Rake Dryer
Drying Equipment
1. Product Overview
The rake dryer is a horizontal batch vacuum dryer that transfers heat mainly by conduction. It consists of a horizontal shell, a rotating rake shaft, a drive system, a vacuum system and a heating system. It is widely used for drying pastes, filter cakes and powdery or granular materials. Key features: an exceptionally wide range of suitable feed materials; high vacuum, which allows organic solvents to be recovered; continuous turning of the material by the rake teeth for uniform drying; and complete discharge.
2. Working Principle
Wet material is charged into the horizontal shell, which is then evacuated. A heating medium (steam, hot water or thermal oil) circulates through the jacket and heats the shell wall. The main shaft rotates the rake teeth slowly, so the material is continuously agitated, turned over and conveyed forward, constantly renewing its surface. The evaporated moisture or solvent is drawn off under vacuum and recovered in a condenser.
3. System Classification
By rake shaft configuration:
Standard rake dryer: fixed rake teeth with moderate agitation intensity / powders and general filter cakes
Rake dryer with chopper shaft: a high-speed chopper shaft mounted alongside the main shaft breaks up agglomerates / materials that cake readily and high-viscosity pastes
Continuous rake dryer: rotary air-lock valves at both ends enable continuous feeding and discharge / large-scale production of a single product
4. Detailed Technical Parameters
4.1 Common Materials
| Material | Typical Parts / Media | Remarks |
|---|---|---|
| 304 Stainless Steel | Shell, rake shaft, rake teeth | General chemical and food-grade service |
| 316L Stainless Steel | Strongly corrosive solvents, pharmaceutical materials | GMP compliant; outstanding corrosion resistance |
| Carbon Steel Q235B | Outer shell and supports | Economical; internal surfaces require anti-corrosion treatment |
4.2 Typical Specifications
| Effective Volume (L) | Heating Area (m²) | Rake Shaft Speed | Motor Power | Jacket Pressure |
|---|---|---|---|---|
| 100～500 | 3～12 | 5～15 | 2.2～5.5 | 0.2～0.4MPa |
| 500～2000 | 12～35 | 5～12 | 5.5～15 | 0.2～0.4MPa |
| 2000～8000 | 35～100 | 3～8 | 15～45 | 0.2～0.4MPa |
4.3 Design Conditions & Performance
| Parameter | Specification |
|---|---|
| Shell Vacuum | -0.096～-0.099MPa |
| Heating Temperature | ≤150℃ (steam/hot water); ≤250℃ (thermal oil) |
| Filling Coefficient | 30%～60% (depending on material form) |
| Drying Time | 4～16 hours per batch |
5. Electrical Parameters
| Region | Voltage | Frequency |
|---|---|---|
| China/Russia/Central Asia | 380V | 50Hz |
| Middle East/Southeast Asia/Africa | 400V / 415V | 50Hz |
| South Korea | 380V | 60Hz |
| Americas (if required) | 440V / 480V | 60Hz |
| Note: Please specify voltage and frequency for the main shaft motor, chopper motor and vacuum pump. |
6. Core Component Selection
| Component | Brand/Material | Features & Applications |
|---|---|---|
| Shell & Jacket | Custom-built | 304/316L with polished internal surface and a well-designed jacket flow path |
| Rake Shaft & Teeth | Custom-built | Cast or welded teeth arranged alternately left/right for two-way mixing |
| Mechanical Seal | Matched set | Packing or double mechanical seal, suitable for high vacuum |
| Vacuum System | Leybold / Chinese brands | Water-ring pump + condenser / Roots pump for efficient solvent recovery |
7. Typical Application Fields
Chemical industry: drying of dye, pigment and resin filter cakes
Pharmaceutical industry: drying of APIs, intermediates and extracts
Agrochemical industry: drying of pesticide technicals and intermediates
Environmental protection: drying of electroplating sludge and waste residues
8. Design Standards & Certifications
| Standard | Description |
|---|---|
| GB 150-2011 | Pressure vessels (applies to the jacket and vacuum shell) |
| ISO 9001:2015 | Quality management system |
| GMP | Good Manufacturing Practice |
| CE / EAC / GOST-R | Available on request for international orders |
9. Custom Optional Configurations
| Option | Details |
|---|---|
| Agitation Type | Standard rake teeth / high-speed chopper shaft |
| Heating Method | Steam / hot water / thermal oil |
| Discharge Method | Manual full-opening door / pneumatic flap valve / air-lock continuous discharge |
| Special Design | CIP (clean-in-place) / explosion-proof / integrated belt filter |
10. Warranty Terms
| Equipment Status | Warranty Period | Warranty Scope |
|---|---|---|
| Brand New | 12 months | Shell & jacket, rake shaft drive system, sealing system |
| Refurbished | 6 months | Shell & jacket, rake shaft drive system, sealing system |
| Idle | 3 months | Main functional components |
11. Packaging & Delivery
| Item | Packaging Method |
|---|---|
| Main Shell | Bundled bare with steel strapping or wrapped in tarpaulin |
| Rake Shaft / Motors / Pumps | Fully enclosed wooden cases |
| Electrical / Instruments | Waterproof-sealed packing, packed in wooden cases |
| Container or break-bulk shipping. On-site installation and commissioning guidance available. |
12. Information Required for Inquiry
12. Information Required for Quotation Material name and initial/final moisture content; material form (powder/filter cake/paste) and viscosity; batch size; drying temperature limits; solvent type and recovery requirements; preferred equipment condition (new/refurbished/idle); delivery terms (FOB/CIF/DDP); destination port.