Conductive Hollow Paddle Vacuum Dryer for Municipal Sludge Chemical Paste & Food Powder
Working Principle
Heat medium (saturated steam, thermal oil, or hot water) continuously enters the hollow main shaft and wedge paddles through rotary joints, while the shell jacket is simultaneously heated, creating a dual-channel heating surface. The hollow paddle shaft rotates at low speed, and material fed from the inlet is continuously stirred and conveyed toward the outlet. The special wedge structure compresses and expands material alternately, producing strong shear and dispersion that constantly renews the material on heat transfer surfaces for enhanced heat transfer and self-cleaning, preventing sticking and scaling. An adjustable baffle at the outlet maintains full coverage of heat transfer surfaces by material; material moves in plug flow with uniform residence time, ensuring consistent final moisture content. Vapor is discharged through the top vent, dedusted, and condensed. The entire process is fully enclosed with no dust leakage.
Product Overview
The hollow paddle dryer (conducting type paddle dryer) is a horizontal, agitated continuous drying machine based on indirect heat conduction. The main body features a jacketed shell with a hollow shaft densely fitted with wedge-shaped hollow paddles. Heat medium is fed through rotary joints into both the shell jacket and hollow paddle shaft, transferring heat to material through metal walls for efficient continuous drying. Owing to its high thermal efficiency, strong self-cleaning capability, and wide material adaptability, it is widely applied in environmental protection, chemical, food, pharmaceutical, petrochemical, and metallurgical industries for paste, granular, powder, and slurry materials, performing drying, cooling, heating, sterilization, reaction, and low-temperature calcination.
Typical Material Drying Data
| Material Type | Initial Moisture | Final Moisture | Heat Medium Temp. | Industry |
|---|
| Municipal Dewatered Sludge | 70%~80% | 10%~25% | 150~200°C (Steam) | Wastewater / Environmental |
| Industrial Chemical Sludge | 60%~70% | 15%~30% | 160~220°C (Thermal Oil) | Chemical / Environmental |
| Printing & Dyeing Sludge | 75%~85% | 20%~30% | 150~200°C (Steam) | Textile / Environmental |
| Starch | 30%~40% | 8%~12% | 120~150°C (Steam) | Food |
| Polymer Sludge (Latex Coagulum) | 40%~60% | 5%~15% | 120~160°C (Steam) | Plastic / Polymer |
| Coal Slime | 25%~35% | 8%~15% | 180~250°C (Thermal Oil) | Coal / Mining |
| Pharmaceutical / Fermentation Residue | 60%~75% | 10%~20% | 100~140°C (Steam / Vacuum) | Pharmaceutical / Biological |
The above data are measured on industrial sites; actual results vary with material properties and process conditions.
Key Features
- Fully enclosed, clean operation: Complete system is sealed with no dust leakage and small exhaust volume, meeting environmental and GMP requirements for pharmaceutical and food industries.
- Wide material applicability: Handles paste, granular, powder, and slurry materials; one machine performs drying, cooling, heating, sterilization, reaction, and low-temperature calcination.
- High thermal efficiency, energy saving: Indirect conduction heating with 80%~90% heat utilization, saving 30%~50% energy compared with hot air dryers; only 1.2~1.5 kg steam per kg water evaporated.
- Wedge self-cleaning design: Alternating compression and expansion of wedge paddles self-clean heat transfer surfaces, effectively handling sticky, wall-adhering, and high-viscosity materials (up to 500,000 cP).
- Gentle low-speed agitation: Shaft speed of only 3~30 RPM protects crystal structure and particle shape, suitable for heat-sensitive and fragile materials.
- High operational flexibility: Residence time adjustable through feed rate, shaft speed, and baffle height; stable, reliable operation with low maintenance cost.
Technical Parameters
| No. | Heat Transfer Area (m²) | Effective Volume (m³) | Evaporation Intensity (kgH₂O/h) | Motor Power (kW) | Shaft Speed (rpm) | Dimensions L*W*H (mm) |
|---|
| 1 | 3 | 0.06 | 10~60 | 2.2~3 | 10~30 | 3000*600*980 |
| 2 | 9 | 0.32 | 30~180 | 5.5 | 8~25 | 4200*1000*1500 |
| 3 | 13 | 0.59 | 50~260 | 7.5 | 8~20 | 5000*1200*1800 |
| 4 | 18 | 1.09 | 70~360 | 11 | 5~15 | 5800*1400*2100 |
| 5 | 29 | 1.85 | 120~580 | 15~18.5 | 5~15 | 6800*1600*2400 |
| 6 | 41 | 2.80 | 160~820 | 22 | 4~12 | 7800*1800*2600 |
| 7 | 52 | 3.80 | 200~1040 | 30 | 4~12 | 8800*2000*2800 |
| 8 | 68 | 5.20 | 270~1360 | 37~45 | 3~10 | 10000*2200*3000 |
| 9 | 81 | 6.50 | 320~1620 | 55 | 3~10 | 11000*2400*3200 |
| 10 | 110 | 9.00 | 440~2200 | 75~90 | 3~8 | 13000*2700*3500 |
Note: The above parameters are industry reference values; evaporation intensity is based on water. Actual capacity depends on initial and target moisture content, material properties, and heat medium temperature. Please provide material parameters for a tailored selection proposal.
FAQ & Services
- Heat media and temperature: Saturated steam (150~200°C), thermal oil (up to 320°C), or hot water (80~100°C); design temperature range -40°C to 320°C; cooling water can also be used for cooling operations.
- Material options: Carbon steel or 304 stainless steel as standard; 316L, 2205 duplex steel, Hastelloy, and titanium available; rubber or plastic lining and Teflon coating for anti-corrosion.
- Vacuum and closed-loop options: Vacuum type operates at 40~80°C for heat-sensitive or solvent-containing materials with solvent recovery; nitrogen circulation suits oxidation-prone and VOC-containing materials with zero emission.
- Vs. drum and flash dryers: The paddle dryer uses indirect conduction with 80%~90% thermal efficiency, ideal for paste, high-moisture, and high-viscosity materials. For sludge and filter cake, the paddle dryer is the preferred choice.
- Delivery and after-sales: Standard models delivered within 45~60 working days, customized models within 60~90 working days; 12-month warranty, free installation guidance and commissioning, free operator training, and lifetime technical support and spare parts supply.
We provide full-process service from material testing, solution design, manufacturing, installation, and commissioning to operator training. Customers can send material samples for lab pilot tests to obtain real drying data and a targeted selection proposal. Key components use internationally renowned brands (SKF/NSK bearings, Siemens/ABB motors, Schneider electric components) for long-term stable operation.
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