It is used for products that need a large filtering surface and very frequent product changes, due to its simple operation and cleaning procedures. This is the least closed environment because the unit is opened for product removal, therefore additional measures may need to be taken for containment.
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Production Cycle and Design Advantages
Overview
The next few slides will walk through the entire Production Cycle, showing the feeding, cake washing, centrifugation, and discharge.
Feeding
The solid-liquid suspension is fed through the feed pipe into the centrifuge. It moves towards the filter cloth under the action of centrifugal force, and onto on a perforated drum. The solid part of the suspension is retained by the filter cloth, forming a cake, while the liquid filters through the cake. The liquid is discharged through the holes of the basket. The growth of the cake thickness is controlled by a mechanical paddle detector, which can automatically stop the feeding phase when the desired cake thickness is reached.
Cake Washing
Cake washing removes any impurities present in the cake. The washing liquid is distributed onto the product in the basket, and through nozzles located along the washing pipe. The liquid passes through the product, then passes from the filter bag and the holes of the basket, removing impurities present in the cake.
Centrifugation
Once the washing phase is complete, the centrifuge accelerates to the maximum speed allowable for the product being processed, and maintains that speed for a given amount of time to achieve the desired level of residual humidity in the product. At the end of the centrifugation, the centrifuge is stopped to discharge the product.
Discharge
The solids discharge can be achieved manually by means of: a shovel (Alfa/B), a lifting bag system (Alfa/SB), or automatically via a scraping knife/vacuum (Alfa/B-CA).
- Fine chemicals
- Pharmaceuticals
- API
- Batch filtering centrifuge with product discharge from the top
- Fixed frame or GMP design available
- Full inspection of process area and flat basket bottom is possible with GMP design
- Glove box operation (for high containment) is available
- Production of chemical and pharmaceutical products from synthesis processes
- Suitable for products requiring a large filtering surface area
- Simple operation and cleaning procedures allow for frequent change of production
- Sizes range from 350mm-1600 mm in basket diameter – See chart below
- ALFA/B: The simplest model with manual cake removal by hand shovel or, for small models, lifting a bag by hand. This model is used mainly for small sizes (filter bag and filter cloth may be used).
- ALFA/SB: The solids discharge is achieved by lifting the bag up (the most common system). An optional system can be used for “automatic” bag lifting.
- ALFA/SB CA: The solids are discharged by a knife and evacuated via a pneumatic system (vacuum). The system is only useable with easy products that can be pneumatically transported and dedicated productions. The advantage is to avoid contact between operator and the product and between the product and the external environment.
- Complete PLC controls with touch screen interface
- Switch between automatic, semiautomatic, and manual operation
- Variable frequency drive (VFD) speed control
- ATEX (Europe) electrical enclosures or NEC (North America)
- Optional instrumentation integrated into the control system including oxygen monitoring, temperature, pressure, liquid feed flow, N2 purge flow, effluent particle detection and fluid clarity
- The centrifuge should be cleaned at every change of product to avoid cross contamination between campaign productions. The fully automated centrifuge cleaning system is composed of 2 main stages: Washing Machine Effect and cleaning with spray balls, which can be alternated to achieve maximum cleaning and to optimize the consumption of the cleaning liquid.
- C.I.P. (Clean-In-Place) avoids cross contamination at every change of production
- Both options for the Washing Machine Effect cycle and spray balls are available
- Small footprint
- Filter options:
- Polypropylene or other fabrics of various micron sizes
- Sintered metal screen for microfiltration (down to 2 microns)
- Inertia base installation with visco dampers
- Optional cake detector for automatic loading without operator intervention and cake thickness monitoring
- System for dissolving the cake “in situ” to avoid typical solids discharge
- For smaller machines, a glove box can be provided for high containment
- Construction materials
- Parts in contact with the product: all stainless steels and special alloys are available, such as AISI 316L, AISI 904L, hastelloy, monel, alloy 59, 254 SMO, nickel, titanium, SAF 2205
- Surface coating option: Halar (ECTFE),
- Elastomers: antistatic and FDA certified, Teflon ETFE, and hard rubber
- Field service and technical support available
- Mechanical and electrical parts
- Process control and maintenance manuals
- Certifications and construction documentation
- Mechanical and electrical upgrades
Standard Sizes and Technical Data
|
Centrifuge model: ALFA (Unit) |
Basket Diameter (mm) |
Basket Length (mm) |
Filtering Surface (m2) |
Cake Volume (liters) |
Max Load (kg) |
Max Speed (RPM) |
G Factor (xg) |
Centrifuge Weight (kg) |
|---|---|---|---|---|---|---|---|---|
| 350/260 | 350 | 260 | 0.28 | 15 | 20 | 2800 | 1532 | 900 |
| 550/350 | 550 | 350 | 0.6 | 40 | 50 | 2550 | 2000 | 1200 |
| 630/400 | 630 | 400 | 0.8 | 63 | 80 | 1900 | 1250 | 1500 |
| 800/400 | 800 | 400 | 1.00 | 100 | 125 | 1500 | 1000 | 2900 |
| 1000/500 | 1000 | 500 | 1.57 | 200 | 250 | 1200 | 800 | 4000 |
| 1250/500 | 1250 | 500 | 1.96 | 315 | 400 | 1000 | 700 | 5300 |
| 1250/630 | 1250 | 630 | 2.47 | 400 | 500 | 1000 | 700 | 6000 |
| 1250/800 | 1250 | 800 | 3.14 | 500 | 625 | 1000 | 700 | 6500 |
| 1600/800 | 1600 | 800 | 4.02 | 800 | 1000 | 850 | 646 | 8000 |