Cream Separator Working Principle and Maintenance
Working Principle
Cream separators use centrifugal force to separate cream from milk. Milk has a density of 1.03 g/ml while fat has a density of 0.92 g/ml. When milk enters the separator bowl rotating at high speed, the denser skim milk moves outward while the lighter cream (fat globules) moves toward the rotation axis. Cream is continuously discharged through the axial outlet while skim milk flows to the outer disc stack space.
Key Parameters
- Milk density: 1.03 g/ml
- Fat density: 0.92 g/ml
- Residual fat in skim milk: 0.04-0.07%
- Sediment amount: approximately 1 kg per 10,000 liters
- Sediment space volume: 10-20 liters
- Discharge interval: 30-60 minutes
- Optimal bacteria removal temperature: 55-60 deg C
- Preheating temperature for separation: 35-40 deg C (up to 50 deg C, but not higher to avoid protein coagulation)
Operating Procedures
Starting the Separator
- Check that all components are intact, undamaged, and not loose
- Thoroughly clean the interior and exterior of the separator
- Ensure material to be separated meets processing requirements
- Start the separator and gradually increase to required speed
Production Mode
- Supply product to the separator
- Discharges are automatically performed at set time intervals (typically 30-60 minutes)
- Monitor pressure stability and discharge status
Cleaning Procedures (CIP)
- Water rinse mode: Large discharge frequently
- Lye/acid cleaning mode: Small discharge every 6 minutes
- Final water rinse: Large discharge every 3 minutes
- Note: Lye/acid cleaning must always be followed by water rinse
Stopping the Separator
- Interrupt product feed
- Perform cleaning sequence
- Activate brake to stop rotation
- Machine free-stopping time is over 30 minutes; brake reduces this to approximately 10 minutes
Maintenance Methods
- Safety: High-speed centrifuges contain high kinetic energy. Only qualified personnel may operate and maintain
- Inlet Inspection: Check cooling water inlet holes (1.2mm), O-rings, seal rings, and wear rings
- Height Adjustment: Correct height setting provides proper clamping force between seal ring and wear ring. Measurement should be 36.5-37.5mm
- Axial Seal: Defective axial seals cause leakage during production. If seal surface is not excessively damaged, it can be polished and reused
- Gearbox Oil: Check oil quality and level regularly. Clean bottom of gearbox when changing oil
- Regular Lubrication: Lubricate bearings and gears regularly to reduce wear and noise
- Corrosion Prevention: Regularly inspect metal parts contacting product. If corrosion is found, treat promptly
- Electrical Inspection: Regularly check electrical components for safety and stability
Calculating Cream Fat Content
If whole milk contains 4% fat at 20,000 L/h flow, total fat separated is (4 x 20000) / 100 = 800 L/h. If target cream fat content is 40%, cream discharge volume is (800 x 100) / 40 = 2000 L/h, with 800 L/h pure fat and 1200 L/h skim milk. Throttle valves at cream and skim milk outlets adjust volumes for target fat content.
