**Application details of Roots vacuum pump for negative pressure powder conveying**
**(Principles, System Composition, Selection Guidelines, and Industry Cases)**
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**1、 Working principle**
The negative pressure powder conveying system uses a Roots vacuum pump (or a combination of Roots and screw pumps) to generate a negative pressure airflow (usually -20~-80 kPa) in the pipeline. The powder is sucked into the pipeline through a suction nozzle, and after passing through a separator (cyclone separation or filter cartridge filtration), the powder falls into a storage tank, and the clean gas is discharged into the atmosphere or recovered.
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**2、 Core components of the system**
|* * Component * * | * * Function * * | * * Key Parameters * *|
|-------------------|-------------------------------------------------------------------------|--------------------------------|
|Roots vacuum pump provides negative pressure power to maintain stable airflow. Vacuum degree:- 30~-80 kPa<br>Flow rate: 1~100 m3/min|
|* * Suction nozzle * * | Powder inlet, designed with a Venturi structure (anti clogging) | Material: 304/316L stainless steel|
|* * Conveyor pipeline * * | Wear resistant pipeline (such as ceramic lining) | Wind speed: 15-25 m/s (anti sedimentation)|
|* * Separators * * | Gas solid separation (cyclone separation+filter cartridge secondary filtration) | Filtration accuracy: 0.5~5 μ m|
|* * Control system * * | PLC automatic control suction separation discharge process | Explosion proof option: Ex d Ⅱ BT4|
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**3、 Application advantages**
1. * * Pollution free * *: Fully enclosed transportation to prevent dust leakage (in compliance with OSHA standards).
2. * * Flexible Layout * *: Pipelines can be arranged in multiple directions (horizontal/vertical/curved) to adapt to complex factory buildings.
3. * * Low loss * *: Transport damage rate<0.1 (compared to mechanical transport).
4. * * Easy to maintain * *: No mechanical moving parts in contact with materials, minimal wear and tear.
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**4、 Typical Industry Applications**
|* * Industry * * | * * Material Conveying * * | * * Vacuum Degree Requirements * * | * * System Configuration Case * *|
|----------------|-----------------------|---------------------|-------------------------------------|
|* * Food * * | Flour, milk powder | -30~-50 kPa | 316L stainless steel pump+food grade filter cartridge|
|Chemical industry * * | Titanium dioxide, carbon black | -50~-70 kPa | Explosion proof Roots pump+ceramic lined pipeline|
|* * Pharmaceutical * * | Raw materials and excipients | -40~-60 kPa | GMP certification system (oil-free design)|
|Lithium ion battery * * | Graphite negative electrode material | -60~-80 kPa | Inert gas protection (oxidation prevention)|
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**5、 Key parameters for selection**
1. * * Conveying Capacity * *:
-Calculation formula:` Q (kg/h)=Airflow velocity (m/s) × Pipeline cross-sectional area (m2) × Material density (kg/m3) × 3600 × Mixing ratio`
-Mixing ratio (gas-solid ratio): usually 0.5-5 (powder: gas).
2. * * Vacuum pump selection * *:
-Single stage Roots pump: suitable for short distance (<50m) transportation at -30~-50 kPa.
-Roots+screw pump: suitable for -60~-80 kPa, long-distance (>100m) or high-density powders.
3. * * Pipeline Design * *:
-Pipe diameter: Calculated based on wind speed of 15-25 m/s (e.g. DN80 pipeline required for conveying 5 t/h flour).
-Bend radius ≥ 10 times the pipe diameter (to reduce wear).
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**6、 Common Problems and Solutions**
|* * Problem * * | * * Reason * * | * * Solution * *|
|-------------------|------------------------|--------------------------------|
|Low conveying efficiency | Pipeline leakage/insufficient vacuum | Leak detection (soap water method)+increase pump power|
|* * Powder deposition * * | Low wind speed/high humidity | Increase airflow velocity to>18 m/s+|
|* * Filter cartridge blockage * * | Backblowing system failure | Replace pulse valve+adjust blowback cycle|
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**7、 Maintenance points**
1. * * Daily inspection * *: Vacuum gauge reading, filter cartridge pressure difference (>5 kPa needs to be cleaned).
2. * * Monthly maintenance * *: Clean the separator and check for pipeline wear (especially at bends).
3. * * Annual overhaul * *: Replace bearings (with a lifespan of approximately 20000 hours) and verify valves.
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**Summary: The Roots vacuum pump system for negative pressure powder conveying has the core advantages of * *, cleanliness, and flexibility * *. The selection should comprehensively consider * * material characteristics, conveying distance, and vacuum requirements * *. It is recommended to prioritize the use of anti jamming rotor design (such as three leaf type) and wear-resistant materials (such as ceramic coated pipelines) to reduce long-term operation and maintenance costs.
