에이 plastic recycling drying line is the equipment cluster between a washing line and a pelletizer that reduces moisture from 30–70% (post-wash) down to the target your downstream process requires. The right line configuration depends on your input material, throughput, and end-product moisture spec — not on a one-size-fits-all template. This guide covers the five functional zones of a complete drying line, material-specific layouts for PET, HDPE/PP, and film, equipment sizing rules, buffer strategy, automation, and integration with both your washing line (upstream) and extruder (downstream).
If you’re researching whether you need a drying line, start with our plastic drying system pillar guide. If you’ve already chosen specific equipment and need help with procurement, see the industrial centrifugal dryer buyer’s guide. This article picks up after those decisions are made and focuses on how to lay out the line.
The 5 Functional Zones of a Plastic Recycling Drying Line
Every plastic recycling drying line, regardless of material or scale, contains the same five functional zones. The complexity (and capital cost) varies dramatically — but the structure is consistent.
- Reception zone — buffer hopper or vibrating screen that receives wet flakes from the washing line and feeds the dewatering equipment at controlled rate
- Mechanical dewatering zone — centrifugal dewatering machine, screw press, or film squeezer that removes bulk water at low energy cost (30–60 kWh/ton)
- Inter-stage buffer — silo or hopper between mechanical dewatering and thermal drying, sized to absorb 15–30 minutes of flow variation
- Thermal drying zone — pipeline hot air dryer, fluidized bed, or rotary drum that evaporates residual surface moisture (120–180 kWh/ton)
- Discharge & storage zone — final hopper or silo where dried flakes accumulate before feeding the extruder, with moisture monitoring and dehumidified air management
For PET applications, two additional zones sit between thermal drying and discharge: a crystallizer (sheet/bottle grades) and a desiccant pellet dryer (bottle-to-bottle only). These zones add $80,000–$200,000 to a 1 ton/h line but are non-negotiable for food-contact rPET.
Material-Specific Drying Line Configurations
The right plastic recycling drying line layout differs significantly by input material. Here are the four production-grade configurations covering 95% of real-world recycling operations.
Configuration A: PET Bottle Flake Drying Line (1,000–3,000 kg/h)
The most demanding drying line in plastic recycling. PET requires moisture below 50 ppm for bottle-to-bottle, hydrolyzes at extrusion temperatures with residual water, and softens above 75°C — driving a 4-stage configuration with strict temperature control.
- Stage 1 — Friction washer discharge → buffer hopper (5-min capacity) → horizontal centrifugal dewatering machine (45–55 kW for 1 ton/h, 75–90 kW for 2–3 ton/h). Outlet moisture: 2–4%.
- Stage 2 — Inter-stage buffer (15-min capacity, ~250 kg for 1 ton/h line) → pipeline hot air dryer at 145–155°C with PID temperature control (±2°C). Outlet moisture: 0.3–0.8%.
- Stage 3 — Crystallizer (fluidized bed, 130–160°C, 20–40 min residence). Required for sheet/bottle grades; converts amorphous PET to crystalline structure (non-tacky, heat-tolerant).
- Stage 4 — Desiccant pellet dryer (post-pelletizing, 170–180°C, dew-point ≤-40°C, 4–6 h residence). Required only for bottle-to-bottle grade; reaches 50 ppm.
Total drying section investment: $200,000–$400,000 for full bottle-to-bottle line; $80,000–$180,000 for sheet/fiber line (skip Stage 4); $30,000–$60,000 for strapping/fiber line (Stages 1+2 only). For complete PET-specific guidance, see our PET flake dryer guide.
Configuration B: HDPE / PP Rigid Drying Line (500–2,500 kg/h)
HDPE and PP tolerate 3–5% moisture into the extruder for most applications (pipe, pallet, sheet). The drying line is significantly simpler than PET — typically just centrifugal dewatering, with thermal drying optional for premium-grade output.
- Standard configuration: Friction washer → buffer hopper → centrifugal dewatering machine (vertical 22–37 kW for under 800 kg/h, horizontal 45–75 kW above 1 ton/h) → discharge silo → extruder feed
- Premium configuration: Add a pipeline hot air dryer between the centrifugal stage and discharge silo for 80–120°C drying to 0.5–1% final moisture (suitable for fiber-grade extrusion or premium pellet markets)
- Material of construction: Carbon steel acceptable for HDPE/PP (no food-contact requirement), saving 25–40% on capital vs. stainless
Total drying section investment: $15,000–$50,000 for standard configuration; $50,000–$120,000 for premium with thermal stage. Most rigid plastic recycling lines (HDPE crates, PP drums, mixed rigid) use the standard configuration. See our integrated 강성 플라스틱 세척 라인 for the full upstream layout.
Configuration C: PE/PP Film Drying Line (500–2,500 kg/h)
Film cannot be processed by standard centrifugal dewatering — the long flexible material wraps around rotor paddles and stalls the machine. Film drying lines use either screw-press squeezers or anti-wrap centrifuges, plus mandatory thermal drying because film holds water surface area more aggressively than rigid flakes.
- Stage 1 — Mechanical dewatering: 플라스틱 필름 압착기 (screw press, 30–110 kW) for 500–1,500 kg/h, OR high-speed film centrifugal dewatering machine (anti-wrap rotor, 45–90 kW) for 1,500+ kg/h. Outlet moisture: 8–15%, plus densification if using squeezer.
- Stage 2 — Thermal drying: Hot air dryer at 80–120°C (lower than rigid flakes — film softens earlier). Outlet moisture: 1–3%.
- Stage 3 — Optional agglomeration: If using squeezer (which densifies), the output is ready for extrusion. If using centrifugal, a separate plastic film agglomerator may be needed to compact the dried film for stable extruder feeding.
Total drying section investment: $40,000–$120,000 for standard PE/PP film line. Add 15–25% for high-volume operations using anti-wrap centrifugal in addition to (or instead of) squeezer. Integration with the upstream washing line is critical — see our PE film washing line efficiency guide for inlet moisture control.
Configuration D: Mixed Rigid Plastic Drying Line (300–1,500 kg/h)
For post-consumer mixed rigid waste (HDPE bottle caps, PP containers, PET fragments, ABS housings combined), the limiting material in the stream determines the drying line configuration. If the output goes to low-grade extrusion (recycled lumber, garden furniture, low-spec pallets), centrifugal dewatering alone is sufficient. For higher-spec applications, add a thermal stage sized for the most demanding material (typically PET).
- Low-grade output: Centrifugal dewatering machine (37–55 kW) → discharge silo. Final moisture: 3–5%. Suitable for low-spec extrusion.
- Medium-grade output: Add hot air pipeline dryer at 100–130°C. Final moisture: 0.5–1.5%. Suitable for general-purpose extrusion.
- Material of construction: Stainless steel recommended (mixed waste includes PET fragments which need food-contact-grade equipment if any food-contact end-use is anticipated)
Total drying section investment: $20,000–$60,000 for standard mixed line; $50,000–$120,000 with thermal stage.
Equipment Sizing & Capacity Matching Rules
The most common drying line failure is mismatched capacity between stages — typically an undersized centrifugal dewatering machine or an oversized thermal dryer running at part-load (which wastes 20–30% of its rated energy). These three rules prevent the most expensive sizing errors:
Rule 1: Size for Peak Throughput, Not Daily Average
Recycling lines run in batches. A “10 ton/day” line typically processes 8 hours of actual operation with 1.5–2× peak feed rate during stable operation. Daily tonnage divided by 24 hours understates peak throughput by 2–3×. Calculate peak as: (daily tonnage × 1.6) ÷ actual operating hours. Size the centrifugal stage for peak; thermal stage can be sized at peak × 0.85 because the buffer absorbs short-term spikes.
Rule 2: Match Centrifugal Stage to Washing Line Discharge
The centrifugal dewatering machine must accept the washing line’s full discharge rate without back-pressure. Friction washers and float-sink tanks discharge intermittently — peak discharge can be 2× the average. Size the centrifugal at 120% of peak washing discharge, with a 5-minute buffer hopper between them to smooth flow. Undersizing causes the washing line to back up and overflow; oversizing wastes capital.
Rule 3: Size Thermal Stage by Water Mass, Not Material Mass
Thermal dryer capacity is determined by water evaporation rate, not flake throughput. A 1 ton/h flake stream entering at 4% moisture contains 40 kg/h water; entering at 8% moisture contains 80 kg/h water. The thermal dryer must handle the worst-case water load — which is determined by your centrifugal outlet moisture. Specify centrifugal outlet at 3–4% maximum to keep thermal stage size reasonable. See our centrifugal vs. air drying energy comparison for the kWh/ton calculations.
Buffer & Flow Control Strategy
Buffer hoppers between drying line stages are not optional storage — they’re flow control devices that prevent equipment from cycling on/off (which wastes 20–30% of rated energy and shortens motor life). Three buffer points matter:
| Buffer Position | 용량 | 기능 |
|---|---|---|
| Pre-centrifugal (between washer and dewatering) | 5 min throughput | Smooths intermittent washer discharge into continuous dewatering feed |
| Post-centrifugal (between dewatering and thermal) | 15–30 min throughput | Allows thermal dryer to run continuously despite centrifugal cycle gaps; absorbs CIP/cleaning interruptions |
| Pre-extruder (between drying and pelletizer) | 30–60 min throughput | Decouples extrusion from drying; allows extruder maintenance without stopping drying line |
For PET lines, the post-centrifugal buffer should be enclosed and dehumidified — amorphous PET reabsorbs ambient moisture quickly, undoing the dewatering work in 30–60 minutes of exposure to humid air. The buffer hopper between the thermal dryer and crystallizer should be heated to 100–120°C to prevent condensation and maintain temperature ramp.
Automation & Control System Architecture
A modern plastic recycling drying line uses a centralized PLC (Siemens S7-1500, Mitsubishi Q-series, or Allen-Bradley ControlLogix) coordinating individual stage controls. Required functions:
- Throughput pacing — washing line discharge rate sets the master pace; downstream stages auto-adjust feed rates to match
- Temperature PID control — pipeline dryer air temperature with ±2°C tolerance, crystallizer with ±5°C, all feedback-controlled
- Moisture monitoring — inline NIR or capacitive moisture meters at centrifugal outlet, post-thermal, and extruder feed
- Energy management — kWh/ton tracking per stage with operator dashboard; alarms when consumption exceeds 110% of baseline
- 안전 인터록 — emergency stops, motor overload protection, temperature alarms, level switches on all hoppers
- Remote monitoring (optional) — VPN-accessible HMI for off-site troubleshooting and OEM support
Avoid distributed control where each stage runs independently — coordinated PLC control reduces operator workload by 60% and prevents cascade failures (e.g., thermal dryer overheating because centrifugal upstream stopped feeding).
Integration with Washing Line (Upstream)
The drying line’s design starts at the washing line discharge, not at the centrifugal inlet. Three integration points determine drying line performance:
Discharge Moisture from Washing
Friction washers discharge at 30–40% surface moisture. Float-sink tanks discharge at 35–45%. Hot wash systems discharge at 30–35% but at 60–70°C — the higher temperature reduces thermal stage energy demand by 5–10%. Specify washing line discharge moisture in writing before sizing the drying line.
Particle Size Distribution
Granulator output upstream of washing affects centrifugal dewatering performance significantly. Flakes 8–12 mm are optimal for centrifugal dewatering — smaller fines (under 4 mm) escape through the screen as material loss; larger pieces (over 20 mm) reduce dewatering efficiency. Confirm your 과립기 스크린 크기 matches the centrifugal screen specification.
Continuous vs. Batch Discharge
Modern washing lines discharge continuously; older or batch-style lines discharge in pulses. Batch discharge requires a larger pre-centrifugal buffer (10 min vs 5 min) and tolerates lower-rated centrifugal capacity. If retrofitting drying onto an existing batch washing line, oversize the buffer rather than the centrifugal.
Integration with Extruder (Downstream)
The drying line’s outlet moisture must match the extruder’s feed throat specification — measured at the extruder feed, not at the dryer outlet. Hygroscopic materials (especially PET) reabsorb moisture during transfer, so installation matters as much as drying capacity.
- Transfer distance — keep dryer-to-extruder distance under 10 m for PET; longer runs require dehumidified transfer pipes
- Storage atmosphere — final hopper before extruder should be sealed and (for PET) dehumidified to dew-point ≤-30°C
- Inline moisture monitoring — install moisture meter at the extruder feed throat; sub-1% PET applications need real-time feedback to the drying line PLC
- Vent management — single-screw extruders need a moisture vent at zone 2; twin-screw extruders tolerate higher inlet moisture but require degassing zones
Layout & Footprint Planning
Drying line footprint depends heavily on the configuration but typically follows these scaling rules:
| 구성 | Footprint (Length × Width) | Headroom | Total Area |
|---|---|---|---|
| HDPE/PP standard (centrifugal only) | 4 × 2 m | 3 m | ~8 m² |
| HDPE/PP premium (with thermal) | 12 × 2 m | 3.5 m | ~24 m² |
| PE/PP film with squeezer + thermal | 10 × 3 m | 3 m | ~30 m² |
| PET sheet/fiber line | 15 × 3 m | 4 m | 약 45 m² |
| PET 병에서 병으로 재활용 (4단계 완전 공정) | 20 × 4 m | 5 m (결정화기 높이) | 약 80 m² |
Add 50% to these figures for maintenance access, electrical panels, and operator walkways. Pipeline hot air dryers benefit from vertical stacking (the 15–30 m heated duct can spiral upward), reducing horizontal footprint at the cost of headroom and crane access.
건조 라인 설계 시 흔히 저지르는 5가지 실수
실수 1: 자본을 절약하기 위해 원심 분리 단계를 생략하는 것
열만을 이용해 모든 물을 증발시키려면 4~6배 더 많은 에너지가 소요됩니다. 시간당 1톤 처리 용량의 순수 열 방식 라인은 톤당 250kWh 이상을 소모하는 반면, 원심 분리식 전처리 단계를 거치는 경우 톤당 150~230kWh만 소모합니다. 5년 동안 $0.10/kWh의 단가와 연간 4,000시간 가동 시, 에너지 비용 차이는 $80,000을 초과하며, 이는 설비 투자 비용에서 절약되는 $15,000보다 훨씬 더 큰 금액입니다. 예산이 빠듯하더라도 항상 기계적 탈수 공정을 포함시켜야 합니다.
실수 2: 단계 간 버퍼 용량이 부족함
Buffer hoppers under 10-min capacity force the thermal dryer to cycle on/off as the centrifugal stage produces uneven flow. Cycling wastes 20–30% of rated energy and shortens heater bank life by 40%. Install minimum 15-min buffer between centrifugal and thermal stages, 30-min between drying and pelletizer.
실수 3: 압출기에서 수분 모니터링을 하지 않음
건조 라인 출구 수분은 건조기에서 측정되지만, 폴리머의 품질은 압출기 공급 수분에 의해 결정됩니다. 흡습성 소재는 이송 과정에서 수분을 재흡수합니다. 압출기 공급구에 인라인 수분 측정기를 설치하십시오. 이를 설치하지 않으면 펠릿이 품질 검사에서 불합격 판정을 받을 때까지 재흡수 문제를 파악할 수 없습니다.
실수 4: 건축 자재의 부적합
Carbon steel centrifugal rotor on a PET line corrodes within 18 months — replacement cost ($8,000–$12,000) eclipses the original 25–40% capital savings. Specify 304 stainless steel for any line handling PET, food-contact applications, or PVC (chlorine corrosion). Carbon steel acceptable for HDPE/PP-only operations.
실수 5: 유지보수 접근 계획 미수립
원심 탈수기는 스크린 교체(수직형) 또는 끝단 커버 제거(수평형)를 위해 상단 접근이 가능해야 합니다. 파이프라인식 열풍 건조기는 6~12개월마다 히터 뱅크에 접근할 수 있어야 합니다. 각 기계의 최소 두 면에 1.0 m의 여유 공간을 확보하고, 수직 접근을 위해 2.5 m의 천장 높이를 확보하십시오. 설치 공간이 협소한 경우, 라인 수명 기간 동안 유지보수 시간이 3~5배 더 소요됩니다.
자주 묻는 질문
플라스틱 건조 라인과 플라스틱 세척 및 건조 라인의 차이점은 무엇인가요?
플라스틱 세척 및 건조 라인은 오염된 폐기물의 투입부터 압출에 바로 사용할 수 있는 건조된 플레이크가 생산될 때까지의 일련의 과정을 아우르는 통합 시스템으로, 일반적으로 길이가 50~80m입니다. 플라스틱 건조 라인은 단순히 건조 구간(원심 분리 + 열 건조 단계, 경우에 따라 결정화기 + 흡습제)만을 말하며, 길이는 일반적으로 8~25m입니다. 건조 라인은 세척 및 건조 라인의 하위 시스템입니다. 완비된 설비를 구매할 때는 대개 통합 세척 및 건조 라인을 구매하며, 기존 세척 공정에 건조 능력을 추가할 때는 건조 라인만 구매합니다.
플라스틱 재활용 건조 라인의 비용은 얼마인가요?
For a 1,000 kg/h line: HDPE/PP standard (centrifugal only) $15,000–$50,000. PE/PP film standard (squeezer + thermal) $40,000–$120,000. PET sheet/fiber line $80,000–$180,000. PET bottle-to-bottle full line (centrifugal + thermal + crystallizer + desiccant pellet dryer) $200,000–$400,000. Mixed rigid line $20,000–$60,000 standard, $50,000–$120,000 with thermal stage. The drying section typically represents 20–35% of total recycling line capital cost.
현재의 씻기 라인에 건조 라인을 추가할 수 있나요?
네 — 건조 용량 증설은 흔히 이루어지는 업그레이드입니다. 확인해야 할 세 가지 요소는 다음과 같습니다: 기존 세탁기의 배출 수분량(측정해야 하며, 원래 사양서를 그대로 믿어서는 안 됨), 최대 배출량(원심분리기 용량을 결정함), 그리고 신규 장비를 설치할 물리적 공간입니다. 대부분의 개조 작업에는 전기 배전반 업그레이드(건조 라인이 60~120 kW의 부하를 추가함)와 세척기 배출구와 새로운 원심분리기 사이에 버퍼 호퍼가 필요합니다. 통합 엔지니어링 비용으로 인해 총 개조 비용은 일반적으로 신규 건조 라인 설치 비용의 1.5배 정도 소요됩니다.
How do I size a buffer hopper for my drying line?
Buffer capacity in kg = throughput in kg/min × buffer time in minutes. For 1 ton/h (16.7 kg/min) with 15-minute buffer between centrifugal and thermal stages: 16.7 × 15 = 250 kg buffer capacity. With bulk density of washed PET flakes at ~250 kg/m³, that’s 1.0 m³ hopper volume. Add 30% headroom for level swings, so spec a 1.3 m³ hopper. For pre-extruder buffers (30–60 min), the same calculation gives 500–1,000 kg / 2.0–4.0 m³.
PET 건조와 HDPE/PP 건조는 어떤 차이가 있나요?
PET는 흡습성이 있으며(주변 공기에서 0.4–0.5%의 수분을 흡수함), 수분 함량이 50 ppm을 초과하는 상태에서 압출 온도에 노출되면 가수분해에 의한 사슬 절단이 발생합니다. HDPE/PP는 0.01% 미만의 수분을 흡수하며 가수분해되지 않습니다. 실질적인 영향: PET는 병에서 병으로의 생산 과정에서 4단계의 건조 공정(원심 분리 + 열 건조 + 결정화 + 흡착제 건조)이 필요한 반면, HDPE/PP는 대개 원심 분리 탈수 및 선택적인 열 건조만으로도 충분합니다. 동등한 최종 제품 수분 사양을 기준으로 할 때, PET 건조 라인의 자본 비용은 일반적으로 HDPE/PP보다 톤/시간당 4~6배 더 높습니다.
플라스틱 재활용 건조 라인을 설치하는 데 얼마나 오래 걸립니까?
계약 체결부터 시운전까지: 표준 사양의 경우 90~150일, 완전한 PET 병-투-병 라인의 경우 150~240일이 소요됩니다. 장비 제조에는 일반적으로 30~90일이 소요되며, 아시아에서 해상 운송에 25~45일이 추가되고, 현장 기계 설치에는 5~15일이 걸리며, 전기 및 PLC 시운전에 5~10일이 소요되고, 운영자 교육 및 성능 테스트에 7~14일이 더 소요됩니다. 통관 지연, 도면 수정, 설치 중 기계적 적합성 문제 등에 대비하여 30일의 여유 일정을 확보하십시오.
결론
적합한 플라스틱 재활용 건조 라인은 투입 원료, 최대 처리량, 최종 제품의 수분 함량 규격 순으로 결정됩니다. 먼저 원료(PET, HDPE/PP, 필름 또는 혼합)부터 고려하십시오. 이것이 구성 템플릿을 결정합니다. 그런 다음 일일 평균 처리량이 아닌 최대 처리량에 맞춰 규모를 설정하십시오. 각 단계의 용량을 인접 단계와 조화롭게 맞추고, 적절한 버퍼 호퍼를 설치하며, 분산형 단계 제어 방식보다는 중앙 집중식 PLC 제어를 사용하십시오. 무엇보다도, 자본 비용을 절감하기 위해 기계적 탈수 단계를 절대 생략해서는 안 됩니다. 에너지 비용 차이로 인해 12~24개월 이내에 절감액보다 더 많은 비용이 발생하게 될 것입니다.
Energycle는 300 kg/h에서 3,000 kg/h 용량의 완전한 플라스틱 재활용 건조 라인을 설계 및 공급하며, 여기에는 5가지 기능 구역 전체와 상류 세척 공정 및 하류 펠릿화 공정과의 연동이 포함됩니다. 당사의 표준 패키지에는 라인 배치 도면, 고객사의 특정 폐기물 유동을 활용한 재료 시험, 브랜드 부품(지멘스 PLC, SEW 기어박스, SKF 베어링), PET 용도를 위한 304 스테인리스 구조, 그리고 현장 시운전이 포함됩니다. 재료 유형, 처리량 요구 사항, 원하는 출력 크기를 가진 귀사의 원료 종류, 처리량 목표 및 최종 제품의 수분 함량 사양을 바탕으로, 당사는 장비 목록, 배치도 및 설치 일정이 포함된 종합적인 건조 라인 제안서를 제공해 드리겠습니다.
