord boxes, moisture cannot escape, resulting in clumped, caked pellets, hydrolysis degradation (especially in PET/PA), and frequent nozzle blockages on customer injection molding machines. Furthermore, un-scalped pellet stringers, tails, and knife cut fines lead to customer rejections.

Por qué ocurre el problema

Water-ring and underwater pelletizing systems rely on turbulent water flumes to instantly solidify hot polymer melts extruded through die holes. While water rapidly freezes the pellet outer shell, substantial latent heat remains trapped within the pellet core. If water removal is sluggish, residual surface water remains on the pellet.

Conversely, if pellets are dried centrifugally without active post-cooling, internal heat migrates to the surface, causing pellets to soften and fuse into large agglomerated clumps in the storage bin. Simultaneously, cutter blade wear produces micro-fines and stringers that create nozzle clogs during injection molding.

Producción o estado objetivo

A continuous stream of cool (≤ 40°C), bone-dry (surface moisture ≤ 0.05%), and precisely sized pellets free from oversize agglomerates, long stringers, and knife dust, feeding directly into automatic bagging or bulk silo storage.

Process

The steps, in the order the material flows

Centrifugal High-G Mechanical Dewatering
Required

Post-Pellet Treatment

High-g centrifugal separation of transport water from pellet slurry, casting water outward through a cylindrical screen while driving dry pellets upward.

Función del equipo
Rotor paddles rotating at 900–1200 RPM accelerate the pellet slurry. Centrifugal force drives 99.8% of surface water through the 1.5–2.0 mm screen holes into the lower sump, discharging dried pellets from the top outlet.

Equipos Vertical Centrifugal Dryer Underwater Pelletizing Dehydrator
Vibrating Spiral Active Cooling & Elevation
Required

Cooling

Vertical conveyance while continuously tumbling and actively chilling ascending pellets with high-velocity filtered air knives.

Función del equipo
Dual synchronized vibration motors induce non-shearing micro-hops along a continuous upward spiral flight path (60–120 s retention time). Low-noise centrifugal blowers force ambient or chilled air through the fluidizing pellet bed, dropping core temperature from 75°C to ≤ 40°C.

Equipos Vibrating Spiral Elevator
Double-Deck Dedusting and Classification
Required

Post-Pellet Treatment

Multi-deck linear vibration classification to scalp off oversize agglomerates and separate fine knife dust.

Función del equipo
Linear dual-motor exciter drives pellets along a double-deck screen. Top deck rejects long stringers and agglomerates (> 4.5 mm); bottom deck discards fine shavings and dust (< 1.5 mm); qualified pellets discharge from center outlet.

Equipos Linear Vibrating Screen
Water Closed-Loop Filtration & Recirculation
Required

Pelletizing

Continuously captures separated cooling water, removes stray fines via wedge-wire filter, and pumps water back to pelletizer cutting chamber.

Función del equipo
Stainless steel balance tank with inline basket filter and booster pump maintains closed-loop water circulation, minimizing plant water consumption and thermal energy loss.

Material

What goes in, what comes out

Condición y requisitos de alimentación

Continuous pellet-water slurry discharged directly from strand pelletizing troughs, water-ring pelletizers, or underwater cutting chambers. Water flow rate up to 40 m³/h; pellet slurry temperature typically 45°C to 75°C. Polymer pellets: PP, HDPE, LDPE, PET, ABS, HIPS, PC, PA, filled compounds.

Condición y límites de salida

Bone-dry, dust-free, and uniformly cooled thermoplastic pellets. Residual surface moisture ≤ 0.05% (500 ppm), pellet discharge temperature ≤ 40°C, zero oversized agglomerates/twins, and fines (< 1.5 mm) content ≤ 0.05% by mass. Ready for immediate automated bagging or bulk container loading.

300–2500 kg/h

Base de las cifras de capacidad

Based on continuous inline operation matched to a single or twin screw extruder pelletizing line with throughput ratings from 300 kg/h up to 2,500 kg/h, handling pellet bulk densities of 0.45–0.75 kg/L.

Fit

Where this section belongs — and where it does not

Adecuada cuando

Essential for high-output compounding lines (500–2,500 kg/h) operating water-ring pelletizers or underwater pelletizers where traditional horizontal vibration tables lack sufficient retention time to cool pellets.

Crucial for polymers intended for maritime container export, where hot-caked pellets or residual moisture trigger catastrophic condensation, clump solidification, or hydrolytic degradation inside bulk liners.

No adecuada cuando

Not suitable for un-pelletized plastic scrap, un-granulated film bales, or dense plastic purging blocks. Size reduction equipment (shredders/crushers) must precede this process.

Not suitable for high-melt-strength polymers processed via dry-face strand lines where no water slurry is utilized (e.g., hot air-blown strand lines).

Condiciones pendientes de confirmar

Calculations assume standard rigid polyolefin or engineering thermoplastic pellets (PP, HDPE, ABS, PET, PC) with initial pellet slurry water-to-granule ratios between 10:1 and 25:1. Pellets must have attained sufficient core solidification prior to centrifugal dryer entry to prevent blade distortion.

For low-melting or sticky thermoplastic elastomers (TPU, TPE, EVA > 20% VA), a water-cooled hollow flight vibrating spiral elevator and anti-stick fluoropolymer screen coatings are required.

Site and connections

What the section assumes around it

Servicios auxiliares

Suministro eléctrico: 380 V / 415 V / 460 V, 50/60 Hz, 3-phase AC.
Agua: Standard industrial cooling water for makeup (clean soft water or softened loop).
Aire comprimido: 0.5–0.6 MPa clean, dry compressed air for pneumatic screen cleaner and spray wash valves (intermittent ~0.1 m³/min).
Extracción y ventilación: Dryer top exhaust port DN150 to discharge hot, humid air; optional mist eliminator ducting.

Total connected electrical power: 15 kW to 37 kW depending on line output capacity.

Limitaciones de la planta

Superficie ocupada: Compact footprint: approximately 10–16 m² total for spin dryer, water tank, spiral elevator, and linear screener.
Altura libre: Vertical clearance of 3.8 m to 4.8 m required for vibrating spiral elevator tower.
Entorno: Indoor plant environment; floor trench or drainage sump recommended near centrifugal dryer base.

Vibration isolation rubber dampers and heavy helical springs isolate > 95% of dynamic vibratory force from building floor.

Interfaces

Mecánico: DN80 / DN100 slurry pipe inlet; DN100 process water return drain flange; DN150 pellet discharge chutes for good pellets, overs, and fines.
Control: Integrated electrical cabinet with safety interlocks; hardwired interlock to extruder master stop circuit in case of dryer or screener trip.
Aguas arriba y aguas abajo: Upstream: pelletizer cutting chamber slurry flume. Downstream: pneumatic transfer hopper, bagging bin, or storage silo.

Targets

What the section is judged on

Discharged Pellet Surface Moisture: ≤ 0.05% (500 ppm) % Halogen moisture analyzer test at 105°C on exit pellets
Pellet Packaging Temperature: ≤ 40 °C Calibrated infrared surface thermometer / thermocouple probe
Fines and Dust Content (< 1.5 mm): ≤ 0.05% % Standard laboratory vibration sieve analysis per ASTM D1921

Cómo se evalúa la aceptación

Tested continuously over a 4-hour full-load production run on the customer’s compounding line at the agreed nominal output rate. Surface moisture of discharged pellets sampled directly at the screen discharge chute is verified via halogen moisture analyzer (105°C / 10 min) to be ≤ 0.05% (500 ppm).

Pellet surface temperature measured via infrared pyrometer must register ≤ 40°C under ambient plant conditions (≤ 28°C ambient). Sieve analysis of the finished product bin must confirm 0.00% oversized stringers (> 5 mm) and fines content (< 1.5 mm) below 0.05% by mass.

Scope of supply

What is in the delivery — and what is not

Incluido en el alcance del suministro

Vertical Centrifugal Spin Dryer (SUS304) Centrifugal rotor with tungsten-carbide coated wear tips, high-precision cylindrical screen basket, pneumatic spray wash bar, and water collection basin.
Vibrating Spiral Cooling Elevator Tower SUS304 continuous welded flight elevator, dual contra-rotating unbalance vibration motors, modular stainless steel dust covers, and centrifugal forced-air cooling blowers.
Linear Vibrating Screening Machine (Double-Deck) Top scalping deck (4–5 mm) for agglomerates/stringers, bottom dedusting deck (1.5–2 mm), quick-clamp inspection hood.
Closed-Loop Water Filtration & Circulation Tank Wedge-wire mesh screen filter basket, stainless water pump, and automatic water level makeup float valve.

No incluido en el alcance del suministro

Extruder, die plate, and pelletizer cutter head Upstream melt processing, die faces, and rotating pelletizer knives are separate equipment scope.
Process cooling water chiller plant and external cooling tower Central cooling tower and chiller supply loop outside the skidded dewatering package are customer scope.
Finished product packaging machines and robotic cells Downstream FFS baggers, checkweighers, and stretch wrappers unless explicitly quoted in turnkey package.
Interconnecting piping exceeding 5 meters beyond machine skid boundaries Long-distance civil piping runs are provided by the client.

Before a price

What we confirm before this becomes a quotation

01 Extruder throughput and pellet cut geometry Maximum line output (kg/h), pellet shape (lens, cylindrical, spherical), and nominal pellet cut size (e.g., Ø3 mm x 3 mm).
02 Polymer formulation and thermal characteristics Resin type, melting point (Tm), glass transition temperature (Tg), and presence of sticky tackifiers or plasticizers.
03 Process water loop specifications Cooling water supply temperature, circulation flow rate (m³/h), and available water filtration/chiller capacity.
04 Downstream packaging transfer distance and height Layout coordinates from extruder die face to packaging bin or storage silo to optimize spiral elevator height and piping runs.

Request a Quote Send these points with your inquiry; the section can then be quoted against your line, not against an assumption.

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Photos

The section in the workshop

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Placeholder · 1200 × 900 px (4:3)（占位图） Replace with an approved section photos, real workshop or installation views at this size.（按此尺寸替换为正式图片。）

Details

Further details

Problema de producción principal

High surface moisture on the material
Off-spec pellet size and fines
Sticking and agglomeration